speed reducer

Abstract

To provide a reduction gear which can arrange a seal attachment part small in a diameter closer to a rotation-center axial line without impairing a function of a penetration hole.SOLUTION: A reduction gear comprises a case, a carrier, a crankshaft and an oscillation gear. The case holds a plurality of inner tooth pins at an internal peripheral face. The carrier is assembled to the case so as to be relatively rotatable, and has a plurality of crank support holes on the same concentric circle with a rotation-center axial line as a center. The crankshaft is supported to the crank support holes. The oscillation gear has an outer gear, and rotates together with an eccentric part of the crankshaft so as to be oscillatory. A plurality of penetration holes and a seal attachment part are arranged at an end face of the carrier in at least one axial direction. The penetration holes at least partially communicate with the crank support holes, and are arranged inside in a radial direction rather than outer side ends of the crank support holes in a radial direction with respect to the radial direction with the rotation-center axial line of the carrier as a center. The seal attachment part surrounds the outside of the plurality of penetration holes.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a speed reducer.

Background Art

[0002] In rotating equipment used in industrial robots, machine tools, etc., a speed reducer is used to reduce the rotation of a rotational drive source such as a motor (for example, see Patent Document 1).

[0003] The speed reducer described in Patent Document 1 includes a cylindrical case, a carrier that is assembled to the case so as to be rotatable relative to the case, a plurality of crank shafts that are rotatably supported by the carrier, and a swing gear that swings and rotates together with the eccentric portion of the crank shaft within the case. A plurality of pin grooves extending in the axial direction are formed on the inner peripheral surface of the case, and cylindrical internal tooth pins are rotatably held in the respective pin grooves.

[0004] A plurality of crank support holes are formed on the carrier on concentric circles centered on the rotation center axis of the carrier, and journal portions of the crank shafts are rotatably supported in the respective crank support holes. The power of the rotational drive source is transmitted to the plurality of crank shafts through a common input gear. Further, an output rotating body that is a power transmission target is connected to one end face of the carrier in the axial direction.

[0005] External teeth having slightly fewer (for example, one) teeth than the internal tooth pins on the case side are formed on the outer peripheral surface of the swing gear. The swing gear meshes while the outer teeth on the outer periphery are in sliding contact with the internal tooth pins on the case side, and receives a reaction force in the rotational direction from the internal tooth pins while swinging and rotating together with the eccentric portion of the crank shaft, and rotates about the rotation center axis at a predetermined pitch. The rotation component of the swing gear is transmitted to the carrier through the crank shaft, and further transmitted from the carrier to the output rotating body. As a result, the rotation input to the crank shaft is decelerated to a predetermined reduction ratio in the speed reducer to rotate the output rotating body.

[0006] Furthermore, the multiple crank support holes formed in the carrier open to one axial end of the carrier with a nearly constant inner diameter. More precisely, the crank support holes that support the crankshaft communicate with one axial end of the carrier through through holes of the same inner diameter. The through-hole formed on one axial end of the carrier functions as an outlet for removing cutting debris from the carrier when the crank support hole is machined into the carrier after the carrier's general shape has been formed by forging or casting, and also functions as an assembly hole when the bearing or crankshaft is assembled into the crank support hole. The through-hole is closed by a separate cover member after the bearing or crankshaft has been assembled into the crank support hole. This prevents the lubricating fluid inside the reducer from leaking out through the through-hole after the output rotating body is coupled to one axial end face of the carrier.

[0007] In the gearbox described in Reference 1, the leakage of lubricating fluid from one end of the carrier in the axial direction is prevented by attaching a cover member to the through hole. However, the following methods are also employed as means of preventing lubricating fluid leakage. (a) A sealant is applied to one axial end face of the carrier so as to surround the outside of multiple through holes, and the space between the carrier and the end face of the output rotating body is sealed with the applied sealant. (b) An annular seal groove (seal mounting portion) is formed on one axial end face of the carrier so as to surround the outside of a plurality of through holes, and a sealing member such as an O-ring is attached to the seal groove to seal the space between the carrier and the end face of the output rotating body with the sealing member. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2021-139385 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, the gearbox described in Patent Document 1 employs a structure in which the through-hole on the end face of the carrier is sealed by a separate cover member. Therefore, there is a possibility that the cover member may fall out of the through-hole after the end face of the carrier is connected to the output rotating body.

[0010] Furthermore, when applying sealant to the periphery of multiple through holes on the end face of a carrier, uneven application and variations in sealant thickness are likely to occur. If there are uneven application or variations in sealant thickness, sufficient leak prevention of lubricating fluid cannot be obtained. Furthermore, if the sealant is applied unevenly or its thickness varies, there is a risk that the sealant may penetrate the through-hole and mix with the lubricant inside the casing, reducing the lubrication performance of the lubricant.

[0011] Furthermore, when sealing the circumferential portion of multiple through holes on the end face of the carrier with a sealing member such as an O-ring, the circumferential portion of the end face of the carrier will be largely occupied by a sealing groove or sealing member with a larger diameter than the virtual circle connecting the radially outer ends of the multiple crank support holes. This is undesirable when trying to reduce the outer diameter of the gearbox, and improvement in this respect is desired.

[0012] The present invention provides a gearbox that allows the seal mounting portion to be positioned with a small diameter closer to the rotational axis without impairing the function of the through hole. [Means for solving the problem]

[0013] A gearbox according to one aspect of the present invention comprises a case that holds a plurality of internal tooth pins on its inner circumferential surface, a carrier that is rotatably mounted to the case and has a plurality of crank support holes arranged concentrically around a rotational axis, a crankshaft rotatably supported in each of the crank support holes of the carrier, and an oscillating gear having fewer teeth on its outer circumferential surface than the internal tooth pins and external teeth that mesh with the internal tooth pins, and which oscillates and rotates together with the eccentric portion of the crankshaft, wherein at least one axial end face of the carrier has a plurality of through holes that communicate with at least a portion of each of the crank support holes and are arranged radially inward from the radial outer end of the crank support holes with respect to the radial direction of the rotational axis of the carrier, and a seal mounting portion that surrounds the outside of the plurality of through holes. A system is in place.

[0014] In this case, the seal mounting portion can be made smaller in diameter than the radially outer end of the crank support hole without impairing the functions of the through hole, such as the function of discharging cutting chips or facilitating the assembly of parts to the crank support hole.

[0015] It is desirable that the through-hole be positioned inside the axial projection area of ​​the communicating crank support hole.

[0016] In this case, when the crank support holes of the carrier are formed by machining, the cutting debris generated from the crank support holes can be effectively discharged to the outside through the through-holes. Furthermore, this method can suppress the reduction in carrier rigidity caused by the opening of the through-holes becoming unnecessarily large.

[0017] The radial center of the through-hole may be positioned such that its distance from the radial center of the crank support hole is less than or equal to half the radius of the crank support hole.

[0018] In this case, a part of the through-hole overlaps with the radial center of the crank support hole when viewed axially of the carrier. Therefore, it becomes possible to easily assemble parts arranged inside the crank support hole such as the crankshaft and crank bearings to the carrier using the through-hole.

[0019] It is desirable that the radial center of the through-hole be arranged on a straight line passing through the rotational center axis and the radial center of the crank support hole among the end faces of the carrier.

[0020] In this case, the overlap between the through-hole and the radial center region of the crank support hole can be increased when viewed axially of the carrier, and the through-hole can be sufficiently close to the inner peripheral surface of the crank support hole in a state where it is close to the rotational center axis. Therefore, when this configuration is adopted, it becomes possible to more easily assemble parts such as the crankshaft and bearings using the through-hole, and it also becomes possible to improve the chip discharge property during cutting of the crank support hole.

[0021] The radius of the through-hole may be set to a radius of 0.39 times or more the radius of the crank support hole.

[0022] In this case, even when chips continuously come out during cutting of the crank support hole, it becomes possible to efficiently discharge the chips to the outside through the through-hole. Therefore, when this configuration is adopted, the frequency of the operation of interrupting the cutting operation to discharge the chips during cutting of the crank support hole can be reduced, and the cutting operation efficiency of the crank support hole can be increased.

[0023] Regarding the radial direction centered on the rotational center axis, the radially inner end of the through-hole may be arranged within a range of a distance less than 0.3 times the radius of the crank support hole from the radially inner end of the crank support hole.

[0024] In this case, since the radially inner end of the through-hole is sufficiently close to the radially inner end of the crank support hole, the chip discharge property during cutting of the crank support hole can be improved.

[0025] In the radial direction centered on the rotation center axis, the radially outer end of the through hole may be arranged to be separated radially outward by a distance of 0.45 times or less the radius of the crank support hole from the radial center of the crank support hole.

[0026] In this case, the through hole is separated radially inward by more than 0.55 times the radius of the crank support hole from at least the radially outer end of the crank support hole. For this reason, the seal mounting portion can be sufficiently arranged with a small diameter closer to the rotation center axis.

[0027] In the radial direction centered on the rotation center axis, the radially outer end of the through hole may be arranged to be separated radially outward by a distance of 0.08 times or more the radius of the crank support hole from the radial center of the crank support hole.

[0028] In this case, the through hole wraps around the radial center of the crank support hole by at least a distance of 0.08 times or more the radius of the crank support hole in the radial direction. For this reason, when assembling the crankshaft, it becomes possible to pass the assembling tool across the through hole and the crank support hole. Therefore, when this configuration is adopted, the workability of assembling the crankshaft and the crank bearing is improved.

[0029] The radius of the through hole is 0.39 times or more and less than 0.725 times the radius of the crank support hole. When the radius of the through hole is Rb, the distance from the rotation center axis to the radial center of the through hole is RB, the radius of the crank support hole is Ra, and the distance from the rotation center axis to the radial center of the crank support hole is RA, the distance RB from the rotation center axis to the radial center of the through hole satisfies the following formulas (a), (b), (c), (d). The speed reducer according to claim 1 or 2. RB - Rb > RA - Ra …(a) RB - Rb ≦ RA - 0.7Ra …(b) RB + Rb ≦ RA + 0.45Ra …(c) RB + Rb ≧ RA + 0.08Ra …(d)

[0030] In this case, the seal mounting portion can be positioned closer to the rotational axis and with a small diameter without impairing the functions of the through-hole, such as the function of discharging cutting chips during machining of the crank support hole and the function of facilitating assembly during crankshaft assembly. Therefore, by adopting this configuration, it is possible to achieve both miniaturization of the reducer and improvement of the sealing performance of the axial end face of the carrier.

[0031] The carrier may be made of carbon steel for machine structures.

[0032] When the carrier is made of carbon steel for machine structures, if the crank support holes of the carrier are formed by machining, cutting chips are continuously generated. In this case, if the through-hole is positioned radially inward from the radially outer end of the crank support hole with respect to the radial direction of the rotational axis, cutting chips can be smoothly discharged to the outside through the through-hole during machining of the crank support hole while suppressing an increase in the diameter of the seal mounting area. [Effects of the Invention]

[0033] In the aforementioned reduction gear, the through-hole opening in the axial end face of the carrier is positioned radially inward from the radially outer end of the crank support hole with respect to the radial direction around the rotation center axis. Therefore, the seal mounting portion can be positioned with a small diameter closer to the rotation center axis without impairing the function of the through-hole. [Brief explanation of the drawing]

[0034] [Figure 1] This is a cross-sectional view corresponding to section II in Figure 2 of the speed reducer according to an embodiment of the present invention. [Figure 2] This is a front view of a part of a gearbox according to an embodiment of the present invention. [Figure 3] This is a front view of a reduction gear in an embodiment, with a portion of Figure 2 enlarged. [Figure 4] This is a cross-sectional view of a modified gearbox similar to that shown in Figure 1. [Modes for carrying out the invention]

[0035] Next, embodiments of the present invention will be described with reference to the drawings.

[0036] Figure 1 is a longitudinal cross-sectional view of the gearbox 10 of the embodiment, and Figure 2 is a front view of a part of the gearbox 10 (first carrier block 13A). Note that Figure 1 corresponds to the cross-section along line II in Figure 2. The reduction gear 10 comprises a substantially cylindrical case 11, a first carrier block 13A and a second carrier block 13B assembled to the inner circumference of the case 11 so as to be rotatable relative to each other, a plurality (for example, three) of crankshafts 14 rotatably supported by the first carrier block 13A and the second carrier block 13B, and a first oscillating gear 15A and a second oscillating gear 15B that oscillate and rotate together with two eccentric portions 14b of each crankshaft 14. In this embodiment, the first carrier block 13A and the second carrier block 13B constitute the carrier. The first oscillating gear 15A and the second oscillating gear 15B constitute the oscillating gear in this embodiment. In this embodiment, the oscillating gear is composed of the first oscillating gear 15A and the second oscillating gear 15B, but the number of oscillating gears installed may be one or three or more.

[0037] The first carrier block 13A has a perforated disc-shaped base portion 13Aa and a plurality (for example, three) of support portions 13Ab extending from the end face of the base portion 13Aa toward the second carrier block 13B. The second carrier block 13B is formed in the shape of a perforated disc. The end faces of the support portions 13Ab of the first carrier block 13A are abutted against the end face of the second carrier block 13B, and each support portion 13Ab is fastened and fixed to the second carrier block 13B by bolts 16.

[0038] An axial gap is provided between the substrate portion 13Aa of the first carrier block 13A and the second carrier block 13B. The first oscillating gear 15A and the second oscillating gear 15B are positioned in this gap. Furthermore, the first oscillating gear 15A and the second oscillating gear 15B have relief holes 19 through which each support column 13Ab of the first carrier block 13A passes. The relief holes 19 are formed to be sufficiently larger than the outer surface shape of the support column 13Ab so that the support column 13Ab does not obstruct the oscillating rotation (rotation) of the first oscillating gear 15A and the second oscillating gear 15B.

[0039] Case 11 is positioned across the outer circumferential surface of the base portion 13Aa of the first carrier block 13A and the outer circumferential surface of the second carrier block 13B. The base portion 13Aa of the first carrier block 13A and the second carrier block 13B are rotatably supported at both axial ends of case 11 via main bearings 12. In addition, a plurality of pin grooves 18 are formed on the inner circumferential surface of the central axial region of case 11 (the region facing the outer circumferential surfaces of the first oscillating gear 15A and the second oscillating gear 15B), extending parallel to the rotational axis c1 of the first and second carrier blocks 13A and 13B.

[0040] Each pin groove 18 on the inner circumference of case 11 rotatably houses a substantially cylindrical internal tooth pin 20. The multiple internal tooth pins 20 housed in the pin grooves 18 of case 11 face the outer surfaces of the first oscillating gear 15A and the second oscillating gear 15B.

[0041] The first oscillating gear 15A and the second oscillating gear 15B are formed with an outer diameter slightly smaller than the inner diameter of the case 11. External teeth 15Aa and 15Ba are formed on the outer circumferential surfaces of the first oscillating gear 15A and the second oscillating gear 15B, respectively, which slide in a meshing state with a plurality of internal tooth pins 20 located in the inner circumference (pin groove 18) of the case 11. The number of teeth on the external teeth 15Aa and 15Ba formed on the outer circumferential surfaces of the first oscillating gear 15A and the second oscillating gear 15B is set to be slightly less than the number of internal tooth pins 20 (number of pin grooves 18) (for example, one less).

[0042] Multiple crankshafts 14 are arranged on the same circumference centered on the rotational axis c1 of the first carrier block 13A and the second carrier block 13B. Each crankshaft 14 is rotatably supported by the first carrier block 13A and the second carrier block 13B via crank bearings 21. Each crankshaft 14 has a pair of journal portions 14a spaced apart in the axial direction, with two eccentric portions 14b positioned between the pair of journal portions 14a.

[0043] The base portion 13Aa of the first carrier block 13A has a plurality of crank support holes 22A formed therein for supporting one axial end of the crankshaft 14 via a crank bearing 21. The crank support holes 22A are formed with an inner diameter slightly larger than that of the crank bearing 21. The plurality of crank support holes 22A are arranged at equal intervals on concentric circles centered on the rotational axis c1 of the first carrier block 13A. In addition, the base portion 13Aa of the first carrier block 13A has a plurality of through holes 23 that communicate with each crank support hole 22A. The through holes 23 are formed with a smaller diameter than the crank support holes 22A. The through holes 23 will be described in detail later.

[0044] The second carrier block 13B has a plurality of crank support holes 22B formed therein for supporting the other axial end of the crankshaft 14 via a crank bearing 21. The other axial end of each crankshaft 14 protrudes through the crank support holes 22B to the other axial end of the second carrier block 13B. A gear mounting portion 14c is formed at the other axial end of each crankshaft 14. A crank gear 24 is attached to the gear mounting portion 14c of each crankshaft 14. Each crank gear 24 meshes with a common input gear (not shown). The input gear is connected to the output shaft of a rotational drive source such as an electric motor.

[0045] The two eccentric portions 14b of the crankshaft 14 have their respective central axes c3 eccentric with respect to the central axis c2 of the journal portion 14a. Furthermore, the two eccentric portions 14b are eccentric such that their phases are shifted by 180° around the central axis c2 of the journal portion 14a. The radial center h of the crank support hole 22A coincides with the central axis c2 of the crankshaft 14 (journal portion 14a).

[0046] Furthermore, each eccentric portion 14b of the crankshaft 14 passes through the first oscillating gear 15A and the second oscillating gear 15B, respectively. Each eccentric portion 14b is rotatably mounted to the first oscillating gear 15A and the second oscillating gear 15B via eccentric portion bearings 26 (cylindrical roller bearings) in support holes 25 formed in the first oscillating gear 15A and the second oscillating gear 15B, respectively. Furthermore, the first carrier block 13A and the second carrier block 13B are connected to the first oscillating gear 15A and the second oscillating gear 15B in a manner that prevents relative rotation, via a plurality of crankshafts 14 arranged around the rotational axis c1. Therefore, when the first oscillating gear 15A and the second oscillating gear 15B rotate in one direction, the first carrier block 13A and the second carrier block 13B rotate in sync with their rotation.

[0047] In this embodiment, when the multiple crankshafts 14 rotate in one direction under the power of a rotational drive source, each eccentric portion 14b of the crankshafts 14 oscillates (rotates) in the same direction at a predetermined radius, and consequently, the first oscillating gear 15A and the second oscillating gear 15B oscillate (rotate) in the same direction at the same radius. At this time, the external teeth 15Aa and 15Ba of the first oscillating gear 15A and the second oscillating gear 15B slide in contact with a plurality of internal tooth pins 20 held on the inner circumference of the case 11 so as to mesh with them.

[0048] In the reduction gear 10, the number of teeth on the external teeth 15Aa and 15Ba of the first oscillating gear 15A and the second oscillating gear 15B is set to be slightly less than the number of internal tooth pins 20 on the case 11 side. Therefore, while the first oscillating gear 15A and the second oscillating gear 15B rotate once, they receive a reaction force in the rotational direction from the internal tooth pins 20 on the case 11 side. As a result, the first oscillating gear 15A and the second oscillating gear 15B rotate on their own by a predetermined pitch in the opposite direction to the oscillating rotation (rotational direction). The first and second carrier blocks 13A and 13B, which are assembled to the first and second oscillating gears 15A and 15B via the crankshaft 14, rotate together with the first and second oscillating gears 15A and 15B in the same direction and at the same pitch. In this embodiment, the case 11 is fixed together with the rotation drive source to a support structure (not shown), and the first carrier block 13A is connected to the object to be rotated 27. Therefore, the rotational power of the rotation drive source is reduced to a predetermined reduction ratio by the reduction gear 10, and then rotates the object to be rotated 27 via the first carrier block 13A. However, it is also possible to fix the first carrier block 13A to a support structure and connect the case 11 to the object to be rotated.

[0049] Multiple fastening holes 28 for bolting the object to be rotated 27 are formed on the axially outer end face of the first carrier block 13A. Multiple fastening holes 28 are formed along the circumferential direction on the outer peripheral edge of the base portion 13Aa of the first carrier block 13A. The fastening holes 28 are arranged in two radial stages on the outer peripheral edge of the base portion 13Aa.

[0050] Furthermore, an annular seal groove 29, which is a seal mounting portion, is formed on the axially outer end face of the substrate portion 13Aa, radially inward from the plurality of fastening holes 28 and radially outward from the plurality of through holes 23. The seal groove 29 is formed in a circular shape centered on the rotational axis c1 of the first carrier block 13A. The seal groove 29 is formed to surround the outside of the plurality of through holes 23. A sealing member, such as an O-ring (not shown), is housed inside the seal groove 29. When the rotating object 27 is bolted to the axially outer end face of the first carrier block 13A with the sealing member housed in the seal groove 29, the first carrier block 13A and the end face of the rotating object 27 come into close contact with each other. This prevents the lubricating fluid inside the reduction gear 10 from leaking out through the gap at the abutting joint between the first carrier block 13A and the rotating object 27.

[0051] Figure 3 is a front view of the first carrier block 13A, which is an enlarged portion of Figure 2. The through hole 23, which opens axially outward from the first carrier block 13A, is positioned radially inward from the radially outer end j of the communicating crank support hole 22A, with respect to the radial direction around the rotational axis c1 of the first carrier block 13A. Furthermore, each through-hole 23 is formed in a circular shape with a smaller diameter than the crank support hole 22A, and is positioned inside the axial projection area of ​​the communicating crank support hole 22A (see dotted line 22A in Figures 2 and 3). In addition, the through-hole 23 is positioned in the first carrier block 13A such that its radial center g lies on a straight line L1 passing through the rotational axis c1 and the radial center h of the crank support hole 22A.

[0052] Furthermore, the dimensions of each part of each through-hole 23 are set to satisfy the following equations (1) to (6). <Distance between the rotational axis c1 and the radial center g of the through hole 23> RA>RB>RA-Ra / 2 …(1) RA: Distance from the rotational axis c1 to the radial center h of the crank support hole 22A. RB: Distance from the rotational axis c1 to the radial center g of the through hole 23. Ra: Radius of crank support hole 22A

[0053] <Radius of through-hole 23> Rb≧0.30Ra …(2) Ideally, Rb ≥ 0.45Ra Rb: Radius of through hole 23

[0054] <Distance from the rotational axis c1 to the radial inner end (innermost end) of the through hole 23> RBin>RAin Therefore, RB-Rb > RA-Ra …(3) RBin: Distance from the rotational axis c1 to the radial inner end of the through hole 23 RAin: Distance from the rotational axis c1 to the radially inner end of the crank support hole 22A

[0055] <Distance from the rotational axis c1 to the radial inner end (innermost end) of the through hole 23> RBin≦RA-0.7Ra Therefore, RB-Rb≦RA-0.7Ra …(4)

[0056] <Distance from the rotational axis c1 to the radial outer end (outermost end) of the through hole 23> RBex≦RA+0.45Ra Therefore, RB + Rb ≤ RA + 0.45Ra …(5) RBex: Distance from the rotational axis c1 to the radial outer end (outermost end) of the through hole 23.

[0057] <Distance from the rotational axis c1 to the radial outer end (outermost end) of the through hole 23> RBex≧RA+0.08Ra Therefore, RB + Rb ≥ RA + 0.08Ra …(6)

[0058] Furthermore, the following conditions can be derived from the above equations. From equations (3) and (6), RB>RA-0.46Ra …(7) From equations (3) and (5), Rb < 0.725Ra …(8) From equations (4) and (6), Rb≧0.39Ra …(9) From equations (4) and (5), RB ≤ RA - 0.125Ra …(10)

[0059] Based on these, the respective ranges for Rb and RB are as follows: 0.39Ra ≤ Rb < 0.725Ra …(11) RA-0.46Ra <RB≦RA-0.125Ra…(12)

[0060] Furthermore, in this embodiment, the first carrier block 13A and the second carrier block 13B are made of carbon steel for machine structures, and their general shapes are formed by forging. Then, the first carrier block 13A is formed by forging to create the general shape of each through hole 23 and crank support hole 22A, after which the crank support hole 22A is precisely machined using a cutting tool. At this time, the cutting chips generated during the machining of each crank support hole 22A are discharged to the outside through the through hole 23 which communicates with the crank support hole 22A. Similarly, the second carrier block 13B is formed by forging to create the general shape of the crank support hole 22B, after which the crank support hole 22B is precisely machined using a cutting tool. Furthermore, after machining crank support holes 22A and 22B in the first carrier block 13A and the second carrier block 13B with a cutting tool, the crank bearing 21 and the crankshaft 14 are assembled into these crank support holes 22A and 22B. At this time, the crank bearing 21 and the crankshaft 14 are assembled into the crank support hole 22A on the first carrier block 13A side using a through hole 23.

[0061] As described above, in the reduction gear 10 of this embodiment, the through hole 23 opening to the axial end face of the first carrier block 13A (carrier) is positioned radially inward from the radial outer end j of the crank support hole 22A with respect to the radial direction around the rotational axis c1. Therefore, in the reduction gear 10 of this embodiment, the seal groove 29 (seal mounting portion) can be positioned with a small diameter closer to the rotational axis c1 without impairing the function of the through hole 23. Therefore, by adopting the gearbox 10 of this embodiment, it is possible to reduce the outer diameter of the first carrier block 13A and improve the function of preventing lubrication leakage without impairing the basic function of the through hole 23.

[0062] Furthermore, in this embodiment, the reduction gear 10 has a through hole 23 in the first carrier block 13A (carrier) positioned inside the axial projection area of ​​the communicating crank support hole 22A. Therefore, when the crank support hole 22A of the first carrier block 13A is formed by cutting, cutting chips coming out of the crank support hole 22A can be effectively discharged to the outside through the through hole 23. In addition, in this case, a decrease in the rigidity of the first carrier block 13A due to the opening of the through hole 23 becoming unnecessarily large can be suppressed.

[0063] Furthermore, in the reduction gear 10 of this embodiment, the radial center g of the through hole 23 is positioned at a distance of less than or equal to half the radius of the crank support hole 22A from the radial center h of the crank support hole 22A (see equation (1)). As a result, a portion of the through hole 23 coincides with the radial center h of the crank support hole 22A when viewed in the axial direction of the first carrier block 13A. Therefore, when this configuration is adopted, components that are placed inside the crank support hole 22A, such as the crankshaft 14 and crank bearings 21, can be easily assembled to the first carrier block 13A using the through hole 23.

[0064] Furthermore, in the reduction gear 10 of this embodiment, the radial center g of the through hole 23 is positioned on a straight line L1 passing through the rotational axis c1 and the radial center h of the crank support hole 22A on the end face of the first carrier block 13A. Therefore, in an axial view of the first carrier block 13A, the overlap between the region near the radial center h of the through hole 23 and the region near the radial center h of the crank support hole 22A is increased, and the through hole 23 can be brought close to the rotational axis c1 while also being sufficiently close to the inner circumferential surface of the crank support hole 22A. Therefore, by adopting this configuration, components such as the crankshaft 14 and crank bearings 21 can be assembled more easily using the through holes 23, and the removal of cutting chips during machining of the crank support holes 22A can be improved.

[0065] Furthermore, in this embodiment, the radius of the through-hole 23 of the gearbox 10 is set to be at least 0.39 times the radius of the crank support hole 22A (see equation (11)). Therefore, even if cutting chips are continuously generated during machining of the crank support hole 22A, the cutting chips can be efficiently discharged to the outside through the through-hole 23. Therefore, by adopting this configuration, the frequency of interrupting the cutting operation to discharge cutting chips during the cutting of the crank support hole 22A can be reduced, thereby improving the efficiency of the cutting operation of the crank support hole 22A.

[0066] Furthermore, in the reduction gear 10 of this embodiment, with respect to the radial direction around the rotational axis c1, the radial inner end f of the through hole 23 is positioned within a distance of less than 0.3 times the radius of the crank support hole 22A from the radial inner end e of the crank support hole 22A (see equation (4)). Therefore, when this configuration is adopted, the radial inner end f of the through hole 23 will be sufficiently close to the radial inner end e of the crank support hole 22A, resulting in good chip evacuation during cutting of the crank support hole 22A.

[0067] Furthermore, in this embodiment, the reduction gear 10 is positioned such that, with respect to the radial direction around the rotational axis c1, the radial outer end i of the through hole 23 is located radially outward from the radial center h of the crank support hole 22A by a distance of 0.45 times the radius of the crank support hole 22A or less (see equation (5)). As a result, the through hole 23 is located radially inward from at least 0.55 times the radius of the crank support hole 22A from the radial outer end j of the crank support hole 22A. Therefore, by adopting this configuration, the seal groove 29 (seal mounting portion) can be positioned with a sufficiently small diameter closer to the rotational axis c1, thereby further reducing the diameter of the first carrier block 13A.

[0068] Furthermore, in this embodiment, the reduction gear 10 is positioned such that, with respect to the radial direction around the rotational axis c1, the radial outer end i of the through hole 23 is located radially outward from the radial center h of the crank support hole 22A by a distance of at least 0.08 times the radius of the crank support hole 22A (see equation (6)). As a result, the through hole 23 overlaps radially with the crank support hole 22A in the vicinity of the radial center h by a distance of at least 0.08 times the radius of the crank support hole 22A. Therefore, when this configuration is adopted, it becomes possible to pass the assembly tool across the through hole 23 and the crank support hole 22A when assembling the crankshaft 14, thereby increasing the efficiency of the crankshaft 14 assembly work.

[0069] Furthermore, in this embodiment, the radius of the through hole 23 is set to be 0.39 times or more and less than 0.725 times the radius of the crank support hole 22A, and the distance RB from the rotational axis c1 to the radial center g of the through hole 23 is set to satisfy the above equations (3), (4), (5), and (6). Therefore, the seal groove 29 (seal mounting portion) can be positioned with a small diameter closer to the rotational axis c1 without impairing the basic functions of the through hole 23, such as the function of discharging cutting chips when machining the crank support hole 22A and the function of facilitating assembly when assembling the crankshaft 14. Therefore, by adopting this configuration, it is possible to achieve both increased rigidity of the reduction gear 10 and improved sealing of the axial end face of the first carrier block 13A.

[0070] Furthermore, in this embodiment, the reduction gear 10 has a first carrier block 13A and a second carrier block 13B made of carbon steel for machine structures. This increases the strength and toughness of the first carrier block 13A and the second carrier block 13B. On the other hand, if the first carrier block 13A is made of carbon steel for machine structures, cutting chips are continuously generated when the crank support hole 22A is cut. However, if the reduction gear 10 of this embodiment is used, the cutting chips can be smoothly discharged to the outside through the through hole 23 when the crank support hole 22A is cut.

[0071] <Variation> Figure 4 is a cross-sectional view of a modified reduction gear 110, similar to that shown in Figure 1. The reduction gear 110 of this modified example has a basic configuration that is almost the same as that of the above embodiment, but differs in that a stepped circular recess 40 is formed on the axially outer end face of the first carrier block 13A. In this modified example, the connection of the rotating object 27 to the first carrier block 13A can be stabilized by fitting a circular protrusion (not shown) on the end face on the rotating object 27 side into the circular recess 40 of the first carrier block 13A. The through-hole 23 of the first carrier block 13A opens to the inside (bottom surface) of the circular recess 40. The arrangement of the through-hole 23 is the same as in the embodiment described above. The seal groove 29 is located radially outward of the circular recess 40.

[0072] It should be noted that the present invention is not limited to the embodiments described above, and various design modifications are possible without departing from the spirit of the invention. For example, in the above embodiment, the radial center g of the through hole 23 is located on a straight line L1 that passes through the rotational axis c1 and the radial center h of the crank support hole 22A on the axial end face of the first carrier block 13A, but the arrangement of the through hole 23 is not limited to this. The through hole 23 may be located radially inward from the radial outer end j of the crank support hole 22A, so that its radial center g is off the straight line L1.

[0073] Furthermore, in the above embodiment, the through-hole 23 is positioned inside the axial projection area of ​​the crank support hole 22A, but the arrangement of the through-hole 23 is not limited to this. The through-hole 23 may be positioned so that a portion of it is offset outside the axial projection area of ​​the crank support hole 22A, as long as it is radially inward from the radial outer end j of the crank support hole 22A.

[0074] Furthermore, in the above embodiment, a seal groove 29 is provided as a seal mounting portion located on the end face of the first carrier block 13A, but the seal mounting portion is not limited to this. The seal mounting portion may be, for example, a seal contact surface that a seal member held on the rotating object 27 side contacts.

[0075] Furthermore, in the above embodiment, a through hole 23 and a seal groove 29 (seal mounting portion) are provided on the axially outer end face of the first carrier block 13A. However, the through hole 23 and the seal groove 29 (seal mounting portion) may be provided on the axially outer end face of the second carrier block 13B. Furthermore, if the part that inputs power to the crankshaft 14 is located at an end other than the axial end of the crankshaft 14, the through hole 23 and the seal groove 29 (seal mounting portion) can also be located on the end faces of both the first carrier block 13A and the second carrier block 13B.

[0076] Furthermore, in the embodiments disclosed herein, those composed of multiple objects may be integrated, and conversely, those composed of a single object may be divided into multiple objects. Whether or not they are integrated, the invention is only necessary to achieve its objective. [Explanation of Symbols]

[0077] 10…Reducer, 11…Case, 13A…First carrier block (carrier), 13B…Second carrier block (carrier), 14…Crankshaft, 14b…Eccentric part, 15A…First oscillating gear (oscillating gear), 15B…Second oscillating gear (oscillating gear), 15Aa,15Ba…External teeth, 20…Internal tooth pin, 22A…Crank support hole, 23…Through hole, 29…Seal groove (seal mounting part), c1…Rotational axis, L1…Straight line

Claims

1. A case that holds multiple internal tooth pins on its inner surface, A carrier is assembled to the aforementioned case so as to be rotatable relative to it, and has a plurality of crank support holes arranged concentrically around the rotational axis, A crankshaft rotatably supported in each of the crank support holes of the carrier, The system includes an oscillating gear having external teeth on its outer surface that have fewer teeth than the internal tooth pin and mesh with the internal tooth pin, and which oscillates and rotates together with the eccentric portion of the crankshaft, At least one axial end face of the carrier is Multiple through holes communicating with each of the crank support holes, A seal mounting portion surrounding the outside of the multiple through holes, A system was established, The entire through-hole, as viewed from the direction of the rotational axis, is contained within the axial projection region of the corresponding crank support hole, With respect to the radial direction of the carrier's rotational axis, the radial center of the through hole is located radially inward from the radial center of the crank support hole. reducer.

2. The radial center of the through hole is positioned such that its distance from the radial center of the crank support hole is less than or equal to half the radius of the crank support hole. The gearbox according to claim 1.

3. The radial center of the through hole is located on a straight line passing through the rotational axis and the radial center of the crank support hole on the end face of the carrier. The gearbox according to claim 2.

4. The gearbox according to claim 3, wherein the radius of the through hole is set to a radius of 0.39 times or more the radius of the crank support hole.

5. With respect to the radial direction centered on the rotation axis, the radial inner end of the through hole is positioned within a distance of less than 0.3 times the radius of the crank support hole from the radial inner end of the crank support hole. The gearbox according to claim 3 or 4.

6. With respect to the radial direction with respect to the rotational axis, the radial outer end of the through hole is positioned radially outward from the radial center of the crank support hole by a distance of 0.45 times or less the radius of the crank support hole. The gearbox according to claim 3.

7. The gearbox according to claim 6, wherein, with respect to the radial direction with respect to the rotational axis, the radial outer end of the through hole is positioned radially outward from the radial center of the crank support hole by a distance of 0.08 times or more the radius of the crank support hole.

8. The radius of the through-hole is 0.39 times or more and less than 0.725 times the radius of the crank support hole. The gearbox according to claim 1 or 2, where Rb is the radius of the through hole, RB is the distance from the rotational axis to the radial center of the through hole, Ra is the radius of the crank support hole, and RA is the distance from the rotational axis to the radial center of the crank support hole, such that the distance RB from the rotational axis to the radial center of the through hole satisfies the following equations (a), (b), (c), (d). RB-Rb>RA-Ra...(a) RB-Rb≦RA-0.7Ra...(b) RB+Rb≦RA+0.45Ra…(c) RB+Rb≧RA+0.08Ra…(d)

9. The gearbox according to claim 1 or 2, wherein the carrier is made of carbon steel material for machine structures.

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