CN106402285B

CN106402285B - Eccentric swinging type planetary gear speed reducer capable of increasing output torque

Info

Publication number: CN106402285B
Application number: CN201611006452.6A
Authority: CN
Inventors: 李宗翰
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-11-16
Filing date: 2016-11-16
Publication date: 2020-09-04
Anticipated expiration: 2036-11-16
Also published as: CN106402285A

Abstract

The invention discloses an eccentric oscillating type planetary gear speed reducer capable of increasing output torque, which comprises an internal gear, an external gear, a crankshaft and a support body, wherein the external gear is provided with at least one crankshaft hole and a plurality of through holes, the periphery of the external gear is provided with external teeth which are mutually meshed with the internal teeth of the internal gear and have 1 less tooth number than the internal teeth; the internal gear is provided with the internal tooth that a plurality of oval column rollers constitute with certain pitch P at the inner periphery, and makes and constitute internal tooth thickness S and divide the ratio of the certain pitch P of internal tooth to reduce to the addendum of external tooth to the radial direction outside and exceed the internal tooth root to at least the external tooth of the part of the internal tooth root of excision excess internal gear, avoid the interference of external tooth and column oval internal tooth root with this. According to the invention, the output torque of the eccentric swinging type planetary gear speed reducer is further increased by innovatively designing a novel internal tooth profile, so that the transmission efficiency is improved; and the output torque can be increased without increasing the size.

Description

Eccentric swinging type planetary gear speed reducer capable of increasing output torque

Technical Field

The invention belongs to the field of RV reducers, and particularly relates to an eccentric swinging type planetary gear speed reducer capable of increasing output torque.

Background

As conventional eccentric oscillating planetary gear reduction devices, there are known, for example, those described in patent documents such as patent document 1 — CN1831372A, patent document 2 — CN10128082A, patent document 3 — CN104633013A, patent document 4 — CN104565217A, patent document 5 — CN1409029A, patent document 6 — CN101263319A, patent document 7 — CN103968008A, patent document 8 — CN105605159A, patent document 9 — CN1120634A, and patent document 10 — CN105020344A, which are published domestically; all adopt the cycloidal pinwheel type structural style with small tooth difference.

At present, the robot speed reducer basically takes an RV speed reducer (cycloid pinwheel structure) as a main part, and is widely applied to the field of industrial robots and the field of precision machinery due to the advantages of small volume, large torque, high positioning precision, small vibration, impact resistance and the like, but the speed reducer is complex in design and manufacture, high in difficulty, high in machining and mounting precision requirements, monopolized by Japanese companies in core technology, insubstantial breakthrough is not made in design and manufacture of the high-precision speed reducer of the robot at home, and a product with independent intellectual property rights is not available; severely restricting and hindering the development of domestic industrial robots.

The current reduction ratio speed reducer in the market generally adopts cycloid pin wheel type structure, for example: the RV speed reducer, the FA speed reducer precision speed reducer, the universal cycloidal pin gear speed reducer and the like in Japan all adopt cycloidal pin gear structural forms; however, the cycloid pin gear type speed reducer has a drawback that torque cannot be sufficiently increased. For example, in a conventional cycloidal-pin gear type reduction gear, the basic structural principle of the device described in the above-mentioned published domestic patent documents is known as described in the bii device. The BI device includes: an internal gear having internal teeth formed of a plurality of cylindrical rollers provided at a predetermined pitch on an inner periphery thereof; an external gear formed with a central crank shaft through hole and a plurality of pin through holes, having a trochoid tooth form on an outer periphery thereof, engaged with the internal gear and having a smaller number of teeth than the internal gear by one, and having a center thereof spaced from a center of the internal gear by a constant distance; a crank shaft inserted into the crank shaft hole; the pin body is inserted into each pin through hole; eccentrically oscillating the external gear by rotation; and a plurality of pin bodies movably and contactingly inserted into the respective through holes. The device is shown in fig. 14 and 15: the eccentricity e between the external gear 01 and the internal gear 03 is set, and the external teeth 02 of the external gear 01 in contact with each other apply a driving component force in the direction perpendicular to the tooth surface to the internal teeth (cylinders) 04 of the internal gear 03 at the contact points, and also apply a reaction force K of the driving component force to the external teeth 02 as the reaction internal teeth (cylinders) 04. As shown in fig. 16, the lines of action D of the reaction forces K of the driving component force applied to the corresponding internal teeth (cylinders) 04 by each external tooth 01 overlap and converge at a point C, and the point C at which the distance from the radially outer side of the center of the internal gear is denoted as L; for example, when the number of teeth in the internal gear is constant, the number and the distribution position of the pin teeth are constant, and the eccentric amount of the internal gear in the external gear is also constant, the distance from the position of the collection point C to the central radius direction of the internal gear is fixed, and the movement of the collection point C to the outer side of the central radius direction of the internal gear is limited; the increase of the output torque is restricted.

Disclosure of Invention

The invention aims to provide an eccentric swinging type planetary gear speed reducer capable of increasing output torque, which further increases the output torque of the eccentric swinging type planetary gear speed reducer and improves the transmission efficiency by innovatively designing a novel internal tooth profile; and the output torque can be increased without increasing the size.

The technical scheme adopted by the invention is as follows: an eccentric oscillating type planetary gear speed reducer capable of increasing output torque, comprising an internal gear, an external gear, a crank shaft and a support body, wherein the external gear is provided with at least one crank shaft hole and a plurality of through holes, the periphery of the external gear is provided with external teeth which are mutually meshed with internal teeth of the internal gear and have 1 less tooth number than the internal teeth; the crank shafts are inserted into the crank shaft holes, the external gear swings eccentrically by synchronously rotating the crank shafts, and the support bodies are cylindrical bodies inserted into the through holes and used for rotatably supporting the crank shafts; the internal gear is provided with internal teeth consisting of a plurality of elliptic cylindrical rollers at a certain pitch P on the inner periphery, the ratio of the tooth thickness S of the internal teeth divided by the certain pitch P of the internal teeth is reduced to the extent that the tooth tops of the external teeth exceed the tooth roots of the internal teeth in the radial direction, and the external teeth of the parts exceeding the tooth roots of the internal gear are at least cut off, so that the interference between the external teeth and the cylindrical elliptic internal tooth roots is avoided; when the external teeth are cut along a line V connecting

inflection points

04d and 04e of both tooth surfaces, a distance A between the

inflection points

04d and 04e is larger than a position determined by subtracting a root circle radius R of the internal gear from a tooth crest circle radius T of the external teeth and adding an eccentric amount e of the external gear to the internal gear.

Further optimize, make and constitute the internal tooth thickness S and divide the specific value of certain tooth pitch P of internal tooth and reduce to the addendum of external tooth to the radial direction outside and exceed the internal tooth root to at least, excise the internal tooth root of internal gear between the adjacent internal tooth, by the partial depth volume of external tooth addendum exceeding the internal tooth root of internal gear, with this interference of avoiding external tooth and column ellipse internal tooth root.

Further preferably, when a radius of a root circle of all the columnar elliptic internal teeth constituting the internal teeth is set to R, and an action line D from a normal direction of an internal tooth profile tooth surface of the internal gear to a driving component force K' applied to the corresponding internal teeth by the external teeth is converged to an equivalent torque action point C generated on a moment arm axis OL, and a distance OC of a point C in a radial direction is set to Q, the point C is a distance Q in the radial direction within a range of 0.85 to 1.00 times the radius R of the root circle.

Compared with the prior art, the invention at least has the following advantages and beneficial effects:

according to the eccentric oscillating type planetary gear speed reducer, the novel internal tooth profile is innovatively designed, so that the output torque of the eccentric oscillating type planetary gear speed reducer is further increased, and the transmission efficiency is improved; and the output torque can be increased without increasing the size.

The invention develops and designs the technology and the product of the national independent knowledge brand by effectively implementing and promoting the technical progress of the small tooth difference precision speed reducer; the technology of the invention breaks through the long-term technical monopoly abroad, establishes a high-precision speed reducer core technology research and development system for the robot with completely independent intellectual property rights, improves the core competitiveness of China in the aspect of precision speed reducers, and promotes the development of China precision speed reducers and the robot industry.

Drawings

FIG. l is a side sectional view of embodiment l of the present invention;

FIG. 2 is a sectional view taken along line I-I of FIG. l;

fig. 3 is an explanatory diagram of a reaction force K acting on the external teeth and its action line Q;

FIG. 4 is an enlarged view of the portion U of FIG. 3;

FIG. 5 is a side sectional view of embodiment 3 of the present invention;

FIG. 6 is a sectional view taken along line II-II of FIG. 5

Fig. 7 is a sectional view showing a meshing state of internal teeth and external teeth;

fig. 8 is an explanatory diagram illustrating a state where the line of action D of the driving force component (reaction force K) intersects the equivalent torque point C on the OL moment arm;

FIG. 9 is a side sectional view of embodiment 4 of the present invention;

FIG. 10 is a sectional view in elevation III-III of FIG. l 1;

fig. 11 is a partially enlarged sectional view of a U region in a meshed state of internal teeth and external teeth;

FIG. 12 is an explanatory view of a driving force component K of the inner teeth and its line of action D in a cross-sectional view of a tooth difference cycloid pin gear;

fig. 13 is an explanatory view showing a driving force component K of the elliptic cylindrical internal teeth of the present invention and a line of action D thereof;

FIG. 14 is a side sectional view of an example of the background art;

FIG. 15 is a cross-sectional view of an example of the background art;

FIG. 16 is a diagram illustrating a state where the line of action D of the driving force component (reaction force K) described in the background of the specification intersects the torque point C on the OL moment arm;

FIG. 17 is a force analysis diagram of the active working engagement region.

Detailed Description

In order that the present invention may be more fully understood, reference will now be made in detail to the following examples.

Example 1:

in fig. l and 2, a planetary gear reduction apparatus ai is an approximately cylindrical rotating casing 02 attached to an arm, a hand, or the like of a robot not shown in the drawings, and is an elliptical cylindrical internal gear reduction apparatus for a robot or the like, and a plurality of cylindrical internal teeth 05 (a part of an ellipse) having an elliptical cross section at the center in the axial direction are formed on the inner periphery of the rotating casing 02, and the elliptical cylindrical internal teeth 05 extend in the axial direction and are distributed at equal intervals in the circumferential direction, and are arranged at a constant pitch p. The rotary case 02 and the elliptic columnar internal teeth 05 are integrated to constitute an internal gear 01. The certain pitch P is as follows: the circumferential length of all the inner tooth root circles R constituting the elliptical columnar inner teeth 05 is divided by the number of the elliptical columnar inner teeth 05, in other words, the arc length of the root circle R connecting any adjacent 2 elliptical columnar inner teeth 05 by an arc line segment. The tooth height h is as follows: the closest distance from the tooth top of the internal gear to the circumference of the tooth bottom of the internal gear.

The number of the elliptic columnar internal teeth 05 is generally about 16 to 150, but preferably in the range of 30 to 100. The reason for this is that if the number of teeth of the elliptical columnar internal teeth 05 is set within the above range, a spur gear reduction mechanism having a reduction ratio of 3/1 to 1/7 is provided at the previous stage where the external gear 14 described later meshes with the internal gear 01, and the reduction ratios of the previous stage and the next stage are flexibly combined, a high reduction ratio can be easily obtained, and a planetary gear reduction device having a high reduction ratio with a higher natural frequency can be configured.

A plurality of (2 in the figure) external-teeth gears 14 having a ring shape are housed in the internal gear 01 in parallel in the axial direction, and a plurality of external teeth 04 having a special trochoid tooth profile are formed on the outer periphery of each of the external-teeth gears 14. The number Z of the external teeth 04 of the external gear 14 is 1 less than the number of the elliptic columnar internal teeth 05 (the difference in the number of teeth is 1). In addition, while the external teeth 04 mesh with the elliptical columnar internal teeth 05 in a state where the external gear 14 is inscribed in the internal gear 01, the maximum meshing portion (deepest meshing portion) of the 2 external gears 14 is shifted in phase by 180 °.

At least one, in the figure, 3 crank shaft holes 15 penetrating in the axial direction are formed in each external gear 14, and these crank shaft holes 15 are equally spaced from the central axis of the external gear 14 in the radial direction and are equally spaced apart in the circumferential direction. The number 09 is a plurality of (3, the same as the number of the crank shaft holes 15) through holes formed in each external gear 14, and the through holes 09 are arranged in the circumferential direction so as to intersect with the crank shaft holes 15 and are arranged at equal angular intervals in the circumferential direction.

The number 07 is a number (3, the number is the same as the number of the through holes 09) of columnar bodies 11 which are movably mounted in a rotary housing 02 and are fixed to a support body holder of a robot member, and the support body 07 is constituted by a pair of approximately

annular end plates

08, 13 which are disposed at both outer sides in the axial direction of an external gear 14, and one end of which is integrally connected to the end plate 08, and the other end of which is detachably connected to the end plate 13 by a plurality of bolts 10. The columnar body 11 connecting the

end plates

08 and 13 is inserted (removably fitted) into the through hole 09 of the external gear l4 with a slight gap maintained therebetween, extending in the axial direction.

Reference numeral 03 denotes a pair of bearings attached to the support body 07, specifically, between the outer peripheries of the

end plates

08 and 13 and the inner peripheries of both ends in the axial direction of the rotary case 02, and the internal gear 01 is rotatably supported by the support body 07 through the bearings 03. The crank shafts 21 are at least one (3 as many as the crank shaft holes 15) arranged in a circumferential direction at equal angular intervals, and these crank shafts 21 are supported by the support body 07, specifically, the

end plates

08 and 13, so as to be rotatable by the tapered roller bearing 19 externally fitted to one end in the axial direction and the tapered roller bearing 19 externally fitted to the other end in the axial direction.

The crankshaft 21 has 2 eccentric camshafts 17 eccentric by an equal distance from the central axis of the crankshaft 21 at the center in the axial direction, and the phases of the eccentric camshafts 17 are shifted by 180 °. Here, the eccentric cam shafts 17 of the crank shaft 21 are movably fitted in the crank shaft holes 15 of the external gear l4 by needle roller bearings 18, respectively, and as a result, the external gear 14 and the crank shaft 21 are allowed to rotate relative to each other. An externally toothed gear 16 is fixed to one end of each crankshaft 21 in the axial direction, and the externally toothed gear 16 meshes with an externally toothed gear 12 provided at one end of an input shaft 20 in the drawing.

When the motor drives the input shaft 20, the external gear 12 is rotated, and at the same time, the external gear 16 is driven to rotate, and the crankshaft 21 is rotated about its central axis, so that the eccentric cam shaft 17 of the crankshaft 21 eccentrically rotates in the crank shaft hole 15 of the external gear 14, and the external gear 14 eccentrically swings in the arrow direction. At this time, as shown in fig. 2, 3, and 4, at the contact points between the elliptical columnar internal teeth 05 and the external teeth 04 which are engaged with each other, a driving component force which is applied to the corresponding elliptical columnar internal teeth 05 by the external teeth 04 in the direction of the tooth surface normal line D of action of the internal teeth 05 acts on each of the external teeth 04, and as a reaction force thereof, a reaction force K which is applied to the elliptical columnar internal teeth 05 by the external teeth 04 in the direction of the tooth surface normal line D of action of the internal teeth 05 acts on each of the external teeth 04.

The tooth height h of the elliptical columnar internal teeth 05 is set to half (S/2) the tooth thickness S, and the ratio B of the tooth thickness S of the elliptical columnar internal teeth 05 divided by the constant pitch P of the elliptical columnar internal teeth 05 is reduced such that the tooth crests 04B indicated by the imaginary line of the external teeth 04 exceed the radially outer side of the root circle R of the internal gear 01, and when the number of teeth of the elliptical columnar internal teeth 05 is 18, for example, the tooth thickness S of the elliptical columnar internal teeth 05 is conventionally set to about 0.55 and reduced to about 0.35, whereby the tooth thickness S of the elliptical columnar internal teeth 05 is made smaller than before, and the tooth roots 04a of the external teeth 04 of the external gear 14 are moved radially outward.

When the roots 04a of the external teeth 04 are moved radially outward as described above, the radial distance from the radially outer end of the through hole 09 to the roots 04a of the external teeth 04 increases, and the bending rigidity increases even if the thickness J of the bridge portion 23 is thicker than before, and as a result, the elastic deformation of the bridge portion 23 and the external teeth 04 due to the reaction force K is suppressed, and the tooth surface life of the external teeth 04 can be extended, and the natural frequency can be increased even in the presence of a torque load, and the vibration characteristics and controllability can be improved.

Here, when the tooth thickness S of the elliptic cylindrical internal teeth 05 is reduced as described above, the tooth thickness and the tooth height of the external teeth 04 in contact with two adjacent elliptic cylindrical internal teeth 05 (the front tooth surface and the rear tooth surface in the rotation direction) are increased, but if the ratio B is reduced as described above so that the tooth crest 04B exceeds the root circle radius direction outside of the internal tooth root 01a, the external teeth 04 with the increased tooth height interfere with the internal tooth root 01 a. For this reason, interference between the external teeth 04 and the internal tooth root 01a of the internal gear 01 is avoided by cutting off at least a portion of the external teeth 04 that exceeds the internal tooth root 01a of the internal gear 01.

Here, it is preferable that the cut-out position on the external teeth 04 of the external gear 14 is set from the external gear crest circle: the external gear is cut from the outer side to the inner side in the radial direction of the external gear, the cut amount is determined by subtracting the radius of the tooth top circle of the external gear from the radius of the root circle of the internal gear R and adding the eccentric amount e of the external gear to the internal gear, and the cut amount is slightly larger than the determined position amount. The reason for this is that, if this is done, the cut-out amount can be minimized, and the external teeth that contribute to the transmission torque can be retained as much as possible without cutting out, thereby suppressing the reduction in the transmission torque. Meanwhile, if a large sliding portion is formed when the external teeth 04 mesh with the elliptical columnar internal teeth 05 and a small sliding portion is left between the external teeth 04 and the elliptical columnar internal teeth 05, noise and heat generation can be reduced.

As described above, as the tooth root 04a of the external tooth 04 moves outward in the radial direction as the tooth thickness S decreases, there are three methods: one is a method of increasing the diameter of a root circle passing through all the roots 04a of the external gear 14 when the eccentricity e of the external gear 14 with respect to the internal gear 01 is constant; secondly, the tooth root circle is constant and is a fixed value, and the eccentricity Q is increased; third, the root circle and the eccentric amount e are increased simultaneously, but in example 1, the eccentric amount e is increased by keeping the root circle constant.

The following describes the operation of example 1 of the present invention.

Now, the drive motor operates, and the crank shaft 21 rotates. At this time, the eccentric cam shaft 17 of the crank shaft 21 eccentrically rotates in the crank shaft hole 15 of the external gear 14 to eccentrically swing the external gear 14, but the number of teeth of the external teeth 04 of the external gear 14 is smaller by 1 than the number of the elliptic columnar internal teeth 05, and therefore the rotating housing 02, the robot arm, and the like rotate at a low speed due to the eccentric swing rotation of the external gear 14.

Here, as described above, the ratio B of the thickness S of the elliptical columnar internal teeth 05 divided by the constant pitch P is decreased to such a degree that the tooth crests 04B of the external teeth 04 exceed the radially outer side of the root circle R of the internal gear 01, so that the thickness S of the elliptical columnar internal teeth 05 is smaller than before, and the tooth roots 04a of the external teeth 04 of the external gear 14 move radially outward, and as a result, the thickness g (minimum thickness) of the bridge portion 23 becomes thicker than before, and the bending rigidity becomes stronger.

This suppresses elastic deformation of the bridge portion 23 and the external teeth 04 due to the reaction force K of the driving component force, and can prolong the tooth surface life of the external teeth 04, increase the natural frequency, and improve the vibration characteristics and controllability. Here, if the above configuration is adopted, the external teeth 04 interfere with the internal tooth roots 01a of the internal gear 01, but such interference of the external teeth 04 with the internal tooth roots 01a of the internal gear 01 is avoided by cutting off at least a portion of the external teeth 04 that exceeds the tooth roots 01a of the internal tooth root circle R of the internal gear 01.

Example 2

In embodiment 2, instead of cutting off the external teeth 04 as in embodiment 1, it is preferable to cut off the internal tooth root (root circle R) of the internal gear 01 (rotating case 02) between the adjacent elliptical columnar internal teeth 05 and the internal tooth root inner circumference around each elliptical columnar internal tooth 05, and to cut off the elliptical columnar internal tooth 05 root at a depth position where the external teeth 04 extend beyond the internal tooth root circle R by an amount equal to or more, starting from the internal tooth root circle: the depth of the cut-off amount is determined by subtracting the radius R of the root circle of the internal teeth of the internal gear from the radius T of the gear top circle of the external teeth and adding the eccentric amount e of the internal gear of the external gear. The depth of the external teeth 04 from the internal tooth roots (01 a) is cut to a depth exceeding the internal tooth roots (01 a), and the cut depth is substantially equal to half the tooth thickness S of the elliptical columnar internal teeth 05, thereby avoiding interference between the external teeth 04 and the internal tooth roots 01a of the internal gear 01 (the rotating housing 02) after the cutting.

As a result, the outer end of each elliptical columnar internal tooth 05 in the root circle radial direction moves, the tooth root 01a of the internal tooth root circle R of the internal gear 01 after the cutting becomes large, the internal tooth height h becomes large, and the rotary housing 02 receives a component force acting in the internal tooth surface normal direction of the driving component force of each elliptical columnar internal tooth 05. At this time, since the internal tooth roots are deepened and enlarged, the external gear 01 can swing and move along a predetermined path, and interference between the external teeth 04 and the internal tooth roots 01a of the internal gear 01 (the rotary housing 02) after the cutting-out is avoided. Otherwise, the other structures and actions are the same as those of the above embodiment l.

In addition, in the above-described embodiment 1, a plurality of (3) crank shaft holes 15 are formed in the external gear 14, and the external gear 14 is eccentrically oscillated and rotated by inserting the crank shafts 21 rotating at the same speed in the same direction into the respective crank shaft holes 15, respectively, but in the present invention, the eccentric cams of 1 crank shaft may be inserted into one crank shaft hole formed on the central axis of the external gear 14, and the external gear may be eccentrically oscillated and rotated by the rotation of the crank shaft. At this time, the columnar body of the support body must be in line contact with the inner periphery of the through hole.

In embodiment 1, the supporter 07 is fixed and the ring gear 01 is rotated at a low speed, but in the present invention, the ring gear may be fixed and the supporter may be rotated at a low speed. In the planetary gear reduction unit a1 having the original diameter without reducing (proportionally) the tooth thickness S of the columnar internal teeth 05 constituting the ellipse, the external teeth 04 may be cut off at a position slightly higher than the 1/2 external tooth height on the outer side in the radial direction of the external gear, thereby reducing heat generation and noise while suppressing a reduction in transmission torque.

Example 3

In fig. 5, 6, and 7, a ii is an eccentric oscillating type planetary gear device used for a robot or the like, and the planetary gear reduction device ai has a substantially cylindrical rotating case 102 attached to an arm, a hand, or the like of the robot, which is not shown in the drawings, for example. A plurality of columnar internal teeth 105 having an elliptical cross section at the center in the axial direction are formed on the inner periphery of the rotary case 102, and the columnar internal teeth 105 extend in the axial direction and are arranged at equal intervals in the circumferential direction. These elliptic columnar internal teeth 105 are thus provided on the inner periphery of the rotary case 102 at equal distances in the circumferential direction. The above-described rotary case 102 and the elliptical columnar internal teeth 105 are integrated to form an internal gear 101 in which a plurality of elliptical columnar internal teeth 105 are provided on the inner periphery. Here, the number of the elliptical columnar internal teeth 105 is about 16 to 150, but preferably in the range of 30 to 100. The reason for this is that if the number of the elliptical columnar internal teeth 105 is set within the above range, and the

external gears

116 and 112 described later are assembled, a desired speed ratio can be easily obtained, and the natural frequency can be increased, thereby obtaining a planetary gear reduction device with a high reduction ratio.

A plurality of (2 here) external gears 114 having a ring shape are accommodated in the internal gear 101 in parallel in the axial direction, and the external teeth 104 are formed by the outer peripheries of the external gears 114 each having a special trochoid tooth profile, specifically, a tooth profile obtained by combining an internal and external trochoid circle. The external teeth 104 of the external gear 114 have 1 smaller number of teeth (1 tooth number difference) than the elliptical columnar internal teeth 105. In this way, the difference in the number of teeth between the elliptical columnar internal teeth 105 and the external teeth 104 is l, and thus a high reduction ratio can be easily achieved as compared with a value in which the difference in the number of teeth is 2 or more, and the processing cost can be reduced.

Here, the external teeth 104 mesh with the elliptical columnar internal teeth 105 in a state where the external gear 114 is inscribed in the internal gear 101, but the phase of the maximum meshing portion (the portion where the meshing is deepest) of the 2 external gears 114 is shifted by 180 °.

At least one, here 3 crank shaft holes 115 penetrating in the axial direction are formed in each external gear 114, and these crank shaft holes 115 are equally spaced from the central axis of the external gear 114 in the radial direction and equally spaced apart in the circumferential direction. The external gear 114 has a plurality of through holes 109 (the number of which is equal to that of the crank shaft holes 115), and the through holes 109 are circumferentially arranged to intersect with the crank shaft holes 115 and circumferentially spaced apart by equal distances.

The support 107 is a support body which is movably mounted in the rotary housing 102 and is attached to a fixed robot part (not shown), and the support body 107 is composed of a pair of

annular end posts

108 and 113 disposed on both outer sides in the axial direction of the external gear 114, and a plurality of (the same number as the number of through holes 109) columnar bodies 111 having one end integrally connected to the end post 108 and the other end detachably connected to the end post 113 by a plurality of bolts 110. The columnar body 111 connecting the end posts 108 and 113 extends in the axial direction, and is inserted (movably fitted) into the through hole 109 of the external gear 114 with some clearance kept therebetween

103 is a bearing installed between the support body l07 and the housing 102, and specifically includes: between the outer peripheries of the

end plates

108, 113 and the inner peripheries of both ends in the axial direction of the rotary case 102, the pair of bearings 103 rotatably support the internal gear 101 on the support body 107 by the pair of bearings 103. The crank shafts 121 are at least one (the same number as the crank shaft holes 115) | crank shafts disposed at equal angular intervals in the circumferential direction, and these crank shafts 121 are supported by the support body 107, specifically, the

end pillars

108, 113, rotatably by means of tapered roller bearings 119 mounted on one end in the axial direction thereof and tapered roller bearings 119 mounted on the other end in the axial direction thereof.

The crank shaft 121 has 2 eccentric cam shafts 117 at the center in the axial direction thereof, which are eccentric at equal distances from the center axis of the crank shaft 121, and the eccentric cam shafts 117 are shifted in phase by 180 ° from each other. Here, the eccentric cam shafts 117 of the crank shafts 121 are respectively movably fitted in the crank shaft holes 101 of the external gear 114, and needle roller bearings 114 are installed therebetween, with the result that the external gear 114 and the crank shafts 121 are allowed to rotate relatively. An external gear 116 is fixed to one end of each crank shaft 121 in the axial direction, and the external gear 116 meshes with an external gear 112 provided at one end of an input shaft 120, which is driven by a motor.

When the drive motor is operated to rotate the external gear 116; while driving the crank shaft 121 to rotate about its central axis, as a result, the eccentric cam 117 of the crank shaft 121 eccentrically rotates within the crank shaft hole 115 of the external gear 114, causing the external gear 114 to eccentrically oscillate and rotate. At this time, a driving component force in the direction of the normal line of action D of the internal tooth flank, which is applied to the corresponding elliptical columnar internal teeth 105 by the external teeth 104, acts on the contact points between the meshing linear columnar internal teeth 105 and the external teeth 104.

Here, the lines of action D of the reaction forces K of the respective driving component forces are on a line perpendicular to the tooth surface on which the contact points are located as shown in fig. 12, but these lines of action D converge on the torque action point C equivalent to the moment arm axis OL generated in the external gear 114 because the elliptic cylindrical internal teeth 105 are elliptic cylindrical and the external teeth 104 are formed of a special cycloid tooth profile as described above. Then, an equivalent resultant force of the tangential direction component forces of the above-described respective driving component forces acts on the ring gear 101 as a rotational driving force.

However, in embodiment 3, the equivalent torque acting point C generated on the arm axis OL is moved radially outward from the conventional one and is located radially outward from the outer end passing circle G. Accordingly, when the equivalent torque acting point C generated at the moment arm axis OL is located on the radial line passing through the center of the through hole 109 as shown in fig. 8, the acting lines D of all the reaction forces K are inclined more tangentially with respect to the through hole 109 than before, and are closer to the extending direction of the bridge portion 123. As a result, elastic deformation of the thin-walled low-rigidity bridge portion 123 and the external teeth 104 near the bridge portion 123 is suppressed, and the tooth surface life of the external teeth 104 is extended.

Further, when the equivalent torque acting point C generated so as to converge on the arm axis OL is located radially outward of the outer end passing circle G as described above, the bridge portion 123 having high rigidity in the tangential direction receives the component force in the tangential direction of the reaction force K, not the hollow portion of the through hole 109, and therefore, the deformation of the through hole 109 can be suppressed. However, when the convergence point C is located on the radially outer side of all the root circles R constituting the elliptic cylindrical internal teeth 105, a sharp portion is generated on the tooth surface of the outer tooth 104, and therefore the equivalent torque application point C generated on the arm axis OL must be located between the outer end passing circle G and the root circle R.

Since the distance Q in the radial direction from the center O of the internal gear 101 to the equivalent torque acting point C generated on the arm axis OL can be represented by multiplying the eccentric amount e of the external gear 114 with respect to the internal gear 101 by the number Z of internal teeth 105 of the internal gear 101, one or both of the eccentric amount e and the number of teeth can be made larger than the conventional distance Q shown in fig. 16. In example 3, the eccentric amount e is increased to increase the distance Q, but the tooth thickness S of the internal teeth 105 is made smaller than that of the conventional art to further increase the eccentric amount e. Here, the ratio (L/R) of the radial distance Q to the radius R of the root circle R is preferably in the range of 0.85 to l.00.

When the radius of all inner tooth root circles passing through the columnar elliptic inner teeth is R and the number of teeth of the inner teeth is Z, the tooth thickness of the inner teeth is within the range of 2Rsin (pi/2Z) ± emm. When the thickness of the internal teeth 105 is made thinner than the conventional one and the eccentricity e is made larger than the conventional one, the external teeth 104, both tooth surfaces of which are in contact with the internal teeth 105, become thicker, that is, both the thickness and the height of the teeth become larger. However, since the internal tooth root circle of the rotary case 102 is generally located substantially on the internal tooth root circle R, if the external teeth 104 are enlarged, the external teeth 104 interfere with the internal tooth roots of the rotary case 102. Therefore, in embodiment 3, the external teeth are cut out by a predetermined amount along a circle having the center of curvature of the external gear 114 as the center. The tooth tips (portions indicated by imaginary broken lines in fig. 7) of the outer teeth 104 prevent the outer teeth 104 from interfering with the inner tooth tips of the rotary case 102. The interference can be prevented by cutting off the inner tooth roots of the rotating case 102 between the adjacent inner teeth 105 to a predetermined depth.

Also, in this embodiment 3, the pair of bearings 103 is mounted on the support body 107 to rotatably support the inner shell 102, specifically: the bearing inner ring 103b of one bearing 103 is arranged on the end column part 113 of the support, the bearing outer ring 103a is arranged at one end of the inner gear shell 102, the bearing inner ring 103a of the other bearing 103 is arranged on the end column part 108, the bearing outer ring 103a is arranged on the inner gear shell 102, and the

end column parts

108 and 113 are integrated through a fastening screw 110; the pair of bearings 103 is configured to rotatably support the inner gear case 102 on a support body 107.

The operation of example 3 of the present invention will be described.

Now, the driving motor operates, and the crank shaft 121 rotates in the same direction and at the same speed about its central axis. At this time, the eccentric cam shaft 117 of the crank shaft 121 eccentrically rotates in the crank shaft hole 115 of the external gear 114 to eccentrically oscillate the external gear 114, but the external teeth 104 of the external gear 114 have 1 fewer teeth than the internal teeth 105, and therefore the rotating case 102 and the arm or the like attached thereto of the robot rotate at a low speed due to the eccentric oscillation rotation of the external gear 114.

Here, since the equivalent torque acting point C generated on the arm axis OL where the lines of action D of the driving component force (reaction force K) applied to the corresponding internal teeth 105 by the respective external teeth 104 of the external gear 114 overlap is located between the root circle R passing through all the internal teeth 105 and the outer end transit circle G passing through the radially outer end of all the through holes 109, when the equivalent torque acting point C generated on the arm axis OL is located on the radially line passing through the center of the through holes 109, the lines of action D of all the reaction forces K are inclined to the tangential direction side with respect to the through holes 109 than before, and elastic deformation of the bridge portion 123 and the external teeth 104 in the vicinity of the bridge portion 123 is suppressed.

In embodiment 3, a plurality of (3) crank shaft holes 115 are formed in the external gear 114, and the crankshafts 121 that rotate at a constant speed in the same direction are inserted into the respective crank shaft holes 115 to eccentrically oscillate and rotate the external gear 114, or one crankshaft may be inserted into 1 crank shaft hole formed in the central axis of the external gear 114 to eccentrically oscillate and rotate the external gear by the rotation of the crankshaft. In this case, the columnar body of the support must be in line contact with the inner periphery of the through hole.

In embodiment 3, the supporter 107 is fixed and the ring gear 101 is rotated at a low speed, or the ring gear may be fixed and the supporter may be rotated at a low speed. Further, a spur gear reduction mechanism may be provided at the stage before the planetary gear reduction device a11 to perform 2-stage reduction. Thus, a high reduction ratio gear device having a high natural frequency can be obtained.

Example 4

In fig. 9, 10, and 11, a iii is an eccentric oscillating planetary gear reduction device for a robot or the like, which has a substantially cylindrical rotation case 202 attached to a robot arm, hand, or the like, which is not shown in the drawings, for example. A plurality of columnar internal teeth having an elliptical cross section at the center in the axial direction are formed on the inner periphery of the rotary case 202, and the columnar internal teeth 202 of the elliptical shape extend in the axial direction and are arranged at equal intervals in the circumferential direction.

Reference numeral 205 denotes an internal tooth formed of a plurality of elliptic columnar spur teeth, and the internal teeth 205 are provided at equal intervals in the circumferential direction on the inner periphery of the rotary case 202. The rotating case 202 and the internal teeth 205 are integrated to form the internal gear 201. Here, the internal teeth 205 are arranged about 16 to 150, but preferably in the range of 30 to 100. The reason for this is that if the number of internal teeth 205 is within the above range, a single-stage spur gear reduction mechanism is provided at the previous stage where the external gear 214 described later meshes with the internal gear 201, and a combination of the reduction ratios of the previous and subsequent stages makes it possible to easily obtain a high reduction ratio, and also to obtain a planetary gear reduction device having a high reduction ratio while increasing the natural frequency.

A plurality of (2 here) external-tooth gears 214 having a ring shape are housed in the internal gear 201 in parallel in the axial direction, and a plurality of external teeth 204 each having a special trochoid tooth profile, specifically, a compound trochoid-epicycloidal tooth profile are formed on the outer periphery of each of the external-tooth gears 214. The number of teeth of the outer teeth 204 of the outer gear 214 is smaller than that of the inner teeth 205 by 1 (the difference in the number of teeth is 1). The reason why the difference in the number of teeth between the internal teeth 205 and the external teeth 204 is 1 is that a high reduction ratio can be achieved and the processing cost can be reduced compared to when the difference in the number of teeth is 2 or more.

Here, while the external teeth 204 mesh with the elliptical columnar internal teeth 205 in a state where the external gear 214 is inscribed in the internal gear 201, the phase of the maximum meshing portion (deepest meshing portion) of the 2 external gears 214 is shifted by 180 °.

Each of the external gears 214 has at least one, here 3 crank shaft holes 215 penetrating in the axial direction, and these crank shaft holes 215 are equally spaced apart from the central axis of the external gear 214 in the radial direction and equally spaced apart in the circumferential direction. Reference numeral 209 denotes a plurality of through holes (the same number as the number of crank shaft holes 215) formed in each external gear 214, and the through holes 209 are arranged alternately with the crank shaft holes 215 in the circumferential direction and are separated by equal distances in the circumferential direction.

The support 207 is a support (base) which is movably mounted in the rotary housing 202 and is attached to a fixed robot member (not shown), and the support 207 is composed of a pair of

end pillars

208 and 213 which are arranged on both outer sides in the axial direction of the external gear 214 and have a ring shape, and a plurality of (3 as many as the number of the through holes 209) columnar bodies 211 which are integrally connected to the end pillars 208 at one end and detachably connected to the end pillars 213 at the other end by a plurality of bolts 210. The cylindrical body 211 connecting the end posts 208 and 213 extends in the axial direction, and is inserted (loosely fitted) into the through hole 209 of the external gear 214 with a certain clearance.

Reference numeral 203 denotes a pair of bearings which are mounted between the outer peripheries of the support 207, specifically, the

end plates

208 and 213, and the inner peripheries of both ends of the rotating case 202 in the axial direction, and the support 207 rotatably supports the internal gear 201 via these bearings 203. The crankshafts 221 are at least one (3 as many as the number of the crank shaft holes 215) disposed at equal angular intervals in the circumferential direction, and these crankshafts 221 are rotatably supported by the supporting body 207, specifically, the end posts 208, 213, via tapered roller bearings 219 mounted on one end in the axial direction thereof and tapered roller bearings 219 mounted on the other end in the axial direction thereof.

The crank shaft 221 has 2 eccentric cam shafts 217 eccentric at equal distances from the central axis of the crank shaft 221 at the center in the axial direction, and the eccentric cam shafts 217 are shifted in phase by 180 ° from each other. Here, the eccentric cam shafts 217 of the crank shaft 221 are respectively fitted in the crank shaft holes 215 of the external gear 214, and needle roller bearings 218 are fitted therebetween; as a result, the external gear 214 and the crank shaft 221 are allowed to rotate relative to each other. Further, a fixed external gear 216 is attached to one end of each crank shaft 221 in the axial direction, and these external gears 216 mesh with an external gear 212 provided at one end of an output shaft 220 of a drive motor, not shown in the drawings.

When the eccentricity e is set to 0.225 times or more the tooth thickness S as described above, the outer teeth 204 whose tooth surfaces are in contact with the inner teeth 205 become thicker, that is, the tooth thickness and the tooth height are both increased, and therefore the outer teeth 204 go beyond the inner tooth root 201a of the inner gear 201 (the rotating case 202) located substantially on the inner tooth root circle p and enter, and interference occurs therebetween. Therefore, in embodiment 4, the external teeth 204 are cut off by a predetermined amount from the tooth tips along a circle having the center of curvature of the external gear 214 as the center (only the portion indicated by the broken line in fig. 11) to prevent the external teeth 204 from interfering with the internal tooth roots 201a of the internal gear 201. The amount of the external teeth 204 cut out is preferably such that a slight clearance is formed between the tips of the cut-out external teeth 204 and the internal tooth roots 201a of the internal gear 201 at the maximum meshing position between the internal gear 201 and the external gear 214.

The principle of partially cutting off each external tooth 204 as described above is: and cutting off each external tooth from the outer side to the inner side in the radial direction, wherein the cutting depth is determined by subtracting the root circle radius R of the internal tooth of the internal gear from the gear tooth top circle radius T of the external tooth and adding the eccentricity e of the external gear relative to the internal gear. The reason for this is that the outer teeth can be retained at the maximum, the bending rigidity of the outer teeth 204 can be ensured, and the outer teeth can be easily processed.

The operation of example 4 of the present invention will be described.

The driving motor operates, and the crank shaft 221 rotates in the same direction and at the same speed around its central axis. At this time, the eccentric cam shaft 217 of the crank shaft 221 eccentrically rotates in the crank shaft hole 215 of the external gear 214 to eccentrically oscillate the external gear 214, but the number of teeth of the external teeth 204 of the external gear 214 is smaller by 1 than the number of teeth of the internal teeth 205, and therefore the rotating case 202, the arm of the robot, and the like rotate at a low speed due to the eccentric oscillation of the external gear 214.

Here, since the eccentricity e is set to 0.225 times or more the tooth thickness S as described above, the distance Q from the center O of the internal gear 201 to the equivalent torque acting point C generated on the arm axis OL can be made larger than before, that is, the position of the equivalent torque acting point C generated on the arm axis OL can be moved greatly radially outward, and the acting line D is inclined to the tangential direction side larger than before with respect to the external gear 214, whereby the component force in the tangential direction of the driving component force K' increases, and the output torque increases.

Example 5

In embodiment 5, the external teeth 204 are not cut off as in embodiment 4, but the internal tooth roots 201a of the internal gear 201 (the rotating case 202) of all the internal teeth 205 are cut off to a predetermined depth: the internal teeth are cut from the inner side to the outer side in the radial direction, and the depth of the cut is at least more than the position determined by subtracting the radius R of the root circle of the internal teeth of the internal gear from the radius T of the gear crest circle of the external teeth and adding the eccentricity e of the external gear relative to the internal gear. This prevents the external teeth 204 from interfering with the internal tooth roots 201a of the internal gear 201 (the rotating case 202).

In embodiment 4 described above, a plurality of (3) crank shaft holes 215 are formed in the external gear 214, and the external gear 214 is eccentrically oscillated and rotated by inserting the crank shafts 221, which rotate at the same speed in the same direction, into the respective crank shaft holes 215, but in the present invention, one crank shaft may be inserted into 1 crank shaft hole formed in the central axis of the external gear 214, and the external gear may be eccentrically oscillated and rotated by the rotation of the crank shaft. In this case, the columnar body of the support must be in line contact with the inner periphery of the through hole.

In embodiment 4, the support 207 is fixed and the ring gear 201 is rotated at a low speed, but in the present invention, the ring gear may be fixed and the support may be rotated at a low speed. In the present invention, a spur gear reduction mechanism may be provided at a stage prior to the planetary gear reduction gear a iii to perform 2-stage reduction. Thus, the natural frequency of vibration can be increased and a high reduction ratio gear device can be obtained. In addition, while the external teeth 204 are cut off by a predetermined amount from the tooth tips in embodiment 4 described above, and the internal tooth roots 201a of the internal gear 201 (the rotating case 202) between the internal teeth 205 are cut off by a predetermined depth in embodiment 5, the external teeth and the internal tooth roots of the internal gear may be cut off at the same time in the present invention.

Comparison and analysis of technical innovation of the invention

1. In the devices described in patent documents 1 to 9, all of them adopt a cycloid pin gear structure, and in the conventional cycloid pin gear device bii structure cross-section principle shown in fig. 12, pin teeth 04 are generally adopted, that is, the cross section of internal teeth 04 (pin teeth) is circular, the pin teeth (internal teeth) 04 of an internal gear 03 are distributed on the inner periphery of the internal gear 03 with a radius Q at equal angles by the number Z of internal teeth 04, the number Z of pin teeth 04 is Z, the radius r (diameter d) of the pin teeth 04, and the offset of an external gear 06 with respect to the internal gear 03 is e. The reason why the output torque cannot be sufficiently transmitted by the internal tooth profile of the pin gear 04 is as follows: as shown in fig. 12, in the device, the external teeth 02 of the external gears 06 in contact with each other apply a driving force component in a direction perpendicular to the tooth surfaces to the internal teeth (rollers) 04 of the internal gear 03 at their contact points, and the internal teeth (rollers) 04 also apply a reaction force K of the driving force component to the external teeth 02 as a reaction internal teeth (rollers) 04. The lines of action D of the reaction forces K of the respective driving component forces are located on a line perpendicular to the tooth surface where the contact point is located, but since the internal teeth (rollers) 04 are cylindrical and the external teeth 02 are formed of trochoid tooth profiles as described above, the convergence points C, which are one point acting on the external gear 06, converge (intersect); the distance from the convergence point C to the center O of the internal gear is L. Then, a resultant force of the tangential direction component forces of the respective driving component forces acts on the internal gear 03 as a rotational driving force. However, since the reaction force K of each driving component force cannot increase the tangential driving component force of the internal gear, the tangential driving force is limited; therefore, when the external gear is engaged with the internal gear (pinwheel) in a transmission manner, under the condition of the same input driving force, a larger driving component force cannot be generated sufficiently, and because the component force in the tangential direction of the connecting line acting force from the engagement contact point to the circle center of the pintooth (internal tooth) cannot be increased, the output torque cannot be increased continuously, and the capacity of the transmission torque is limited.

2. The innovative elliptical tooth profile in the biii eccentric oscillating planetary gear reduction unit diagram of fig. 13 is preferred over the case of the cycloidal pin gear reduction unit bii for better comparison, illustration, and understanding. Parameters in the eccentric oscillating type planetary gear speed reducer diagram of bii: three parameters of the number Z of the teeth of the internal gear, the radius Q of the root circle of the internal gear and the offset e of the external gear relative to the internal gear are the same as those of the B II device of the cycloidal pin gear speed reducer, and columnar elliptic internal teeth (the tooth thickness is S (the tooth height is half of the tooth thickness S)) are used as the internal teeth of the internal gear in the B III device. In the structure of the B III eccentric swinging type planetary gear speed reducer, the tooth profile of the inner teeth of an inner gear 03 adopts elliptic columnar straight teeth 02, the inner teeth 02 of the inner gear are designed by adopting a new elliptic tooth profile, and the section of the inner teeth 02 is elliptic. The reason why the elliptical internal tooth profile can transmit the output torque more sufficiently is as follows: when the external gear is in driving engagement with the internal gear having the elliptical internal tooth profile, the driving component force can be further increased under the same condition as the input driving force, and the tangential component force of the normal force of the tooth surface of the elliptical internal tooth profile at the engagement contact point is increased as compared with that of the pin teeth, so that the output torque can be continuously increased, the transmission efficiency can be improved, and the output torque can be increased while preventing the increase in size.

The reason is as follows: as shown in fig. 13, the external teeth 02 of the external gears 06 in contact with each other in the device apply a driving force component in the direction perpendicular to the tooth surface to the elliptical internal teeth 04 of the internal gear 03 at their contact points, and the elliptical internal teeth 04 also apply a reaction force K of the driving force component to the external teeth 02 as a reaction force thereof. The lines of action D of the reaction forces K of the respective driving component forces described above are located on a line perpendicular to the tooth surface on which the above-described contact points are located, but these lines of action D act on the arm line OL of the external gear 06 and act equivalently as C' points because the external teeth 02 are formed of the special cycloid tooth profiles as described above by the elliptical internal tooth profiles; the distance from point C 'to the inner gear center O is L'. Then, a resultant force of the tangential direction component forces of the respective driving component forces acts on the internal gear 03 as a rotational driving force. However, comparing fig. 12 and 13, it can be seen that the OL' -arm is greater than OL, and at the same time, the tangential component force of each reaction force K in fig. 13 also increases; the following conclusions can be drawn by comparing the analyses of fig. 12 and 13: the elliptic internal tooth profile can output larger torque than the needle tooth profile, so that when the external gear is in transmission engagement with the elliptic internal tooth, under the condition of the same input driving force, the driving force component is larger than that of a cycloidal pin gear speed reducer.

3. For ease of understanding, an analytical force diagram of the effective working engagement region of the device is shown in FIG. 17.

In fig. 17, a conventional cycloid pin gear structure is shown to be constructed by: an internal gear M, a pin tooth A and the like; the radius of a distribution circle of the inner teeth of the inner gear is R, the radius of the pin teeth is R, the line H is the center of the pin teeth (or the elliptic teeth) and the center line of the inner gear, and the normal line F of the meshing point of the outer teeth D of the outer gear and the pin teeth of the inner gear is formed.

In fig. 17, the gear device of the present invention is composed of an internal gear M, elliptical internal teeth, and the like; the distribution circle radius of the inner teeth of the inner gear is R, the tooth height of the elliptic inner teeth is H, the tooth thickness is s (the tooth thickness s is approximately equal to 2 times of the radius R of the needle teeth), the H line passes through the center of the elliptic teeth (or the needle teeth) and the center line of the inner gear, and the normal line E of the meshing point of the outer teeth C of the outer gear and the needle teeth of the inner gear is formed.

When the planetary gear rotates clockwise, the internal gear (the pin gear) rotates clockwise, the external gear teeth D mesh with the internal gear teeth a, and a normal component force F of a force applied to the pin teeth a by the external gear teeth D passes through the center of the pin teeth in a speed direction V1 and forms a pressure angle β 1 with the speed direction, and the smaller the pressure angle, the higher the output efficiency, and the larger the output torque transmitted.

When the planetary gear rotates clockwise, the internal gear (elliptical internal gear) rotates clockwise, the external gear external teeth C mesh with the elliptical internal teeth B (in a small meshing region), and a normal component force E of a force applied to the elliptical internal teeth B by the external gear external teeth C is directed in a speed direction V2, the normal component force passes through the elliptical tooth flanks perpendicularly, and forms a pressure angle β 2 with the speed direction, and the smaller the pressure angle, the higher the output efficiency, and the larger the transmitted output torque.

Comparing the two pressure angles of beta 1 and beta 2 in the figure, the pressure angle of beta 2 is smaller than the pressure angle of beta 1; a small pressure angle indicates higher output efficiency and greater transmission torque; therefore, it is explained that the eccentric swinging type planetary gear speed reducer of the invention has the effects of improving the efficiency and increasing the output torque for the products of the devices.

Claims

1. An eccentric oscillating type planetary gear speed reducer capable of increasing output torque, comprising an internal gear, an external gear, a crank shaft and a support body, wherein the external gear is provided with at least one crank shaft hole and a plurality of through holes, the periphery of the external gear is provided with external teeth which are mutually meshed with internal teeth of the internal gear and have 1 less tooth number than the internal teeth; the crank shafts are inserted into the crank shaft holes, the external gear swings eccentrically by synchronously rotating the crank shafts, and the support bodies are cylindrical bodies inserted into the through holes and used for rotatably supporting the crank shafts; the external tooth is cycloid shape, its characterized in that: the internal gear is provided with internal teeth consisting of a plurality of elliptic cylindrical rollers at a certain pitch P on the inner periphery, the tooth height h of the elliptic cylindrical internal teeth is half of the tooth thickness S, the ratio of the tooth thickness S of the internal teeth divided by the certain pitch P of the internal teeth is reduced to the extent that the tooth tops of the external teeth exceed the tooth roots of the internal teeth in the radial direction, and the external teeth of the parts exceeding the tooth roots of the internal teeth are at least cut off, so that the interference between the external teeth and the tooth roots of the cylindrical elliptic internal teeth is avoided;

when the external teeth are cut along a line V connecting inflection points 04d and 04e of both tooth surfaces, a distance A between the inflection points 04d and 04e is larger than a position determined by subtracting a root circle radius R of the internal gear from a tooth crest circle radius T of the external teeth and adding an eccentric amount e of the external gear to the internal gear.

2. An eccentrically oscillating planetary gear speed reducer with increased output torque as set forth in claim 1, wherein: the ratio of the thickness S of the inner teeth to the pitch P of the inner teeth is reduced to a value that the tooth tops of the outer teeth exceed the tooth roots of the inner teeth in the radial direction, at least the tooth roots of the inner teeth between adjacent inner teeth are cut off, and the depth of the part of the outer tooth tops exceeding the inner tooth roots of the inner teeth is measured, so that the interference between the outer teeth and the cylindrical elliptic inner tooth roots is avoided.

3. An eccentric oscillating type planetary gear speed reducer capable of increasing an output torque according to claim 1 or 2, wherein: when the radius of the root circle of all columnar elliptic internal teeth constituting the internal teeth is R, and the line D of action of the reaction force K applied to the corresponding internal teeth from the normal direction of the tooth profile surface of the internal gear to the external teeth is made to intersect with the equivalent moment action point C generated on the arm axis OL, and the distance OC of the point C in the radial direction is Q, the distance Q of the point C in the radial direction is in the range of 0.85 to 1.00 times of the radius R of the root circle.