JP4498816B2 - Eccentric oscillation type planetary gear unit - Google Patents

Description

    The present invention relates to an eccentric oscillating planetary gear device in which an external gear meshing with an internal gear is eccentrically oscillated by a crankshaft.

As a conventional eccentric oscillating planetary gear device, for example, one described in Patent Document 1 below is known.
JP-A-7-299791

  This is a trochoidal tooth profile that has an internal gear provided with internal teeth composed of a large number of cylindrical pins on the inner periphery, a plurality of crankshaft holes and through-holes, and meshes with all teeth on the outer periphery. An external gear having a large number of external teeth, a crankshaft that is inserted into each crankshaft hole and rotates to eccentrically swing the external gear, and rotatably supports the crankshaft. And a support having a plurality of pillars inserted into the holes.

  In this case, as shown in FIG. 6, the action line S of the reaction force K of the driving component force applied from each external tooth 01 to the corresponding internal tooth (pin) 02 is one set point C. However, such a set point C is located between the outer end passing circle G passing through the radially outer ends of all the through holes 03 and the inner end passing circle N passing through the radially inner ends. It was.

    However, in such a conventional eccentric oscillating planetary gear device, the set point C is located between the outer end passing circle G and the inner end passing circle N as described above. When the set point C is positioned near the center of the through hole 03 due to the eccentric oscillating rotation of the gear 04, the action line S of each reaction force K extends substantially in the normal direction with respect to the through hole 03. . Here, in the external gear 04, the bridge portion 05 located on the outer side in the radial direction of the through hole 03 is thinner than other portions, so the rigidity is low. On the other hand, since a part of the reaction force K acts in the direction almost normal to the through-hole 03 as described above, that is, in the direction substantially perpendicular to the extending direction of the bridge portion 05, the bridge portion 05 and the vicinity of the bridge portion 05 The outer teeth 01 are elastically deformed, and the outer teeth 01 and the inner teeth (pins) 02 come into contact with each other, and the tooth surface life of the outer teeth 01 is shortened.

  An object of the present invention is to provide an eccentric oscillating planetary gear device that can extend the life of the tooth surface of the external teeth by suppressing the elastic deformation of the bridge portion and external teeth of the external gear.

    The purpose of this is to form an internal gear provided with internal teeth composed of a large number of cylindrical pins on the inner periphery, at least one crankshaft hole and a plurality of through holes, and from the trochoidal tooth profile on the outer periphery. An external gear having a large number of external teeth meshing with the internal teeth, a crankshaft that is inserted into each crankshaft hole and rotates eccentrically by rotating, and the crankshaft is rotatably supported. In addition, in the eccentric oscillating planetary gear device provided with a support body having a plurality of pillars inserted into each through hole, a reaction force of a driving component force applied from each external tooth to the corresponding internal tooth The set point C where the action lines S of K overlap is between the pin circle P passing through the centers of all the pins constituting the inner teeth and the outer end passing circle G passing through the radially outer ends of all the through holes. Can be achieved by positioning the

  In the present invention, the outer point that passes through the radially outer ends of all the through holes passes through the set point C where the action lines S of the reaction force K of the driving component force applied from the respective outer teeth to the corresponding inner teeth overlap. Since it is positioned radially outward from the end passing circle G, when the set point C is positioned on a radial line passing through the center of the through hole, any line of action S of the reaction force K is also the through hole. On the other hand, it inclines in the tangential direction side from the past, and comes closer to the extending direction of the bridge portion. As a result, the thin and low-rigidity bridge portion and the elastic deformation of the external teeth in the vicinity of the bridge portion are suppressed, and the tooth surface life of the external teeth is extended.

  In addition, when the set point C is located radially outside the outer end passing circle G as described above, the tangential direction component of each reaction force K is not a hollow portion of the through-hole, but has high tangential rigidity. Since the bridge portion is received, deformation of the through hole can be suppressed. However, when the set point C is located radially outward from the pin circle P passing through the centers of all the pins constituting the inner teeth, a pointed portion is generated on the tooth surface of the outer teeth. It must be located between the end passing circle G and the pin circle P.

Here, when the set point C is located between the pin circle P and the root circle M, a part of the reaction force K extends almost tangentially to the external gear, and as a result, The external teeth may be bent and deformed by the reaction force K, but if the set point C is positioned between the root circle M and the outer end passing circle G as described in claim 2, Such a situation can be prevented.
Moreover, if comprised as described in Claim 3, compared with the case where the number-of-teeth difference shall be 2 or more, it can be set as a high reduction ratio, and processing cost can be reduced.

Embodiment 1 of the present invention will be described below with reference to the drawings.
In FIGS. 1, 2, and 3, reference numeral 11 denotes an eccentric oscillating planetary gear device used for a robot or the like. 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 number of cylindrical pins (the same number as the pin groove 13), and almost half of these internal teeth (pins) 14 are inserted into the pin groove 13 so that the rotating case 12 The inner circumference is provided at an equal distance in the circumferential direction. The rotating case 12 and the internal teeth (pins) 14 described above constitute an internal gear 15 provided with internal teeth 14 formed of a plurality of cylindrical pins on the inner periphery. Here, about 25 to 100 inner teeth (pins) 14 are arranged, but preferably in the range of 30 to 80. The reason is that the number of the internal teeth (pins) 14 is within the above-mentioned range, and the required speed ratio can be easily obtained by combining with the external gears 40 and 42 described later, and the natural frequency. This is because a planetary gear device having a high reduction ratio can be configured.

  A plurality of (in this case, two) external gears 18 in the form of a ring are accommodated in the axial direction in the internal gear 15, and a trochoidal tooth profile, more specifically a peritrochoid, is arranged on the outer periphery of the external gear 18. A large number of external teeth 19 each having a tooth shape are formed. The number of external teeth 19 of the external gear 18 is one less than the number of internal teeth (pins) 14 (the difference in the number of teeth is 1). In this way, the difference in the number of teeth between the internal teeth (pins) 14 and the external teeth 19 is set to 1, compared with the case where the difference in the number of teeth is a value R of 2 or more, a high reduction ratio is easily achieved. This is because the processing cost can be reduced.

  Here, the external gear whose tooth number difference is a value R of 2 or more means that the outer contour of the trochoid external gear is shifted in the circumferential direction by an angle obtained by dividing the pitch between the external teeth 19 by the value of R, This is an external gear obtained by taking out a portion where R outlines deviated in the circumferential direction overlap each other as a tooth profile (see Japanese Patent Laid-Open No. 3-181641). The external teeth 19 and the internal teeth (pins) 14 are meshed with each other while the external gear 18 and the internal gear 15 are inscribed, but the maximum meshing portion (the most meshed portion of the two external gears 18). The deep part) is 180 degrees out of phase.

  Each external gear 18 is formed with at least one, in this case, three crankshaft holes 21 penetrating in the axial direction, and the plurality of crankshaft holes 21 are arranged in the radial direction from the central axis of the external gear 18. Along with the distance, they are equidistant in the circumferential direction. Reference numeral 22 denotes a plurality of (as many as the crankshaft holes 21) through-holes formed in each external gear 18, and these through-holes 22 are arranged alternately with the crankshaft holes 21 in the circumferential direction and in the circumferential direction. They are arranged equidistantly. The through-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. End plate portions 26 and 27 to be presented, and a plurality (the same number as the through holes 22) of which one end is integrally connected to the end plate portion 26 and the other end is detachably connected to the end plate portion 27 by a plurality of bolts 28 It is comprised from the pillar part 29. FIG. The column portion 29 that connects the end plate portions 26 and 27 extends in the axial direction, and is inserted (freely fitted) into the through hole 22 of the external gear 18 while maintaining a slight gap.

  31 is a bearing interposed between the outer periphery of the support body 25, specifically, 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 the internal gear 15 is supported by these bearings 31. The body 25 is rotatably supported. Reference numeral 35 denotes at least one (same number as the crankshaft hole 21) crankshafts arranged at an equal angle in the circumferential direction. These crankshafts 35 are tapered roller bearings 36 fitted on one end in the axial direction. And it is rotatably supported by the support body 25, specifically the end plate portions 26 and 27, by a tapered roller bearing 37 fitted on the other end portion in the axial direction.

  The crankshaft 35 has two eccentric cams 38 that are eccentric by an equal distance from the central axis of the crankshaft 35 at the center in the axial direction, and these eccentric cams 38 are out of phase with each other by 180 degrees. Here, the eccentric cam 38 of the crankshaft 35 is loosely fitted in the crankshaft hole 21 of the external gear 18, and a needle roller bearing 39 is interposed between them, and as a result, the outer cam 38 is inserted. Relative rotation between the toothed gear 18 and the crankshaft 35 is allowed. 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. .

  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 cam 38 of the crankshaft 35 is moved into the crankshaft hole 21 of the external gear 18. As a result, the external gear 18 rotates eccentrically. At this time, the driving force in the direction of the action line S is applied from the external teeth 19 to the corresponding internal teeth (pins) 14 at the contact points between the internal teeth (pins) 14 and the external teeth 19 that are engaged with each other. Is done.

  Here, the action line S of the reaction force K of each driving component described above is located on a line perpendicular to the tooth surface at the contact point, as shown in FIG. Thus, since the internal teeth (pins) 14 have a cylindrical shape and the external teeth 19 are formed of a trochoidal tooth profile, they are set (intersected) at one point on the external gear 18, that is, at a set point C. Then, the sum of the tangential components of each driving component is given to the internal gear 15 as a rotational driving force.

  Here, when the set point C is located between the outer end passing circle G and the inner end passing circle N as described in the background art (see FIG. 6), the bridge portion 05 having low rigidity is formed. On the other hand, since the reaction force K of the drive component force of a part (near the maximum meshing portion) acts in a direction substantially orthogonal to the extending direction of the bridge portion 05, the external teeth 01 in the vicinity of the bridge portion 05 and the bridge portion 05 are The outer teeth 01 and the inner teeth (pins) 02 come into contact with each other due to elastic deformation, and the tooth surface life of the outer teeth 01 is shortened.

  However, in this embodiment, the above-mentioned set point C is moved radially outward from the conventional position, and is positioned radially outward from the outer end passing circle G. As a result, when the set point C is positioned on a radial line passing through the center of the through hole 22 as shown in FIG. It is inclined to the tangential direction side from the past, and comes closer to the extending direction of the bridge portion 18a. As a result, elastic deformation of the thin and low-rigidity bridge portion 18a and the external teeth 19 in the vicinity of the bridge portion 18a is suppressed, and the tooth surface life of the external teeth 19 is extended.

  Moreover, when the set point C is located radially outside the outer end passing circle G as described above, the tangential direction component of the reaction force K is not a hollow portion of the through-hole 22 but has high tangential rigidity. Since the bridge portion 18a receives the deformation, the deformation of the through hole 22 can be suppressed. However, when the set point C is located radially outward from the pin circle P passing through the centers of all the pins constituting the inner tooth 14, a sharp portion is formed on the tooth surface of the outer tooth 19, and therefore the set point C Must be located between the outer end passing circle G and the pin circle P.

  Here, the radial distance L from the center O of the internal gear 15 to the set point C is equal to the eccentric amount H of the external gear 18 with respect to the internal gear 15 and the internal teeth (pins) 14 of the internal gear 15. Since the distance L can be expressed by multiplying by the number of teeth Z, in order to make the distance L larger than the conventional distance L shown in FIG. Good. In this embodiment, the amount of eccentricity H is increased in order to increase the distance L. However, in order to further increase the amount of eccentricity H, the outer diameter of the inner teeth (pins) 14 is smaller than the conventional one. It is said.

  Here, the value (L / Q) of the radial distance L and the radius Q of the pin circle P is preferably in the range of 0.86 to 1.00. The reason is that when the value of the ratio L / Q is 0.86 or more, as is apparent from FIG. 5, the load ratio becomes substantially constant, and in order to obtain the same torque, the load related to torque transmission applied to the external teeth 19 ( The tangential direction component of the drive component) is almost constant and minimum, but if it is less than O.86, the change in the load ratio increases, and the load related to torque transmission applied to the external teeth 19 increases. On the other hand, when the value of the ratio L / Q exceeds 1.00, a sharp portion is generated on the tooth surface when the external tooth 19 is created.

  Here, the above-mentioned graph is obtained by performing simulation in the following specifications. That is, the number of teeth Z (number) of the internal teeth (pins) of each planetary gear device is 40, the diameter of the internal teeth (pins) is 10 mm, the radius Q of the pin circle P is 120 mm, and the number of external teeth is 39. On the other hand, the value of L / Q was changed in the range of 0.5 to 1.0, and the tangential direction component of the resultant force of the reaction force K acting on the gathering point C was obtained. Here, in FIG. 5, the tangential direction component when the value of L / Q is 0.75 is displayed as a graph with the load ratio being index 1.

  As described above, when the outer diameter of the inner teeth (pins) 14 is smaller than that of the conventional one and the amount of eccentricity H is larger than that of the conventional one, the outer teeth 19 whose both tooth surfaces are in contact with the inner teeth (pins) 14 are larger. Both tooth thickness and tooth height increase. However, since the inner periphery of the rotating case 12 is generally located substantially on the pin circle P, the outer teeth 19 interfere with the inner periphery of the rotating case 12 when the outer teeth 19 increase in size. For this reason, in this embodiment, the tooth tip portion of the external tooth 19 (the part indicated by the phantom line in FIG. 3) is excised by a predetermined amount along a circle whose center of curvature is the center of the external gear 18, and the external tooth Interference between 19 and the inner periphery of the rotating case 12 is prevented. The above-mentioned interference is prevented by cutting the inner periphery of the rotating case 12 between the adjacent inner teeth (pins) 14 by a predetermined depth instead of cutting the tip portion of the external tooth 19. May be.

  Here, the above-mentioned set point C is preferably located between the root circle M passing through the roots of all the external teeth 19 and the outer end passing circle G. The reason is that when the set point C is located between the pin circle P and the root circle M, a part of the reaction force K extends almost tangentially to the external gear 18, and as a result, The external teeth 19 may be bent and deformed by such a reaction force K, but if the set point C is positioned between the root circle M and the outer end passing circle G as described above, This is because the situation can be prevented.

  In addition, when the tooth tip part of each external tooth 19 is excised as described above, the internal teeth (pins) 14 and the external teeth 19 are engaged with only a part thereof, here only about 3/4. The remaining approximately 1/4 of the internal teeth (pins) 14 do not come into contact with the external teeth 19 and try to come out of the pin groove 13. For this reason, in this embodiment, insertion holes 31b into which both end portions of the inner teeth (pins) 14 are inserted are formed on the inner end surface of the outer race 31a of the bearing 31, whereby the inner teeth (pins) 14 are formed. The pin groove 13 is prevented from coming out. At this time, the driving force is transmitted from the outer teeth 19 to the inner teeth (pins) 14 in a range of about 3/8.

  The aforementioned insertion hole 31b constitutes a restricting means 43 that prevents the internal teeth (pins) 14 that are not in contact with the external teeth 19 from coming out of the pin grooves 13 as a whole. As the aforementioned restricting means 43, instead of the insertion hole 31b, a circumferential groove formed on the inner end surface of the outer race 31a and having the same width as the diameter of the inner teeth (pins) 14 can be used. One pin holding ring that is arranged between the two external gears 18 and whose outer periphery contacts all the internal teeth (pins) 14 is used, or is further arranged between the bearing 31 and the external gear 18. It is also possible to use two pin pressing rings formed with holes and circumferential grooves into which both end portions of the internal teeth (pins) 14 are inserted.

Next, the operation of the first embodiment of the present invention will be described.
Now, it is assumed that the drive motor operates and the crankshaft 35 is rotating around the center axis in the same direction and at the same speed. At this time, the eccentric cam 38 of the crankshaft 35 rotates eccentrically in the crankshaft hole 21 of the external gear 18 to rotate the external gear 18 eccentrically, and the number of teeth of the external teeth 19 of the external gear 18 is increased. Is one less than the number of internal teeth (pins) 14, the rotating case 12, the robot arm, and the like rotate at a low speed due to the eccentric oscillation rotation of the external gear 18.

  Here, the set point C where the action lines S of the driving component force (reaction force K) applied from the external teeth 19 of the external gear 18 to the corresponding internal teeth (pins) 14 overlap is defined as all internal teeth. The pin C is located between the pin circle P passing through the center of the pin 14 and the outer end passing circle G passing through the radially outer ends of all the through holes 22. , The line of action S of any reaction force K is inclined to the tangential side with respect to the through-hole 22 in the conventional manner, whereby the bridge portion 18a and the bridge portion 18a Elastic deformation of the adjacent external teeth 19 is suppressed.

    In the above-described embodiment, a plurality (three) of the crankshaft holes 21 are formed in the external gear 18, and the crankshafts 35 that rotate at the same speed in the same direction are inserted into the crankshaft holes 21, respectively. Although the external gear 18 is rotated eccentrically and rotated, in the present invention, one crankshaft is inserted into one crankshaft hole formed on the central shaft of the external gear 18, and the crank The external gear may be rotated eccentrically by rotating the shaft. In this case, the pillar portion of the support needs to be in line contact with the inner periphery of the through hole.

  In the above-described embodiment, the support 25 is fixed and the internal gear 15 is rotated at a low speed. However, in the present invention, the internal gear is fixed and the support is rotated at a low speed. Also good. Furthermore, in the present invention, a spur gear reducer having a reduction ratio smaller than 1/7 (close to 1/1) may be provided in the preceding stage of the planetary gear unit 11 to reduce the speed in two stages. If it does in this way, the gear apparatus of a high reduction ratio with a high natural frequency can be obtained.

  The present invention can be applied to an eccentric oscillating planetary gear device in which an external gear meshing with an internal gear is eccentrically oscillated by a crankshaft.

It is side surface sectional drawing which shows Example 1 of this invention. It is II sectional view taken on the line of FIG. It is sectional drawing similar to FIG. 2 which shows the meshing state of an internal tooth and an external tooth. FIG. 5 is an explanatory diagram for explaining a state where action lines S of driving component force (reaction force K) are gathered at a set point C; It is a graph which shows the relationship between a load ratio and the value of L / Q. FIG. 5 is an explanatory diagram for explaining a state where action lines S of driving component force (reaction force K) described in the background art are gathered at a set point C;

Explanation of symbols

11 ... Planetary gear unit 14 ... Internal teeth (pin)
15 ... Internal gear 18 ... External gear
19 ... External teeth 21 ... Crankshaft hole
22 ... through hole 25 ... support
29 ... pillar 35 ... crankshaft P ... pin circle G ... outer end passing circle M ... root circle C ... set point S ... action line K ... reaction force of driving component force

Claims (3)

    An internal gear provided with internal teeth composed of a large number of cylindrical pins on the inner periphery, at least one crankshaft hole and a plurality of through holes are formed, and has a trochoidal tooth shape on the outer periphery and meshes with the internal teeth An external gear having a large number of external teeth, a crankshaft that is inserted into each crankshaft hole and rotates eccentrically by rotating, and supports the crankshaft rotatably, and in each through hole In an eccentric oscillating planetary gear device including a support body having a plurality of inserted column portions, an action line S of a reaction force K of a driving component force applied from each external tooth to a corresponding internal tooth is obtained. The overlapping set point C is positioned between the pin circle P passing through the centers of all the pins constituting the inner teeth and the outer end passing circle G passing through the radially outer ends of all the through holes. An eccentric oscillating planetary gear device characterized by that.     2. The eccentric oscillating planetary gear device according to claim 1, wherein the set point C is positioned between a root circle M passing through the roots of all external teeth and the outer end passing circle G.     The eccentric oscillating planetary gear device according to claim 1 or 2, wherein the number of teeth of the external teeth is one less than the number of teeth of the internal teeth.

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