JP2009204575A - Gear structure and timepiece - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gear structure for transmitting high torque, without relative rotation between a gear and a shaft occurring, and to provide a timepiece having this. <P>SOLUTION: This gear structure comprises the gear 11, and the shaft 21 pressed in a gear hole 31 formed in the center part of the gear 11. The gear 11 has three or more projections 4, projecting at the center direction of the gear hole 31, the projections 4 or the shaft 21 is deformed by pressing in of the shaft 21, and the gear 11 and the shaft 21 are fixed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a gear structure suitable for use in a small precision machine such as a timepiece and a timepiece having the same.

The gear structure is composed of a shaft portion and a gear portion, and the shaft is press-fitted into a hole formed in the gear, so that the gear and the shaft are fixed without relative rotation (for example, Patent Documents). 1).
As a first conventional example, the shape of the press-fit portion is a gear hole portion, a shaft press-fit portion, and the outer shape are all circular, and the press-fit portion is press-fitted so that the shaft rotation shaft and the gear rotation shaft overlap. is there.
Also, the diameter of the portion that interferes with the gear hole when the shaft is press-fitted and the diameter of the gear hole have a diameter that is an interference fit, and the portion that interferes with the gear hole and the gear when the shaft is press-fitted The frictional force generated between the holes prevents the shaft and the gear from rotating relatively when torque is generated.

A gear structure as a second conventional example has a non-circular outer shape of the shaft press-fitting portion with respect to a circular shape of the gear hole portion. As a typical example of this structure, the outer shape of the axial press-fit portion has a shape having a plurality of convex portions and concave portions alternately, and passes through a circumscribed circle passing through the tips of the convex portions and the bottom of the concave portions. A gear structure in which a gear having a hole smaller in diameter than the circumscribed circle and larger in diameter than the inscribed circle is fitted to the inscribed circle, and the rotating shaft of the shaft and the rotating shaft of the gear overlap (for example, a patent) Reference 2).
When this gear structure is fitted to the gear and the shaft, the portion that interferes with the shaft convex portion of the gear hole is deformed so as to be larger than the gear hole diameter before fitting. A part is deformed so as to form a convex portion and enter the concave portion of the shaft while being smaller than the gear hole diameter before fitting into the concave portion of the shaft. In this way, the convex part of the gear hole formed by the convex part of the shaft by fitting with the concave part formed on the shaft is fitted by the convex part of the shaft by fitting with the convex part formed on the shaft. The formed recesses of the gear holes engage and transmit torque, so that not only the frictional force generated between the shaft and the gear but also the engagement of the unevenness makes it stronger against the torque difference generated between the gear and the shaft. It becomes possible to conclude to. Therefore, torque can be transmitted from the gear hole shown first and the shape of the shaft press-fitted into the gear hole being circular.
JP 2006-234437 A JP-A-11-194177

  In each of the conventional gear structures shown above, the first conventional example having a circular gear hole shape and a circular shaft press-fitting portion outer shape satisfies a predetermined function as the gear structure. Therefore, it takes time and effort to manage the tightening allowance, that is, to manage the outer diameter of the shaft press-fitting portion with respect to the gear hole diameter. This is because when the tightening margin is large, that is, when the outer diameter of the shaft press-fitting portion is larger than a predetermined dimension with respect to the gear hole diameter, the gear warps due to the stress generated in the gear due to the tightening margin when the shaft is press-fitted into the gear. As a result, there is a problem that friction loss occurs due to the gears coming into contact with other parts, and torque transmission cannot be normally performed. On the contrary, when the tightening margin is small, that is, when the outer diameter of the shaft press-fitting portion is smaller than a predetermined dimension with respect to the gear hole diameter, the friction force between the shaft and the gear hole is not sufficiently obtained and the shaft and the gear are There is a problem that slipping occurs. In order not to cause such a problem, the tightening allowance management by the management of the outer diameter of the shaft press-fitting portion and the gear hole diameter is required, and there is a problem that the management takes time.

In addition, in the case of the second conventional example in which the outer shape of the shaft press-fitting portion is a non-circular shape with respect to the circular shape of the gear hole portion, it passes through the convex tip of the concavo-convex portion formed in the shaft press-fitting portion. By making the diameter of the circumscribed circle larger than the diameter of the gear hole to be bent, the tip end portion having a diameter larger than the gear hole diameter of the convex portion formed in the shaft press-fitting portion is changed to the gear hole portion when fitted. It is deformed into a concave shape and is press-fitted into the gear hole. For this reason, the gear tip formed by deforming the gear hole is fitted into the recess formed on the shaft, so that the gear hole convex formed by the shaft convex is formed on the shaft. The concave part of the gear hole formed by the convex part of the shaft by fitting with the convex part is not only the frictional force generated in both rotation directions when engaging and generating torque, but also the convex part formed in the gear hole. Torque can be transmitted to each other by the surface formed perpendicular to the rotational direction by fitting the front end of the convex portion of the shaft and the shaft. By doing so, it is possible to tighten more firmly against the torque difference generated between the gear and the shaft.
However, since the convex part is formed by directly processing the shaft, the strength is reduced with respect to the torque generated in the rotation direction of the shaft concave part adjacent to the shaft, and a large torque is generated on the shaft. Since the torque cannot be withstood, the convex portion of the shaft is deformed, and there is a problem that a large torque cannot be transmitted.
SUMMARY OF THE INVENTION An object of the present invention is to provide a gear structure capable of transmitting high torque without causing relative rotation between a gear and a shaft, and a timepiece including the gear structure.

  The gear structure includes a gear and a shaft that is press-fitted into a gear hole formed in a central portion of the gear, and the gear has three or more protrusions that are convex toward the center of the gear hole. And the protrusion or the shaft is deformed by press-fitting the shaft so that the gear and the shaft are fixed.

According to the present invention, according to the above configuration, it is possible to provide a gear structure capable of transmitting high torque without causing relative rotation between the gear and the shaft, and a timepiece including the gear structure.

(1) Outline of the embodiment The conventional press-fitting portion has a circular shape when both the gear hole portion and the outer shape of the shaft press-fitting portion are circular, and the press-fitted so that the rotation shaft of the shaft and the rotation shaft of the gear overlap. When the is applied, only the frictional force generated at the contact surface between the shaft and the gear hole prevents the shaft and the gear from rotating relative to each other. It is very difficult to perform processing so that the shape of the shaft press-fitting portion and the gear hole press-fitted into the shaft press-fit portion are surely matched on the contact surface. Therefore, even if the shaft is press-fitted into the gear hole, slippage occurs between the contact surfaces of the gear hole and the shaft press-fitting portion, or when the shaft is press-fitted into the gear hole, the shaft diameter is set against the gear hole diameter. Therefore, the gear is warped in the axial direction, and the tooth tip does not mesh with the adjacent gear, so that the torque cannot be sufficiently transmitted.

  In addition, in the case where the outer shape of the shaft press-fit portion is a non-circular shape with respect to the circular shape of the gear hole portion, the strength of the processed portion is reduced by making the shaft press-fit portion non-circular, When a large torque is generated in the processed portion, the processed portion cannot withstand the torque and breaks.

  Therefore, in the present invention (without directly processing the shaft press-fitting portion), a plurality of protrusions protruding in the direction of the rotation center are formed in the gear hole. Further, three or more protrusions are formed in the gear hole so that the rotation center of the shaft and the rotation center of the gear coincide with each other. When the shaft is press-fitted into the gear hole in which the protrusion is formed in this way, the tip of the protrusion formed in the gear hole has a shaft plane shape on the shaft, and each protrusion presses toward the center. Fixed.

When the shaft is press-fitted into the gear hole, the protrusion formed on the gear hole needs to be press-fitted so that the gear center and the shaft center are at the same position. Therefore, the interval between the protrusions formed on the gear hole is such that when the shaft press-fit portion receives a force from each protrusion formed on the gear hole toward the shaft center, the force is in contact with the other through the shaft. The intervals at which the protrusions are formed are formed at equal intervals on the gear holes so that the hole protrusions are evenly distributed. However, this is not limited as long as the shaft and the gear center are on the same point and the shaft and the gear do not rotate relative to each other when torque is applied to the gear structure in the rotational direction.
In addition, when the shaft is press-fitted into the gear hole, the diameter of the circle formed by the tip of the protrusion formed by the tip of the protrusion is larger than the diameter of the shaft press-fitting portion at the protrusion and the shaft press-fitted portion formed in the gear hole. Since it is small, the shaft press-fit portion is deformed from the tip end portion of the projection formed in the gear hole toward the shaft center. At this time, deformation in the same degree as the width of the protrusions also occurs in the gear rotation direction. If the deformation at this time overlaps with the deformed portion due to the adjacent protrusion, the gear hole between the two protrusions also deforms in the axial center direction, and the tip of the protrusion formed in the gear hole and the shaft A contact surface part with a press-fit part will decrease. Therefore, the engagement between the protrusion formed in the gear hole and the protrusion formed by press-fitting the shaft is reduced, and the shaft and gear are rotated in the rotational direction by the engagement between the shaft press-fitting portion and the gear hole. The pressing force will no longer occur. Therefore, the distance between the protrusions formed in the gear hole is such that the deformation part generated in the shaft press-fitting part does not interfere with the deformation part generated by the adjacent protrusion part formed in the gear hole. To do.
The length of the protrusion formed in the gear hole to the tip of the protrusion shall be such that when the shaft is press-fitted into the gear hole, the outer diameter of the press-fitted portion of the shaft does not contact the gear hole, and torque in the shaft rotation direction When the occurrence of this occurs, the length that does not cause relative rotation of an amount that affects the predetermined function of the shaft and the gear portion by the torque that the projection receives from the shaft press-fitting portion.
The shape of the protrusion formed in the gear hole is a shape that is convex toward the center of the gear, and the convex shape is a shaft that is press-fitted into the tip when the shaft is press-fitted into the gear hole. Any state with a tightening allowance is sufficient.
Examples of the shape of the convex portion include a trapezoidal shape, a circular shape, and a triangular shape. However, when the shaft is press-fitted, the shaft and the gear are deformed in the press-fitting direction and the rotational direction without causing relative rotation. This is not the case unless there is something to do.
(2) Details of Embodiments Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.
(Embodiment 1)
FIG. 1 is an explanatory view showing a shaft and gears according to Embodiment 1 of the present invention.

  The gear structure 100 is composed of two bodies, a gear 11 and a shaft 21. A gear hole 31 for press-fitting the shaft 21 is opened at the center of the gear 11. The gear hole 31 is formed with a protrusion 4 that is convex in the center direction of the gear 11. The protruding portion 4 has a substantially circular shape, and a portion where the protruding portion 4 is in contact with the press-fitted shaft 2 is defined as a vertex portion 41. The plurality of protrusions 4 having the same shape are arranged at equal intervals in the circumferential direction of the hole on the gear hole.

Here, the assembly of the gear structure will be described below. First, the shaft 21 is press-fitted into the gear hole 31 in which the protrusion 4 is formed. The shaft 21 is press-fitted in a state where the shaft is pressed toward the center of rotation from the apex portion 41 of the protrusion 4. At this time, the diameter of the press-fitted portion of the shaft 21 is larger than the diameter of the tip circle formed by connecting the apex portion 41 in the portion (press-fitted portion) that comes into contact with the protrusion 4 and the shaft 21 by press-fitting. Therefore, in the tightening margin portion that is larger than the diameter of the tip circle formed by connecting the vertex portion 41, the vertex portion 41 is press-fitted by deforming the shaft 21 that is press-fitted at the contact portion with the shaft 21 in the axial center direction. Will be.
In addition, the protrusion 4 forms an uneven portion in the shaft press-fitting portion of the gear hole 31, so that when torque is applied to the shaft 21 or the gear 11 in the rotational direction, the gear between the shaft 21 and the gear 11 is When the unevenness formed in the hole 31 and the unevenness formed in the gear hole 31 are press-fitted, the unevenness formed in the shaft 21 meshes so that the transmission of torque between the gear and the shaft is press-fitted. Not only the frictional force generated between the gear hole 31 and the shaft 21 as in the case where the gear hole portion 31 and the outer shape of the shaft press-fit portion are circular, but also the shape of the portion is formed in the gear hole 31 and the shaft press-fit portion. The torque generated on the surface perpendicular to the rotation direction of the uneven portion is pressed between the protrusion 4 directly in the gear hole 31 and the protrusion formed on the shaft press-fitting portion, so that torque is transmitted without relative rotation. It becomes possible to do.

In the present embodiment described above, the number of protrusions is three in FIG. 1, but when the shaft is press-fitted into the gear hole where the convex portion is formed, the shaft and the gear do not rotate relative to each other, and the Any number may be formed as long as torque can be generated. Further, the shape of the convex portion is not limited as long as it is a convex shape from the gear hole toward the center of the gear, and the shape does not change when the shaft is press-fitted.
(Embodiment 2)
FIG. 2 is an explanatory view showing a shaft and gears according to Embodiment 2 of the present invention.

In the gear structure 200 according to the second embodiment, protrusions 5a and 5b are formed in the gear hole. The protrusions 5a and 5b are both configured from side surfaces having different lengths. The short surface portion 52 of one protrusion 5 a is formed so as to be substantially perpendicular to the surface of the gear hole 32. The long surface portion 51 of the other protrusion 5a is formed at a position obtained by rotating the short surface portion 52 by 45 degrees in the clockwise direction a about the intersection of the both surface portions 51 and 52.
On the other hand, the protruding portion 5 b is formed such that the short surface portion 53 is substantially perpendicular to the inner surface of the gear hole 32. The long surface portion 54 of the protruding portion 5b is formed at a position obtained by rotating the short surface portion 53 by 45 degrees counterclockwise b about the intersection of the both surface portions 53 and 54.

In the above-described embodiment, the long surface portions 51 and 54 are formed at positions rotated by 45 degrees with respect to the short surface portion, respectively. However, the shaft and the gear are not press-fitted without relative rotation. This is not the case.
When the shafts of the projecting portions 5a and 5b formed in this way are respectively press-fitted, 5a is pushed into the axial center direction c by the projecting portion 5a when the shaft 22 receives torque in the direction a. The short surface portion 52 is in surface contact with the surface perpendicular to the rotation direction. As a result, the shaft 22 and the gear 12 can directly generate torque in the rotational direction, and even if a force larger than the static friction force generated between the shaft 22 and the gear hole 32 is generated, the shaft 22 and the gear 12 rotate relative to each other. Torque can be generated without any problems. As for the protrusion 5b, when the shaft 22 receives torque in the b direction, torque can be generated in the same manner. Thus, in order to suppress the relative rotation in both the a direction and the b direction, both protrusions 5a and 5b are required. However, in order to suppress relative rotation in only one direction, it is only necessary to form three or more protrusions of only 5a or 5b in the gear hole 32.
When forming both the projecting portions 5a and 5b, the installation interval is deformed in the gear center direction c when the apex portion 55 of the projecting portion 5a contacts the shaft 22. At this time, the shaft is deformed with a width not only in the central direction but also in the rotational direction. The shaft 22 is similarly deformed in the gear center direction c because the apex portion 56 of the projecting portion 5 b adjacent to the projecting portion 5 a comes into contact with the shaft 22. If this deformation width interferes with the deformation portion by the adjacent protrusion, the deformation portion in the gear center direction by the vertex portion 55 and the deformation portion by the vertex portion 56 interfere, and the vertex portion 55 is counterclockwise in the b direction. In 56, there is no portion to be fitted to the shaft 22 in the clockwise a direction. Therefore, it is assumed that the protrusions 5a and 5b are installed at an interval that does not interfere with the two deformed portions.

Moreover, in this embodiment mentioned above, these protrusion parts 5a and 5b are made into one set, and two or more sets shall be formed in a gear hole at substantially equal intervals on a gear hole circumference. However, this does not apply as long as torque can be transmitted without the shaft and gears rotating relative to each other.
(Embodiment 3)
FIG. 3 is an explanatory view showing a shaft and gears according to Embodiment 3 of the present invention.

In the gear structure 300 according to Embodiment 3, the protrusion 6 is formed in the gear hole. The protrusion 6 has a substantially trapezoidal shape, and both side surfaces thereof extend in the direction of the rotation center of the gear 13 by the same length. Further, similarly to the second embodiment, the protrusions 6 may be arranged at substantially equal intervals. The shaft 23 to be press-fitted by the upper bottom portion (axial contact surface portion) 61 is fixed. Compared with the protrusions 4, 5 a, and 5 b shown in FIGS. 1 and 2, the shaft 23 can be brought into contact with the press-fitted surface 23, so that the shaft 23 can be more stably fixed. Further, since the shaft 23 to be press-fitted is centered on the gear center A and the diameter of the shaft 23 to be press-fitted is larger than the circular diameter formed by the respective convex upper-bottom portions 61, At the contact portion with the shaft 23 to be press-fit, the shaft 23 is deformed into the shape of the tip of the protruding portion and press-fitted. As a result, torque can be generated without causing relative rotation because the shaft 23 and the gear hole 33 can directly generate torque in the rotation direction on the contact surface formed perpendicular to the rotation direction of the gear structure 300. I can do it.
(Other embodiments)
As shown in FIG. 4, the protrusions 5a and 5b and the protrusion 6 of the present embodiment described above may be formed on the same gear hole. Even if other shapes are formed on the same gear hole, the shaft and the gear do not rotate relative to each other, and the rotation center of the shaft and the gear does not shift and torque can be generated. .

It is explanatory drawing which shows the gear structure which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows the gear structure which concerns on Embodiment 2 of this invention. It is explanatory drawing which shows the gear structure which concerns on Embodiment 3 of this invention. It is explanatory drawing which shows the gear structure which concerns on other embodiment of this invention.

Explanation of symbols

4, 5a, 5b, 6 Protrusions 11, 12, 13, 14 Gears 21, 22, 23, 24 Shafts 31, 32, 33, 34 Gear holes 41, 55, 56 Vertex parts 51, 54 Long face parts 52, 53 Short Surface part 61 Upper bottom part (axial contact surface part)
100, 200, 300, 400 Gear structure a Clockwise b Counterclockwise c Axis center direction d Axis center reverse direction

Claims (5)

Gears,
A shaft that is press-fitted into a gear hole formed in the center of the gear,
The gear has three or more projections that are convex in the center direction of the gear hole, and the projection or the shaft is deformed by press-fitting the shaft to fix the gear and the shaft. Gear structure.   The gear structure according to claim 1, wherein the protrusions are spaced at substantially equal intervals.   When a shaft larger than the diameter of the tooth tip circle formed by connecting the tip of the protrusion and smaller than the diameter of the gear hole is press-fitted, the tip circle formed by connecting the tip of the protrusion deformed by press-fitting The gear structure according to claim 1 or 2, wherein a diameter is smaller than a diameter of the gear hole, and the shaft and the tip of the deformed protrusion are fitted.   Each of the protrusions includes a pair of line-symmetric protrusions, each of the pair of protrusions has a long surface portion and a short surface portion in the gear plane, and the short surface portion is configured to be substantially perpendicular to the inner surface of the gear hole. The gear structure according to any one of claims 1 to 3.   A timepiece comprising the gear structure according to claim 1.

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