JP6808799B2 - Speed governor for balance wheels and watches - Google Patents

Description

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

In a mechanical timepiece, it is necessary to precisely adjust the accuracy of the vibration cycle of the speed governor (temple) in order to obtain an accurate rate (degree of delay and advance of the timepiece). This speed governor has a balance wheel and a balance spring, and the vibration period is represented by the following equation (1).

Here, T: Vibration period of the balance
I: Moment of inertia of the balance wheel
K: The spring constant of the hairspring.
That is, the vibration period of the speed governor changes depending on the moment of inertia around the center of rotation of the balance wheel and the spring constant of the whiskers.

Here, a material that expands due to an increase in temperature is generally used for the balance wheel. Therefore, when the temperature rises, the diameter of the balance wheel expands, increasing the moment of inertia. In addition, a material whose Young's modulus decreases as the temperature rises is generally used for the hairspring. Therefore, 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 whiskers decreases. Therefore, the vibration cycle of the governor generally becomes shorter at low temperatures and longer 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, See Patent Document 1).

Special Table 2007-533973

Here, it is known that fiber reinforced plastics generally have a lower coefficient of thermal expansion than synthetic resins containing no reinforcing fibers. Therefore, by forming the balance with fiber reinforced plastic, it is possible to suppress the expansion of the balance when the temperature rises.
However, even when the balance sheet is formed of fiber reinforced plastic, it is difficult to grasp the expanded state of the balance wheel caused by the temperature rise simply by using the fiber reinforced plastic. Therefore, it was not possible to properly control the moment of inertia of the balance wheel when the temperature rises.

The present invention has been made by paying attention to the above problems, and is used for a balance wheel and a timepiece capable of appropriately controlling the change of the moment of inertia of the balance wheel due to the temperature change and suppressing the decrease in the accuracy of the rate due to the temperature change. It is an object of the present invention to provide a speed governor.

In order to achieve the above object, the present invention presents the present invention along the balance, the arm portion extending from the balance to the outside of the balance, and the arm portion supported by the arm portion along the circumferential direction centered on the balance. It is provided with a rim portion extending in an arc shape, is supported by the rim portion, and has a weight portion extending along the radial direction centered on the balance, and the weight portion contains reinforcing fibers oriented in the vertical and horizontal directions. It is formed of the fiber reinforced plastic used and the weight portion is arranged at an angle not along the fiber direction of the reinforcing fiber.

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 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 clock speed governor of Example 1. FIG. It is a top view which shows the balance wheel of the speed governor for a timepiece of Example 1. FIG. It is a top view of the balance wheel of Example 1 in a room temperature state. It is a top view of the balance wheel of Example 1 in a high temperature state. It is a top view which shows the modification of the balance wheel of the speed governor for a timepiece of Example 1. FIG. It is a top view which shows the further modification of the balance wheel of the speed governor for a timepiece of Example 1. FIG.

Hereinafter, embodiments for implementing the balance wheel and watch speed governor of the present invention will be described with reference to Example 1 shown in the drawings.

(Example 1)
[Structure of speed governor for balance wheel and watch]
FIG. 1 is a perspective view showing a clock speed governor of the first embodiment. FIG. 2 is a plan view showing the balance wheel of the first embodiment. Hereinafter, the configuration of the balance wheel and the speed governor for the timepiece of the first embodiment will be described with reference to FIGS. 1 and 2.

The watch speed governor (temple) 10 of the first embodiment is built in a portable watch (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 hairspring that is spirally wound in one plane, and the inner end is joined to the balance spring 3 of the balance wheel 2, and the outer end is the balance of the movement of a portable watch. It is fixed to the 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 wheel 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 the main plate of the movement of the portable watch and the balance sheet (both not shown).

The arm portion 4 is formed with a through hole 4a into which the balance shaft 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) about the balance stem 3 have. The pair of arms 4b and 4c extend in opposite directions with the through hole 4a in between, 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 stem 3.

The rim portion 5 extends in an arc shape along the circumferential direction centered on the balance stem 3, and has a circular ring shape without a break 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, respectively.
Here, in a state where the arm portion 4 and the rim portion 5 are connected, 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. That is, 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 pillar shape, and one end 6a of the extending direction (axial direction) B of the weight portion 6 is integrated with the rim portion 5, and the radial direction (radiation) centered on the balance with hairspring 3 is formed. Along the direction), it extends inward of the rim portion 5. Here, a pair of weight portions 6 are provided at target positions with the balance shaft 3 in between, and the extending direction B is orthogonal to the extending direction A of the arm portion 4 (vertical 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 constrained inside the rim portion 5 in the radial direction with reference to one end 6a integrated with the rim portion 5. It expands and contracts.

Then, in the first embodiment, the arm portion 4, the rim portion 5, and the weight portion 6 are integrally molded with fiber reinforced plastic.
Here, "fiber reinforced plastic" is a prepreg sheet formed by impregnating a woven resin made by impregnating a synthetic resin as a main raw material with a woven fabric produced while keeping the reinforcing fibers oriented (in the state of long fibers). , A plastic composite material with increased strength of synthetic resin. Since the fibers are directional, the coefficient of thermal expansion and strength become anisotropic depending on the orientation of the fibers. That is, this fiber reinforced plastic has a low coefficient of thermal expansion in the direction along the direction of the fibers (parallel direction) and a high coefficient of thermal expansion in the direction orthogonal to the direction of the fibers (vertical direction). Then, in this Example 1, a unidirectional material (UD material) in which the reinforcing fibers are oriented in one direction is used.
Further, "integral molding" is to integrally mold the product at the same time as joining the members without using secondary bonding or mechanical joining, and the arm portion 4, the rim portion 5, and the weight portion 6 At the same time as joining, each part is formed. Here, the balance wheel 2 is formed by punching a plate-shaped fiber reinforced plastic formed by laminating prepreg sheets with a mold.

As the reinforcing fiber used for the fiber reinforced plastic, carbon fiber, glass fiber, boron fiber, aramid fiber, polyethylene fiber and the like can be used. Further, as the synthetic resin which is the main raw material of the 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 is used. You may.

Then, in the first embodiment, as shown in FIG. 2, the orientation direction of the reinforcing fibers S of the fiber reinforced plastic is parallel to the extending direction A of the arm portion 4 (the axial direction of the arm portion 4). It is set to (direction along the extension direction A). Further, in the first embodiment, since the extending direction B of the weight portion 6 is orthogonal to the extending direction A of the arm portion 4, the orientation direction of the reinforcing fibers S is the extending direction B of the weight portion 6 ( It is set in a direction perpendicular to the axial direction of the weight portion 6.

[Action of speed governor for balance wheel and watch]
FIG. 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, the operation of the balance wheel and the speed governor for the timepiece of the first embodiment will be described with reference to FIGS. 3 and 4.

As shown in FIG. 3, the balance wheel 2 of the first embodiment has a rim portion 5 having a diameter dimension centered on the center C in a substantially perfect circular state at room temperature (before deformation in response to a temperature change). Further, the center of gravity 6b of the weight portion 6 alone is located at a distance L1 in the radial direction from the center C. Here, "normal temperature" refers to a temperature range of about 20 ° C ± 5 ° C.

The balance wheel 2 of the first embodiment has a temperature characteristic (property of expansion due to a temperature rise) in which the coefficient of thermal expansion is positive. On the other hand, the fiber reinforced plastic forming the balance wheel 2 has the lowest coefficient of thermal expansion in the direction along the orientation direction of the reinforcing fibers S, and the coefficient of thermal expansion increases as the deviation from the orientation direction of the reinforcing fibers S increases. It becomes higher, and 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, as shown in FIG. 4, the arm portion 4 hardly expands (extends) because the coefficient of thermal expansion along the extending direction A is low.

On the other hand, the rim portion 5 expands (diameters) outward in the radial direction centered on the center C, but the portion where the tips 4d and 4e of the arm portion 4 are connected and the portion in 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 portion 4 hardly expands (extends). Therefore, of the rim portion 5, the portion to which the arm portion 4 is connected and the portion in 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 to almost expand. Do not (expand the diameter). As a result, the diameter dimension R2 of the arm portion 4 of the rim portion 5 in the direction along the extending direction A becomes substantially the same as the diameter dimension R1 in the normal temperature state.
On the other hand, in the portion of the rim portion 5 in which the weight portion 6 is integrally formed and the portion in the vicinity thereof (the portion indicated by the broken line β), the difference between the radial direction and the orientation direction of the reinforcing fibers S is large. Therefore, in the rim portion 5, the portion in which the weight portion 6 is integrally formed and the portion in the vicinity thereof (the portion indicated by the broken line β) have a relatively high coefficient of thermal expansion, and therefore, in the radial direction centered on the center C. It expands (diameters) outward along the line. As a result, the diameter dimension R3 of the weight portion 6 of the rim portion 5 in the direction along the extending direction B becomes longer than the diameter dimension R1 in the normal temperature state.
As a result, when the temperature of the rim portion 5 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 minor 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 one end 6a is integrated with the rim portion 5, the weight portion 6 extends without being restricted to the inside of the rim portion 5 (the side toward the center C) with reference to the one end 6a. As a result, the center of gravity 6b of the single body of the weight portion 6 is displaced inward of the rim portion 5.
In the first embodiment, since 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, the radial distance L2 from the center C to the center of gravity 6b of the weight portion 6 Is almost the same as the distance L1 at room temperature.

In this way, in the balance wheel 2 of the first embodiment, it is possible to grasp the expanded state of the balance wheel 2 when the temperature rises from room temperature. Then, after grasping the expansion of the balance wheel 2, by arbitrarily defining the deformation state of the balance wheel 2, the change in the moment of inertia due to the deformation of the balance wheel 2 with the temperature rise is appropriately controlled. be able to.

In a watch speed governor, the Young's modulus of the hairspring generally decreases as the temperature rises, so that the spring constant decreases. As is clear from the above equation (1), this decrease in the spring constant of the hairspring acts to prolong the vibration cycle of the clock speed governor.
However, in the balance wheel 2 of the first embodiment, as described above, the change of the moment of inertia due to the temperature rise can be appropriately controlled by arbitrarily defining the deformed state of the balance wheel 2. On the other hand, the decrease in Young's modulus (spring constant) of the hairspring can be grasped in advance by experiments or the like. Therefore, in the watch speed governor 10 of the first embodiment, the change of the moment of inertia of the balance wheel 2 is appropriately controlled based on the decrease of the spring constant of the whiskers when the temperature rises, so that the watch speed governor 10 is used. The change in the vibration cycle of 10 can be controlled, and the decrease in the accuracy of the moment of inertia due to the temperature change can be suppressed.

Further, in the first embodiment, the weight portion 6 is supported by the rim portion 5 and extends along the radial direction about the balance with hairspring 3. Therefore, the rim portion 5 expands (expands) in 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 toward the center C. To do. Since the arm portion 4 hardly expands when the temperature rises, there is almost no influence on the movement of the position of the center of gravity of the entire balance wheel 2. Therefore, the movement of the center of gravity due to the expansion of the rim portion 5 and the movement of the center of gravity due to the expansion of the weight portion 6 can suppress the fluctuation of the position of the center of gravity of the entire balance wheel 2.

Then, when the temperature rises from room temperature in this way, the fluctuation of the position of the center of gravity of the entire balance wheel 2 is suppressed, so that the balance wheel 2 has a positive coefficient of thermal expansion (property of expansion due to the temperature rise). However, when the temperature rises, the moment of inertia of the balance wheel 2 is suppressed from becoming large, and the balance wheel 2 does not act to lengthen the vibration cycle of the clock speed governor 10. Therefore, in the first embodiment, even when the spring constant of the hairspring 1 decreases as the temperature rises, the movement of the center of gravity position is suppressed in the balance wheel 2 as described above, and the moment of inertia changes. (Increase) can be suppressed. As a result, it is possible to suppress the vibration cycle of the watch speed governor 10 from becoming longer when the temperature rises, as compared with a general watch speed governor.

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

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

Then, in the first embodiment, the arm portion 4, the rim portion 5, and the weight portion 6 constituting the balance wheel 2 are integrally molded with fiber reinforced plastic. Therefore, the process of assembling each of these parts is not required, and the manufacturing process can be simplified. In addition, the position accuracy of each part can be improved and the temperature characteristics can be stabilized as compared with the case of forming by assembling.

(Modification example)
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 may be a balance wheel composed of an arm portion 4 and a rim portion 5 and having no weight portion, for example, as in the balance wheel 2A shown in FIG.
Even in this case, 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 state of thermal expansion of the balance wheel 2 can be grasped, and the balance wheel 2 can be grasped. It is possible to appropriately control the change in the moment of inertia when the temperature of the wheel 2 rises.

Further, in the balance wheel 2 of the first embodiment, the extending direction A of the pair of arms 4b and 4c coincides with the diameter direction of the rim portion 5. However, it is not limited to this. The arm portion 4 may have a through hole 4a into which the balance plate 3 is fitted and an arm portion extending from the balance plate 3 to the outside of the balance plate 3, and at least the arm portion 4 is made of fiber reinforced plastic. The orientation direction of the reinforcing fibers S may be set in a direction parallel to the extending direction A of the arm portion 4.
Therefore, for example, the arm portion is composed of three or more arms and is formed by a member separate from the rim portion, and the three or more arms are extended at equal angular intervals in the radial direction centered on the balance stem 3. May be present. At this time, by setting the orientation direction of the reinforcing fibers S in a direction parallel to the extending direction of each arm, the state of thermal expansion of the arm portion can be grasped.

Then, in the above-described first embodiment, the weight portion 6 has a uniform shape in the length direction, but the shape is not limited to the uniform shape, and the width becomes wider or the thickness increases toward the inside of the rim portion 5. It is also possible to adopt a shape in which the weight becomes heavier due to the thickening of the rim. As described above, according to the weight portion having a shape in which the weight increases toward the inside of the rim portion 5, the amount of the center of gravity moving to the inside of the rim portion 5 due to the increase in temperature has a uniform width and thickness. It can be made larger than the amount of movement of the center of gravity position by the weight portion.

Further, in Example 1, the fiber reinforced plastic forming the balance wheel 2 is an example of a unidirectional material (UD material) in which the reinforcing fibers are oriented in one direction, but the present invention is not limited to this. By weaving the reinforcing fibers in the vertical and horizontal directions, a cloth material in which the reinforcing fibers are oriented in two directions in the vertical and horizontal directions may be used. Even in this case, the coefficient of thermal expansion of the arm portion is suppressed by setting the fiber direction of one of the reinforcing fibers oriented vertically and horizontally in a direction parallel to the extending direction of the arm portion. However, it is possible to grasp the deformed state of the balance wheel. Then, it is possible to control the change in the moment of inertia of the balance wheel when the temperature rises.

When the weight portion 6 is provided when the balance wheel 2 is formed by using the fiber reinforced plastic using the reinforcing fibers S oriented in the vertical and horizontal directions, the weight portion 6 is at an angle orthogonal to the arm portion 5 or in any fiber direction. By arranging the weight portion 6 at an angle that does not follow the above, it is possible to appropriately set the amount of deformation of the weight portion 6 due to the temperature. For example, as shown in FIG. 6, by arranging the weight portion 6 so as to be at an angle intermediate between the angles of the vertical and horizontal reinforcing fibers S, the weight portion 6 is formed at an angle along any of the fiber directions. , The amount of deformation of the weight portion 6 due to temperature can be increased. As a matter of course, the weight portion 6 having an angle along the direction of the reinforcing fibers and the weight portion 6 having an angle not following the direction of the reinforcing fibers may be combined.

The example described above is the case where the temperature rises, but when the temperature falls, contrary to the case where the temperature rises, in the balance wheel 2, the rim portion 5 lengthens the extending direction A of the arm portion 4. It is deformed into an elliptical shape with the extending direction B of the weight portion 6 as the axis and the minor axis. On the other hand, the weight portion 6 is reduced along the extending direction B with reference to one end 6a integrated with the rim portion 5. The arm portion 4 is hardly deformed.
In this way, even when the temperature drops, the deformed state of the balance wheel can be grasped, and the change in the moment of inertia of the balance wheel when the temperature drops can be appropriately controlled.

10 Clock speed governor 1 Hairspring 2 Balance wheel 3 Balance wheel 4 Arm part 4a Through hole 4b, 4c Arm 5 Rim part 6 Weight part

Claims (4)

It is provided with a balance, an arm portion extending from the balance to the outside of the balance, and a rim portion supported by the arm and extending in an arc shape along the circumferential direction centered on the balance.
It has a weight portion that is supported by the rim portion and extends along the radial direction about the balance center.
The weight portion is formed of a fiber reinforced plastic using reinforcing fibers oriented in the vertical and horizontal directions, and the weight portion is arranged at an angle not along the fiber direction of the reinforcing fibers. The balance wheel according to claim 1 , wherein the weight portion is arranged at an angle intermediate between the angles of the reinforcing fibers oriented in the vertical and horizontal directions of the fiber reinforced plastic. The balance wheel according to claim 1 or 2 , wherein the arm portion, the rim portion, and the weight portion are integrally molded with a fiber reinforced plastic using reinforcing fibers oriented in the vertical and horizontal directions. .. A clock speed governor comprising a hairspring and a balance wheel according to any one of claims 1 to 3 .