JP7429023B2 - Wave gear device - Google Patents

Description

The present invention relates to a wave gear device.

For example, in a robot whose arms move via joints, the rotation of a motor built into a given arm is decelerated by a reducer, and the decelerated output drives an arm connected to that arm to rotate. ing. As this type of speed reducer, one using a wave gear device is known.

Patent Document 1 describes an annular circular spline (rigid internal gear), a thin cup-shaped flexspline (flexible external gear) located on the inner peripheral side, and a circular spline (flexible external gear) fitted on the inner peripheral side. A wave gear device is disclosed that includes a wave generator having an elliptical cam. The flex spline is bent into an elliptical shape by the cam of the wave generator and is partially meshed with the circular spline. When the cam of the wave generator rotates in response to rotation input from a motor, etc., the meshing position of both gears moves in the circumferential direction, and a relative rotational movement is created between the two gears according to the difference in the number of teeth between the two gears. Occur. The wave gear device according to Patent Document 1 is configured to obtain a deceleration rotational output from a flexspline, and specifically has a structure in which an output shaft is attached to a diaphragm that forms the bottom of the flexspline.

JP2012-72912A

First, the wave gear device according to Patent Document 1 has a problem in that the flex spline is easily damaged due to its structure. This is due to the following reason. Here, consider a plurality of virtual points arranged in the circumferential direction around the rotation axis (hereinafter referred to as the axis) of the output shaft as points for transmitting force from the rotating flexspline to the output shaft. Due to the flexibility of the rotating flexspline and the elliptical shape of the cam, the vector of force applied to each virtual point from the rotating flexspline does not point uniformly in the circumferential direction, and the phase varies depending on the point. A shift occurs. Here, the flexspline according to Patent Document 1 has a structure in which the output shaft is fixed to a diaphragm that closes one end of the cylindrical portion, so that rotational force is transmitted to the output shaft over the entire circumference of the cylindrical portion. , the state includes many force vectors that have phase shifts as described above. This generates unnecessary stress in the cylindrical portion of the flexspline that does not contribute to the torque for rotating the output shaft about the rotation axis, and unnecessary twisting force is applied. In addition to this unnecessary twisting force being applied, flexsplines have the problem of being easily damaged because their cylindrical portions are formed with very thin walls (for example, the wall thickness is about 0.1 mm). be.

In addition, the flexspline according to Patent Document 1 has a structure in which the output shaft is fixed to a diaphragm that closes one end of the cylindrical part, so that the position of the output shaft is changed by the height of the cylindrical part (length along the axis). It moves away from the rotating body on the side (for example, the cam of a wave generator). For this reason, there is also the problem that the wave gear device tends to become larger in the direction along the axis.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wave gear device that is less likely to be damaged and can suppress the increase in size of the device.

In order to achieve the above object, the strain wave gear device according to the present invention includes:
an internal gear portion having an inner gear formed along the inner peripheral surface;
a wave generating section having a cam section that rotates around an axis in response to a rotational input;
A flex having a ring-shaped outer gear formed along an outer peripheral surface with a smaller number of teeth than the inner gear, the inner peripheral side of which is fitted into the wave generation part, and an adjacent part adjacent to the outer gear in a direction along the axis. The gear part and
an output shaft portion having a facing portion that faces the adjacent portion in a radial direction centered on the axis, and rotating with respect to the internal gear portion together with the flex gear portion;
a fixing part that fixes the flex gear part to the output shaft part by partially fixing the adjacent part to the opposing part in a circumferential direction centering on the axis;
The cam portion has N (N is an integer of 2 or more) pole portions located at equal intervals in the circumferential direction, and engages the outer gear with the inner gear at N locations,
There are multiple fixing parts,
N pole-corresponding fixing parts arranged at equal intervals in the circumferential direction,
It is not provided at an intermediate position between the pole-corresponding fixing parts that are adjacent to each other in the circumferential direction.

According to the present invention, it is difficult to break and it is possible to suppress the increase in size of the device.

1 is an external view of a robot in which a wave gear device according to a first embodiment of the present invention is incorporated. FIG. 1 is a configuration diagram including a schematic cross section of the main components of the wave gear device according to the first embodiment. FIG. 2 is a diagram of the main components of the strain wave gear device according to the first embodiment, viewed from the axial direction. (a) to (d) are principle diagrams for explaining the operation of the wave gear device according to the first embodiment. (a) is a schematic sectional view of the main components of the wave gear device according to the first embodiment, and (b) is a schematic sectional view of the main components of the wave gear device according to the conventional example. FIG. 6 is a diagram showing a modification of the first embodiment, in which (a) shows a case where the number of poles of the cam part is 3, and (b) shows a case where the number of poles of the cam part is 4. be. FIG. 6 is a diagram showing a modification of the first embodiment, in which (a) shows a case where the number of poles of the cam part is 5, and (b) shows a case where the number of poles of the cam part is 6. be. FIG. 6 is a diagram showing a modification of the first embodiment, in which (a) shows a case where the number of poles of the cam part is 7, and (b) shows a case where the number of poles of the cam part is 8. be. FIG. 6 is a diagram showing the main configuration of a wave gear device according to a second embodiment, in which (a) shows a case where the number of poles of the cam part is 2, and (b) shows a case where the number of poles of the cam part is 3. It is a figure showing a case.

An embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
The strain wave gear device 100 according to this embodiment is incorporated into an industrial robot 200, as shown in FIG. The robot 200 is, for example, a vertically articulated robot, and includes a robot main body 210 installed on a base 201 and a controller 220 that drives and controls the robot main body 210. The robot main body 210 includes a first arm 211, a second arm 212 connected to the first arm 211 via the wave gear device 100, and a motor 213 shown in FIG. The motor 213 is composed of a servo motor or the like, and operates under the control of the controller 220. The controller 220 controls the positioning and angle of the second arm 212 relative to the first arm 211 by rotationally driving the second arm 212 via the motor 213 built into the first arm 211 and the wave gear device 100. and rotation speed control.

As shown in FIG. 2, the wave gear device 100 includes a wave generation section 10, a flex gear section 20, an internal gear section 30, an output shaft section 40, a support section 50, and a fixed section 60.

Note that in FIG. 2, hatching showing cross sections of some components is omitted for ease of viewing, and the first arm 211 and the second arm 212 are shown with imaginary lines. Furthermore, hereinafter, when describing the configuration of the wave gear device 100, the right side in FIG. 2 may be referred to as an input side (Si in the drawing), and the left side may be referred to as an output side (So in the drawing). The same applies to FIG. 5, which will be described later.

The wave generating section 10 includes a cylindrical shaft section 11 , a cam section 12 formed integrally with the cylindrical shaft section 11 , and a wave bearing 13 .

The cylindrical shaft portion 11 has an input side end rotatably supported by a bearing B1, and an output side end rotatably supported by a bearing B2. The bearing B1 is provided on a stationary portion 211a that is stationary with respect to the first arm 211. The bearing B2 is provided on the inner peripheral surface of the output shaft portion 40. The bearings B1 and B2 are composed of, for example, ball bearings. Thereby, the cylindrical shaft portion 11 is rotatably supported by the first arm 211 around the axis AX. The rotational power of the motor 213 is transmitted to the cylindrical shaft portion 11 via a known transmission mechanism. This transmission mechanism may be a gear mechanism, a belt mechanism using a timing belt and a pulley, or the like.

The cam portion 12 is provided to protrude from the outer peripheral surface of the cylindrical shaft portion 11 in the outer radial direction. The cam portion 12 is provided at a position adjacent to the bearing B1 in the direction along the axis AX (hereinafter referred to as the axial direction). The cam portion 12 has N (N is an integer of 2 or more) pole portions located at equal intervals in the circumferential direction around the axis AX.

Hereinafter, the number of poles that the cam portion 12 has will be referred to as the number of poles, and in this embodiment, a case where the number of poles is N=2 will be described. When N=2, the cam portion 12 has an elliptical shape when viewed from the axial direction, as shown in FIG. FIG. 2 shows a schematic cross section when the number of poles of the cam portion 12 is N=2.

The wave bearing 13 includes an inner ring 13i fixed to the outer peripheral surface of the cam part 12, a flexible outer ring 13o, and a plurality of balls 13b inserted in a rotatable state between the inner ring 13i and the outer ring 13o. have Note that the inner ring 13i may be configured from a portion including the outer circumferential surface of the cam portion 12.

The flex gear section 20 is made of a flexible metal material such as special steel, and includes an outer gear 21 and an adjacent section 22 formed integrally with the outer gear 21.

The outer gear 21 is formed into a ring shape with a predetermined number t of teeth 21a formed along the outer circumferential surface, and the inner circumferential side is fitted into the outer ring 13o of the wave generating section 10. The plurality of teeth 21a in the outer gear 21 are arranged along the circumferential direction at a constant pitch. The number t of teeth of the outer gear 21 is set to be smaller than the number T of teeth of the inner gear 31, which will be described later. For example, when the number of poles of the cam portion 12 is N, the relationship between the number of teeth t and the number of teeth T is set so that "T=t+N" holds true. Therefore, when N=2, the relationship "T=t+2" holds true.

The adjacent portion 22 is a portion adjacent to the outer gear 21 in the axial direction and protrudes from the outer gear 21 toward the output side. A through hole 22a is formed in the adjacent portion 22 and extends in a direction substantially perpendicular to the axis AX (including a direction exactly perpendicular to the axis AX). A fixing pin F, which will be described later and which constitutes the fixing part 60, is inserted into the through hole 22a.

Although not shown, a portion recessed toward the outer circumferential side is provided on the inner circumferential surface of the flex gear portion 20 at a position corresponding to between adjacent teeth among the plurality of teeth 21a formed on the outer gear 21, The flex gear portion 20 may be made easily flexible.

The internal gear part 30 is a part that is rigidly formed of a metal material, is fixed inside the first arm 211, and is partially connected to the outer gear 21 of the flex gear part 20 bent by the cam part 12. It has an inner gear 31 that meshes with it.

The inner gear 31 is formed into a ring shape with a predetermined number of teeth T (T>t) of teeth 31a formed along the inner peripheral surface. The plurality of teeth 31a in the inner gear 31 are arranged along the circumferential direction at a constant pitch.

The output shaft section 40 rotates with respect to the internal gear section 30 together with the flex gear section 20. The output shaft section 40 is supported by a support section 50 so as to be rotatable about the axis AX with respect to the internal gear section 30. The output shaft portion 40 is made of, for example, a metal material and has rigidity and is formed into a ring shape. The output shaft portion 40 includes an opposing portion 41 that faces the adjacent portion 22 of the flex gear portion 20 in a radial direction centered on the axis AX, and a portion located on the output side of the opposing portion 41 and supported by the support portion 50. It has a supported part 42 which is .

The support part 50 is made of, for example, a cross roller bearing, and has an outer ring 51 fixed to the internal gear part 30 and an inner ring 52 fixed to the supported part 42 of the output shaft part 40. Thereby, the support part 50 supports the output shaft part 40 rotatably around the axis AX with respect to the internal gear part 30.

In this embodiment, the output shaft portion 40 is connected to the second arm 212, which is a load of the wave gear device 100, via the inner ring 52 of the support portion 50. Thereby, as the output shaft portion 40 rotates, the second arm 212 rotates around the axis AX. Note that the manner in which the output shaft portion 40 is supported by the support portion 50 is arbitrary, and for example, the inner circumferential surface of the inner ring 52 of the support portion 50 may be fixed to the output shaft portion 40. Furthermore, the connection method between the output shaft section 40 and the load (in this example, the second arm 212) may be arbitrary. For example, the load may be connected to a disk-shaped plate fixed to the output shaft section 40. You can.

As shown in FIG. 2, the adjacent portion 22 of the flex gear portion 20 and the opposing portion 41 of the output shaft portion 40 are located between the support portion 50 and the cam portion 12 in the axial direction. By fixing the adjacent portion 22 to the opposing portion 41 by the fixing portion 60, the output shaft portion 40 rotates together with the flex gear portion 20.

The fixing portion 60 includes, for example, a fixing pin F inserted into a guide bush 41a embedded in the opposing portion 41 of the output shaft portion 40. The fixing pin F is fixed in the guide bush 41a through a through hole 22a provided in the adjacent portion 22 of the flex gear portion 20 by a fixing method such as screwing, fitting, fixing, welding, or the like. The fixing pin F fixes the adjacent portion 22 of the flex gear portion 20 to the opposing portion 41 of the output portion 40 from the outer circumferential side toward the inner circumferential side. It is preferable that the fixing pin F extends in a radial direction centered on the axis AX.

As shown in FIG. 3, in this embodiment in which the number of poles of the cam portion 12 is N=2, two fixing portions 60 are provided corresponding to this number of poles. The two fixing parts 60 are spaced apart from each other by 180 degrees in rotation angle around the axis AX. That is, the two fixing parts 60 are arranged at equal intervals in the circumferential direction centered on the axis AX. In this embodiment, one fixing portion 60 is composed of one fixing pin F.

In FIG. 3, the adjacent portion 22 of the flex gear 20 is partially shown. Note that the shape of the adjacent portion 22 protruding toward the output side relative to the outer gear 21 is arbitrary, and may be protruding in a ring shape, or only the portion corresponding to the fixed portion 60 may protrude toward the output side relative to the outer gear 21. You can leave it out.

(motion)
Next, the operation of the strain wave gear device 100 having the above configuration will be described mainly in accordance with FIGS. 4(a) to 4(d) while referring to FIGS. 1 to 3.

When the motor 213 operates under the control of the controller 220 of the robot 200, the rotational power of the motor 213 is transmitted to the cam section 12 of the wave generation section 10 via a transmission mechanism (not shown), and the cam section 12 is moved relatively around the axis AX. Rotate at high speed.

Here, in order to make the explanation easier to understand, the cam part 12 before the start of rotation is initially set such that the long axis of the elliptical shape coincides with the axis passing through 0° and 180°, as shown in FIG. 4(a). Assume that it is at position Cs. Note that the illustrated angle is a rotation angle around the axis AX, and assumes that the 12 o'clock direction is 0° and the angle increases in a clockwise direction. Further, it is assumed that the cam portion 12 rotates clockwise.

As shown in FIG. 4(a), the cam part 12 at the initial position Cs is engaged with the flex gear part 20 (specifically In this case, the outer gear 21 (not shown in FIG. 4) is meshed with the internal gear part 30 (specifically, the inner gear 31 (not shown in FIG. 4)). In this state, it is assumed that the fixed point Xo of the internal gear section 30 is set at the 0 degree position, and the reference point Xf of the flex gear section 20 is also at the 0 degree position.

FIG. 4(b) shows a state in which the cam portion 12 is rotated by 90 degrees from the initial position Cs and is at a position C1 where the major axis direction coincides with an axis passing through 90 degrees and 270 degrees.
When the cam portion 12 is displaced from the initial position Cs to the position C1, the meshing positions E and E of the flex gear portion 20 and the internal gear portion 30 move to positions of 90° and 270°. At this time, the number of teeth of the outer gear 21 is t, the number of teeth of the inner gear 31 is T=t+2, and the difference in the number of teeth is T-t=2, so the reference point Xf of the flex gear section 20 is the fixed point It rotates counterclockwise with respect to Xo by 1/2 tooth, which is 1/4 (=90°/360°) of the difference in the number of teeth "2". Letting this counterclockwise rotation angle be θ1, it is expressed as θ1={(360°/T)×2}/4.

FIG. 4(c) shows a state in which the cam portion 12 has rotated 180° from the initial position Cs and is at a position C2 where the major axis direction coincides with an axis passing through 180° and 0°.
When the cam portion 12 is displaced from the initial position Cs to the position C2, the meshing positions E and E of the flex gear portion 20 and the internal gear portion 30 move to the 180° and 0° positions. At this time, the reference point Xf of the flex gear section 20 is rotated counterclockwise by one tooth, which is 1/2 of the difference in the number of teeth "2" (=180°/360°), with respect to the fixed point Xo. do. Letting this counterclockwise rotation angle be θ2, it is expressed as θ2={(360°/T)×2}/2.

FIG. 4(d) shows a state in which the cam portion 12 has rotated 360° from the initial position Cs and is at a position C3 where the major axis direction coincides with an axis passing through 0° and 180°.
When the cam portion 12 is displaced from the initial position Cs to the position C3 (that is, rotated 360°), the meshing positions E, E of the flex gear portion 20 and the internal gear portion 30 return to the 0° and 180° positions. At this time, the reference point Xf of the flex gear section 20 rotates counterclockwise with respect to the fixed point Xo by the difference in the number of teeth "2". Letting this counterclockwise rotation angle be θ3, it is expressed as θ3=(360°/T)×2.

As described above, when the cam part 12 is rotated, the flex gear part 20 is elastically deformed, and the meshing positions E, E with the internal gear part 30 are sequentially moved. Then, when the cam portion 12 rotates once clockwise, the flex gear portion 20 moves counterclockwise by the number of teeth 2 (=Tt). As a result, the output shaft portion 40 fixed to the flex gear portion 20 by the fixing portion 60 is reduced in speed with respect to the rotational speed of the cam portion 12 by the reduction ratio i=(T−t)/t. In other words, according to the wave gear device 100, the rotation of the load (in this example, the second arm 212) connected to the output shaft portion 40 can be controlled with high precision using an output that is decelerated by the above-mentioned reduction ratio i. can. Note that the reduction ratio i is arbitrary, but is set to about 1/30 to 1/320, for example.

As described above, when the cam part 12 of the wave generation part 10 rotates in response to the rotation input from the motor 213, the meshing positions E, E of both gears of the flex gear part 20 and the internal gear part 30 move in the circumferential direction. At the same time, the flex gear section 20 rotates in the opposite direction to the cam section 12 with respect to the internal gear section 30 according to the difference in the number of teeth between the two gears. At this time, force is transmitted from the flex gear section 20 to the output shaft section 40 by two fixing sections 60 corresponding to the number of poles (N=2).

Here, in order to make the explanation easier to understand, first of all, the positions P and P where the fixing part 60 shown in FIG. 3 is provided are the position of the reference point Xf of the flex gear part 20 shown in FIG. , it is assumed that the position is moved 180° from this position. Then, since the state of the flex gear section 20 with respect to the internal gear section 30 is the same at each of the two positions P and P, the rotating flex gear section 20 is connected to the output shaft section 40 via the fixed section 60. It can be seen that, in principle, the phase shift described in the above problem does not occur in the vector of the transmitted force.
In reality, since the flex gear section 20 performs rotational movement with respect to the internal gear section 30, the positions P, P where the fixing section 60 is provided do not remain in the state shown in FIG. 3. However, regardless of the rotational position of the flex gear section 20, since the state of the flex gear section 20 with respect to the internal gear section 30 is the same at each of the two positions P, P, the flex gear section 20 rotates. Similarly, in the vector of force transmitted from the flex gear section 20 to the output shaft section 40 via the fixed section 60, the phase shift described in the above-mentioned problem does not occur in principle.

In other words, with the fixing parts 60 provided at the positions P and P according to this embodiment, unnecessary stress that does not contribute to the torque for rotating the output shaft part 40 around the axis AX is applied to the flex gear part 20 and the output shaft. The occurrence of unnecessary torsional force on each of the sections 40 is reduced, and the unnecessary torsional force applied to the flex gear section 20 is reduced. As a result, according to the wave gear device 100 of this embodiment, mechanical loss due to the connection between the flex gear section 20 and the output shaft section 40 can be significantly reduced, and good transmission efficiency can be achieved. Furthermore, damage to the flex gear portion 20 can be suppressed.

Furthermore, since the output points (that is, positions P, P) for transmitting force from the flex gear section 20 to the output shaft section 40 can be uniformly distributed in the circumferential direction, the meshing points E between the flex gear section 20 and the internal gear section 30, The load per point E is reduced, and as a result, the output shaft portion 40 can be rotated with high torque.

Furthermore, the advantages of the wave gear device 100 according to this embodiment will be explained by comparing FIG. 5(a) and FIG. 5(b). FIG. 5(a) is a diagram of the strain wave gear device 100 according to the present embodiment extracted from FIG. It is a figure showing 100p.

In the wave gear device 100p according to the conventional example, configurations corresponding to the respective configurations of the wave gear device 100 according to the present embodiment are illustrated with “p” added to the end of the reference numeral. To explain the main correspondence between the conventional example and this embodiment, the wave generator 10p corresponds to the wave generation section 10, the flex spline 20p corresponds to the flex gear section 20, and the circular spline 30p corresponds to the internal gear section 30. .

As shown in FIG. 5(b), in the conventional flexspline 20p, the output shaft 40p is fixed by a fixing member 60p to a diaphragm that closes the output end of the cylindrical portion. The position of the output shaft 40p moves away from the rotating body on the input side (for example, the cam of the wave generator 10p) by a length Lp corresponding to the height.

On the other hand, as shown in FIG. 5(a), the wave gear device 100 according to the present embodiment has a structure in which force is transmitted from the adjacent portion 22 of the flex gear portion 20 to the output shaft portion 40 via the fixed portion 60. At the same time, the adjacent portion 22 of the flex gear portion 20 and the opposing portion 41 of the output shaft portion 40 are located between the support portion 50 and the cam portion 12. As a result, the length from the cam part 12 to the output point of the flex gear part 20 (that is, the position of the fixed part 60 that transmits force from the flex gear part 20 to the output shaft part 40) can be set to L, and as a result, In addition, each component can be made compact in the axial direction, and the strain wave gear device 100 can be configured in a small size.

In addition, in the wave gear device 100 according to the present embodiment, the flex gear portion 20 has a bottomless cylindrical shape (ring shape when viewed from the axial direction), and the output side end portion is shaped like the flex spline 20p according to the conventional example. Since it is not closed by a diaphragm, the flexibility of the flex gear part 20 can be maintained while ensuring a certain degree of wall thickness of the flex gear part 20. Therefore, the flex gear portion 20 can have good resistance to buckling and is less likely to be damaged. Note that the thickness of the flex gear portion 20 is not limited, but can be set to about 0.5 mm to 1 mm, for example. Further, the flex gear portion 20 has a bottomless cylindrical shape and is easier to process than a bottomed cylindrical one like the conventional flex spline 20p.

In addition, in the conventional example, the cylindrical portion of the flex spline 20p needs to have a certain length in the axial direction due to its structure, and the support portion 50p that supports the output shaft 40p is located from the meshing position of the flex spline 20p and the circular spline 30p. Go away. In such a conventional structure, stress in a direction oblique to the axis AX is likely to be applied to both the flex spline 20p and the circular spline 30p, and both gears are likely to wear out.
On the other hand, in the wave gear device 100 according to the present embodiment, the adjacent portion 22 of the flex gear portion 20 and the opposing portion 41 of the output shaft portion 40 are located between the support portion 50 and the cam portion 12, so that they are mutually connected to each other. Stress in a direction oblique to the axis AX is less likely to be applied to the flex gear part 20 and the internal gear part 30 that mesh with each other. As a result, one tooth ridge and the other tooth bottom of the flex gear section 20 and the internal gear section 30 can be brought into contact along the axial direction, and wear of each gear can be suppressed.

In addition, in the wave gear device 100 according to the present embodiment, not only the cam portion 12 but also the flex gear portion 20 and the output shaft portion 40 are hollow and ring-shaped when viewed from the axial direction, so that wiring etc. can be passed through. Space can be secured inside. In addition, according to the strain wave gearing device 100 according to the present embodiment, it goes without saying that backlash can be eliminated in principle and lost motion can be minimized.

(Modified example of the first embodiment)
In the above description, a case has been described in which the cam portion 12 is elliptical and the number of poles is N=2, but the number of poles is arbitrary as long as it is an integer of 2 or more. From here on, the case where the number of poles is N≧3 will be explained with reference mainly to FIGS. 6 to 8.

When the number of poles is N≧3, as shown in FIGS. 6 to 8, the shape of the cam portion 12 when viewed from the axial direction is a regular N-gon shape, and, for example, each pole portion and the adjacent pole It has a curved surface shape in which the space between the parts gently bulges in the outer circumferential direction.
The outer gear 21 of the flex gear portion 20 is bent by the cam portion 12 having N pole portions via a wave bearing 13, and meshes with the inner gear 31 of the internal gear portion 30 at N locations. When the number of poles of the cam part 12 is N, the number of teeth t of the outer gear 21 (hereinafter also referred to as the number t of teeth of the flex gear part 20) and the number T of teeth of the inner gear 31 (hereinafter also referred to as the number T of teeth of the internal gear 30) ) is set so that "T=t+N" holds true.
For example, when the cam portion 12 rotates 360° clockwise, the flex gear portion 20 moves counterclockwise by N teeth. That is, when the number of poles of the cam part 12 is N, when the cam part 12 rotates through an angle of (360°/N), the flex gear part 20 moves by one tooth with respect to the internal gear part 30. When the number of poles of the cam part 12 is N, the output shaft part 40 fixed to the flex gear part 20 has a reduction ratio i=(T-t)/t=N/t with respect to the rotational speed of the cam part 12. is decelerated.

Further, when the number of poles is N≧3, the fixing portions 60 made of fixing pins F are provided at N positions P arranged at equal intervals in the circumferential direction centered on the axis AX. Note that in FIGS. 6 to 8, the fixing part 60 is not shown in consideration of the ease of viewing the drawings, but the position P where the fixing part 60 is provided is shown. In addition, also in the following modification of the first embodiment, it is assumed that one fixing portion 60 is composed of one fixing pin F. Further, FIGS. 6 to 8 show a state in which any one of the N pole parts of the cam portion 12 is at the 0° position. This also applies to FIG. 9, which will be referred to in the second embodiment described later. Hereinafter, the case where the number of poles is N≧3 will be explained in order.

(If N=3)
As shown in FIG. 6(a), when the number of poles of the cam part 12 is N=3, the flex gear part 20 is bent by the cam part 12 having three pole parts, and the internal gear part It meshes with 30. The relationship between the number t of teeth of the flex gear section 20 and the number T of teeth of the internal gear 30 is "T=t+3". In this case, when the cam portion 12 rotates 360° clockwise, the flex gear portion 20 moves counterclockwise by three teeth. That is, when the cam part 12 rotates through an angle of (360°/3), the flex gear part 20 moves by one tooth relative to the internal gear part 30. When N=3, the output shaft section 40 fixed to the flex gear section 20 is reduced in speed with respect to the rotational speed of the cam section 12 by a reduction ratio i=(Tt)/t=3/t.
Further, when the number of poles of the cam part 12 is N=3, the number of fixing parts 40 that fix the flex gear part 20 to the output shaft part 40 is three arranged at equal intervals in the circumferential direction centered on the axis AX. is provided at position P. The angle between adjacent positions among the three positions P is (360°/3).

(When N=4)
As shown in FIG. 6(b), when the number of poles of the cam part 12 is N=4, the flex gear part 20 is bent by the cam part 12 having four pole parts, and the internal gear part It meshes with 30. The relationship between the number of teeth t of the flex gear section 20 and the number T of teeth of the internal gear 30 is "T=t+4". In this case, when the cam portion 12 rotates 360° clockwise, the flex gear portion 20 moves counterclockwise by four teeth. That is, when the cam part 12 rotates through an angle of (360°/4), the flex gear part 20 moves by one tooth relative to the internal gear part 30. When N=4, the output shaft section 40 fixed to the flex gear section 20 is reduced in speed with respect to the rotational speed of the cam section 12 by a reduction ratio i=(Tt)/t=4/t.
Further, when the number of poles of the cam part 12 is N=4, the number of fixing parts 40 that fix the flex gear part 20 to the output shaft part 40 is four arranged at equal intervals in the circumferential direction centered on the axis AX. is provided at position P. The angle between adjacent positions among the four positions P is (360°/4).

(If N=5)
As shown in FIG. 7(a), when the number of poles of the cam part 12 is N=5, the flex gear part 20 is bent by the cam part 12 having five pole parts, and there are internal gear parts at five places. It meshes with 30. The relationship between the number t of teeth of the flex gear section 20 and the number T of teeth of the internal gear 30 is "T=t+5". In this case, when the cam portion 12 rotates 360° clockwise, the flex gear portion 20 moves counterclockwise by five teeth. That is, when the cam part 12 rotates through an angle of (360°/5), the flex gear part 20 moves by one tooth relative to the internal gear part 30. In the case of N=5, the output shaft portion 40 fixed to the flex gear portion 20 is reduced in speed with respect to the rotational speed of the cam portion 12 by a reduction ratio i=(T−t)/t=5/t.
Further, when the number of poles of the cam part 12 is N=5, the number of fixing parts 40 that fix the flex gear part 20 to the output shaft part 40 is five, arranged at equal intervals in the circumferential direction centered on the axis AX. is provided at position P. The angle between adjacent positions among the five positions P is (360°/5).

(When N=6)
As shown in FIG. 7(b), when the number of poles of the cam part 12 is N=6, the flex gear part 20 is bent by the cam part 12 having six pole parts, and the internal gear part It meshes with 30. The relationship between the number t of teeth of the flex gear section 20 and the number T of teeth of the internal gear 30 is "T=t+6". In this case, when the cam portion 12 rotates 360° clockwise, the flex gear portion 20 moves counterclockwise by six teeth. In other words, when the cam portion 12 rotates through an angle of (360°/6), the flex gear portion 20 moves by one tooth relative to the internal gear portion 30. In the case of N=6, the output shaft section 40 fixed to the flex gear section 20 is reduced in speed with respect to the rotational speed of the cam section 12 by a reduction ratio i=(Tt)/t=6/t.
Further, when the number of poles of the cam part 12 is N=6, there are six fixing parts 40 that fix the flex gear part 20 to the output shaft part 40, arranged at equal intervals in the circumferential direction centering on the axis AX. is provided at position P. The angle between adjacent positions among the six positions P is (360°/6).

(If N=7)
As shown in FIG. 8(a), when the number of poles of the cam part 12 is N=7, the flex gear part 20 is bent by the cam part 12 having seven pole parts, and the internal gear part It meshes with 30. The relationship between the number of teeth t of the flex gear section 20 and the number T of teeth of the internal gear 30 is "T=t+7". In this case, when the cam part 12 rotates 360 degrees clockwise, the flex gear part 20 moves counterclockwise by seven teeth. That is, when the cam part 12 rotates through an angle of (360°/7), the flex gear part 20 moves by one tooth relative to the internal gear part 30. When N=7, the output shaft section 40 fixed to the flex gear section 20 is reduced in speed with respect to the rotational speed of the cam section 12 by a reduction ratio i=(T-t)/t=7/t.
Further, when the number of poles of the cam part 12 is N=7, there are seven fixing parts 40 that fix the flex gear part 20 to the output shaft part 40, which are arranged at equal intervals in the circumferential direction centering on the axis AX. is provided at position P. The angle between adjacent positions among the seven positions P is (360°/7).

(When N=8)
As shown in FIG. 8(b), when the number of poles of the cam part 12 is N=8, the flex gear part 20 is bent by the cam part 12 having eight pole parts, and the internal gear part It meshes with 30. The relationship between the number of teeth t of the flex gear section 20 and the number T of teeth of the internal gear 30 is "T=t+8". In this case, when the cam portion 12 rotates 360° clockwise, the flex gear portion 20 moves counterclockwise by eight teeth. That is, when the cam portion 12 rotates through an angle of (360°/8), the flex gear portion 20 moves by one tooth relative to the internal gear portion 30. When N=8, the output shaft section 40 fixed to the flex gear section 20 is reduced in speed with respect to the rotational speed of the cam section 12 by a reduction ratio i=(Tt)/t=8/t.
Further, when the number of poles of the cam part 12 is N=8, there are eight fixing parts 40 that fix the flex gear part 20 to the output shaft part 40, which are arranged at equal intervals in the circumferential direction centering on the axis AX. is provided at position P. The angle between adjacent positions among the seven positions P is (360°/8).

Although not shown, the case where N≧9 can be realized in the same way. In addition, in any case where N is, as described above, the adjacent portion 22 of the flex gear portion 20 and the output shaft portion 40 are Of course, the facing portion 41 is provided.

Even in the strain wave gear device 100 according to various modifications (N≧3) of the first embodiment described above, various effects can be obtained in the same manner as described in the case of N=2. In order to fix the flex gear 20 to the output shaft part 40 by the fixing part 60 at each of the N positions P evenly arranged in the circumferential direction, the output shaft part 40 is fixed around the axis AX in the same way as described above. The occurrence of unnecessary stress that does not contribute to the torque for rotation in each of the flex gear section 20 and the output shaft section 40 is reduced, and the application of unnecessary torsional force to the flex gear section 20 is reduced. As a result, various effects such as realizing good transmission efficiency and suppressing damage to the flex gear section 20 can be obtained.

Here, consider a case where the cam of the wave generator 10p is set in an elliptical shape, as in the wave gear device 100p according to the conventional example (the reference numerals in the conventional example are based on FIG. 5(b)). If the number of teeth of the circular spline 30p is T, the pitch circle diameter is D, the number of teeth of the flex spline 20p is t, and the pitch circle diameter is d, then the reduction ratio i is "i=(T-t)/t= 2/t" or "i=(D-d)/d". Then, in order to reduce the value of the reduction ratio i (obtain a more decelerated rotational output), it is necessary to increase the number of teeth t or increase the ratio of the diameter d of the flex spline 20p to the diameter D of the circular spline 30p. . On the other hand, in order to increase the value of the reduction ratio i (to suppress the degree of deceleration of the rotational output), it is necessary to reduce the number of teeth t, or to reduce the ratio of the diameter d of the flex spline 20p to the diameter D of the circular spline 30p. . As described above, relying only on the elliptical cam as in the conventional example results in various restrictions on the size and conditions of the device, making it difficult to realize any reduction ratio.

On the other hand, according to the variation in which the number of poles of the cam part 12 is N≧3, which was explained in the various modifications of the first embodiment, if the number of teeth T of the internal gear part 30 and the number of teeth of the flex gear part 20 are Even if at least one of t and t is kept constant, as can be seen from the reduction ratio i=N/t, it is possible to increase the value of the reduction ratio (suppress the degree of deceleration of the rotational output) just by increasing the number of poles. By simply reducing the number of poles, it is possible to reduce the value of the reduction ratio (obtain a more decelerated rotational output). In addition to variations in the number of poles, by changing the settings of the number of teeth T and the number of teeth t, and the diameter of the flex gear section 20 and internal gear section 30, it is possible to realize an almost infinite variety of reduction ratios. can.

Note that, in the above description, N fixing parts 60 (an example of pole-compatible fixing parts) are provided in correspondence with the number of poles of the cam part 12, but the number of the fixing parts 60 may be less than N. For example, when the number of poles is N, the fixing portions 60 may be provided at two or more and N or less locations arranged at equal intervals in the circumferential direction centered on the axis AX. Even in this case, unnecessary stress and twisting force as described above can be suppressed from being applied to the flex gear section 20 and the output shaft section 40. In this case, especially when the number of poles is an even number, it is considered preferable to provide the fixing portions 60 by a divisor of 2 or more among the divisors of the number of poles. For example, as shown in FIG. 7(b), in the case of N=6, the fixed part 60 is placed in a circle at "2" or "3" among the divisors of 6, that is, at two or three positions P. They may be arranged evenly in the circumferential direction. By doing this, when any pole part of the cam part 12 is located at one of the plurality of positions P evenly arranged in the circumferential direction, the pole part of the cam part 12 is also located at other positions P. will be located. As a result, the output points (positions P) for transmitting force from the flex gear section 20 to the output shaft section 40 can be evenly distributed in the circumferential direction, so that the output shaft section 40 can be rotated with high torque.

As described above, it is preferable that the number of fixing parts 60 (an example of a pole-compatible fixing part) provided corresponding to the cam part 12 having N poles is 2 or more and N or less. However, it is only necessary to fix the output shaft portion 40 partially in the circumferential direction, not over the entire circumference of the flex gear portion 20. For example, the fixing portion 60 may be fixed in the circumferential direction around the axis AX. It may be provided at any one location.

(Second embodiment)
From here on, the second embodiment will mainly be explained in which the fixing part for fixing the flex gear part 20 to the output shaft part 40 includes an auxiliary fixing part 60a in addition to the fixing part 60 as the above-mentioned pole-compatible fixing part. This will be explained with reference to 9(a) and 9(b). In the second embodiment, points different from the first embodiment will be explained.

Similarly to the above-mentioned fixing part 60, the auxiliary fixing part 60a also extends from the fixing pin F that fixes the adjacent part 22 of the flex gear part 20 to the opposing part 41 of the output part 40 from the outer circumferential side to the inner circumferential side. It is configured. The auxiliary fixing part 60a is provided at a position Q different from the position P of the fixing part 60 in the circumferential direction about the axis AX. Preferably, there are a plurality of auxiliary fixing parts 60a, and they are arranged at equal intervals in the circumferential direction.

The auxiliary fixing section 60a is particularly useful when the number of poles of the cam section 12 is relatively small (when N is 2 or 3), and contributes to the torque for rotating the output shaft section 40 around the axis AX. It is provided to increase the number of points (output points) where force is transmitted from the flex gear section 20 to the output shaft section 40 and to increase the torque.

(If N=2)
FIG. 9A shows a case where the number of poles of the cam portion 12 is N=2, and the position P of the fixing portion 60 (not shown in the figure) is the same as that in FIG. 3. In the case of N=2, in the second embodiment, in addition to the fixing parts 60 provided at two positions P, an auxiliary fixing part 60a is provided at each of four positions Q. The angle between adjacent positions among the four positions Q is set to (360°/4).

Further, in the state shown in FIG. 9(a), two positions P are at 0° and 180°, and four positions Q are at 45°, 135°, 225°, and 315°. That is, the auxiliary fixing part 60a is provided at a position that avoids the intermediate position (90°, 270°) between the neighboring fixing parts 60 in the circumferential direction. Even if the output point for transmitting from the flex gear section 20 to the output shaft section 40 is set at these intermediate positions (90°, 270°), it will not contribute much to the torque for rotating the output shaft section 40 around the axis AX. It's for a reason.

(If N=3)
FIG. 9(b) shows a case where the number of poles of the cam portion 12 is N=3, and the position P of the fixing portion 60 (not shown in the figure) is the same as that in FIG. 6(a). When N=3, in the second embodiment, in addition to the fixing parts 60 provided at the three positions P, the auxiliary fixing parts 60a are provided at each of the six positions Q. The angle between adjacent positions among the six positions Q is set to (360°/6).

In addition, in the state shown in FIG. 9(b), three positions P are at 0°, 120°, and 240°, and six positions Q are at 30°, 90°, 150°, 210°, and 270°. , at 330°. That is, the auxiliary fixing part 60a is provided at a position that avoids intermediate positions (60°, 180°, 300°) between adjacent fixing parts 60 in the circumferential direction. Even if the output point to be transmitted from the flex gear section 20 to the output shaft section 40 is set at these intermediate positions (60°, 180°, 300°), the torque for rotating the output shaft section 40 around the axis AX will not be the same. This is because it does not contribute much.

Although not shown, the auxiliary fixing portion 60a may be provided based on the same concept even in the case of N≧4. However, as described above, the auxiliary fixing section 60a is particularly useful when the number of poles of the cam section 12 is relatively small (when N is 2 or 3). Further, similarly to the fixing section 60, the adjacent section 22 of the flex gear section 20 and the opposing section 41 of the output shaft section 40 are provided corresponding to each of the plurality of positions Q (the plurality of auxiliary fixing sections 60a). Of course.

Further, the number and arrangement of the auxiliary fixing parts 60a are not limited to the examples shown in FIGS. 9(a) and 9(b), but are arbitrary. However, from the viewpoint of uniformly distributing the output points (positions Q) that transmit force from the flex gear part 20 to the output shaft part 40 in the circumferential direction and rotating the output shaft part 40 with high torque, the plurality of positions Q are Preferably, they are arranged evenly in the circumferential direction. From the same viewpoint, when the number of poles of the cam portion 12 is N, the position Q is preferably an even number multiple, such as twice N. The preferred arrangement of the auxiliary fixing part 60a is as described above, but the auxiliary fixing part 60a may be provided at the intermediate position described above, or at any one location in the circumferential direction centered on the axis AX. may be provided.

Note that the present invention is not limited to the above embodiments, modifications, and drawings. It is possible to make changes (including deletion of constituent elements) as appropriate without changing the gist of the present invention.

Although the example in which the wave gear device 100 is incorporated into the robot 200 consisting of a vertically articulated robot has been described above, the present invention is not limited to this. The strain wave gearing device 100 can be incorporated into various robots such as horizontal articulated robots and delta-type robots. Further, the device in which the wave gear device 100 is incorporated is not limited to a robot, and may be any device as long as it is used for the purpose of obtaining a rotational output that is decelerated at a desired reduction ratio in response to a rotational input.

Further, the number t of teeth of the flex gear section 20 and the number T of teeth of the internal gear section 30 are arbitrary as long as T>t. However, when the number of poles of the cam portion 12 is N, it is preferable to set the relationship between the number of teeth t and the number of teeth T as "T=t+N".

In the above example, one fixing part 60 is composed of one fixing pin F, but one fixing part 60 may be composed of a plurality of fixing pins F. For example, at any position P, one fixing portion 60 may be configured from a plurality of (for example, two) fixing pins F aligned in the axial direction. Further, at any position P, one fixing portion 60 may be configured from a plurality of (for example, two) fixing pins F arranged closely in the circumferential direction centering on the axis AX. The same applies to the auxiliary fixing part 60a, and one auxiliary fixing part 60 located at an arbitrary position Q may be composed of a plurality of fixing pins F.

Further, the fixing part 60 can be formed of a fixing pin F if the adjacent part 22 of the flex gear part 20 can be partially fixed to the opposing part 41 of the internal gear part 30 in the circumferential direction around the axis AX. It is not limited to the embodiment, but is arbitrary. For example, the fixing portion 60 may include a portion where the adjacent portion 22 and the opposing portion 41 are fitted into each other, a portion where the adjacent portion 22 and the opposing portion 41 are welded, fixed, or bonded.

(1) The wave gear device 100 described above partially connects the adjacent portion 22 of the flex gear portion 20 adjacent to the outer gear 21 to the opposing portion 41 of the output shaft portion 40 in the circumferential direction centered on the axis AX. A fixing part (for example, fixing part 60) is provided. Further, the cam portion 12 has N (N is an integer of 2 or more) pole portions located at equal intervals in the circumferential direction, and engages the outer gear 21 with the inner gear 31 at N locations.
According to this configuration, as described above, unnecessary stress mainly applied to the flex gear portion 20 can be suppressed, so that the strain wave gear device 100 is less likely to be damaged. Further, since the portion of the flex gear portion 20 that is fixed to the output shaft portion 40 is the adjacent portion 22 adjacent to the outer gear 21, it is possible to suppress the wave gear device 100 from increasing in size mainly in the axial direction. Furthermore, by arbitrarily setting the number of poles N, various reduction ratios can be realized with a simple configuration.

(2) Furthermore, there may be a plurality of fixing parts. The plurality of fixing parts include pole-compatible fixing parts (mainly corresponding to the fixing part 60 of the first embodiment) arranged at equal intervals in the circumferential direction and having a number of 2 or more and N or less.
According to this configuration, the output points for transmitting force from the flex gear section 20 to the output shaft section 40 can be uniformly distributed in the circumferential direction, so that the output shaft section 40 can be rotated with high torque.

(3) Furthermore, the plurality of fixing parts described in (2) above further include an auxiliary fixing part 60a provided at a different position from the pole corresponding fixing part (fixing part 60) in the circumferential direction.
(4) Preferably, there are a plurality of auxiliary fixing parts 60a, and they are arranged at equal intervals in the circumferential direction.
According to these configurations, it is possible to increase the locations (output points) at which the force contributing to the torque for rotating the output shaft portion 40 about the axis AX is transmitted from the flex gear portion 20 to the output shaft portion 40. , the torque can be earned.

(5) Furthermore, as shown in FIGS. 9(a) and 9(b), there are N fixed parts 60 as pole-corresponding fixing parts, and the auxiliary fixing parts 60a are pole-corresponding fixing parts adjacent in the circumferential direction. It may be provided at a position that avoids an intermediate position.

(6) The wave gear device 100 further includes a support portion 50 that rotatably supports the output shaft portion 40 with respect to the internal gear portion 30, and the adjacent portion 22 and the opposing portion 41 are connected to the support portion 50 and the cam portion 12. located between.
According to this configuration, as described above, the axial length from the cam part 12 to the output point of the flex gear part 20 (that is, the position of the fixed part 60 that transmits force from the flex gear part 20 to the output shaft part 40) Therefore, each structure can be made compact in the axial direction, and the strain wave gear device 100 can be configured in a small size. If the length to the output point can be suppressed in this way, one tooth ridge and the other tooth bottom in the flex gear section 20 and internal gear section 30 can be brought into contact along the axial direction, and the gears of each other can be brought into contact with each other along the axial direction. Wear can also be suppressed. Note that the support portion 50 is not limited to a cross roller bearing, and may be a ball bearing, a bearing that slides and rotatably supports the output shaft portion 40, or the like.

(7) One fixing portion (fixing portion 60 or auxiliary fixing portion 60a) includes one or more fixing pins F that fix the adjacent portion 22 to the opposing portion 41 in a radial direction centered on the axis AX.
In addition, in the above explanation, an example was shown in which the adjacent part 22 of the flex gear 20 is fixed to the opposing part 41 of the output shaft part 40 from the outer circumferential side to the inner circumferential side with the fixing pin F, but from the inner circumferential side It is also possible to adopt a mode in which the fixing pin F is used to fix the fixing pin F toward the outer circumferential side. However, it is preferable to fix the adjacent portion 22 to the opposing portion 41 from the outer circumferential side to the inner circumferential side with the fixing pin F, since this can suppress the device from increasing in size in the radial direction around the axis AX. It is.

(8) Furthermore, it is preferable that the number t of teeth of the outer gear 21 is N fewer than the number T of teeth of the inner gear 31 (t=TN).

In the above description, descriptions of known technical matters have been omitted as appropriate in order to facilitate understanding of the present invention.

DESCRIPTION OF SYMBOLS 100... Wave gear device 10... Wave generation part 11... Cylindrical shaft part, 12... Cam part, 13... Wave bearing 20... Flex gear part 21... Outer gear, 22... Adjacent part 30... Internal gear part 31... Inner gear 40... Output shaft Part 41...Opposing part, 42...Supported part 50...Supporting part 60...Fixing part, 60a...Auxiliary fixing part, F...Fixing pin 200...Robot, 201...Base 210...Robot body part 211...First arm, 212 ...Second arm, 213...Motor 220...Controller

Claims (6)

an internal gear portion having an inner gear formed along the inner peripheral surface;
a wave generating section having a cam section that rotates around an axis in response to a rotational input;
A flex having a ring-shaped outer gear formed along an outer peripheral surface with a smaller number of teeth than the inner gear, the inner peripheral side of which is fitted into the wave generation part, and an adjacent part adjacent to the outer gear in a direction along the axis. The gear part and
an output shaft portion having a facing portion that faces the adjacent portion in a radial direction centered on the axis, and rotating with respect to the internal gear portion together with the flex gear portion;
a fixing part that fixes the flex gear part to the output shaft part by partially fixing the adjacent part to the opposing part in a circumferential direction centering on the axis;
The cam portion has N (N is an integer of 2 or more) pole portions located at equal intervals in the circumferential direction, and engages the outer gear with the inner gear at N locations,
There are multiple fixing parts,
N pole-corresponding fixing parts arranged at equal intervals in the circumferential direction,
not provided at an intermediate position between the pole-compatible fixing parts adjacent in the circumferential direction;
Wave gear device. The plurality of fixing parts further include an auxiliary fixing part provided in a position different from the pole corresponding fixing part in the circumferential direction , and provided at a position avoiding the intermediate position .
The wave gear device according to claim 1 . The auxiliary fixing parts are plural and arranged at equal intervals in the circumferential direction.
The wave gear device according to claim 2 . further comprising a support part that rotatably supports the output shaft part with respect to the internal gear part,
The adjacent part and the opposing part are located between the support part and the cam part,
The wave gear device according to any one of claims 1 to 3 . one of the fixing parts includes one or more fixing pins fixing the adjacent part to the opposing part in the radial direction;
The wave gear device according to any one of claims 1 to 4 . The number of teeth of the outer gear is N fewer than the number of teeth of the inner gear.
The wave gear device according to any one of claims 1 to 5 .