Reduction gear and rotating device

Abstract

To achieve a low noise level by reducing noise which is generated from an engagement portion of an input gear and a plurality of transmission gears.SOLUTION: A reduction gear includes: a carrier part 12 which is arranged so as to be rotatable inside an outer cylinder 11 and fixedly installed on an output shaft; an input shaft 3 provided in a drive source; at least one crankshaft 13 rotatably supported on the carrier part 12, connected to the input shaft 3, and having an eccentric part which is decentered relative to a rotation axis of the output shaft; oscillation gears 14, 16 which oscillate and rotate together with the eccentric part of the crankshaft 13; a plurality of spur gears 20 which rotate in conjunction with the oscillation rotation of the oscillation gears 14, 16, and arranged coaxially with the plurality of crankshafts 13; and an input gear 30 which is provided on the input shaft 3 and mesh with the plurality of spur gears 20 to synchronously rotate the plurality of spur gears 20. The number of teeth at which the input gear 30 and the spur gears 20 mesh with each other is 6 to 8.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a reducer and a rotating device. [Background technology]

[0002] For example, in industrial robots, machine tools, etc., a motor unit for driving the arms is provided at the joint (joint) of a pair of rotatably connected arms. The motor unit includes a motor and a reducer connected to the motor, and the motor torque generated by the rotation of the motor is reduced by the reducer and output to the arm.

[0003] For such industrial robots, progress is being made in the development of reducers for use in robots that can work in collaboration with workers (see, for example, Patent Document 1). Patent Document 1 describes a reducer that has multiple spur gears (transmission gears), in which an input gear meshes with each of the multiple spur gears and rotates these spur gears synchronously. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-72842 A Summary of the Invention [Problem to be solved by the invention]

[0005] Since industrial robots such as those described above are installed in close proximity to workers, there is a demand for their operating noise to be reduced to a level that does not bother the workers.However, in the case of precision reduction gears used in industrial robots, the input gear rotates at a higher speed than other parts, which tends to generate loud noise at the meshing points between the input gear and multiple spur gears (transmission gears), so there has been a demand for reducing the noise at these meshing points.

[0006] The present invention provides a reducer and a rotating device that can achieve a low noise level by reducing noise generated from the meshing portion between an input gear and a plurality of transmission gears. [Means for solving the problem]

[0007] A reducer according to one embodiment of the present invention includes an outer cylinder having a plurality of internal teeth surrounding a rotating shaft, a carrier portion rotatably arranged inside the outer cylinder and fixedly installed on an output shaft, an input shaft provided in a drive source, at least one crankshaft rotatably supported on the carrier portion, connected to the input shaft, and having an eccentric portion eccentric with respect to the rotation axis of the output shaft, an oscillating gear that oscillates and rotates together with the eccentric portion of the crankshaft, a plurality of transmission gears that rotate together with the oscillating rotation of the oscillating gear and are provided coaxially with each of the plurality of crankshafts, and an input gear that is provided on the input shaft, meshes with the plurality of transmission gears, and rotates the plurality of transmission gears synchronously, the number of teeth that mesh between the input gear and the transmission gear being 6 to 8.

[0008] With this configuration, the number of teeth that mesh between the input gear and the transmission gear is 6 to 8, so that it is possible to reduce noise generated from the meshing portion between the input gear and the multiple transmission gears. This makes it possible to apply high-tooth gears that are provided with multiple transmission gears, and realizes a reducer that achieves a low noise level. For example, this is effective for applying precision reducers to industrial robots, etc.

[0009] A reducer according to another aspect of the present invention comprises an outer cylinder having a plurality of internal teeth formed around a rotating shaft, a carrier portion rotatably mounted inside the outer cylinder and fixed to an output shaft, an input shaft provided in a drive source, at least one crankshaft rotatably supported by the carrier portion, connected to the input shaft, and having an eccentric portion eccentric with respect to the rotation axis of the output shaft, an oscillating gear that oscillates and rotates together with the eccentric portion of the crankshaft, a plurality of transmission gears that rotate together with the oscillating rotation of the oscillating gear and are provided coaxially with each of the plurality of crankshafts, and an input gear that is provided on the input shaft, meshes with the plurality of transmission gears, and rotates the plurality of transmission gears synchronously, wherein a tooth addendum coefficient of the input gear and the transmission gear is 1.2 or more and 1.3 or less, and a tooth base coefficient is greater than 1.25 and less than 1.55.

[0010] With this configuration, the tooth addendum coefficient of the input gear and the transmission gear is set to 1.2 or more and 1.3 or less, and the tooth base coefficient is set to 1.25 or more and 1.55 or less, so that it is possible to reduce noise generated from the meshing portion between the input gear and the multiple transmission gears. This makes it possible to apply high teeth with multiple transmission gears, and realizes a reducer that achieves a low noise level. For example, this is effective for applying precision reducers to industrial robots, etc.

[0011] It is desirable that the pressure angle of the input gear and the transmission gear is 14.5° or more and 20.0° or less, the tooth thickness is 3 mm or more and 30 mm or less, and the module (pitch circle diameter / number of teeth) is 0.8 or more and 3.0 or less.

[0012] A reducer according to another aspect of the present invention includes an outer cylinder having a plurality of internal teeth surrounding a rotating shaft, a carrier portion rotatably provided inside the outer cylinder and fixedly installed on an output shaft, an input shaft provided in a drive source, at least one crank shaft rotatably supported on the carrier portion, connected to the input shaft, and having an eccentric portion eccentric with respect to the rotation axis of the output shaft, an oscillating gear that oscillates and rotates together with the eccentric portion of the crank shaft, a plurality of transmission gears that rotate together with the oscillating rotation of the oscillating gear and are provided coaxially with each of the plurality of crank shafts, and an input gear that is provided on the input shaft, meshes with the plurality of transmission gears, and rotates the plurality of transmission gears synchronously, wherein the number of teeth that mesh between the input gear and the transmission gear is 6 to 8, the pressure angle of the input gear and the transmission gear is 14.5° or more and 20.0° or less, the tooth thickness is 3 mm or more and 30 mm or less, and the module (pitch circle diameter / number of teeth) is 0.8 or more and 3.0 or less.

[0013] With this configuration, the number of teeth that mesh between the input gear and the transmission gear is 6 to 8, so that it is possible to reduce noise generated from the meshing portion between the input gear and the multiple transmission gears. This makes it possible to apply high-tooth gears that are provided with multiple transmission gears, and realizes a reducer that achieves a low noise level. For example, this is effective for applying precision reducers to industrial robots, etc. Furthermore, in the present invention, the pressure angles of the input gear and the transmission gear are set to 14.5° or more and 20.0° or less, the tooth thickness is set to 3 mm or more and 30 mm or less, and the module (pitch circle diameter / number of teeth) is set to 0.8 or more and 3.0 or less, thereby making it possible to further reduce the noise generated from the meshing portions between the input gear and multiple transmission gears.

[0014] A reducer according to another aspect of the present invention includes an outer cylinder having a plurality of internal teeth formed around a rotating shaft, a carrier portion rotatably disposed inside the outer cylinder and fixed to an output shaft, an input shaft provided in a drive source, at least one crankshaft rotatably supported by the carrier portion, connected to the input shaft, and having an eccentric portion eccentric with respect to a rotation axis of the output shaft, an oscillating gear that oscillates and rotates together with the eccentric portion of the crankshaft, and a gear for each of the crankshafts that rotates together with the oscillating rotation of the oscillating gear. The input gear has a plurality of transmission gears provided coaxially with the input shaft, and an input gear provided on the input shaft, meshing with the plurality of transmission gears and rotating the plurality of transmission gears synchronously, wherein the tooth addendum coefficient of the input gear and the transmission gear is 1.2 or more and 1.3 or less, and the tooth base coefficient is greater than 1.25 and 1.55 or less, the pressure angle of the input gear and the transmission gear is 14.5° or more and 20.0° or less, the tooth thickness is 3 mm or more and 30 mm or less, and the module (pitch circle diameter / number of teeth) is 0.8 or more and 3.0 or less.

[0015] With this configuration, the tooth addendum coefficient of the input gear and the transmission gear is set to 1.2 or more and 1.3 or less, and the tooth base coefficient is set to 1.25 or more and 1.55 or less, so that it is possible to reduce noise generated from the meshing portion between the input gear and the multiple transmission gears. This makes it possible to apply high teeth with multiple transmission gears, and realizes a reducer that achieves a low noise level. This makes it effective to apply precision reducers to industrial robots, etc. Furthermore, in the present invention, the pressure angles of the input gear and the transmission gear are set to 14.5° or more and 20.0° or less, the tooth thickness is set to 3 mm or more and 30 mm or less, and the module (pitch circle diameter / number of teeth) is set to 0.8 or more and 3.0 or less, thereby making it possible to further reduce the noise generated from the meshing portions between the input gear and multiple transmission gears.

[0016] A rotating device according to one aspect of the present invention includes a device main body, a rotating body having a working head, a motor provided in the device main body for rotating the rotating body by a driving force, and a reducer for reducing the rotation speed of the motor. The reducer includes an outer cylinder having a plurality of internal teeth surrounding a rotating shaft, a carrier portion rotatably provided inside the outer cylinder and fixed to an output shaft, an input shaft provided in a driving source, at least one crankshaft rotatably supported by the carrier portion, connected to the input shaft, and having an eccentric portion eccentric with respect to the rotation axis of the output shaft, an oscillating gear that oscillates and rotates together with the eccentric portion of the crankshaft, a plurality of transmission gears that rotate together with the oscillating rotation of the oscillating gear and are provided coaxially with each of the plurality of crankshafts, and an input gear provided on the input shaft, meshing with the plurality of transmission gears and rotating the plurality of transmission gears synchronously, the number of teeth that mesh between the input gear and the transmission gear is 6 to 8.

[0017] With this configuration, the number of teeth that mesh between the input gear and the transmission gear is 6 to 8, which reduces noise generated from the meshing portion between the input gear and the multiple transmission gears. Therefore, it is effective to apply the precision reduction gear to a rotating device such as an industrial robot that includes a device main body, a rotating body equipped with a working head, a motor provided in the device main body for rotating the rotating body with a driving force, and a reduction gear for reducing the rotation of the motor.

[0018] A rotation device according to another aspect of the present invention includes a device main body, a rotor having a working head, a motor provided in the device main body for rotating the rotor by a driving force, and a reducer for reducing the rotation speed of the motor, the reducer including an outer cylinder having a plurality of internal teeth surrounding a rotation axis, a carrier portion provided rotatably inside the outer cylinder and fixed to an output shaft, an input shaft provided in a drive source, and a rotation axis of the output shaft that is eccentrically disposed relative to the rotation axis of the output shaft and rotatably supported by the carrier portion and connected to the input shaft. the input gear is provided on the input shaft, meshes with the transmission gears, and rotates synchronously with the transmission gears; a tooth addendum coefficient of the input gear and the transmission gear is 1.2 or more and 1.3 or less, and a tooth base coefficient of the input gear and the transmission gear is greater than 1.25 and is 1.55 or less.

[0019] With this configuration, the tooth addendum coefficient of the input gear and the transmission gear is set to 1.2 or more and 1.3 or less, and the tooth base coefficient is set to greater than 1.25 and 1.55 or less, thereby making it possible to reduce noise generated from the meshing portion between the input gear and the multiple transmission gears. Therefore, the precision reduction gear is effectively applied to a rotating device such as an industrial robot that includes a device main body, a rotating body equipped with a working head, a motor provided in the device main body for rotating the rotating body with a driving force, and a reduction gear for reducing the rotation of the motor. Effect of the Invention

[0020] The above-described speed reducer and rotating device can achieve a low noise level by reducing noise generated from the meshing portion between the input gear and the multiple transmission gears. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a side view of an industrial robot including a reducer according to an embodiment. [Diagram 2]FIG. 2 is a schematic front view of the reducer according to the embodiment. [Diagram 3] 3 is a cross-sectional view of the reducer of the embodiment taken along line II in FIG. 2. [Figure 4] FIG. 4 is an enlarged view of a main portion of a meshing portion between an input gear and a spur gear in the reducer according to the embodiment. [Diagram 5] FIG. 4 is a diagram showing the results of sound pressure measurement in an embodiment and a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Next, an embodiment of the present invention will be described with reference to the drawings. In the embodiments and modifications described below, the same reference numerals are used to designate common parts, and some overlapping descriptions will be omitted.

[0023] FIG. 1 is a side view of an industrial robot 100 that employs a reducer 1 provided in a motor with a reducer in its drive section. The industrial robot 100 (rotating device) of this embodiment is an industrial robot used for tasks such as supplying, carrying out, transporting, and assembling parts of precision equipment, etc. The industrial robot 100 includes a base 110 (device main body), a first arm 120 (rotating body), a second arm 130 (rotating body), a work head 140, and an end effector 150.

[0024] A first arm 120 rotatable around an axis O1 is connected to the base 110. A second arm 130 rotatable around an axis parallel to the axis O1 is connected to the first arm 120. A working head 140 to which an end effector 150 is connected is provided at the tip of the second arm 130. A motor 160 such as a servo motor and a reducer 1 for reducing the rotation of the motor 160 are provided inside the base 110. The first arm 120 is rotated by the driving force of the motor 160. An input shaft 3 (described later) of the reducer 1 is connected to the rotating shaft of the motor 160, and an output shaft of the reducer 1 is connected to the first arm 120. When the driving force of the motor 160 is transmitted to the first arm 120 via the reducer 1, the first arm 120 rotates around the axis O1 within a horizontal plane.

[0025] 1, the reducer 1 is provided at a connection portion (joint portion) of a first arm 120 that is rotatably connected to the above-mentioned industrial robot 100. The reducer 1 reduces the motor torque input from a motor 160 serving as a power source at a predetermined reduction ratio and outputs the reduced torque to the output shaft side. In other words, the reducer 1 converts the rotation speed at a predetermined rotation speed ratio between the power source, which is the first member, and a mechanical part such as an arm to transmit a driving force.

[0026] In the description of the embodiment, the direction along the axis O1 (see FIG. 1) of the motor 160 of the reducer 1 is simply referred to as the axial direction, the direction intersecting the axis O1 as viewed from the axial direction is referred to as the radial direction, and the direction going around the axis O1 is referred to as the circumferential direction. With respect to the axial direction, the side facing the inside of the object is referred to as the axial inner side, and the opposite side is referred to as the axial outer side. Also, the side to which the drive source is connected to the reducer 1 is referred to as the input side, and the side to which the mechanical part such as the arm described above that receives the output of the reducer 1 is connected is referred to as the output side.

[0027] Fig. 2 is a schematic front view of the reducer 1 as viewed from the input side in the direction of the axis O1. As shown in Fig. 2, the reducer 1 includes three spur gears 20 (20A, 20B, 20C) that correspond to transmission gears, and an input gear 30 that corresponds to an input gear. The spur gears 20A, 20B, 20C are each formed as an involute gear. Similarly, the input gear 30 is also formed as an involute gear.

[0028] 2 shows an axis O1 which is the rotation axis of the input gear 30, and transmission axes C1, C2, and C3 of the three spur gears 20A, 20B, and 20C. The transmission axes C1, C2, and C3 are arranged at approximately equal intervals on a virtual circle centered on the axis O1. The input gear 30 rotates around the axis O1. The first spur gear 20A rotates around the first transmission axis C1. The second spur gear 20B rotates around the second transmission axis C2. The third spur gear 20C rotates around the third transmission axis C3. A plurality of (e.g., three) spur gears 20 and the input gear 30 are exposed on the input side of the reducer 1.

[0029] The input gear 30 meshes with the spur gears 20A, 20B, and 20C to transmit driving force. External teeth 30a are provided on the outer circumferential surface at the tip of the input gear 30. The external teeth 30a mesh with the external teeth 20a of each of the spur gears 20A, 20B, and 20C. When the input gear 30 rotates around the axis O1, the spur gears 20A, 20B, and 20C rotate synchronously.

[0030] 3 is a cross-sectional view of the reducer 1 according to the embodiment (a view cut along a plane including the axis O1 shown in FIG. 1), taken along line II in FIG.

[0031] The reducer 1 according to this embodiment is configured to rotate the crankshaft 13 by rotating the input shaft 3 having the input gear 30, and to oscillate and rotate the oscillating gears 14 and 16 in conjunction with the eccentric parts 13B and 13C of the crankshaft 13, thereby obtaining an output rotation reduced from the input rotation. The central axes of the three crankshafts 13 coincide with the transmission axes C1, C2, and C3, respectively. In other words, the rotation of the three crankshafts 13 is transmitted to the first oscillating gear 14 and the second oscillating gear 16 arranged in the internal space surrounded by the outer cylinder 11 and the carrier part 12.

[0032] As shown in Figures 2 and 3, the reducer 1 comprises an outer tube 11, a carrier portion 12 fixed to the industrial robot 100, the above-mentioned input shaft 3, a plurality of (e.g., three) crank shafts 13 rotatably supported by the carrier portion 12, a first oscillating gear 14, a second oscillating gear 16, and the above-mentioned plurality of (e.g., three) spur gears 20 (20A, 20B, 20C). The three spur gears 20A, 20B, 20C are respectively assembled to the three crankshafts 13. The first oscillating gear 14 and the second oscillating gear 16 are disposed around the crankshaft 13.

[0033] The outer cylinder 11 constitutes the outer surface of the reducer 1 and has a cylindrical shape. A large number of pin grooves 11b are formed on the inner peripheral surface of the outer cylinder 11. Each pin groove 11b is disposed to extend in the axial direction of the outer cylinder 11 and has a semicircular cross-sectional shape in a cross section perpendicular to the axial direction. These pin grooves 11b are arranged at equal intervals in the circumferential direction on the inner peripheral surface of the outer cylinder 11. The outer cylinder 11 cooperates with the carrier portion 12 to form a cylindrical internal space in which the crankshaft 13, the first oscillating gear 14, and the second oscillating gear 16 are housed.

[0034] The outer cylinder 11 has a large number of internally toothed pins 4. Each internally toothed pin 4 is a substantially cylindrical member extending in the axial direction, and is attached to each pin groove 11b. Specifically, each internally toothed pin 4 is fitted into the corresponding pin groove 11b, and is arranged in a position extending in the axial direction of the outer cylinder 11. As a result, the large number of internally toothed pins 4 are lined up at equal intervals along the circumferential direction of the outer cylinder 11. The first external teeth 14a of the first oscillating gear 14 and the second external teeth 16a of the second oscillating gear 16 mesh with these internally toothed pins 4.

[0035] The carrier part 12 is accommodated in the outer cylinder 11 while being disposed coaxially with the outer cylinder 11. The carrier part 12 rotates relative to the outer cylinder 11 about the same axis. Specifically, the carrier part 12 is disposed radially inside the outer cylinder 11, and in this state, is supported by a pair of main bearings 17 spaced apart from each other in the axial direction so as to be rotatable relative to the outer cylinder 11.

[0036] The carrier portion 12 includes a base portion having a base plate portion 12A and a plurality of (eg, three) shaft portions 12C, and an end plate portion 12B.

[0037] The base plate portion 12A is disposed near one end in the axial direction within the outer cylinder 11. A circular through hole 12a is provided in the radial center of the base plate portion 12A. A plurality of (e.g., three) crankshaft mounting holes (hereinafter simply referred to as mounting holes 12b) are provided around the through hole 12a at equal intervals in the circumferential direction. A crankshaft 13 is disposed inside each of the three mounting holes 12b. The center lines of the mounting holes 12b extending in the axial direction coincide with the transmission shafts C1, C2, and C3, respectively.

[0038] The end plate portion 12B is provided axially apart from the base plate portion 12A, and is disposed in the outer cylinder 11 near the other end in the axial direction. A through hole 12c is provided in the radial center of the end plate portion 12B. Around the through hole 12c, a plurality of (e.g., three) crankshaft mounting holes (hereinafter simply referred to as mounting holes 12d) are provided at positions corresponding to the plurality of mounting holes 12b of the base plate portion 12A. Within the outer cylinder 11, a closed space is formed that is surrounded by the inner surfaces of both the end plate portion 12B and the base plate portion 12A facing each other, and the inner peripheral surface of the outer cylinder 11.

[0039] The three shaft portions 12C are integral with the base plate portion 12A and extend linearly from one main surface (inner surface) of the base plate portion 12A toward the end plate portion 12B. The three shaft portions 12C are disposed at equal intervals in the circumferential direction. Each shaft portion 12C is fastened to the end plate portion 12B by a bolt 12e. This integrates the base plate portion 12A, the shaft portions 12C, and the end plate portion 12B.

[0040] The input shaft 3 functions as an input section to which the driving force of a drive motor (motor 160 shown in FIG. 1) is input. The input shaft 3 is disposed so that its axis coincides with the axis of the outer tube 11 and the carrier section 12, and rotates about its axis. An input gear 30 is provided on the outer peripheral surface of the tip of the input shaft 3.

[0041] The three crankshafts 13 are disposed at equal intervals around the input shaft 3 inside the outer cylinder 11. Each crankshaft 13 is supported by a pair of crank bearings 13a, 13b to be rotatable about its axis relative to the carrier portion 12. Specifically, a first crankshaft bearing 13a is attached to a portion of each crankshaft 13 that is axially inward by a predetermined length from one axial end thereof, and this first crankshaft bearing 13a is attached to a mounting hole 12b of the base plate portion 12A. Meanwhile, a second crankshaft bearing 13b is attached to the other axial end of each crankshaft 13, and this second crankshaft bearing 13b is attached to a mounting hole 12d of the end plate portion 12B. As a result, the crankshaft 13 is rotatably supported by the base plate portion 12A and the end plate portion 12B.

[0042] Each crankshaft 13 has a shaft body 13A and eccentric portions 13B and 13C formed integrally with the shaft body 13A. The first eccentric portion 13B and the second eccentric portion 13C are arranged side by side in the axial direction between the portions supported by the crank bearings 13a and 13b. The first eccentric portion 13B and the second eccentric portion 13C each have a cylindrical shape, and both of them protrude radially outward from the shaft body 13A in a state of being eccentric with respect to the axis of the shaft body 13A. The first eccentric portion 13B and the second eccentric portion 13C are each eccentric from the axis by a predetermined amount, and are arranged to have a phase difference of a predetermined angle with respect to each other.

[0043] One end of the crankshaft 13 (the end on the right side in FIG. 3), i.e., a portion axially outward of the portion attached within the attachment hole 12d of the end plate portion 12B, is provided with a fitted portion 13c to which a spur gear 20 (20A, 20B, 20C) is attached. Note that the reducer 1 of the embodiment is not limited to the example of FIG. 2, and may have a configuration called a reverse assembly in which the crankshaft 13 is disposed axially inverted and the fitted portion 13c is disposed axially outward of the attachment hole 12b of the base portion 12A.

[0044] In the reduction gear 1, the durability of each crankshaft 13 can be improved by reducing the difference in torque transmitted to each crankshaft 13. Also, in the reduction gear 1, the impact transmitted to each crankshaft 13 can be reduced, thereby suppressing surface peeling of the surface of the crank portion (i.e., the surface that transmits torque from the crankshaft 13 to the spur gear 20).

[0045] The first oscillating gear 14 and the second oscillating gear 16 may be trochoid gears or cycloid gears formed based on a common design drawing. The first oscillating gear 14 is disposed in the closed space in the outer cylinder 11 and is attached to the first eccentric portion 13B of each crankshaft 13 via a first roller bearing 18a. When each crankshaft 13 rotates and the first eccentric portion 13B rotates eccentrically, the first oscillating gear 14 oscillates and rotates while meshing with the internal tooth pin 4 in conjunction with the eccentric rotation.

[0046] The first oscillating gear 14 has a size slightly smaller than the inner diameter of the outer cylinder 11. The first oscillating gear 14 has first external teeth 14a, a central through-hole 14b, a plurality (e.g., three) of first eccentric portion insertion holes 14c, and a plurality (e.g., three) of shaft portion insertion holes 14d. The first external teeth 14a have a wave shape that is smoothly continuous over the entire circumferential direction of the first oscillating gear 14.

[0047] The central through-hole 14b is provided in the radial center of the first oscillating gear 14. The three first eccentric portion insertion holes 14c are provided at equal intervals in the circumferential direction around the central through-hole 14b in the first oscillating gear 14. The first eccentric portion 13B of each crankshaft 13 is inserted into each first eccentric portion insertion hole 14c via a first roller bearing 18a on the inner wall side of each first eccentric portion insertion hole 14c.

[0048] The three shaft portion insertion holes 14d are provided at equal intervals in the circumferential direction around the central through hole 14b of the first oscillating gear 14. Each shaft portion insertion hole 14d is disposed at a position between the three first eccentric portion insertion holes 14c in the circumferential direction. The corresponding shaft portion 12C is inserted into each shaft portion insertion hole 14d with some play.

[0049] The second oscillating gear 16 is disposed in the closed space in the outer cylinder 11 and is attached to the second eccentric portion 13C of each crankshaft 13 via a second roller bearing 18b. The first oscillating gear 14 and the second oscillating gear 16 are arranged side by side in the axial direction in accordance with the arrangement of the first eccentric portion 13B and the second eccentric portion 13C. When each crankshaft 13 rotates and the second eccentric portion 13C rotates eccentrically, the second oscillating gear 16 oscillates and rotates while meshing with the internal tooth pin 4 in conjunction with the eccentric rotation.

[0050] The second oscillating gear 16 has a size slightly smaller than the inner diameter of the outer cylinder 11, and has the same configuration as the first oscillating gear 14. That is, the second oscillating gear 16 has second external teeth 16a, a central through hole 16b, a plurality (e.g., three) second eccentric portion insertion holes 16c, and a plurality (e.g., three) shaft portion insertion holes 16d. These have the same structure as the first external teeth 14a, the central through hole 14b, the plurality of first eccentric portion insertion holes 14c, and the plurality of shaft portion insertion holes 14d of the first oscillating gear 14. The second eccentric portion 13C of the crankshaft 13 is inserted into each second eccentric portion insertion hole 16c via a second roller bearing 18b on the inner wall side of each second eccentric portion insertion hole 16c.

[0051] The spur gears 20A, 20B, and 20C transmit the rotation of the input gear 30 to the corresponding crankshaft 13. Each of the spur gears 20A, 20B, and 20C is fitted into a fitted portion 13c provided at one end of the shaft body 13A of the corresponding crankshaft 13. Each of the spur gears 20A, 20B, and 20C rotates integrally with the crankshaft 13 around the same axis as the rotation axis of the crankshaft 13. Each of the spur gears 20A, 20B, and 20C has external teeth 20a that mesh with the input gear 30.

[0052] One of the outer cylinder 11 and the carrier part 12 is rotated around an axis O1 by a driving force transmitted to the crankshaft 13, the first oscillating gear 14, and the second oscillating gear 16. The other of the outer cylinder 11 and the carrier part 12 is fixed to a first arm 120 (see FIG. 1) of the industrial robot 100 to which the reducer 1 is attached.

[0053] Since the spur gears 20 (20A, 20B, 20C) are involute gears, noise generated from the meshing portions between the spur gears 20A, 20B, 20C and the input gear 30 tends to be larger than noise generated from the meshing portions between the first oscillating gear 14 and the second oscillating gear 16 of the trochoid gears and the external cylinder 11. Therefore, in this embodiment, the number of teeth that mesh between the external teeth 20a of the spur gear 20 and the external teeth 30a of the input gear 30 of the input shaft 3 is set to 6 to 8. In this case, noise generated from the meshing portions between the first oscillating gear 14 and the second oscillating gear 16 and the external cylinder 11 is suppressed to a very low level.

[0054] 4 is an enlarged view of a portion where the external teeth 20a of the spur gear 20 mesh with the external teeth 30a of the input gear 30. Next, the external teeth 20a of the spur gear 20 and the external teeth 30a of the input gear 30 of the input shaft 3 employed in this embodiment will be described in more detail with reference to FIG.

[0055] In the following description, the term "tooth profile direction" refers to the direction extending from the tooth base to the tooth tip or from the tooth tip to the tooth base. The tooth shapes and dimensions of the external teeth 20a of each of the spur gears 20A, 20B, and 20C and the external teeth 30a of the input gear 30 in this embodiment will be described below. Note that the following numerical values ​​are common to the external teeth 20a of the spur gear 20 and the external teeth 30a of the input gear 30.

[0056] In this embodiment, the tooth addendum coefficient (h1) of the external teeth 20a and 30a is set to 1.2 or more and 1.3 or less, and the tooth base coefficient (h2) is set to more than 1.25 and less than 1.55. In other words, the total tooth depth h0 is the sum (=h1+h2) of the tooth addendum coefficient (h1) and the tooth base coefficient (h2), which is more than 2.45 and less than 2.75. The lower limit of the tooth addendum coefficient (h1) is physically set to 1.2 or more to increase the meshing ratio to 2 or more. The lower limit of the tooth base coefficient (h2) is set to be greater than 1.25 to increase the meshing ratio and improve the noise reduction effect.

[0057] In this embodiment, the pressure angle α of the external teeth 20a and 30a is set to 14.5° or more and 20.0° or less, the tooth thickness s is set to 3 mm or more and 30 mm or less, and the module m (pitch circle diameter d / number of teeth Z) is set to 0.8 or more and 3.0 or less. The upper limit of the pressure angle α is set to 20.0°, which is a commonly used angle. The lower limit of the pressure angle α is set to 14.5° or more to increase the meshing ratio. If the pressure angle α is smaller than 14.5°, the teeth will break or be damaged in a precision reducer with a large torque. The numerical range of the tooth thickness s (3 mm or more and 30 mm or less) is the range of a commonly used precision reducer. In other words, if the tooth thickness s is less than 3 mm, a large edge load will be generated at the meshing portion, and an effective contact width cannot be secured, resulting in noise. If the tooth thickness s is larger than 30 mm, the precision reducer will elongate in the thickness direction. The numerical range of the module m (0.8 or more and 3.0 or less) is the range of a commonly used precision reducer. That is, if the module m is less than 0.8, when the tooth depth is extended, the top land of the tooth becomes too small, which makes manufacturing difficult, for example by causing cracks during heat treatment. If the module m is more than 3.0, the number of teeth becomes too small, making it impossible to achieve a meshing ratio of 2 or more.

[0058] Table 1 and FIG. 5 show test results of measuring sound pressure (dBA) when the input rotation speed (rpm) was changed for the reducer 1 according to the embodiment having the external teeth 20a of the spur gears 20A, 20B, 20C and the external teeth 30a of the input gear 30 set within the numerical ranges described above, and for a reducer according to a comparative example having conditions outside the numerical ranges described above.

[0059] [Table 1]

[0060] In the embodiment, the setting conditions of the external teeth 20a of the spur gear 20 and the external teeth 30a of the input gear 30 are as follows: module m is 1.25, tooth thickness s is 14.5 mm, addendum coefficient h1 is 1.3, root coefficient h2 is 1.55, and pressure angle α is 20°. In the comparative example, the setting conditions of the external teeth 20a of the spur gear 20 and the external teeth 30a of the input gear 30 are as follows: module m is 1.25, tooth thickness s is 14.5 mm, addendum coefficient h1 is 1, root coefficient h2 is 1.25, and pressure angle α is 20°.

[0061] The rotation conditions of the reducer used in the embodiment and comparative example were a total speed ratio of 236.36, a torque load on the reducer of 4900 Nm, and a moment load on the reducer of 11000 Nm. In the test, the sound pressure (dBA) was measured when the input rotation speed was changed in increments of 500 rpm from 500 rpm to 3000 rpm. In Fig. 5, "◯" indicates the embodiment, and "△" indicates the comparative example.

[0062] As shown in Table 1 and Fig. 5, the sound pressure of the embodiment is 3 to 6 dBA lower than that of the comparative example at all input rotation speeds. Therefore, it was confirmed that the embodiment can reduce the level of noise caused by the friction between the tooth surface of the external teeth 20a and the tooth surface of the external teeth 30a. Specifically, by setting the tooth addendum coefficient to 1.3 and the tooth base coefficient to 1.55, the noise level can be reduced compared to the comparative example.

[0063] As described above, the reducer 1 of this embodiment includes the outer cylinder 11 on which a plurality of internal teeth are formed surrounding the rotating shaft, the carrier portion 12 rotatably provided inside the outer cylinder 11 and fixedly installed on the output shaft, the input shaft 3 provided on the drive source, at least one crankshaft 13 rotatably supported by the carrier portion 12 and connected to the input shaft 3, and having an eccentric portion eccentric with respect to the rotation axis of the output shaft, and the oscillating gears 14 and 15 that oscillate and rotate together with the eccentric portion of the crankshaft 13. 6, a plurality (three) of spur gears 20A, 20B, 20C which rotate together with the oscillating rotation of the oscillating gears 14, 16 and are provided coaxially with each of the plurality of crankshafts 13, and an input gear 30 which is provided on the input shaft 3 and meshes with the plurality of spur gears 20A, 20B, 20C to rotate the plurality of spur gears 20A, 20B, 20C synchronously, the number of teeth which mesh between the input gear 30 and the spur gears 20A, 20B, 20C being 6 to 8. Therefore, the number of teeth that mesh between the input gear 30 and the spur gears 20A, 20B, and 20C is 6 to 8, which reduces noise generated from the meshing portion between the input gear 30 and the multiple spur gears 20A, 20B, and 20C. This makes it possible to apply high teeth provided with multiple spur gears 20A, 20B, and 20C, and realizes a reducer 1 that achieves a low noise level. Application of the precision reducer to the industrial robot 100 and the like as described above becomes effective.

[0064] In this embodiment, the drive source includes an outer cylinder 11 having a plurality of internal teeth formed thereon surrounding a rotation axis, a carrier portion 12 rotatably provided inside the outer cylinder 11 and fixed to an output shaft, an input shaft 3 provided in the drive source, at least one crankshaft 13 rotatably supported by the carrier portion 12, connected to the input shaft 3, and having an eccentric portion eccentric with respect to the rotation axis of the output shaft, oscillating gears 14 and 16 that oscillate and rotate together with the eccentric portion of the crankshaft 13, and an oscillating gear of the oscillating gears 14 and 16. The input gear 30 has a tooth addendum coefficient of 1.2 or more and 1.3 or less, and a tooth base coefficient of 1.25 or more and 1.55 or less. The input gear 30 and the spur gears 20A, 20B, 20C have a tooth addendum coefficient of 1.2 or more and 1.3 or less, and a tooth base coefficient of 1.25 or more and 1.55 or less. The input gear 30 has a tooth addendum coefficient of 1.25 ... In this case, the tooth addendum coefficient between the input gear 30 and the spur gears 20A, 20B, 20C is set to 1.2 or more and 1.3 or less, and the tooth base coefficient is set to be greater than 1.25 and less than 1.55, so that it is possible to reduce noise generated from the meshing portion between the input gear 30 and the multiple spur gears 20A, 20B, 20C. This makes it possible to apply high teeth provided with the multiple spur gears 20A, 20B, 20C, and realizes a reducer 1 that achieves a low noise level. It is effective to apply a precision reducer to the industrial robot 100 and the like as described above.

[0065] In the reducer 1 of this embodiment, it is preferable that the pressure angle of the input gear 30 and the spur gears 20A, 20B, and 20C is 14.5° or more and 20.0° or less, the tooth thickness is 3 mm or more and 30 mm or less, and the module (pitch circle diameter / number of teeth) is 0.8 or more and 3.0 or less. In this case, the pressure angle of the input gear 30 and the spur gears 20A, 20B, 20C is set to 14.5° or more and 20.0° or less, the tooth thickness is set to 3 mm or more and 30 mm or less, and the module (pitch circle diameter / number of teeth) is set to 0.8 or more and 3.0 or less, so that the noise generated from the meshing portions between the input gear 30 and the multiple spur gears 20A, 20B, 20C can be further reduced.

[0066] Furthermore, in this embodiment, there is provided a base 110, a first arm 120 equipped with a work head 140, a second arm 130, a motor 160 provided on the base 110 for rotating the first arm 120 and the second arm 130 by a driving force, and a reducer 1 for reducing the rotation of the motor 160. The reducer 1 includes an outer cylinder 11 having a plurality of internal teeth surrounding a rotating shaft, a carrier portion 12 rotatably mounted inside the outer cylinder 11 and fixed to the output shaft, an input shaft 3 provided in a drive source, at least one crankshaft 13 rotatably supported by the carrier portion 12, connected to the input shaft 3, and having an eccentric portion eccentric with respect to the rotation axis of the output shaft, oscillating gears 14, 16 that oscillate and rotate together with the eccentric portion of the crankshaft 13, a plurality of spur gears 20A, 20B, 20C that rotate together with the oscillating rotation of the oscillating gears 14, 16 and are provided coaxially with each of the plurality of crankshafts 13, and an input gear 30 that is provided on the input shaft 3, meshes with the plurality of spur gears 20A, 20B, 20C, and rotates the plurality of spur gears 20A, 20B, 20C synchronously. The input gear 30 and the spur gears 20A, 20B, and 20C mesh with each other with six to eight teeth. Therefore, since the number of teeth that mesh between the input gear 30 and the spur gears 20A, 20B, 20C is 6 to 8, it is possible to reduce noise generated from the meshing portions between the input gear 30 and the plurality of spur gears 20A, 20B, 20C. Therefore, it is effective to apply the precision reduction gear to a rotating device such as an industrial robot 100 that includes a base 110, a first arm 120 and a second arm 130 each having a working head 140, a motor 160 provided on the base 110 for rotating the first arm 120 and the second arm 130 by a driving force, and a reduction gear 1 for reducing the rotation speed of the motor 160.

[0067] Furthermore, in this embodiment, there is provided a base 110, a first arm 120 equipped with a work head 140, a second arm 130, a motor 160 provided on the base 110 for rotating the first arm 120 and the second arm 130 by a driving force, and a reducer 1 for reducing the rotation of the motor 160. The reducer 1 includes an outer cylinder 11 having a plurality of internal teeth surrounding a rotating shaft, a carrier portion 12 rotatably mounted inside the outer cylinder 11 and fixed to the output shaft, an input shaft 3 provided in a drive source, at least one crankshaft 13 rotatably supported by the carrier portion 12, connected to the input shaft 3, and having an eccentric portion eccentric with respect to the rotation axis of the output shaft, oscillating gears 14, 16 that oscillate and rotate together with the eccentric portion of the crankshaft 13, a plurality of spur gears 20A, 20B, 20C that rotate together with the oscillating rotation of the oscillating gears 14, 16 and are provided coaxially with each of the plurality of crankshafts 13, and an input gear 30 that is provided on the input shaft 3, meshes with the plurality of spur gears 20A, 20B, 20C, and rotates the plurality of spur gears 20A, 20B, 20C synchronously. The tooth addendum coefficient of the input gear 30 and the spur gears 20A, 20B, and 20C is 1.2 or more and 1.3 or less, and the tooth base coefficient is greater than 1.25 and less than 1.55. Therefore, since the tooth addendum coefficient between the input gear 30 and the spur gears 20A, 20B, 20C is set to 1.2 or more and 1.3 or less, and the tooth base coefficient is set to be greater than 1.25 and less than 1.55, it is possible to reduce noise generated from the meshing portions between the input gear 30 and the plurality of spur gears 20A, 20B, 20C. Therefore, it is effective to apply the precision reduction gear to a rotating device such as an industrial robot 100 including a base 110, a first arm 120 and a second arm 130 including a work head 140, a motor 160 provided on the base 110 for rotating the first arm 120 and the second arm 130 by a driving force, and a reduction gear 1 for reducing the rotation speed of the motor 160.

[0068] The reducer 1 of the above-described embodiment is able to achieve a low noise level by reducing the noise generated from the meshing portion between the input gear 30 and the multiple (three) spur gears 20.

[0069] The present invention is not limited to the above-described embodiment, and various design modifications are possible without departing from the spirit and scope of the present invention.

[0070] For example, in the above embodiment, there are configurations including a configuration (first configuration) in which the number of meshing teeth between the input gear 30 and the spur gear 20 is 6 to 8, a configuration (second configuration) in which the tooth addendum coefficient of the input gear 30 and the spur gear 20 is 1.2 or more and 1.3 or less, and the tooth root coefficient is greater than 1.25 and 1.55 or less, and a configuration (third configuration) in which the pressure angle of the input gear 30 and the spur gear 20 is 14.5° or more and 20.0° or less, the tooth thickness is 3 mm or more and 30 mm or less, and the module is 0.8 or more and 3.0 or less, but the reducer is not limited to a configuration including all of the first, second, and third configurations. That is, by including at least one of the first and second configurations, it is possible to achieve a configuration that can reduce the noise generated from the meshing portion between the input gear 30 and the multiple (three) spur gears 20, as described above. Therefore, the above-mentioned third configuration can be omitted.

[0071] In addition, in this embodiment, the reducer 1 is configured to have one input gear 30 and three spur gears 20A, 20B, and 20C, but it is sufficient if there are multiple spur gears 20, and for example, the reducer 1 may be configured to have one input gear 30 and two spur gears 20.

[0072] In the above embodiment, the reduction gear 1 is configured to rotate the three crankshafts 13 by rotating the input shaft 3 having the input gear 30, and to oscillate and rotate the two oscillating gears 14, 16 in conjunction with the eccentric parts 13B, 13C of each crankshaft 13, thereby obtaining an output rotation reduced from the input rotation. However, the present invention is not limited to this, and the reduction gear 1 may include at least one crankshaft 13. The reduction gear 1 may be a so-called eccentric oscillating type reduction gear 1 that can obtain an output rotation by reducing the speed of the rotation of the crankshaft.

[0073] For example, an eccentric oscillating type reducer having one crankshaft will be described in more detail. In this case, the reducer has a so-called center crankshaft that is coaxial with the axis O1 as the crankshaft. As the center crankshaft rotates, the two oscillating gears 14 and 16 are oscillated and rotated.

[0074] In addition, among the embodiments disclosed in this specification, those that are configured with multiple objects may be integrated, and conversely, those that are configured with one object may be divided into multiple objects. Regardless of whether they are integrated or not, it is sufficient that they are configured to achieve the object of the invention.

[0075] In addition, in the above-described embodiment, the application of the reducer 1 has been described as an industrial robot 100, but the reducer of the present invention is not limited to this and can be applied to, for example, machine tools, automobiles, etc. [Explanation of symbols]

[0076] 1...reduction gear, 3...input shaft, 11...outer cylinder, 12...carrier portion, 13...crankshaft, 14... First oscillating gear, 16... second oscillating gear, 20, 20A, 20B, 20C... spur gear (transmission Gear), 20a...External teeth, 30...Input gear, 100...Industrial robot ( Rotating device), 110... base (device main body), 120... first arm 120 (rotating body), 130 ...Second arm (rotating body), 140...work head, O1...axis

Claims

1. an outer cylinder having a plurality of internal teeth formed thereon and surrounding a rotation shaft; a carrier portion rotatably provided inside the outer cylinder and fixed to an output shaft; an input shaft provided in the drive source; at least one crankshaft rotatably supported by the carrier portion, connected to the input shaft, and having an eccentric portion eccentric with respect to a rotation axis of the output shaft; an oscillating gear that oscillates and rotates together with the eccentric portion of the crankshaft; a transmission gear that rotates together with the oscillating rotation of the oscillating gear and is provided coaxially with the crankshaft; an input gear that is provided on the input shaft, that meshes with the transmission gear, and that causes the transmission gear to rotate synchronously, a tooth addendum coefficient of the input gear and the transmission gear is 1.2 or more and 1.3 or less, and a tooth base coefficient is 1.25 or more and 1.55 or less, A reducer in which the rate of increase in sound pressure is 0.6% or less in every 500 rpm range of input rotation speed from 1500 rpm to 3000 rpm.

2. 2. The reducer according to claim 1, wherein the input gear and the transmission gear have a pressure angle of 14.5° or more and 20.0° or less, a tooth thickness of 3 mm or more and 30 mm or less, and a module (pitch circle diameter / number of teeth) of 0.8 or more and 3.0 or less.

3. an outer cylinder having a plurality of internal teeth formed thereon and surrounding a rotation shaft; a carrier portion rotatably provided inside the outer cylinder and fixed to an output shaft; an input shaft provided in the drive source; at least one crankshaft rotatably supported by the carrier portion, connected to the input shaft, and having an eccentric portion eccentric with respect to a rotation axis of the output shaft; an oscillating gear that oscillates and rotates together with the eccentric portion of the crankshaft; a transmission gear that rotates together with the oscillating rotation of the oscillating gear and is provided coaxially with the crankshaft; an input gear that is provided on the input shaft, that meshes with the transmission gear, and that causes the transmission gear to rotate synchronously, a tooth addendum coefficient of the input gear and the transmission gear is 1.2 or more and 1.3 or less, and a tooth base coefficient is 1.25 or more and 1.55 or less, The sound pressure increase rate is 0.6% or less in every 500 rpm range of the input rotation speed from 1500 rpm to 3000 rpm, A reducer in which the pressure angle of the input gear and the transmission gear is 14.5° or more and 20.0° or less, the tooth thickness is 3 mm or more and 30 mm or less, and the module (pitch circle diameter / number of teeth) is 0.8 or more and 3.0 or less.

4. A device body, a rotating body having a working head; a motor provided in the device body for rotating the rotating body by a driving force; a reducer that reduces the rotation speed of the motor, The reducer is an outer cylinder having a plurality of internal teeth formed thereon and surrounding a rotation shaft; a carrier portion rotatably provided inside the outer cylinder and fixed to an output shaft; an input shaft provided in the drive source; at least one crankshaft rotatably supported by the carrier portion, connected to the input shaft, and having an eccentric portion eccentric with respect to a rotation axis of the output shaft; an oscillating gear that oscillates and rotates together with the eccentric portion of the crankshaft; a transmission gear that rotates together with the oscillating rotation of the oscillating gear and is provided coaxially with the crankshaft; an input gear that is provided on the input shaft, that meshes with the transmission gear, and that causes the transmission gear to rotate synchronously, a tooth addendum coefficient of the input gear and the transmission gear is 1.2 or more and 1.3 or less, and a tooth base coefficient is 1.25 or more and 1.55 or less, A rotating device in which the rate of increase in sound pressure is 0.6% or less in every 500 rpm range of input rotation speed from 1500 rpm to 3000 rpm.

Images