JP5068346B2 - Bearing structure - Google Patents

Description

    The present invention relates to a bearing portion structure using a needle roller bearing.

    In general, a bearing portion structure comprising an outer member, an inner member loosely fitted to the outer member, and a needle roller bearing interposed between the outer and inner members is used in various devices such as cranks of internal combustion engines. As an example used in an eccentric oscillating gear device, such as that described in Patent Document 1 below is known.

JP 2000-154849 A Japanese Patent Laid-Open No. 9-203451

  This is an external gear as an outer member in which a large number of internal teeth are formed on the inner periphery and a large number of external teeth meshing with the internal teeth are formed on the outer periphery, and through holes are formed in the inner periphery. A crankshaft as an inner member that is loosely fitted in a through hole of the external gear while maintaining a coaxial relationship and is rotated around the central axis by receiving a rotational driving force, and the crank A support that rotatably supports the shaft, and a needle roller bearing that is interposed between the through-hole of the external gear and the eccentric portion of the crankshaft and allows relative rotation between the external gear and the crankshaft. It is provided.

  The needle roller bearing is composed of a plurality of needle rollers that are spaced apart in the circumferential direction and a cage that rotatably supports the needle rollers. Among them, there is only an annular gap of a slight width between the outer periphery and the eccentric part, and the through hole, and the annular gap between the inner periphery and the eccentric part of the both side walls is Since the needle rollers are closed by inner races of washers or tapered roller bearings that restrict axial movement, the needle rollers are provided on both sides of the external gear (through hole), the eccentric part of the crankshaft, and the cage of the needle roller bearings. It is housed in a semi-enclosed space defined by walls.

    In such a conventional bearing portion structure, as described in Patent Document 2, a lubricant that lubricates the needle rollers is usually stored together with the needle rollers in a semi-enclosed space. However, since such a lubricant is in a semi-sealed state, it is hardly replaced, and as a result, when used for a long period of time, the lubricant deteriorates and the lubricating performance deteriorates, and the needle roller bearing is damaged. There was a problem that it might end up.

  An object of the present invention is to provide a bearing structure in which the lubricant in the semi-enclosed space can be easily replaced with a simple structure.

These objects, and external gear through hole in the inner portion is formed, a crankshaft eccentric portion in the through hole of the external gear is loosely fitted while maintaining a coaxial relationship, the through hole of the external gear and while being interposed between the eccentric portion of the loosely fitted a crankshaft through hole, the circumferential direction into a plurality of which are spaced apart needle roller and rotatably supports the needle rollers And a cage defining a semi-enclosed space in which the needle rollers are housed by both side walls, the external gear, and the crankshaft, and permitting relative rotation between the external gear and the crankshaft. A washer is sandwiched between the needle roller bearing, a pair of washer disposed in close contact with both ends of the needle roller bearing and overlapping the radially inner side of the cage, and the eccentric portion of the crankshaft. a bearing portion structure odor having an inner race of tapered roller bearings , On at least one of the washers, circumferentially radially outward from a plurality of lubricant passages through which can be communicated with the semi-enclosed space the inner race through gap between the inner periphery and the crankshaft side wall of the retainer It is possible to achieve this by a bearing portion structure that is formed at an equal distance from each other and that allows the lubricant to flow into and out of the semi-enclosed space through the lubrication passage that is not closed by the inner race and the gap.

In the above inventions, the one of the washers even without low, to form a plurality of lubrication passages through which can be communicated with the semi-enclosed space through the gap between the side wall inner periphery and the crank shaft of the retainer As a result, the lubricant flows into and out of the semi-enclosed space through these lubrication passages. As a result, the amount of lubricant exchange in the semi-enclosed space increases, and the breakage of the needle roller bearing is effectively suppressed. In addition, the relative rotational speed of the crankshaft and the external gear can be increased.

It is front sectional drawing which shows an example of a bearing part structure. It is II sectional view taken on the line of FIG. It is an expanded front sectional view near the needle roller bearing. It is a right view of a crankshaft. It is a right view of the needle roller bearing which shows the other example of a bearing part structure . FIG. 4 is an enlarged front sectional view in the vicinity of a needle roller bearing similar to FIG. 3 showing Embodiment 1 of the present invention. It is a right side view of the vicinity of the crankshaft and the needle roller bearing.

Hereinafter, an example of the bearing portion structure will be described with reference to the drawings.
In FIGS. 1, 2, and 3, reference numeral 11 denotes an eccentric oscillating gear device used for a robot or the like. The gear device 11 is, for example, a substantially cylindrical shape attached to a robot arm or hand (not shown). A rotating case 12 is provided. A large number of pin grooves 13 having a semicircular cross section are formed in the central portion in the axial direction on the inner periphery of the rotating case 12, and these pin grooves 13 extend in the axial direction and are arranged at equal distances in the circumferential direction. ing.

  14 is an internal tooth composed of a large number of cylindrical pins (the same number as the pin groove 13), and almost half of these internal teeth 14 are inserted into the pin groove 13 so that the inner periphery of the rotating case 12 They are provided equidistantly in the circumferential direction. The rotating case 12 and the internal teeth 14 described above constitute an internal gear 15 provided with internal teeth 14 formed of a plurality of cylindrical pins on the inner periphery.

  In the internal gear 15, a plurality (only two in this case) of external gears 18 as ring-shaped outer members are arranged and stored in the axial direction. A trochoidal tooth profile is provided on the outer periphery of the external gears 18. Specifically, a large number of external teeth 19 each having a peritrochoidal tooth profile are formed. Here, the number of external teeth 19 of the external gear 18 is slightly smaller than the number of teeth of the internal teeth 14, and the external gear 19 and the internal gear 15 are in contact with the external teeth 19 The internal teeth 14 mesh with each other, but the phase of the maximum meshing portion (the deepest meshing portion) of the two external gears 18 is shifted by 180 degrees.

  Each of the external gears 18 is formed with a plurality of, in this case, three, loose fitting holes 22 penetrating in the axial direction, and these loose fitting holes 22 are spaced equidistantly from the central axis of the external gear 18 in the radial direction, They are arranged equidistantly in the circumferential direction. The loose fitting hole 22 has a substantially base shape with a circumferential width increasing toward the outside in the radial direction.

  Reference numeral 25 denotes a support loosely fitted in the rotary case 12 and attached to a fixed robot member (not shown). The support 25 has a pair of substantially ring shapes disposed on both outer sides in the axial direction of the external gear 18. A plurality of end plate portions 26 and 27 to be presented, one end integrally connected to the end plate portion 26 and the other end detachably connected to the end plate portion 27 by a plurality of bolts 28 (the same number as the loose fitting holes 22) It is comprised from the pillar part 29 of this. The column portion 29 that connects the end plate portions 26 and 27 extends in the axial direction and is loosely fitted in the loose fitting hole 22 of the external gear 18 while maintaining a slight gap.

  31 and 32 are a pair of bearings interposed between the support 25, specifically, the outer periphery of the end plate portions 26 and 27 and the inner periphery of both end portions in the axial direction of the rotary case 12, and these bearings 31 and 32 The internal gear 15 is rotatably supported by the support body 25. Reference numeral 33 denotes an axially extending through-hole formed in each external gear 18 at least one, here three, and the plurality of through-holes 33 are equidistant from each other in the circumferential direction. They are arranged alternately with the loose-fitting holes 22 and are arranged equidistant from the central axis in the radial direction.

  Reference numeral 35 denotes at least one crankshaft as an inner member (the same number as the through-holes 33). These crankshafts 35 are arranged at equal angular intervals in the circumferential direction and are fitted on one end in the axial direction. A tapered roller bearing 36 and a tapered roller bearing 37 fitted on the other end in the axial direction thereof are rotatably supported by the support body 25, specifically the end plate portions 26 and 27.

  The crankshaft 35 has two eccentric portions 38 that are eccentric at a part thereof, here the central portion in the axial direction, by an equal distance from the central axis of the crankshaft 35, and these eccentric portions 38 are slightly separated in the axial direction. At the same time, they are 180 degrees out of phase with each other. The eccentric portion 38 of the crankshaft 35 is loosely fitted in the through-holes 33 of the external gear 18 while maintaining a coaxial relationship with each other, and the through-hole 33 of the external gear 18 and the eccentric portion 38 of the crankshaft 35 are fitted. A needle roller bearing 39 is interposed between the external gear 18 and the external gear 18 and the crankshaft 35 to allow relative rotation.

  An external gear 40 is fixed to one end of each crankshaft 35 in the axial direction, and an external gear 42 provided at one end of an output shaft 41 of a drive motor (not shown) meshes with these external gears 40. As a result, when the drive motor operates and the external gear 40 rotates, the crankshaft 35 rotates around its own central axis, and as a result, the eccentric portion 38 of the crankshaft 35 is located in the through hole 33 of the external gear 18. As a result, the external gear 18 rotates eccentrically. At this time, the number of teeth of the external teeth 18 of the external gear 18 is slightly smaller than the number of pins of the internal teeth 14, and here is one, so that the internal gear 15 and the robot arm are decelerated and rotate at a low speed.

  A seal member 45 is interposed between one axial end portion of the rotating case 12 and the end plate portion 26 of the support 25, and a cover (not shown) is attached to one end surface of the end plate portion 26. As a result, one side of the gear unit 11 is closed by the seal member 45 and the cover. On the other hand, a seal member (not shown) is interposed between the case of the drive motor fixed to the other end surface of the end plate portion 27 and the arm of the robot. The side is closed by a drive motor and an arm. As a result, a sealed storage space is formed in the gear device 11, and at least the amount of the through-holes 33 is immersed in the storage space, in this case from full lubricating oil, grease, etc. A lubricant is stored.

  Here, as shown in FIGS. 2 and 3, each of the needle roller bearings 39 described above is a plurality of needle-like cylinders that are arranged equidistantly in the circumferential direction and extend parallel to the central axis of the through-hole 33. The roller 48 and a retainer 49 that rotatably supports the needle rollers 48 are configured. Here, the retainer 49 has ring-shaped side walls 49a and 49b at both ends in the axial direction. The inner diameters of these side walls 49a and 49b are slightly larger than the outer diameter of the eccentric portion 38, while The diameter is slightly smaller than the inner diameter of the through hole 33. As a result, of the side walls 49a and 49b, there is only an annular gap having a slight width between the outer periphery and the eccentric portion 38 and the through hole 33.

  50 is arranged in close contact with both side ends of the needle roller bearing 39, specifically, sandwiched between the inner races 36a, 37a of the tapered roller bearings 36, 37 and the axially outer end surfaces of the two eccentric portions 38. Ring-shaped washers that restrict the axial movement of the cage 49, and these washers 50 overlap each other while being in close contact with the radially inner portions of both side walls 49a, 49b of the cage 49. A radially inner annular gap formed between the inner periphery of the side walls 49a and 49b and the outer periphery of the eccentric portion 38 is closed by the washer 50. For this reason, the needle roller 48 is accommodated by the external gear 18 (through hole 33), the crankshaft 35 (eccentric portion 38), the side walls 49a, 49b of the retainer 49, and the washer 50. A semi-enclosed space 51 is defined.

  Here, as described above, since the lubricant is stored in an amount sufficient to immerse all the through holes 33 in the storage space, the needle rollers 48 are lubricated in the semi-sealed space 51 as well. Although the lubricant is full, since such a lubricant is in a semi-sealed state, the lubricant is hardly replaced. As a result, when used for a long period of time, the lubricant deteriorates and the lubricating performance deteriorates. The roller bearing 39 may be damaged.

  For this reason, in this example, the lubrication passage 53 is formed in the crankshaft 35, the lubricant is caused to flow into the semi-enclosed space 51 through the lubrication passage 53, and the lubricant in the semi-enclosed space 51 is replaced. . Here, the lubrication passage 53 extends through the central axis of the crankshaft 35 and has a shaft hole 54 that opens at both axial end surfaces of the crankshaft 35 and a hole diameter smaller than the outer diameter of the needle roller 48. The inner end in the radial direction communicates with the shaft hole 54, and the outer end in the radial direction is composed of a plurality (the same number as the eccentric portions 38) of the radial holes 55 opened on the outer periphery of each eccentric portion 38.

  As a result, one end of the lubrication passage 53 (radial outer end of the radial hole 55) opens to the outer surface (outer periphery) of the crankshaft 35 (eccentric portion 38) at a position communicating with the semi-sealed space 51, The other end (both ends in the axial direction of the shaft hole 54) is opened to the outer surface (both end surfaces in the axial direction) of the crankshaft 35 radially inward from the one end at a position away from the semi-sealed space 51. Thereby, when the crankshaft 35 rotates, the lubricant located in the vicinity of one end opening of the lubrication passage 53 (radially outer end opening of the radial hole 55), that is, radially outward from the rotation center axis of the crankshaft 35. A large centrifugal force based on the rotation acts on the lubricant at a position far away.

  As a result, the lubricant in the storage space is sucked from the other end opening of the lubrication passage 53 (both ends in the axial direction of the shaft hole 54) and then flows through the lubrication passage 53 to open one end (the radial direction of the radial hole 55). While being swung out from the outer end opening) and supplied to the semi-enclosed space 51, the lubricant is discharged from the semi-enclosed space 51 to the storage space through the annular gap on the outer side in the radial direction. Circulate in the sealed space 51.

  Here, one end of the above-described lubrication passage 53 communicates with the semi-sealed space 51, and may be opened at any position as long as it is located radially outside the other end opening. May be open to the outer periphery of the crankshaft 35 between the eccentric portions 38. One end of the lubrication passage 53 is preferably opened at at least one of the maximum eccentric position and the minimum eccentric position of the eccentric portion 38.

  The reason is that when the crankshaft 35 is rotated, a load does not act on the maximum eccentric position or the minimum eccentric position of the eccentric portion 38, so if one end of the lubrication passage 53 is opened at a position where this load does not act, It is possible to prevent the load from becoming uneven and the needle roller 48 from being damaged by the one end opening edge of the lubrication passage 53, thereby preventing the needle roller 48 and the eccentric portion 38 from being damaged. Since one end of the lubrication passage 53 has a relatively wide range in which the above-described load does not act and the molding operation is facilitated, it is more preferable to open at one end of the eccentric portion 38 as in this example.

Next, the operation of the example will be described.
Now, it is assumed that the drive motor is operating and the crankshaft 35 is rotating. At this time, the eccentric portion 38 of the crankshaft 35 eccentrically rotates in the through-hole 33 of the external gear 18 to rotate the external gear 18 in an eccentric swinging manner, but the number of teeth of the external teeth 19 of the external gear 18 is Since the number of internal teeth (pins) 14 is slightly smaller (only one), the rotating case 12 and the robot arm and the like rotate at a low speed due to the eccentric oscillation rotation of the external gear 18.

  Here, when the crankshaft 35 rotates as described above, a large centrifugal force based on the rotation acts on the lubricant located in the vicinity of one end opening of the lubricating passage 53 (radial outer end opening of the radial hole 55). As a result, the lubricant in the storage space is sucked from the other end opening of the lubrication passage 53 (both ends in the axial direction of the shaft hole 54), and then flows through the lubrication passage 53 to open the one end (the radius of the radial hole 55). And is supplied to the semi-enclosed space 51.

  At this time, since the lubricant is discharged from the semi-enclosed space 51 to the storage space through the annular gap on the radially outer side, the lubricant circulates in the storage space, the lubrication passage 53, and the semi-enclosed space 51. Although it is such a simple structure, the lubricant in the semi-enclosed space 51 can be easily replaced, and the lubrication performance does not deteriorate even when used for a long time, and the needle roller bearing 39 Can be effectively suppressed, and the rotational speed of the crankshaft 35 can be increased.

As another example of the bearing portion structure, one shown in FIG. 5 is also known. In this example, at least one of the side walls of the retainer 49, here forms a lubricating passage 60 which penetrates both side walls 49a, to 49b. Here, a plurality of the lubrication passages 60 are formed on both side walls 49 a and 49 b, here, the same number as the needle rollers 48, and are arranged apart from each other in the circumferential direction so as to be positioned between the needle rollers 48. The lubricating passage 60 may slightly overlap the needle roller 48.

  In this way, if the lubricant in the storage space is caused to flow by the rotation of the crankshaft 35 and the external gear 18, this flow causes the lubricant to pass through the lubricating passage 60 in addition to the radially outer annular gap. The lubricant flows into and out of the semi-enclosed space 51, and the lubricant in the semi-enclosed space 51 is easily replaced. If the lubricating passage 60 is inclined in the same direction with respect to the axial direction, for example, is inclined so as to be radially outward as it goes to the other side in the axial direction, the flow of the lubricant along this inclination is generated. The replacement is effectively performed. Other configurations and operations are the same as in the above example.

6 and 7 are views showing Embodiment 1 of the present invention. In this embodiment, at least one of the washers 50, here both washers 50, is formed between the inner periphery of both side walls 49a, 49b of the retainer 49 and the crankshaft 35 (eccentric portion 38). A plurality of through-lubricating passages 63 that can communicate with the semi-sealed space 51 through a radially inner annular gap are formed. Here, the lubricating passage 63 is arranged radially outward from the inner races 36a, 37a so as not to be closed by the inner races 36a, 37a of the tapered roller bearings 36, 37, and is formed in plural at equal distances in the circumferential direction.

In this way, when a flow is generated in the lubricant in the storage space by the rotation of the crankshaft 35 and the external gear 18, the lubricant is added to the lubrication passage 63 in addition to the radially outer annular gap by this flow. It flows into and out of the semi-enclosed space 51 through the annular gap on the radially inner side, and the lubricant in the semi-enclosed space 51 is easily replaced. Note that if the lubricating passage 63 is inclined in the same direction with respect to the axial direction, for example, is inclined so as to be radially outward toward the other side in the axial direction, the flow of the lubricant along this inclination is generated. The replacement is effectively performed. Other configurations and operations are the same as in the above example .

Furthermore, Oite in Example 1 above has been to rotate the inner member (crankshaft 35) relative to the outer member (the external gear 18), in the invention according to claim 1, the inner member On the other hand, the outer member may be rotated. Further, when no edge is generated and the load distribution can be made uniform, a lubricating passage may be formed in the needle roller 48 or the external gear 18.

  The present invention can be applied to a bearing portion structure using a needle roller bearing.

18… Outer member 33… Through hole
35… Inner member 38… Eccentric part
39 ... Needle roller bearings 48 ... Needle rollers
49 ... Retainer 49a, 49b ... Side wall
50 ... Washer 51 ... Semi-enclosed space
53 ... Lubrication passage

Claims (1)

An external gear that inside the through-hole is formed, a crankshaft eccentric portion in the through hole of the external gear is loosely fitted while maintaining a coaxial relationship, loosely fitted into the through hole and the through hole of the external gear while being interposed between the eccentric portion of the crankshaft which is the circumferential direction into a plurality of needle rollers which are spaced apart and rotatably supports the needle rollers, the outer and both side walls gear, is composed of a cage which defines a semi-enclosed space in which the needle rollers in the crankshaft is housed, a needle roller bearing which permits relative rotation between the external gear and the crankshaft, the An inner race of a tapered roller bearing that is disposed in close contact with both ends of the needle roller bearing and sandwiches the washer between a pair of washer that overlaps the radially inner part of the cage and the eccentric part of the crankshaft. in the bearing unit structure with bets, Sukunakutomoizu Or to one of the washers, equidistant a plurality of lubrication passages through which can be communicated with the semi-enclosed space in the circumferential direction in the radially outward from the inner race through gap between the side wall inner periphery and the crank shaft of the retainer A bearing portion structure characterized in that a lubricant is made to flow into and out of a semi-enclosed space through a lubrication passage which is formed apart and is not closed by the inner race and the gap.

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