JP2563266Y2 - Eccentric differential reducer - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eccentric differential type speed reducer used as a drive mechanism of a robot.

[0002]

2. Description of the Related Art In many cases, a reduction gear is used as a part of a driving mechanism of an industrial robot provided in an automated manufacturing line or the like. One of them is an eccentric differential reduction gear.
Such an eccentric differential type speed reducer is provided with (a) an annular member provided with a large number of inner peripheral teeth around one center line, and (b) a rotatable relative to the annular member around the one center line. And a holding member for holding a plurality of crankshafts rotatably around their respective axes at positions eccentric from one center line thereof; and (c) the inner peripheral teeth and the number of teeth of the annular member are The plurality of crankshafts having different outer teeth are eccentrically disposed inside the annular member and are engaged with the plurality of crankshafts. An eccentric rotating member that is eccentrically rotated about the one center line in a state where a part of the teeth mesh with the inner peripheral teeth, and one of the annular member and the holding member is fixed so as not to rotate about the one center line. To be done Thus, the rotation input to the crankshaft is decelerated to take out the output from the other of the annular member and the holding member. Recently, the resonance point has been used frequently because of its advantages such as high resonance point and excellent rigidity. I have.

FIG. 7 is a cross-sectional view showing an example of such an eccentric differential type speed reducer, and FIG. 8 is a structural conceptual diagram thereof. The annular member 100 has a large number of pins 102 as inner peripheral teeth, and a pair of eccentric gears (eccentric rotating members) 106 and 108 having trochoid outer teeth 104 having one less number of teeth than the number of pins 102 are provided. It is disposed eccentrically inward, and its outer peripheral teeth 104 are partially engaged with the pin 102. A holding member 110 composed of two members sandwiching the eccentric gears 106 and 108 from both sides is disposed so as to be rotatable around a center line with respect to the annular member 100 via a bearing 112. The holding member 110
The crankshaft 116 rotatably disposed via a bearing 114 is disposed at equal angular intervals at three locations in the circumferential direction as shown in FIG. 9 which is a left side view partially omitted. A spur gear 118 having the same number of teeth is provided at the end.
Are fixed respectively. Each of the spur gears 118 is meshed with a central input gear 120, and a crankshaft 116 to which each spur gear 118 is fixed is attached.
Of the eccentric shaft portions 122 and 124 are synchronized with each other. An output shaft such as a servomotor is connected to the input gear 120. When the input gear 120 is driven to rotate, three crankshafts 1 are driven.
The eccentric gears 106, 108 engaged with the eccentric shaft portions 122, 124 of the crankshaft 116 via bearings 126 respectively have their outer peripheral teeth 104 partially part of the annular member 100. It is eccentrically rotated about the one center line while engaging with the pin 102. The pair of eccentric shaft portions 122 and 124 are symmetrically eccentric with respect to the axis of the crankshaft 116, and the pair of eccentric gears 106 and 108 are eccentric to opposite sides to be engaged with the annular member 100. It has become so.

[0004] For example, one eccentric gear 108 is
In the state of FIG. 7, the outer teeth 104 are engaged with the pin 102 of the annular member 100 at the lower part of the figure, but the input gear 120 is driven to rotate counterclockwise in FIG. 9 and the spur gear 118 is rotated substantially half clockwise. Until the state shown in FIG. 10, the eccentric gear 108 rotates eccentrically while engaging with the left half pin 102 in FIG. 10, and comes to a position where it engages with the pin 102 in the upper part of the figure. At this time, since the number of the inner peripheral teeth 104 is one less than the number of the pins 102, the holding member 110 that holds the eccentric gear 108 via the eccentric gear 108 and the crankshaft 116 The ring member 100 is rotated relative to the annular member 100 by an angle corresponding to a half pitch. When the input gear 120 is further rotated counterclockwise and the spur gear 118 is further rotated half a turn, the eccentric gear 108 rotates eccentrically while engaging with the right half pin 102 as shown in FIG. The eccentric gear 1 is engaged with the pin 102.
08 and the holding member 110 have been rotated counterclockwise relative to the annular member 100 by an angle of one pitch of the pin 102. Thus, the spur gear 1
The eccentric gears 106 and 108 and the holding member 110 are rotated by an angle of one pitch every one rotation of the ring member 10.
0 and the holding member 11
If one of the ring member 100 and the annular member 100 is fixed so as not to rotate, the rotation of the spur gear 118 can be taken out from the other member at a reduced speed. The first-stage speed reduction is performed according to the ratio of the number of teeth between the input gear 120 and the spur gear 118.

[0005]

However, when such an eccentric differential type speed reducer is to be disposed at the base end of an arm of a robot or the like, a mechanism such as a wrist shaft at the end of the arm is driven. It is difficult to arrange a drive shaft, cables, and the like through the inside of the drive shaft and cables. Specifically, in order to secure a space near the center of the eccentric differential reduction gear of FIG. 7, for example, as shown in FIG.
In addition to the eccentricity of the connection position of the drive source input shaft 132 with respect to the
34, the input gear 130
Therefore, it is difficult to secure a sufficient space through which the drive shaft and the cable can pass. In addition, the bearing 136 for supporting the input gear 130 itself, etc. There is a disadvantage that the bearing structure is required and the structure becomes complicated.

Further, the first-stage speed reduction is performed according to the gear ratio between the input gear (input rotary member) and the spur gear (intermediate rotary member). The input gear is disposed at the center of the plurality of spur gears. Because the gears are directly meshed with each other, the degree of freedom in setting the reduction ratio is limited by the interrelation between the shafts, etc., and when changing the reduction ratio, all gears must be changed. was there.

The present invention has been made in view of the above circumstances, and has as its object the purpose of being able to arrange a drive shaft, a cable or the like through the center portion and to have a high degree of freedom in setting the reduction ratio. An eccentric differential type reduction gear is provided.

[0008]

In order to achieve the above object, the present invention comprises the above-mentioned (a) annular member, (b) holding member, and (c) eccentric rotating member, wherein the annular member is provided. And one of the holding members is fixed so as not to rotate about the one center line, so that the rotation input to the crankshaft is reduced and the eccentric differential type reduction speed output from the other of the annular member and the holding member is output. (D)
A plurality of intermediate rotating members each having the same number of teeth fixed to the plurality of crankshafts; (e) an annular power transmission member meshed with each of the plurality of intermediate rotating members such that they cannot rotate relative to each other; An input rotating member disposed at a position eccentric from the one center line and engaged with any one of the plurality of intermediate rotating members and the power transmission member to rotate and drive; (g) the holding member on the one center line And an insertion hole penetrating the eccentric rotation member.

[0009]

In the above-described eccentric differential type speed reducer, any one of the plurality of intermediate rotating members and the annular power transmitting member meshed with each of the plurality of intermediate rotating members such that they cannot rotate relative to each other is provided. The plurality of intermediate rotating members having the same number of teeth are rotated while being meshed with the power transmission member by being rotationally driven by an input rotating member disposed at a position eccentric from one center line, so that a plurality of crankshafts are synchronized. And the eccentric rotation member is eccentrically rotated. Thereby, the holding member holding the eccentric rotating member and the annular member are relatively rotated via the crankshaft at a predetermined reduction ratio, and one of them is fixed so as not to rotate, so that the deceleration output is obtained from the other. Can be taken out.

Here, the eccentric differential type speed reducer of the present invention is:
Since the plurality of crankshafts and the input rotary member are disposed at positions eccentric from one center line, an insertion hole can be provided through the eccentric rotary member and the holding member on one center line, and the insertion hole can be provided. A drive shaft such as a robot arm, a cable, and the like can be provided through the hole.

Further, the intermediate rotating member and the input rotating member to which the rotation is transmitted via the power transmitting member can have a relatively free number of teeth without being restricted by the mutual relationship such as the distance between the shafts as in the prior art. In addition, since it can be changed in a wide range, the setting range of the first-stage reduction ratio is expanded by them, and the reduction ratio can be changed relatively easily, for example, the reduction ratio can be changed only by changing the number of teeth of the input rotary member. Become.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a view showing an eccentric differential type speed reducer (hereinafter simply referred to as a speed reducer) 10 according to an embodiment of the present invention, and a base end portion of a robot arm using the speed reducer 10. It is sectional drawing in parallel with one center line L in the vicinity. FIG. 2 is a sectional view taken along the line IIa-IIa in FIG.
-IIb is a composite cross-sectional view showing a cross section half by the left and right sides of the paper. In this speed reducer 10, a holding member 14 is integrally attached to a base member 12 at a base end of a robot arm, and an annular member 18 is integrally connected to an arm member 16, so that an input from a drive source is provided. The arm member 16 is configured to be driven to rotate about one center line L by reducing the rotation that has been performed and outputting the rotation from the annular member 18. Although not shown, an operating shaft such as a wrist shaft is provided on the distal end side of the robot arm.

On the inner peripheral surface of the cylindrical annular member 18 centered on one center line L, a large number (40 in this embodiment) of pins 20 as inner peripheral teeth constituting a pin gear are provided. They are provided integrally at a constant pitch in parallel with L. Inside the annular member 18, a pair of eccentric gears 22 and 24 having a disk shape are eccentrically arranged in a posture perpendicular to one center line L.
The outer teeth 26 of the trochoid tooth shape capable of meshing with the pin 2
It is provided at a constant pitch by one less than 0. The eccentric gears 22 and 24 correspond to eccentric rotating members, and can be eccentrically rotated in the annular member 18 in a state where the outer teeth 26 and the pins 20 partially mesh with each other. Each of the eccentric gears 22 and 24 has three relief holes 28 at regular intervals in the circumferential direction.
The holding member 14 includes a first member 14a and a second member 14b which penetrate the three relief holes 28 and are located on both sides thereof and integrally connected by pins 29 and bolts 31. The first member 14a is fixed to the base member 12 by pins 33 and bolts 35. The annular member 18 is supported by the first member 14a and the second member 14b via a pair of bearings 30 so as to be rotatable around one center line L. Note that a seal member 32 is interposed in a gap portion on the outer peripheral side of the holding member 14 and the annular member 18.

As shown in FIG. 2, the holding member 14 has
Three crankshafts 34 are arranged at equal intervals on one circumference centered on one center line L, each of which is a first member 14 a of the holding member 14 via a pair of bearings 36.
And a second member 14b rotatably supported about an axis. A spur gear 38 is fixed to an end of the base member 12 on the base member 12 side by spline shaft fitting or the like so as to be relatively non-rotatable. These three spur gears 38 correspond to an intermediate rotating member, and have the same number of teeth and various dimensions. The pair of eccentric shaft portions 40 and 42 of each crankshaft 34 are respectively provided with the pair of eccentric gears 22 and 24 and the bearing 4 at the intermediate position in the circumferential direction of the three relief holes 28.
4 so as to be rotatably engaged with each other. By this engagement, the pair of eccentric gears 22 and 24 are moved to the eccentric shaft portion 4.
It is designed to be eccentric with respect to one center line L by an eccentric amount of 0, 42. The left eccentric gear 22 in FIG.
Is engaged with the pin 20 at the upper part of the annular member 18, while the right eccentric gear 24 is engaged with the pin 20 at the lower part of the annular member 18. That is, the eccentric phases of the eccentric shaft portions 40 and 42 are shifted by 180 °. The three spar gears 38 and the ring gear 48 are previously set so that the mutual phases of the eccentric shaft portions 40 and 42 between the crankshafts 34 are synchronized at all three positions in the assembled state.
The initial angle and the like at the time of meshing with are defined.

The first member 14a of the holding member 14 also has
A ring gear 48 is rotatably disposed around one center line L outside the three spur gears 38 via a bearing 46, and each spur gear 38 meshes with an inner peripheral tooth 50 of the ring gear 48. on the other hand,
At a position eccentric from one center line L, the input gear 52
Servomotor 54 provided at the end of the output shaft
2 and the input gear 52
Also mesh with the inner peripheral teeth 50 of the ring gear 48. Therefore, when the servomotor 54 is driven to rotate the input gear 52 clockwise as viewed from the left side of FIG. 1, the ring gear 48 is driven clockwise in FIG. 2 is rotated clockwise in a pair of eccentric gears 2.
2, 24 are also eccentrically rotated clockwise. At this time, since the rotation centers of the holding member 14 and the three crankshafts 34 are fixed in position, a part of the outer peripheral teeth 26 of the pair of eccentric gears 22 and 24 and the pins 20 of the annular member 18 mesh with each other. Each time the eccentric gears 22 and 24 make one rotation, the annular member 18 is rotated clockwise in FIG. 2 by an angle (1/40 rotation in this embodiment) corresponding to the pitch of the pins 20.

FIG. 3 shows a structural conceptual diagram of the speed reducer 10 configured as described above. In this embodiment, the ring gear 48 corresponds to a power transmitting member, and the input gear 52 corresponds to an input rotating member. Also, spur gear 3
8, the ring gear 48, the input gear 52, etc.
While the reduction part 90 is comprised, the holding member 14,
The second reduction portion 92 is constituted by the annular member 18, the eccentric gears 22, 24, the crankshaft 34, and the like. Assuming that the number of teeth of the input gear 52 at this time is Z _{1, the} number of teeth of _the spur gear 38 is Z ₂ , and the number of pins 20 is Z ₃ , the reduction ratio (the number of rotations of the annular member 18 / the number of rotations of the input gear 52) i Is represented by the following equation (1).

[0018]

I = Z ₁ / (Z ₂ · Z ₃ ) (1)

By the way, the holding member 14 and the pair of eccentric gears 22 and 24 are provided with through holes 56 and 58 at a central portion near one center line L, respectively. , The first drive shaft 60,
The second drive shaft 62 and the cable 64 are respectively inserted therethrough. The first drive shaft 60 and the second drive shaft 62 are supported by the base member 12 via bearings 66 and 68 so as to be concentric with one center line L and rotatable about the axis. The right side of 16 (not shown) is connected to an operating shaft such as a wrist shaft. Gears 70 and 72 are integrally fixed to the first drive shaft 60 and the second drive shaft 62 at the ends on the base member 12 side, respectively. A second servomotor 74 and a third servomotor 76 for driving shafts and the like are fixedly provided, respectively, and output shaft gears 78 and 80 (see FIG. 4) of the servomotors 74 and 76 and the gears 70 and 72. Are driven in mesh with each other, so that rotation is transmitted to the operating shaft via the first drive shaft 60 and the second drive shaft 62. The cable 64 makes an electrical connection with the distal end of the arm member 16. FIG. 4 is a left side view of FIG. 1 and shows a state where the servomotor 54, the second servomotor 74, and the third servomotor 76 are eccentrically arranged around one center line L.

As described above, in this embodiment, the ring gear 48 meshing with the spur gear 38 is provided, and the input gear 52 for driving the ring gear 48 is provided.
Is disposed at a position eccentric from one center line L, so that the holding member 14
And a first drive shaft 60 and a second drive shaft 62 for forming the insertion holes 56 and 58 in the eccentric gears 22 and 24 and driving the operating shaft at the tip end side of the arm member 16 through the insertion holes 56 and 58; A cable 64 can be provided. Thus, the robot arm using the speed reducer 10 can be simply and compactly configured without disposing the drive shaft and the like outside the arm member 16.

Further, the input gear 52 and the spur gear 38 to which the rotation is transmitted via the ring gear 48 are compared with the number of teeth Z ₁ and Z ₂ without being restricted by the mutual relation such as the distance between the shafts as in the prior art. Since the range can be changed freely and in a wide range, the range in which the first reduction unit 90 can set the reduction ratio based thereon is expanded, and the reduction ratio can be easily changed.

FIG. 5 is a view showing another embodiment of the present invention, in which the ring gear 48 in the embodiment of FIG. 1 described above is replaced with a timing belt 82, and the spur gear 38 and the input gear 52 are replaced with a timing pulley 84.
And 86 respectively. Also in this case, when the timing pulley 86 is rotationally driven by a servo motor (not shown) or the like which is arranged concentrically with the timing pulley 86, the timing pulley 86 meshes with the timing belt 82 so as to be relatively non-rotatable. The two timing pulleys 84 are synchronously rotated. In addition, a backup pulley may be provided outside the timing belt 82 at the position of the timing pulley 86 as needed. In the vicinity of one center line L, a space is provided for the first drive shaft 60, the second drive shaft 62, and the cable 64, respectively. The timing belt 82 corresponds to a power transmission member, the timing pulley 84 corresponds to an intermediate rotating member, and the timing pulley 86 corresponds to an input rotating member.

Also in this embodiment, as in the embodiment of FIG. 1, a sufficient hollow space can be secured near one center line L, and the degree of freedom in setting the reduction ratio is improved. Further, since the timing belt 82 has a small inertia and a small backlash as compared with the ring gear 48, the rotation accuracy can be improved. Further, since the timing belt 82 is made of an elastic material such as rubber, the operation is smoothed by absorbing the inertia at the time of starting and stopping the drive, and the speed reducer is damaged by absorbing the impact load from the output side. The effect of preventing is obtained.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be implemented in other modes.

For example, in the embodiment of FIG. 1 described above, the case where the holding member 14 is fixed and the speed is reduced and output from the annular member 18 has been described. However, as shown in the structural conceptual diagram of FIG. 18 is non-rotatably fixed to the base member 12, the holding member 14 is connected to the arm member 16, and the eccentric gears 22 and 24 are rotated with the eccentric rotation. It is also possible to drive 16.

Also, as in the above-described embodiment, the holding member 14
Is fixed, and the annular member 18 is rotated at a reduced speed, the plurality of crankshafts 34 do not necessarily have to be disposed on one circumference centered on one center line L, and are eccentric from the one center line L. The input gear 52 and the timing pulley 86 may be provided at arbitrary positions.
Alternatively, it is possible to engage with any one of the timing pulleys 84.

In the above embodiment, the holding member 14 holds the three crankshafts 34 and the three spur gears 38 are provided. However, the number of the crankshafts 34 is two. Eccentric gear 2
The number of the crankshaft 34 and the number of the spur gears 38 may be two or four or more because the two and 24 can be eccentrically rotated.

In the embodiment of FIG. 1 described above,
The tooth profile of the ring gear 48, the spur gear 38, and the input gear 52 that mesh with each other has not been particularly described. And other engagement elements with the same may also be used.

In the above-described embodiment, a large number of pins 20 are provided on the annular member 18 as inner peripheral teeth, and a large number of trochoid outer teeth 26 are provided on the eccentric gears 22 and 24.
However, instead of these, the inner peripheral teeth and the outer peripheral teeth of other tooth shapes such as an involute tooth shape and a cycloid tooth shape that can mesh with each other in a general internal gear may be provided.

Further, in the above-described embodiment, the pair of eccentric gears 22 and 24 have the outer teeth 26 which is one less than the number of the pins 20, but the number of the outer teeth 26 is It is possible to construct an eccentric differential reduction gear even if the number is smaller by two or more than.

In the embodiment of FIG. 5 described above,
The timing belt 82 is used as a power transmission member,
Although the timing pulleys 84 and 86 meshing with the timing belt 82 are used as the intermediate rotating member and the input rotating member, a chain and a sprocket may be used instead of the timing belt 82 and the timing pulleys 84 and 86. good.

In the above-described embodiment, the insertion hole 5
A first drive shaft 60, a second drive shaft 62, and a cable 64 for driving the working shaft into 6 and 58
However, it is also possible to dispose a pneumatic hydraulic pipe, a hose for coolant or vacuum, and a supply duct such as a parts feeder.

In the above-described embodiment, the speed reducer 1
Although 0 is provided at the base end of the robot arm, it can be similarly provided at a joint or the like of a multi-axis joint robot.

Although not specifically exemplified, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of the drawings]

FIG. 1 is a sectional view parallel to a center line L showing an embodiment of an eccentric differential type reduction gear of the present invention.

2 is a diagram showing a cross section taken along a line IIa-IIa and a cross section taken along a line IIb-IIb in FIG. 1;

FIG. 3 is a conceptual diagram of the structure of the eccentric differential type speed reducer shown in FIG.

FIG. 4 is a left side view of the embodiment of FIG. 1;

FIG. 5 is a diagram showing a main part of another embodiment of the present invention.

FIG. 6 is a structural conceptual view for explaining still another embodiment of the present invention.

FIG. 7 is a cross-sectional view showing an example of a conventional eccentric differential reduction gear.

FIG. 8 is a structural conceptual diagram of the conventional example of FIG. 7;

FIG. 9 is a left side view in which a part of the conventional example of FIG. 7 is omitted.

FIG. 10 is a sectional view of a main part for explaining the operation of the conventional example of FIG. 7;

11 is a cross-sectional view of a main part for describing the operation of the conventional example of FIG.

FIG. 12 is a sectional view of a main part for describing a problem in a conventional eccentric differential type reduction gear.

[Explanation of symbols]

 10: Eccentric differential type reduction gear 14: Holding member 18: Annular member 20: Pin (inner peripheral teeth) 22, 24: Eccentric gear (eccentric rotating member) 26: Outer peripheral teeth 34: Crank shaft 38: Spur gear (intermediate rotating member) 48: Ring gear (power transmission member) 52: Input gear (input rotary member) 56, 58: Insertion hole 82: Timing belt (power transmission member) 84: Timing pulley (intermediate rotary member) 86: Timing pulley (input rotary member) )

Claims (1)

(57) [Scope of request for utility model registration] 1. An annular member having a plurality of inner peripheral teeth provided around one center line, and is disposed so as to be rotatable relative to the annular member around the one center line. A holding member that holds a plurality of crankshafts rotatably around their respective axes at eccentric positions; and an outer peripheral tooth having a different number of teeth from the inner peripheral teeth of the annular member. It is arranged eccentrically and is engaged with the plurality of crankshafts, and the plurality of crankshafts are rotationally driven in synchronization with each other, so that a part of the outer peripheral teeth mesh with the inner peripheral teeth. An eccentric rotation member that is eccentrically rotated about the one center line, and one of the annular member and the holding member is fixed so as not to rotate about the one center line, so that the rotation input to the crankshaft is provided. Slow down An eccentric differential type reduction gear output from the other of the annular member and the holding member, wherein: a plurality of intermediate rotating members fixed to the plurality of crankshafts and having the same number of teeth; An annular power transmission member meshed with each other so as to be relatively non-rotatable; and an input arranged at a position eccentric from the one center line and meshed with any of the plurality of intermediate rotation members and the power transmission member to rotate and drive. An eccentric differential type reduction gear comprising: a rotating member; and an insertion hole provided through the holding member and the eccentric rotating member on the one center line.