Resin gear and gear device

Abstract

To improve the strength of a resin gear and a resin gear of a gear device. A molding material in which a reinforcing fiber (f) is mixed in a base resin (r) is used to form a first internal gear (22g) and a second internal gear (23g), on the meshing surface (221b, 231b) of each tooth, the reinforcing fiber is arranged along the tooth surface, and the fiber direction is irregular. Alternatively, on the meshing surface (221b, 231b) of each tooth, the reinforcing fiber is arranged along the tooth surface, and in the deep portion (d) overlapping the tooth surface when viewed in the circumferential direction, the fiber direction of the reinforcing fiber is irregular. The reinforcing fiber along the meshing surface (221b, 231b) helps to improve the strength of the meshing surface (221b, 231b).

Description

[0001] This application claims priority based on Japanese Patent Application No. 2020-196636, filed on November 27, 2020. The entire contents of that Japanese application are incorporated herein by reference. Technical Field

[0002] This invention relates to a resin gear and a gear assembly. Background Technology

[0003] In recent years, in accordance with the requirements for lightweight design, the use of resin-formed gears in gear systems has been encouraged.

[0004] In this type of resin gear, in order to improve strength, reinforcing fibers are mixed into the matrix resin, and the fiber direction of the reinforcing fibers is along the tooth surface and in the direction of the meshing surface of each tooth, while the fiber direction is set to be irregular in the tooth root (for example, see Patent Document 1).

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-218994

[0006] However, in the resin gear of Patent Document 1, there is room for improvement in terms of strength. Summary of the Invention

[0007] The purpose of this invention is to improve the strength of resin gears and gear assemblies.

[0008] This invention provides a resin gear, which is molded using a molding material made by mixing reinforcing fibers into a matrix resin, wherein...

[0009] On the meshing surface of each tooth, the reinforcing fibers are arranged along the tooth surface and the fiber direction is irregular.

[0010] Furthermore, the present invention provides a resin gear, which is formed using a molding material in which reinforcing fibers are mixed in a matrix resin, wherein the meshing surface of each tooth contains reinforcing fibers arranged along the tooth surface, and the fiber orientation of the reinforcing fibers is irregular in the deep portion overlapping the tooth surface when viewed circumferentially.

[0011] Furthermore, the present invention provides a gear device having an internal gear and an external gear, wherein,

[0012] One of the internal gears and the external gears is made of the aforementioned resin gear.

[0013] The internal gear and another of the external gears are made of metal.

[0014] According to the present invention, the strength of resin gears in resin gears and gear assemblies can be improved. Attached Figure Description

[0015] Figure 1 This is an axial sectional view showing the flexural meshing gear device according to an embodiment of the present invention.

[0016] Figure 2 This is a diagram showing one tooth of the internal gear in a flexural meshing gear mechanism viewed from the axial direction.

[0017] Figure 3 It means Figure 2 The diagram shows the direction of the reinforcing fibers in the matrix resin on the meshing surface, i.e., the surface cut along the UU line.

[0018] Figure 4 yes Figure 2 A cross-sectional view of the surface cut along the VV line, which is closer to the inner side of the tooth surface.

[0019] Figure 5 It is along the way Figure 2 A sectional view of the deep part of the interior cut along the WW line.

[0020] Figure 6 This is a diagram showing one tooth of the internal gear in a flexural meshing gear mechanism viewed from the axial direction.

[0021] Figure 7 It means Figure 6 The diagram shows the direction of the reinforcing fibers in the matrix resin on the tooth tip surface, i.e., the surface cut along line LL.

[0022] Figure 8 yes Figure 6 A sectional view of the surface cut along the MM line, which is closer to the inner side of the tooth tip.

[0023] Figure 9 yes Figure 6 A cross-sectional view of the surface along line NN, which is located more inside the tooth tip.

[0024] Figure 10 It means Figure 2 A diagram showing the orientation of the reinforcing fibers within the matrix resin in the rectangular region S within the axial end face.

[0025] In the diagram: 1-Gear assembly, 12-External gear, 23-Internal gear component, 221, 231-Teeth, 221a, 231a-Tooth top surface, 221b, 231b-Meshing surface, 221c, 231c-Tooth root surface, O1-Rotating shaft, d-Deep part, f-Reinforcing fiber, h / 2-Midpoint, r-Matrix resin. Detailed Implementation

[0026] [Brief Structure of the Implementation Method]

[0027] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Figure 1 This is a cross-sectional view showing the gear device (i.e., the flexural meshing gear device) involved in the embodiment.

[0028] Hereinafter, the direction along the rotation axis O1 in the figure will be defined as "axial", the direction perpendicular to the rotation axis O1 will be defined as "radial", and the rotation direction centered on the rotation axis O1 will be defined as "circumferential".

[0029] like Figure 1 As shown, the flexural meshing gear device 1 is a cylindrical flexural meshing gear device that transmits rotational motion centered on the rotating shaft O1 by flexing and deforming the external gear 12 (the second gear).

[0030] Specifically, the flexural meshing gear device 1 includes: a vibrating body shaft 10; an external gear 12, which is flexed and deformed by the vibrating body shaft 10; a first internal gear 22g and a second internal gear 23g, which mesh with the external gear 12; and a vibrating body bearing 15. The flexural meshing gear device 1 also includes a first housing 22, an internal gear component 23, a second housing 24, a first cover 26, a second cover 27, an input bearing 31, an input bearing 32, and a main bearing 33.

[0031] The vibratory shaft 10 is a hollow shaft and includes: a vibratory body 10A, with an elliptical cross-section perpendicular to the rotation axis O1; and shaft portions 10B and 10C, located on both sides of the vibratory body 10A along its axial direction and with circular cross-sections perpendicular to the rotation axis O1. Furthermore, the elliptical shape is not limited to a strictly geometrically defined ellipse, but includes approximate ellipses. The vibratory shaft 10 rotates around the rotation axis O1, and the center of the cross-section of the vibratory body 10A perpendicular to the rotation axis O1 coincides with the rotation axis O1. This vibratory shaft 10 serves as an input shaft for connecting to a drive source such as a motor (not shown) to input driving force.

[0032] The external gear 12 is a flexible cylindrical metal with teeth on its outer circumference.

[0033] The first internal gear 22g and the second internal gear 23g rotate around the vibrating body shaft 10 with the rotating shaft O1 as the center.

[0034] These first internal gears 22g and second internal gears 23g are arranged axially and mesh with the external gear 12. Specifically, one of the first internal gear 22g and the second internal gear 23g meshes with a tooth portion of the external gear 12 that is further to one side than the axial center, and the other meshes with a tooth portion of the external gear 12 that is further to the other side than the axial center. The first internal gear 22g is constructed by providing internal teeth at corresponding locations on the inner periphery of the first housing 22. The second internal gear 23g is constructed by providing internal teeth at corresponding locations on the inner periphery of the internal gear component 23.

[0035] A vibratory bearing 15 is disposed between the vibratory body 10A and the external gear 12. The vibratory bearing 15 has a plurality of rolling elements (rollers) 15A and a retainer 15C for holding the plurality of rolling elements 15A. The plurality of rolling elements 15A roll on the outer peripheral surface of the vibratory body 10A and the inner peripheral surface of the external gear 12 as rolling surfaces. Alternatively, the vibratory bearing 15 may also have an inner ring separate from the vibratory body 10A or an outer ring separate from the external gear 12.

[0036] Spacer rings 36 and 37 are respectively provided on both sides of the retainer 15C of the external gear 12 and the vibrating body bearing 15 in the axial direction to abut against them and restrict their axial movement as limiting components.

[0037] The first housing 22 and the second housing 24 are connected together by a connecting member (i.e., bolt 57), thereby covering the radially outer sides of the first internal gear 22g, the second internal gear 23g, and the external gear 12. As described above, internal teeth are provided on a portion of the inner periphery of the first housing 22, and the first housing 22 and the first internal gear 22g are integrally formed.

[0038] Furthermore, on the opposite load sides of the first housing 22 and the second housing 24 ( Figure 1 At the right end of the first housing 22, bolt holes 22h and 24h are provided, extending continuously along the axial direction. When the flexible meshing gear device 1 is connected to an external component 55 (e.g., the base arm component of a robot) outside the device, the first housing 22 and the second housing 24 are fastened together with the external component 55 via bolt holes 22h and 24h and by connecting components (i.e., bolts 53). These bolt holes 22h and 24h are provided at multiple locations in the circumferential direction. Furthermore, the first housing 22 and the second housing 24 also have bolt holes 22j and 24j that are different from the bolt holes 22h and 24h. The first housing 22 and the second housing 24 are connected together (temporarily fixed) by inserting and screwing the bolts 57 into the bolt holes 22j and 24j.

[0039] At least a portion of the internal gear component 23 is disposed radially inside the second housing 24 and radially outside the vibrating body shaft 10. Furthermore, as described above, internal teeth are provided on a portion of the inner circumference of the internal gear component 23, and the internal gear component 23 is integrally formed with the second internal gear 23g.

[0040] The first cover 26 and the first outer shell 22 have bolt holes 26k and 22k respectively on the opposite side of the load. The first cover 26 and the first outer shell 22 are connected together by bolts 51 that are inserted through and screwed into the bolt holes 26k and 22k.

[0041] Furthermore, the first cover 26 covers the outer periphery of one end of the vibrating body shaft 10.

[0042] The second cover 27 is connected to the internal gear component 23 and covers the outer periphery of the other end of the vibrating body shaft 10. On the load side of the second cover 27 and the internal gear component 23 ( Figure 1 At the left end of the device, bolt holes 27h and 23h are provided, extending continuously along the axial direction. When the flexible meshing gear device 1 is connected to the driven component 56 (e.g., the front end arm component of a robot) outside the device, the second cover 27 and the internal gear component 23 are fastened together with the driven component 56 via the bolt holes 27h and 23h and by connecting components (i.e., bolts 54). These bolt holes 27h and 23h are provided at multiple locations in the circumferential direction. Furthermore, the second cover 27 and the internal gear component 23 also have bolt holes 27j and 23j that are different from the bolt holes 27h and 23h. By inserting and screwing bolts 52 into these bolt holes 27j and 23j, the second cover 27 and the internal gear component 23 are connected together (temporarily fixed).

[0043] The input bearing 31 is, for example, a ball bearing having an inner ring 31a, an outer ring 31b, and rolling elements 31c, and is disposed between the shaft portion 10B of the vibrator shaft 10 and the first housing 26. The first housing 26 supports the vibrator shaft 10 for free rotation via the input bearing 31. Furthermore, the input bearing 31 is not limited to a ball bearing; various bearings can be used, such as roller bearings. Also, it is possible to form the inner ring integrally with the vibrator shaft 10 or the outer ring integrally with the first housing 26 without the need for a dedicated inner or outer ring.

[0044] The input bearing 32 is, for example, a ball bearing having an inner ring 32a, an outer ring 32b, and rolling elements 32c, and is disposed between the shaft portion 10C of the vibrator shaft 10 and the second housing 27. The second housing 27 supports the vibrator shaft 10 for free rotation via the input bearing 32. Furthermore, the input bearing 32 is not limited to a ball bearing; various bearings can be used, such as roller bearings. Also, it is possible to form the inner ring integrally with the vibrator shaft 10 or the outer ring integrally with the second housing 27 without the need for a dedicated inner or outer ring.

[0045] Furthermore, both input bearings 31 and 32 are bearings with seals containing lubricant inside, but they may also be bearings without seals.

[0046] The main bearing 33 is, for example, a ball bearing having an inner ring 33a, an outer ring 33b, and rolling elements 33c, and is disposed between the internal gear component 23 and the second housing 24. The second housing 24 supports the internal gear component 23 for free rotation via the main bearing 33. Furthermore, the main bearing 33 is not limited to a ball bearing and can be various types of bearings. For example, crossed roller bearings can be used, or it can be composed of multiple bearings (angular contact ball bearings, tapered bearings, etc.) axially separated between the internal gear component 23 and the second housing 24. Moreover, the main bearing 33 may not require a dedicated inner or outer ring; the inner ring may be integrally formed with the internal gear component 23, or the outer ring may be integrally formed with the second housing 24. Furthermore, the main bearing 33 is not particularly limited, but it can also be a bearing with a seal containing lubricant.

[0047] On the axially outer side of the lubricant sealing space S of the input bearings 31, 32 and main bearing 33 relative to the mechanism portion that houses the flexural meshing gear device 1, shaft seals (i.e., seals 41 to 43) are provided to ensure the sealing of these bearings.

[0048] The sealing portion 41 of the input bearing 31 is formed by a wall surface that extends radially inward from the first cover 26 to near the outer peripheral surface of the vibrator shaft 10 (shaft portion 10B) and thus covers the axial outer side of the input bearing 31. A narrow gap is formed between the sealing portion 41 and the outer peripheral surface of the shaft portion 10B, thereby hindering the movement of lubricant.

[0049] The sealing portion 42 of the input bearing 32 is formed by a wall surface that extends radially inward from the second cover 27 to near the outer peripheral surface of the vibrator shaft 10 (shaft portion 10C) and thus covers the axial outer side of the input bearing 32. A narrow gap is formed between the sealing portion 42 and the outer peripheral surface of the shaft portion 10C, thereby hindering the movement of lubricant.

[0050] The sealing portion 43 of the main bearing 33 is formed by a wall surface extending radially inward from the second housing 24 to near the outer peripheral surface of the second cover 27, thereby covering the axially outer side of the main bearing 33. A narrow gap is formed between the sealing portion 43 and the outer periphery of the second cover 27, thereby hindering the movement of lubricant. Furthermore, on the inner side of the sealing portion 43 (the main bearing 33 side), there is a protrusion protruding radially outward from the second cover 27. These sealing portions 43 and protrusions constitute a labyrinth structure.

[0051] [Action Description]

[0052] In the flexural meshing gear device 1 described above, if the vibrating body shaft 10 is driven to rotate by a drive source such as a motor, the motion of the vibrating body 10A will be transmitted to the external gear 12. At this time, the external gear 12 meshes with the fixed first internal gear 22g at the long axis position of the vibrating body 10A. Therefore, the external gear 12 does not rotate at the same speed as the vibrating body 10A, but moves based on the long axis position of the flexurally deformed vibrating body 10A.

[0053] For example, if the number of teeth of the external gear 12 is set to 100 and the number of teeth of the first internal gear 22g is set to 102, then for each revolution in the meshing position, the external gear 12 rotates (rotates) by the amount corresponding to the difference in the number of teeth between the external gear 12 and the first internal gear 22g. If the number of teeth is set as described above, the rotational motion of the vibrating body shaft 10 is reduced to a reduction ratio of 100:2 and then transmitted to the external gear 12.

[0054] On the other hand, the external gear 12 also meshes with the second internal gear 23g. Therefore, for example, if the number of teeth of the second internal gear 23g is set to the same number as the number of teeth of the external gear 12, the external gear 12 and the second internal gear 23g rotate at the same speed, and this rotational motion is output to the driven component 56.

[0055] [Materials of each component]

[0056] In this embodiment, the materials of each component are as follows.

[0057] The vibrating body shaft 10, external gear 12, and spacers 36 and 37 are made of metal materials such as steel. While not particularly restricted, more specifically, the vibrating body shaft 10 is made of steel materials such as chromium-molybdenum steel. The external gear 12 is made of steel materials such as nickel-chromium-molybdenum steel. The spacers 36 and 37 are made of steel materials such as high-carbon chromium bearing steel.

[0058] Furthermore, in the input bearings 31, 32 and the main bearing 33, the inner and outer rings and rolling elements are made of metal (e.g., high carbon chromium bearing steel).

[0059] Furthermore, in the vibrating body bearing 15, the rolling elements 15A and the retainer 15C are made of metal (e.g., high carbon chromium bearing steel).

[0060] Furthermore, each bolt 51 to 54 and 57 is made of metal (e.g., rolled steel for general structures, cold-forged carbon steel wire, carbon structural steel for machinery, etc.).

[0061] On the other hand, the first outer shell 22, the internal gear component 23, the second outer shell 24, the first cover 26, and the second cover 27 are made of resin.

[0062] In this embodiment, the resins used for the second outer shell 24, the first cover 26, and the second cover 27 are resins whose matrix contains reinforcing fibers. Alternatively, resins without reinforcing fibers may also be used.

[0063] The resin used as the matrix material is, for example, an engineering plastic (general-purpose engineering plastic) with heat resistance of 50–60°C. Specifically, examples include polyamide (PA), polycarbonate (PC), polyaldehyde resin (POM), modified polyphenylene ether (m-PPE), and polybutylene terephthalate (PBT). The heat resistance mentioned here refers to the temperature at which the gear maintains its performance, not the temperature at which it maintains its static shape.

[0064] Furthermore, examples of reinforcing fibers include glass fiber, aramid fiber, polyethylene fiber, cyclohexene fiber, and boron fiber. When using general-purpose engineering plastics containing these fibers (e.g., polyaldehyde resin containing glass fiber), the thermal conductivity is less than 0.3 W / m℃.

[0065] In this embodiment, the resin used for the first housing 22 and the internal gear component 23 is a resin whose resin matrix material contains reinforcing fibers.

[0066] The resin used as the matrix material is preferably a resin with heat resistance of 70°C or higher, for example, a super engineering plastic (special engineering plastic) with heat resistance of 100°C or higher. Specifically, examples include polyetheretherketone (PEEK), polyamide-imide (PAI), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), aromatic polyamide (PPA), liquid crystal polymer (LCP), polysulfone (PSU), polyethersulfone (PES), polyetherimide (PEI), polyarylate (PAR), and thermoplastic polyimide (TPI).

[0067] Furthermore, as the reinforcing fiber, a fiber with higher thermal conductivity than the aforementioned reinforcing fibers is used, such as carbon fiber. The thermal conductivity of the high thermal conductivity resin component is preferably 0.5 W / m℃ or higher, and in the case of using a super engineering plastic (e.g., polyetheretherketone) containing carbon fiber, the thermal conductivity is 0.95 W / m℃.

[0068] Furthermore, regarding the resin and reinforcing fibers used in the first housing 22 and the internal gear component 23, considering heat dissipation, resins and reinforcing fibers with higher thermal conductivity or heat resistance than those of the second housing 24, the first cover 26, and the second cover 27 are selected. However, the same resins and reinforcing fibers used in the first housing 22 and the internal gear component 23 as those exemplified in the second housing 24, the first cover 26, and the second cover 27 may also be used.

[0069] [Regarding the fiber orientation in gears]

[0070] As described above, the first housing 22 and the internal gear component 23 are made of resin and reinforcing fibers (hereinafter referred to as reinforcing fibers), and the first internal gear 22g and the second internal gear 23g formed on their inner periphery are also made of resin and reinforcing fibers. Both the first internal gear 22g and the second internal gear 23g are resin gears.

[0071] The first internal gear 22g and the second internal gear 23g have features not previously known in the longitudinal direction (i.e., fiber direction) of the reinforcing fibers in the resin (called matrix resin) that forms these gears.

[0072] In the first internal gear 22g and the second internal gear 23g, the internal teeth are composed of a plurality of teeth 221 and 231 arranged at equal intervals along the inner circumference. Figure 2 This is a diagram showing the view of one tooth 221 or 231 from the axial direction. Furthermore, although there are slight differences in the dimensions or other parts of tooth 221 of the first internal gear 22g and tooth 231 of the second internal gear 23g, their structures are essentially the same. Therefore, in Figure 2 and the internal structure described later Figures 3 to 10 Only one gear is shown in the diagram. In these diagrams, the symbol for tooth 231 of the second internal gear 23g is enclosed in parentheses.

[0073] The teeth 221 and 231 of the first internal gear 22g and the second internal gear 23g each have a tooth tip surface 221a and 231a that extends approximately circumferentially at their innermost radial direction. Furthermore, each tooth 221 and 231 has a meshing surface 221b and 231b that are adjacent to both sides of the tooth tip surface 221a and 231a in the circumferential direction. Additionally, tooth root surfaces 221c and 231c are located on the outer side of the meshing surfaces 221b and 231b in the circumferential direction (in a direction circumferentially away from the tooth tip surface 221a and 231a) and between teeth 221 and 231.

[0074] In addition, regarding the tooth tip surfaces 221a and 231a, the meshing surfaces 221b and 231b, and the tooth root surfaces 221c and 231c, Figure 2 The surface is typically flat, but it is not limited to this; it can also be composed of curved surfaces.

[0075] Figure 3 It means Figure 2 The diagram shows the direction of the reinforcing fibers f in the matrix resin r on the meshing surfaces 221b and 231b, which are the tooth surfaces cut along the UU line (or the interior of the tooth surface that is close to the tooth surface). Figure 4 yes Figure 2 A cross-sectional view of the surface (parallel to the tooth surface) cut along the VV line, which is located more inside the tooth surface (within the matrix resin r). Figure 5 It is along the way Figure 2 A sectional view on the surface (parallel to the tooth surface) cut by the WW line at the depth d in the middle.

[0076] Additionally, the depth d refers to the depth that overlaps with the meshing surfaces 221b and 231b when viewed from the circumferential direction. That is, the depth d refers to the position as follows: when the circumferential surface p is defined as the circumferential surface at the midpoint h / 2 of the full tooth height h in the radial direction of teeth 221 and 231, the circumferential surface p is the midpoint in the circumferential direction between the positions of the meshing surfaces 221b and 231b on both sides of the circumferential direction of teeth 221 and 231.

[0077] and, Figure 4 The surface cut along line VV corresponds to the depth at the central position between the meshing surfaces 221b and 231b and the deep part d.

[0078] Figures 2-4 The reinforcing fibers f depicted as lines indicate that their fiber direction is along the meshing surfaces 221b and 231b. The more inclined the reinforcing fibers f are relative to the meshing surfaces 221b and 231b, the shorter their length appears. Furthermore, the reinforcing fibers f depicted as dots indicate that their fiber direction is significantly inclined relative to the meshing surfaces 221b and 231b.

[0079] Here, "reinforcing fiber f along a certain surface" means that in a cross-section on or parallel to a certain surface, the reinforcing fiber f appears as a line. The certain surface can be the meshing surface, tooth tip surface, axial end face, etc. Furthermore, "the reinforcing fiber f appears as a line" means that the reinforcing fiber f has both a length direction and a width direction, with the length dimension being more than three times larger than the width dimension.

[0080] like Figure 3As shown, on or near the meshing surfaces 221b and 231b of teeth 221 and 231, most of the reinforcing fibers f are linear, indicating that the fiber direction of these reinforcing fibers f is along the meshing surfaces 221b and 231b. For example, in this embodiment, the area occupied by the reinforcing fibers f along the tooth surface is 10% or more, preferably 30% or more (the same applies to the tooth tip surfaces 221a and 231a and the axial end faces described later). In addition, although the fiber direction (length direction) of these reinforcing fibers f is along the meshing surfaces 221b and 231b, they are oriented in an irregular (random) direction within these surfaces.

[0081] Here, "irregular" means that the reinforcing fibers f are not oriented in the same direction, and that the reinforcing fibers f are generally oriented in different directions. For example, if the deviation (angle less than 90 degrees) of the angle (the angle difference between the reinforcing fiber with the largest angle and the reinforcing fiber with the smallest angle) between a certain direction (e.g., the tooth direction) and the fiber direction (length direction) of each reinforcing fiber f is 45 degrees or more, it can be called "irregular".

[0082] In the aforementioned meshing surfaces 221b and 231b, a state is shown in which the fibers are oriented in different directions within the surface, provided that they are along the meshing surfaces 221b and 231b. However, without mentioning this premise, "irregular" means that the reinforcing fibers f are not along a surface and are generally oriented in different directions.

[0083] In addition, in the above Figure 3 The lower part contains dot-like reinforcing fibers f (reinforcing fibers f that do not follow the meshing surfaces 221b and 231b). This part is a region that is radially outward (inside the matrix resin r) than the tooth root surfaces 221c and 231c, and is a portion separated from the meshing surfaces 221b and 231b. In other words, it is a portion that does not overlap with the meshing surfaces 221b and 231b when viewed circumferentially. Thus, in this embodiment, in the tooth surface sectioned along the UU line, the boundary between the region where the reinforcing fibers f follow the tooth surface and the region where the reinforcing fibers f do not follow the tooth surface is clearly visible.

[0084] On the other hand, in the central position between the meshing surfaces 221b and 231 of teeth 221 and 231 and the deep part d, such as Figure 4 As shown, the reinforcing fibers f that appear as dots are mixed with the reinforcing fibers f that appear as lines, and the reinforcing fibers f along the meshing surfaces 221b and 231b become less than the reinforcing fibers along the meshing surfaces 221b and 231b.

[0085] Moreover, in the deep part d of the meshing surfaces 221b and 231b, far from the teeth 221 and 231, such as Figure 5As shown, the majority of reinforcing fibers f are dot-like, while the fewest are linear and shorter. Specifically, in the deeper region d of the meshing surfaces 221b and 231b, away from teeth 221 and 231, the reinforcing fibers f along the meshing surfaces 221b and 231b are fewer than those along the meshing surfaces 221b and 231b at the central position, resulting in an irregular state where each fiber direction is oriented in various three-dimensional directions. Furthermore, in the central position and the deeper region d, the boundary between the areas where reinforcing fibers f are along the tooth surface and the areas where reinforcing fibers f are not along the tooth surface is not distinct. As described above, in this embodiment, the number of reinforcing fibers f along the meshing surfaces 221b and 231b gradually decreases from the meshing surfaces 221b and 231b towards the deeper region d.

[0086] Next, the fiber direction of the reinforcing fiber f on the tooth tip surfaces 221a and 231a of teeth 221 and 231 will be explained. Figure 6 This is a diagram showing teeth 221 and 231 viewed from the axial direction. Figure 7 It means Figure 6 A diagram showing the direction of the reinforcing fibers f in the matrix resin r on the tooth tip surfaces 221a and 231a (or the interior infinitely close to the tooth tip surfaces 221a and 231a), i.e., on the surface cut along line LL. Figure 8 yes Figure 6 A cross-sectional view of the surface (parallel to tooth tips 221a and 231a) cut along the MM line, which is located more inside the tooth tip surfaces 221a and 231a (within the matrix resin r). Figure 9 yes Figure 6 A cross-sectional view of the surface (parallel to tooth tips 221a and 231a) cut along line NN, which is located more inside the tooth tip surfaces 221a and 231a (within the matrix resin r).

[0087] in addition, Figure 8 The depth of the MM line relative to the tooth tip surfaces 221a and 231a is the same as the above. Figure 4 The depths of the VV lines relative to the meshing surfaces 221b and 231b are consistent (at the center position between the LL line and the NN line). Furthermore, Figure 9 The depth of the NN line relative to the tooth tip surfaces 221a and 231a is the same as the above. Figure 5 The depth of the WW line relative to the meshing surfaces 221b and 231b is consistent (central position in the tooth height direction).

[0088] Depend on Figure 7It can be seen that on or near the tooth tip surfaces 221a and 231a of teeth 221 and 231, most of the reinforcing fibers f are linear, and these reinforcing fibers f are along the tooth tip surfaces 221a and 231a. In addition, similar to the case of meshing surfaces 221b and 231b, in the tooth tip surfaces 221a and 231a, the fiber direction (length direction) of the reinforcing fibers f is also irregularly oriented within the surfaces 221a and 231a.

[0089] On the other hand, it can also be seen that slightly inside the tooth tip surfaces 221a and 231a of teeth 221 and 231 (at the position of the MM line), such as Figure 8 As shown, the dotted reinforcing fibers f are mixed with the linear reinforcing fibers f, and the number of reinforcing fibers f along the tooth tip surfaces 221a and 231a is not increased. That is, the reinforcing fibers f along the tooth tip surfaces 221a and 231a are less than the reinforcing fibers along the tooth tip surfaces 221a and 231a.

[0090] Furthermore, at positions further away from the tooth tip surfaces 221a and 231a (the positions of the NN lines), such as Figure 9 As shown, the majority of reinforcing fibers f appear as dots, while the number of reinforcing fibers f appearing as lines is smaller and shorter. That is, at positions away from the tooth tip surfaces 221a and 231a of teeth 221 and 231, the reinforcing fibers f do not follow the tooth tip surfaces 221a and 231a but become irregular in that their directions are oriented in various directions. At the position of the NN line, there are fewer reinforcing fibers f along the tooth tip surfaces 221a and 231a than at the position of the MM line.

[0091] In addition, Figure 8 and Figure 9 In the middle, on the axial end faces of the first internal gear 22g and the second internal gear 23g ( Figure 8 and Figure 9 Near the upper and lower ends, the ratio of the reinforcing fibers f that appear as dots becomes higher, which is due to the reinforcing fibers f along the axial end faces near the axial end faces of the first internal gear 22g and the second internal gear 23g.

[0092] Next, the fiber direction of the reinforcing fiber f on the axial end face of teeth 221 and 231 will be explained. Figure 10 It means Figure 2 A diagram showing the orientation of reinforcing fibers f within the matrix resin r in a rectangular region S within the axial end face (or the interior infinitely close to the axial end face).

[0093] Depend on Figure 10It can be seen that on or near the axial end faces of teeth 221 and 231, most of the reinforcing fibers f are linear, and these reinforcing fibers f are along the axial end faces. In addition, although the reinforcing fibers f are also along the axial end faces, each reinforcing fiber f is oriented in a different direction within this plane, resulting in an irregular state.

[0094] [Gear Forming]

[0095] The aforementioned first internal gear 22g and second internal gear 23g can be molded using an injection molding apparatus, which includes: a hopper for supplying resin material (either as integral granules of the matrix resin r and the reinforcing fiber f, or as separate granules of the matrix resin r and the reinforcing fiber f) to the matrix resin r; a heater for heating the supplied resin material to plasticize it; a screw for mixing the plasticized resin material and the reinforcing fiber f; a cylinder for injecting the mixed resin material and the reinforcing fiber f; a pair of molds having cavities corresponding to the shape of the first internal gear 22g or the second internal gear 23g; and a mold holding mechanism for holding pressure on the pair of molds.

[0096] Through the above-mentioned molding device, the resin material of the matrix resin r supplied from the hopper to the cylinder is heated together with the reinforcing fiber f by the heater, and the plasticized resin material and reinforcing fiber f are mixed by the screw.

[0097] Next, the mixed resin material and reinforcing fiber f are injected from the cylinder into the cavity of a pair of molds held under pressure by the mold holding mechanism. After the resin material cools, the pair of molds are opened, and the first internal gear 22g or the second internal gear 23g is taken out from the cavity, thus completing the molding.

[0098] Alternatively, the molding conditions in the above-mentioned injection molding can be appropriately adjusted to form a first internal gear 22g or a second internal gear 23g with teeth 221 or 231 in a more preferred fiber direction having reinforcing fibers f.

[0099] Furthermore, the injection molding of the first internal gear 22g or the second internal gear 23g can also be carried out in two stages.

[0100] For example, the first internal gear 22g or the second internal gear 23g of the first stage is formed using a mold with a cavity designed to be slightly smaller with the outer dimensions of the teeth 221 or 231. Then, the second stage of injection molding is performed using a mold with a cavity designed to be the correct size with the outer dimensions of the teeth 221 or 231 to fill the gaps generated in the meshing surfaces 221b, 231b, tooth top surfaces 221a, 231a, axial end faces, etc. in the cavity, so that the fiber direction of the reinforcing fiber f is better along each surface.

[0101] Alternatively, the positions corresponding to the meshing surfaces 221b, 231b, tooth tip surfaces 221a, 231a, and axial end faces of the first internal gear 22g or the second internal gear 23g formed in the first stage above can be treated with reinforcing fiber f spraying, and then the gaps generated at the positions corresponding to the axial end faces, etc., can be filled with plasticized resin material in the second stage of injection molding.

[0102] [Technical Effects of This Embodiment]

[0103] In the aforementioned flexural meshing gear device 1, the first internal gear 22g and the second internal gear 23g are made of a molding material formed by mixing reinforcing fibers f in a matrix material of a matrix resin r. The meshing surfaces 221b and 231b of each tooth 221 and 231 contain reinforcing fibers f arranged along the tooth surface, and the fiber direction of the reinforcing fibers arranged along the tooth surface is irregular.

[0104] With this fiber structure, the bending strength, fatigue strength, and shear resistance of the meshing surfaces 221b and 231b of the teeth 221 and 231 of the first internal gear 22g and the second internal gear 23g can be improved, and the meshing surfaces 221b and 231b can be strengthened in multiple directions along the meshing surfaces 221b and 231b.

[0105] In contrast, when the reinforcing fibers f along the meshing surfaces 221b and 231b are all oriented in a certain direction, the meshing surfaces 221b and 231b are only reinforced in that direction, and cannot be reinforced in other directions. Moreover, if the reinforcement direction is so concentrated in one direction, the strength difference in that direction between the meshing surfaces 221b and 231b and the root surfaces 221c and 231c will become too large, which may cause tooth breakage along the root circle.

[0106] On the other hand, when the reinforcing fiber f is along the meshing surfaces 221b and 231b of each tooth 221 and 231 and the fiber direction is irregular, the strength difference in a certain direction between the meshing surfaces 221b and 231b and the root surfaces 221c and 231c can be reduced, and the breakage of the teeth 221 and 231 can be suppressed.

[0107] Furthermore, in the teeth 221 and 231 of the first internal gear 22g and the second internal gear 23g, in the deep part d that overlaps with the meshing surfaces 221b and 231b when viewed from the circumferential direction, the fiber direction of the reinforcing fiber f is irregular and does not follow the meshing surfaces 221b and 231b.

[0108] At this time, the surface strength on the meshing surfaces 221b and 231b of each tooth 221 and 231 can be improved, and the strength difference between the inner side of the meshing surfaces 221b and 231b and the root surfaces 221c and 231c can be reduced, which can further effectively suppress the breakage of teeth 221 and 231.

[0109] Furthermore, in the above Figure 4 At the central position between the meshing surfaces 221b and 231b of the teeth 221 and 231 and the depth d, the proportion of reinforcing fibers f along the tooth surfaces 221b and 231b is less than that along the tooth surfaces 221b and 231b.

[0110] Therefore, the range from the meshing surfaces 221b and 231b to the depth d becomes a structure in which the proportion of reinforcing fibers f decreases along the tooth surface of the meshing surfaces 221b and 231b. This reduces the strength difference between the meshing surfaces 221b and 231b and their inner surfaces, and effectively suppresses peeling, fracture, and cracking on the inner surfaces of the meshing surfaces 221b and 231b.

[0111] Furthermore, in the above Figure 5 The proportion of reinforcing fibers f along the tooth surfaces of the meshing surfaces 221b and 231b in the deep part d of the teeth 221 and 231b is less than that along the meshing surfaces 221b and 231b in the central position.

[0112] Therefore, the range from the meshing surfaces 221b and 231b through the central position to the depth d becomes a structure in which the proportion of reinforcing fibers f decreases along the tooth surface of the meshing surfaces 221b and 231b. This can further reduce the strength difference between the meshing surfaces 221b and 231b and their inner sides, and can more effectively suppress peeling, fracture, and cracking on the inner sides of the meshing surfaces 221b and 231b.

[0113] Furthermore, the first internal gear 22g and the second internal gear 23g contain reinforcing fibers f arranged along the tooth tip surfaces 221a and 231a of each tooth 221 and 231.

[0114] This improves the bending strength, fatigue strength, and shear resistance of the tooth tip surfaces 221a and 231a, and strengthens them in all directions along the tooth tip surfaces 221a and 231a. Therefore, it not only improves the strength of the meshing surfaces 221b and 231b, but also strengthens each tooth 221 and 231 as a whole.

[0115] Furthermore, the first internal gear 22g and the second internal gear 23g each contain reinforcing fibers f arranged along the axial end face of each tooth 221, 231.

[0116] This improves the bending strength, fatigue strength, and shear resistance of the axial end face, and strengthens it in multiple directions along the axial end face.

[0117] Moreover, it can not only improve the strength of the meshing surfaces 221b and 231b and the tooth tip surfaces 221a and 231a, but also further strengthen each tooth 221 and 231 as a whole.

[0118] Furthermore, in the flexural meshing gear device 1, the first internal gear 22g and the second internal gear 23g are resin gears with the inherent structure of the aforementioned reinforcing fiber f, and the external gear 12 is a gear made of metal. Therefore, while achieving a lightweight device, the overall durability of the device can be improved by strengthening the first internal gear 22g and the second internal gear 23g.

[0119] [other]

[0120] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments.

[0121] For example, in each tooth 221 and 231 of the first internal gear 22g and the second internal gear 23g, the fiber direction is irregular in the depth d of the meshing surfaces 221b and 231b, which improves the suppression effect of fracture and crack along the tooth root circle.

[0122] Thus, even if the fiber direction of the reinforcing fiber f is irregular in the deep part d, the reinforcing fibers f on the meshing surfaces 221b and 231b can be arranged along the tooth surface and the fiber directions can be the same. At this time, even if the strength difference in a certain direction between the meshing surfaces 221b and 231b and the tooth root surfaces 221c and 231c increases, the strength difference between the inner side of the meshing surfaces 221b and 231b and the inner side of the tooth root surfaces 221c and 231c will be sufficiently reduced, thus effectively suppressing the generation of fractures and cracks along the tooth root circle.

[0123] Furthermore, in the above embodiment, the characteristic structure in the fiber direction of the reinforcing fiber f in the matrix resin r is applied to each tooth 221, 231 of the first internal gear 22g and the second internal gear 23g of the flexural meshing gear device 1. However, the characteristic structure in the fiber direction of the reinforcing fiber f can also be applied to the external gear, and the above-mentioned characteristic structure in the fiber direction of the reinforcing fiber can also be applied to each tooth of the resin gear of all types of gear mechanisms other than the flexural meshing gear device 1.

[0124] Furthermore, in the case of various gear mechanisms in which the internal gear and the external gear mesh with each other, either the internal gear or the external gear can be a metal gear, and the other gear can be a resin gear with the aforementioned characteristic structure in the fiber direction of the reinforcing fiber.

[0125] Furthermore, the details shown in the above embodiments can be appropriately modified without departing from the spirit of the invention.

Claims

1. A resin gear, which is molded using a molding material made by mixing reinforcing fibers into a matrix resin, characterized in that, The meshing surface of each tooth includes reinforcing fibers arranged along the tooth surface, and the fiber direction of the reinforcing fibers located on the tooth surface is along the tooth surface and faces an irregular direction within the tooth surface. In the deep portion overlapping the tooth surface when viewed circumferentially, the fiber orientation of the reinforcing fibers is irregular in three dimensions.

2. The resin gear according to claim 1, characterized in that, In the tooth surface, the boundary between the area where the reinforcing fiber is along the tooth surface and the area where the reinforcing fiber is not along the tooth surface is shown.

3. The resin gear according to claim 1 or 2, characterized in that, At the central position between the deep portion overlapping the tooth surface of the meshing surface when viewed circumferentially and the tooth surface of the meshing surface, the proportion of reinforcing fibers along the tooth surface of the meshing surface is less than the proportion of reinforcing fibers along the tooth surface of the meshing surface.

4. The resin gear according to claim 3, characterized in that, In the deeper region, the proportion of reinforcing fibers along the tooth surface of the meshing surface is less than the proportion of reinforcing fibers along the tooth surface of the meshing surface at the central location.

5. The resin gear according to claim 1 or 2, characterized in that, The tooth tip surface of each tooth contains reinforcing fibers arranged along the tooth tip surface.

6. The resin gear according to claim 1 or 2, characterized in that, Each tooth has reinforcing fibers arranged along its axial end face.

7. A gear mechanism having an internal gear and an external gear, characterized in that, One of the internal gears and the external gears is made of a resin gear as described in any one of claims 1 to 6. The internal gear and the other gear of the external gear are made of metal.

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