JP2006329434A - Speed reducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a speed reducer in which the inside diameter of a hollow camshaft can be increased without increasing the size. <P>SOLUTION: An output pin 9 can be maintained in rigidity even by narrowing the diameter because both the ends are supported by bearings 10, 11, 15 and 16. Thereby, since a free space can be obtained around the hollow camshaft 1, the diameter of the hollow camshaft 1 can be increased without increasing the size of the speed reduction gear. Since two toothed discs 5 and 6 are provided, when three, for example, toothed discs are provided, a sleeve which is necessary to be fitted into the hollow camshaft 1 can be eliminated. Thereby, without increasing the size of the speed reduction gear, the inside diameter of the hollow camshaft 1 can be increased. In addition, since needle bearings 3 and 4 to rotatably and alternately support the hollow camshaft 1 and the toothed discs 5 and 6 are lower in the radial height than that of a ball bearing, for example, the inside diameter of the hollow camshaft 1 can be increased without increasing the size of the speed reduction gear. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a reduction gear, and more particularly to a reduction gear with a large reduction ratio used for driving a robot or the like.

  In an industrial robot, for example, in order to operate a cantilever arm, a high torque power source is required. On the other hand, motors or the like that are normally used as a power source have output characteristics of high rotation and low torque, so it is inappropriate to use the rotational force as it is to drive the robot. It is necessary to let Therefore, a speed reducer is interposed in the power transmission path between the motor and the robot.

  For example, a multi-stage gear reducer is well known as a reducer, but in order to obtain a high reduction ratio, it is necessary to combine many stages of gear pairs, which makes the whole structure large and heavy. There is a problem of increasing.

  Therefore, a reduction gear that can transmit power with a large reduction ratio using a toothed disk that moves eccentrically has been developed. According to such a reduction gear, it is possible to convert power from a motor or the like into an output of low rotation and high torque while being lightweight and compact.

  By the way, in a reduction gear for a robot, there is a design philosophy to make effective use of space by hollowing a cam shaft for driving an eccentric disk and passing a wiring for controlling a robot or the like inside the cam shaft.

  Based on this design concept, the larger the inner diameter of the hollow cam shaft, the better. However, since the size of the entire speed reducer is limited, in order to increase the inner diameter of the hollow camshaft, it is necessary to carefully consider the shape and arrangement of components provided inside the speed reducer.

  An object of the present invention is to provide a speed reducer that can increase the inner diameter of a hollow camshaft without increasing the size of the speed reducer.

  In order to achieve the above object, a speed reducer according to the present invention includes a housing, an eccentric cylindrical portion, a hollow cam shaft that is rotatably supported by the housing, and an eccentric cylinder according to the rotation of the hollow cam shaft. A toothed disk revolving around the axis of the hollow cam shaft, an internal tooth body having internal teeth meshing with external teeth provided in the toothed disk, and the hollow from the housing A plurality of pin portions extending around a cam shaft and supporting the toothed disk so as to be capable of revolving, the pin portions being supported by housings at both ends, the toothed disk being Two hollow camshafts and the toothed disk are rotatably supported by a needle bearing.

  According to the speed reducer of the present invention, since both ends of the pin portion are supported by the housing, rigidity can be maintained even if the diameter is reduced, thereby ensuring a free space around the hollow camshaft. Therefore, the diameter of the hollow camshaft can be increased without increasing the size of the reduction gear. Furthermore, since two toothed disks are provided, for example, when three toothed disks are provided, a sleeve that needs to be fitted to the hollow camshaft can be eliminated, thereby reducing the size of the speed reducer. It is possible to increase the inner diameter of the hollow cam shaft without increasing. In addition, the needle bearing that rotatably supports the hollow camshaft and the toothed disk is lower in the radial direction than, for example, a ball bearing, thereby increasing the size of the speed reducer. It is possible to increase the inner diameter of the hollow camshaft.

  Hereinafter, a first embodiment according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view in the axial direction of a speed reducer for driving a robot, for example. In FIG. 1, the reduction gear has a hollow camshaft 1 disposed at the center. A male spline portion 1a is formed on the outer periphery of the left end of the hollow camshaft 1 in the figure, and a gear 2 having a female spline portion 2a facing the male spline portion 1a is engaged with both spline portions 1a and 2a. It is attached to the hollow camshaft 1 so as to be combined. The power from the drive source is transmitted to the hollow camshaft 1 via the gear 2.

  Two eccentric portions 1b and 1c, which are cylindrical portions eccentric to the axis of the hollow cam shaft 1, are formed on the outer periphery of the center of the hollow cam shaft 1. The eccentric phases of the eccentric portions 1b and 1c are shifted from each other by 180 degrees. Needle bearings 3 and 4 are arranged around the eccentric portions 1b and 1c. The needle bearings 3, 4 support the toothed disks 5, 6 arranged radially outwardly so as to be rotatable with respect to the hollow cam shaft 1. The needle bearing means a bearing using a cylindrical or conical roller or roller as a rolling element. In this embodiment, a cylindrical roller is used.

  FIG. 2 is a view of the speed reducer in FIG. 1 taken along line II-II and viewed in the direction of the arrow. Since the toothed disks 5 and 6 described below have the same shape, only the toothed disk 6 shown in FIG. 2 will be described in detail. As apparent from FIG. 2, the toothed disk 6 has a large opening 6 a in the center, and the large opening 6 a is provided in the needle bearing 4 with respect to the eccentric portion 1 c of the hollow camshaft 1. It is supported via a large number of rollers 4a.

  Further, the toothed disk 6 has 13 peripheral openings 6b formed at equal intervals around the large opening 6a, and a wavy external tooth 6c composed of a pericycloidal curve is formed on the outer periphery thereof. ing. On the other hand, a tubular output portion 7 is arranged on the outer side in the radial direction of the toothed disk 6. The output part 7 is opposed to the external teeth 6 c of the toothed disk 6, and pins 7 a are embedded at equal intervals on the inner periphery thereof. As is apparent from FIG. 2, the number of external teeth 6a is one less than the number of pins 7a. The relationship between the toothed disk 5 and the output unit 7 is the same, but the eccentric phases of the toothed disks 5 and 6 are shifted by 180 degrees as described above.

  In the right side of FIG. 1, a housing 8 disposed around the hollow cam shaft 1 and inside the output portion 7 rotatably supports the hollow cam shaft 1 via a tapered roller bearing 10, while the tapered roller bearing is provided. The output unit 7 is rotatably supported via 11.

  The housing 8 is formed with 13 holes 8a (FIG. 2), and the output pins 9 are fitted into the holes 8a. A roller 12 is rotatably fitted on the outer periphery of the center portion of the output pin 9. A female screw 9a is formed at the left end of the output pin 9 in FIG.

  A ring portion 14 is disposed around the left end of the hollow cam shaft 1 in FIG. 1 and inside the output portion 7. The ring portion 14 has thirteen through holes 14a arranged at equal intervals in the circumferential direction. The ring portion 14 is fitted to the output pin 9 by fitting the bolt 13 inserted through the through hole 14a into the female screw 9 of the output pin. Therefore, the output pin 9 and the ring portion 14 become a part of the housing 8 and form a strong rigid support structure. The ring portion 14 rotatably supports the hollow camshaft 1 via a tapered roller bearing 15, while the output portion 7 is rotatably supported via a tapered roller bearing 16.

  Next, the operation of the speed reducer according to the present embodiment will be described below with reference to FIGS. First, the rotational force transmitted from a power source (not shown) is transmitted to the hollow camshaft 1 through the gear 2 and rotates the hollow camshaft 1 at a predetermined rotational speed. When the hollow cam shaft 1 rotates, the eccentric portions 1 b and 1 c revolve around the axis of the intermediate shaft 8. By this revolving motion, the two toothed discs 5 and 6 are pushed through the needle bearings 3 and 4, whereby the toothed discs 5 and 6 also revolve with respect to the axis of the hollow camshaft 1. Become.

  At this time, the external teeth 6c of the toothed discs 5 and 6 perform an operation of getting over the pin 7a, but the output unit 7 is pushed and rotated by one pitch of the pin 7a. The external teeth 6c get over the single pin 7a when the eccentric portions 1b and 1c revolve one revolution, and the reduction ratio becomes (the number of 1 / pins 7a). In the present embodiment, 1 : A high reduction ratio of 40 is obtained.

  By the way, in the present embodiment, when the toothed disks 5 and 6 are revolved, the output pin 9 which receives a force by contacting the inner periphery of the peripheral opening 6b is provided at both ends (the housing 8 and the ring portion 14). ) Is supported by tapered roller bearings 10, 11, 15, and 16. Accordingly, the outer diameter can be reduced even if the same rigidity (deflection amount) is ensured as compared with the output pin of the prior art which is cantilevered. Therefore, it is possible to increase the outer diameter and inner diameter of the hollow camshaft 1 by reducing the outer diameter of the output pin 9 without increasing the size of the reduction gear. If the inner diameter of the hollow camshaft 1 is increased, for example, a robot control cable can be easily passed through the hollow camshaft 1 and the degree of freedom in robot design is improved.

  Furthermore, according to the present embodiment, two toothed disks 5 and 6 are provided. For example, as a reduction gear according to the prior art, one having three toothed disks has been developed (see JP-A-1-169154). However, in such a speed reducer, since the toothed disk needs to be shifted in phase by 120 degrees, at least one of the eccentric parts for driving the three toothed disks is formed on the sleeve for the convenience of manufacturing. Therefore, such a sleeve must be fitted to the outer periphery of the hollow camshaft. In the configuration in which the sleeve is fitted to the hollow cam shaft as described above, the thickness of the hollow cam shaft must be increased, and as a result, the inner diameter is decreased. On the other hand, in the present embodiment, since the two toothed disks 5 and 6 are provided, the sleeve necessary in the prior art can be eliminated, thereby increasing the size of the speed reducer. The inner diameter of the hollow camshaft 1 can be increased without this.

  In addition, since the outer diameter of the toothed disks 5 and 6 is limited by the size of the speed reducer, if the diameter of the output pin 9 is determined, the inner diameter of the large opening 6a of the toothed disks 5 and 6 is determined. End up. Therefore, it can be said that there is a great limitation in increasing the diameter of the large opening 6a. On the other hand, according to the present embodiment, the needle bearings 3 and 4 that support the hollow camshaft 1 and the toothed disks 5 and 6 so as to be rotatable with respect to each other are higher in the radial direction than, for example, a ball bearing. Therefore, the outer diameter and the inner diameter of the hollow camshaft 1 can be increased by the difference in height without changing the inner diameter of the toothed disks 5 and 6. If the inner diameter of the hollow camshaft 1 is increased, for example, a robot control cable can be easily passed through the hollow camshaft 1 and the degree of freedom in robot design is improved.

  The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be appropriately changed / improved. For example, the speed reducer of the present invention can be used for industrial machines other than robots (such as winches). In this embodiment, the housing 8 is fixed and the output is taken out from the output unit 7. However, the output unit 7 can be fixed and the output can be taken out from the housing 8. is there.

  According to the speed reducer of the present invention, since both ends of the pin portion are supported by the bearings, the rigidity can be maintained even if the diameter is reduced, so that an empty space can be secured around the hollow camshaft. Therefore, it is possible to increase the diameter of the hollow cam shaft without increasing the size of the reduction gear. Further, since two toothed disks are provided, for example, when three toothed disks are provided, a sleeve that needs to be fitted to the hollow camshaft can be eliminated, thereby reducing the size of the reduction gear. It is possible to increase the inner diameter of the hollow cam shaft without increasing it. In addition, the needle bearing that rotatably supports the hollow camshaft and the toothed disk is lower in radial direction than, for example, a ball bearing, so that without increasing the size of the speed reducer, It becomes possible to increase the inner diameter of the hollow camshaft. Further, if an input gear having a smaller number of teeth than that of the gear 2 is attached to the motor and the gear 2 and the input gear are engaged with each other, there is an effect of shifting the resonance point.

It is sectional drawing of the axial direction of the reduction gear concerning this Embodiment. It is the figure which cut | disconnected the reduction gear of FIG. 1 by the II-II line | wire, and looked at the arrow direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hollow cam shaft 2 Gear 3, 4 Needle bearing 5, 6 Toothed disk 6a Large opening 6b Small opening 6c External tooth 7 Output part 7a Pin 8 Housing 9 Output pin 10, 11, 15, 16 Tapered roller bearing 13 Bolt 14 Ring part

Claims (2)

A housing;
A hollow camshaft comprising an eccentric cylindrical portion and rotatably supported with respect to the housing;
A toothed disk that is abutted and driven by an eccentric cylindrical portion according to the rotation of the hollow cam shaft and revolves around the axis of the hollow cam shaft;
An internal tooth body having internal teeth that mesh with external teeth provided in the toothed disk;
A plurality of pin portions extending around the hollow cam shaft from the housing and supporting the toothed disk so as to be capable of revolving,
The pin part is supported at both ends by a housing, and the two toothed disks are provided,
The speed reducer, wherein the hollow camshaft and the toothed disk are rotatably supported by a needle bearing.   The speed reducer according to claim 1, wherein the speed reducer is used in a robot.

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