JPH0535346Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Technical field of invention] This idea concerns the second wheel of a clock.

[Prior art and its problems] In general, pointer-type watches transmit the rotation of a drive source such as a step motor to pointers such as hour and minute hands through a gear train mechanism, and display the time by moving the hands. The second wheel is equipped with a slip mechanism to prevent the second hand and step motor from rotating when setting the hands such as when adjusting the time.

That is, the second wheel integrally includes a gear part and a shaft part having a cylinder pinion, and during normal hand movement, the gear part and shaft part rotate together to move the minute hand, and to adjust the hands for time adjustment, etc. When the torque (load) exceeds a certain level
When applied to the cylindrical pinion of the shaft, only the shaft rotates, causing the minute and hour hands to rotate, while the second hand and step motor do not rotate.

Conventionally, in such a slip mechanism, the gear part and the shaft part of the second wheel are made of metal, and a pair of elastic pieces in the form of leaf springs are provided on the metal gear part, and these pair of elastic pieces are used to push the shaft part. The tube pinion is held elastically. Therefore, the number of parts is large, assembly workability is complicated, stable slip torque cannot be obtained, and since it is made of metal, machining is troublesome and costs are high.

[Purpose of the invention] This invention was made in view of the above-mentioned circumstances, and its purpose is to have a simple structure, a small number of parts, excellent assembly workability, and be able to be manufactured at low cost. To provide a second wheel for a watch that can provide stable rotation and moderate and stable slip torque.

[Main points of the invention] In order to achieve the above-mentioned purpose, this invention is made by integrally molding a gear part with a synthetic resin different from the shaft part onto a synthetic resin shaft part having a cylindrical pinion part so as to be able to slip and rotate. In addition to making the center wheel, a protrusion is formed on the shaft that protrudes in a direction perpendicular to the axial direction, one surface on the axial side of this protrusion is formed into a plane parallel to the perpendicular direction, and the other surface is formed into a plane parallel to the perpendicular direction. The surface is formed into an inclined surface that is inclined with respect to the perpendicular direction when moving from the tip of one surface toward the center, and a recessed portion having a horizontal surface that contacts the horizontal surface of the protrusion and an inclined surface that contacts the inclined surface of the protrusion is formed in the gear part. The main point is that.

[Example] Hereinafter, an example in which this invention is applied to an electronic wristwatch will be described with reference to FIGS. 1 to 5.

Configuration Figure 1 shows the analog movement of an electronic wristwatch. This analog movement transmits the rotation of the step motor 1 to the gear train mechanism 2.
The time is indicated and displayed by moving the hands of the clock 3a, minute hand 3b, second hand 3c, etc., and the hands of the hands are adjusted by the time adjustment mechanism.

The step motor 1 is a drive source for moving the hands, and is composed of a rotor 5, a stator (not shown), a coil, etc., and is configured such that the rotor 5 rotates in steps of 180 degrees each time a reversal pulse of a fixed period is applied to the coil. It's getting old. In this case, the rotor 5 consists of a rotor portion 5a, a rotor pinion 5b, a rotor shaft 5c, etc., as shown in FIG. A ring 5d is attached to the rotor shaft 5c, and a rotor shaft 5c is rotatably attached between the base plate 6 and the gear train bridge 7.

The wheel train mechanism 2 transmits the rotation of the step motor 1 to the pointer to move the pointer. Consists of a car 13, etc., a main plate 6 and a gear train bridge 7
An intermediate wheel 8, a fourth wheel & pinion 9, and a third wheel & pinion 10 are installed between the main plate 6, and a center wheel & pinion 11, a hour wheel & pinion 12, and an hour wheel & pinion 13 are installed on the main plate 6, respectively. in this case,
The main plate 6 and the gear train bridge 7 are made of polyphenylene sulfide resin (hereinafter referred to as "PPS") containing glass fibers.
A dial plate 14 is provided on the top of the main plate 6.

Each car will be explained in turn below.

The intermediate wheel 8 is the rotor pinion 5b of the step motor 1.
It is made of polyacetal resin with potassium titanate whiskers and rotates by meshing with the
It is integrally formed with the shaft portion 8a and the intermediate pinion 8b.

The fourth wheel 9 rotates by meshing with the intermediate pinion 8b of the intermediate wheel 8, and moves the second hand 3c, whose shaft portion 9a forms the second hand axis, and the bearing portion 6a of the main plate 6.
The second hand 3c protrudes upward through the dial plate 14, and this protruding portion serves as a hand attachment portion 9c, and the second hand 3c is attached to this hand attachment portion 9c. The fourth wheel 9 is made of liquid crystal polymer resin containing potassium titanate whiskers, and is formed integrally with the shaft portion 9a and the fourth pinion 9b.

The third wheel 10 rotates by meshing with the fourth pinion 9b of the fourth wheel 9, and is made of polyacetal resin containing potassium titanate whiskers.
a and the third pinion 10b. In this case, the third pinion 10b penetrates the base plate 6 and protrudes above it.

The second wheel 11 rotates while meshing with the third pinion 10b of the third wheel 10, and moves the minute hand 3b.The shaft portion 11a forms the minute hand shaft, and is rotatable around the outer periphery of the bearing portion 6a of the main plate 6. The upper end of the shaft portion 11a protrudes upward through the dial 14, and the minute hand 3b is attached to this protruding portion. This center wheel 11 is formed by integrally molding a shaft portion 11a having a cylindrical pinion portion 11b and a gear portion 11c in two colors so as to be able to rotate by slipping.
a contains potassium titanate whisker which has high wear resistance and strength and has a higher melting temperature than gear part 11c
The gear part 11c is made of PPS resin, and the gear part 11c is made of 12 nylon resin containing potassium titanate whiskers, which has a small shrinkage rate and has a lower melting temperature than the shaft part 11a.

The center wheel & pinion 11 is constructed as shown in FIG. That is, the shaft part 11a has a cylindrical shape, and a cylindrical pinion part 11b is formed at the lower part of the shaft part 11a.
The inside of 1b is a large diameter part a, and a pinion b, a protrusion c, and an extension part d are formed on the outer periphery of the large diameter part a. Further, the upper side of the shaft portion 11a has a small diameter portion e inside.
It has a relief part f and a needle attachment part g formed on its outer periphery. The cylindrical pinion part 11b is the large diameter part a
is adapted to rotatably fit on the outer periphery of the bearing portion 6a of the base plate 6, and an extending portion d at the lower end thereof protrudes downward to form an annular recess formed around the bearing portion 6a of the base plate 6. The shaft portion 11a is rotatably inserted into the groove 6b, and is thereby held long enough to prevent the shaft portion 11a from wobbling. Further, the pinion b provided on the outer periphery is engaged with the teeth 12c of the hinoura wheel 12. The protruding part c is a part where the gear part 11c is integrally formed, and is formed in the shape of a flange on the lower side of the pinion b, and its outer peripheral part is an inclined surface that slopes downward.
c _a , and the lower surface of this protruding portion c serves as a mold mating surface for molding dies 15, 15, which will be described later. In this case, the outer diameter c ₁ of the tip of the protrusion c is approximately
2.1 mm, its thickness c ₂ is about 0.3 mm, and the tip angle α
is now 74°. The gear part 11c integrally molded on the protruding part c has an outer diameter of about 3.4 mm,
Thickness t ₁ that is thicker than the protrusion c and protrudes below it
is approximately 0.15 mm and bites into the protrusion c. As a result, the center wheel 11 has a moderate slip torque (3
~6g・cm), and more torque (load)
When the rotation is applied, the cylinder pinion part 11b (shaft part 11a) and the gear part 11c mutually slip and rotate.
Further, the small diameter portion e on the upper side of the shaft portion 11a is configured such that the shaft portion 9a of the fourth wheel & pinion 9 is inserted therein so as not to contact therewith. The relief part f formed on the outer periphery of the shaft part 11a is located at a part corresponding to the hand attachment part 13b of the hour wheel 13, and has a predetermined clearance therebetween, so that when the hour hand 3a is attached, the relief part f is located at a part corresponding to the hand attachment part 13b of the hour wheel 13.
Even if 3b is deformed, it will not come into contact with the shaft portion 11a of the center wheel & pinion 11. Note that the needle attachment portion g at the upper end is a portion into which the minute hand 3b is fitted.

When molding such a center wheel and pinion 11, molds 15 and 16 as shown in FIGS. 3A and 3B are used. is incorporated into.
Therefore, as shown in FIG. 3A, the shaft portion 11a having the cylindrical corner portion 11b is injection molded using a pair of upper and lower primary molding molds 15, 15. 15 is the parting line
PL, that is, the joint surface of the upper and lower molds 15, 15 is located on the lower surface of the protrusion c of the shaft portion 11a, so that the tip of the protrusion c due to the positional shift of the upper and lower molds 15, 15. This prevents eccentricity. The resin pellets used when molding the shaft portion 11a with such molds 15, 15 are PPS resin containing crystalline potassium titanate whiskers mixed with a few percent of silicone oil that is heat resistant to 250°C or higher. The resin injection gate G is provided on the upper end surface of the shaft portion 11a. Shaft portion 11a formed in this way
After being taken out from the primary molding molds 15, 15, it is placed in a pair of upper and lower secondary molding molds 16, 16 as shown in FIG. 3B, and the resin for secondary molding is placed underneath. Resin injection gate G provided in the side mold 16
Then, the gear portion 11c is integrally molded onto the shaft portion 11a, which is the primary molded product. As described above, the resin pellets used in this case are 12 nylon resin containing crystalline potassium titanate whiskers mixed with several percent of silicone oil that is heat resistant to 250° C. or higher. The molded product (center wheel 11) formed in this way has a dimethylsiloxane structure.
Oil annealing treatment is performed by immersing it in silicone oil at a high temperature of 100℃ for about 3 hours. In this case, it is sufficient that the temperature of the silicone oil is about 80% of the heat deformation temperature and for one hour or more. Then, the center wheel 11 as shown in FIG.
is obtained.

The hino-ura wheel 12 rotates by meshing with the pinion b formed on the cylindrical pinion portion 11b of the center wheel 11, and is made of polyacetal resin containing potassium titanate whiskers, and is integrated with the hino-ura pinion 12b. The shaft portion 6 is formed in a shape that protrudes from the upper surface of the base plate 6.
It is rotatably attached to c. in this case,
The Hinoura wheel 12 is held down from above by a Hinoura presser foot 12c.

The hour wheel 13 rotates by meshing with the pinion 12b of the hour wheel 12, and moves the hour hand 3a. It is made of polyacetal resin containing potassium titanate whiskers, and its shaft portion 13a is cylindrical. Rotatably mounted on the outer periphery of the shaft portion 11a of the car 11,
Its upper end protrudes above the dial 14, and this protruding portion serves as a hand attachment portion 13b, into which the hour hand 3a is attached by press fitting.

Next, the operation of the analog movement configured as above will be described.

Normally, a step motor 1 moves the hands to indicate and display the time. That is, as shown in FIG. 1, when the rotor 5 of the step motor 1 rotates,
The rotation is transmitted to the fourth wheel & pinion 9 via the intermediate wheel 8, and the fourth wheel & pinion 9 rotates to move the second hand 3c attached to the upper end of the shaft portion 9a of the fourth wheel & pinion 9. Further, when the fourth wheel & pinion 9 rotates in this manner, the rotation is transmitted to the center wheel & pinion 11 via the third wheel & pinion 10, and the center wheel & pinion 11 rotates. In this case, the shaft portion 11a and the gear portion 11c of the center wheel & pinion 11 are integrally formed to be capable of slip rotation.
1a and gear portion 11c rotate integrally. Therefore, the minute hand 3b attached to the shaft portion 11a of the center wheel & pinion 11 moves. When the center wheel 11 rotates in this manner, the rotation is transmitted to the hour wheel 13 via the hour wheel 12, and the hour wheel 13 rotates to move the hour hand 3a. In this manner, the hour hand 3a, minute hand 3b, and second hand 3c move above the dial 14, so that the time is indicated and displayed.

Further, when adjusting the time, it is sufficient to pull out the winding stem of the time adjustment mechanism (not shown) and turn it by a predetermined amount. Then, the second wheel 11 and hour wheel 13 rotate,
Hand alignment is performed by rotating the hour hand 3a and minute hand 3b. At this time, torque (rotational force) is applied to the center wheel & pinion 11 from the winding stem, but the torque (rotational force) from the winding stem causes the slip torque (3 to 3) of the center wheel & pinion 11.
6g・cm) or more, the shaft 11 of the second wheel & pinion 11
a and the gear part 11c, and the shaft part 11
a slips and rotates. Moreover, when the shaft portion 11a slips and rotates in this manner, a thin film of silicone oil is formed on the contact surface between the shaft portion 11a and the gear portion 11c, and this film acts as a lubricant.
The shaft portion 11a and the gear portion 11c are rotated smoothly with stable slip torque. Therefore, the hands can be set without rotating the second hand.

However, according to the second wheel 11 of the analog movement as described above, the gear part 11c is made of a synthetic resin different from the synthetic resin shaft part 11a having the cylindrical pinion part 11b, and the gear part 11c can slip and rotate on the protruding part c of the shaft part 11a. The tip of the protruding part c of the shaft part 11a is formed into a downwardly inclined inclined surface c _a , and the joint part between the shaft part 11a and the gear part 11c,
In other words, the lower surface of the protrusion c of the shaft portion 11a is connected to the shaft portion 11a.
Since the mold mating surface (parting line PL) of the molding molds 15, 15 is made as shown in FIG.
As a result, the tip of the protruding portion c of the shaft portion 11a does not become eccentric, so that it can be molded very well and a suitable and stable slip torque can be obtained. For example, if the tip of the protruding portion c of the shaft portion 11a is formed into a mountain shape, and the tip of the mountain shape is used as the mold mating surface of the upper and lower molds 15, 15, the misalignment between the upper and lower molds 15, 15 (this (occurs more or less without fail), the tip of the protrusion c is not symmetrical and is eccentric, so the slip torque between the shaft portion 11a and the gear portion 11c increases, making it impossible to obtain an appropriate and stable slip torque. However, according to the center wheel and pinion 11 as described above, the tip of the protruding portion c of the shaft portion 11a is formed into a downwardly inclined inclined surface c _a , and the lower surface thereof is formed with the mold matching surface of the molds 15, 15. By doing so, the upper and lower molds 15,
Even if the molds 15 are misaligned, the shaft portion 11a can be molded well, so alignment of the upper and lower molds 15, 15 can be extremely simple and easy. Therefore, the molds 15, 15 are easy to manufacture and can be manufactured at relatively low cost.

In the above-described embodiment, the tip of the protruding portion c of the shaft portion 11a is formed into a downwardly inclined inclined surface c _a , but this invention is not limited to this, and as shown in FIG. It may be formed on a vertical surface c _b with a degree of slope, or it may be formed on an inclined surface c _c having steps with different inclination angles, as shown in FIG. As shown in FIG. c, it may be formed into an overhanging slope c _d that slopes upward. In this case, the mold mating surfaces (parting line PL) of the upper and lower molds 15, 15 should be
The gear part 11c is located on the upper surface of the projection part c.
The bite is thick on the upper side of the protrusion c.
Moreover, this biting is not limited to the lower side or the upper side, but it is of course possible to bite both the upper and lower sides as shown in FIGS. 4a and 4d.

Further, in the embodiment described above, the shaft portion 1 of the center wheel & pinion 11
Potassium titanate whiskers were used as a reinforcing material for the resin used in 1a and gear part 11c.
This invention is not limited to these, and for example, glass fibers, carbon fibers, reduced potassium titanate whiskers, etc. may be used.

In addition, in the above embodiment, the shaft portion 11a is made of PPS resin containing potassium titanate whiskers, and the gear portion 11c is made of 12 nylon resin containing potassium titanate whiskers, so that the slip torque is approximately 3 to 6 g.
cm, but if you change these materials it will be 2~
It is possible to obtain a slip torque of 10 g cm.

Further, the second wheel & pinion 11 of the embodiment described above has the shaft portion 11
A and the gear part 11c are integrally molded to be slip rotatable and then dipped in silicone oil, but this invention is not limited to this. The product may be immersed in silicone oil having a dimethylsiloxane structure and annealed. In addition, the shaft portion 11a and the gear portion 11c
Although both of the two parts were molded using resin pellets mixed with a few percent of silicone oil, it is also possible to mold only one of them with resin pellets mixed with a few percent of silicone oil.
It is not necessarily necessary to mold resin pellets mixed with a few percent of silicone oil.

Furthermore, this invention is not limited to the above-mentioned electronic wristwatch, but can be widely applied to other pointer type watches.

[Effects of the invention] As explained in detail above, this invention provides a center wheel with a simple structure, a small number of parts, and excellent assembly workability, as well as the positioning of the mold when molding the shaft. It is possible to obtain a center wheel and pinion having extremely good rotational characteristics without eccentricity of the joint between the shaft portion and the gear portion due to misalignment, and having moderate and stable slip torque.

[Brief explanation of drawings]

Figures 1 to 3 show an example in which this invention is applied to an analog movement of an electronic wristwatch.
Figure 1 is a sectional view of the main part, Figure 2 is an enlarged sectional view of the center wheel, Figures 3 A and B are diagrams showing the manufacturing method of the center wheel, and Figures 4 a to d are the center wheel. It is a sectional view showing a modification. 11...Second wheel, 11a...Shaft portion, 11b...
Cylindrical pinion part, 11c...gear part.

Claims (1)

[Claims for Utility Model Registration] Consisting of a shaft made of synthetic resin having a cylindrical pinion part, and a gear part made of a synthetic resin different from the shaft and integrally molded onto the shaft so as to be able to slip and rotate, The shaft part has a protrusion that protrudes in a direction perpendicular to the axial direction, one surface of the protrusion on the axial side is formed into a plane parallel to the perpendicular direction, and the other surface is formed in a plane parallel to the perpendicular direction. is formed into an inclined surface that is inclined with respect to the perpendicular direction from the tip of the surface toward the center, and the gear portion has a horizontal surface that contacts a horizontal surface of the protruding portion of the shaft portion and an inclined surface of the protruding portion of the shaft portion. A second wheel for a timepiece, characterized in that a recess is formed that has a contacting inclined surface and engages with a protrusion of the shaft.