JP2005249001A - Speed reducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a speed reducer, reduced in size by a comparatively simple mechanism. <P>SOLUTION: This speed reducer includes: a hollow cylindrical shaft part 6 rotatably supported in slit cases 2, 3; a worm gear mechanism 5 for reducing the rotation of a motor and transmitting the same to the cylindrical shaft part 6; an eccentric shaft part 20 formed with eccentricity to the axis X of rotation of the cylindrical shaft part 6; a differential gear mechanism 7 having a differential external gear 22 fixed to the cases 2, 3 and a differential internal gear 21 externally journaled to the eccentric shaft part 20 and circumscribing the differential external gear 22 to mesh therewith; a differential phase takeout part 8 for taking out the phase lag of the differential internal gear 21 corresponding to a difference in number of teeth of the differential gear mechanism 7; an output shaft part 9 passed through the cylindrical shaft part 6 with both ends extended to the outside of the cases 2, 3 and rotatably supported on the cases 2, 3; and a transmission part 10 for transmitting the phase lag to the output shaft part 9. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a reduction gear, and more particularly to a double-shaft output type reduction gear provided with a differential gear mechanism.

  Conventionally, a reduction gear using a differential gear mechanism has been proposed. According to this reduction gear, since it can be configured with a relatively simple mechanism with a large reduction ratio, it is used in many devices.

  By the way, in this kind of reduction gear, all are single axis output types in which the output shaft portion extends only to one side. For this reason, for example, in a device in which rotational loads are arranged on both ends, if such a reduction gear is to be employed, a mechanism for connecting the output shaft portion of the reduction gear and the two rotation loads, that is, the output of the reduction gear is set to two. A transmission mechanism for transmitting to each of the rotational loads is required, and the internal structure of the device becomes complicated. Further, in the single-shaft output type, the output shaft portion is in a cantilever state, so that it is likely to have an effect on torsion and bending moment. Therefore, for such devices, it is desired to use a double-shaft output type speed reducer in which the output shaft portion extends from both sides.

  The above prior art is naturally performed by those skilled in the art, and the applicant is not aware of a document describing the prior art.

  However, in the double-shaft output type speed reducer, the output shaft portion is disposed so as to penetrate the case, and therefore, the arrangement positions of various mechanisms that must be built in the case are restricted. In particular, in a reduction gear including a differential gear mechanism, the output shaft portion is disposed at the center of the differential gear mechanism, which makes it difficult to dispose a transmission mechanism or the like for making the differential gear mechanism differential. There is a concern that the internal structure of the speed reducer becomes complicated and the size of the device increases.

  Therefore, in view of the above situation, the present invention has an object to provide a double-shaft output type reduction gear having a differential gear mechanism, which can be reduced in size with a relatively simple mechanism. It is.

  The speed reducer according to the present invention includes a “case, a hollow cylindrical shaft portion rotatably supported in the case, and a first transmission that transmits the rotation of the motor to the cylindrical shaft portion and rotates the cylindrical shaft portion. Means, an eccentric shaft portion formed eccentrically with respect to the rotation axis of the cylindrical shaft portion, a differential external gear fixed to the case, and a shaft fitted on the eccentric shaft portion. A differential gear mechanism having a differential internal gear that is supported and externally meshed with the differential external gear, and the differential internal gear according to a difference in the number of teeth of the differential external gear and the differential internal gear. A differential phase extraction portion for extracting a phase shift, an output shaft portion that is inserted into the cylindrical shaft portion, has both ends extended to the outside of the case, and is rotatably supported with respect to the case; and the differential The phase shift extracted by the phase extraction section is transmitted to the output shaft section, and the output shaft section is rotated. That the second; and a transmission unit "is intended.

  Here, the “first transmission means” may be a mechanism that directly transmits the rotation of the motor to the cylindrical shaft portion, or may be a mechanism that decelerates and transmits the rotation to the cylindrical shaft portion. The “second transmission means” may be a mechanism that directly transmits the phase shift extracted by the differential phase extraction unit to the output shaft unit, or a mechanism that decelerates and transmits the output to the output shaft unit. Good. Note that a gap is formed between the cylindrical shaft portion and the output shaft portion, and is arranged so as not to contact each other.

  According to the speed reducer of the present invention, the rotation of the motor is transmitted to the cylindrical shaft portion via the first transmission means, and the cylindrical shaft portion rotates at a predetermined rotational speed. Then, the eccentric shaft part eccentric with respect to the rotation axis of the cylindrical shaft part also rotates at a predetermined rotational speed. Since the differential internal gear is externally fitted and pivotally supported on the eccentric shaft portion, the differential internal gear revolves around the rotation axis of the cylindrical shaft portion. At this time, since the differential internal gear revolves while externally meshing with the differential external gear fixed to the case, the differential internal gear revolves by the number of teeth of the differential external gear (one revolution). Then, the phase of the differential internal gear is shifted by the difference in the number of teeth of both gears (for example, one tooth). That is, the differential internal gear rotates (spins) by the difference in the number of teeth. This phase shift is extracted by the differential phase extraction unit and transmitted to the output shaft unit via the second transmission means.

  The cylindrical shaft portion for revolving the differential internal gear is formed hollow, and the output shaft portion is inserted into the cylindrical shaft portion. For this reason, even if both ends of the output shaft portion are extended to the outside of the case, the output shaft portion can be disposed without hindering the cylindrical shaft portion for revolving the differential internal gear.

  By the way, in the speed reducer of the present invention, “the first transmission means is connected to the motor and connected to the outer peripheral surface of the cylindrical shaft portion and the worm supported rotatably with respect to the case. It is comprised of a worm gear mechanism having a worm wheel meshing with the worm ”.

  According to this, the rotation of the motor is decelerated by the worm gear mechanism, and then the output of the worm gear mechanism is transmitted to the differential gear mechanism via the cylindrical shaft portion. That is, since the rotation of the motor is transmitted to the output shaft portion via the two reduction mechanisms, a high reduction ratio can be obtained.

  In the speed reducer according to the present invention, it is possible to adopt a configuration in which “the tooth tip and the tooth groove that mesh with each other in the differential internal gear and the differential external gear both have an arc shape”.

  Here, the arc-shaped portion is at least a portion in contact with each other, and when the tooth tip of the differential internal gear and the tooth groove of the differential external gear are formed in an arc shape, the tooth of the differential internal gear In some cases, the teeth of the groove and the differential external gear are formed in an arc shape.

  According to this, since the arcuate surfaces in the differential gear mechanism are engaged with each other while being in contact with each other, it becomes possible to bring backlash close to zero, reducing the generation of noise due to the engagement, and improving the strength. Can do.

  As described above, according to the reduction gear device of the present invention, the transmission mechanism for revolving the differential internal gear is formed hollow, and the output shaft portion is inserted through the transmission mechanism. The output type speed reduction device can be realized with a relatively simple mechanism, and the size of the device can be reduced.

  Hereinafter, a reduction gear according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. 1 is a cross-sectional view showing the configuration of the reduction gear, FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line BB in FIG. The speed reducer 1 of this embodiment is a double-shaft output type speed reducer that decelerates and outputs the rotation of a motor, and is divided into a first case 2 and a second case 3 (hereinafter referred to as cases 2 and 3). And a mechanism portion accommodated in these cases 2 and 3. Here, the combination of the first case 2 and the second case 3 corresponds to the case of the present invention.

  The mechanism includes a worm gear mechanism 5 that is connected to the small motor 4 and decelerates the rotation of the motor 4, and a cylindrical shaft portion 6 that is rotatably supported in the cases 2 and 3 and connected to the output side of the worm gear mechanism 5. A differential gear mechanism 7 that further decelerates the rotation of the cylindrical shaft portion 6, a differential phase extraction portion 8 that extracts a phase shift from the differential gear mechanism 7, and both ends that are rotatably supported in the cases 2 and 3. The output shaft portion 9 extends to the outside of the cases 2 and 3 and the transmission portion 10 that transmits the phase shift extracted by the differential phase extraction portion 8 to the output shaft portion 9. Here, the worm gear mechanism 5 corresponds to the first transmission means of the present invention, and the transmission portion 10 corresponds to the second transmission means of the present invention.

  Each configuration will be specifically described. As shown in FIG. 2, the worm gear mechanism 5 includes a worm 13 having one end directly connected to the rotating shaft 4 a of the motor 4 and the other end pivotally supported by the first case 2 via a bearing 12, and a cylindrical shaft portion 6. It is comprised from the worm wheel 14 externally fitted and connected with the outer peripheral surface. The worm 13 is a screw-shaped gear having one or a plurality of teeth, and the worm wheel 14 is engaged with a part of the circumference of the worm 13 so as to be in rotation with respect to the rotation axis of the worm 13. A gear that rotates at a right angle. This worm gear mechanism 5 enables a relatively large speed reduction. Further, as shown in FIG. 1, a fastening support portion 15 for fastening to the cylindrical shaft portion 6 is attached to the worm wheel 14 by a connecting bolt 16. The fastening support portion 15 has a pair of semicircular arc shapes in which a part of the cylindrical shape is divided into two in the axial direction, and the inner surface thereof is pressed against the cylindrical shaft portion 6 by fastening the fastening bolts 17. It is. As shown in FIG. 1, the worm wheel 14 is positioned in the left-right direction on the paper surface by a substantially cylindrical spacer 18.

  On the other hand, the cylindrical shaft portion 6 is a hollow member whose both ends are open, and is supported by the cases 2 and 3 via bearings 19. Further, an eccentric shaft portion 20 that is eccentric with respect to the rotation axis X of the cylindrical shaft portion 6 is integrally formed on one end side (right side of the drawing) of the cylindrical shaft portion 6 (see FIG. 3).

  As shown in FIGS. 1 and 3, the differential gear mechanism 7 includes a differential external gear 22 fixed to the cases 2 and 3, and a differential internal gear 21 disposed in the differential external gear 22. It is configured. The differential internal gear 21 is externally fitted to the eccentric shaft portion 20 via a bearing 23, and revolves around the rotation axis X when the cylindrical shaft portion 6 rotates. A plurality of teeth 24 are formed on the outer peripheral surface of the differential internal gear 21, and the differential internal gear 21 is externally meshed with the teeth 26 formed on the inner peripheral surface of the differential external gear 22. While revolving. Here, when the number of teeth of the differential internal gear 21 and the number of teeth of the differential external gear 22 are equal, the phase of the differential internal gear 21 will not shift even if the differential internal gear 21 revolves. In the present invention, the number of teeth of the differential internal gear 21 and the number of teeth of the differential external gear 22 are set to be different from each other, and the phase of the differential internal gear 21 is shifted when revolving. That is, when the differential internal gear 21 revolves by the number of teeth of the differential external gear 22 (one revolution), the differential internal gear 21 rotates (spins) by the difference in the number of teeth of both gears. . The difference in the number of teeth between the differential internal gear 21 and the differential external gear 22 is not particularly limited, but in this example, the difference in the number of teeth is set to “1”.

  The differential external gear 22 is formed with a plurality of mounting holes 27 drilled at a predetermined interval in the circumferential direction, and the differential external gear 22 is a bolt that is fastened through the mounting holes 27 ( (Not shown).

  Further, the differential internal gear 21 is formed with a plurality of holes 25 formed at equal intervals in the circumferential direction, and a part of the differential phase extraction part 8 is inserted into each hole 25. ing. The differential phase extraction portion 8 includes a transmission pin 29 and a transmission sleeve 30 attached to one end side of the transmission pin 29, and a portion where the transmission sleeve 30 is attached is inserted into the hole 25. . The diameter of the transmission sleeve 30 is smaller than the inner diameter of the hole 25. Specifically, even when the differential internal gear 21 revolves around the rotation axis X, the size is set such that the inner peripheral wall of the hole 25 does not press the transmission sleeve 30. According to this, the transmission pin 29 and the transmission sleeve 30 can take out only the rotation (spinning) of the differential internal gear 21 without being affected by the revolution of the differential internal gear 21.

  As shown in FIG. 1, the transmission unit 10 is connected to the boss 35 by press-fitting the other end side (the right side in the drawing) of the plurality of transmission pins 29 and the connection bolt 37 to the boss 35, and the tightening bolt 38 outputs the output shaft. The fastening boss 36 is fastened to the portion 9. The configuration of the fastening boss 36 is the same as that of the fastening support portion 15.

  The output shaft portion 9 is pivotally supported with respect to the cases 2 and 3 via bearings 32 so that the rotation (phase shift) of the differential internal gear 21 is transmitted via the boss 35 and the fastening boss 36. It is configured. A slight gap is formed between the inner peripheral surface of the cylindrical shaft portion 6 and the outer peripheral surface of the output shaft portion 9. In the figure, 33 is an oil seal for preventing leakage of oil applied to each bearing and each gear.

  Next, the operation of the speed reduction device 1 of the present embodiment will be described. When the rotating shaft 4a of the motor 4 rotates, the worm 13 directly connected to the rotating shaft 4a rotates, and the worm wheel 14 meshed with the rotating shaft 4a and the cylindrical shaft portion 6 connected to the worm wheel 14 are rotated. At this time, the rotation of the motor 4 is decelerated by the meshing of the worm 13 and the worm wheel 14.

  When the cylindrical shaft portion 6 rotates, the differential internal gear 21 fitted around the eccentric shaft portion 20 revolves around the rotation axis X of the cylindrical shaft portion 6. At this time, since the tooth portion 24 of the differential internal gear 21 is externally meshed with the tooth portion 26 of the differential external gear 22, the differential internal gear 21 rotates by the difference in the number of teeth of both the gears 21 and 22.

  The rotation (phase shift) of the differential internal gear 21 is taken out by the transmission pin 29 and the transmission sleeve 30 and transmitted to the output shaft portion 9 through the boss 35 and the tightening boss 36. As a result, the output shaft portion 9 rotates at the rotational speed reduced by the differential gear mechanism 7.

  As described above, according to the reduction gear 1 described above, the hollow cylindrical shaft portion 6 is used as a transmission mechanism for revolving the differential internal gear 21, and the output shaft portion 9 is disposed using the internal space. Yes. For this reason, even if both ends of the output shaft portion 9 are extended to the outside of the cases 2 and 3, the output shaft portion 9 can be disposed without hindering the worm gear mechanism 5. Therefore, the internal mechanism is simplified, and the double-shaft output type reduction gear 1 including the differential difference gear mechanism 7 can be realized by a relatively simple mechanism, and the apparatus can be reduced in size.

  Further, according to the reduction gear 1 described above, the rotation of the motor 4 is decelerated by the worm gear mechanism 5 and then further decelerated by the differential gear mechanism 7, so that a high reduction ratio can be obtained. For example, in this example, the rotational speed 6500 rpm of the motor 4 can be reduced to 2.26 rpm. Since the worm 13 and the worm wheel 14 mesh with each other at right angles to each other, the rotation shaft of the worm wheel 14 fitted on the outer peripheral surface of the cylindrical shaft portion 6 (that is, the rotation of the cylindrical shaft portion 6). The axis X) and the rotation axis of the worm 13 are perpendicular to each other. That is, since the rotating shaft 4a of the motor 4 and the output shaft portion 9 are perpendicular to each other, even if the output shaft portion 9 is disposed so as to penetrate the cases 2 and 3, the output shaft portion 9 and the motor 4 Can be avoided. Therefore, the apparatus can be further downsized.

  The present invention has been described with reference to preferred embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the present invention as described below. And design changes are possible.

  That is, in the reduction gear 1 of the present embodiment, the worm gear mechanism 5 is interposed between the motor 4 and the cylindrical shaft portion 6, and the rotation reduced by the worm gear mechanism 5 is transmitted to the cylindrical shaft portion 6. However, it may be transmitted via a speed reduction mechanism other than the worm gear mechanism 5, or the rotation of the motor 4 may be transmitted to the cylindrical shaft portion 6 as it is.

  Further, in the reduction gear 1 of the present embodiment, the tooth portions 24 and 26 in the differential internal gear 21 and the differential external gear 22 are those of a generally used tooth profile, but FIG. As shown in FIG. 4, the tooth groove 42 in the tooth portion 41 of the differential internal gear 40 and the tooth tip 45 in the tooth portion 44 of the differential external gear 43 are formed in a semicircular arc shape, and the arc portions are brought into contact with each other. You may make it mesh. According to this, as compared with the gears 21 and 22, it is possible to ensure smooth meshing without requiring a setting of a dislocation coefficient and a highly accurate surface finish. As a result, the backlash (gap provided between the tooth portions meshed to facilitate the rotation of the gear) can be brought close to zero, noise generation due to meshing is reduced, and strength is increased. Can be improved. Although not shown, the same effects can be obtained when the tooth tips of the tooth portions of the differential internal gear and the tooth grooves of the tooth portions of the differential external gear are formed in an arc shape.

  In the speed reduction device 1 of the present embodiment, the eccentric shaft portion 20 is formed integrally with the cylindrical shaft portion 6, but may be formed by another member and connected. However, if they are integrally formed as in this example, the structure is further simplified because the transmission mechanism between the cylindrical shaft portion 6 and the eccentric shaft portion 20 becomes unnecessary.

It is sectional drawing which shows the structure of a reduction gear. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is explanatory drawing which shows the other example of the differential external gear and differential internal gear in a differential gear mechanism.

Explanation of symbols

1 Reduction gear 2 First case (case)
3 Second case (case)
4 Motor 5 Worm gear mechanism (first transmission means)
6 cylindrical shaft portion 7 differential gear mechanism 8 differential phase extraction portion 9 output shaft portion 10 transmission portion (second transmission means)
13 Worm 14 Worm wheel 20 Eccentric shaft 21, 21 Differential internal gear 22, 43 Differential external gear 42 Tooth groove 45 Tooth tip

Claims (3)

Case and
A hollow cylindrical shaft portion rotatably supported in the case;
First transmission means for transmitting rotation of the motor to the cylindrical shaft portion and rotating the cylindrical shaft portion;
An eccentric shaft portion formed eccentric to the rotation axis of the cylindrical shaft portion;
A differential external gear fixed to the case; and a differential gear mechanism having a differential internal gear that is externally fitted to the eccentric shaft and is externally engaged with the differential external gear.
A differential phase extraction portion for extracting a phase shift of the differential internal gear according to a difference in the number of teeth of the differential external gear and the differential internal gear;
An output shaft that is inserted into the cylindrical shaft and has both ends extended to the outside of the case and supported rotatably with respect to the case;
And a second transmission means for transmitting the phase shift extracted by the differential phase extraction section to the output shaft section and rotating the output shaft section.   The first transmission means includes a worm coupled to the motor and supported rotatably with respect to the case, and a worm coupled to the outer peripheral surface of the cylindrical shaft portion and meshing with the worm. The speed reducer according to claim 1, comprising a gear mechanism.   The reduction gear according to claim 1 or 2, wherein both the tooth tip and the tooth groove meshing with each other in the differential internal gear and the differential external gear have an arcuate shape.

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