Reduction gear

Abstract

To provide a cycloid reduction gear having excellent quietness and abrasion resistance of a gear without having a complex seal structure and without generating a noise in use even without a maintenance by an oil supply.SOLUTION: A reduction gear 1 includes: an input shaft 11 which is synchronously connected to a rotation shaft 2 of a drive source, and has an input rotation core O2 eccentric to a drive rotation core O1 of the drive source; an external teeth gear 12 which is provided in a relatively rotational manner with respect to the input shaft 11 about an input rotation core O2 as a center, and has five teeth 121 with an epitrochoid parallel curve on an outer periphery; an internal teeth gear 13 in which six resin outer rollers 131 corresponding to the epitrochoid parallel curve according to the external teeth gear 12 are rotationally supported; an output shaft 14 which is rotational about the drive rotation core O1; and an inner pin 15 which is fixed to the external teeth gear 12, and is slidable along an inner periphery of an inner pin hole 143 formed in an axial direction of the output shaft 14.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a reducer that reduces the speed of rotation input from a drive source. [Background technology]

[0002] Generally, in industrial robots, production machinery, drive control units for vehicles, etc., reducers are widely used for the purpose of adjusting the rotation speed of the motor that serves as the drive source and the rotation speed required by the driven source, or for amplifying and outputting the torque of the drive source to the driven source.

[0003] One type of reducer known is an eccentric oscillating reducer, which is composed of an input shaft that rotates eccentrically relative to the axis of the rotation shaft of the drive source, an external gear that is connected to the input shaft via a bearing and is arranged to be able to oscillate and rotate, an internal gear that internally meshes with the external gear, and an output shaft that outputs the rotational motion of the external gear.

[0004] Also known as a type of eccentric oscillating reducer is a cycloid reducer that uses an external gear with teeth that form an epitrochoid parallel curve on the outer periphery, and is disclosed, for example, in Patent Document 1. Compared to reducers that use involute gears, cycloid reducers have a greater number of simultaneously meshing gear teeth, and are therefore characterized by excellent quietness. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-44400 A [Patent Document 2] Japanese Patent Application Publication No. 7-243486 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-191447 Summary of the Invention [Problem to be solved by the invention]

[0006] Such cycloidal reducers have traditionally been used in fields that handle relatively large amounts of power, and have typically required lubrication such as grease to be applied to the meshing areas between the external gear and the internal gear, and maintenance has been required during use.

[0007] However, in recent years, there has been a demand for applying such cycloidal reducers to a wider range of applications, and in order to enable use without limiting applications, there is a demand for a cycloidal reducer that does not require maintenance such as oil leakage prevention measures or lubrication.

[0008] In response to such demands, Patent Document 2 discloses a cycloidal reducer that uses resin external and internal gears. However, with this structure, the sliding properties between the internal and external gears are insufficient, and therefore, in an environment where oil is not added, there is a possibility that abnormal noise will be generated during use and the internal gear will wear unevenly.

[0009] On the other hand, Patent Document 3 discloses a cycloidal reducer in which the bearing retainer is made of resin, but because the external gear and internal gear are made of metal, measures against abnormal noise are insufficient in an environment where oil is not added.

[0010] Therefore, an object of the present invention is to provide a cycloidal reducer that does not have a complex sealing structure, does not require maintenance by lubrication, does not generate abnormal noise during use, is quiet, and has excellent gear wear resistance. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention provides an input shaft that is synchronously connected to a rotation shaft of a drive source and has an input rotation shaft center that is eccentric with respect to a drive rotation shaft center of the drive source; an external gear arranged to be rotatable relative to the input shaft about the input rotation axis, the external gear having teeth on an outer periphery that form an epitrochoid parallel curve; an internal gear in which a plurality of resin outer rollers corresponding to the epitrochoid parallel curve of the external gear are rotatably supported; an output shaft rotatable about the drive rotation axis; an inner pin fixed to one of the internal gear and the output shaft and slidable along an inner periphery of an inner pin hole formed in the other of the internal gear and the output shaft in the output shaft direction; The reducer is characterized by comprising:

[0012] According to the above-described speed reducer, when the rotation shaft of the drive source rotates, the input shaft, which has an input rotation axis eccentric with respect to the drive rotation axis of the drive source, also rotates synchronously. The external gear, which is arranged to be rotatable relative to the input shaft, revolves around the drive rotation axis in the rotation direction of the drive source and sequentially abuts against the multiple outer rollers of the internal gear. At this time, the external gear rotates around the input rotation axis in the direction opposite to the rotation direction of the input shaft, corresponding to the epitrochoid parallel curve. As the external gear rotates, power is transmitted to the output shaft via the inner pin, so that the output shaft rotates around the drive rotation axis in the direction opposite to the rotation direction of the drive source at a reduced rotation speed. During the above operation, the outer roller of the internal gear meshes with the teeth of the external gear, rotating in the direction of the drive source at the same rotational speed as the rotation of the external gear. At this time, because the outer roller of the internal gear is made of a resin that is self-lubricating (has a small coefficient of friction), there is sliding between the teeth of the external gear and the outer roller of the internal gear, and even without lubrication, no abnormal noise is generated during use, resulting in a configuration that is quiet and has excellent wear resistance.

[0013] Further, in the above-mentioned reducer, the present invention is characterized in that a first bearing made of resin is provided between the input shaft and the external gear, A second bearing made of resin is provided on the inner periphery of the inner pin hole, The output shaft may be disposed so as to be rotatable relative to the input shaft, and a third bearing made of resin may be provided between the input shaft and the output shaft.

[0014] According to the above configuration, in addition to the outer roller of the internal gear, the first bearing provided between the input shaft and the external gear, the second bearing provided on the inner circumference of the inner pin hole, and the third bearing provided between the input shaft and the output shaft are also made of a self-lubricating resin, so all of the connecting parts involved in the power transmission of the reducer have sliding properties, and even without lubrication, no abnormal noise is generated during use, resulting in a configuration that is quiet and has excellent wear resistance.

[0015] Furthermore, in the present invention, in the reducer, the resin material forming the outer rollers of the internal gear may have a limit PV value of 2 MPa·m / s or more.

[0016] According to the above configuration, the sliding properties between the outer roller of the internal gear and the external gear can be improved, and as a result, even when the outer roller is in continuous contact with the internal gear without lubrication, quietness and wear resistance of the gear can be improved. [Effects of the Invention]

[0017] It is possible to provide a cycloid reducer that does not have a complicated seal structure, does not require maintenance by lubrication, does not generate abnormal noise during use, is quiet, and has excellent wear resistance of gears. [Brief explanation of the drawings]

[0018] [Figure 1] 2 is a cross-sectional view including a drive rotation axis and an input rotation axis of the reducer of the present embodiment. FIG. [Figure 2] 2 is a cross-sectional view of the reducer taken along line AA in FIG. 1. [Figure 3] FIG. 2 is an exploded view of the reducer of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] (Reducer 1) As shown in Figures 1 to 3, a reducer 1 according to an embodiment of the present invention is an eccentric oscillating cycloid reducer, comprising: an input shaft 11 synchronously connected to a rotating shaft 2 of a drive source (not shown), such as a motor, and having an input rotational axis O2 eccentric with respect to a drive rotational axis O1 of the drive source; an external gear 12 arranged rotatably relative to the input shaft 11 around the input rotational axis O2 and having five teeth 121 with an epitrochoid parallel curve on its outer periphery; an internal gear 13 having six resin outer rollers 131 corresponding to the epitrochoid parallel curve of the external gear 12 rotatably supported in a housing 132; an output shaft 14 rotatable around the drive rotational axis O1; and three inner pins 15 fixed to the external gear 12 and slidable along the inner periphery of three inner pin holes 143 formed in the axial direction of the output shaft 14 (output axis direction).

[0020] (Input shaft 11) The input shaft 11 is connected to the rotating shaft 2 of a drive source (not shown) such as a motor, and has an input shaft body 111 that is concentric with the drive rotation axis O1 of the drive source, and an eccentric body 112 that has an input rotation axis O2 that is eccentric with respect to the drive rotation axis O1, with the eccentric body 112 arranged on the outer periphery of the input shaft body 111, forming an integrated configuration.

[0021] A key groove (not shown) is formed in the input shaft body 111 of the input shaft 11, and by fitting with a key (not shown) of the rotating shaft 2 of the drive source, the input shaft 11 and the rotating shaft 2 of the drive source are connected so as not to rotate relative to each other. As a result, the input shaft 11 is connected to the rotating shaft 2 of the drive source and rotates in synchronization with the rotation of the rotating shaft 2 of the drive source.

[0022] Furthermore, since the input shaft 111 is integral with the eccentric body 112, the input rotation axis O2 of the input shaft 11 is eccentric (misaligned) with respect to the drive rotation axis O1.

[0023] A first bearing 16 made of resin is attached between the outer periphery of the eccentric body 112 of the input shaft 11 and the inner periphery of the external gear 12, and transmits the rotational motion of the input shaft 11 to the external gear 12. Furthermore, a third bearing 18 is attached to the input shaft 11 at the portion where the outer periphery of the input shaft body 111 of the input shaft 11 contacts the inner periphery of the output shaft 14, ensuring sliding ability relative to the output shaft 14.

[0024] (External gear 12) The external gear 12 is a trochoid gear having, on its outer periphery, five teeth 121 in the shape of an epitrochoid parallel curve that corresponds to the outer diameter of the outer roller 131 of the internal gear 13. The external gear 12 is disposed via a first bearing 16 so as to be rotatable relative to the input shaft 11 about the input rotation axis O2. Because the input rotation axis O2 of the external gear 12 is eccentric with respect to the drive rotation axis O1, the external gear 12 oscillates (rotates while revolving) with the rotation of the input shaft 11. The operation of the eccentric oscillating reducer in which the external gear 12 transmits power while oscillating will be described later.

[0025] In addition, the external gear 12 has three holes formed at equal intervals on a circumference centered on the input rotation axis O2, and an inner pin 15 is press-fitted into each of these three holes to form an integral unit. The material of the external gear 12 is not particularly limited, but may be made of steel, for example.

[0026] (Internal gear 13) The internal gear 13 includes a housing 132 formed in an arc shape centered on the drive rotation axis O1, and six outer rollers 131 arranged at equal intervals on the circumference of the housing 132 centered on the drive rotation axis O1.

[0027] (Outer roller 131) The outer roller 131 has an outer diameter corresponding to the epitrochoid parallel curve of the external gear 12 , and therefore meshes with the teeth 121 of the external gear 12 . The number of outer rollers 131 (number of teeth) of the internal gear 13 is set to N+1, where N is the number of teeth 121 of the external gear 12.

[0028] The outer roller 131 is rotatably supported (held) by the housing 132, and is in rolling contact with the external gear 12. This reduces wear compared to sliding contact.

[0029] The outer roller 131 is made of a resin with a low coefficient of friction and self-lubricating properties. Examples of resins that can be used include thermoplastic resins such as polyamide, polyacetal, polytetrafluoroethylene, polyphenylene sulfide, and ultra-high molecular weight polyethylene, as well as thermosetting resins such as phenol. Furthermore, these resins, which are the main components, may be blended with lubricants such as molybdenum disulfide, tungsten disulfide, graphite, boron nitride, tetrafluoroethylene fine powder, oil, and wax. In this way, since the outer roller 131 is made of a resin having self-lubricating properties, the contact portion due to meshing with the teeth 121 of the external gear 12 slides well and is quiet even without oiling.

[0030] (Limit PV value of outer roller 131) The resin material forming the outer roller 131 preferably has a limit PV value of 2 MPa·m / s or more.

[0031] In this embodiment, the PV value is the product of the surface-to-surface contact pressure (P) and the velocity (V), and the limiting PV value is the PV value calculated from the surface pressure (P) at which sudden wear or thermal softening (abnormal damage) occurs on the surface of the resin material (test piece) in contact with the mating material in a sliding wear test (also known as a thrust friction wear test or a ring-on-disc wear test) in accordance with JIS K7218 (1986) Method A. The test piece is a hollow cylindrical test piece with an inner diameter of 20 mm, an outer diameter of 25.6 mm, and a height of 15 mm, which is brought into contact with the end face of a mating material made of S45C carbon steel under dry (unlubricated) lubrication conditions at an ambient temperature of 23°C and a relative humidity of 50%. The mating material is caused to slide (rotate) at a constant speed (V) with an initial surface pressure (P) applied, and the surface pressure (P) is gradually increased from that state during a pressurization step. Specific measurement conditions include an ambient temperature of 23°C, a relative humidity of 50%, a speed (circumferential speed V) of 30 m / min, an initial surface pressure (P) of 1.0 MPa, and a pressure step of 1.0 MPa / 10 min., at which the limiting PV value can be measured.

[0032] As mentioned above, the limiting PV value generally refers to the PV value (product of inter-surface contact pressure (P) and velocity (V)) (limiting load value) at which sudden wear or thermal softening (abnormal damage) occurs on the surface of a resin material that comes into contact with a mating material used in sliding parts (sliding bearings). Therefore, the larger the limiting PV value, the better the friction and wear characteristics and the higher the load resistance, while the smaller the limiting PV value, the more limited the application to low loads. Therefore, if the limit PV value of the resin material forming the outer roller 131 is 2 MPa·m / s or more, the sliding properties between the outer roller 131 and the external gear 12 can be improved compared to when the limit PV value is below 2 MPa·m / s, and therefore even if the outer roller 131 is in continuous contact with the external gear 12 without lubrication, quietness and the wear resistance of the external gear 12 can be improved.

[0033] (Housing 132) The housing 132 has six outer roller holes 132A formed therein, which are arranged at equal intervals around the circumference of the housing 132 centered on the drive rotation axis O1, and each outer roller 131 is rotatably fitted into each outer roller hole 132A (see Figures 1 and 3).

[0034] The housing 132 is a component that constitutes the internal gear 13, and also serves as a cover to prevent foreign matter from entering the inside of the reducer 1 from the input shaft 11 side (the right side in FIG. 1). In addition, a bearing 191 is provided between the input shaft 11 and the housing 132 to prevent the housing 132 from rotating relative to the rotation of the input shaft 11.

[0035] (Inner pin 15) The inner pins 15 have a cylindrical shape that is smaller than the inner diameter of the inner pin hole 143 formed in the output shaft 14, and are press-fitted into holes formed in the external gear 12 to be integrated. Therefore, the three inner pins 15 rotate synchronously with the rotation of the external gear 12 around the input rotation axis O2. The rotation of the three inner pins 15 is transmitted to the output shaft 14 by sliding and rotating along the inner periphery of a second bearing 17 made of resin that is provided on the inner periphery of the inner pin hole 143 formed in the output shaft 14. The material of the inner pin 15 is not particularly limited, but may be made of steel, for example.

[0036] (output shaft 14) The output shaft 14 is formed with a shaft portion 141 and a flange portion 142, and three inner pin holes 143, each larger than the outer diameter of the inner pin 15, are formed in the flange portion 142 on a circumference centered on the drive rotation axis O1. A second bearing 17 made of resin is fitted into the inner periphery of the inner pin hole 143, and each inner pin 15 slides along the inner periphery of the second bearing 17. Furthermore, a third bearing 18 is attached to the output shaft 14 at a portion where the outer periphery of the input shaft body 111 of the input shaft 11 contacts the inner periphery of the flange portion 142 of the output shaft 14, and the output shaft 14 has sliding properties with respect to the input shaft 11. In other words, the output shaft 14 is disposed so as to be rotatable relative to the input shaft 11.

[0037] The output shaft 14 has the same rotation axis as the drive rotation axis O1 of the drive source, and rotates with the rotation of the inner pin 15. At this time, the rotation speed of the output shaft 14 is 1 / N of the rotation speed of the input shaft 11, and the rotation that is output is reduced by the reduction ratio N (= rotation speed of the input shaft / rotation speed of the output shaft). That is, the rotational speeds of the input shaft 11 and the output shaft 14 are reduced by the number N of teeth 121 of the external gear 12, and the reduction ratio becomes N.

[0038] (First bearing 16, second bearing 17, third bearing 18) In the reducer 1 of this embodiment, as described above, a first bearing 16 made of resin is provided between the input shaft 11 and the external gear 12, a second bearing 17 made of resin is provided on the inner circumference of the inner pin hole 143 of the output shaft 14, and a third bearing 18 made of resin is provided between the input shaft 11 and the output shaft 14.

[0039] The first bearing 16, the second bearing 17, and the third bearing 18 are preferably made of a material that has a low coefficient of friction and is self-lubricating, similar to the outer roller 131 of the internal gear 13.

[0040] (Cover 193) The cover 193 serves to prevent foreign matter from entering the inside of the reducer 1 from the output shaft 14 side (left side in FIG. 1). In addition, a bearing 192 is provided between the output shaft 14 and the cover 193 so that the cover 193 does not rotate relative to the rotation of the output shaft 14.

[0041] (Thrust washer 194·195) Resin thrust washers 194, 195 are disposed between the input shaft 11 and the output shaft 14, and between the external gear 12 and the housing 132, respectively, to reduce frictional resistance.

[0042] (Assembly of reducer 1) The reducer 1 in this embodiment can be assembled in the following procedure. (1) The inner pin 15 is press-fitted into a hole formed in the external gear 12 to be integrated. Furthermore, the input shaft 11 and the first bearing 16, the input shaft 11 and the third bearing 18, and the output shaft 14 and the second bearing 17 are integrated together.

[0043] (2) Each outer roller 131 is inserted into each outer roller hole 132A of the housing 132, and the housing 132, outer roller 131, thrust washer 195, bearing 191, input shaft 11, first bearing 16, external gear 12, inner pin 15, second bearing 17, third bearing 18, thrust washer 194, output shaft 14, bearing 192, and cover 193 are integrated together as shown in Fig. 3. At this time, each outer roller 131 is simply inserted into the outer roller hole 132A of the housing 132, so it can come into sliding contact with the housing 132 and into rolling contact with the external gear 12.

[0044] (3) The fastening screws 199 are fastened to the screw holes provided in the cover 193 and the housing 132, respectively, and the assembly of the reducer 1 is completed.

[0045] (Operation of reducer 1) In the reducer 1 of this embodiment, when the rotary shaft 2 of the drive source (not shown) rotates, the connected input shaft 11 rotates together with the eccentric body 112 that is integral with it. When the input shaft 11 integrated with the eccentric body 112 rotates, for example, clockwise on Figure 2, the rotational motion is transmitted to the external gear 12 via the first bearing 16, and the external gear 12 also rotates (revolves) clockwise around the drive rotation axis O1.

[0046] As the external gear 12 revolves clockwise around the drive rotation axis O1, it sequentially comes into contact with the outer rollers 131 of the internal gear 13 provided on the outer periphery. At this time, the number of outer rollers 131 of the internal gear 13 (6 teeth: N+1) is one more than the number of teeth 121 of the external gear 12 (5 teeth: N), so there is a circumferential phase shift equivalent to the difference in the number of teeth of 1, and the external gear 12 rotates (spins) counterclockwise in FIG. 2 around the input rotation axis O2. As a result, the external gear 12 rotates (oscillates) in the direction opposite to the revolution at a rotation speed reduced by a reduction ratio of 5 (N). At this time, the outer roller 131 of the internal gear 13 meshes with the external gear 12, and rotates (spins) clockwise at the same rotation speed as the rotation of the external gear 12.

[0047] As the external gear 12 oscillates and rotates, the inner pin 15, which is integral with the external gear 12, also oscillates and rotates. The oscillating rotation of the inner pin 15 is transmitted to the output shaft 14 via the second bearing 17, so that the output shaft 14 rotates counterclockwise around the drive rotation axis O1. As a result, the output shaft 14 rotates in the direction opposite to the rotation direction of the input shaft 11 at a rotation speed reduced by the reduction ratio 5(N).

[0048] According to the above-mentioned speed reducer 1, during the above-mentioned operation process, the outer roller 131 of the internal gear 13 meshes with the teeth 121 of the external gear 12, and rotates in the rotational direction of the rotary shaft 2 of the drive source at the same rotational speed as the rotation of the external gear 12. At this time, since the outer roller 131 of the internal gear 13 is made of a resin that has self-lubricating properties (small coefficient of friction), there is sliding ability between the teeth 121 of the external gear 12 and the outer roller 131 of the internal gear 13, and no abnormal noise occurs during use even without lubrication, making it possible to achieve a configuration that is quiet and has excellent wear resistance.

[0049] Furthermore, in the above-mentioned reducer 1, in addition to the outer roller 131 of the internal gear 13, the first bearing 16 provided between the input shaft 11 and the external gear 12, the second bearing 17 provided on the inner circumference of the inner pin hole 143, and the third bearing 18 provided between the input shaft 11 and the output shaft 14 are also made of a self-lubricating resin, so all of the connecting parts involved in the power transmission of the reducer 1 have sliding properties, and even without lubrication, no abnormal noise is generated during use, resulting in a configuration that is quiet and has excellent wear resistance.

[0050] Furthermore, as shown in Table 1 below, the cycloidal reducer of Patent Document 2 uses internal and external gears made of resin for the purpose of reducing weight and cost, but the contact between the external and internal gears is sliding contact, and without oiling, quietness and wear resistance are poor. In the cycloidal reducer of Patent Document 3, a self-lubricating resin material is used for the bearing cage in order to improve quietness, but the meshing portion between the internal gear and external gear does not have self-lubricating properties, so oiling is still required, resulting in poor maintainability. In contrast, the reducer 1 according to the present invention uses a resin material for the power transmission members, eliminating the need for lubrication and providing excellent maintainability. In other words, it is possible to obtain a reducer 1 that is quiet and has excellent gear wear resistance, based on a configuration that does not require lubrication.

[0051] (Comparison table) [Table 1]

[0052] (Other embodiments) In the reducer 1 of the above embodiment, the inner pin 15 is press-fitted into a hole formed in the external gear 12 to be integrated, and is connected to the output shaft 14 via the second bearing 17, but the inner pin 15 may also be integrated with the output shaft 14. In this case, a plurality of inner pin holes larger than the outer diameter of the inner pins 15 are formed on the circumference of the external gear 12, centered on the input rotation axis O2, and a fourth bearing made of resin (not shown) is fitted into the inner periphery of each inner pin hole. Each inner pin 15 slides along the inner periphery of the corresponding fourth bearing. In this case as well, the connecting portion between the external gear 12 and the output shaft 14 has excellent sliding properties, and therefore is quiet even without lubrication. In this case, the operation of the reducer is the same as in the above embodiment, and the output shaft 14 rotates in the direction opposite to the rotation direction of the input shaft 11 at a rotation speed reduced by the reduction ratio N. [Example]

[0053] In the reducer of the present invention, no abnormal noise is generated during use without the need for maintenance by lubrication, and uneven wear of the internal gear due to use is suppressed. Therefore, in this example, reducers according to Examples 1 and 2 and a comparative example (hereinafter referred to as test specimens) were fabricated and subjected to durability tests for comparative verification. The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0054] [Reducer] The specimens used for evaluation (reducers in Examples 1-2 and Comparative Example) had the same configuration except for the material of the outer roller of the internal gear, as described below (the basic configuration was the same as in the above embodiment, with an external gear having an epitrochoid parallel curve tooth profile on the outer diameter, and an internal gear that internally meshes with this external gear through rolling contact). As shown in FIG. 2, the number of teeth N of the external gear is 5, and the number of outer rollers (number of teeth) of the internal gear is 6 (that is, the reduction ratio is 5).

[0055] [Reducer dimensions] External gear: Number of teeth 5, base circle diameter φ60 mm, rolling circle diameter φ12 mm Internal gear: 6 teeth, pitch circle diameter φ72 mm, outer roller diameter φ15 mm Eccentricity: 3mm Reduction ratio: 5

[0056] [Materials used] Example 1 External gear: Carbon steel (S45C) (JFE Steel Corporation) Outer roller: Polyacetal resin (Mitsuboshi Belting Co., Ltd.'s "Bestal G", limit PV value 1.3 MPa·m / s) Housing: Pre-hardened steel (NAK55) (manufactured by Daido Steel Co., Ltd.) 1st to 3rd bearings: Polyacetal resin ("Bestal G" manufactured by Mitsuboshi Belting Co., Ltd.) (The first to third bearings in Example 1 were sliding bearings.)

[0057] Example 2 External gear: Carbon steel (S45C) (JFE Steel Corporation) Outer roller: Polyamide resin with lubricant (Mitsuboshi Belting "Cast Nylon CL", limit PV value 3.25 MPa m / s) Housing: Pre-hardened steel (NAK55) (manufactured by Daido Steel Co., Ltd.) 1st to 3rd bearings: Polyacetal resin ("Bestal G" manufactured by Mitsuboshi Belting Co., Ltd.) (The first to third bearings in Example 2 were sliding bearings.)

[0058] (Comparative Example) External gear: Carbon steel (S45C) (JFE Steel Corporation) Outer roller: Carbon steel (S45C) (JFE Steel Corporation) Housing: Pre-hardened steel (NAK55) (manufactured by Daido Steel Co., Ltd.) First bearing: A cylindrical roller bearing made of chrome molybdenum steel (SUJ2) was used. Second and third bearings: Polyacetal resin ("Bestal G" manufactured by Mitsuboshi Belting Co., Ltd.) (The second and third bearings of the comparative example were sliding bearings.)

[0059] [Manufacturing of reducers] The outer rollers and first to third bearings of Examples 1 and 2 were each manufactured by injection molding using the materials described above. The external gear and housing were each manufactured by cutting using the materials described above. The external gear, outer roller, and housing of the comparative example were each manufactured by cutting using the materials described above.

[0060] [Reducer assembly] The reducers according to Examples 1 and 2 and the comparative example were assembled according to the procedure described in the above embodiment.

[0061] [Reducer evaluation: items, methods, and standards] In order to determine whether a reducer capable of solving the problem of the present application was obtained, durability tests were conducted on each test specimen (Examples 1-2 and Comparative Example) to verify quietness (whether or not abnormal noise was generated) and wear resistance of the outer roller (whether or not abnormal wear was present).

[0062] [Durability test] (Test Method) In order to assess quietness (whether or not abnormal noise occurs) and the wear resistance of the outer roller (whether or not abnormal wear occurs), a testing machine (not shown) that imitates a servo motor on the input shaft and an electric bicycle wheel drive unit on the output shaft was attached to each test specimen, and the testing machine was operated under the following conditions without performing maintenance such as lubrication.

[0063] (Test conditions) Motor capacity: 0.1kW Input shaft speed: 1000 rpm Output shaft speed: 200 rpm Reduction ratio: 5 Durability test operating time: 5000 hours

[0064] [Quietness] (evaluation) To evaluate quietness, a durability test (5,000 hours of operation) was conducted on the reducer of each test specimen without oiling, and it was determined whether any abnormal noise was observed during operation after the durability test. Specifically, after the durability test under the above conditions, each test specimen was operated again under the same conditions, and 10 evaluators without hearing impairments, positioned 2 m away from the input shaft side of the reducer, judged whether they were able to hear any abnormal noises.

[0065] (Judgment criteria) If none of the evaluators could hear any abnormal noise, the noise was deemed to be completely absent and the reducer's quietness was rated as the best, giving it an A rating. If only one of the evaluators was able to hear the abnormal noise, the noise was judged to be slight and the quietness of the reducer was at an acceptable level, and the rating was given as b. If two or more of the evaluators were able to hear the abnormal noise, the occurrence of the abnormal noise was acknowledged, the quietness of the reducer was rated as unacceptable, and a rating of C was given. From the perspective of suitability for practical use in this application (quietness of the reducer), reducers with a rating of b or higher were considered to be passable.

[0066] [Outer roller wear resistance] (evaluation) In evaluating the wear resistance of the outer roller, the condition of the outer roller of the reducer for each test specimen after the durability test was observed from the outside with a magnifying glass and visually to determine whether or not wear particles were generated.

[0067] (Judgment criteria) If no wear particles were found on the outer roller after the durability test, both by observation with a magnifying glass and by visual inspection, it was determined that there was no uneven wear on the internal gear and that the outer roller had the best wear resistance, and was given an A rating. If no wear powder was found on the outer roller after the durability test by visual inspection, but wear powder was found when observed with a magnifying glass, it was determined that there was only slight uneven wear on the internal gear and the wear resistance of the outer roller was at an acceptable level, and it was given a rating of B. If wear particles were found on the outer roller after the durability test by visual observation, uneven wear of the internal gear was observed, and the wear resistance of the outer roller was evaluated as being at an unacceptable level, giving it a rating of C. From the perspective of suitability for practical use in this application (wear resistance of the outer roller), reducers with a rating of b or higher were deemed to be passable.

[0068] [Overall Judgment] The criteria for the overall assessment (ranking) of a reducer that can solve this problem were determined as follows, based on the results of the assessment of the two evaluation items mentioned above (quietness, wear resistance of the outer roller), and a rank of B or higher was considered to be a pass. If all of the above test items were rated as "a," the product was rated as "Rank A." If there were no C ratings in any of the above test items, but at least one B rating, the product was rated as Rank B. If any of the above test items received a C rating, the product was rated as C. The verification results are shown in Table 2.

[0069] [Verification results and considerations] [Table 2]

[0070] (Examples 1 to 2 and Comparative Examples) The comparative example is an example in which a steel material without self-lubrication was used for the outer roller and first bearing of the internal gear. In the comparative example, when maintenance by lubrication was not performed, the grease ran out, causing abnormalities in sliding performance, and after the durability test, abnormal noise was observed and the generation of wear powder that was visible to the naked eye was observed on the outer roller. As a result, the evaluations of quietness and the wear resistance of the outer roller both received a C rating (fail), and the overall evaluation was a C rank. Example 1 is an example in which a self-lubricating resin material (polyacetal resin) is used for the outer roller of the internal gear and the first bearing. In Example 1, the sliding properties of the power transmission members of the reducer were excellent without maintenance by lubrication, and therefore the generation of abnormal noise was reduced even after the durability test. Furthermore, the generation of wear powder from the outer roller was also improved, so the evaluations of quietness and the wear resistance of the outer roller were both rated B, and the overall evaluation was ranked B. A comparison between the comparative example and Example 1 confirms that using a self-lubricating resin material for the outer roller of the internal gear can improve the quietness of the reducer and the wear resistance of the gears without maintenance by lubrication. In Example 2, the resin material of the outer roller of the internal gear in Example 1 was changed from polyacetal resin (limit PV value 1.3 MPa m / s) to polyamide resin (limit PV value 3.25 MPa m / s) blended with a lubricant. In Example 2, the sliding properties of the outer roller were further improved compared to Example 1, resulting in no abnormal noise after the durability test and no visible wear powder on the outer roller. As a result, both the quietness and the wear resistance of the outer roller were rated as "A," resulting in an overall rating of "A." Comparing Example 1 and Example 2, from the perspective of achieving even better quietness and outer roller wear resistance, it can be said that a limit PV value of 2 MPa m / s or more is preferable for the resin material used for the outer roller.

[0071] (Effects obtained) From Table 2, it can be seen that the reducers of Examples 1 and 2 address the issues, and by using a self-lubricating resin material for the outer roller of the internal gear and the first bearing, the sliding properties of the outer roller are excellent even without maintenance by lubrication, and it is possible to provide a cycloid reducer that does not generate abnormal noise during use, is quiet, and has excellent gear wear resistance. Furthermore, by setting the limit PV value of the resin material used for the outer roller to 2 MPa·m / s or more, the sliding properties of the outer roller are further improved, and it appears possible to provide a cycloid reducer that is quieter and has better gear wear resistance. [Explanation of symbols]

[0072] 1 Reducer 11 Input shaft 111 Input shaft body 112 Eccentric body 12 External gear 121 teeth 13 Internal gear 131 outer roller 132 Housing 14 Output shaft 141 Shaft 142 flange 143 Inner pin hole 15 Inner pin 16 First bearing 17 Second bearing 18 Third bearing 2 rotation axes O1 drive rotation axis O2 input rotation axis

Claims

1. an input shaft synchronously connected to the rotation shaft of the drive source and having an input rotation shaft center eccentric with respect to the drive rotation shaft center of the drive source; an external gear arranged to be rotatable relative to the input shaft about the input rotation axis, the external gear having teeth on an outer periphery that form an epitrochoid parallel curve; an internal gear in which a plurality of resin outer rollers corresponding to the epitrochoid parallel curve of the external gear are rotatably supported; an output shaft rotatable about the drive rotation axis; an inner pin fixed to one of the internal gear and the output shaft and slidable along an inner periphery of an inner pin hole formed in the other of the internal gear and the output shaft in the output shaft direction; A reducer comprising:

2. a first bearing made of resin is provided between the input shaft and the external gear, a second bearing made of resin is provided on the inner periphery of the inner pin hole, 2. The reducer according to claim 1, wherein the output shaft is arranged to be rotatable relative to the input shaft, and a third bearing made of resin is provided between the input shaft and the output shaft.

3. 3. The reducer according to claim 1, wherein the resin material forming the outer rollers of the internal gear has a limit PV value of 2 MPa·m / s or more.

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