Gear assembly and timepiece

Abstract

To suitably support a shaft having a gear.SOLUTION: A gear assembly 40 includes a shaft 41 having a gear 42, and a cylindrical member 43 to which the shaft 41 is inserted. The shaft 41 and the cylindrical member 43 are brought into contact with each other in an axial direction, through a washer 44 having hardness higher than that of the cylindrical member 43.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a gear assembly and a timepiece. [Background technology]

[0002] In the train wheel mechanism of a mechanical timepiece, a shaft such as a fourth wheel that operates the hands is supported by a support member such as a center tube in surface contact in the axial direction (see, for example, Patent Document 1). Therefore, if friction between the shaft and the support member is large, not only will the energy required to move the hands increase, but wear particles will be generated, which may shorten the product life. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-30092 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made in consideration of the above circumstances, and has an object to suitably support a shaft having a gear. [Means for solving the problem]

[0005] In order to achieve the above object, the present invention provides a gear assembly, a shaft having a gear; a cylindrical member into which the shaft is inserted; The shaft and the tubular member are in axial contact with each other via a washer having a harder hardness than the tubular member. Effect of the Invention

[0006] According to the present invention, a shaft having a gear can be supported in an appropriate manner. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a front view showing the main parts of the timepiece according to the embodiment. [Diagram 2] 4 is a cross-sectional view of the main part around the fourth wheel in the timepiece according to the embodiment. FIG. [Diagram 3] FIG. 4 is an enlarged view of the upper half of the second wheel & pinion according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An embodiment of the present invention will be described with reference to the drawings. In addition, the embodiments described below are subject to various limitations that are technically preferable for implementing the present invention, but the scope of the present invention is not limited to the following embodiments and illustrated examples.

[0009] [Overall clock configuration] Fig. 1 is a front view showing the main parts of a timepiece 100 according to this embodiment. Note that in Fig. 1, the dial and part of the main plate 21 are omitted in order to make the main structure easier to understand.

[0010] As shown in Fig. 1, the timepiece 100 according to this embodiment is an analog timepiece that displays time by using multiple hands 3 (second hand 3s, minute hand 3m, hour hand 3h) to point to hour characters 102. The timepiece 100 has a main body case 101 formed into a short cylindrical shape when viewed from the front. The main body case 101 accommodates a plurality of hands 3, a plurality of drive mechanisms 30 for driving and rotating the plurality of hands 3 individually, and the like.

[0011] The multiple drive mechanisms 30 include a second hand drive mechanism 30s that drives and rotates the second hand 3s, a minute hand drive mechanism 30m that drives and rotates the minute hand 3m, and an hour hand drive mechanism 30h that drives and rotates the hour hand 3h. Each drive mechanism 30 includes a motor 32 which is a drive source, and a gear train mechanism 33 which transmits the driving force of the motor 32 to the hands 3. Specifically, the second hand drive mechanism 30s includes a first motor 32s and a first gear train mechanism 33s, the minute hand drive mechanism 30m includes a second motor 32m and a second gear train mechanism 33m, and the hour hand drive mechanism 30h includes a third motor 32h and a third gear train mechanism 33h.

[0012] Each gear train mechanism 33 includes a plurality of gear assemblies 40 . For example, the first train wheel mechanism 33s of the second hand drive mechanism 30s includes a gear assembly 40 such as a second wheel (second hand wheel). The second train wheel mechanism 33m of the minute hand drive mechanism 30m includes a gear assembly 40 such as a center wheel (minute hand wheel). The third train wheel mechanism 33h of the hour hand drive mechanism 30h includes a gear assembly 40 such as a minute wheel and an hour wheel (hour hand wheel). The gear train mechanism 33 may include gears other than the gear assembly 40. In this case, the gears need only include at least a gear and a shaft. The gear and the shaft may be separate parts as long as they are integral with each other.

[0013] [Gear assembly configuration] Hereinafter, the configuration of the second wheel & pinion 40A will be described as an example of the gear assembly 40 according to this embodiment. Fig. 2 is a cross-sectional view of the main parts around the second wheel 40A of the timepiece 100. Note that in Fig. 2, in order to make it easier to understand the main structure, part of the third wheel train mechanism 33h of the hour hand drive mechanism 30h (such as the minute wheel and hour wheel) is not shown. As shown in this figure, the second wheel 40A includes a shaft 41, a gear 42, and a cylindrical member (center tube) 43. Hereinafter, the front-to-back direction of the timepiece 100 will be referred to as the up-down direction, with the front side (the lower side in Figs. 2 and 3) being referred to as the "lower side" and the rear side (the upper side in Figs. 2 and 3) being referred to as the "upper side." Additionally, the direction perpendicular to the central axis Ax of the shaft 41 along the up-down direction will be referred to as the "radial direction," and the rotational direction around the central axis Ax will be referred to as the "circumferential direction."

[0014] The shaft 41 is an axle component made of, for example, carbon tool steel (SK material), and is arranged along the vertical direction. The shaft 41 is supported by the train wheel bridge 22 and the second bridge 23 so as to be rotatable around the central axis Ax. The train wheel bridge 22 is arranged above the main plate (base plate) 21, and supports the upper end of the shaft 41. The second bridge 23 is arranged between the main plate 21 and the train wheel bridge 22, and supports a portion of the shaft 41 slightly above the vertical center via a cylindrical member 43. A second hand 3s is fixed to the lower end of the shaft 41.

[0015] Gear 42 is, for example, a spur gear made of silicon, and is attached to the upper part of shaft 41. More specifically, gear 42 is bonded to the upper surface of large diameter portion 41a formed on the upper part of shaft 41. However, the material and fixing structure of gear 42 are not particularly limited. The gear 42 is biased downward by a washer 45 disposed between the gear 42 and the upper wheel train holder 22 . The gear 42 meshes with a second intermediate wheel 46 connected to the first motor 32s. As a result, the rotational force of the first motor 32s is transmitted to the second wheel 40A, causing the second hand 3s at the lower end of the shaft 41 to rotate.

[0016] The tubular member 43 is a part having a substantially cylindrical shape, and is arranged coaxially with the shaft 41, with about the lower half of the shaft 41 excluding the lower end being inserted into the tubular member 43. The tubular member 43 is made of a material (such as stainless steel, brass, or nickel) that is softer than the shaft 41. The cylindrical member 43 has a large-diameter fixing portion 43a with a flange at its upper end. The fixing portion 43a is press-fitted into the second receiver 23 from above and crimped (swaged), thereby fixing the cylindrical member 43 to the second receiver 23.

[0017] In the cylindrical member 43, a center wheel 50 of the minute hand drive mechanism 30m (second wheel train mechanism 33m) is coaxially arranged. The center wheel & pinion 50 includes a cylindrical center wheel body (shaft) 51 and a center gear (gear) 52. The center wheel & pinion body 51 is rotatably supported by the main plate 21. The shaft 41 and the cylindrical member 43 are inserted into the center wheel & pinion body 51, and the shaft 41 is exposed from the lower end. A minute hand 3m is fixed to the lower end of the center wheel & pinion body 51. The second gear 52 is, for example, a spur gear made of silicon, and is fixed to the upper part of the second wheel body 51. The second gear 52 is biased downward by a washer 55 arranged between the second gear 52 and the second bridge 23 above it. The center gear 52 meshes with a center intermediate wheel 56 connected to the second motor 32m. As a result, the rotational force of the second motor 32m is transmitted to the center wheel & pinion 50, causing the minute hand 3m at the lower end of the center wheel & pinion main body 51 to rotate.

[0018] FIG. 3 is an enlarged view of the upper half of the second wheel & pinion 40A. As shown in this figure, the upper end of the cylindrical member 43 is in surface contact with the shaft 41 in the axial direction (up-down direction) via a washer 44 made of silicon, which has a harder property than the cylindrical member 43 . Specifically, a cylindrical countersunk hole 43b that opens upward is formed on the upper surface of the fixing portion 43a of the tubular member 43, and a washer 44 is housed (fitted) in the countersunk hole 43b. An escape groove 43c is formed at the outer diameter side corner of the bottom surface of the countersunk hole 43b. In this embodiment, the escape groove 43c is formed so that the outer diameter end of the bottom surface of the countersunk hole 43b is recessed downward, that is, so that it is deepened (downward) in the axial direction (up-down direction). However, the escape groove 43c may have any shape as long as it can escape (avoid contact with) the outer diameter lower corner of the washer 44. For example, it may have a shape that escapes to the outer diameter side or to the outer diameter diagonally downward.

[0019] The washer 44 is formed into an annular shape corresponding to the countersunk hole 43b, for example, by lithography. The inner and outer diameters of the washer 44 are formed to have a required contact area with the seat surface (the lower surface of the large diameter portion 41a) of the shaft 41. The inner diameter of the washer 44 is formed to have a sufficient gap between the washer 44 and the shaft 41 to avoid contact. The washer 44 is bonded to the inside of the countersunk hole 43b of the cylindrical member 43 with an adhesive. The washer 44 may be placed in the countersunk hole 43b before the cylindrical member 43 is crimped to the second receiver 23. This allows the inner circumferential surface of the countersunk hole 43b to shrink when the cylindrical member 43 is crimped, so that the washer 44 can be suitably fixed in the countersunk hole 43b. That is, with the washer 44 housed in the countersunk hole 43b, the fixing portion 43a (the end of the cylindrical member 43 on the side having the countersunk hole 43b) is crimped and fixed in the countersunk hole 43b.

[0020] In addition, an escape groove 41b is formed in a corner on the inner diameter side of the lower surface of the large diameter portion 41a of the shaft 41, which contacts the washer 44. The escape groove 41b in this embodiment is provided so that the inner diameter end of the lower surface of the large diameter portion 41a is recessed toward the inner diameter side, that is, so that it becomes deeper in a direction intersecting the axis of the shaft 41. However, the escape groove 41b may have any shape as long as it can escape (avoid contact with) a corner on the upper inner diameter side of the washer 44. For example, it may have a shape that escapes to the upper side or diagonally upward on the inner diameter.

[0021] [Technical effect of the present embodiment] As described above, according to this embodiment, the shaft 41 and the tubular member 43 are in axial contact with each other via the washer 44, which has a higher hardness than the tubular member 43. This reduces friction between the cylindrical member 43 and the shaft 41 during hand movement, compared to when the cylindrical member 43 is in direct contact with the shaft 41. Therefore, the shaft 41 having the gear 42 can be supported in an appropriate manner. Furthermore, by reducing the friction of the shaft 41 during hand movement, the energy required for hand movement can be reduced and the generation of wear powder can be suppressed. In other words, the energy saving and life extension of the product is possible. In addition, since the backlash can be reduced, the position accuracy of the pointer 3 is improved. Here, the washer 45 is disposed between the train wheel bridge 22 and the gear 42 for the purpose of braking the second wheel 40A in order to improve the accuracy of the movement of the second hand 3s. As described above, by adopting the configuration of this embodiment, the positional accuracy of the pointer 3 is improved, so the washer 45, which has a common function, may be omitted. In that case, the effect of reducing the number of parts is obtained. It is also possible to replace the cylindrical member 43 itself with a harder material without using the washer 44. However, the cylindrical member 43 has a complex shape in order to avoid contact with the shaft 41 of the second wheel & pinion 40A and the center wheel & pinion body 51. Therefore, if the cylindrical member 43 is made of a hard material, it becomes difficult to process and also difficult to crimp to the center bridge 23. By using the washer 44, it is possible to obtain the above-mentioned effects relatively easily compared to replacing the cylindrical member 43 itself with a hard material.

[0022] Further, according to this embodiment, the washer 44 is housed (fitted) in the countersunk hole 43b formed in the upper end surface of the cylindrical member 43. This makes it possible to avoid an increase in the vertical length that would accompany the insertion of the washer 44, compared to when the cylindrical member 43 directly supports the shaft 41, and it is possible to maintain the same thickness of the watch 100. Furthermore, the countersunk hole 43b makes it possible to appropriately position the washer 44 in the vertical and radial directions.

[0023] Furthermore, according to this embodiment, the cylindrical member 43 is provided with the relief groove 43c at the outer diameter side corner of the bottom surface of the countersunk hole 43b. This allows the washer 44 to be suitably held within the countersunk hole 43b. That is, the silicon washer 44 is very hard and is manufactured by photolithography, so that the corners are easily chipped when stress is concentrated, and it is difficult to chamfer the corners. Therefore, it is undesirable that the corners of the bottom surface of the countersunk hole 43b have a corner R that may interfere (contact) with the washer 44 during assembly. However, it is unavoidable that the corner R is formed at the corner in a normal cutting process. Therefore, the corner of the countersunk hole 43b of the cylindrical member 43 is subjected to additional cutting to remove the corner R and provide a relief groove 43c. This makes it possible to avoid interference between the washer 44 and the countersunk hole 43b during assembly. This makes it possible to suitably hold the washer 44 in the countersunk hole 43b without making the positioning of the washer 44 difficult by making the washer 44 smaller to avoid the corner R. The direction of the clearance groove 43c is preferably the up-down direction (axial direction) that coincides with the machining direction of the countersunk hole 43b. To make the direction of the clearance groove 43c the radial direction, an undercut is required with respect to the machining direction of the countersunk hole 43b. On the other hand, by making the machining direction of the clearance groove 43c the axial direction, the clearance groove 43c can be formed relatively easily by cutting.

[0024] Furthermore, according to this embodiment, the washer 44 is joined to the cylindrical member 43 with an adhesive. That is, the relief groove 43c on the bottom surface of the countersunk hole 43b can be used as a groove for collecting the adhesive. This makes it possible to suitably hold the adhesive in the countersunk hole 43b and to prevent excess adhesive from spilling out of the countersunk hole 43b, thereby making it possible to prevent malfunctions caused by adhesive spilling out of the countersunk hole 43b.

[0025] Furthermore, according to this embodiment, the shaft 41 is provided with a clearance groove 41b at a corner on the inner diameter side of the surface that comes into contact with the washer . This makes it possible to prevent the corners of the washer 44 from being damaged due to contact with the shaft 41.

[0026] Furthermore, according to this embodiment, the washer 44 is made of silicon. In other words, by using the washer 44 made of silicon, which has high lubricity, the friction of the shaft 41 during hand movement can be further reduced.

[0027] [others] Incidentally, the embodiments to which the present invention can be applied are not limited to the above-described embodiments, and it goes without saying that various modifications are possible without departing from the gist of the present invention.

[0028] For example, in the above embodiment, the washer 44 supporting the shaft 41 is made of silicon. However, the material (substrate) of the washer 44 is not limited to silicon as long as it has a higher hardness than the cylindrical member 43. The material of the shaft 41 is not limited to carbon tool steel (SK material) and may be any metal having high hardness. The cylindrical member 43 may be made of any metal having a lower hardness than the shaft 41.

[0029] In the above embodiment, the cylindrical member 43 and the shaft 41 are provided with escape grooves to avoid contact with the washer 44. However, it is sufficient that an escape groove is provided in at least one of the cylindrical member 43 and the shaft 41 at a position facing the corner of the washer 44.

[0030] In the above embodiment, the fourth wheel has been described as an example of the gear assembly according to the present invention. However, the gear assembly according to the present invention can be applied to other parts of the train wheel mechanism besides the fourth wheel. For example, it may be used in a train wheel mechanism for a time hand other than a second hand, or in a train wheel mechanism for a function hand that displays various functions other than the time. Furthermore, the gear assembly according to the present invention is not limited to use in the wheel train mechanism of a timepiece, but can be widely applied to structures in which a shaft having a gear is supported by a cylindrical member (a member having a hole). In particular, it can be suitably applied to small gear mechanisms in which it is difficult to employ a complex bearing structure. [Explanation of symbols]

[0031] 100 Watches 101 Main body case (case) 3 Guidelines 3h hour hand 3m minute hand 3s second hand 21 Main plate 22 Wheel train support 23 Second Reception 30 Drive mechanism 30h hour hand movement mechanism 30m Minute hand drive mechanism 30s Second hand movement 32 Motor 32h 3rd motor 32m Second motor 32s 1st motor 33 Wheel train mechanism 33h 3rd wheel train mechanism 33m 2nd wheel train mechanism 33s 1st wheel train mechanism 40 Gear assembly 40A Fourth wheel 41 Shaft 41a Large diameter section 41b Relief groove 42 Gear 43 Cylindrical member 43a Fixed part 43b Counterbore 43c Undercut 44 Washer Ax center axis

Claims

1. a shaft having a gear; a cylindrical member into which the shaft is inserted; The shaft and the tubular member are in axial contact with each other via a washer having a harder hardness than the tubular member. Gear assembly.

2. At least one of the cylindrical member and the shaft is provided with a relief groove at a position facing a corner of the washer. The gear assembly according to claim 1 .

3. The cylindrical member has a countersunk hole on an axial end surface, The washer is received in the countersunk hole. The gear assembly according to claim 2.

4. The cylindrical member is provided with the relief groove at a corner portion on an outer diameter side of a bottom surface of the countersunk hole. The gear assembly according to claim 3.

5. The relief groove of the tubular member is provided so as to become deeper in the axial direction of the shaft. The gear assembly according to claim 4.

6. the washer is made of silicon; The washer is fixed in the countersunk hole by crimping an end portion of the cylindrical member on the side having the countersunk hole with the washer accommodated in the countersunk hole. The gear assembly according to claim 3.

7. The washer is bonded to the tubular member with an adhesive. The gear assembly according to claim 4.

8. The shaft has the relief groove at a corner portion on the inner diameter side of a surface that contacts the washer. The gear assembly according to claim 2.

9. The relief groove of the shaft is provided so as to become deeper in a direction intersecting the axis of the shaft. The gear assembly according to claim 8.

10. The washer is made of silicone. The gear assembly according to any one of claims 1 to 5 and 7 to 9.

11. The shaft is made of a high-hardness metal. The cylindrical member is made of a metal having a hardness lower than that of the shaft. The gear assembly according to claim 10.

12. A gear train mechanism including the gear assembly according to any one of claims 1 to 9; a case that houses the gear train mechanism; A watch equipped with.

13. A gear train mechanism including the gear assembly according to claim 10; a case that houses the gear train mechanism; A watch equipped with.

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