Gear set, movement and timepiece

Abstract

Provided are a gear set, a movement, and a timepiece that can compensate for backlash and thus stably transmit motion between a first gear and a second gear. A gear set includes a first gear and a second gear. Each tooth of the first gear includes a rigid tooth having a first active tooth surface that transmits motion to or from the second gear, and an elastic tooth that is disposed separately from the rigid tooth with a gap therebetween and that is capable of flexing in a direction closer to the rigid tooth when engaged with the second gear. The elastic tooth has a first non-active tooth surface that abuts the second gear. The thickness of each tooth of the first gear is greater than the width of a tooth space on a pitch circle of the second gear. The thickness of each tooth of the first gear is the sum of the thickness of the rigid tooth on the pitch circle of the first gear in a free state in which the tooth is not engaged with the second gear, the width of the gap, and the thickness of the elastic tooth. The width of the tooth space on the pitch circle of the first gear is less than the thickness of each tooth on the pitch circle of the second gear.

Description

Technical Field

[0001] This invention relates to gear sets, watch movements, and timepieces. Background Technology

[0002] To reduce backlash, gears with teeth capable of elastic deformation are known. For example, Patent Document 1 discloses a gear having backlash correction teeth with two elastically curved portions.

[0003] Patent Document 1: Japanese Patent Publication No. 2007-518981

[0004] The gear with backlash correction teeth in Patent Document 1 transmits motion while elastically deforming due to the contact between each elastically bent part and the teeth of other gears, making it difficult to stably transmit motion to the other gear. Summary of the Invention

[0005] The gear set disclosed herein is characterized in that the gear set includes a first gear and a second gear, each tooth of the first gear being configured to include: a rigid tooth having a first active tooth surface that transmits motion to or is transmitted by the second gear; and an elastic tooth that is separated from the rigid tooth by a gap and is capable of flexing toward the rigid tooth when meshing with the second gear, the elastic tooth having a first non-active tooth surface that abuts against the second gear, the tooth thickness of each tooth of the first gear being greater than or equal to the width of the tooth groove on the pitch circle of the second gear, wherein the tooth thickness of each tooth of the first gear is the sum of the thickness of the rigid tooth on the pitch circle of the first gear in a free state not meshing with the second gear, the width of the gap, and the thickness of the elastic tooth, and the width of the tooth groove on the pitch circle of the first gear being less than or equal to the tooth thickness of each tooth on the pitch circle of the second gear.

[0006] The movement disclosed herein is characterized by including the gear set.

[0007] The watch disclosed herein is characterized by including the aforementioned movement. Attached Figure Description

[0008] Figure 1 This is a top view showing a mechanical clock.

[0009] Figure 2 This is a top view of the movement of a mechanical watch, viewed from the front side.

[0010] Figure 3 This is a top view showing the structure of the third gear, which serves as the first gear.

[0011] Figure 4 This is an enlarged top view showing the teeth of the third gear, which is the first gear.

[0012] Figure 5 This is an enlarged view showing the meshing state of the third gear, which is the first gear, and the second gear, which is the second gear.

[0013] Figure 6 This is an enlarged view showing the meshing state of the third gear, which is the first gear, and the second gear, which is the second gear.

[0014] Figure 7 This is an enlarged view showing the meshing state of the third gear, which is the first gear, and the second gear, which is the second gear.

[0015] Figure 8 This is an enlarged view showing the meshing state of the third gear, which is the first gear, and the second gear, which is the second gear.

[0016] Label Explanation

[0017] 1: Mechanical clock; 10: Movement; 50: Gear; 51, 51A, 51B, 51C: Gear; 52: Rim; 55: Tooth groove; 59: Pitch circle; 60, 60A, 60B, 60C: Rigid tooth; 61: First working tooth surface; 70, 70A, 70B, 70C: Flexible tooth; 71: First non-working tooth surface; 75: Gap; 290, 290A, 290B: Tooth; 291: Second working tooth surface; 292: Second non-working tooth surface; 295: Tooth groove; 299: Pitch circle; 611: Working tooth root surface; 612: Working curved surface; 711: Non-working tooth root surface; 712: Non-working curved surface. Detailed Implementation

[0018] Hereinafter, the gear set, movement, and clock of this embodiment will be described with reference to the accompanying drawings.

[0019] In the following figures, to make each layer and component appear identifiable, they are sometimes represented at a different scale than they actually are.

[0020] Figure 1 This is a top view showing mechanical clock 1. Figure 2 This is a top view showing the movement 10 of the mechanical clock 1. Furthermore, in this embodiment, in the mechanical clock 1, the side with the glass cover is designated as the reverse side, and the side with the back cover is designated as the front side. Therefore, Figure 1 This is a top view of the mechanical clock 1 as seen from the side of the glass case. Figure 1 The front side of the paper is the reverse side, and the inside side is the front side. Additionally, Figure 2 This is a top view of the movement 10 viewed from the back cover side. Figure 2 The front side of the paper is the front side, and the inside side of the paper is the back side.

[0021] like Figure 1As shown, the mechanical watch 1 has a case 2 and a strap 9. The case 2 houses the dial 3, hour hand 4, minute hand 5, small seconds hand 6, date wheel 7, and... Figure 2 The movement 10 is shown. Additionally, a crown 8 is provided on the side of the case 2. This mechanical clock 1 is an example of a clock.

[0022] like Figure 2 As shown, the movement 10 has a base plate 11. The base plate 11 is a plate component used to support or position the various parts. The dial 3 is arranged on the reverse side of the base plate 11. Gear trains consisting of multiple gears are arranged on the front and back sides of the base plate 11. The gear train arranged on the front side of the base plate 11, i.e., the back cover side, is also called the front gear train, and the gear train arranged on the back side of the base plate 11, i.e., the dial 3 side, is also called the back gear train.

[0023] A handle guide hole 11A is formed in the base plate 11, parallel to the base plate 11 and guiding the shaft-shaped handle 12 in a direction from the outer edge toward the center. Furthermore, the handle 12 is assembled to be able to move axially and rotate about the axis relative to the handle guide hole 11A. A handle head 8 is mounted at the end of the handle 12. A pull stop 13, a clutch lever 14, a clutch lever spring 15, and a pull stop compression spring 16 are arranged near the handle 12. The pull stop 13, clutch lever 14, clutch lever spring 15, and pull stop compression spring 16 constitute a switching mechanism for switching the destination of the rotational force transmission of the handle 12.

[0024] The stem 12 is inserted through a rotatable vertical wheel 17 that is coaxial with and can rotate. Additionally, a clutch wheel (not shown) that rotates together with the stem 12 is disposed on the stem 12. The clutch wheel rotates coaxially with the stem 12 and can move axially along the stem 12 via a switching mechanism. When the stem 12 changes position axially, the switching mechanism switches between a state where the clutch wheel is engaged with the vertical wheel 17 and a state where it is not engaged. Furthermore, a small steel wheel 20 that engages with the vertical wheel 17, a large steel wheel 21 that engages with the small steel wheel 20, and a barrel wheel 22 for storing the mainspring are rotatably disposed on the base plate 11.

[0025] When the stem 12 is moved axially to the first stem position closest to the center of the movement 10, the clutch wheel engages with the upright wheel 17. In this state, when the operator rotates the stem 12 by operating the crown 8, the upright wheel 17 rotates together with the clutch wheel. Furthermore, the rotation of the upright wheel 17 causes the pinion wheel 20 to rotate. Moreover, the rotation of the pinion wheel 20 causes the mainspring wheel 21 to rotate. Furthermore, the rotation of the mainspring wheel 21 winds the mainspring stored in the barrel wheel 22. The mainspring is the power source driving the movement 10. In addition, when the stem 12 is positioned further outward than the first stem position, the engagement between the clutch wheel and the upright wheel 17 is disengaged, and the clutch wheel engages with a setting wheel (not shown) used for timekeeping, etc.

[0026] Wheel 25, wheel 26, and wheel 27 are rotatably arranged on the base plate 11. Wheel 25, wheel 26, and wheel 27 each have an integrally rotating gear and a twirling wheel. The aforementioned front gear train consists of the barrel wheel 22, wheel 25, wheel 26, and wheel 27. The front gear train functions to transmit the rotational force of the barrel wheel 22. Furthermore, on the front side of the movement 10, an escapement mechanism 30 and a regulating mechanism 31 are arranged on the base plate 11. The escapement mechanism 30 and the regulating mechanism 31 adjust the rotational speed of the front gear train.

[0027] A not shown wheel sprocket of wheel 25 engages with barrel wheel 22. A not shown minute wheel is mounted on wheel 25, and a minute hand 5 is mounted on the minute wheel. Additionally, the minute wheel engages with a cross wheel of a reverse gear train (not shown), and the cross wheel engages with an hour wheel of the reverse gear train (not shown). An hour hand 4 is mounted on the hour wheel.

[0028] The gear of wheel 25 meshes with the truncation 81 of wheel 36. Wheel 36 meshes with the truncation 28 of wheel 47 and the second wheel 29 used by the small seconds hand 6.

[0029] The escapement mechanism 30 is a mechanism for controlling the rotation of the front gear train. The escapement mechanism 30 includes an escape wheel 35 and an escape fork 36. The escape wheel 35 has a pinion that meshes with a gear on the fourth wheel 27 and rotates under the torque of the fourth wheel 27. The escape fork 36 rotates the escape wheel 35 regularly in conjunction with the action of the regulating mechanism 31. The regulating mechanism 31 includes a balance wheel and hairspring mechanism 40 and a hairspring 41, etc., and adjusts the rotational speed of the escape wheel 35 by causing the balance wheel and hairspring mechanism 40 to oscillate at a constant period, thereby adjusting the rotational speed of the front gear train meshing with the escape wheel 35.

[0030] Next, the third wheel 26 among the various components mentioned above will be described in detail.

[0031] Figure 3 This is a top view showing the structure of wheel 26, number three.

[0032] like Figure 3 As shown, wheel 26 includes a gear 50 and a shaft portion 80 serving as the rotation axis of the gear 50. The gear 50 consists of an annular rim portion 52 with multiple teeth 51 on its outer circumferential surface, a retaining portion 53 through which the shaft portion 80 is inserted, and multiple connecting portions 54 extending radially from the retaining portion 53 and connecting the rim portion 52 to the retaining portion 53. An opening 50A is formed in the gear 50, surrounded by the rim portion 52, the retaining portion 53, and two adjacent connecting portions 54. Gear 50 meshes with the twisting wheel 28 and the second wheel 29 of wheel 27.

[0033] In this embodiment, gear 50 of wheel 26 is the first gear, and the truncate wheel 28 and the second wheel 29 meshing with gear 50 are the second gears. Furthermore, a gear set is formed by gear 50 as the first gear, truncate wheel 28 as the second gear, and second wheel 29.

[0034] A sprocket 81, which meshes with the gear of the second gear 25, is integrally formed on the shaft portion 80. The shaft portion 80 is inserted through a hole (not shown) formed in the center of the gear 50 and is fixed to the gear 50. Therefore, the gear 50 and the sprocket 81 rotate integrally.

[0035] The gear 50 is plate-shaped and has a generally uniform thickness covering its entire surface. The gear 50 is made of a brittle material with a crystalline orientation, such as monocrystalline silicon. In this embodiment, the gear 50 is made of monocrystalline silicon. Specifically, the gear 50 is formed by etching a silicon wafer made of monocrystalline silicon. The manufacturing method of the gear 50 will be described later.

[0036] like Figure 3 and Figure 4 As shown, the gear 50 is provided with a plurality of teeth 51 consisting of rigid teeth 60 and elastic teeth 70.

[0037] Rigid teeth 60 are formed radially from the rim portion 52 and are formed at constant intervals along the outer periphery of the rim portion 52. Flexible teeth 70 are formed radially from the rim portion 52 and are formed at constant intervals along the outer periphery of the rim portion 52. In addition, rigid teeth 60 and flexible teeth 70 are formed alternately along the outer periphery of the rim portion 52.

[0038] Each tooth 51 is composed of rigid teeth 60 with their ends bent toward each other and elastic teeth 70.

[0039] Rigid tooth 60 is the driving tooth that transmits motion to the pawl 28 and sprocket 29 of wheel 4 27, such as... Figure 4 As shown, the rigid tooth 60 has a first working tooth surface 61 and an inner surface 62.

[0040] The first working tooth surface 61 is the surface that abuts against the gear 28 and the second gear 29 to transmit motion, and has a working tooth root surface 611 and a working curved surface 612. The working tooth root surface 611 is a surface that extends radially in a generally straight line from the rim portion 52. The working curved surface 612 is a surface that extends from the working tooth root surface 611 toward the tooth tip and curves toward the elastic tooth 70, and is the surface that abuts against the teeth of the gear 28 and the second gear 29 to transmit motion.

[0041] The inner surface 62 is the surface opposite to the elastic tooth 70, and it is the surface that divides the space between the inner surface 62 and the elastic tooth 70 to form a gap 75. The inner surface 62 has a base end face 621 and a tip face 622. The base end face 621 extends from the rim portion 52 in a generally straight line and is disposed generally parallel to the root face 611 of the working tooth. The width dimension W1 between the root face 611 of the working tooth and the base end face 621 is a generally constant width dimension, for example, about 100 μm. The width dimension W1 of the rigid tooth 60 is set such that when the rigid tooth 60 meshes with other gears such as the truncate gear 28 and the sprocket 29, the rigid tooth 60 becomes a rigid tooth that can transmit motion without elastic deformation.

[0042] The end face 622 is a curved surface that extends from the base end face 621 toward the tooth tip and curves toward the action bending surface 612. Therefore, the width dimension between the action bending surface 612 and the end face 622 is formed to decrease as it moves toward the tooth tip of the rigid tooth 60.

[0043] The elastic tooth 70 is a tooth that elastically deforms and flexes without being used for motion transmission, thereby abutting against the teeth of the gear 28 and the second wheel 29 to compensate for backlash. It has a first non-active tooth surface 71 and an inner surface 72. The first non-active tooth surface 71 is the surface that abuts against the gear 28 and the second wheel 29 to compensate for backlash, and it has a non-active tooth root surface 711 and a non-active curved surface 712. The non-active tooth root surface 711 is a surface that extends radially in a generally straight line from the rim portion 52. The non-active curved surface 712 is a surface that extends from the non-active tooth root surface 711 towards the tooth tip and curves towards the rigid tooth 60, and is the surface that abuts against the teeth of the gear 28 and the second wheel 29.

[0044] The inner surface 72 is the surface opposite to the rigid tooth 60, and it is the surface that divides the space between the inner surface 72 and the rigid tooth 60 to form a slit 75. The inner surface 72 has a base end face 721 and a tip face 722. The base end face 721 extends from the rim portion 52 in a generally straight line and is disposed approximately parallel to the non-active tooth root face 711. The width dimension W2 between the non-active tooth root face 711 and the base end face 721 is a generally constant width dimension, for example, about 30 μm. The tip face 722 is a curved surface that extends from the base end face 721 toward the tooth tip and is curved in the same way as the non-active curved surface 712. The width dimension W2 of the elastic tooth 70 is smaller than the width dimension W1 of the rigid tooth 60, and the elastic tooth 70 is set to a size that allows it to elastically deform as a whole.

[0045] As explained above, tooth 51 has rigid teeth 60 and flexible teeth 70, with a gap 75 formed between the rigid teeth 60 and the flexible teeth 70. The gap 75 is formed by the inner surface 62 of the rigid teeth 60, the rim portion 52, and the inner surface 72 of the flexible teeth 70. The width dimension W3 of tooth 51 is a value obtained by adding the width dimension W1 of the rigid teeth 60, the width dimension W2 of the flexible teeth 70, and the width dimension of the gap 75. In the free state when not engaged with the gear 28 and the gear 29, the width dimension W3 is, for example, approximately 220 μm.

[0046] The length L1 from the root (rim portion 52) of the rigid tooth 60 to the tip and the length L2 from the root to the tip of the elastic tooth 70 are set such that L2 > L1. For example, L2 is approximately 900 μm and L1 is approximately 890 μm. Furthermore, the length from the shaft portion 80 (which is the rotation center of the gear 50) to the outer periphery of the rim portion 52, in other words, from the shaft portion 80 to the rigid tooth 60 and the elastic tooth 70, is the same.

[0047] Furthermore, the gear 50 is formed, for example, by anisotropic etching of a photoresist pattern formed on the surface of a silicon-containing wafer-like substrate and deep etching in the thickness direction of the substrate. That is, the gear 50 is manufactured using MEMS (Micro Electro Mechanical Systems) technology. Therefore, the gear 50, including its tooth 51 (with rigid teeth 60 and elastic teeth 70), rim portion 52, holding portion 53, and connecting portion 54, can be formed from the same substrate using the same etching process. Multiple gears 50 can be obtained from a single substrate, thus improving the productivity of the gear 50 and reducing production costs. In addition, since it is formed using photolithography or etching technology, it also has the advantages of high shape freedom and improved machining accuracy of the gear 50.

[0048] In this embodiment, the thickness of the silicon wafer is approximately 100 μm to 200 μm. The thickness of the silicon wafer corresponds to the tooth width of the gear 50. Furthermore, the diameter of the tooth tip circle (not shown), i.e., the circle passing through the end of the tooth 51, is approximately 5 mm to 7 mm. Moreover, as... Figure 4As shown, the tooth thickness SA of tooth 51 is the length of the arc on the pitch circle 59 in the free state, and is the sum of the length of the arc (thickness S1) of the rigid tooth 60 on the pitch circle 59, the length of the arc (thickness S2) of the elastic tooth 70 on the pitch circle 59, and the width S3 of the gap 75 on the pitch circle 59. That is, SA = S1 + S2 + S3. The pitch circle 59 is the circle connecting the meshing nodes of gear 50 (the first gear) and gears 28 and 29 (the second gears). Therefore, the tooth thickness SA of tooth 51 varies slightly depending on the distance between the shafts of gear 50 and gears 28 and 29, and the tooth profile, but in this embodiment, the tooth thickness SA is approximately 190 to 240 μm. In addition, the length of the arc (width S5) of the tooth groove 55 between adjacent teeth 51 on the pitch circle 59 is set as S5. The width S5 of the tooth groove 55 is approximately 60 to 80 μm. The tooth groove 55 of each tooth 51 is formed between the first active tooth surface 61 of the rigid tooth 60 of one tooth 51 and the first non-active tooth surface 71 of the elastic tooth 70 of the other tooth 51. In addition, the tooth width, the diameter of the tooth tip circle, the tooth thickness, and the width of the tooth groove are not limited to the above ranges, and may be outside the above ranges.

[0049] The tooth thickness SA of gear 50's tooth 51 is set to be greater than the width dimension of the tooth grooves on the pitch circle of gears 28 and 29. Gears 28 and 29, serving as the second gears, are gears of the same size and shape; for example, when set... Figure 5 When the length of the arc of each tooth 290 on the pitch circle 299 of the second wheel 29 shown is S21, and the length of the arc of the tooth groove 295 between each tooth 290 on the pitch circle 299 is S22, S21 is approximately 70-90 μm and S22 is approximately 170-190 μm.

[0050] Here, the tooth thickness SA of tooth 51 is greater than or equal to the width S22 of the tooth groove 295 between teeth 290. That is, SA ≥ S22. Therefore, when tooth 51 of gear 50, which is the first gear, is positioned in the tooth groove 295 of gear 28 and gear 29, which are the second gears, the active bending surface 612 of rigid tooth 60 abuts against the second active tooth surface 291 of tooth 290, and the non-active bending surface 712 of elastic tooth 70 abuts against the second non-active tooth surface 292 of tooth 290. In this case, the tooth thickness SA of tooth 51 is greater than the width S22 of the tooth groove 295 between teeth 290. When SA > S22, when tooth 51 of gear 50, which is the first gear, is positioned in the tooth groove 295 of gear 28 and gear 29, which are the second gears, elastic tooth 70 elastically deforms in a direction close to rigid tooth 60, and the non-active bending surface 712 of elastic tooth 70 abuts against the second non-active tooth surface 292 of tooth 290. Furthermore, when the tooth thickness SA of tooth 51 is the same as the width S22 of the tooth groove 295 between tooth 290, and SA=S22, when the tooth 51 of gear 50, which is the first gear, is arranged in the tooth groove 295 of the gear 28 and gear 29, which are the second gears, even if the elastic tooth 70 does not elastically deform, the non-active bending surface 712 of the elastic tooth 70 abuts against the second non-active tooth surface 292 of tooth 290. Thus, the rigid tooth 60 and the elastic tooth 70 abut against tooth 290 respectively, thereby compensating for backlash.

[0051] Further, the width S5 of the tooth grooves 55 between the respective teeth 51 of the gear 50 is less than or equal to the tooth thickness S21 of the respective teeth 290 of the second wheel 29. That is, S5 ≤ S21. Therefore, even in a state where the respective teeth 290 of the second wheel, which serves as the second gear, are disposed in the tooth grooves 55 between the respective teeth 51 of the gear 50, which serves as the first gear, the acting curved surface 612 of the rigid tooth 60 also abuts against the second acting tooth surface 291 of the tooth 290, and the non-acting curved surface 712 of the elastic tooth 70 abuts against the second non-acting tooth surface 292 of the tooth 290. In this case, when the width S5 of the tooth grooves 55 between the respective teeth 51 of the gear 50 is smaller than the tooth thickness S21 of the respective teeth 290 of the second wheel 29, that is, S5 < S21, in the state where the respective teeth 290 of the second wheel serving as the second gear are disposed in the tooth grooves 55 between the respective teeth 51 of the gear 50 serving as the first gear, the elastic tooth 70 elastically deforms in a direction approaching the rigid tooth 60, and the non-acting curved surface 712 of the elastic tooth 70 abuts against the second non-acting tooth surface 292 of the tooth 290. In addition, when the width S5 of the tooth grooves 55 between the respective teeth 51 of the gear 50 is equal to the tooth thickness S21 of the respective teeth 290 of the second wheel 29, that is, S5 = S21, in the state where the respective teeth 290 of the second wheel serving as the second gear are disposed in the tooth grooves 55 between the respective teeth 51 of the gear 50 serving as the first gear, even if the elastic tooth 70 does not undergo elastic deformation, the non-acting curved surface 712 of the elastic tooth 70 also abuts against the second non-acting tooth surface 292 of the tooth 290. Accordingly, the rigid tooth 60 and the elastic tooth 70 respectively abut against the tooth 290, so that the backlash can be compensated.

[0052] The tooth thickness SA of tooth 51 and the width S22 of tooth groove 295 are set considering manufacturing errors. For example, in this embodiment, gear 50, which is the first gear, is manufactured using MEMS technology as described above, so its first tolerance is about ±5 μm. The second gear, the second gear 29, is manufactured using MEMS technology or machining. The second tolerance is about ±5 μm when manufactured using MEMS technology, and about ±20 μm when manufactured using machining. Furthermore, the difference Δt between the tooth thickness SA of tooth 51 and the width S22 of tooth groove 295, i.e., the overlap Δt between tooth 51 and tooth 290 in the design, is a value greater than or equal to the sum of the first tolerance of gear 50 and the second tolerance of second gear 29. For example, when both gear 50 and second gear 29 are manufactured using MEMS technology, the sum of each tolerance is about 10 μm, and when gear 50 is manufactured using MEMS technology and second gear 29 is manufactured using machining, the sum of each tolerance is about 25 μm. Furthermore, gear 50 and second wheel 29 are designed such that the difference Δt = SA - S22 between the tooth thickness SA of tooth 51 and the width S22 of tooth groove 295 is greater than or equal to the sum of the aforementioned tolerances. Therefore, even if there are manufacturing errors in the tooth profiles of gear 50 and second wheel 29, when tooth 51 of gear 50 meshes with tooth groove 295 of second wheel 29, rigid tooth 60 and elastic tooth 70 can reliably abut against tooth 290, and backlash can be reliably reduced.

[0053] The tooth thickness SA of tooth 51 and the width S22 of tooth groove 295 are dimensions on pitch circles 59 and 299, respectively. Therefore, the overlap Δt also varies depending on the distance between the shafts of gear 50 and the second wheel 29. Thus, manufacturing errors in the distance between the shafts can be considered, and the design can further increase the overlap Δt. Considering the sum of the above tolerances and the error in the distance between the shafts, when both gear 50 and the second wheel 29 are manufactured using MEMS technology, the overlap Δt ranges from approximately 10 to 100 μm. When gear 50 and the second wheel 29 are manufactured using MEMS technology and machining, the overlap Δt ranges from approximately 25 to 100 μm. For example, when the distance between the shafts of gear 50 and the second wheel 29 varies by ±20 μm, i.e., a maximum of 40 μm, the overlap Δt will, for example, vary by approximately 30 μm. Therefore, if the difference between the tooth thickness SA of tooth 51 and the width S22 of tooth groove 295 is set to a maximum of about 100μm, the rigid tooth 60 and the elastic tooth 70 can reliably abut against tooth 290, and the tooth gap can also be reliably reduced.

[0054] In addition, the width S5 of the tooth groove 55 of tooth 51 and the tooth thickness S21 of tooth 290 can be designed in the same way as the tooth thickness SA of tooth 51 and the width S22 of tooth groove 295, taking into account the manufacturing errors of various tolerances and inter-axis distances.

[0055] Reference Figures 5 to 7The meshing state of gear 50, which serves as the first gear, and the second gear, the second gear, 29, will be explained. In this embodiment, gear 50, which serves as the third gear 26, transmits motion to the truncate gear 28 and the second gear 29. Therefore, in Figures 5 to 7 In the process, when gear 50 rotates in the first clockwise direction D1, the rigid teeth 60 of each tooth 51 successively abut against the teeth 290 of the second wheel 29, and the second wheel 29 rotates in the second counterclockwise direction D2. At this time, among the teeth 290 of the second wheel 29, the surface that abuts against the first active tooth surface 61 of the rigid tooth 60 is the second active tooth surface 291, and the surface that abuts against the first non-active tooth surface 71 of the elastic tooth 70 is the second non-active tooth surface 292.

[0056] Figure 5 This shows the state in which the teeth 290 of the second wheel 29 are configured in the tooth grooves 55 of the gear 50. Furthermore, in Figures 5 to 7 For ease of explanation, the continuous portion of teeth 51, rigid teeth 60, and elastic teeth 70 are designated as teeth 51A, 51B, 51C, rigid teeth 60A, 60B, 60C, and elastic teeth 70A, 70B, 70C. Additionally, the continuous portion of teeth 290 that meshes with teeth 51A, 51B, and 51C is designated as teeth 290A and 290B.

[0057] exist Figure 5 In this configuration, the first working tooth surface 61 of the rigid tooth 60B of tooth 51B abuts against the second working tooth surface 291 of tooth 290A to transmit motion. Furthermore, the elastic tooth 70A, positioned on the first direction D1 side with a tooth groove 55 between itself and the rigid tooth 60B abutting against tooth 290A, abuts against the second non-working tooth surface 292 of tooth 290A, thereby reducing tooth backlash. At this time, the elastic tooth 70A elastically deforms towards the first direction D1 side, i.e., towards the rigid tooth 60A side. Additionally, a gap 75 is formed between the rigid tooth 60A and the elastic tooth 70A, configured such that even when the elastic tooth 70A elastically deforms towards the rigid tooth 60A side, the end of the elastic tooth 70A does not contact the end of the rigid tooth 60A. Additionally, the elastic tooth 70B, which together with the rigid tooth 60B that abuts against tooth 290A forms tooth 51B, is located on the rear side of rigid tooth 60B relative to the first direction D1, which is the rotation direction of gear 50, at a position slightly away from the second non-operating tooth surface 292 of the next tooth 290B after tooth 290A.

[0058] Figure 6 It is gear 50 from Figure 5 The state begins with a slight rotation towards the first direction, D1. Figure 6During this process, as gear 50 rotates in the first direction D1, tooth 290A of the second wheel 29, located in the tooth groove 55 between the rigid tooth 60B and the elastic tooth 70A, is pushed by the rigid tooth 60B and moves in the second direction D2. At this time, the elastic tooth 70A remains in contact with tooth 290A, and the tooth backlash decreases.

[0059] In addition, the elastic tooth 70B is positioned just before it comes into contact with the second non-active tooth surface 292 of the tooth 290B.

[0060] Figure 7 It is gear 50 from Figure 6 The state begins with a slight rotation towards the first direction, D1. Figure 7 In the process, since gear 50 rotates in the first direction D1, the tooth 290A of the second wheel 29, which is located in the tooth groove 55 between the rigid tooth 60B and the elastic tooth 70A, is pushed by the rigid tooth 60B and moves in the second direction D2. The elastic tooth 70B abuts against the second non-acting tooth surface 292 of the tooth 290B. Therefore, the rigid tooth 60B and the elastic tooth 70B of gear 51B are located in the tooth groove 295 between the teeth 290A and 290B. At this time, since the tooth thickness SA of gear 51B is larger than the width S22 of the tooth groove 295 between the teeth 290A and 290B, the elastic tooth 70B elastically deforms in the direction closer to the rigid tooth 60B, so that the rigid tooth 60B abuts against the tooth 290A and the elastic tooth 70B abuts against the tooth 290B, and the tooth backlash decreases.

[0061] In addition, Figure 7 In the process, the elastic tooth 70A separates from the tooth 290A by rotating the gear 50 in the first direction D1. In addition, the rigid tooth 60C of the next tooth 51C after tooth 51B is in the state just before it comes into contact with the second working tooth surface 291 of tooth 290B.

[0062] Furthermore, when gear 50 rotates in the first direction D1, the rigid tooth 60C of tooth 51C abuts against tooth 290B, causing the second wheel 29 to rotate in the second direction D2, becoming... Figure 5 The same state. Therefore, by rotating gear 50 in the first direction D1, the process repeats from... Figures 5 to 7 The state of the second wheel 29 causes it to rotate in the second direction D2. Furthermore, since at least one rigid tooth 60 is always in contact with the second active tooth surface 291 of the tooth 290, and at least one elastic tooth 70 is always in contact with the second non-active tooth surface 292 of the tooth 290, the second wheel 29 can be rotated while reducing backlash, thereby allowing the small second hand 6 mounted on the second wheel 29 to move smoothly without deviation.

[0063] The rigid tooth 60 and elastic tooth 70 constituting tooth 51 are formed as an active curved surface 612 and a non-active curved surface 712, respectively, with the tooth tips of the first active tooth surface 61 and the first non-active tooth surface 71 laterally bent towards each other. Therefore, the tooth thickness of tooth 51 gradually decreases towards the tooth tip, while the width of tooth groove 55 gradually increases towards the tooth tip. Thus, tooth 51 can smoothly enter the tooth groove 295 of the second wheel 29, and tooth 290 can smoothly enter the tooth groove 55 of the gear 50.

[0064] Furthermore, the length L2 from the rim portion 52 to the end of the elastic tooth 70 is longer than the length L1 from the rim portion 52 to the end of the rigid tooth 60. Therefore, when the elastic tooth 70 begins to abut against the tooth 290, the non-active curved surface 712 of the elastic tooth 70 abuts against the tooth 290, thus allowing the elastic tooth 70 to flex smoothly. For example, when the end face of the elastic tooth 70 abuts against the tooth 290, the elastic tooth 70 and the tooth 290 press against each other, hindering the rotation of the gear 50 and the second wheel 29. In contrast, in this embodiment, the length L2 of the elastic tooth 70 is longer, and the end of the elastic tooth 70 bends towards the rigid tooth 60. Therefore, the end of the elastic tooth 70 does not abut against the tooth 290, and the continuous non-active curved surface 712 from the end abuts against the second non-active tooth surface 292 of the tooth 290. The elastic tooth 70 flexes smoothly, thus allowing the gear 50 and the second wheel 29 to rotate smoothly.

[0065] Figure 8 The diagram illustrates the force applied from tooth 290 to elastic tooth 70 when elastic tooth 70 begins to abut against tooth 290. Figure 8 As shown, the elastic tooth 70 begins to be subjected to force from the second wheel 29 at the tangent point P where it is tangent to tooth 290. At the moment when this force begins to be applied, a force Fn is applied from the second wheel 29 perpendicular to the tangent L of the tooth surface of the elastic tooth 70 at the tangent point P. The force Fn can be decomposed into a tangential force Ft and a radial force Fr. The tangential direction, which is the vector direction of the force Ft, is the direction of the tangent at the tangent point P of the circle centered on the rotation axis of gear 50 and passing through the tangent point P. The radial direction, which is the vector direction of the force Fr, is the radial direction of gear 50.

[0066] In Figure 8In the current state, the shape of the first non-active tooth surface 71 of the elastic tooth 70 is set such that the magnitude of force Ft > the magnitude of force Fr; specifically, the shape of the non-active curved surface 712 that abuts against tooth 290. That is, the inclination angle θ of the tangent L at the tangency point P is set to be less than 45°. Furthermore, the inclination angle θ is the angle between the tangent L and the radial direction of gear 50. In contrast, when the elastic tooth 70 is set such that its end abuts against tooth 290, the magnitude of force Ft ≤ the magnitude of force Fr, and the inclination angle θ becomes 45° or more. In this case, sometimes the elastic tooth 70 cannot bend smoothly inward, and the gear 29 hinders the rotation of gear 50.

[0067] According to this embodiment, the following effects are achieved.

[0068] Each tooth 51 of gear 50 has a rigid tooth 60 and an elastic tooth 70. The first working tooth surface 61 of the rigid tooth 60 abuts against the second working tooth surface 291 of the second wheel 29 to transmit motion between gear 50 and second wheel 29. Therefore, during motion transmission, the rigid tooth 60 does not undergo elastic deformation, so it can reliably and appropriately transmit motion between gear 50 and second wheel 29.

[0069] In addition, tooth 51 has elastic tooth 70, and the tooth thickness SA of tooth 51 is greater than or equal to the width S22 of the tooth groove 295 of the second wheel 29. Therefore, as Figure 7 As shown, when the rigid tooth 60 and the elastic tooth 70 of the tooth 51 are arranged in the tooth groove 295 of the second wheel 29, the first working tooth surface 61 of the rigid tooth 60 abuts against the second working tooth surface 291 of the tooth 290, and the first non-working tooth surface 71 abuts against the second non-working tooth surface 292 of the tooth 290. Therefore, the tooth backlash can be reduced and compensated.

[0070] Furthermore, the width S5 of the tooth groove 55 is smaller than the tooth thickness S21 of the tooth 290, therefore... Figure 5 As shown, when tooth 290 is sandwiched in tooth groove 55 between rigid tooth 60 and elastic tooth 70, elastic tooth 70 also abuts against tooth 290, which can reduce tooth gap and compensate.

[0071] Therefore, the gear set consisting of gear 50, second gear 29, and second gear 28 can reliably and appropriately transmit motion while reducing backlash.

[0072] The tooth thickness SA of gear 50's tooth 51 and the width S5 of tooth groove 55, as well as the tooth thickness S21 and the width S22 of tooth groove 290 of the second wheel 29, are set considering the tolerances of gear 50 and the second wheel 29. Therefore, even if there are manufacturing errors in the tooth profiles of gear 50 and the second wheel 29, the rigid tooth 60 and the flexible tooth 70 can reliably abut against tooth 290, reducing backlash. This reduces vibration of the small seconds hand 6 mounted on the second wheel 29 due to backlash, allowing the small seconds hand 6 to move smoothly. Furthermore, since the tooth thickness SA, S21 and the tooth groove widths S5, S22 are also set considering manufacturing errors in the distance between the shafts of gear 50 and the second wheel 29, even if there are manufacturing errors in the distance between the shafts of gear 50 and the second wheel 29, the rigid tooth 60 and the flexible tooth 70 can reliably abut against tooth 290, reducing backlash.

[0073] The portion of the first non-active tooth surface 71 of the elastic tooth 70 that abuts against the tooth 290 is designated as a non-active curved surface 712. The tooth profile of the elastic tooth 70 is set such that the inclination angle θ at the beginning of the contact between the non-active curved surface 712 and the second non-active tooth surface 292 is less than 45°. Therefore, the non-active curved surface 712 of the elastic tooth 70 can reliably contact the tooth 290, allowing the elastic tooth 70 to smoothly flex and deform. Thus, it is possible to prevent the end of the elastic tooth 70 from contacting the tooth 290 and hindering the rotation of the gear 50 and the second wheel 29.

[0074] A gap 75 is formed between the rigid tooth 60 and the elastic tooth 70. When the gear 50 and the second wheel 29 are engaged, the rigid tooth 60 and the elastic tooth 70 do not contact each other. Therefore, the elastic tooth 70 can be elastically deformed with a small force, which can improve the transmission efficiency of the gear set formed by the gear 50 and the second wheel 29.

[0075] Since the length dimension L2 of the elastic tooth 70 is longer than the length dimension L1 of the rigid tooth 60, the force required to elastically deform the elastic tooth 70 can be reduced compared to the case where the length dimension of the elastic tooth 70 is shorter than that of the rigid tooth 60. Therefore, the energy required to elastically deform the elastic tooth 70 can be reduced, thereby improving the transmission efficiency of the gear set.

[0076] The lengths from the rotation axis of gear 50 to the rigid tooth 60 and the flexible tooth 70 are the same, meaning the lengths from the rotation axis of gear 50 to the tooth roots of the tooth groove 55 and the slot 75 are the same. Therefore, the shapes of the rigid tooth 60 and the flexible tooth 70 are simple, making it easier to ensure the etching shape during plasma etching and improving manufacturing efficiency. Furthermore, the rigid tooth 60 and the flexible tooth 70 are simple shapes that extend from the rim portion 52 in the radial direction of gear 50 and only curve at their ends, thus making it easier to ensure the etching shape and improving manufacturing efficiency.

[0077] The above implementation method can also be modified as follows.

[0078] In the above embodiment, silicon, a plate-shaped component and a brittle material, is used as the material for gear 50, but the material of gear 50 is not limited to silicon. For example, it can also be silicon carbide, quartz, glass, sapphire, etc.

[0079] In the above embodiment, the gap 75 between the rigid tooth 60 and the elastic tooth 70 is configured such that it does not abut against the rigid tooth 60 when the elastic tooth 70 abuts against the tooth 290 and flexes due to elastic deformation. However, it can also be configured such that it abuts against the rigid tooth 60 when the elastic tooth 70 abuts against the tooth 290 and flexes due to elastic deformation. However, for the purpose of improving transmission efficiency, it is preferable to configure such that the entire length of the elastic tooth 70 from the root to the tip does not abut against the rigid tooth 60 when the elastic tooth 70 flexes. For example, if the elastic tooth 70 is in a shape that abuts against the rigid tooth midway from the root to the tip, then the area where elastic deformation can occur in the case of abutment becomes the area from the midway point to the tip of the elastic tooth 70. This is equivalent to the length of the elastic tooth 70 becoming shorter. When the length of the elastic tooth 70 becomes shorter, the flexibility decreases, and more energy is required to flex the elastic tooth 70. Therefore, compared to a shape where the entire length of the elastic tooth 70 from the root to the tip does not abut against the rigid tooth 60, the transmission efficiency decreases.

[0080] In the above embodiment, a gear 50 for the third gear 26 constituting the front gear train of a mechanical clock 1 is illustrated. However, the structure and manufacturing method of the gear 50 shown in the above embodiment can be applied to various gears, such as other gears constituting the front gear train and gears constituting the back gear train. Furthermore, the clock is not limited to the mechanical clock 1, but can also be other clocks such as electronic clocks. That is, the structure and manufacturing method of the gear 50 shown in the above embodiment can also be applied to gears included in electronic clocks and the like.

[0081] (Summary of this disclosure)

[0082] This disclosure relates to a gear set, characterized in that the gear set includes a first gear and a second gear, each tooth of the first gear being configured to include: a rigid tooth having a first active tooth surface that transmits motion to or is transmitted by the second gear; and an elastic tooth that is separated from the rigid tooth by a gap and is capable of flexing toward the rigid tooth when meshing with the second gear, the elastic tooth having a first non-active tooth surface that abuts against the second gear, the tooth thickness of each tooth of the first gear being greater than or equal to the width of the tooth groove on the pitch circle of the second gear, wherein the tooth thickness of each tooth of the first gear is the sum of the thickness of the rigid tooth on the pitch circle of the first gear in a free state when not meshing with the second gear, the width of the gap, and the thickness of the elastic tooth, and the width of the tooth groove on the pitch circle of the first gear being less than or equal to the tooth thickness of each tooth on the pitch circle of the second gear.

[0083] According to the gear set disclosed herein, each tooth of the first gear is configured to have rigid teeth and elastic teeth that are separated by a gap. The first working tooth surface of the rigid teeth abuts against the second working tooth surface of the second gear, thereby enabling motion to be transmitted between the first gear and the second gear. Therefore, motion can be transmitted reliably and appropriately between the first gear and the second gear.

[0084] The tooth thickness of each tooth of the first gear is the sum of the thickness of the rigid tooth on the pitch circle of the first gear in its free state, the width of the gap, and the thickness of the elastic tooth. This tooth thickness is greater than or equal to the width of the tooth groove on the pitch circle of the second gear. Therefore, when the rigid tooth and elastic tooth of one tooth of the first gear are positioned within the tooth groove of the second gear, the first working surface of the rigid tooth abuts against the second gear, and the elastic tooth abuts against the second gear through elastic deformation, thereby reducing backlash and compensating for the difference. Furthermore, since the width of the tooth groove on the pitch circle of the first gear is less than or equal to the tooth thickness on the pitch circle of the second gear, even when a tooth of the second gear is sandwiched between the elastic tooth of one tooth of the first gear and the rigid tooth of the next tooth, the elastic tooth will still abut against the second gear through elastic deformation, thereby reducing backlash and compensating for the difference.

[0085] In the gear set disclosed herein, preferably, the difference between the tooth thickness of each tooth of the first gear and the tooth groove width of the second gear is a value greater than or equal to the sum of the manufacturing error of the first gear (i.e., the first tolerance) and the manufacturing error of the second gear (i.e., the second tolerance).

[0086] According to this disclosure, since the difference between the tooth thickness of each tooth of the first gear and the tooth groove width of the second gear is greater than or equal to the sum of the manufacturing error of the first gear (i.e., the first tolerance) and the manufacturing error of the second gear (i.e., the second tolerance), even if there is a manufacturing error in the tooth profile of the first gear or the second gear, the rigid teeth and the elastic teeth can reliably abut against the second gear, thereby reducing the tooth backlash for compensation.

[0087] In the gear set disclosed herein, it is preferred that the gap of the first gear is configured such that, when meshing with the second gear, the rigid teeth and the elastic teeth do not contact each other.

[0088] According to this disclosure, when the teeth of the first gear mesh with the second gear, the rigid teeth and the elastic teeth do not come into contact with each other, so the elastic teeth can be elastically deformed with a small force, thereby improving the transmission efficiency of the first gear and the second gear.

[0089] In the gear set disclosed herein, preferably, the first active tooth surface of the rigid tooth is configured to include: an active tooth root surface extending radially from the rim of the first gear; and an active curved surface extending from the active tooth root surface toward the tooth tip and curving toward the elastic tooth side to abut against the second gear; the first non-active tooth surface of the elastic tooth includes: a non-active tooth root surface extending radially from the rim; and a non-active curved surface extending from the non-active tooth root surface toward the tooth tip and curving toward the rigid tooth side to abut against the second gear.

[0090] According to this disclosure, the active bending surface of the rigid tooth and the non-active bending surface of the elastic tooth can be made to abut against the teeth of the second gear, so that the elastic tooth can be reliably flexed, and the first gear and the second gear can be reliably rotated.

[0091] In the gear set disclosed herein, it is preferred that the first non-active tooth surface of the elastic tooth has the following shape: at the moment when the second gear begins to abut against the first non-active tooth surface, when the force Fn applied from the second gear in a direction perpendicular to the tangent at the tangent point on the first non-active tooth surface is decomposed into a force Ft in the tangential direction at the tangent point of the circle centered on the rotation axis of the first gear and passing through the tangent point, and a force Fr in the radial direction of the first gear, the magnitude of force Ft is greater than the magnitude of force Fr.

[0092] According to this disclosure, when the teeth of the first gear mesh with the second gear, the elastic teeth can be appropriately flexed towards the rigid teeth, and the first gear and the second gear can be appropriately rotated.

[0093] In the gear set disclosed herein, it is preferred that the first gear or the second gear is a gear equipped with a pointer.

[0094] According to this disclosure, since the backlash of the first or second gear is compensated, it is possible to reduce the vibration of the pointer mounted on these gears due to backlash.

[0095] The movement disclosed herein is characterized by including the gear set.

[0096] According to this disclosure, the movement is equipped with the gear set, thus enabling proper transmission of motion between the first gear and the second gear, and also reducing backlash.

[0097] The watch disclosed herein is characterized by including the aforementioned movement.

[0098] According to this disclosure, due to the presence of the aforementioned mechanism, motion can be appropriately transmitted between the first gear and the second gear, and backlash can also be reduced.

Claims

1. A gear set, characterized in that, The gear set includes a first gear and a second gear. The teeth of the first gear are configured to have: A rigid tooth, having a first working tooth surface that transmits motion to or is transmitted by the second gear; and The flexible tooth, which is separated from the rigid tooth by a gap, can flex towards the rigid tooth when meshing with the second gear. The flexible tooth has a first non-active tooth surface that abuts against the second gear. The tooth thickness of each tooth of the first gear is greater than or equal to the width of the tooth groove on the pitch circle of the second gear. The tooth thickness of each tooth of the first gear is the sum of the thickness of the rigid tooth on the pitch circle of the first gear in its free state when not meshing with the second gear, the width of the gap, and the thickness of the elastic tooth. The width of the tooth groove on the pitch circle of the first gear is less than or equal to the tooth thickness of each tooth on the pitch circle of the second gear.

2. The gear set according to claim 1, characterized in that, The difference between the tooth thickness of each tooth of the first gear and the tooth groove width of the second gear is greater than or equal to the sum of the manufacturing error of the first gear (i.e., the first tolerance) and the manufacturing error of the second gear (i.e., the second tolerance).

3. The gear set according to claim 1, characterized in that, The gap of the first gear is configured such that, when meshing with the second gear, the rigid teeth and the elastic teeth do not contact each other.

4. The gear set according to claim 1, characterized in that, The first working tooth surface of the rigid tooth is configured to have: The action surface of the tooth root extends radially from the rim of the first gear; and An action-bending surface extends from the action-tooth root surface toward the tooth tip and bends toward the elastic tooth side to abut against the second gear. The first non-active tooth surface of the elastic tooth has: A non-functional tooth root surface that extends radially from the rim portion; and A non-active curved surface extends from the non-active tooth root surface toward the tooth tip and bends toward the rigid tooth side to abut against the second gear.

5. The gear set according to claim 1, characterized in that, The first non-active tooth surface of the elastic tooth has the following shape: At the moment when the second gear begins to contact the first non-active tooth surface, the force Fn applied from the second gear in a direction perpendicular to the tangent at the tangent point on the first non-active tooth surface is decomposed into a force Ft in the tangent direction at the tangent point of the circle centered on the rotation axis of the first gear and passing through the tangent point, and a force Fr in the radial direction of the first gear. In this case, the magnitude of force Ft is greater than the magnitude of force Fr.

6. The gear set according to claim 1, characterized in that, The first gear or the second gear is a gear equipped with a pointer.

7. A movement, characterized in that The gear set includes any one of claims 1 to 6.

8. A clock, characterized in that, It includes the movement as described in claim 7.

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