WO2017022062A1

WO2017022062A1 - Strain wave gearing device

Info

Publication number: WO2017022062A1
Application number: PCT/JP2015/072001
Authority: WO
Inventors: 純半田; 木村　浩明; 崇太郎三宅; 小林　優; 達郎保科; 啓長井
Original assignee: 株式会社ハーモニック・ドライブ・システムズ
Priority date: 2015-08-03
Filing date: 2015-08-03
Publication date: 2017-02-09

Abstract

A flat strain wave gearing device is provided with a first internal gear (2) that is obtained from a helical gear, and a second internal gear (3) that is obtained from a helical gear, the helix direction of which is the reverse of the first internal gear (2). The first and second external gear portions (4A, 4B) of an external gear (4) that mesh respectively with the first and second internal gears (2, 3) are also helical gears. Since the meshing of the first and second internal gears (2, 3) with the external gear (4) is a meshing between helical gears of opposite helix directions, thrusts that are generated by the meshing offset each other. Since no thrust force moving said external gear (4) in the axial direction is generated in the external gear (4), a member for preventing movement of the external gear in the axial direction is unnecessary.

Description

Wave gear device

The present invention relates to a wave gear device using a helical gear as a flexible gear.

As a wave gear device, a flat type wave gear device including two rigid internal gears and a cylindrical flexible external gear arranged inside thereof is known. In the flat wave gear device, due to the mechanism, a thrust force is generated in the external gear during operation. In the flat wave gear devices described in

Patent Documents

1 and 2, the restricting members are arranged on both sides of the external gear so that the external gear does not move in the axial direction by the thrust force.

Moreover, as a wave gear apparatus, the cup-shaped wave gear apparatus provided with the cup-shaped flexible external gear of patent document 3 and the silk hat-shaped flexible external gear of patent document 4 are used. A top-hat type wave gear device provided is known. The external gear includes a flexible cylindrical body having external teeth formed on the outer peripheral surface, and a diaphragm extending radially inward or outward from the rear end of the cylindrical body. External teeth are formed on the outer peripheral surface portion on the opening end side.

Since the external gear is bent in an elliptical shape by a wave generator fitted inside the external tooth forming portion, the external tooth forming portion of the cylindrical body portion is directed from the diaphragm side toward the opening end side. The amount of bending in the radial direction increases substantially in proportion to the distance from. As described above, since the amount of ellipse is different at each position in the tooth trace direction, an attempt is made to move the external tooth forming portion in the axial direction on the inner peripheral surface of the external tooth forming portion of the external gear bent by the wave generator. Thrust force is generated. Due to the thrust force, the stress generated in the portion between the cylindrical body portion of the external gear and the diaphragm is increased.

JP 2011-110976 A JP 2013-177938 A JP 2012-0729212 A JP 2009-257510 A

In a flat wave gear device, if a restricting member is arranged to restrict movement in the axial direction due to the thrust force acting on the external gear, the size of the device and the cost increase accordingly. The thrust force acting on the external gear acts on a wave generator that is bending the external gear. Therefore, the life of the support portion such as the support bearing of the wave generator is reduced. In order to avoid shortening the service life, when the components of the support mechanism are strengthened, the apparatus is increased in size and cost.

Also, in a cup-type or top-hat type wave gear device, it is desirable that stress generated in a diaphragm or the like due to a thrust force acting on an external gear can be reduced in order to increase transmission torque.

In view of these points, an object of the present invention is to provide a flat wave gear device configured such that a flexible gear does not move in the axial direction without using a separate member.

Another object of the present invention is to provide a wave gear device configured such that the axial movement of the flexible gear due to the thrust force acting on the inner peripheral surface of the flexible gear is canceled by the meshing tooth surfaces of both gears. There is.

In the flat wave gear device of the present invention, at least one of the first and second rigid gears, the first rigid gear, and the first flexible gear meshing with the first rigid gear in the flexible gear. The portion is a helical gear or a helical gear.

That is, the flat wave gear device according to the present invention includes a first and second rigid gears and a first flexible gear that is bent in a non-circular shape and a part of the circumferential direction meshes with the first rigid gear. And a flexible gear with a second flexible gear portion meshing with the portion and the second rigid gear. The first rigid gear and the first flexible gear portion are any one of a spur gear, a helical gear, and a toothed gear.

When the first rigid gear and the first flexible gear part are the spur gears, the second rigid gear and the second flexible gear part are blind gears.

When the first rigid gear and the first flexible gear part are the helical gears, the second rigid gear and the second flexible gear part are the first rigid gear and the first flexible gear part. A helical gear having a twist direction opposite to that of the flexible gear portion is used.

When the first rigid gear and the first flexible gear portion are the toothed gears, the second rigid gear and the second flexible gear portion are either a spur gear or a toothed gear. Or one.

In the flat wave gear device of the present invention, the helical force or the helical gear is used for the first and second rigid gears and the flexible gear, so that the thrust force applied to the flexible gear during operation is reduced. It is countered or the thrust force is reduced. Moreover, the movement of the flexible gear in the axial direction is restrained with respect to the rigid gear due to the meshing of the toothed gears. As a result, the flexible gear can be prevented or suppressed from moving in the axial direction without arranging another member.

Since the thrust force generated in the flexible gear is canceled or reduced, it is possible to avoid or reduce the thrust force from acting on a support mechanism such as a bearing of a wave generator supporting the flexible gear. Therefore, it is possible to prevent or suppress the component parts of the support mechanism from being shortened due to the thrust force. In addition, it is possible to avoid or suppress the increase in size and cost of the apparatus due to the arrangement of components having a large load capacity in order to receive a large thrust force.

In the present invention, it is desirable that the helical angle of the helical gear or the helical gear is a value within a range of 5 deg to 20 deg. If it is less than 5 deg, the thrust force generated by the meshing between the first and second rigid gears and the flexible gear cannot be sufficiently suppressed. Conversely, if it exceeds 20 deg, the efficiency deteriorates, which is not preferable.

Next, the cup-type or top-hat type wave gear device of the present invention includes a rigid gear and a cup-shaped or top-hat-shaped shape that is bent in a non-circular shape and part of the circumferential direction meshes with the rigid gear. It has a flexible gear. The flexible gear is a helical gear, and a tooth portion of the flexible gear has a first helical tooth portion formed on one side in a tooth trace direction, and a second portion formed on the other side. The first helical portion and the second helical portion have different twist angles. The tooth portion of the rigid gear includes a helical tooth portion that can mesh with the first helical gear portion and a helical tooth portion that can mesh with the second helical gear portion.

剛性 Between the rigid gear and the flexible gear, there are two sets of helical gears with different torsion angles. Accordingly, the thrust force acting on the flexible gear is received by the meshing tooth surfaces of the two sets of helical teeth. Therefore, it can prevent or suppress that thrust force acts on parts, such as diaphragms other than the tooth | gear part of a flexible gear, and the stress of those parts will increase.

It is a longitudinal cross-sectional view which shows an example of the flat type wave gear apparatus to which this invention is applied. (A) is a perspective view which shows the internal gear and external gear of FIG. 1, and shows the state which cut off a part of internal gear, (b) is explanatory drawing which shows the tooth | gear part of an external gear. (A) is a perspective view which shows another example of the internal gear of FIG. 1, and an external gear, and shows it in the state which cut off a part of internal gear, (b) is explanatory drawing which shows the tooth | gear part of an external gear. . (A) is a perspective view which shows another example of the internal gear of FIG. 1, and an external gear, and shows it in the state which cut off a part of internal gear, (b) is explanatory drawing which shows the tooth | gear part of an external gear. . (A) is a half sectional view showing another example of a flat wave gear device to which the present invention is applicable, and (b) is a half front view thereof. It is the longitudinal cross-sectional view which shows an example of the cup type wave gear apparatus to which this invention is applied, and an exploded perspective view. It is a perspective view which shows the flexible external gear of FIG. 6, the partial side view which shows the tooth part, and the partial longitudinal cross-sectional view which shows a tooth part.

Hereinafter, an embodiment of a flat wave gear device to which the present invention is applied will be described with reference to the drawings.

[Embodiment 1]
FIG. 1 is a longitudinal sectional view showing a flat wave gear device according to the first embodiment. The flat wave gear device 1 has a first internal gear 2 (C / SS) and a second internal gear 3 (C / SD), which are rigid gears, and a cylindrical shape coaxially disposed inside these. And an external gear 4 that is a flexible gear, and a wave generator 5 that is fitted inside the external gear 4. One internal gear, for example, the first internal gear 2 is fixed to a fixing member such as a device housing (not shown), and the other second internal gear 3 is rotatably supported by a device housing (not shown). Connected to the driven member side.

The external gear 4 includes a cylindrical body 4c that can be bent in the radial direction, and first external teeth 4a and second external teeth 4b that are formed on a circular outer peripheral surface of the cylindrical body 4c. The first external teeth 4 a can mesh with the first internal teeth 2 a of the first internal gear 2, and the second external teeth 4 b can mesh with the second internal teeth 3 a of the second internal gear 3. A first external gear portion 4A is formed by the cylindrical body portion 4c and the first external teeth 4a, and a second external gear portion 4B is formed by the cylindrical body portion 4c and the second external teeth 4b.

The wave generator 5 includes a rigid plug 5a having an elliptical outer peripheral surface and a pair of

wave generator bearings

5b and 5c attached to the elliptical outer peripheral surface of the plug 5a. As a whole, the

wave generator bearings

5b and 5c are bent in an elliptical shape along the elliptical outer peripheral surface of the plug 5a. Therefore, the external gear 4 is also bent in an elliptical shape along the elliptical outer peripheral surface of the plug 5a, and the first and second

external gears

4a and 4b at the major axis positions thereof are the first and second

internal gears

2 and 3. The first and second

internal teeth

2a and 3a are engaged with each other. When the wave generator 5 is rotated, the meshing positions between the external gear 4 and the first and second

internal gears

2 and 3 are respectively moved in the circumferential direction.

For example, the number of teeth of the second internal gear 3 is the same as that of the first and second

external gear portions

4A and 4B, and the number of teeth of the other first internal gear 2 is based on the first and second

external gear portions

4A and 4B. Is 2n more (n: positive integer). For example, there are two more. Accordingly, the external gear 4 (the first and second

external gear portions

4A and 4B) rotates integrally with the second internal gear 3 having the same number of teeth, and between the first internal gear 2 having a large number of teeth. Causes relative rotation according to the difference in the number of teeth of both gears. Since the first internal gear 2 is fixed so as not to rotate, a reduced rotation is output from the other second internal gear 3 and transmitted to a driven member (not shown).

FIG. 2A is a perspective view showing the first and second

internal gears

2 and 3 and the external gear 4, and the first and second

internal gears

4a and 4b are shown to show the first and second

external teeth

4a and 4b. The

gears

2 and 3 are partially cut off. FIG. 2 (b) is an explanatory view showing the tooth portions of the first and second external gear portions 4 </ b> A and 4 </ b> B of the external gear 4.

As can be seen from these drawings, the first and second

external gear portions

4A and 4B of the external gear 4 are helical external gears, and the first and second

internal gears

2 and 3 can also mesh with them. This is an internal gear. The first external tooth 4a of one first external gear portion 4A of the external gear 4 is a helical tooth whose tooth trace direction has a constant helix angle with respect to the direction of the central axis 1a. On the other hand, the second external teeth 4b of the second external gear portion 4B are helical teeth extending at the same helix angle in the opposite direction to the first external teeth 4a. Similarly, the first and second

internal teeth

2a and 3a of the first and second

internal gears

2 and 3 are helical teeth twisted in directions opposite to each other.

Thus, the first and second

external gear portions

4A and 4B are helical external gears whose torsional directions are reversed, and the first and second internal gears meshing with these are also helical teeth whose reverse torsional directions are reversed. It is an internal gear. Since the helical gears having opposite torsional directions are arranged in parallel in the direction of the central axis 1a, the thrust force generated by the meshing of the first internal gear 2 and the first external gear portion 4A, and the second internal gear 3 The thrust force generated by the meshing of the second external gear portion 4B acts in the opposite direction. Therefore, the thrust force generated by the meshing is offset or reduced.

(Modification 1)
FIG. 3A is a perspective view showing an example of the first and second internal gears and the external gear that can be used in place of the first and second

internal gears

2 and 3 and the external gear 4. FIG. 3B is an explanatory diagram showing the tooth portions of the first and second external gear portions of the external gear.

As shown in these drawings, in this example, the first external gear portion 14A of the external gear 14 is a spur gear, and the second external gear portion 14B is a toothed external gear. Correspondingly, the first internal gear 12 is a spur gear that can mesh with the first external gear portion 14A, and the second internal gear 13 is a toothed internal gear that can mesh with the second external gear portion 14B. .

スラ Thrust force generated by the meshing is offset at the meshing part between the toothed gears. Therefore, the thrust force acting on the external gear 14 is reduced as a whole. Further, the movement of the external gear 14 in the axial direction is restrained by the meshing of the toothed gears.

(Modification 2)
FIG. 4A is a perspective view showing another example of the first and second internal gears and the external gear that can be used in place of the first and second

internal gears

2 and 3 and the external gear 4. FIG. 4B is an explanatory view showing the tooth portions of the first and second external gear portions of the external gear, with a part of the first and second internal gears being cut off.

As shown in these drawings, in this example, the first external gear portion 24A of the external gear 24 is a toothed external gear, and the second external gear portion 24B is also a toothed external gear. Correspondingly, the first internal gear 22 is a toothed internal gear that can mesh with the first external gear portion 24A, and the second internal gear 23 is a toothed internal gear that can mesh with the second external gear portion 24B. is there.

スラ Thrust force is offset by the meshing of the toothed gears. Therefore, the thrust force acting on the external gear 14 is canceled out. The external gear 14 does not move in the axial direction.

As described above, in the flat wave gear device of the present invention, the meshing between the first and second internal gears and the external gear is such that the meshing of the helical teeth or the meshing of the tooth teeth. ing. Therefore, the thrust force generated in the

external gears

4, 14, and 24 can be offset or reduced. Therefore, a member for restricting or restraining the movement of the external gear in the axial direction can be omitted. Further, the meshing between the helical gears or between the toothed gears is smoother than the meshing between the spur gears, which is advantageous for low vibration and low noise.

Furthermore, since the member for restricting the movement of the external gear can be omitted, it is possible to secure a space for distributing the lubricant on both sides in the axial direction of the meshing portion of the internal gear and the external gear. Thereby, the incidental effect that the lack of lubrication to the meshing part or the like can be solved is also obtained.

[Embodiment 2]
FIG. 5A is a half cross-sectional view showing an example of another type of flat wave gear device to which the present invention is applicable, and FIG. 5B is a half front view thereof. The flat wave gear device 30 shown in these drawings includes a first external gear 32 and a second external gear 33 that are rigid gears, and an internal gear that is a cylindrical flexible gear that is coaxially disposed on the outer sides thereof. 34 and a wave generator 35 fitted to the outside of the internal gear 34.

The internal gear 34 includes a cylindrical body portion 34c that can be bent in the radial direction, and first internal teeth 34a and second internal teeth 34b that are formed on the circular inner peripheral surface of the cylindrical body portion 34c. The first internal teeth 34 a can mesh with the first external teeth 32 a of the first external gear 32, and the second internal teeth 34 b can mesh with the second external teeth 33 a of the second external gear 33. A first internal gear portion 34A is formed by the cylindrical body portion 34c and the first internal teeth 34a, and a second internal gear portion 34B is formed by the cylindrical body portion 34c and the second internal teeth 34b.

The wave generator 5 includes a rigid plug 35a having a constant thickness provided with an elliptical inner peripheral surface, and a pair of wave generator bearings 35b attached to the elliptical inner peripheral surface of the plug 35a. The wave generator bearing 35b as a whole is bent in an elliptical shape along the elliptical inner peripheral surface of the plug 35a. Accordingly, the internal gear 34 is also bent in an elliptical shape along the elliptical inner peripheral surface of the plug 35a, and the first and second

internal gears

34a and 34b at the short diameter position thereof are the first and second external gears 32. , 33 are engaged with the first and second

external teeth

32a, 33a. When the wave generator 35 is rotated, the meshing positions between the internal gear 34 and the first and second

external gears

32 and 33 are respectively moved in the circumferential direction.

In the flat wave gear device 30 having this configuration, the first external gear 32 and the first internal gear portion 34A are any one of a spur gear, a helical gear, and a helical gear.

When the first external gear 32 and the first internal gear portion 34A are spur gears, the second external gear 33 and the second internal gear portion 34B are bevel gears.

When the first external gear 32 and the first internal gear portion 34A are helical gears, the second external gear 33 and the second internal gear portion 34B are different from the first external gear 32 and the first internal gear portion 34A. A helical gear having a reverse twist direction is used.

When the first external gear 32 and the first internal gear portion 34A are toothed gears, the second external gear 33 and the second internal gear portion 34B are either a spur gear or a toothed gear. Is done.

Also in the flat wave gear device 30 having this configuration, the same effects as those of the flat wave gear device 1 can be obtained.

[Embodiment 3]
FIG. 6A is a longitudinal sectional view showing a cup-type wave gear device to which the present invention is applied, and FIG. 6B is an exploded perspective view thereof. The wave gear device 100 includes an internal gear 102 that is a rigid gear, and an external gear 103 that is a cup-shaped flexible gear disposed inside the wave gear device 100. The outer gear 103 includes a cylindrical body 103a that can be bent in the radial direction, a diaphragm 103b that extends radially inward from the rear end thereof, and a thick wall formed continuously on the inner periphery of the diaphragm 103b. And an annular or disc-shaped boss 103c. A portion of the cylindrical body 103a on the opening side is an external tooth forming portion 103d, and external teeth 103e are formed on the outer peripheral surface portion thereof.

The cylindrical body portion 103 a of the external gear 103 is bent in an elliptical shape by a wave generator 104 having an elliptical contour that is attached to the inside of the external tooth forming portion 103 d, and the external teeth 103 e are connected to the internal gear 102. It partially meshes with the internal teeth 102a. When the wave generator 104 is rotated, the meshing position of the two

gears

102 and 103 moves in the circumferential direction, and relative rotation corresponding to the difference in the number of teeth of the two

gears

102 and 103 is generated between the two gears. When one gear, for example, the internal gear 102 is fixed so as not to rotate, reduced rotation is output from the other cup-shaped external gear 103.

The wave generator 104 includes a ring-shaped, rigid plug 104a having a constant thickness, and a wave generator bearing 104c attached to an elliptical outer peripheral surface 104b of the plug 104a. The wave generator bearing 104 c includes inner and outer rings that can be bent in the radial direction, and is mounted between the plug 104 a and the outer gear 103. The external gear 103 is bent into an elliptical shape along the elliptical outer peripheral surface 104b of the plug 104a by the wave generator 104, and the external teeth 103e mesh with the internal teeth 102a of the internal gear 102 at a position on the long axis. .

7A is a perspective view showing the external gear 103, and FIGS. 7B and 7C are a partial side view and a partial cross-sectional view showing an external tooth forming portion 103d of the external gear 103. FIG. 7B and 7C, the external teeth 103e are schematically shown for easy understanding of the shape of the external teeth 103e.

As shown in these drawings, the external gear 103 is a helical external gear, and the external tooth 103e is formed by an annular constant width groove 111 formed at the center in the direction of the tooth stripe, so that the first helical gear portion is formed. 112 and the second helical tooth portion 113 are separated. The first helical tooth portion 112 on the open end side of the external gear 103 is a helical tooth twisted at a constant twist angle with respect to the direction of the central axis 101a. On the other hand, the second helical tooth portion 113 on the diaphragm side is a helical tooth having a torsion angle different from that of the first helical tooth portion 112. The groove 111 is a single annular groove extending in the circumferential direction along the circular outer peripheral surface (the root circle) of the root rim 110 of the external tooth forming portion 103d.

The internal gear 102 is a helical internal gear that can mesh with the external gear 103 as shown in FIG. The internal teeth 102 a of the internal gear 102 include a helical tooth portion 122 that can mesh with the first helical tooth portion 112 and a helical tooth portion 123 that can mesh with the second helical tooth portion 113. These are separated by a groove 121.

Thrust force acts on the inner peripheral surface of the tooth portion of the external gear 103 that is bent into an elliptical shape by the wave generator 104 and meshes with the internal gear 102. Between the two gears, two sets of helical teeth with different twist angles are formed. The meshing tooth surfaces of these two sets of helical teeth receive a thrust force, and the thrust force can be prevented or suppressed from acting on a portion of the external gear 103 such as the diaphragm 103b.

[Other embodiments]
In the third embodiment, the present invention is applied to a cup-type wave gear device. The present invention can be similarly applied to a top hat type wave gear device.

Claims

First and second rigid gears, and
A first flexible gear portion that is non-circularly bent and a portion of the circumferential direction meshes with the first rigid gear and a second flexible gear portion that meshes with the second rigid gear. A flexible gear,
The first rigid gear and the first flexible gear part are any one of a spur gear, a helical gear, and a toothed gear,
When the first rigid gear and the first flexible gear portion are the spur gear, the second rigid gear and the second flexible gear portion are toothed gears,
When the first rigid gear and the first flexible gear part are the helical gears, the second rigid gear and the second flexible gear part are the first rigid gear and the first flexible gear part. A helical gear with a twist direction opposite to that of the flexible gear portion,
When the first rigid gear and the first flexible gear portion are the toothed gears, the second rigid gear and the second flexible gear portion are either a spur gear or a toothed gear. On the other hand, a flat wave gear device.
2. The flat wave gear device according to claim 1, wherein the first and second rigid gears are internal gears, and the flexible gear is an external gear.
2. The flat type wave gear device according to claim 1, wherein the helical angle of the helical gear or the helical gear is a value within a range of 5 deg to 20 deg.
Rigid gears, and
A cup-shaped or top hat-shaped flexible gear that is bent non-circularly and a portion in the circumferential direction meshes with the rigid gear;
The flexible gear is a helical gear;
The tooth portion of the flexible gear is separated into a first helical tooth portion formed on one side in the tooth trace direction and a second helical tooth portion formed on the other side,
The first helical tooth portion and the second helical tooth portion have different twist angles.
The tooth portion of the rigid gear includes a helical gear portion that can mesh with the first helical gear portion, and a helical gear portion that can mesh with the second helical gear portion.
The wave gear device according to claim 4, wherein the rigid gear is an internal gear, and the flexible gear is an external gear.