JP2017166549A - Unit type undulation gear device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an increasing in axis length to be restricted and attain a simple process of manufacture and reduction in manufacturing cost of a unit type undulation gear speed reducer provided with a bearing for supporting an internal gear and an external gear under a state in which they can be rotated in relative manner.SOLUTION: An undulation gear speed reducer 4 is configured in such a way that a boss 22c of an external gear 22 and an inner ring side fastening part 24a of an inner ring 29 of a bearing 27 are held between a bearing housing 14 and a nut 15, a male thread part 14d of the bearing housing 14 is engaged with thread at a thread hole 15a of the nut 15, and the boss 22c and the inner ring side fastening part 24a are fastened and fixed from a direction of a center axis line 1a. A thread processing for the inner ring 29 can be eliminated and it becomes unnecessary to arrange a machining clearance at the inner ring 29 for thread processing. It is possible to restrict increasing in size in a direction of the center axis line 1a of the inner ring 29 and this is advantageous for making average size of the axis length.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wave gear device, and more particularly to a unit type wave gear device including a bearing that supports a rigid internal gear and a cup-shaped flexible external gear in a relatively rotatable state.

  In a unit type wave gear device having a cup-shaped external gear, an inner ring of a bearing supporting both gears in a relatively rotatable state is fixed to a boss of the external gear, and the outer ring is connected to an internal gear. It is fixed to a device housing that is fixed or integrally formed. The inner ring is generally fixed to the boss of the external gear by bolting. The bolt is fastened from the inside of the external gear so as to penetrate the boss and the inner ring of the external gear in the axial direction. Patent Document 1 describes a wave gear unit having a structure in which an external gear and an inner ring are fastened by bolting.

  When the inner ring and the external gear cannot be fastened and fixed by bolting from the inside of the external gear, a fastening and fixing structure by screwing is used. Screw processing is performed on the outer peripheral surface portion of the boss of the external gear and the inner peripheral surface portion of the inner ring, and both are fastened by screwing. Patent Document 2 describes a wave gear unit having a structure in which an inner ring is fastened and fixed to a boss of an external gear by screwing.

JP 2014-74450 A JP 2002-21866 A

  Here, as shown in FIG. 2 of Patent Document 2, in order to perform threading on the inner peripheral surface of the inner ring with a step, a predetermined clearance is required in the axial direction from the step surface. If such a length for escape is omitted, it is advantageous for a flat unit type wave gear device having a short axial length.

  In addition, when the inner ring and the external gear boss are fastened and fixed by screwing, the inner ring and the boss need to be threaded, and the external gear has an irregular shape because the boss is provided with a threaded portion. Furthermore, processing (hexagonal hole processing, pin hole processing) for applying a fastening force for screwing to the inner ring and the external gear is necessary. If these can be made unnecessary, the production of the inner ring and the external gear can be simplified correspondingly, and the production cost can be reduced.

  In view of these points, the problem of the present invention is that the inner ring of the bearing can be connected to the external gear by a screwing structure that can suppress an increase in the shaft length, simplify the production, and reduce the production cost. An object is to provide a unit type wave gear device fastened to a boss.

In order to solve the above problems, the present invention provides:
In a unit type wave gear device including a bearing such as a cross roller bearing that supports a rigid internal gear and a cup-shaped flexible external gear so as to be relatively rotatable,
An inner ring side fastening portion formed on the inner ring of the bearing;
A first fastening member and a second fastening member fastened and fixed in a state of sandwiching the boss of the external gear and the inner ring side fastening portion from both sides in the direction of the device axis,
Have
When viewed along the direction of the device axis, the first fastening member is located outside the external gear and the second fastening member is located inside the external gear with respect to the boss. ,
The first fastening member includes a screw hole;
The second fastening member includes a screw portion that passes through a central through hole formed in the boss and the inner ring side fastening portion and is screwed into the screw hole.

  In the present invention, the boss of the external gear and the inner ring side fastening portion formed on the inner ring of the bearing are sandwiched between the first and second fastening members, and the first and second fastening members are screwed together to The inner ring side fastening portion is fastened and fixed from the direction of the apparatus axis. It is not necessary to thread the inner ring of the bearing, and it is not necessary to provide a machining clearance for threading the inner ring. As a result, an increase in the dimension of the inner ring in the direction of the device axis can be suppressed, which is advantageous for flattening the device.

  Further, since it is not necessary to thread the bearing into the inner ring and thread the external gear boss, these parts can be easily manufactured. Further, since screw machining is not required, it is not necessary to use a deformed external gear. Therefore, it is advantageous in terms of common parts and leads to a reduction in manufacturing cost of the apparatus.

  Here, the unit type wave gear device of the present invention includes an input shaft to which rotation from a rotational drive source such as a motor is input to a wave generator, and one end of the input shaft is connected to the external gear. There may be a support bearing that supports the inside. In this case, a bearing housing holding a support bearing can be used as the second fastening member used for fastening and fixing the boss of the external gear and the inner ring of the bearing.

It is a schematic sectional drawing which shows the flat actuator to which this invention is applied. It is a partial expanded sectional view of the flat actuator of FIG.

  Hereinafter, an embodiment of a unit type wave gear device to which the present invention is applied will be described with reference to the drawings. The present embodiment relates to a flat actuator having a configuration in which a unit type wave gear device is used as a speed reducer and assembled to a motor, but the present invention is not limited to the embodiment.

  As shown in FIG. 1, the flat actuator 1 includes a motor 2, an encoder 3 that detects the rotation state of the motor 2, and a unit-type wave gear device 4 (hereinafter, “wave gear reducer 4”) that decelerates the motor rotation. Called).

  The motor 2 includes a stator assembly 6 and a rotor assembly 7 which are coaxially incorporated inside a motor case 5 having an end plate portion 5a and a cylindrical body portion 5b. The stator assembly 6 includes a stator coil 9 wound around each salient pole of a stator core 8 attached to the inner peripheral surface of the motor case 5. The rotor assembly 7 includes a rotor shaft 10, a rotor disk 11 that rotates integrally with the rotor shaft 10, and a rotor magnet 12 that is attached to the outer periphery of the rotor disk 11.

The wave gear reducer 4 includes a reducer case 20 fixed to a motor case 5, a rigid internal gear 21 formed integrally with the reducer case 20, and a cup shape coaxially disposed inside the reducer case 20. Flexible external gear 22 and an elliptical wave generator 2 fitted inside the outer gear 22
3 is provided. The wave gear reducer 4 includes an input shaft portion 10 </ b> A fixed to the wave generator 23 and an output shaft portion 24 fixed to the external gear 22. The input shaft portion 10 </ b> A is integrally formed with the rotor shaft 10.

  Between the internal gear 21 and the external gear 22, a bearing 27, in this example, a cross roller bearing is disposed. The external gear 22 is supported by the bearing 27 so as to be rotatable relative to the internal gear 21. Inside the external gear 22, a support bearing 13 that supports the input shaft portion 10 </ b> A integrally formed with the rotor shaft 10, in this example, a combined angular ball bearing is disposed. The support bearing 13 supports the input shaft portion 10A, and thus the rotor shaft 10 in a cantilever state.

  In this example, a combination angular contact ball bearing is used as the support bearing 13. Of course, other types of rolling bearings may be used as the support bearing 13. For example, a double row deep groove ball bearing or the like can be used, and the support bearing 13 is not limited to a combination angular ball bearing.

  FIG. 2 is an enlarged partial sectional view of the flat actuator 1. The structure of each part will be described with reference to FIGS. First, the rotor shaft 10 of the motor 2 is disposed along the central axis 1 a (device axis) of the flat actuator 1. The rotor shaft 10 is an input shaft portion 10 </ b> A of the wave gear reducer 4 in which the portion on the output side first shaft end portion 10 a side is located inside the external gear 22, and is freely rotatable by the support bearing 13. It is supported. A portion on the second shaft end portion 10 b side that is the other counter-output end (rear end) of the rotor shaft 10 protrudes from the opening end of the external gear 22. The second shaft end portion 10b protrudes outward from the end plate portion 5a on the rear end side of the motor case 5, and a rotating portion (not shown) of the encoder 3 is fixed to the protruding portion in a coaxial state. Yes.

  A rotor disk 11 is coaxially fixed to a portion of the rotor shaft 10 on the side of the second shaft end portion 10b protruding from the opening end of the external gear 22. The outer peripheral edge of the rotor disk 11 is a cylindrical portion 11a extending toward the wave gear reducer 4, and a rotor magnet 12 is attached to the outer peripheral side of the cylindrical portion 11a. The rotor magnet 12 is opposed to the stator coil 9 of the stator assembly 6 attached to the inner peripheral surface portion of the cylindrical body 5b of the motor case 5 with a certain gap.

  On the other hand, in the wave gear reducer 4, the cup-shaped external gear 22 includes a cylindrical body 22 a that can be bent in the radial direction and a radial direction from the end of the body 22 a opposite to the motor 2. A disc-shaped diaphragm 22b extending inward, a rigid annular boss 22c integrally formed on the inner peripheral edge of the diaphragm 22b, and an opening end side opening on the motor 2 side in the body portion 22a. And external teeth 22d formed on the outer peripheral surface portion.

  In the input shaft portion 10 </ b> A of the rotor shaft 10 positioned inside the external gear 22, a rigid cam plate 23 a of the wave generator 23 is integrally formed at a portion of the motor side with respect to the support bearing 13. The rigid cam plate 23a has an outer peripheral surface with an elliptical contour, and a wave generator bearing 23b is mounted on the outer peripheral surface. The portion of the external teeth 22d on the open end side of the external gear 22 is bent elliptically by the wave generator 23 and partially meshed with the internal teeth 21d of the internal gear 21 arranged on the outer peripheral side thereof. ing.

As shown in FIG. 1, the speed reducer case 20 has an outer cylindrical portion 20a fixed to the inner peripheral surface of the cylindrical body 5b of the motor case 5, and a radius from the motor side end of the outer cylindrical portion 20a. From the outer peripheral side disk part 20b extending inward in the direction, the inner peripheral side cylindrical part 20c extending from the inner peripheral part of the outer peripheral side disk part 20b to the motor side, and the end of the inner peripheral side cylindrical part 20c on the motor side And an inner peripheral disk portion 20d extending inward in the radial direction.

  The rotor shaft 10 extends through the central portion of the inner peripheral disk portion 20d of the speed reducer case 20. Further, the inner circumferential side disk portion 20 d is located between the wave generator 23 and the rotor disk 11 of the motor 2. A space between the inner peripheral disk portion 20d and the rotor shaft 10 is sealed with an oil seal 26. This prevents the grease from leaking out from the wave gear reducer 4 side to the motor 2 and encoder 3 side.

  As shown in FIG. 1, the internal gear 21 and the external gear 22 of the wave gear reducer 4 are supported in a relatively rotatable state via a bearing 27. The outer ring 28 of the bearing 27 is mounted and fixed from the opening 5 c side of the motor case 5 to the inside of the outer peripheral side cylindrical portion 20 a of the reduction gear case 20. The inner ring 29 of the bearing 27 is mounted from the opening 5 c side of the motor case 5 and is integrally formed on the outer peripheral portion of the output shaft portion 24.

(Fastening structure for external gear and inner ring)
Here, a disc-shaped inner ring side fastening portion 24 a having a predetermined width extending inward in the radial direction is formed on the inner peripheral surface of the inner ring 29 of the bearing 27. The inner ring side fastening portion 24a and the boss 22c of the external gear 22 are fastened and fixed coaxially. These fastening and fixing structures will be described below.

  As shown in FIG. 2, the fastening and fixing structure includes a nut 15 as a first fastening member that fastens and fixes the boss 22c and the inner ring side fastening portion 24a from both sides in the direction of the central axis 1a, It is comprised from the bearing housing 14 as 2 fastening members. The bearing housing 14 holds the support bearing 13.

  The inner peripheral side portion of the disc-shaped inner ring side fastening portion 24a is in contact with the disc-shaped boss 22c from the side opposite to the motor 2 (outside of the external gear 22) in the direction of the central axis 1a. Yes. The nut 15 (first fastening member) is in contact with the inner ring side fastening portion 24a from the side opposite to the boss 22c in the direction of the central axis 1a. The bearing housing 14 (second fastening member) is in contact with the boss 22c on the side opposite to the inner ring side fastening portion 24a (inside the external gear 22) in the direction of the central axis 1a. The bearing housing 14 is screwed into the nut 15 through a central through hole formed in the boss 22c and the inner ring side fastening portion 24a.

  The bearing housing 14 includes a housing main body portion 14a on which the support bearing 13 is mounted, and a small-diameter mounting cylindrical portion 14b extending coaxially from an end portion of the housing main body portion 14a opposite to the motor 2. ing. An annular step 14c is formed between the housing main body 14a and the mounting cylinder 14b.

  The mounting cylindrical portion 14b extends through the center through hole of the boss 22c of the external gear 22 and the center through hole defined by the inner peripheral surface of the inner ring side fastening portion 24a of the inner ring 29 of the bearing 27. Yes. A portion of the mounting cylindrical portion 14b that protrudes from the center through hole of the inner ring 29 opposite to the motor 2 is a male screw portion 14d having a male screw cut on the outer peripheral surface. The male screw portion 14 d is fixed by screwing into the screw hole 15 a of the nut 15.

  Therefore, in the state where the inner ring side fastening portion 24a of the inner ring 29 of the bearing 27 and the boss 22c of the external gear 22 are sandwiched between the annular step portion 14c of the bearing housing 14 and the nut 15, the central axis 1a Fastened from the direction.

As shown in FIG. 2, the outer ring of the support bearing 13 is held between the inner end surfaces of the annular step portions 14 c and 14 e on both sides of the housing main body portion 14 a in the bearing housing 14. Further, the inner ring of the support bearing 13 is held between an inner ring stopper step surface 10 c formed on the outer peripheral surface of the input shaft portion 10 </ b> A and an annular bearing inner ring retainer 31.

  The bearing inner ring retainer 31 is held in contact with the inner ring of the support bearing 13 by a cylindrical nut 32 attached to the first shaft end portion 10a of the input shaft portion 10A. That is, the first shaft end portion 10a of the input shaft portion 10A is located inside the mounting cylindrical portion 14b of the bearing housing 14, and an annular bearing inner ring presser 31 is mounted thereon. A cylindrical nut 32 is screwed and fixed to the first shaft end portion 10 a, and the bearing inner ring retainer 31 is held in contact with the inner ring of the support bearing 13 by the cylindrical nut 32. A set screw 33 for preventing loosening is screwed into the cylindrical nut 32 and fixed.

  In the flat actuator 1 having this configuration, when the motor 2 is driven and the rotor shaft 10 is rotated, the wave generator 23 of the wave gear reducer 4 formed integrally therewith is rotated. When the wave generator 23 rotates, the meshing positions of the external gear 22 with respect to the internal gear 21 (positions at both ends of the elliptical long axis) move in the circumferential direction. For example, since the number of teeth of the external gear 22 is two less than that of the internal gear 21, the external gear 22 is relative to the internal gear 21 by a difference in the number of teeth while the wave generator 23 rotates once. Rotate. Since the internal gear 21 is fixed, the reduced speed rotation (actuator output) is taken out from the output shaft portion 24 of the external gear 22.

  On the side of the wave gear reducer 4, the fastening structure of the boss 22c of the external gear 22 and the inner ring 29 of the bearing 27 can be shortened in the direction of the central axis as compared with the conventional screwing type. Further, the rotor shaft 10 in which the input shaft portion 10 </ b> A is integrally formed is supported in a cantilever state by a support bearing 13 disposed inside the cup-shaped external gear 22. Since the rotor shaft 10 is supported by utilizing the internal space of the external gear 22, a space for arranging a bearing for supporting the rotor shaft 10 protruding from the external gear 22 is ensured. There is no need. Therefore, the flat actuator 1 having a short shaft length can be realized.

DESCRIPTION OF SYMBOLS 1 Flat actuator 1a Axis 2 Motor 3 Encoder 4 Wave gear reducer 5 Motor case 5a End plate part 5b Cylindrical trunk | drum 5c Opening part 6 Stator assembly 7 Rotor assembly 8 Stator core 9 Stator coil 10 Rotor shaft 10a 1st shaft end part 10b Second shaft end portion 10c Stepped surface 10A Input shaft portion 11 Rotor disk 11a Cylindrical portion 12 Rotor magnet 13 Support bearing 14 Bearing housing (second fastening member)
14a Housing body portion 14b Mounting cylindrical portion 14c Annular step portion 14d Male screw portion 14e Annular step portion 15 Nut (first fastening member)
15a Screw hole 20 Reducer case 20a Outer peripheral side cylindrical part 20b Outer peripheral side disk part 20c Inner peripheral side cylindrical part 20d Inner peripheral side disk part 21 Internal gear 21d Internal tooth 22 External tooth 22a Body 22b Diaphragm 22c Boss 22d External tooth 23 Wave generator 23a Rigid cam plate 23b Wave generator bearing 24 Output shaft portion 24a Inner ring side fastening portion 26 Oil seal 27 Bearing 28 Outer ring 29 Inner ring 31 Bearing inner ring retainer 32 Cylindrical nut 33 Set screw

Claims (3)

In a unit type wave gear device including a bearing that supports a rigid internal gear and a cup-shaped flexible external gear so as to be relatively rotatable,
An inner ring side fastening portion formed on the inner ring of the bearing;
A first fastening member and a second fastening member fastened and fixed in a state of sandwiching the boss of the external gear and the inner ring side fastening portion from both sides in the direction of the device axis,
Have
When viewed along the direction of the device axis, the first fastening member is located outside the external gear and the second fastening member is located inside the external gear with respect to the boss. ,
The first fastening member includes a screw hole;
The said 2nd fastening member is a unit type wave gear apparatus provided with the thread part which penetrates the center through hole formed in the said boss | hub and the said inner ring | wheel side fastening part, and is screwed in the said screw hole. In claim 1,
An input shaft;
A support bearing that supports one shaft end of the input shaft inside the external gear;
Have
The second fastening member is a unit type wave gear device which is a bearing housing holding the support bearing. In claim 1 or 2,
The unit type wave gear device, wherein the bearing is a cross roller bearing.