Gear assembly and timepiece

Abstract

A gear assembly is characterized by being provided with: a shaft body having a gear; and a cylindrical member into which the shaft body is inserted, the shaft body and the cylindrical member being in contact in the axial direction via a gasket having a hardness higher than that of the cylindrical member.

Description

Technical Field

[0001] The present disclosure relates to a gear assembly and a timepiece. Background Art

[0002] In a gear train mechanism of a mechanical timepiece, as disclosed in Japanese Patent Application Laid-Open No. 2020-30092, for example, a shaft of a fourth wheel or the like that moves a hand is in surface contact with a support member such as a center tube in the axial direction and is supported by the support member. Summary of the invention

[0003] A gear assembly according to one aspect of the present disclosure is characterized by comprising:

[0004] a shaft having a gear; and

[0005] a cylindrical member into which the shaft body is inserted,

[0006] The shaft body and the cylindrical member are in contact in the axial direction via a spacer having a higher hardness than the cylindrical member.

[0007] A timepiece according to another aspect of the present disclosure is characterized by comprising:

[0008] A gear train mechanism comprising a gear assembly, the gear assembly having a shaft having a gear and a cylindrical member into which the shaft is inserted, the shaft and the cylindrical member being in contact in the axial direction via a gasket having a higher hardness than the cylindrical member; and

[0009] A housing accommodates the gear train mechanism.

[0010] Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings). BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a front view showing the main part of the timepiece according to the embodiment.

[0012] Figure 2 It is a cross-sectional view of the main parts around the second wheel & pinion of the timepiece according to the embodiment.

[0013] Figure 3 This is an enlarged view of the upper half of the second wheel & pinion according to the embodiment. DETAILED DESCRIPTION

[0014] An embodiment of the present invention will be described with reference to the drawings.

[0015] In addition, in the embodiment described below, various limitations that are technically preferable for carrying out the present invention are given, but the scope of the present invention is not limited to the following embodiment and illustrations.

[0016] [Overall structure of the watch]

[0017] Figure 1 1 is a front view showing the main parts of the timepiece 100 according to the present embodiment. Figure 1 In order to facilitate understanding of the structure of the main parts, the illustration of a dial or a part of the main board 21 is omitted.

[0018] like Figure 1 As shown, the timepiece 100 according to the present embodiment is an analog timepiece that displays time using a plurality of hands 3 (second hand 3s, minute hand 3m, hour hand 3h) indicating a time scale 102. The timepiece 100 includes a main body case 101 formed in a short cylindrical shape when viewed from the front.

[0019] A plurality of hands 3 , a plurality of drive mechanisms 30 for individually driving the plurality of hands 3 to rotate, and the like are accommodated inside the main body case 101 .

[0020] The plurality of drive mechanisms 30 include a second hand drive mechanism 30s that rotationally drives the second hand 3s, a minute hand drive mechanism 30m that rotationally drives the minute hand 3m, and an hour hand drive mechanism 30h that rotationally drives the hour hand 3h.

[0021] Each driving mechanism 30 includes a motor 32 as a driving source and a wheel train mechanism 33 that transmits the driving force of the motor 32 to the hands 3. Specifically, the second hand driving mechanism 30s includes a first motor 32s and a first wheel train mechanism 33s, the minute hand driving mechanism 30m includes a second motor 32m and a second wheel train mechanism 33m, and the hour hand driving mechanism 30h includes a third motor 32h and a third wheel train mechanism 33h.

[0022] Each gear train mechanism 33 includes a plurality of gear assemblies 40 .

[0023] For example, the first wheel train mechanism 33s of the second hand drive mechanism 30s includes a gear assembly 40 such as the fourth wheel (second hand wheel). The second wheel train mechanism 33m of the minute hand drive mechanism 30m includes a gear assembly 40 such as the second wheel (minute hand wheel). The third wheel train mechanism 33h of the hour hand drive mechanism 30h includes a gear assembly 40 such as the intermediate wheel or barrel wheel (hour hand wheel).

[0024] In addition, the gear train mechanism 33 may include gears other than the gear assembly 40. The gear in this case only needs to include at least a gear and a shaft. The gear and the shaft may be separate components, or they may be integrated.

[0025] [Gear assembly configuration]

[0026] Hereinafter, as an example of the gear assembly 40 according to the present embodiment, the configuration of the center wheel & pinion 40A will be described by way of example.

[0027] Figure 2 4 is a cross-sectional view of the main parts around the fourth wheel 40A of the timepiece 100. Figure 2 In order to facilitate understanding of the structure of the main parts, a part of the third wheel train mechanism 33h of the hour hand drive mechanism 30h (such as the intermediate wheel or the barrel wheel) is omitted from the illustration.

[0028] As shown in the figure, the second wheel & pinion 40A includes a shaft body 41 , a gear (spur gear) 42 , and a cylindrical member (center tube) 43 .

[0029] Hereinafter, the front-back direction of the timepiece 100 is referred to as the up-down direction, wherein the front side ( Figure 2 and Figure 3 The lower side) is called the "lower side", and the back side ( Figure 2 and Figure 3 The upper side of the shaft body 41 is referred to as the “upper side”. In addition, the direction perpendicular to the central axis Ax of the shaft body 41 along the up-down direction is referred to as the “radial direction”, and the rotation direction around the central axis Ax is referred to as the “circumferential direction”.

[0030] The shaft body 41 is, for example, a shaft component of carbon tool steel (SK material), and is arranged in the up-down direction. The shaft body 41 is supported by the wheel train support 22 and the second support 23 in a manner that it can rotate around the central axis Ax. The wheel train support 22 is arranged on the upper side of the main plate (bottom plate) 21, and supports the upper end of the shaft body 41. The second support 23 is arranged between the main plate 21 and the wheel train support 22, and supports the portion of the shaft body 41 that is slightly above the upper and lower centers via the cylindrical member 43.

[0031] A second hand 3s is fixed to the lower end of the shaft body 41 .

[0032] The gear 42 is a spur gear made of silicon, for example, and is mounted on the upper portion of the shaft 41. More specifically, the gear 42 is bonded to the upper surface of the large diameter portion 41a formed on the upper portion of the shaft 41. However, the material and fixing structure of the gear 42 are not particularly limited.

[0033] The gear 42 is urged downward by a washer 45 disposed between the gear 42 and the train wheel support 22 on the upper side.

[0034] The gear 42 meshes with the fourth intermediate wheel 46 connected to the first motor 32s. Thus, the rotational force of the first motor 32s is transmitted to the fourth wheel 40A, and the second hand 3s at the lower end of the shaft 41 rotates.

[0035] The cylindrical member 43 is a substantially cylindrical member inserted into the lower half of the shaft 41 except the lower end thereof and arranged coaxially with the shaft 41. The cylindrical member 43 is made of a material softer than the shaft 41 (eg, stainless steel, brass, nickel, etc.).

[0036] The cylindrical member 43 has a large-diameter fixing portion 43a having a flange portion at the upper end. The cylindrical member 43 is fixed to the second support member 23 by press-fitting the fixing portion 43a into the second support member 23 from above and caulking (fastening).

[0037] The center wheel & pinion 50 of the minute hand driving mechanism 30 m (second wheel train mechanism 33 m ) is coaxially arranged on the cylindrical member 43 .

[0038] The center wheel & pinion 50 includes a cylindrical center wheel & pinion main body (shaft body) 51 and a center gear 52 .

[0039] The center wheel & pinion main body 51 is rotatably supported by the main plate 21. The shaft 41 and the cylindrical member 43 are inserted through the center wheel & pinion main body 51, and the shaft 41 is exposed from the lower end of the center wheel & pinion main body 51. The minute hand 3m is fixed to the lower end of the center wheel & pinion main body 51.

[0040] The second gear 52 is a spur gear made of silicon, for example, and is fixed to the upper portion of the second wheel and pinion body 51. The second gear 52 is urged downward by a washer 55 disposed between the second gear 52 and the second support 23 on the upper side.

[0041] The second gear 52 meshes with the second intermediate wheel 56 connected to the second motor 32m. Thus, the rotational force of the second motor 32m is transmitted to the second wheel 50, and the minute hand 3m at the lower end of the second wheel body 51 rotates.

[0042] Figure 3 This is an enlarged view of the upper half of the second wheel & pinion 40A.

[0043] As shown in the figure, the upper end of the cylindrical member 43 is in surface contact with the shaft body 41 in the axial direction (vertical direction) via a spacer 44 made of silicon having a higher hardness than the cylindrical member 43 .

[0044] Specifically, a cylindrical counterbore 43 b opened upward is formed on the upper surface of the fixing portion 43 a of the cylindrical member 43 , and the gasket 44 is accommodated (fitted) in the counterbore 43 b .

[0045] An escape groove 43c is formed at the corner of the outer diameter side of the bottom surface of the counterbore 43b. The escape groove 43c of the present embodiment is formed in a shape in which the outer diameter end of the bottom surface of the counterbore 43b is recessed downward, that is, it is formed in a manner that becomes deeper (downward) in the axial direction (up and down direction). However, the escape groove 43c can be any shape as long as it can escape (avoid contact) the corner of the outer diameter lower side of the gasket 44. For example, it can also be a shape that escapes to the outer diameter side or the outer diameter obliquely downward side.

[0046] The spacer 44 is formed into a circular ring shape corresponding to the counterbore 43b by photolithography, for example. The inner diameter and outer diameter of the spacer 44 are formed to have a required contact area between the spacer 44 and the seat surface (the lower surface of the large diameter portion 41a) of the shaft body 41. In addition, the inner diameter of the spacer 44 is formed to have a sufficient gap between the spacer 44 and the shaft body 41 to avoid contact.

[0047] The gasket 44 is bonded to the counterbore 43 b of the cylindrical member 43 by an adhesive.

[0048] In addition, the gasket 44 may be arranged in the counterbore 43b before the cylindrical member 43 is riveted to the second support 23. Thus, when the cylindrical member 43 is riveted, the inner peripheral surface of the counterbore 43b shrinks, so that the gasket 44 can be properly fixed in the counterbore 43b. That is, the gasket 44 is fixed in the counterbore 43b by riveting the fixing portion 43a (the end portion of the cylindrical member 43 on the side having the counterbore 43b) with the gasket 44 accommodated in the counterbore 43b.

[0049] In addition, a relief groove 41b is formed at the corner of the inner diameter side of the lower surface of the large diameter portion 41a in the shaft body 41 that contacts the gasket 44. The relief groove 41b of this embodiment is set in a shape in which the inner diameter end of the lower surface of the large diameter portion 41a is recessed toward the inner diameter side, that is, it is set to become deeper in the direction intersecting the axis of the shaft body 41. However, the relief groove 41b can be any shape as long as it can avoid (avoid contact with) the corner of the inner diameter upper side of the gasket 44. For example, it can also be a shape that avoids upward or obliquely upward to the inner diameter.

[0050] [Technical Effects of the Present Embodiment]

[0051] As described above, according to the present embodiment, the shaft body 41 and the cylindrical member 43 are in contact in the axial direction via the spacer 44 having a higher hardness than the cylindrical member 43 .

[0052] In the wheel train mechanism of the mechanical clock disclosed in the above-mentioned Japanese Patent Publication No. 2020-30092, when the friction between the shaft body and the supporting member is large, the energy required for the needle to move increases, and wear powder may be generated and the product life becomes shorter. However, since the present embodiment has the above-mentioned structure, the friction between the cylindrical member 43 and the shaft body 41 when the needle is moving can be reduced compared to the case where the cylindrical member 43 and the shaft body 41 are in direct contact. Therefore, the shaft body 41 having the gear 42 can be appropriately supported.

[0053] Furthermore, by reducing the friction of the shaft 41 when the needle is running, the energy required for the needle to run can be reduced, and the generation of wear powder can be suppressed. That is, energy saving and long life of the product can be achieved. In addition, since the backlash can be reduced, the position accuracy of the pointer 3 is improved.

[0054] Here, in order to improve the running accuracy of the second hand 3s, the washer 45 is arranged between the wheel train support 22 and the gear 42 for the purpose of braking the second wheel 40A. As described above, by adopting the structure of this embodiment, the position accuracy of the pointer 3 is improved, so the washer 45 that plays a common role may be set to a structure without using the washer 45. In this case, the effect of being able to reduce the number of parts is obtained.

[0055] In addition, it is also possible to replace the cylindrical member 43 itself with a hard material without using the liner 44. However, the cylindrical member 43 has a complicated shape in order to avoid contact with the shaft 41 of the second wheel 40A or the second wheel body 51. Therefore, when the cylindrical member 43 is made of a hard material, not only processing becomes difficult, but also riveting to the second support 23 becomes difficult. By using the liner 44, the above-mentioned effect can be obtained more easily than by replacing the cylindrical member 43 itself with a hard material.

[0056] Furthermore, according to the present embodiment, the gasket 44 is accommodated (fitted) in the counterbore 43 b formed in the upper end surface of the cylindrical member 43 .

[0057] Compared with the case where the cylindrical member 43 directly supports the shaft 41, the increase in the vertical length due to the insertion of the gasket 44 can be avoided, and the thickness of the timepiece 100 can be maintained at the same level. In addition, the gasket 44 can be appropriately positioned in the vertical direction and radial direction by the counterbore 43b.

[0058] Furthermore, according to the present embodiment, in the cylindrical member 43 , the escape groove 43 c is provided at the corner portion on the outer diameter side of the bottom surface of the counterbore 43 b .

[0059] Thereby, the gasket 44 can be appropriately held in the counterbore 43 b.

[0060] That is, since the gasket 44 made of silicon is very hard and is produced by photolithography, when stress is concentrated, not only is the corner easily damaged, but it is also difficult to chamfer the corner. Therefore, it is not desirable to form an angle R at the corner of the bottom surface of the countersunk hole 43b that may interfere with (contact) the gasket 44 during installation. However, in the usual cutting process, it is unavoidable to form the angle R at the corner. Therefore, the angle R is removed and the avoidance groove 43c is provided by performing additional cutting on the corner of the countersunk hole 43b of the tubular member 43. In this way, the interference between the gasket 44 and the countersunk hole 43b during installation can be avoided. In this way, the positioning of the gasket 44 does not become difficult due to reducing the gasket 44 to avoid the angle R, and the gasket 44 can be properly held by the countersunk hole 43b.

[0061] In addition, the direction of the escape groove 43c is preferably the up-down direction (axial direction) consistent with the processing direction of the counterbore 43b. In order to set the direction of the escape groove 43c to the radial direction, it is necessary to perform an undercut relative to the processing direction of the counterbore 43b. On the other hand, by setting the processing direction of the escape groove 43c to the axial direction, the escape groove 43c can be formed relatively easily by cutting.

[0062] According to the present embodiment, the gasket 44 is bonded to the cylindrical member 43 by an adhesive. That is, the escape groove 43c on the bottom surface of the counterbore 43b can be used as a reservoir groove for the adhesive.

[0063] This allows the adhesive to be appropriately retained in the counterbore 43b, and it is possible to suppress the excess adhesive from overflowing from the counterbore 43b. Furthermore, it is possible to suppress the occurrence of malfunctions caused by the adhesive overflowing from the counterbore 43b.

[0064] Furthermore, according to the present embodiment, the shaft body 41 is provided with the escape groove 41 b at the corner portion on the inner diameter side of the surface that contacts the spacer 44 .

[0065] This can suppress the corner portion of the spacer 44 from being damaged due to the corner portion contacting the shaft body 41 .

[0066] In addition, according to the present embodiment, the spacer 44 is made of silicon.

[0067] That is, by using the spacer 44 made of silicon with high lubricity, the friction of the shaft 41 during the needle movement can be further reduced.

[0068] [other]

[0069] In addition, the embodiment to which the present invention can be applied is not limited to the above-mentioned embodiment, and various modifications can be made without departing from the scope of the present invention.

[0070] For example, in the above-mentioned embodiment, the pad 44 supporting the shaft 41 is made of silicon having a lattice plane. However, the material (raw material) of the pad 44 is not limited to silicon as long as it has a higher hardness than the cylindrical member 43. For example, a wafer made of diamond can also be used as the material having a lattice plane.

[0071] The material of the shaft body 41 is not limited to carbon tool steel (SK material), and any metal with high hardness may be used. The cylindrical member 43 may be made of any metal with lower hardness than the shaft body 41 .

[0072] In the above embodiment, the cylindrical member 43 and the shaft body 41 are provided with escape grooves to avoid contact with the gasket 44. However, the escape grooves may be provided at positions facing the corners of the gasket 44 in at least one of the cylindrical member 43 and the shaft body 41.

[0073] In addition, in the above-mentioned embodiment, the fourth wheel is cited as an example of the gear assembly involved in the present invention. However, the gear assembly involved in the present invention can also be applied to a gear assembly other than the fourth wheel in the gear train mechanism. For example, it can also be applied to a gear train mechanism of a time hand other than the second hand, and it can also be applied to a gear train mechanism of a function hand that displays various functions other than the time.

[0074] Furthermore, the gear assembly of the present invention is not limited to the gear assembly used in the wheel train mechanism of a clock, but can be widely applied to the gear assembly having a structure in which a cylindrical member (member having a hole) supports a shaft having a gear. In particular, it can be applied to a small gear mechanism that is difficult to adopt a complex bearing structure.

[0075] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

[0076] This application claims the benefit of Japanese Patent Application No. 2023-159313, filed September 25, 2023, which is hereby incorporated by reference herein in its entirety.

Claims

1. A gear assembly, characterized in that: have: a shaft having a gear; and a cylindrical member into which the shaft body is inserted, The shaft body and the cylindrical member are in contact in the axial direction via a spacer having a higher hardness than the cylindrical member.

2. The gear assembly according to claim 1, wherein: The cylindrical member has a countersunk hole on the axial end surface. The gasket is received in the counterbore.

3. The gear assembly according to claim 2, wherein: In the cylindrical member, the escape groove is provided at a corner portion on the outer diameter side of the bottom surface of the counterbore.

4. The gear assembly according to claim 3, wherein: The escape groove of the cylindrical member is provided so as to become deeper in the axial direction of the shaft body.

5. The gear assembly according to claim 1, wherein: The shaft body is provided with the escape groove at a corner portion on the inner diameter side of a surface that contacts the spacer.

6. The gear assembly according to claim 5, wherein: The escape groove of the shaft body is provided so as to become deeper in a direction intersecting the axis of the shaft body.

7. The gear assembly according to any one of claims 1 to 6, wherein: The gasket is made of silicon.

8. The gear assembly according to claim 7, wherein: The shaft is made of high-hardness metal. The cylindrical member is made of a metal having a lower hardness than the shaft body.

9. The gear assembly according to claim 2, wherein: The gasket is made of silicon, The gasket is fixed to the counterbore by caulking the end portion of the cylindrical member on the side having the counterbore in a state where the gasket is accommodated in the counterbore.

10. The gear assembly according to claim 9, wherein: The shaft is made of high-hardness metal. The cylindrical member is made of a metal having a lower hardness than the shaft body.

11. A timepiece, characterized in that: have: A gear train mechanism comprising the gear assembly according to claim 1; and A housing accommodates the gear train mechanism.

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