JP2003240067A - Wave gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high reliable wave gear suitable for miniaturization which can easily be manufactured by a simplified structure and with reduced cost. <P>SOLUTION: A gear part 2 to be engaged with a circular spline is formed on one periphery of an opening of a shell part 1 composed of a pipe member of a tubular elastic element, and the other end (attachment part) 3 of the opening of the shell part 1 is fixed to, for example, a disc-like fixing member 4 by adhesion and welding, or caulking and press fitting, and the like, so as to form a flexible spline. The end 3 may be fixed to the fixing member 4 from the outside of the end 3 with a ring-like member by adhesion, welding, caulking, press fitting and the like while arranging the disc-like fixing member 4 inside the end 3. The end 3 is made thick when needed, and a curve-like (R) or plane- like (C) tapered part is provided on either one or both of inner and outer peripheries of the end 3 in a manner that the end gets thinner toward a direction of the gear part 2 for giving flexibility, whereby avoiding concentration of stress to the end 3. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wave gear device having a flexspline and a circular spline.

[0002]

2. Description of the Related Art A wave gear device is known for its large reduction ratio and high torque. FIG. 5A shows a structural example of a conventional wave gear device that is commercially available. The wave gearing is a circular spline 101 and a flexspline 102, which are two gears having slightly different numbers of teeth.
And a wave generator 103. The circular spline 101 is rigid and has teeth inside the circular ring at the same pitch as the flexspline 102 and slightly different (for example, two more) from the flexspline 102. The flex spline 102 has teeth on the outer periphery of a thin-walled, cup-shaped metal elastic body, and is flexed (elastically deformed) from the inside to an ellipse by the wave generator 103, and the circular spline is formed at two points in the major axis direction. Mesh with 101. The wave generator 103 has an elliptical cam as an inner ring, and a large number of balls are arranged between the inner ring and the outer ring that elastically deforms, and elastically deforms the outer ring into an elliptical shape through the balls as the inner ring rotates.

Here, for example, when the circular spline 101 is fixed and the wave generator 103 is rotated once clockwise, the flexspline 102 moves counterclockwise by the difference in the number of teeth (two). Therefore, when the wave generator 103 is rotated by a motor or the like, a rotation output greatly decelerated from the axis of the flexspline 102 can be obtained.

FIG. 5 (b) shows a cross-sectional view of the above-mentioned flexible flexspline as seen from the side. The conventional flexspline 4 has a flange 102 on the bottom of a tubular body 102a.
b and a diaphragm portion 102c are formed to form a cup shape, and a gear portion 102d that meshes with the circular spline is formed on the peripheral surface on the opening side. Flange part 1
There is a hole in the center of 02b, and the flange portion 104a
Is attached to the output shaft 104.

Since the flexspline is elastically deformed as described above, stress is applied to the corners of the body and the diaphragm and the joints between the diaphragm and the flange due to the elastic deformation. Several structures have been proposed to avoid such stress concentration and to resist fatigue fracture. As an example,
According to Japanese Patent No. 3032534, the body portion and the diaphragm portion are welded at the portion where the stress is the smallest in the calculation, and the welding separation between the body portion and the diaphragm portion due to fatigue fracture is prevented. In Japanese Utility Model Publication No. 6-40355, stress is absorbed by inflating the connecting portion between the body portion and the diaphragm portion to the outside. In addition, in actual exploitation Sho 61-173851,
The boundary between the flange and the diaphragm is gradually thickened toward the flange.

[0006]

However, the above conventional wave gear device is complicated in shape and structure and difficult to manufacture in any case, so that the cost is high and the flange portion of the flexspline is provided, which makes the device compact. It was not suitable for.

The present invention has been made to solve the above-mentioned problems of the prior art, and simplifies and simplifies the structure to facilitate manufacturing, reduces cost, has high reliability, and is small in size. It is an object of the present invention to provide a wave gear device that is suitable for commercialization.

[0008]

In order to achieve the above object, a wave gear device according to the present invention 1 is a wave gear device having a flexspline and a circular spline, wherein the circular elastic member is provided at one of the openings of the cylindrical elastic body. A flexspline is formed by forming a gear portion that meshes with the spline and fixing the other to a fixing member.

Alternatively, the fixing member is integrally formed with the output shaft.

Alternatively, at the time of flexspline deformation, the end portion of the cylindrical elastic body which is in contact with the fixing member is made thick and one or both of the inner end and the outer end is gradually thinned toward the gear portion when flexspline is deformed. The present invention is characterized in that a curved surface-shaped or flat-shaped tapered portion is provided in order to avoid the concentrated stress.

Alternatively, a curved or flat taper portion is provided on one or both of the inner and outer edges of the fixing member that is in contact with the tubular elastic body to avoid concentrated stress during flexspline deformation. Is characterized by.

Further, in order to achieve the above object, the wave gear device according to the second aspect of the present invention is a wave gear device having a flexspline and a circular spline, wherein the output shaft and the flexspline are integrally formed from one rod-shaped member. It is characterized by forming.

Alternatively, in the above-mentioned wave gear device, first, a gear portion is formed, then an outer side of the flexspline body is formed, and then the outward deformation of the body is restricted so that the inner and outer sides of the flexspline are output. It is characterized in that it is formed with a shaft.

According to the first aspect of the present invention, a simplified structure in which the tubular elastic body is fixed to the fixing member by eliminating the flange portion and the diaphragm portion which complicate and enlarge the shape and structure of the ordinary cup-shaped flexspline. By
It facilitates manufacturing, reduces cost, obtains high reliability, and enables miniaturization.

According to the second aspect of the present invention, the flange portion which complicates and enlarges the shape and structure of an ordinary cup-shaped flexspline is eliminated, and the flexspline and the output shaft are machined and formed from one rod-shaped member. The structure facilitates manufacturing, reduces cost, obtains high reliability, and enables miniaturization.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view of a flexspline showing an embodiment of the present invention 1. In this example, a gear portion 2 that meshes with a circular spline (not shown) is formed on one circumferential surface of an opening of a body 1 made of a tubular elastic tubular member, and the other end of the opening of the body 1 is formed. The portion (mounting portion) 3 is fixed to, for example, a disc-shaped fixing member (flange portion) 4 by adhesion, welding, crimping, press fitting, or the like to form a flexspline of a wave gear device. To fix the end portion 3 to the fixing member 4, the disc-shaped fixing member 4 is arranged inside the end portion 3,
Bonding, welding, caulking with a ring-shaped member from the outside of the end portion 3,
It may be performed by press fitting.

The end portion 3 has a wall thickness as necessary, and a curved surface (R) or flat surface (C) taper portion so that the end portion 3 is thinned toward the gear portion 2 to have flexibility. Are provided on the inner circumference and / or the outer circumference thereof to avoid stress concentration on the end portion 3. A metal is generally used as the tubular elastic body forming the body portion 1, but a reinforced resin or the like may be used together with the gear portion 2, and the material is not limited.

When the flexspline is rotated, the fixing member 4 is integral with the output shaft 5 as shown in FIG. 1, or the disc-shaped fixing member 4 is adhered or welded to the output shaft 5. Or, it shall be fixed with a detent and then by caulking or press fitting. When rotating the circular spline, the output shaft 5 is fixed to the side of the circular spline and is not connected to the fixing member 4. In this case, the fixing member 4 may be fixed to a case or the like, or the fixing member 4 may be a part of the case.

FIG. 2 is a sectional view of a flexspline showing another embodiment of the present invention 1. In this example, the configuration is the same as that of FIG. 1, but the way of attaching the body portion 1 to the fixing member 4 is different. That is, the end portion 3 is not thickened, the disc-shaped fixing member 4 is arranged inside the end portion 3, and the end portion 3 is bonded from the outer side of the end portion 3 with a ring-shaped member 6 by welding, caulking, press fitting, or the like. Fix the part 3.

Here, the fixing member 4 or the ring-shaped member (flex spline holder) 6 or the end portions 3 of both of them.
The boundary part that contacts with is curved (R) or planar (C)
And chamfered to provide a tapered portion. As a result, the free movement region of the body portion 1 can be widened, stress concentration on the end portion 3 can be avoided, and reliability is enhanced.

As described above, the simple structure in which the cylindrical elastic body is attached to the rigid fixing member by eliminating the diaphragm portion and the flange portion which complicate the shape and structure of the conventional flexspline. Therefore, it is extremely easy to manufacture, and it is easy to make small size.
Cost can be reduced.

FIG. 3 is a diagram showing an example of the structure of a motor with a wave gear device in which a wave gear device having the above-mentioned structure and effects is integrally incorporated, and FIG. 7B is a sectional view taken along the line AA ′ in FIG. In this example,
This is an example of a structure in which a roller for wave generation is directly attached to an inner rotor type motor instead of a complicated and expensive wave generator. The example of FIG. 3 is an example, and it goes without saying that the present wave gear device can be applied to an outer rotor type motor and other devices.

The motor housing comprises a cylindrical portion 11a and a lid portion 11b. Bearing 12a on the end surface of the cylindrical portion 11a
The output shaft 5 is supported by the bearing 12b of the lid portion 11b. The output shaft 5 has a fixing member (flange portion) 4 on which the end portion 3 of the barrel portion 1 of the tubular flexspline is attached.
The (fulcrum side of bending) is fixed in the cylindrical portion 11a. A gear portion 2 is formed on the outer periphery of the opening of the body portion 1 of the flexspline. A circular spline 15 having inner teeth slightly larger than the number of teeth of the gear portion 2 of the flexspline is fixed to the inner periphery of the cylindrical portion 11a at a position opposed to the gear portion 2 of the flexspline.

Next to the flexspline body 1 in the axial direction of the output shaft 5 in the cylindrical portion 11a, a rotor yoke 17 is rotatably attached to the output shaft 5 by bearings 16a and 16b. A rotor magnet 18 is fixed to the outer periphery of the rotor yoke 17, and a stator 19 is fixed inside the cylindrical portion 11a with a gap. Rotor yoke 17
Is rotated as a motor by the action of the rotating magnetic field generated by the stator 19 and the rotor magnet 18.

At the symmetrical position from the center of the rotor yoke 17, the tip extends inside the body portion 1 of the flexspline.
The two roller shafts 20a and 20b are fixed, and the rollers 21a and 21b are attached to the ends thereof. Roller 21
General-purpose ball bearings can be used for a and 21b, and the maintainability is significantly improved compared to the wave generator of FIG. 4A, resulting in a significant cost reduction. The rollers 21a and 21b are brought into contact with the body portion 1 of the flexspline so as to push the position of the gear portion 2 of the flexspline or the vicinity of the opening from the inside, and the gear portion 2 of the flexspline bends in an elliptical shape. Due to this bending, a part of the gear portion 2 of the flexspline is changed to the circular spline 1.
It meshes with the internal teeth of 5.

The operation of the thus-configured motor with a wave gear device will be described. The body 1 of the flexspline is
Since the rollers 21a and 21b are always pushed outward, they are narrowed inward by a reaction in a direction orthogonal to this direction, and the vicinity of the opening of the body portion 1 of the flexspline is bent into an elliptical shape. By flexing the body portion 1 of the flexspline into an elliptical shape, the gear portion 2 of the flexspline and the inner teeth of the circular spline 17 are formed at two locations in the major axis direction of the ellipse.
Always mesh. Here, when the rotor yoke 17 rotates once by the magnetic field generated by the stator 19, the flexspline moves in the opposite direction by the difference in the number of teeth, and the rotational output decelerated from the output shaft 5 is obtained.

In the configuration shown in FIG. 3, the flexspline can be manufactured in a small size, so that the motor itself can be manufactured in a small size. Also,
The positional accuracy of the flexspline and the rollers 21a and 21b is important, but since they can be assembled on the same axis of the output shaft 5, the positional accuracy of these is good. Since the rotor yoke 17 for fixing the roller shafts 20a and 20b can be attached by providing a span in the axial direction of the output shaft 5, the rigidity of the rollers 21a and 21b can be increased (the longer the bearing span, the higher the rigidity). , The reliability of operation is increased. Further, since the motor rotation is directly transmitted from the rotor yoke 17 to the wave generation rollers 21a and 21b, the conventional motor rotation shaft and the rotation shaft of the wave gear,
Also, the bearings and joints for them are unnecessary, the number of parts is reduced, the structure is extremely simplified, the cost is reduced, and the reliability is improved.

FIG. 4 is a sectional view of a flexspline showing an embodiment of the present invention 2. This example is characterized in that the output shaft and the flexspline are machined and formed from one rod-shaped member as an integral structure. Rod-shaped member (solid material)
As the material of the above, for example, a mechanical structural alloy such as Ni (nickel) Cr (chromium) Mo (molybdenum) steel defined by JIS as SNCM can be used.

First, the gear portion 2 is processed and formed on a rod-shaped member. Next, the outside of the body portion 1 of the flexspline is processed and formed. Next, the gear portion 2 is controlled by restricting outward deformation.
And the inside of the flexspline of the body portion 1 and the diaphragm portion 7 are thinly processed and formed to have flexibility,
The inner output shaft 5a is processed and formed. Finally, the outer side of the diaphragm portion 7 and the output shaft 5b connected to the outer side are processed and formed. It should be noted that this processing method is an example, and for example, the outside of the diaphragm portion 7 and the output shaft 5b connected to it are connected to the outside.
The processing and forming may be performed after the processing and forming on the outside of the body portion 1 of the flexspline. Further, at the time of processing, a curved (R) or flat (C) taper portion is provided at the joint between one or both of the output shafts 5a and 5b and the diaphragm portion 7, so that the stress to the joint is increased. It is preferable for avoiding concentration.

In this way, if the flexspline and the output shaft are made into an integral structure by processing from one rod-shaped member, the flange portion as the fastening portion is eliminated, the structure is simplified, and downsizing can be accommodated. Further, the coaxiality between the output shaft and the gear portion is improved, the manufacture is facilitated, and the performance and reliability as the gear are improved.

[0032]

As is apparent from the above, according to the present invention 1, the conventional cup-shaped flexspline structure is complicated and large, and the flange portion and the diaphragm portion, which are large in size, are eliminated, and the tubular elastic body is fixed. Since it has a simple structure that it is fixed to the member, it is easy to manufacture and the cost can be reduced.
It is possible to obtain high reliability and to make it suitable for miniaturization.

Further, according to the second aspect of the present invention, the flange portion which complicates and enlarges the shape and structure of an ordinary cup-shaped flexspline is eliminated, and the flexspline and the output shaft are machined and formed from one rod-shaped member. Since it has a simple structure, it can be easily manufactured, cost can be reduced, high reliability can be obtained, and miniaturization can be achieved.

[Brief description of drawings]

FIG. 1 is a sectional view of a flexspline showing an embodiment of the present invention 1. FIG.

FIG. 2 is a sectional view of a flexspline showing another embodiment example of the present invention 1.

3 (a) and 3 (b) are configuration diagrams of a motor using the wave gear device of the first invention.

FIG. 4 is a sectional view of a flexspline showing an embodiment of the present invention 2.

5A is a configuration diagram of a conventional wave gear device, and FIG.
Is a sectional view of the flexspline

[Explanation of symbols]

1 ... Body 2 ... Gear 3 ... edge 4 ... Fixing member 5, 5a, 5b ... Output shaft 6 ... Ring-shaped member 7 ... Diaphragm part

Claims (6)

[Claims] 1. A wave gear device having a flexspline and a circular spline, wherein a gear part that meshes with the circular spline is formed in one of the openings of the tubular elastic body, and the other part is fixed to a fixing member. A wave gear device characterized in that 2. The wave gear device according to claim 1, wherein the fixing member has an integral structure with the output shaft. 3. The flexspline deformation, wherein the end portion of the tubular elastic body that is in contact with the fixing member is made thicker, and one or both of the end portion and the outer side is gradually made thinner toward the gear portion, 3. A curved or flat taper portion for avoiding the concentrated stress of the above is provided.
The wave gear device according to. 4. A curved or flat taper portion is provided on one or both of the inner and outer edges of the fixing member in contact with the tubular elastic body to avoid concentrated stress during flexspline deformation. The wave gear device according to claim 1 or 2, characterized in that. 5. A wave gear device having a flexspline and a circular spline, wherein the output shaft and the flexspline are integrally formed from one rod-shaped member. 6. The wave gear device according to claim 1, wherein the gear portion is first formed, and then the outer side of the flexspline body is formed, and then the outward deformation of the body is restricted so that the inner side of the flexspline and the output are formed. The wave gear device according to claim 5, wherein the wave gear device is formed with a shaft.