Gear device

Abstract

To suitably apply a carbon fiber reinforced resin to a gear material.SOLUTION: A gear device (1) comprises an external gear (12), and a first internal gear (22) and a second internal gear (23) engaged with the external gear (12). The external gear (12) is made of a metal. The first internal gear (22) and the second internal gear (23) are made of a carbon fiber reinforced resin.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a gear device. [Background technology]

[0002] In recent years, there has been an increase in the use of resin materials as gear materials, mainly for the purpose of reducing weight (see, for example, Non-Patent Document 1). When making a gear from a resin material, it is desirable to use a fiber-reinforced resin, which can increase strength, and in particular a carbon fiber-reinforced resin, which uses carbon fiber as the reinforcing fiber. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Yasuyuki Hashimoto and 3 others, "Development of High-Strength Plastic Gear Materials", Shin-Kobe Technical Report, Shin-Kobe Electric Machinery Co., Ltd., February 2006, No. 16, p10-15 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as described in Non-Patent Document 1 above, if carbon fiber reinforced resin is simply applied to externally meshing gears, the carbon fibers exposed on the tooth surfaces will attack the mating gear, causing early damage to both the resin gear and the mating gear.

[0005] The present invention has been made in view of the above circumstances, and has an object to suitably apply carbon fiber reinforced resin to a gear material. [Means for solving the problem]

[0006] The present invention provides a gear device including an external gear and an internal gear meshing with the external gear, The external gear is made of metal, The internal gear is made of carbon fiber reinforced resin.

[0007] The present invention also provides a gear device including an external gear and an internal gear meshing with the external gear, The internal gear is made of metal, The external gear is made of carbon fiber reinforced resin. Effect of the Invention

[0008] According to the present invention, a carbon fiber reinforced resin material can be suitably used as a gear material. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a cross-sectional view showing a gear device according to an embodiment. [Diagram 2] FIG. 11 is a cross-sectional view showing a gear device according to a modified example of the embodiment. [Diagram 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0011] [Gear system configuration] FIG. 1 is a cross-sectional view showing a gear device 1 according to this embodiment. As shown in this figure, the gear device 1 is a cylindrical flexure mesh type gear device and includes a vibration exciter shaft 10, an external gear 12, a first internal gear 22, a second internal gear 23, and a vibration exciter bearing 15. Furthermore, the gear device 1 includes a casing 24, a first cover 26, a second cover 27, input bearings 31 and 32, and a main bearing 33.

[0012] The vibrator shaft 10 is a hollow cylindrical shaft that rotates around a rotation axis O1, and has a vibrator 10A whose cross section perpendicular to the rotation axis O1 has a non-circular (e.g., elliptical) outer shape, and shaft portions 10B and 10C provided on both sides of the vibrator 10A in the axial direction. The elliptical shape is not limited to a geometrically strict ellipse, but includes an approximate ellipse. The shaft portions 10B and 10C are shafts whose cross section perpendicular to the rotation axis O1 has a circular outer shape. A driving source such as a motor (not shown) is connected to the vibrator shaft 10 to input a driving force. In the following description, the direction along the rotation axis O1 is referred to as the "axial direction", the direction perpendicular to the rotation axis O1 is referred to as the "radial direction", and the direction of rotation about the rotation axis O1 is referred to as the "circumferential direction". Additionally, in the axial direction, the side where the decelerated rotational motion is output (the left side in the drawing) is referred to as the "output side", and the side opposite the output side (the right side in the drawing) is referred to as the "anti-output side".

[0013] The external gear 12 is a flexible cylindrical member centered on the rotation axis O1, and has teeth on its outer periphery.

[0014] The vibrator bearing 15 is disposed between the vibrator 10A and the external gear 12. The vibrator bearing 15 has a plurality of rolling elements (rollers) 15A and a cage 15C that holds the plurality of rolling elements 15A. The plurality of rolling elements 15A roll with the outer peripheral surface of the vibrator 10A and the inner peripheral surface of the external gear 12 as rolling surfaces (also called raceway surfaces). The vibrator bearing 15 may have an inner ring separate from the vibrator 10A, an outer ring separate from the external gear 12, or both.

[0015] Spacer rings 36, 37 are provided on both axial sides of the external gear 12 and the vibration exciter bearing 15 in contact therewith to serve as restricting members for restricting their axial movement.

[0016] The first internal gear 22 and the second internal gear 23 have teeth 22g and 23g on their inner circumferences, respectively. The teeth 22g and 23g are aligned in the axial direction, with one meshing with the teeth of the external gear 12 on one side from the axial center, and the other meshing with the teeth of the external gear 12 on the other side from the axial center.

[0017] The outer periphery of the first internal gear 22 functions as a casing that covers the inside of the gear device 1 together with the casing 24. The anti-output side of the first internal gear 22 has a protruding portion for connection to the first cover 26, and a connecting hole 22h3 is provided in which a connecting member (bolt, etc., the same applies below) 51 for connecting to the first cover 26 is screwed. Furthermore, the first internal gear 22 is provided on its outer periphery with a connecting hole 22h1 for connecting to the casing 24 via a connecting member 53, and a connecting hole 22h2 for connecting to an external support member by tightening together with the casing 24. The connecting holes 22h1 to 22h3 are formed with female threads when a connecting member is screwed in, but no female threads are required when a connecting member is passed through.

[0018] The second internal gear 23 has a connection hole 23h1 for connection with an external member to be driven, and a connection hole 23h2 for connection with the second cover 27.

[0019] The casing 24 is connected to the first internal gear 22 via a connecting member 53. The casing 24 covers, together with the first internal gear 22, the radial outside of a portion where the teeth 22g, 23g of the first internal gear 22 and the second internal gear 23 mesh with the external gear 12. The casing 24 has a connecting hole 24h1 with which the connecting member 53 screws into, and a connecting hole 24h2 that communicates with the connecting hole 22h2 of the first internal gear 22.

[0020] The first cover 26 covers the outer periphery on the anti-output side of the vibration exciter shaft 10. The first cover 26 has a connecting hole 26h1 that communicates with the connecting hole 22h3 of the first internal gear 22, and is connected to the first internal gear 22 via a connecting member 51.

[0021] The second cover 27 covers the outer periphery on the output side of the vibrator shaft 10. The second cover 27 has connecting holes 27h1, 27h2 that communicate with the connecting holes 23h1, 23h2 of the second internal gear 23, respectively. The connecting hole 27h1 is a through hole for fastening the second cover 27 between an external member to be driven and the second internal gear 23. The connecting hole 27h2 is a through hole having a seat surface for the connecting member 52, and the inserted connecting member 52 is screwed into the connecting hole 23h2 of the second internal gear 23, whereby the second cover 27 is connected to the second internal gear 23 by itself.

[0022] The input bearing 31 is disposed between the shaft portion 10B of the vibrator shaft 10 and the first cover 26. The first cover 26 supports the vibrator shaft 10 via the input bearing 31 so as to be rotatable. The input bearing 32 is disposed between the shaft portion 10C of the vibrator shaft 10 and the second cover 27. The second cover 27 supports the vibrator shaft 10 via the input bearing 32 so as to be rotatable.

[0023] The main bearing 33 has an inner ring, an outer ring, and rolling elements, and is disposed between the second internal gear 23 and the casing 24. The casing 24 rotatably supports the second internal gear 23 via the main bearing 33. Although a ball bearing is shown as the main bearing 33 in FIG. 1, any type of bearing may be used, such as a roller bearing, a cross roller bearing, an angular ball bearing, a tapered bearing, or the like. The outer ring of the main bearing 33 may be integrally formed with the casing 24.

[0024] [Materials of each component (except gears)] The materials of the members other than the gears are not particularly limited, but in this embodiment, they are configured as follows. The casing 24, the first cover 26, and the second cover 27 are made of a resin material. The resin material may be a simple resin or a resin containing reinforcing fibers, and various resin materials such as PEEK (Poly Ether Ether Ketone) material and POM (Polyacetal, Polyoxymethylene, etc.) may be used. Examples of resin containing reinforcing fibers include composite materials such as CFRP (Carbon Fiber Reinforced Plastics), composite materials of resin and other materials, and baked goods (paper baked goods, cloth baked goods, etc.). By making these members from resin, the cost and weight of the gear device 1 can be reduced.

[0025] The vibrator shaft 10 and the spacer rings 36, 37 are made of a metal material such as steel. Although not particularly limited, more specifically, the vibrator shaft 10 is made of a steel material such as chrome molybdenum steel. The spacer rings 36, 37 are made of a steel material such as high carbon chrome bearing steel.

[0026] [Materials for external and internal gears] The external gear 12 is made of a steel material (metal material) such as nickel-chromium-molybdenum steel. On the other hand, the first internal gear 22 and the second internal gear 23 are made of a carbon fiber reinforced resin material in which carbon fibers are contained as reinforcing fibers in a base resin. For the base resin, various resin materials such as PEEK (Poly Ether Ether Ketone) material and POM (Polyacetal or Polyoxymethylene, etc.) can be used. When the reinforcing fibers contained in the resin material are fibers that are not bound in a cloth-like shape, the resin material can be injection molded or compression molded. When the material contained in the resin material is fibers that are bound in a cloth-like or strip-like shape, the resin material can be compression molded. It is sufficient that at least one of the first internal gear 22 and the second internal gear 23 is made of a carbon fiber reinforced resin material.

[0027] In this embodiment, as described above, the external gear 12 is made of metal, whereas the internal gears (the first internal gear 22 and the second internal gear 23) that mesh with the external gear 12 are made of carbon fiber reinforced resin. Conventionally, it has been common knowledge among those skilled in the art that it is difficult to use carbon fiber reinforced plastic as a gear material as in this embodiment, because the carbon fibers exposed on the tooth surface attack the mating gear, causing early damage to both the plastic gear itself and the mating gear.

[0028] In this regard, the inventors have overturned the above-mentioned common knowledge in the technical field of gears, and discovered that the above-mentioned defects occur when external gears with protruding teeth on the outer periphery mesh with each other (external meshing), and that when external gears and internal gears mesh (internal meshing), early damage can be suppressed even when gears made of carbon fiber reinforced resin are used. This is believed to be because the tooth surface pressure and sliding speed (relative sliding speed between the external gear and the internal gear) are smaller in the case of internal meshing than in the case of external meshing.

[0029] In internal meshing, convex teeth and concave teeth mesh together, so the contact area of ​​the tooth surfaces is increased and the tooth surface pressure is reduced compared to external meshing, in which convex teeth mesh with each other. Furthermore, in internal meshing, the meshing gears rotate in the same direction, so the slip speed is smaller than in external meshing. When the inventors verified various types of gear devices, they obtained good results with internal meshing when the slip speed was approximately 1000 mm / s or less (input rotation speed: approximately 2000 rpm). Note that the input rotation speed value of "2000 rpm" mentioned above does not limit the input rotation speed when used as a product.

[0030] The second internal gear 23 has a fluid solidified portion whose outer surface is formed by solidifying a molten resin material (i.e., a fluid material), and a machined portion whose outer surface is machined. The outer surface means the surface that comes into contact with air when the second internal gear 23 is viewed alone. Machined processing is a concept that includes polishing. Tool marks (tool traces) of a tool are added to the machined portion. On the other hand, the tool marks do not appear in the fluid solidified portion. The machined portion and the fluid solidified portion can be distinguished by the presence or absence of the tool marks. Furthermore, when the fluid solidified portion is formed by injection molding, one of the portions of the fluid solidified portion includes the shape of a gate portion through which the molten resin material passes when filling the mold.

[0031] The cut portion of the second internal gear 23 includes teeth 23g. The method of cutting the teeth 23g is not particularly limited, but includes, for example, tooth forming processing using a gear shaper, a skyping cutter, a hob, etc., and may also be grinding processing using a grindstone. Carbon fibers may be exposed on the tooth surface of the teeth 23g by this cutting processing. Note that carbon fibers may be exposed on the tooth surface without performing cutting processing. While a machined portion can provide high machining accuracy, the additional steps increase costs, and therefore it is preferable to machine only the teeth 23g.

[0032] The fluid solidified portion of the second internal gear 23 includes the portion other than the machined portion. The fluid solidification portion is formed by, for example, injection molding, but may also be formed by compression molding of a fiber-reinforced resin. The outer shape of the fluid solidification portion is formed to conform to the shape of the mold.

[0033] The first internal gear 22, like the second internal gear 23, has a fluid solidified portion whose outer surface is formed by solidifying a molten resin material, and a machined portion whose outer surface is machined. The machined portion of the first internal gear 22 includes teeth 22g. Carbon fibers may be exposed on the tooth surface of the teeth 22g by the machined process. Note that the carbon fibers may be exposed on the tooth surface without the machined process. The fluid solidified portion of the first internal gear 22 includes the portion other than the machined portion.

[0034] [Gear system operation] When the vibration exciter shaft 10 is rotated by a driving source such as a motor, the motion of the vibration exciter 10A is transmitted to the external gear 12. At this time, the external gear 12 is restricted to a shape that conforms to the outer circumferential surface of the vibration exciter 10A, and is bent into an elliptical shape having a major axis portion and a minor axis portion when viewed from the axial direction. Furthermore, the external gear 12 is meshed with the fixed first internal gear 22 at the major axis portion. Therefore, the external gear 12 does not rotate at the same rotation speed as the vibration exciter 10A, and the vibration exciter 10A rotates relatively inside the external gear 12. Then, with this relative rotation, the external gear 12 is bent and deformed so that the major axis position and the minor axis position move in the circumferential direction. The period of this deformation is proportional to the rotation period of the vibration exciter shaft 10.

[0035] When the external gear 12 flexes and deforms, the position of its major axis moves, and the meshing position between the external gear 12 and the first internal gear 22 changes in the rotational direction. For example, if the number of teeth of the external gear 12 is 100 and the number of teeth of the first internal gear 22 is 102, the meshing teeth of the external gear 12 and the first internal gear 22 shift each time the meshing position moves around once, causing the external gear 12 to rotate (spin on its axis). With the above number of teeth, the rotational motion of the vibration exciter shaft 10 is decelerated at a reduction ratio of 100:2 and transmitted to the external gear 12.

[0036] Meanwhile, since the external gear 12 also meshes with the second internal gear 23, the meshing position between the external gear 12 and the second internal gear 23 also changes in the rotational direction due to the rotation of the vibration exciter shaft 10. If the number of teeth of the second internal gear 23 and the number of teeth of the external gear 12 are the same, the external gear 12 and the second internal gear 23 do not rotate relative to each other, and the rotational motion of the external gear 12 is transmitted to the second internal gear 23 at a reduction ratio of 1:1. As a result, the rotational motion of the vibration exciter shaft 10 is decelerated at a reduction ratio of 100:2 and transmitted to the second internal gear 23 and the second cover 27, and this rotational motion is output to the external member to be driven.

[0037] At this time, the internal gears (first internal gear 22, second internal gear 23) made of carbon fiber reinforced resin are in internal mesh with the external gear 12 made of metal. Therefore, if carbon fiber reinforced resin gears were to be externally meshed, the carbon fibers exposed on the tooth surface of the gear could attack the mating gear and cause damage, but in this embodiment, the carbon fiber reinforced resin internal gear is internally meshed, so the tooth surface pressure and sliding speed can be reduced and damage to the gears can be suppressed.

[0038] [Technical effect of the present embodiment] As described above, according to this embodiment, the external gear 12 is made of metal, and the internal gears (first internal gear 22 and second internal gear 23) are made of carbon fiber reinforced resin. That is, the internal gear made of carbon fiber reinforced resin is in internal mesh with the external gear 12 made of metal. This makes it possible to reduce the tooth surface pressure and sliding speed compared to the conventional method in which carbon fiber reinforced plastic gears were externally meshed, thereby suppressing damage to the gears. Therefore, carbon fiber reinforced resin can be suitably used as a gear material, which in turn makes it possible to suitably achieve a reduction in weight, an increase in strength, and a longer life for the gear. In this embodiment, the first internal gear 22 and the second internal gear 23 (intermediate bodies) are formed by injection molding, and then the teeth are formed by cutting, so that it is possible to improve gear accuracy (compared to the case where the teeth are formed only by injection molding) while reducing manufacturing costs. Even if carbon fibers are exposed on the tooth surface by cutting the tooth portion, damage to the gears can be suppressed because the tooth surface pressure and sliding speed are small. In addition, in this embodiment, by adopting a flexible mesh gear device as the gear device, a configuration is realized in which the relative sliding speed between the external gear and the internal gear is 1000 mm / s or less when the input rotation speed is 2000 rpm.

[0039] [Variations] Next, an example in which the present invention is applied to an eccentric oscillating gear device will be described. FIG. 2 is a cross-sectional view showing a gear device 2 according to this modified example, and FIG. 3 is a cross-sectional view taken along line AA in FIG.

[0040] As shown in Figures 2 and 3, the gear device 2 of this modified example is an eccentric oscillating type gear device and includes an input shaft 61, an external gear 62, an internal gear 63, a first carrier 64 and a second carrier 65, a casing 66, main bearings 71, 72, an inner pin 74, and a carrier pin 76. The input shaft 61 has a plurality of (two in this modified example) eccentric portions 61a. The input shaft 61 is supported on the second cover 78 via an input shaft bearing 67 on the non-output side, and is supported on the first carrier 64 via the input shaft bearing 67 on the opposite output side.

[0041] The external gears 62 are provided individually corresponding to the multiple eccentric portions 61a, and are rotatably supported by the corresponding eccentric portions 61a via eccentric bearings 68. The external gear 62 is formed with three carrier pin holes 62a, through which the carrier pins 76 are inserted, and nine inner pin holes 62b, through which the inner pins 74 are inserted, at positions offset from the axis of the external gear 62. Wave-shaped teeth are formed on the outer periphery of the external gear 62. Similarly to the external gear 12 of the above embodiment, the external gear 62 is made of metal.

[0042] The internal gear 63 has internal teeth 63 a formed integrally with the inner periphery of the casing 66 , and the internal teeth 63 a mesh with the teeth of the external gear 62 . The internal gear 63 is made of carbon fiber reinforced resin, similar to the internal gear of the above embodiment. The internal gear 63 may have teeth formed by cutting after injection molding, or the carbon fibers may be exposed on the tooth surface, similar to the above embodiment.

[0043] The first carrier 64 is disposed on a side portion of the external gear 62 on the output side, and the second carrier 65 is disposed on a side portion of the external gear 62 on the opposite side to the output side. The first carrier 64 and the second carrier 65 are rotatably supported on a casing 66 via a first main bearing 71 and a second main bearing 72. The first carrier 64 and the second carrier 65 are connected via a carrier pin 76 and an inner pin 74. The carrier pin 76 and the inner pin 74 axially penetrate the multiple external gears 62 at positions radially offset from the axis of the external gears 62.

[0044] The casing 66 has an internal gear 63 on its inner periphery. A first cover 77 that covers the output side of the casing 66, and a second cover 78 that covers the opposite output side are fixed to the casing 66. The main bearing 71 is disposed between the first carrier 64 and the casing 66 , and the main bearing 72 is disposed between the second carrier 65 and the casing 66 .

[0045] The inner pin 74 is inserted into the inner pin hole 62b with a gap therebetween, and one end of the inner pin 74 is fitted into the first carrier 64, and the other end is fitted into the second carrier 65, respectively. The carrier pin 76 is inserted into the carrier pin hole 62a with a gap therebetween, and one end of the carrier pin 76 is fitted into the first carrier 64 and the other end is fitted into the second carrier 65. The carrier pin 76 is surrounded by a tubular spacer 79. The carrier pin 76 functions as a connecting member that contributes only to the connection between the first carrier 64 and the second carrier 65. In addition, a portion of the carrier pin 76 and the inner pin 74 may be formed integrally with the carriers 64 and 65 .

[0046] With this configuration, in the gear device 2, when rotational power is input to the input shaft 61, the eccentric portion 61a of the input shaft 61 rotates around the rotation center line, and the eccentric portion 61a causes the external gear 62 to oscillate. At this time, the external gear 62 oscillates so that its axis rotates around the rotation center line of the input shaft 61. When the external gear 62 oscillates, the meshing positions of the external gear 62 and the internal gear 63 are sequentially shifted. As a result, each time the input shaft 61 rotates once, one of the external gear 62 and the internal gear 63 rotates on its own axis by an amount corresponding to the difference in the number of teeth between the external gear 62 and the internal gear 63. In this modified example, the external gear 62 rotates on its own axis, and reduced rotation is output from the first carrier 64.

[0047] In this modified example, the same effects as those of the above embodiment can be obtained. That is, because the carbon fiber reinforced resin internal gear is in inscribed mesh with the metal external gear 12, the tooth surface pressure and sliding speed can be reduced compared to the conventional method, and damage to the gear can be suppressed. Therefore, carbon fiber reinforced resin can be suitably applied to the gear material. As a result, the gear can be made lighter, stronger, and have a longer life. In the gear device 2 of this modified example, good results were also obtained when the slip speed (relative slip speed between the external gear 62 and the internal gear 63) was approximately 1000 mm / s or less (input rotation speed of the input shaft 61: approximately 2000 rpm). Note that the above-mentioned input rotation speed value of "2000 rpm" does not limit the input rotation speed when used as a product. In other words, in this modified example, by adopting an eccentric oscillating gear device as the gear device, a configuration is realized in which the relative slip speed between the external gear and the internal gear is 1000 mm / s or less when the input rotation speed is 2000 rpm.

[0048] [others] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and its modifications. For example, in the above embodiment and its modified example, the external gear is made of metal and the internal gear is made of carbon fiber reinforced resin. However, (at least one of) the internal gears may be made of metal and the external gear may be made of carbon fiber reinforced resin.

[0049] In the above embodiment and its modified example, the gear device according to the present invention is applied to a cylindrical flexible mesh gear device and a center crank eccentric oscillating gear device. However, the gear device according to the present invention is widely applicable to gears that mesh internally, and can be applied to flexible mesh gear devices other than cylindrical types (for example, so-called cup type or top hat type) and eccentric oscillating gear devices other than center crank types (for example, distribution type), and can also be suitably applied to other types of gear devices such as simple planetary gear devices.

[0050] In addition, the details shown in the above embodiment can be modified as appropriate without departing from the spirit of the invention. [Explanation of symbols]

[0051] 1, 2 Gear unit 10 Vibration axis 10A vibrator 12 External gear 22 First internal gear 22g Teeth 23 Second internal gear 23g Teeth 61 Input shaft 62 External gear 63 Internal gear 63a Inner teeth 64 First Carrier 65 Second Carrier 74 Inner Pin 76 Carrier pin O1 Rotational Axis

Claims

1. A gear device including an external gear and an internal gear meshing with the external gear, The external gear is made of metal, The internal gear is made of carbon fiber reinforced resin. Gear mechanism.

2. The internal gear has carbon fibers exposed on the tooth surface.

2. The gear arrangement of claim 1.

3. The internal gear has a fluid solidified portion formed by solidifying a carbon fiber reinforced resin and a machined portion machined by a cutting process, The cutting portion includes teeth.

3. The gear arrangement of claim 2.

4. An input shaft is provided. When the input rotation speed input to the input shaft is 2000 rpm, the relative sliding speed between the external gear and the internal gear is 1000 mm / s or less. A gear arrangement according to any one of claims 1 to 3.

5. The gear device is a flexible mesh gear device or an eccentric oscillating gear device, A gear arrangement according to any one of claims 1 to 4.

6. A gear device including an external gear and an internal gear meshing with the external gear, The internal gear is made of metal, The external gear is made of carbon fiber reinforced resin. Gear mechanism.

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