Speed reducer

Abstract

The invention provides a gear unit capable of reducing the tooth width of a gear and a speed reducer. The gear unit (100) comprises a first gear (1) connected with a driving source, a second gear (2) meshed with the first gear (1), a third gear (3) meshed with the first gear (1), and a fourth gear (4) meshed with the second gear (2) and the third gear (3).

Description

[0001] This application is a divisional application with application date of March 6, 2019, application number 201910167513.4, and invention name “Gear Unit and Reducer”. Technical Field

[0002] The present invention relates to a gear unit, and in particular to a gear unit that can be used in a speed reducer. Background Art

[0003] Conventionally, there is known a device for transmitting driving force, for example, a gear mechanism provided in a speed reducer in order to transmit input from a motor.

[0004] As such a gear mechanism, Patent Document 1 discloses a speed reducer having: an internal tooth member having internal teeth; a rotating member that maintains a coaxial relationship with the internal tooth member and is rotatably held on the internal tooth member; an external tooth gear having external teeth meshing with the internal teeth; and a crankshaft that receives input from the rotation of a motor to eccentrically swing the external tooth gear. A gear unit is provided between the drive shaft of the motor and the crankshaft. The gear unit is used to transmit the rotation of the drive shaft of the motor to the crankshaft.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 4658088 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] In the case of such a speed reducer, the load acting on the gears included in the gear unit is high. In order to improve the durability of the gears, it is necessary to increase the tooth width of the gears. However, if the tooth width of the gears is increased, there will be a problem that the size of the speed reducer has to be increased in the direction of the tooth width.

[0010] One object of the present invention is to provide a gear unit capable of reducing the tooth width of a gear. Other objects of the present invention are apparent from the description throughout the specification.

[0011] Solutions for solving problems

[0012] A gear unit according to one aspect of the present invention includes a first gear connected to a driving source, a second gear meshing with the first gear, a third gear meshing with the first gear, and a fourth gear meshing with the second gear and the third gear.

[0013] In the gear unit according to one aspect of the present invention, the fourth gear may have a hole in a center portion thereof, and a diameter of the fourth gear may be larger than a diameter of the second gear and a diameter of the third gear.

[0014] Alternatively, the gear unit according to one aspect of the present invention may include a support portion for rotatably supporting the fourth gear, wherein an end surface position of the support portion is substantially the same as an end surface position of the fourth gear in the rotation axis direction of the fourth gear.

[0015] In the gear unit according to one aspect of the present invention, the fourth gear may mesh with a gear set including a plurality of gears, and the second gear and the third gear may be arranged between two gears in the gear set in a circumferential direction of the fourth gear.

[0016] A speed reducer according to one aspect of the present invention includes: the gear unit described above; and a speed reduction portion for reducing the speed of input from the gear unit and outputting the reduced speed.

[0017] Effects of the Invention

[0018] According to one technical solution of the present invention, a gear unit capable of reducing the tooth width of a gear can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of a gear unit according to an embodiment of the present invention.

[0020] Figure 2 This is a schematic cross-sectional view of a speed reducer including a gear unit according to an embodiment of the present invention.

[0021] Figure 3 It is a cross-sectional view showing an eccentric oscillating speed reducer including a gear unit according to one embodiment of the present invention.

[0022] Figure 4 It is a rough representation of the Figure 3 A cross-section of the line A-A in FIG.

[0023] Figure 5 This is a schematic diagram of a conventional gear unit.

[0024] Figure 6 This is a schematic cross-sectional view of a speed reducer including a conventional gear unit.

[0025] Figure 7 This is a schematic diagram of a gear unit according to another embodiment of the present invention.

[0026] Description of Reference Numerals

[0027] 1. 1st gear; 2. 810. 2nd gear; 3. 3rd gear; 4. 220. 4th gear; 5. 5th gear; 6. 6th gear; 7. 7th gear; 9. hole; 10. gear set; 100. 100A. gear unit; 110. 120. reducer; 200. reduction unit. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0029] Reference Figure 1 and Figure 2 A gear unit 100 according to an embodiment of the present invention will be described. Figure 1 It is a schematic diagram of a gear unit 100 according to an embodiment of the present invention. Figure 2 1 is a schematic cross-sectional view of a reducer including a gear unit 100 according to an embodiment of the present invention. The gear unit 100 shown in the figure includes: a first gear (input gear) 1 connected to a drive source (not shown) such as a motor, a second gear (idle gear) 2 meshing with the first gear 1, a third gear (idle gear) 3 meshing with the first gear 1, and a fourth gear (center gear) 4 meshing with the second gear 2 and the third gear 3.

[0030] Furthermore, the diameter of the fourth gear (center gear) 4 of the illustrated gear unit 100 is configured to be larger than the diameter of the second gear 2 and the diameter of the third gear 3. A circular hole 9 is formed in the center portion of the fourth gear 4. The hole 9 extends along the rotation axis direction of the fourth gear 4. In the illustrated embodiment, the hole 9 is a through hole that penetrates the fourth gear 4 along the rotation axis direction. In addition, the gear unit 100 has a support portion 8 (see FIG. 1 ) that supports the fourth gear 4 so that it can rotate freely. Figure 2 ). The support portion 8 is, for example, a cylindrical member that fits into a hole 9 provided in the fourth gear 4. The support portion 8 is mounted to be rotatable relative to the gear frame 11 by means of, for example, a bearing 12. In the direction of the rotation axis of the fourth gear 4, the outer end surface position of the support portion 8 is substantially the same as the outer end surface position of the fourth gear 4.

[0031] The gear unit 100 also has a gear set 10, which includes a plurality of gears. In the illustrated embodiment, the gear set 10 includes three gears, namely, a fifth gear (spur gear) 5, a sixth gear (spur gear) 6, and a seventh gear (spur gear) 7. The number of gears included in the gear set 10 is not particularly limited. The fourth gear 4 of the illustrated gear unit 100 meshes with the fifth gear (spur gear) 5, the sixth gear (spur gear) 6, and the seventh gear (spur gear) 7 of the gear set 10, respectively. In the circumferential direction of the fourth gear 4, the second gear 2 and the third gear 3 are arranged between the two gears included in the gear set 10. In the illustrated embodiment, the second gear 2 and the third gear 3 are arranged between the fifth gear (spur gear) 5 and the sixth gear (spur gear) 6 of the gear set 10. According to such a structure, the torque from the first gear (input gear) 1 connected to the driving source is transmitted to the fourth gear 4 via the second gear 2 and the third gear 3, and is dispersed from the fourth gear 4 to each gear (fifth gear 5, sixth gear 6, and seventh gear 7) of the gear group 10. The power from the first gear 1 is dispersed to the second gear 2 and the third gear 3 and then transmitted to the fourth gear 4, so that the load can be suppressed from being concentrated on one part of the fourth gear 4. Therefore, the tooth width of the gear included in the gear unit 100 can be reduced.

[0032] In addition, in the illustrated gear unit 100, the second gear 2 and the third gear 3 may be arranged on the same plane. Also, in the illustrated gear unit 100, the second gear 2 and the third gear 3 may be arranged symmetrically with respect to a line connecting the centers of the first gear 1 and the fourth gear 4. Also, the second gear 2 and the third gear 3 may have the same shape and size.

[0033] Next, refer to Figure 3 and Figure 4 The structure of the eccentric oscillating speed reducer 110 including the gear unit 100 according to one embodiment of the present invention will be described. Figure 3 1 is a cross-sectional view showing an eccentric oscillating speed reducer including a gear unit 100 according to an embodiment of the present invention. Figure 4 It is a rough representation of the Figure 3 A cross-section of the line A-A in FIG.

[0034] like Figure 3 and Figure 4As shown, the eccentric oscillating reducer 110 includes: a gear unit 100, which is used to transmit torque from a driving source; and a speed reduction unit 200, which is used to reduce the speed of the input from the gear unit 100 and output it. The torque generated by the driving source is input from the first gear (input gear) of the gear unit 100, and is transmitted to the fourth gear (center gear) 220 via the second gear (idler gear) and the third gear (idler gear). Thereafter, the torque transmitted to the fourth gear (center gear) 220 is transmitted to a gear set including a spur gear 810 meshing with the fourth gear 220. As a result, the torque generated by the driving source (motor) is transmitted to the speed reduction unit. In addition, other types of gear components may also be used as the spur gear 810. The principle of the present embodiment is not limited to a specific type of gear component used as the spur gear 810.

[0035] The speed reduction unit 200 includes an outer cylinder 500, a gear frame 600, a gear unit 700, and three drive mechanisms 800 (in Figure 3 One of the three drive mechanisms 800 and two main bearings 900 are shown.

[0036] The outer cylinder 500 includes a substantially cylindrical housing 510 and a plurality of inner tooth pins 520. The housing 510 is used to define a cylindrical internal space for accommodating the gear frame 600, the gear unit 700 and the drive mechanism 800. A plurality of inner tooth pins 520 are provided on the inner side of the housing 510. Each inner tooth pin 520 is a cylindrical member extending in the extension direction of the rotation center axis RCX. Each inner tooth pin 520 is embedded in a groove formed on the inner wall of the housing 510 in a manner that its semi-circumferential surface protrudes from the inner wall of the housing 510 toward the rotation center axis RCX. The plurality of inner tooth pins 520 are arranged in a ring shape at substantially constant intervals along the inner circumferential surface of the housing 510 to form an inner tooth ring. That is, in the present embodiment, the inner teeth meshing with the first swing gear 710 and the second swing gear 720 of the gear unit 700 described later are formed by a plurality of inner tooth pins 520.

[0037] The gear frame 600 includes a base 610 and a second gear frame member 620. The base 610 is arranged between the second gear frame member 620 and the reducer arm. The gear frame 600 is cylindrical as a whole. The gear frame 600 is configured to be able to rotate relative to the outer cylinder 500. In the illustrated embodiment, the gear frame 600 rotates around the rotation center axis RCX in the outer cylinder 500.

[0038] The base 610 includes a first gear frame member 611 (see Figure 3 ) and three shaft portions 612 (see Figure 4). The three shaft portions 612 extend from the first gear frame member 611 toward the second gear frame member 620 respectively. The second gear frame member 620 is connected to the top end surface of each shaft portion 612 in the three shaft portions 612. The three shaft portions 612 respectively penetrate the gear portion 700 arranged between the first gear frame member 611 and the second gear frame member 620, and are connected to the second gear frame member 620. The second gear frame member 620 can be connected to the top end surface of each shaft portion 612 in the three shaft portions 612 by a close-fitting screw, a locating pin, or other methods.

[0039] The gear portion 700 includes a first swing gear 710 and a second swing gear 720. The first swing gear 710 is disposed between the first gear frame member 611 and the second swing gear 720. The second swing gear 720 is disposed between the second gear frame member 620 and the first swing gear 710. A portion of the plurality of external teeth of the first swing gear 710 and the second swing gear 720 meshes with an internal gear ring formed by a plurality of internal tooth pins 520.

[0040] The drive mechanism 800 includes a crankshaft 820, two journal bearings 830, and two crankshaft bearings 840. The crankshaft 820 includes a first journal 821, a second journal 822, a first eccentric portion 823, and a second eccentric portion 824. The first journal 821 is surrounded by the first gear frame member 611 of the gear frame 600. The second journal 822 is surrounded by the second gear frame member 620 of the gear frame 600. One of the two journal bearings 830 is arranged between the first journal 821 and the first gear frame member 611. The other of the two journal bearings 830 is arranged between the second journal 822 and the second gear frame member 620.

[0041] The spur gear 810 is mounted on the second journal 822, and when the spur gear 810 rotates, the crankshaft 820 also rotates. As a result, the first eccentric portion 823 and the second eccentric portion 824 rotate eccentrically. During this period, the first swing gear 710 connected to the first eccentric portion 823 via the crankshaft bearing 840 can rotate and move in the outer cylinder 500 while meshing with the plurality of internal tooth pins 520. Similarly, the second swing gear 720 connected to the second eccentric portion 824 via the crankshaft bearing 840 can rotate and move in the outer cylinder 500 while meshing with the plurality of internal tooth pins 520. As a result, both the first swing gear 710 and the second swing gear 720 can swing and rotate in the outer cylinder 500.

[0042] During the swing rotation, when viewed from the direction along the rotation center axis RCX, the center axis CX1 of the first swing gear 710 and the center axis CX2 of the second swing gear 720 respectively rotate around the rotation center axis RCX of the gear frame 600. The center axes CX1 and CX2 are axes extending substantially parallel to the rotation center axis RCX of the gear frame 600. The center axis CX2 of the second swing gear 720 and the center axis CX1 of the first swing gear 710 can rotate around the rotation center axis RCX of the gear frame 600 at different phases from each other, or can rotate around the rotation center axis RCX of the gear frame 600 at substantially the same phase. In addition, the first swing gear 710 and the second swing gear 720 contact the three shaft portions 612 of the gear frame 600 to rotate the gear frame 600 around the rotation center axis RCX. Therefore, the first swing gear 710 and the second swing gear 720 rotate and move in the housing 510 while meshing with the internal tooth pin 520.

[0043] The reduction ratio of the illustrated eccentric oscillating speed reducer 110 is determined by a first reduction ratio determined by the spur gear 810 and the fourth gear (center gear) 220 and a second reduction ratio determined by the internal gear ring and the gear portion 700. In the illustrated embodiment, the first reduction ratio may be smaller than the second reduction ratio.

[0044] Then, while Figure 5 and Figure 6 The effects of the gear unit 100 according to one embodiment of the present invention will be described by comparing with the conventional gear unit 100′ shown in FIG. Figure 5 and Figure 6 As shown, in the case of the conventional gear unit 100′, the input gear 1′ receives input from the driving source (motor) and transmits torque from the input gear 1′ to the center gear 3′ via the idler gear 2′. Thereafter, the input from the driving source is transmitted from the center gear 3′ to the speed reducer 120′ via the spur gears 4′, 5′, and 6′. However, in the structure of the gear unit 100′, the input from the input gear 1′ is transmitted to the center gear 3′ only via the idler gear 2′, so the load is concentrated on the position where the input gear 1′ meshes with the idler gear 2′ and the position where the idler gear 2′ meshes with the center gear 3′. Therefore, from the viewpoint of durability, it is necessary to increase the tooth width of the gears included in the gear unit 100′, and as a result, it is difficult to achieve miniaturization of the size of the speed reducer 120′ in the direction of the tooth width.

[0045] In contrast, a gear unit 100 according to an embodiment of the present invention includes a first gear (input gear) 1, a second gear (idler gear) 2 meshing with the first gear 1, a third gear (idler gear) 3 meshing with the first gear 1, and a fourth gear (center gear) 4 meshing with the second gear 2 and the third gear 3. That is, in the case of the gear unit 100 according to an embodiment of the present invention, the torque from the first gear (input gear) 1 is transmitted to the fourth gear 4 via the second gear 2 and the third gear 3. The power from the first gear 1 is dispersed to the second gear 2 and the third gear 3 and then transmitted to the fourth gear 4, so that the load can be suppressed from being concentrated on one part of the fourth gear 4. Therefore, the tooth width of the gear included in the gear unit 100 can be reduced. In addition, the size of the speed reducer 120 in the direction of the tooth width can be miniaturized.

[0046] Next, refer to Figure 7 A gear unit 100A according to another embodiment of the present invention will be described. Figure 7 As shown, a gear unit 100A according to another embodiment of the present invention includes, like the gear unit 100, a first gear (input gear) 1A connected to a driving source (motor), a second gear (idler gear) 2A meshing with the first gear 1A, a fourth gear (center gear) 4A, and a gear group 10A. The gear group 10A includes a fifth gear (spur gear) 5A, a sixth gear (spur gear) 6A, and a seventh gear (spur gear) 7A. The gear unit 100A according to another embodiment of the present invention does not have a third gear, and the first gear (input gear) 1A meshes with the second gear (idler gear) 2A and the seventh gear (spur gear) 7A, which is different from the gear unit 100. That is, the seventh gear 7A of the gear unit 100A is equivalent to a gear having the functions of both the third gear 3 and the seventh gear 7 of the gear unit 100.

[0047] In the gear unit 100A, the power from the first gear 1 is also distributed to the second gear 2 and the seventh gear 7 and then transmitted to the fourth gear 4, so it is possible to suppress the load from being concentrated on one part of the fourth gear 4. Therefore, the tooth width of the gear included in the gear unit 100A can be reduced. In addition, the size of the speed reducer in the direction of the tooth width can be miniaturized.

[0048] The above is a description of an exemplary embodiment of the present invention. The above embodiments are not limited to those described above, and can be applied to various transmission devices including reducers. Some of the features described in association with one embodiment of the above embodiments can also be applied to a transmission device described in association with another embodiment.

Claims

1. A speed reducer, comprising a gear unit, a speed reduction part and a gear frame, wherein the speed reduction part is used to reduce the speed of input from the gear unit and output the speed of input from the gear unit, wherein the speed reducer is characterized in that: The gear unit comprises: A first gear connected to a driving source; a second gear meshing with the first gear; a third gear meshing with the first gear; a fourth gear meshing with the second gear and the third gear; as well as The fifth gear meshes with the fourth gear. The speed reduction unit includes a crankshaft supported by the gear carrier and mounted on the fifth gear. The gear carrier has a first gear carrier member and a second gear carrier member, the second gear carrier member being opposed to the first gear carrier member in the direction of the rotation axis of the gear carrier. The second gear carrier member has a first end face facing the first gear carrier member and a second end face located on the opposite side to the first end face in the rotation axis direction. The fifth gear is arranged on the second end surface of the second gear carrier member.

2. The reducer according to claim 1, wherein: The fourth gear has a hole at its center portion. The diameter of the fourth gear is larger than the diameter of the second gear and the diameter of the third gear.

3. The reducer according to claim 1 or 2, wherein: The speed reducer has a support portion for supporting the fourth gear so as to be rotatable. In the rotation axis direction of the fourth gear, the end surface position of the support portion is substantially the same as the end surface position of the fourth gear.

4. The reducer according to claim 1 or 2, wherein: The fourth gear meshes with a gear set including a plurality of gears. The second gear and the third gear are arranged between two gears in the gear set in the circumferential direction of the fourth gear.

5. The reducer according to claim 1 or 2, wherein: The second gear, the third gear, and the fourth gear are arranged on the second end surface of the second gear carrier member.

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