Rotating device

Abstract

The invention provides a rotating device. This rotating device is provided with: a cylindrical housing (2); a carrier which is rotatably supported on the inner peripheral surface (2b) of the housing by means of a first bearing and a second bearing (16) and in which a first pin insertion hole and a second pin insertion hole (25b) are formed along the rotation axis; power transmission pins (9) which are inserted into the pin insertion holes of the carrier and which are supported by the carrier; a first bush and a second bush (72) which are fitted to the outer peripheral surface (9a) of the power transmission pin and which are arranged so as to be aligned with the first bearing and the second bearing along the rotational axis; and a first oscillating gear and a second oscillating gear (12) that engage with the power transmission pin via the first bush and the second bush, and transmit rotational force to each other between the first oscillating gear and the carrier via the power transmission pin. An outer end surface (72a) of each bush facing the first bearing or the second bearing is in contact only with the first bearing or the second bearing.

Description

Technical Field

[0001] The present invention relates to a rotating device. Background Art

[0002] As a rotating device, there is a known transmission that inputs rotation from an electric motor or the like to an input portion, decelerates or speeds up the rotation, and outputs it from an output portion. Also, as a transmission, there is a known eccentric oscillating type speed reducer that has high rotation position accuracy and load resistance.

[0003] Such a reducer, for example, includes: a housing (frame) having an internal gear formed on the inner circumferential surface; a swing gear (external gear) that meshes with the internal gear and swings and rotates; a crankshaft (input rotating body) having an eccentric portion that supports the swing gear so that it can rotate freely and transmits rotational force to the swing gear; a pin (gear carrier pin) to which the rotational force of the swing gear is transmitted; and a gear carrier (output rotating body) connected to the pin.

[0004] The crankshaft is rotatably supported on the gear frame by means of bearings. The gear frame is rotatably supported on the housing by means of bearings. Pin insertion holes for inserting or pressing pins are formed in the gear frame. Pin insertion holes for inserting pins are also formed in the swing gear. By inserting pins into these pin insertion holes, the rotation of the swing gear is transmitted to the gear frame by means of the pins.

[0005] The pin insertion hole of the swing gear is formed to a size that allows the swing gear to swing relative to the pin. A cylindrical bushing is fitted on the outer peripheral surface of the pin. The bushing is arranged at a portion of the outer peripheral surface of the pin that is inserted into the pin insertion hole. Thus, the bushing is in sliding contact with the pin and the swing gear, and the contact resistance is minimized. Thus, the driving efficiency is improved.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2017-82993 Summary of the invention

[0009] Problem that the invention aims to solve

[0010] However, in the above-mentioned prior art, the axial end surface of the bushing slides relative to the bearing and the carrier, so the contact resistance increases. Therefore, there is a problem that it is difficult to improve the driving efficiency of the speed reducer.

[0011] The present invention provides a rotating device capable of reliably improving driving efficiency.

[0012] Solutions for solving problems

[0013] A rotating device according to one aspect of the present invention comprises: a cylindrical first member; a second member rotatably supported on the inner peripheral surface of the first member by means of a bearing, and having a pin insertion hole formed along the rotation axis; a pin inserted into the pin insertion hole of the second member and supported by the second member; a bushing fitted on the outer peripheral surface of the pin and arranged along the rotation axis with the bearing; and a third member engaged with the pin by means of the bushing, and a rotational force is mutually transmitted between the third member and the second member by means of the pin. The end surface of the bushing facing the bearing side contacts only the bearing.

[0014] By configuring in this way, it is possible to prevent the bushing from contacting the second member in addition to the bearing. As a result, the contact area at the end surface of the bushing facing the bearing side can be made smaller than when the bushing contacts the bearing and the second member. As a result, the contact resistance caused by the bushing can be reduced, and the driving efficiency of the rotating device can be reliably improved.

[0015] In the above structure, the bearing may be arranged to protrude toward the bushing relative to the end surface of the second member facing the bushing. The radial wall thickness of the bushing may be greater than the radial distance between the outer peripheral surface of the pin and the inner peripheral surface of the bearing.

[0016] In the above structure, the hardness of the bearing may be the same as the hardness of the bushing.

[0017] Another aspect of the present invention is a rotating device comprising: a cylindrical internal gear provided with internal teeth; a gear frame supported on the inner peripheral surface of the internal gear in a rotatable manner by means of a first bearing, and provided with a first pin insertion hole along the rotation axis; a crankshaft supported on the gear frame in a rotatable manner by means of a second bearing and having an eccentric portion; a swing gear supported on the eccentric portion of the crankshaft in a rotatable manner, and provided with a second pin insertion hole along the rotation axis, and having external teeth meshing with the internal teeth; a pin inserted into the first pin insertion hole and the second pin insertion hole; and a bushing fitted on the outer peripheral surface of the pin and arranged at a portion inserted into the second pin insertion hole. The first bearing and the second bearing are arranged in a radial direction. The first pin insertion hole and the second pin insertion hole are arranged opposite to each other along the rotation axis. The bushing is arranged in a manner arranged along the rotation axis with the first bearing and the second bearing. An end surface of the bushing that faces the first bearing and the second bearing is in contact with only at least one of the first bearing and the second bearing.

[0018] Thus, in a so-called eccentric swing type speed reduction mechanism having a crankshaft and a swing gear, it is possible to prevent the bushing from contacting the gear carrier in addition to the first bearing and the second bearing. As a result, the contact area at the end surface of the bushing facing each bearing side can be made smaller than when the bushing contacts the gear carrier and each bearing. As a result, the contact resistance caused by the bushing can be reduced, and the driving efficiency of the rotating device can be reliably improved.

[0019] In the above structure, the first bearing may be arranged to protrude toward the bushing relative to the end surface of the gear frame that faces the bushing. The radial wall thickness of the bushing may be greater than the radial distance between the outer peripheral surface of the pin and the inner peripheral surface of the first bearing.

[0020] In the above structure, the second bearing may be arranged to protrude toward the bushing relative to the end surface of the gear frame that faces the bushing. The radial wall thickness of the bushing may be greater than the radial distance between the outer peripheral surface of the pin and the outer peripheral surface of the second bearing.

[0021] In the above configuration, the hardness of the first bearing, the hardness of the second bearing, and the hardness of the bushing may be the same.

[0022] Effects of the Invention

[0023] According to the above-described rotating device, the contact resistance caused by the bushing can be reduced, and therefore the driving efficiency can be reliably improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a cross-sectional view of a speed reducer according to an embodiment of the present invention.

[0025] Figure 2 yes Figure 1 Enlarged view of Part II.

[0026] Figure 3 It is a partially enlarged view of a speed reducer according to a modified example of the embodiment of the present invention.

[0027] Description of Reference Numerals

[0028] O, axis of rotation; 1, reducer (rotating device); 2, housing (internal gear, first component); 2b, inner circumferential surface of housing; 6, internal gear pin (internal gear); 7, gear rack (second component); 8, crankshaft; 9, power transmission pin (pin); 9a, outer circumferential surface of power transmission pin; 11, first swing gear (third component); 12, second swing gear (third component); 13, first flange (second component); 13c, inner end surface of first flange; 14, second flange (second component); 14e, inner end surface of second flange; 15, first bearing (bearing, first bearing); 16, second bearing (bearing, first bearing); 18, inner ring; 18b, inner end surface of inner ring; 18c, inner circumferential surface of inner ring; 21a, first eccentric portion (eccentric portion); 21b, the second eccentric portion (eccentric portion); 23a, the outer teeth of the first swing gear; 23b, the outer teeth of the second swing gear; 25a, the first pin insertion hole (the second pin insertion hole); 25b, the second pin insertion hole (the second pin insertion hole); 33, the third bearing (the second bearing); 34, the fourth bearing (the second bearing); 41, the outer ring; 41b, the inner end face of the outer ring; 41c, the outer peripheral surface of the outer ring; 51, the first bolt insertion hole (pin insertion hole, the first pin insertion hole); 52, the second bolt insertion hole (pin insertion hole, the first pin insertion hole); 71, the first bushing (bushing); 71a, the outer end face (end face) of the first bushing; 72, the second bushing (bushing); 72a, the outer end face (end face) of the second bushing; T3, wall thickness; T4, T5, distance. DETAILED DESCRIPTION

[0029] Next, embodiments of the present invention will be described based on the drawings.

[0030] <Reduction gear>

[0031] Figure 1 It is a cross-sectional view of the speed reducer 1 .

[0032] The speed reducer 1 as a rotating device is a so-called eccentric oscillating speed reducer and includes a cylindrical housing 2 and a gear carrier 7 rotatably supported on the housing 2 via two bearings 15 and 16 (a first bearing 15 and a second bearing 16 ).

[0033] The housing 2 is an example of the internal gear and the first member in the claims. The two bearings 15 and 16 (the first bearing 15 and the second bearing 16) are an example of the bearing and the first bearing in the claims. The gear carrier 7 is an example of the second member in the claims.

[0034] Hereinafter, the axial direction of the housing 2 is simply defined as the axial direction. The circumferential direction of the housing 2 is simply defined as the circumferential direction. The radial direction of the housing 2 is simply defined as the radial direction. Regarding the axial direction, there is a case where the axial center side of the housing 2 is referred to as the axial inner side, and the side opposite to the axial inner side is referred to as the axial outer side.

[0035] <Housing>

[0036] The housing 2 is formed of, for example, an iron-based material such as cast iron. In addition, the housing 2 may also be formed of, for example, an aluminum alloy, a magnesium alloy, a carbon fiber reinforced plastic (CFRP), a resin containing boron nitride to improve thermal conductivity, or the like. A plurality of bolt holes 2a are formed on the outer periphery of the housing 2 at equal intervals in the circumferential direction and penetrate in the axial direction. By inserting a bolt (not shown) into the bolt hole 2a and fastening the bolt to the external device, the reducer 1 is fixed to the external device.

[0037] Bearing housings 3 and 4 (first bearing housing 3 and second bearing housing 4) are formed on both axial sides of the inner peripheral surface 2b of the housing 2. The inner diameters of the bearing housings 3 and 4 are enlarged relative to the inner diameter of the inner peripheral surface 2b of the housing 2 by step portions 3a and 4a.

[0038] A seal housing 5 is formed at a portion of the inner peripheral surface 2b of the housing 2 that is located axially outward from the second bearing housing 4. The seal housing 5 is formed so that the inner diameter becomes larger than the inner diameter of the second bearing housing 4 by means of a step portion 5a. A seal 40 is fitted into the seal housing 5. The seal 40 seals between the housing 2 and the gear carrier 7.

[0039] A plurality of internal tooth pins (an example of internal teeth in the claims) 6 are provided on the portion of the inner circumferential surface 2b of the housing 2 between the two bearing housings 3 and 4. The internal tooth pins 6 are formed into a cylindrical shape extending in the axial direction. However, this is not limited to this, and the internal tooth pins 6 may also be hollow components. The internal tooth pins 6 are arranged at equal intervals in the circumferential direction. The internal tooth pins 6 function as a part of the speed reduction mechanism 30. That is, the internal tooth pins 6 function as internal teeth that mesh with the swing gears 11 and 12 discussed later.

[0040] The first bearing 15 is fitted into the first bearing housing 3 of the housing 2 thus constructed. The second bearing 16 is fitted into the second bearing housing 4. The first bearing 15 and the second bearing 16 have the same structure, so only the second bearing 16 will be described in the following description. The description of the first bearing 15 is marked with the same reference numerals as those of the second bearing 16, and the description is omitted.

[0041] The second bearing 16 is formed of, for example, high-carbon chromium bearing steel such as SUJ2. The second bearing 16 is a ball bearing. More specifically, the second bearing 16 is, for example, an angular contact ball bearing.

[0042] The second bearing 16 includes: an annular outer ring 17; an annular inner ring 18, which is arranged radially inward of the outer ring 17; and a rolling element 19, which is arranged between the outer ring 17 and the inner ring 18. The outer ring 17 is fitted with the second bearing housing 4. The inner end surface 17a of the outer ring 17 abuts against the step portion 4a of the second bearing housing 4. The inner end surface 17a is a surface located in the axial inner side of the outer ring 17 and facing the axial inner side. Thus, the second bearing 16 is positioned relative to the housing 2.

[0043] <Reduction Mechanism>

[0044] The speed reduction mechanism 30 includes: a gear frame 7; a power transmission pin 9, which is arranged on the gear frame 7; a crankshaft 8, which is supported on the gear frame 7 in a rotatable manner by means of two bearings 33, 34 (third bearing 33, fourth bearing 34); and two swing gears 11, 12 (first swing gear 11, second swing gear 12), which are supported on the crankshaft 8 in a rotatable manner.

[0045] In addition, the power transmission pin 9 is an example of a pin in the claims. The two bearings 33 and 34 (the third bearing 33 and the fourth bearing 34) are an example of a second bearing in the claims. The two swing gears 11 and 12 (the first swing gear 11 and the second swing gear 12) are an example of a third member in the claims.

[0046] The rotation axis O of the gear carrier 7 coincides with the rotation axis of the crankshaft 8 . These rotation axes coincide with the central axis of the housing 2 .

[0047] The gear carrier 7 is composed of a disc-shaped first flange 13 and a second flange 14 disposed on both sides in the axial direction. The first flange 13 and the second flange 14 are formed of an iron-based material such as cast iron.

[0048] Of the two flanges 13 and 14, the second flange 14 is disposed on the sealed housing 5 side of the housing 2. The outer peripheral surface of the second flange 14 fits with the inner ring 18 of the second bearing 16. The outer peripheral surface of the first flange 13 fits with the inner ring 18 of the first bearing 15.

[0049] The first flange 13 is formed so that the thickness in the axial direction is uniform as a whole. The outer end surface 13b and the inner end surface 13c of the first flange 13 are respectively formed flat and arranged parallel to each other.

[0050] The outer end surface 13b is a surface located on the axially outer side and facing the axially outer side of the first flange 13. The inner end surface 13c is a surface located on the axially inner side and facing the axially inner side of the first flange 13.

[0051] A first opening 13a that axially penetrates the first flange 13 is formed in a portion located in the radial center of the first flange 13. A third bearing housing 35 is formed in the first opening 13a.

[0052] The first flange 13 has a plurality of first bolt insertion holes (pin insertion holes in the claims, an example of first pin insertion holes) 51 formed between the outer peripheral surface and the third bearing housing 35. The first bolt insertion holes 51 penetrate the first flange 13 in the axial direction. The first bolt insertion holes 51 are arranged at equal intervals in the circumferential direction.

[0053] The second flange 14 is formed so that the thickness in the axial direction is uniform as a whole. The outer end surface 14d and the inner end surface 14e of the second flange 14 are respectively formed flat and arranged parallel to each other.

[0054] The outer end surface 14d is a surface located on the axially outer side and facing the axially outer side of the second flange 14. The inner end surface 14e is a surface located on the axially inner side and facing the axially inner side of the second flange 14.

[0055] Part of the outer peripheral surface of the second flange 14 radially faces the seal housing 5 of the housing 2. A seal 40 is fitted to the part of the outer peripheral surface of the second flange 14 facing the seal housing 5. Thus, the housing 2 and the second flange 14 constituting the gear carrier 7 are sealed.

[0056] An outer peripheral bearing housing 14a is formed on the axially inner portion of the outer peripheral surface of the second flange 14. The outer peripheral bearing housing 14a is formed in such a manner that the outer diameter becomes smaller than the outer diameter of the second flange 14 by means of the step portion 14b. The inner ring 18 of the second bearing 16 is fitted into the outer peripheral bearing housing 14a. The outer end surface 18a of the inner ring 18 abuts against the step portion 14b. The outer end surface 18a is a surface located on the axially outer side of the inner ring 18 and facing the axially outer side. Thus, the second bearing 16 is positioned relative to the second flange 14.

[0057] A second opening 14c is formed in the radially central portion of the second flange 14, which penetrates the second flange 14 in the axial direction. A fourth bearing housing 36 is formed in the axially inner portion of the inner peripheral surface of the second opening 14c. The fourth bearing housing 36 is formed in such a manner that the inner diameter becomes larger than the inner diameter of the second opening 14c by means of a step portion 36a. The fourth bearing housing 36 is arranged in a radially aligned manner with the outer peripheral bearing housing 14a and the second bearing housing 4.

[0058] In the second flange 14 , a plurality of second bolt insertion holes (pin insertion holes in the claims, an example of first pin insertion holes) 52 are formed between the outer peripheral bearing housing 14 a and the fourth bearing housing 36 .

[0059] The second bolt insertion hole 52 penetrates the second flange 14 in the axial direction. The plurality of second bolt insertion holes 52 are arranged at equal intervals in the circumferential direction and are arranged coaxially with the first bolt insertion hole 51. The inner diameter of the second bolt insertion hole 52 is the same as the inner diameter of the first bolt insertion hole 51. A countersink portion 52a is formed in the axially outer portion of the second bolt insertion hole 52. The countersink portion 52a is formed in such a manner that the inner diameter becomes larger than the inner diameter of the second bolt insertion hole 52 by means of a step portion 52b.

[0060] In the gear frame 7 thus constructed, the third bearing 33 is fitted into the third bearing housing 35 of the first flange 13. The fourth bearing 34 is fitted into the fourth bearing housing 36 of the second flange 14. The third bearing 33 and the fourth bearing 34 have the same structure, and therefore, in the following description, only the fourth bearing 34 is described, and the description of the third bearing 33 is omitted by marking the same reference numeral as the reference numeral of the fourth bearing 34.

[0061] The fourth bearing 34 is formed of, for example, high-carbon chromium bearing steel such as SUJ2. The fourth bearing 34 is a ball bearing. More specifically, the fourth bearing 34 is, for example, a deep groove ball bearing.

[0062] The fourth bearing 34 includes: an annular outer ring 41; an annular inner ring 42, which is arranged radially inward of the outer ring 41; and rolling elements 43, which are arranged between the outer ring 41 and the inner ring 42. The outer ring 41 is fitted with the fourth bearing housing 36. The outer end surface 41a of the outer ring 41 abuts against the step portion 36a of the fourth bearing housing 36. The outer end surface 41a is a surface located in the axial outer side and facing the axial outer side of the outer ring 41. Thus, the fourth bearing 34 is positioned relative to the second flange 14.

[0063] The power transmission pin 9 is inserted into each of the bolt insertion holes 51 and 52 of each of the flanges 13 and 14. The power transmission pin 9 is formed of, for example, aluminum-chromium-molybdenum steel.

[0064] The power transmission pin 9 includes: a cylindrical shaft portion 61; an external thread portion 62, which is integrally formed with the shaft portion 61; and a head portion 63, which is integrally formed with the shaft portion 61. The external thread portion 62 is formed at one end of the shaft portion 61 along the axial direction. The head portion 63 is formed at the other end of the shaft portion 61 along the axial direction. The shaft portion 61, the external thread portion 62, and the head portion 63 are arranged on the same axis. In addition, Figure 1 In FIG. 6 , the thread of the external thread portion 62 is omitted from illustration.

[0065] The outer diameter of the shaft portion 61 is the same as or slightly smaller than the inner diameter of the first bolt insertion hole 51 and the inner diameter of the second bolt insertion hole 52. The outer thread portion 62 is formed so that the outer diameter becomes smaller than the outer diameter of the shaft portion 61 by means of the thread step portion 62a. The head portion 63 is formed so that the outer diameter becomes larger than the outer diameter of the shaft portion 61 by means of the head step portion 63a. The outer diameter of the head portion 63 is slightly smaller than the outer diameter of the counterbore portion 52a of the second flange 14.

[0066] Based on such a structure, the power transmission pin 9 is inserted from the second flange 14 side with the external thread portion 62 toward the first flange 13 side in the order of the second bolt insertion hole 52 and the first bolt insertion hole 51. At this time, the head portion 63 of the power transmission pin 9 is inserted into the countersunk portion 52a of the second bolt insertion hole 52. The power transmission pin 9 is positioned axially relative to the second flange 14 by the head step portion 63a of the power transmission pin 9 abutting against the step portion 52b of the second bolt insertion hole 52.

[0067] On the other hand, the external thread portion 62 of the power transmission pin 9 protrudes axially outward through the first bolt insertion hole 51. The flat washer 65 is fitted over the external thread portion 62. The nut 66 is fastened to the external thread portion 62 from the flat washer 65. Thus, the power transmission pin 9 is fixed to the gear frame 7 (the first flange 13, the second flange 14).

[0068] A first annular spacer 64a is provided between the inner ring 18 of the first bearing 15 and the flat washer 65. A second annular spacer 64b is provided between the outer ring 41 of the third bearing 33 and the flat washer 65. The thickness T1 of the first spacer 64a is thicker than the thickness T2 of the second spacer 64b. The thicknesses T1 and T2 are described in more detail below.

[0069] The thickness T1 of the first spacer 64a is set to a thickness that the inner end surface 18b of the inner ring 18 of the first bearing 15 slightly protrudes toward the axial inner side relative to the inner end surface 13c of the first flange 13. The inner end surface 18b is a surface located axially inside and facing axially inside in the inner ring 18. Hereinafter, the condition that satisfies such a state of the first bearing 15 is defined as a first bearing condition.

[0070] The thickness T2 of the second spacer 64b is set to a thickness such that the inner end surface 41b of the outer ring 41 of the third bearing 33 is slightly sunken (depressed) toward the axial outer side relative to the inner end surface 13c of the first flange 13. The inner end surface 41b is a surface located axially inside and facing axially inside in the outer ring 41. Hereinafter, the condition that satisfies such a state of the third bearing 33 is defined as the third bearing condition.

[0071] In the state where the power transmission pin 9 is fixed, two bushings 71 and 72 (first bushing 71 and second bushing 72) are fitted in the portion of the shaft portion 61 between the first flange 13 and the second flange 14. The two bushings 71 and 72 (first bushing 71 and second bushing 72) are an example of bushings in the claims. The bushings 71 and 72 are formed of high carbon chromium bearing steel such as SUJ2, for example. That is, the hardness of the bushings 71 and 72 is the same as the hardness of the bearings 15, 16, 33, and 34.

[0072] The crankshaft 8 is rotatably supported by the flanges 13 and 14 via the third bearing 33 and the fourth bearing 34. The crankshaft 8 is formed of, for example, an aluminum alloy, similarly to the power transmission pin 9. In addition, as the crankshaft 8, similarly to the power transmission pin 9, for example, stainless steel or various iron-based metals can be used.

[0073] The crankshaft 8 is formed in a hollow shape. A first eccentric portion 21 a and a second eccentric portion 21 b are formed side by side in the axial direction on the outer peripheral surface of the crankshaft 8 . The first eccentric portion 21 a and the second eccentric portion 21 b are arranged between the third bearing 33 and the fourth bearing 34 .

[0074] The first eccentric portion 21a is arranged at a position closer to the first flange 13 than the second eccentric portion 21b. The second eccentric portion 21b is arranged at a position closer to the second flange 14 than the first eccentric portion 21a. Each eccentric portion 21a, 21b is arranged in an eccentric state relative to the rotation axis O of the crankshaft 8 (gear carrier 7). The phase angles of each eccentric portion 21a, 21b are deviated from each other. For example, the phase angles of each eccentric portion 21a, 21b are deviated from each other by 180°.

[0075] The eccentric portions 21a and 21b are provided with bearings 37 and 38 (fifth bearing 37 and sixth bearing 38), respectively. The bearings 37 and 38 are, for example, needle bearings.

[0076] The eccentric portions 21 a and 21 b support swing gears 11 and 12 (first swing gear 11 and second swing gear 12 ) rotatably via bearings 37 and 38 . Therefore, the swing gears 11 and 12 are disposed between the first flange 13 and the second flange 14 .

[0077] The two swing gears 11 and 12 are formed of an iron material such as chrome-molybdenum steel. The two swing gears 11 and 12 are formed with crankshaft insertion holes 24a and 24b (first crankshaft insertion hole 24a and second crankshaft insertion hole 24b) penetrating in the thickness direction. The crankshaft insertion holes 24a and 24b are formed in the radially central portion of the swing gears 11 and 12. Bearings 37 and 38 are respectively fitted in the crankshaft insertion holes 24a and 24b.

[0078] External teeth 23a, 23b meshing with the internal tooth pins 6 of the housing 2 are formed on the outer circumferences of the two swing gears 11, 12. The number of teeth of each external tooth 23a, 23b is less than the number of internal tooth pins 6, for example, one.

[0079] Pin insertion holes 25a, 25b (first pin insertion hole 25a, second pin insertion hole 25b) are formed at positions of the two swing gears 11, 12 corresponding to the power transmission pin 9. The pin insertion holes 25a, 25b (first pin insertion hole 25a, second pin insertion hole 25b) are an example of the second pin insertion hole in the claims.

[0080] The shaft portion 61 of the power transmission pin 9 is inserted into each of the pin insertion holes 25a and 25b. The first bushing 71 fitted with the shaft portion 61 is inserted into the first pin insertion hole 25a. The second bushing 72 fitted with the shaft portion 61 is inserted into the second pin insertion hole 25b.

[0081] Based on such a structure, each swing gear 11, 12 is set to be swingable and rotatable due to the eccentric parts 21a, 21b of the crankshaft 8. The inner diameter of each pin insertion hole 25a, 25b of each swing gear 11, 12 is set to a size that allows the swing rotation of each swing gear 11, 12 in a state where the shaft part 61 of the power transmission pin 9 and each bushing 71, 72 are inserted.

[0082] <Dimensional Relationships among the Second Flange, Second Bearing, Fourth Bearing, and Second Bushing>

[0083] Next, based on Figure 2 The dimensional relationship among the second flange 14 , the second bearing 16 , the fourth bearing 34 , and the second bushing 72 will be described.

[0084] Figure 2 yes Figure 1 Enlarged view of Part II.

[0085] like Figure 2 As shown, the axial length L1 of the outer peripheral bearing housing 14a is shorter than the axial length L2 of the inner ring 18 in the second bearing 16. Therefore, the inner end surface 18b of the inner ring 18 of the second bearing 16 protrudes toward the axial inner side relative to the inner end surface 14e of the outer peripheral bearing housing 14a (second flange 14). Hereinafter, the condition that satisfies such a state of the second bearing 16 is defined as the second bearing condition.

[0086] The axial length L3 of the fourth bearing housing 36 is longer than the axial length L4 of the outer ring 41 in the fourth bearing 34. Therefore, the inner end face 41b of the outer ring 41 in the fourth bearing 34 is offset so as to be sunken toward the axial outer side relative to the inner end face 14e of the fourth bearing housing 36 (second flange 14). Hereinafter, the condition satisfying such a state of the fourth bearing 34 is defined as the fourth bearing condition.

[0087] The radial wall thickness T3 of the second bushing 72 is greater than the radial distance T4 between the outer peripheral surface 9a of the power transmission pin 9 and the inner peripheral surface 18c of the inner ring 18 in the second bearing 16. Although not particularly shown in the figure, the radial wall thickness of the first bushing 71 is greater than the radial distance between the outer peripheral surface 9a of the power transmission pin 9 and the inner peripheral surface 18c of the inner ring 18 in the first bearing 15. Hereinafter, the condition satisfying such a dimension is defined as the outer diameter condition of the bushing.

[0088] Thus, by satisfying the second bearing condition and the bushing outer diameter condition, the outer end surface 72a of the second bushing 72 contacts only the inner end surface 18b of the inner ring 18 in the second bearing 16. The outer end surface 72a is a surface of the second bushing 72 located axially outward and facing axially outward.

[0089] In particular, the inner end surface 14e of the second flange 14 is formed flat. Therefore, even in the fourth bearing condition, the outer end surface 72a of the second bushing 72 and the fourth bearing housing 36 do not come into contact.

[0090] This also applies to the relationship between the first bearing 15 and the first bushing 71 and the relationship between the third bearing 33 and the first bushing 71. That is, by satisfying the first bearing condition and the bushing outer diameter condition, the outer end surface 71a (see Figure 1 ) contacts only the inner end surface 18b of the inner ring 18 in the first bearing 16. The outer end surface 71a is a surface located on the axial outer side of the first bushing 71 and facing the axial outer side.

[0091] In particular, the inner end surface 13 c of the first flange 13 is formed flat. Therefore, even in the third bearing condition, the outer end surface 71 a of the first bushing 71 and the first flange 13 do not come into contact.

[0092] <Operation of the speed reducer>

[0093] Next, the operation of the speed reducer 1 will be described.

[0094] When the crankshaft 8 is rotated by, for example, an electric motor (not shown), the swing gears 11 and 12 supported by the eccentric parts 21a and 21b in a rotatable manner swing and rotate. Then, a part of the external teeth 23a and 23b of the swing gears 11 and 12 meshes with the internal tooth pins 6 of the housing 2. At this time, the number of teeth of each external tooth 23a and 23b is less than the number of internal tooth pins 6, for example, one, so the meshing parts of each external tooth 23a and 23b are sequentially offset in the circumferential direction relative to the internal tooth pins 6 (housing 2), and each swing gear 11 and 12 rotates. This rotation is reduced in speed relative to the rotation of the crankshaft 8.

[0095] A power transmission pin 9 is inserted into the pin insertion holes 25a and 25b of each swing gear 11 and 12. Therefore, through the self-rotation of each swing gear 11 and 12, the rotational force of the self-rotation direction of the swing gear 11 and 12 is transmitted to each power transmission pin 9 via the bushings 71 and 72, respectively. That is, the bushings 71 and 72 slide together with the corresponding swing gears 11 and 12. Each power transmission pin 9 is fixed to the gear frame 7 (the first flange 13 and the second flange 14). Therefore, the rotational force of the swing gears 11 and 12 is transmitted to the gear frame 7 via each power transmission pin 9. The gear frame 7 is supported on the housing 2 in a rotatable manner via the first bearing 15 and the second bearing 16.

[0096] As a result, the carrier 7 rotates relative to the case 2 . That is, the rotation input to the crankshaft 8 is decelerated and output from the carrier 7 .

[0097] However, the bushings 71 and 72 may slightly move in the axial direction as the swing gears 11 and 12 are driven. In this case, the bushings 71 and 72 slide relative to the member existing outside the bushings 71 and 72 in the axial direction.

[0098] As described above, the outer end surface 72a of the second bushing 72 contacts only the inner end surface 18b of the inner ring 18 in the second bearing 16. Also, the outer end surface 72a of the second bushing 72 does not contact the fourth bearing housing 36. Similarly, the outer end surface 71a of the first bushing 71 (see Figure 1 ) contacts only the inner end surface 18b of the inner ring 18 in the first bearing 15. Furthermore, the outer end surface 71a of the first bushing 71 does not contact the first flange 13.

[0099] Therefore, the contact area of ​​the outer end surfaces 71 a , 72 a of the bushes 71 , 72 can be reduced compared to the case where the outer end surfaces 71 a , 72 a of the bushes 71 , 72 are in contact with both the corresponding bearings 15 , 16 and the flanges 13 , 14 .

[0100] Thus, in the above-mentioned embodiment, the outer end faces 71a and 72a of each bushing 71 and 72 are in contact only with the inner end faces 18b of the inner rings 18 in the corresponding bearings 15 and 16. Therefore, the contact area at the outer end faces 71a and 72a of each bushing 71 and 72 can be minimized. Therefore, the contact resistance caused by each bushing 71 and 72 can be reduced. As a result, the driving efficiency of the reducer 1 can be reliably improved.

[0101] Furthermore, the outer end face 72a of the second bushing 72 contacts only the inner end face 18b of the inner ring 18 in the second bearing 16, so a small gap G1 is formed between the outer end face 72a of the second bushing 72 and the inner end face 14e of the outer peripheral bearing housing 14a. Furthermore, the small gap G1 is formed by being surrounded by the outer end face 72a of the second bushing 72, the outer peripheral face 9a of the power transmission pin 9, the inner end face 14e of the outer peripheral bearing housing 14a, and the inner peripheral face 18c of the inner ring 18 in the second bearing 16.

[0102] Therefore, for example, lubricating oil can be actively retained in the small gap G1 . Therefore, the driving efficiency of the speed reducer 1 can be further improved. This also applies to the space between the outer end surface 71 a of the first bushing 71 and the first flange 13 .

[0103] By satisfying the second bearing condition and the outer diameter condition of the bushing, the outer end face 72a of the second bushing 72 can be reliably contacted only with the inner ring 18 of the second bearing 16. By satisfying the first bearing condition and the outer diameter condition of the bushing, the outer end face 71a of the first bushing 71 can be reliably contacted only with the inner ring 18 of the first bearing 16.

[0104] Furthermore, the hardness of each bushing 71 , 72 is the same as the hardness of each bearing 15 , 16 , 33 , 34 .

[0105] If the hardness of the first bearing 15 and the second bearing 16 is different from the hardness of the bushings 71 and 72, wear of the bearings 15 and 16 and the bushings 71 and 72 is accelerated. In this case, the driving efficiency of the speed reducer 1 may be reduced.

[0106] Therefore, by making the hardness of each bushing 71, 72 the same as the hardness of each bearing 15, 16, 33, 34, it is possible to suppress the acceleration of wear of any of the bearings 15, 16 and bushings 71, 72. As a result, the driving efficiency of the speed reducer 1 can be more reliably improved.

[0107] [Modifications]

[0108] The present invention is not limited to the above-described embodiment, and includes embodiments in which various modifications are added to the above-described embodiment within a scope not departing from the gist of the present invention.

[0109] For example, in the above-mentioned embodiment, the reducer 1 is described as a rotating device. However, it is not limited to this, and the structure of the above-mentioned reducer 1 can be adopted in various rotating devices. As a rotating device, it can be provided with the following components: a cylindrical first component taking the housing 2 as an example; a second component taking the gear frame 7 as an example, which is supported on the inner peripheral surface of the first component in a rotatable manner by means of a bearing; a pin, which is inserted into a pin insertion hole formed in the second component; a bushing, which is fitted on the outer peripheral surface of the pin; and a third component taking the swing gear 11, 12 as an example, which is engaged with the pin by means of a bushing, and the rotational force is transmitted to each other between it and the second component by means of the pin. The bushing and the bearing can be arranged in an axial direction.

[0110] In the above-mentioned embodiment, the speed reducer 1 having the speed reduction mechanism 30 for reducing the rotation of the crankshaft 8 and outputting the speed is described. However, this is not limited to this, and the above-mentioned power transmission pin 9 may be used in the speed increaser instead of the speed reduction mechanism 30. Furthermore, the above-mentioned power transmission pin 9 may be used in a rotating device provided with a component that replaces the speed reduction mechanism 30 (gear frame 7, swing gears 11, 12). A pin insertion hole (pin insertion holes 25a, 25b) for inserting the power transmission pin 9 may be formed in the component that replaces the speed reduction mechanism 30.

[0111] In the above-mentioned embodiment, the following case is described: the speed reduction mechanism 30 includes one crankshaft 8, and the rotation axis O of the gear frame 7 coincides with the rotation axis O of the crankshaft 8. However, the speed reduction mechanism 30 is not limited to this, and the speed reduction mechanism 30 may be a so-called eccentric swing type speed reduction mechanism that swings and rotates the two swing gears 11 and 12. For example, three crankshafts 8 may be provided and arranged around the rotation axis O of the gear frame 7. The two swing gears 11 and 12 may also be swing-rotated by using these crankshafts 8.

[0112] In the above-mentioned embodiment, the case where the bushings 71 and 72 are formed of the same material as the materials of the bearings 15, 16, 33, and 34 is described. Thus, the case where the hardness of the bushings 71 and 72 is the same as the hardness of the bearings 15, 16, 33, and 34 is described. However, this is not limited to this, and the bushings 71 and 72 may not be formed of the same material as the materials of the bearings 15, 16, 33, and 34. The hardness of the bushings 71 and 72 does not need to be exactly the same as the hardness of the bearings 15, 16, 33, and 34, but it only needs to be the same degree. In this specification, the meaning of the hardness of the bushings 71 and 72 being the same as the hardness of the bearings 15, 16, 33, and 34 also includes the meaning of the same degree. The same degree is set, for example, the absolute value of the difference in Rockwell hardness is less than 6HRC.

[0113] In the above-mentioned embodiment, the following case is described: the outer end surface 71a of each bushing 71, 72 is in contact only with the inner end surface 18b of the inner ring 18 in the corresponding first bearing 15 and second bearing 16. However, this is not limited to this, and the outer end surface 71a of each bushing 71, 72 only needs to be in contact with each bearing 15, 16, 33, 34. In other words, the outer end surface 71a of each bushing 71, 72 does not need to be in contact with the gear frame 7 (first flange 13, second flange 14).

[0114] based on Figure 3 A specific example of this case will be described.

[0115] Figure 3 It is a partially enlarged view of the speed reducer 1 in a modified example. Figure 3 and Figure 2 Corresponding.

[0116] like Figure 3 As shown, the outer end surface 71a of each bushing 71, 72 may be in contact with only the inner end surface 41b of the outer ring 41 of the corresponding third bearing 33 and fourth bearing 34. The dimensional relationship of each part in such a case will be described below.

[0117] <Dimensional Relationships among Second Flange, Second Bearing, Fourth Bearing, and Second Bushing in Modification>

[0118] The axial length L1' of the outer bearing housing 14a is equal to or slightly longer than the axial length L2' of the inner ring 18 in the second bearing 16. In the example shown in the figure, the length L1' and the length L2' are equal. Therefore, the inner end face 18b of the second bearing 16 and the inner end face 14e of the outer bearing housing 14a (second flange 14) are arranged on the same plane (refer to Figure 3 ). In addition, the inner end face 18b of the second bearing 16 may be offset in a manner that is sunken toward the axial inside relative to the inner end face 14e of the outer peripheral bearing housing 14a (second flange 14). Hereinafter, the condition that satisfies such a state of the second bearing 16 is defined as the second bearing condition of the modified example.

[0119] The axial length L3' of the fourth bearing housing 36 is shorter than the axial length L4' of the outer ring 41 in the fourth bearing 34. Therefore, the inner end surface 41b of the outer ring 41 in the fourth bearing 34 protrudes toward the axial inner side relative to the inner end surface 14e of the fourth bearing housing 36 (second flange 14). Hereinafter, the condition that satisfies such a state of the fourth bearing 34 is defined as the fourth bearing condition of the modified example.

[0120] The radial wall thickness T3 of the second bushing 72 is greater than the radial distance T5 between the outer peripheral surface 9a of the power transmission pin 9 and the outer peripheral surface 41c of the outer ring 41 in the fourth bearing 34. Although not particularly shown in the figure, the radial wall thickness of the first bushing 71 is greater than the radial distance between the outer peripheral surface 9a of the power transmission pin 9 and the outer peripheral surface 41c of the outer ring 41 in the third bearing 33. Hereinafter, the condition satisfying such a dimension is defined as the outer diameter condition of the bushing of the modified example.

[0121] In this way, by satisfying the second bearing condition of the modified example, the fourth bearing condition, and the outer diameter condition of the bushing of the modified example, the outer end face 72a of the second bushing 72 contacts only the inner end face 41b of the outer ring 41 in the fourth bearing 34. In particular, the inner end face 14e of the second flange 14 is formed flat. Therefore, even if the second bearing condition of the modified example is met, the outer end face 72a of the second bushing 72 does not contact the outer peripheral bearing housing 14a.

[0122] Even when the length L1 ′ is slightly longer than the length L2 ′, the outer end surface 72 a of the second bushing 72 only needs to contact the inner end surface 41 b of the outer ring 41 of the fourth bearing 34 .

[0123] The same conditions as described above can also be adopted for the conditions of the first bearing 15 and the first bushing 71, and the conditions of the third bearing 33 and the first bushing 71. Thus, the outer end surface 71a of the first bushing 71 can be brought into contact only with the inner end surface 41b of the outer ring 41 in the third bearing 33. Therefore, according to this modified example, the same effects as those of the aforementioned embodiment are achieved.

[0124] In this modified example, a small gap G2 is formed between the outer end face 72a of the second bushing 72 and the inner end face 14e of the fourth bearing housing 36. The small gap G2 is formed by being surrounded by the outer end face 72a of the second bushing 72, the outer peripheral face 9a of the power transmission pin 9, the inner end face 14e of the fourth bearing housing 36, and the outer peripheral face 41c of the outer ring 41 in the fourth bearing 34. Therefore, for example, lubricating oil can also be actively retained in the small gap G2. This is also the case between the outer end face 71a of the first bushing 71 and the first flange 13.

[0125] Furthermore, the outer end surface 71a of the first bushing 71 may be in contact with both the inner ring 18 of the first bearing 15 and the outer ring 41 of the third bearing 33. The outer end surface 72a of the second bushing 72 may be in contact with both the inner ring 18 of the second bearing 16 and the outer ring 41 of the fourth bearing 34. Even in such a configuration, the contact area at the outer end surface 71a of each bushing 71, 72 can be reduced compared to the case where the outer end surface 71a of each bushing 71, 72 is in contact with both the corresponding bearings 15, 16 and the flanges 13, 14.

[0126] In the embodiments disclosed in this specification, a component composed of multiple objects may be integrated into one, or a component composed of one object may be divided into multiple objects. Regardless of whether the components are integrated or not, they may be configured in a manner that can achieve the purpose of the invention.

Claims

1. A rotating device, wherein: The rotating device has: A first cylindrical member; a second member rotatably supported on the inner peripheral surface of the first member by a bearing and having a pin insertion hole formed along the rotation axis; a pin inserted into the pin insertion hole of the second member and supported by the second member; a bushing fitted on the outer peripheral surface of the pin and arranged along the rotation axis with the bearing; as well as a third member that engages with the pin via the bushing, and mutually transmits rotational force between the third member and the second member via the pin; The end surface of the bushing that faces the bearing is in contact only with the bearing.

2. The rotating device according to claim 1, wherein: The bearing is arranged so as to protrude toward the bushing with respect to the end surface of the second member that faces the bushing. A radial wall thickness of the bushing is greater than a radial distance between the outer peripheral surface of the pin and an inner peripheral surface of the bearing.

3. The rotating device according to claim 1 or 2, wherein: The hardness of the bearing is the same as the hardness of the bushing.

4. A rotating device comprising: a cylindrical internal gear provided with internal teeth; a gear carrier rotatably supported on the inner peripheral surface of the internal gear by means of a first bearing and provided with a first pin insertion hole along the rotation axis; a crankshaft rotatably supported on the gear carrier by a second bearing and having an eccentric portion; a swing gear rotatably supported on the eccentric portion of the crankshaft, provided with a second pin insertion hole along the rotation axis and having external teeth meshing with the internal teeth; a pin inserted into the first pin insertion hole and the second pin insertion hole; as well as a bushing which is fitted on the outer peripheral surface of the pin and is arranged at a portion inserted into the second pin insertion hole, The first bearing and the second bearing are arranged in a radial direction. The first pin insertion hole and the second pin insertion hole are arranged opposite to each other along the rotation axis. The bushing is arranged in a manner aligned with the first bearing and the second bearing along the rotation axis. An end surface of the bushing that faces the first bearing and the second bearing is in contact with only at least one of the first bearing and the second bearing.

5. The rotating device according to claim 4, wherein: The first bearing is arranged so as to protrude toward the bushing with respect to the end surface of the gear carrier that faces the bushing. A radial wall thickness of the bushing is greater than a radial distance between the outer peripheral surface of the pin and an inner peripheral surface of the first bearing.

6. The rotating device according to claim 4 or 5, wherein: The second bearing is arranged so as to protrude toward the bushing side relative to the end surface of the gear carrier that faces the bushing side. A radial wall thickness of the bushing is greater than a radial distance between the outer peripheral surface of the pin and an outer peripheral surface of the second bearing.

7. The rotating device according to claim 4, wherein: The hardness of the first bearing, the hardness of the second bearing, and the hardness of the bushing are the same.

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