JP2017215235A - Balance wheel and speed governor for timepiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a balance wheel capable of controlling change of inertia moment of the balance wheel accompanying temperature change and capable of suppressing deterioration in accuracy of rate due to the temperature change.SOLUTION: A balance wheel 2 includes: a balance staff 3; an arm part 4 extending from the balance staff 3 to the outside of the balance staff 3; and a rim part 5 extending in a circular arc shape along a circumferential direction around the balance staff 3 while being supported by the arm part 4. The arm part 4 is formed of a fiber-reinforced plastic having reinforcement fiber S, and an alignment direction of the reinforcement fiber S is arranged in a direction parallel to an extending direction A of the arm part 4.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a balance wheel used in a timepiece and a speed governor for the timepiece.

The mechanical timepiece needs to precisely adjust the accuracy of the vibration period of the speed governor (balance) in order to obtain an accurate rate (timepiece delay, degree of advance). This speed governor has a balance wheel and a hairspring, and a vibration cycle is represented by the following formula (1).
Where T: balance frequency of balance
I: Moment of inertia of balance wheel
K: Spring constant of the hairspring.
That is, the vibration period of the governor changes depending on the moment of inertia around the center of rotation of the balance wheel and the spring constant of the balance spring.

Here, a material that expands as the temperature rises is generally used for the balance wheel. For this reason, the diameter of the balance wheel increases when the temperature rises, and the moment of inertia increases. For the hairspring, a material whose Young's modulus decreases with increasing temperature is generally used. For this reason, when the temperature rises, the spring constant of the hairspring is lowered.
As a result, when the temperature rises, the moment of inertia of the balance wheel increases and the spring constant of the balance spring decreases, so the vibration period of the governor generally decreases at low temperatures and increases at high temperatures. It has become.

  On the other hand, in order to suppress deformation (expansion) due to the influence of heat, a speed control device in which a balance wheel is formed of a composite material containing reinforcing fibers (hereinafter referred to as “fiber reinforced plastic”) is known (for example, Patent Document 1).

JP-T-2007-533973

Here, it has been found that fiber-reinforced plastics generally have a lower coefficient of thermal expansion than synthetic resins that do not contain reinforcing fibers. Therefore, by forming the balance wheel with fiber reinforced plastic, it is possible to suppress the expansion of the balance wheel when the temperature rises.
However, even when the balance wheel is formed of fiber reinforced plastic, it is difficult to grasp the state of expansion of the balance wheel caused by the temperature rise only by using the fiber reinforced plastic. For this reason, the inertia moment of the balance wheel at the time of temperature rise cannot be appropriately controlled.

  The present invention has been made paying attention to the above-described problem, and appropriately controls a change in the moment of inertia of the balance wheel accompanying a temperature change, and can be used for a balance wheel and a watch capable of suppressing a decrease in accuracy of the rate due to the temperature change. An object is to provide a speed governing device.

  In order to achieve the above object, the present invention provides a balance, an arm portion extending from the balance stem to the outside of the balance, and a circumferential direction centered on the balance supported by the arm portion. An rim portion extending in an arc shape, and the arm portion is formed of fiber reinforced plastic having reinforcing fibers, and the orientation direction of the reinforcing fibers is set in a direction parallel to the extending direction of the arm portions. Has been.

  Therefore, in the balance wheel of the present invention, it is possible to appropriately control the change in the moment of inertia of the balance wheel due to the temperature change, and to suppress the decrease in the accuracy of the rate due to the temperature change.

It is a side view which shows the structure of the speed governor for timepieces of Example 1. FIG. FIG. 3 is a plan view showing a balance wheel of the time governor for a timepiece according to the first embodiment. FIG. 3 is a plan view of the balance wheel of the first embodiment in a normal temperature state. FIG. 3 is a plan view of the balance wheel of Example 1 in a high temperature state. FIG. 6 is a plan view showing a modification of the balance wheel of the time governor for timepiece according to the first embodiment. FIG. 6 is a plan view showing a further modification of the balance wheel of the time governor for the timepiece according to the first embodiment.

  EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the balance wheel and time regulator for timepieces of this invention is demonstrated based on Example 1 shown on drawing.

Example 1
[Configuration of speed control device for balance wheel and watch]
FIG. 1 is a perspective view showing a time governor for a timepiece according to the first embodiment. FIG. 2 is a plan view showing the balance wheel of the first embodiment. Hereinafter, based on FIG.1 and FIG.2, the structure of the balance wheel of 1st Example and the speed control apparatus for timepieces is demonstrated.

  A time governor (temple) 10 for a timepiece according to the first embodiment is built in a portable timepiece (for example, a wristwatch) and includes a hairspring 1 and a balance wheel 2 as shown in FIG.

  The hairspring 1 is, for example, a flat whisker that is spirally wound in one plane, the inner end is joined to the balance 3 of the balance wheel 2, and the outer end is a balance of a movement of a portable watch. It is fixed to a receiver (not shown).

  As shown in FIG. 2, the balance wheel 2 has a balance stem 3, an arm portion 4, a rim portion 5, and a weight portion 6.

  The balance stem 3 is a shaft member located at the center of the balance wheel 2, and the top and bottom of the shaft are rotatably supported by a base plate of a movement of a portable timepiece and a balance holder (both not shown).

  The arm portion 4 is formed with a through hole 4a into which the core 3 is fitted at the center C, and a pair of arms 4b, 4c extending from the through hole 4a in the radial direction (radial direction) centering on the core 3. have. The pair of arms 4b and 4c extend in opposite directions with the through hole 4a interposed therebetween, and the lengths from the through hole 4a to the respective tips 4d and 4e are formed to be equal. The center C of the arm portion 4 coincides with the rotation center of the balance 3.

The rim portion 5 extends in an arc shape along the circumferential direction with the balance 3 as the center, and has an annular shape without a cut in the circumferential direction. The rim portion 5 is supported by connecting the tip 4d of the arm 4b and the tip 4e of the arm 4c.
Here, in a state where the arm portion 4 and the rim portion 5 are coupled, the center C of the arm portion 4 coincides with the center of the rim portion 5, and the arm portion 4 extends from the center C in the diameter direction of the rim portion 5. ing. In other words, the extending direction (axial direction) A of the arm portion 4 coincides with the diameter direction of the rim portion 5.

The weight portion 6 has a columnar shape, and one end 6a in the extending direction (axial direction) B of the weight portion 6 is integrated with the rim portion 5, and the radial direction (radiation) about the balance 3 is centered. The rim portion 5 extends in the direction). Here, a pair of weight portions 6 are provided at positions to be the target with the balance 3 interposed therebetween, and both of the extending directions B are perpendicular to the extending direction A of the arm portion 4 (perpendicular direction). Is set to
Further, the weight portion 6 is not in contact with the rim portion 5 except for one end 6a. Therefore, when the weight portion 6 is thermally expanded or contracted in response to a change in temperature, the weight portion 6 is not restricted to the inner side in the radial direction of the rim portion 5 with respect to the one end 6a integrated with the rim portion 5. It expands and contracts.

And in this Example 1, the arm part 4, the rim | limb part 5, and the weight part 6 are integrally molded with the fiber reinforced plastics.
Here, “fiber reinforced plastic” refers to a prepreg sheet formed by impregnating a woven fabric produced with the direction of reinforcing fibers (in the state of long fibers) impregnated with a synthetic resin as a main raw material. It is a plastic composite material with increased strength of synthetic resin. Since the fiber has directionality, anisotropy appears in the coefficient of thermal expansion and strength depending on the orientation of the fiber. That is, this fiber-reinforced plastic has a low coefficient of thermal expansion in the direction along the fiber direction (parallel direction) and a high coefficient of thermal expansion in the direction orthogonal to the fiber direction (vertical direction). In Example 1, a unidirectional material (UD material) in which reinforcing fibers are oriented in one direction is used.
“Integral molding” means that the product is integrally molded simultaneously with the joining of the members without using secondary bonding or mechanical joining. The arm part 4, the rim part 5, the weight part 6, Is to form each part at the same time. Here, the balance wheel 2 is formed by punching a plate-like fiber reinforced plastic formed by laminating prepreg sheets with a mold.

  Note that carbon fibers, glass fibers, boron fibers, aramid fibers, polyethylene fibers, and the like can be used as the reinforcing fibers used in the fiber-reinforced plastic. Moreover, as a synthetic resin which is a main raw material of fiber reinforced plastic, a thermosetting resin such as unsaturated polyester, epoxy resin, or phenol resin may be used, or a thermoplastic resin such as polyamide resin or methyl methacrylate may be used. May be.

  And in this Example 1, as shown in FIG. 2, the orientation direction of the reinforced fiber S which the fiber reinforced plastic has is parallel to the extending direction A of the arm portion 4 (the axial direction of the arm portion 4). (The direction along the extending direction A) is set. Moreover, in Example 1, since the extending direction B of the weight part 6 is orthogonal to the extending direction A of the arm part 4, the orientation direction of the reinforcing fiber S is the extending direction B of the weight part 6 ( A direction perpendicular to the axial direction of the weight portion 6 is set.

[Operation of the speed control device for balance wheel and watch]
3 shows a plan view of the balance wheel of Example 1 in a normal temperature state, and FIG. 4 shows a plan view of the balance wheel of Example 1 in a high temperature state. Hereinafter, based on FIG.3 and FIG.4, the effect | action of the balance wheel of Example 1 and the governor for timepieces is demonstrated.

  As shown in FIG. 3, the balance wheel 2 of the first embodiment is in an almost perfect circle state in which the rim portion 5 has a diameter dimension R1 around the center C in a normal temperature state (before deformation according to a temperature change). In addition, the center of gravity 6b of the weight portion 6 is located at a distance L1 from the center C in the radial direction. Here, “room temperature” refers to a temperature range of about 20 degrees ± 5 degrees.

  The balance wheel 2 according to the first embodiment has a temperature characteristic (propensity to expand due to a temperature rise) having a positive thermal expansion coefficient. On the other hand, the fiber-reinforced plastic forming the balance wheel 2 has the lowest thermal expansion coefficient in the direction along the orientation direction of the reinforcing fibers S, and the thermal expansion coefficient increases as the deviation from the orientation direction of the reinforcing fibers S increases. The coefficient of thermal expansion in the direction perpendicular to the orientation direction of the reinforcing fibers S is the highest.

  That is, when the temperature of the balance wheel 2 rises from room temperature, the arm portion 4 hardly expands (extends) because the coefficient of thermal expansion along the extending direction A is low as shown in FIG.

On the other hand, the rim portion 5 expands (expands) toward the outside in the radial direction with the center C as the center, but the portion where the tips 4d and 4e of the arm portion 4 are joined and the vicinity thereof (the portion indicated by the broken line α) ), The deviation between the radial direction and the orientation direction of the reinforcing fibers S is small. Moreover, the arm part 4 hardly expands (extends). For this reason, the portion of the rim portion 5 to which the arm portion 4 is coupled and the vicinity thereof (the portion indicated by the broken line α) have a relatively low coefficient of thermal expansion, and the expansion is restrained by the arm portion 4 so that the portion is almost inflated. Do not (expand). Thereby, the diameter dimension R2 of the direction along the extending direction A of the arm part 4 of the rim | limb part 5 becomes substantially the same as the diameter dimension R1 of a normal temperature state.
On the other hand, in the rim portion 5, the deviation between the radial direction and the orientation direction of the reinforcing fibers S is large in the portion where the weight portion 6 is integrally formed and in the vicinity thereof (the portion indicated by the broken line β). For this reason, the portion of the rim portion 5 in which the weight portion 6 is integrally formed and the vicinity thereof (the portion indicated by the broken line β) have a relatively high coefficient of thermal expansion. It expands outward (expands diameter) along Thereby, the diameter dimension R3 of the direction along the extending direction B of the weight part 6 of the rim | limb part 5 becomes longer than the diameter dimension R1 of a normal temperature state.
As a result, when the temperature rises from room temperature, the rim portion 5 thermally expands into an elliptical shape in which the extending direction A of the arm portion 4 is the short axis direction and the extending direction B of the weight portion 6 is the long axis direction.

The weight portion 6 has a high coefficient of thermal expansion along the extending direction B, and greatly expands (extends) along the extending direction B. At this time, since the one end 6a is integrated with the rim portion 5, the weight portion 6 extends without being constrained to the inner side (side toward the center C) of the rim portion 5 with the one end 6a as a reference. As a result, the single center of gravity 6 b of the weight portion 6 is displaced to the inside of the rim portion 5.
In the first embodiment, the rim portion 5 thermally expands into an elliptical shape with the extending direction B of the weight portion 6 as the major axis direction, and thus the distance L2 in the radial direction from the center C to the gravity center 6b of the weight portion 6. Is substantially the same as the distance L1 in the normal temperature state.

  Thus, in the balance wheel 2 of Example 1, the expansion state of the balance wheel 2 when the temperature rises from room temperature can be grasped. Then, after grasping the expansion of the balance wheel 2, the deformation state of the balance wheel 2 is arbitrarily defined to appropriately control the change of the moment of inertia caused by the deformation of the balance wheel 2 with the temperature rise. be able to.

And in the time regulator for timepieces, generally, the Young's modulus of the hairspring decreases as the temperature rises, so the spring constant decreases. This reduction in the spring constant of the hairspring acts to increase the vibration cycle of the time governor, as is apparent from the above-described equation (1).
However, in the balance wheel 2 of the first embodiment, as described above, it is possible to appropriately control the change in the moment of inertia accompanying the temperature rise by arbitrarily defining the deformation state of the balance wheel 2. On the other hand, a decrease in the Young's modulus (spring constant) of the hairspring can be grasped in advance by experiments or the like. Therefore, in the time governor 10 for the timepiece according to the first embodiment, the time governor for the timepiece is controlled by appropriately controlling the change in the moment of inertia of the balance wheel 2 based on the decrease in the spring constant of the balance spring when the temperature rises. It is possible to control the change of the ten vibration cycles, and to suppress the decrease in the accuracy of the rate due to the temperature change.

  In the first embodiment, the weight portion 6 is supported by the rim portion 5 and extends along the radial direction with the balance 3 as the center. Therefore, the rim portion 5 expands (expands) into an elliptical shape with the extending direction B of the weight portion 6 as the major axis direction, while the weight portion 6 expands (extends) so that the center of gravity 6b moves to the center C side. To do. In addition, since the arm part 4 hardly expands at the time of temperature rise, there is almost no influence on the movement of the center-of-gravity position of the balance wheel 2 as a whole. Therefore, the movement of the center of gravity of the balance wheel 2 can be suppressed by the movement of the center of gravity due to the expansion of the rim 5 and the movement of the center of gravity due to the expansion of the weight 6.

  And when temperature rises from normal temperature in this way, since the fluctuation | variation of the gravity center position of the balance wheel 2 is suppressed, the balance wheel 2 is equipped with the positive thermal expansion coefficient (property which expands by temperature rise). However, when the temperature rises, the moment of inertia of the balance wheel 2 is suppressed from increasing, and the balance wheel 2 does not act to increase the vibration period of the time governor 10. For this reason, in the first embodiment, even when the spring constant of the hairspring 1 is lowered as the temperature rises, the movement of the center of gravity position is suppressed in the balance wheel 2 as described above, and the change of the moment of inertia (Increase) can be suppressed. Accordingly, it is possible to suppress an increase in the vibration period of the timepiece governing device 10 when the temperature rises, as compared to a general timepiece governing device.

  Moreover, in the first embodiment, the weight portion 6 is formed of fiber reinforced plastic, and the extending direction B of the weight portion 6 is in the extending direction A of the arm portion 4 and the orientation direction of the reinforcing fibers S. Vertical direction (direction orthogonal).

Therefore, the weight portion 6 is formed at the most deformed (expanded) position, and the change in the center of gravity due to the expansion of the rim portion 5 is efficiently suppressed, and further, the length of the weight portion 6 is reduced. By appropriately setting, it is possible to reduce the moment of inertia of the balance wheel 2 when the temperature rises.
As a result, it is possible to suppress a change in the vibration period of the time governor 10 for a timepiece, and to further suppress a decrease in accuracy of the rate due to a temperature change.

  And in this Example 1, the arm part 4, the rim | limb part 5, and the weight part 6 which comprise the balance wheel 2 are integrally molded with the fiber reinforced plastics. Therefore, there is no need to assemble these parts, and the manufacturing process can be simplified. In addition, the positional accuracy of each part can be improved and the temperature characteristics can be stabilized as compared with the case of forming by assembly.

(Modification)
The balance wheel 2 of the first embodiment has a pair of weight portions 6 extending in a direction orthogonal to the extending direction A of the arm portion 4 and the orientation direction of the reinforcing fibers S. However, the present invention is not limited to this, and a balance wheel that includes the arm portion 4 and the rim portion 5 and does not have a weight portion, such as a balance wheel 2A shown in FIG.
Even in this case, the state of thermal expansion of the balance wheel 2 can be grasped by setting the orientation direction of the reinforcing fibers S in a direction parallel to the extending direction A of the arm portion 4. The change of the moment of inertia when the temperature of the wheel 2 rises can be appropriately controlled.

Further, in the balance wheel 2 of the first embodiment, the extending direction A of the pair of arms 4 b and 4 c coincides with the diameter direction of the rim portion 5. However, the present invention is not limited to this. The arm part 4 should just have the through-hole 4a which the balance stem 3 fits in, and the arm part extended to the outer side of this balance stem 3 from the balance stem 3, and at least arm part 4 is fiber reinforced plastics. And the orientation direction of the reinforcing fiber S may be set in a direction parallel to the extending direction A of the arm portion 4.
Therefore, for example, the arm part is composed of three or more arms and is formed by a member different from the rim part, and the three or more arms are extended at equal angular intervals in the radial direction centering on the balance 3. May be present. At this time, the state of thermal expansion of the arm portion can be grasped by setting the orientation direction of the reinforcing fibers S in a direction parallel to the extending direction of each arm.

  In the first embodiment described above, the weight portion 6 has a uniform shape in the length direction. However, the weight portion 6 is not limited to a uniform shape, and the width or width increases toward the inside of the rim portion 5. It is also possible to adopt a shape in which the thickness increases due to the increase in thickness. As described above, according to the weight portion whose weight increases toward the inner side of the rim portion 5, the amount of movement of the center of gravity position to the inner side of the rim portion 5 due to the rise in temperature is set to a uniform width and thickness. It can be made larger than the amount of movement of the center of gravity by the weight portion.

  Furthermore, in Example 1, although the fiber reinforced plastic which forms the balance wheel 2 showed the example which is a unidirectional material (UD material) with which the reinforced fiber was orientated in one direction, it is not restricted to this. It may be a cloth material in which reinforcing fibers are oriented in two directions, both vertically and horizontally, by weaving reinforcing fibers vertically and horizontally. Even in this case, the thermal expansion coefficient of the arm part is suppressed by setting the fiber direction of any one of the reinforcing fibers oriented vertically and horizontally in a direction parallel to the extending direction of the arm part. Thus, the deformation state of the balance wheel can be grasped. And the change of the moment of inertia of the balance wheel when the temperature rises can be controlled.

  In addition, when providing the weight part 6 when forming the balance wheel 2 using the fiber reinforced plastic using the reinforcing fibers S oriented vertically and horizontally, the angle of the weight part 6 orthogonal to the arm part 5 or any fiber direction In addition, the amount of deformation of the weight portion 6 due to the temperature can be set as appropriate by arranging at an angle that does not follow the above. For example, as shown in FIG. 6, by arranging the weight portion 6 so as to be an intermediate angle between the vertical and horizontal reinforcing fibers S, the weight portion 6 is formed at an angle along one of the fiber directions. The amount of deformation due to the temperature of the weight portion 6 can be increased. Of course, it is good also as a structure which combined the weight part 6 of the angle along the direction of a reinforced fiber, and the weight part 6 of the angle which does not follow the direction of a reinforced fiber.

In the example described above, the temperature rises. When the temperature falls, the rim portion 5 extends in the extending direction A of the arm portion 4 in the balance wheel 2 as opposed to the temperature rise. The shaft 6 is deformed into an elliptical shape having the extending direction B of the weight portion 6 as a short axis. On the other hand, the weight portion 6 is reduced along the extending direction B with the one end 6 a integrated with the rim portion 5 as a reference. The arm portion 4 is hardly deformed.
Thus, even when the temperature is lowered, the deformation state of the balance wheel can be grasped, and the change in the inertia moment of the balance wheel when the temperature is lowered can be appropriately controlled.

DESCRIPTION OF SYMBOLS 10 Time regulating device 1 Timepiece spring 2 Balance wheel 3 Spring stem 4 Arm part 4a Through hole 4b, 4c Arm 5 Rim part 6 Weight part

Claims (5)

A balance, and an arm extending from the balance to the outside of the balance, and a rim that is supported by the arm and extends in an arc shape along a circumferential direction centering on the balance,
The balance wheel is formed of a fiber reinforced plastic having reinforcing fibers, and the orientation direction of the reinforcing fibers is set in a direction parallel to the extending direction of the arm portions. . The balance wheel according to claim 1, further comprising a weight portion that is supported by the rim portion and extends along a radial direction centering on the balance stem. The weight portion is formed of the fiber reinforced plastic, and the extending direction of the weight portion is set to a direction perpendicular to the extending direction of the arm portion and the orientation direction of the reinforcing fibers. The balance wheel according to claim 2, wherein: The balance wheel according to claim 2 or 3, wherein the arm portion, the rim portion, and the weight portion are integrally formed of the fiber reinforced plastic. A speed governing device for a timepiece, comprising: a hairspring and the balance wheel according to any one of claims 1 to 4.