JP7145492B2 - Decelerator - Google Patents

Description

TECHNICAL FIELD The present invention relates to a speed reducer that reduces and transmits rotational power, and more particularly to a speed reducer that can be made thinner.

A motor is used as a power generator in a joint driving device for driving the joints of a robot. There may be Therefore, in a joint driving device or the like, a speed reducer that reduces rotational power and transmits it is usually used. However, if the size of the speed reducer is increased, the size of the joint driving device and the like is also increased. A planetary gear speed reducer has been conventionally used as a speed reducer that can be made thinner in this way, but it has been difficult to increase the reduction ratio sufficiently in the planetary gear speed reducer.

Therefore, various speed reducers have been developed that can be made thinner and have a sufficiently high speed reduction ratio. For example, in Patent Document 1, an internal gear using a cylindrical outer pin as a tooth profile, and a curved plate that functions as a planetary gear with an epitrochoid parallel curve on the outer periphery are formed, and the curved plate is eccentrically oscillated. A constant velocity internal gear mechanism that extracts only the slowed rotation of the curved plate by inserting a cylindrical inner pin into a circular inner pin hole formed in the curved plate. A cycloid reducer is described that combines the two mechanisms of Such a cycloid reducer can reduce the difference in the number of teeth between the internal gear and the planetary gear, and thus can increase the reduction ratio.

However, in the cycloid reducer, it is necessary to convert the rotary motion into eccentric oscillation of the curved plate in the internal planetary gear mechanism, and extract only the rotation of the curved plate in the constant velocity internal gear mechanism. Therefore, the cycloid reducer needs to be provided with an eccentric body having a cylindrical portion eccentric with respect to the central axis of rotational motion, a carrier fixed with the inner pin projecting, and the like. As described above, the cycloid speed reducer has a complicated structure for realizing the operation as a speed reducer, and it is difficult to simplify the structure.

Japanese Unexamined Patent Application Publication No. 2016-201996

Thus, it has been difficult to increase the speed reduction ratio and simplify the structure of the speed reducer itself in a speed reducer that can be made thinner. This problem is not limited to speed reducers used in robots and the like, but is common to speed reducers used in various fields.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned conventional problems. intended to provide

In order to achieve at least part of the above objects, the present invention can be implemented as the following forms or application examples.
A speed reducer according to one aspect of the present invention includes a housing, an input gear housed in the housing and receiving power to rotate about a rotation axis of the speed reducer, and a fixed gear fixed to the housing. , and a front stage portion, which is a gear mechanism in which an oscillating drive gear meshing with both the input gear and the fixed gear is arranged in a nested state; a rear-stage portion that is a gear mechanism in which a driven rocking gear and an output gear that meshes with the driven rocking gear and outputs reduced power to rotate about the rotation shaft are arranged in a nested state; The input gear is formed with a first external gear centered on the rotation shaft, and the oscillating drive gear is provided with a first internal gear meshing with the first external gear and a second external gear. The fixed gear is formed coaxially with the second internal gear meshing with the second external gear and centered on the rotation shaft, and the driven oscillating gear is formed with the first internal gear. and a third external gear coaxial with the second external gear, and the output gear is formed with a third internal gear meshing with the third external gear and centered on the rotation shaft. The modules of the first to third external gears and the modules of the first to third internal gears are all set to be the same, and the difference in the number of teeth between the internal gear and the external gear that mesh with each other is all the same. It is characterized by being set.
According to this aspect, the reduction ratio of the speed reducer can be made sufficiently high by appropriately setting the configuration of the gears. Moreover, according to this aspect, the front stage portion and the rear stage portion that realize the speed reduction function can be arranged along the rotation axis. Since the input gear, oscillating drive gear, and fixed gear of the front stage and the driven oscillating gear and output gear of the rear stage can all be made sufficiently thin, the speed reducer can be made sufficiently thin. can do. Furthermore, according to this application example, the operation as a speed reducer is realized by the input gear, the oscillating drive gear, the fixed gear, the driven gear and the output gear. Since these gears can be configured as gears having general external gears and internal gears, it is possible to simplify the structure of the speed reducer itself.
In addition, according to this aspect, since the modules are set to be the same for all the external gears and the internal gears, the input gear, the oscillating drive gear, the fixed gear, the driven oscillating gear, and the output gear that constitute the reduction gear are Can be designed more easily.

[Application example 1]
A speed reducer comprising: a housing; an input gear accommodated in the housing and receiving power to rotate about a rotation axis of the speed reducer; a fixed gear fixed to the housing; a front stage portion which is a gear mechanism in which an oscillating drive gear meshing with both the gear and the fixed gear is arranged in a nested state; a driven oscillating gear housed in the housing and fixedly attached to the oscillating drive gear; and a rear stage portion which is a gear mechanism in which an output gear that meshes with the driven rocking gear and outputs reduced power to rotate about the rotation shaft is arranged in a nested state, wherein the front stage portion is provided with power is input to rotate the input gear around the rotation axis, the oscillation drive gear rotates and oscillates while the axis of the oscillation drive gear draws an oscillation circle centered on the rotation axis. When the driven oscillating gear rotates and oscillates so that the shaft of the driven oscillating gear coaxial with the oscillating drive gear draws the oscillating circle, the rear stage portion A reduction gear, wherein an output gear is configured to rotate about the rotation axis.

According to this application example, the reduction ratio of the speed reducer can be made sufficiently high by appropriately setting the configuration of the gears. Further, according to this application example, the front stage portion and the rear stage portion that realize the deceleration function can be arranged along the rotation axis. Since the input gear, oscillating drive gear, and fixed gear of the front stage and the driven oscillating gear and output gear of the rear stage can all be made sufficiently thin, the speed reducer can be made sufficiently thin. can do. Furthermore, according to this application example, the operation as a speed reducer is realized by the input gear, the oscillating drive gear, the fixed gear, the driven gear and the output gear. Since these gears can be configured as gears having general external gears and internal gears, it is possible to simplify the structure of the speed reducer itself.

[Application example 2]
In the speed reducer according to Application Example 1, the input gear is formed with a first external gear centered on the rotation shaft, and the oscillating drive gear is provided with a first external gear that meshes with the first external gear. and a second external gear are formed coaxially, and the fixed gear is formed with a second internal gear that meshes with the second external gear and has the rotation axis as an axis, and the slave The oscillating gear is formed with a third external gear coaxial with the first internal gear and the second external gear, and the output gear meshes with the third external gear and rotates the rotation shaft. A third internal gear is formed as a shaft, and the modules of the first to third external gears and the modules of the first to third internal gears are all set to be the same, and the internal gears mesh with each other. A speed reducer in which the difference in the number of teeth from the external gear is all set to be the same.

According to this application example, since the same module is set for all the external gears and the internal gears, the input gear, the oscillating drive gear, the fixed gear, the driven oscillating gear, and the output gear, which constitute the reduction gear, can be easily assembled. can be designed to

[Application Example 3]
The speed reducer according to application example 2, wherein the same tooth number difference is set to an odd number.

According to this application example, it is possible to suppress the occurrence of a reverse rotation phenomenon in which the output gear rotates in the opposite direction depending on the rotation state of each gear when the rotation of the input gear is started.

[Application example 4]
3. The speed reducer according to Application Example 3, wherein the difference in the number of teeth set to be the same is set to one.

According to this application example, the speed reduction ratio of the speed reducer can be made higher.

[Application example 5]
5. The speed reducer according to any one of application examples 1 to 4, wherein tooth profiles of the input gear, the oscillating drive gear, the fixed gear, the driven oscillating gear, and the output gear are cycloidal tooth profiles.

According to this application example, it becomes easier to reduce the backlash of the speed reducer and reduce the difference in the number of teeth to increase the speed reduction ratio.

It should be noted that the present invention can be implemented in various modes. For example, it can be realized in the form of a speed reducer, a drive mechanism using the speed reducer, or a driving device combining the speed reducer and a power generation device such as a motor.

1 is an exploded perspective view showing the configuration of a speed reducer as one embodiment of the present invention; FIG. Explanatory drawing which shows operation|movement of a front stage part. Explanatory drawing which shows operation|movement of a front stage part. Explanatory drawing which shows operation|movement of a latter part. Explanatory drawing which shows operation|movement of a latter part.

DETAILED DESCRIPTION OF THE INVENTION Embodiments for carrying out the present invention will be described in the following order.
A. Embodiment:
A1. Reducer configuration:
A2. Operation of reducer:
B. Variant:

A. Embodiment:
A1. Reducer configuration:
FIG. 1 is an exploded perspective view showing the configuration of a speed reducer 100 as one embodiment of the present invention. The speed reducer 100 reduces the power that is input to the speed reducer 100 and rotates about the central axis C of the speed reducer 100 to reduce the power that rotates about the central axis C (hereinafter referred to as "rotational power" or simply " (also called power). Thus, the central axis C becomes the center of rotation of power input to and output from the speed reducer 100 . Therefore, the central axis C can also be called a "rotational axis". In the speed reducer 100 of the present embodiment, rotational power is input along the central axis C from the right side of the paper surface of FIG. 1 and output from the left side. Therefore, in FIG. 1, the right side of the paper along the central axis C is also called the "input side", and the left side of the paper is also called the "output side".

As shown in FIG. 1 , the speed reducer 100 of this embodiment includes a front stage portion 101 and a rear stage portion 102 that are a combination of gears (gear mechanism) that mesh with each other, an input shaft 105 , and a housing 160 . The front stage portion 101 is configured by arranging three plate-shaped gears 110, 120, and 130 having approximately the same thickness in a nested state, and the rear stage portion 102 is configured by two plate-shaped gears 140 and 140 having approximately the same thickness. 150 are arranged in a nested state. In the following description, these five gears 110 to 150 will also be referred to as an input gear 110, an oscillating drive gear 120, a fixed gear 130, a driven oscillating gear 140, and an output gear 150, corresponding to their operations and functions to be described later. call.

The housing 160 has a cylindrical tubular portion 161 , a disk-shaped plate-shaped portion 162 , and six ear portions 165 provided on the outer periphery of the tubular portion 161 . The plate-like portion 162 is fixedly attached inside the input-side end of the cylindrical portion 161 . A shaft hole 169 for passing the input shaft 105 is provided in the plate-like portion 162 . A through hole 168 for fixing the speed reducer 100 to the outside is formed at the boundary between the cylindrical portion 161 and the ear portion 165 .

A housing 160 fixed to the outside serves as a reference for the operation of each part of the speed reducer 100 . Therefore, hereinafter, operations of each part such as rotation will be described with reference to the housing 160 unless otherwise specified. Further, the rotation state of each part will be described as rotation about the central axis C unless otherwise specified.

The input gear 110 , the oscillating drive gear 120 and the fixed gear 130 that constitute the front stage portion 101 are accommodated inside the cylindrical portion 161 so as to be adjacent to the output side of the plate-like portion 162 . The driven rocking gear 140 and the output gear 150 that constitute the rear stage portion 102 are housed inside the tubular portion 161 so as to be adjacent to the output side of the front stage portion 101 .

As described above, in the speed reducer 100 of the present embodiment, the front stage portion 101 and the rear stage portion 102, which are the main components, are arranged along the central axis C in a state of being adjacent to each other. Moreover, the thickness of each of the five gears 110 to 150 forming the front stage portion 101 and the rear stage portion 102 can be made sufficiently thin. Therefore, according to this embodiment, the speed reducer 100 can be made thinner.

As shown in FIG. 1, the inner diameter of the shaft hole 169 provided in the plate-like portion 162 is set larger than the outer diameter of the input shaft 105 and smaller than the addendum circle diameter of the input gear 110. there is Therefore, the movement of the input gear 110 and the swing drive gear 120 of the front stage portion 101 toward the input side is restricted by the plate-like portion 162 . Further, the driven oscillating gear 140 and the output gear 150 of the rear stage 102 are restricted from moving toward the input side by the oscillating drive gear 120 and the fixed gear 130 of the front stage 101 .

Further, the movement of the input gear 110 and the oscillating drive gear 120 of the front stage 101 and the driven oscillating gear 140 and the output gear 150 of the rear stage 102 to the output side is restricted. This can be done by arranging a member (not shown) that regulates the movement, or by appropriately configuring output means (not shown) that outputs rotational power from the output gear 150 so as to regulate the movement.

The input shaft 105 is a cylindrical member centered on the central axis C, and is fixedly attached to the input gear 110 in a state of protruding toward the input side through the shaft hole 169 of the plate-like portion 162 . The input shaft 105 and the input gear 110 rotate about the central axis C by inputting rotational power from the portion of the input shaft 105 that protrudes toward the input side.

For mounting the input shaft 105 to the input gear 110, for example, a threaded hole having an internal thread is provided in the end surface of the output side of the input shaft 105, and a through hole corresponding to the threaded hole is provided in the input gear 110. This can be done by tightening the male thread passing through the through hole of 110 and the female thread of the input shaft 105 . It is also possible to attach the input shaft 105 to the input gear 110 by providing the input gear 110 with a shaft fitting hole having substantially the same diameter as the input shaft 105 and fitting the input shaft 105 into the shaft fitting hole.

As shown in FIG. 1, the input gear 110 is formed with an external gear 111 coaxial with the central axis C and having six teeth. In the present embodiment, the tooth profile of the external gear 111 reduces the backlash of the speed reducer 100 and further reduces the difference in the number of teeth (difference in the number of teeth) between the external gear 111 and the internal gear 129 that meshes with it. A cycloidal tooth profile is used for ease of use. Similarly, in this embodiment, other external gears 121, 141 and internal gears 129, 139, 159, which will be described later, employ cycloidal tooth profiles as their tooth profiles.

However, the tooth profiles of the external gears 111, 121, 141 and the internal gears 129, 139, 159 (the tooth profiles of the gears 110 to 150) do not necessarily have to be cycloidal, and may be trochoidal or involute. is. In this case, if the external gear and the internal gear that mesh with each other have the same tooth profile, it is possible to employ a plurality of types of tooth profiles. However, since it is easier to reduce the backlash and it is easier to reduce the difference in the number of teeth between the external gear and the internal gear that mesh with each other, the tooth profile of the external gear and the internal gear is cycloidal. It is preferred to employ a tooth profile.

In the present embodiment, the module (value obtained by dividing the diameter of the pitch circle by the number of teeth), which is one of the parameters that define the shape of the external gears 111, 121, 141 and the internal gears 129, 139, 159 are all set the same. By setting the modules of the external gears 111, 121, 141 and the internal gears 129, 139, 159 to be the same, the external gears 111, 121, 141 and the internal gears 129, 139, 159 (gears 110 to 150) can be designed more easily.

An internal gear 139 coaxial with the central axis C and having 18 teeth is formed on the fixed gear 130 . This fixed gear 130 is fixedly mounted inside the tubular portion 161 . Such attachment of the fixed gear 130 to the cylindrical portion 161 (housing 160) is performed, for example, by fitting the fixed gear 130 into the cylindrical portion 161 or by fixing the fixed gear 130 to the housing 160 by welding or the like. It can be carried out.

In the present embodiment, the fixed gear 130 and the housing 160 are configured as separate members, but the housing may be produced by a method such as cutting, and the fixed gear may be provided in the housing itself. Further, a plate-shaped member having an outer edge corresponding to the tubular portion and the ear portion and a plate-shaped portion, a plate-shaped member having the outer edge and a fixed gear, and a plate-shaped member consisting only of the outer edge are superimposed in the direction of the central axis C to form a housing. In this way, the housing and the fixed gear fixed to the housing can be manufactured more easily.

As shown in FIG. 1, the oscillating drive gear 120 is coaxially formed with an internal gear 129 having seven teeth and an external gear 121 having seventeen teeth. As described above, input gear 110, oscillating drive gear 120 and fixed gear 130 are nested. Therefore, the oscillating drive gear 120 is arranged between the input gear 110 and the fixed gear 130 .

In this embodiment, the difference in the number of teeth between the external gear 111 of the input gear 110 and the internal gear 129 of the oscillating drive gear 120 and the difference in the number of teeth between the external gear 121 of the oscillating drive gear 120 and the internal gear 139 of the fixed gear 130 are are both set to 1. Therefore, as will be described later, the swing driving gear 120 is engaged with both the input gear 110 and the fixed gear 130, and rotates and swings as the input gear 110 rotates.

The follower oscillating gear 140 is fixedly attached to the output side of the oscillating drive gear 120 so as to be coaxial with the oscillating drive gear 120 . The attachment of the follower oscillating gear 140 to the oscillating drive gear 120 is performed by, for example, providing a threaded hole having an internal thread formed in the oscillating drive gear 120 and providing a through hole corresponding to the threaded hole in the follower oscillating gear 140 . This can be done by tightening the male thread passing through the through hole of the oscillating gear 140 and the female thread of the oscillating drive gear 120 . Alternatively, the swing drive gear 120 and the driven drive gear 140 may be fixed together by welding or the like. By fixedly attaching the driven rocking gear 140 to the rocking drive gear 120 in this manner, the driven rocking gear 140 rotates and rocks as the rocking drive gear 120 rotates and rocks.

As shown in FIG. 1, the driven oscillating gear 140 is coaxially formed with an external gear 141 having 16 teeth and a center hole 149 . In this embodiment, contact between the driven oscillating gear 140 and the input gear 110 is suppressed by providing the center hole 149 in the driven oscillating gear 140 as described above. Further, if the driven rocking gear 140 is provided with the center hole 149, when the input shaft 105 is screwed to the input gear 110 as described above, interference between the screw and the driven rocking gear 140 is suppressed. can do.

It is also possible to omit the formation of the center hole 149 provided in the driven rocking gear 140 . In this case, since the movement of the input gear toward the output side is restricted by the driven oscillating gear, there is no need to separately provide means for restricting the movement. Therefore, the configuration of the speed reducer can be simplified.

The output gear 150 has an outer diameter slightly smaller than the inner diameter of the cylindrical portion 161 and is accommodated inside the cylindrical portion 161 so as to be rotatable with respect to the housing 160 . The output gear 150 is formed with an internal gear 159 coaxial with the central axis C and having 17 teeth.

Thus, in the rear stage portion 102, the difference in the number of teeth between the external gear 141 of the driven oscillating gear 140 and the internal gear 159 of the output gear 150 is the same as the difference in the number of teeth between the external gear and the internal gear that mesh with each other in the front stage portion 101. set to the same 1. Therefore, as will be described later, in a state in which the driven rocking gear 140 and the output gear 150 are meshed with each other, the driven rocking gear 140 rotates and rocks with the rotation rocking of the rocking drive gear 120, and the rotation rocks. causes the output gear 150 to rotate.

The rotational power transmitted to the output gear 150 can be output in various ways. For example, a plate-shaped member is fixedly attached to the output side of the output gear 150, and a cylindrical output shaft having a central axis C as an axis is fixedly attached to the output side of the member, and rotational power is transmitted from the output shaft. can be output. Further, it is also possible to attach an annular member having a gear formed thereon to the output side of the output gear 150 and to output rotational power from the gear of the member.

A2. Operation of reducer:
2 and 3 are explanatory diagrams showing the operation of the front stage portion 101 in the speed reducer 100 (FIG. 1) of this embodiment. FIGS. 2(a), 2(b), 3(a) and 3(b) show, in this order, the time when rotational power is input to the input shaft 105 and the input gear 110 is rotated. change. 2 and 3 show the input gear 110, the oscillating drive gear 120, and the fixed gear 130, which constitute the front stage portion 101, viewed from the output side.

2 and 3, the "+"-shaped marker represents the central axis C of the speed reducer 100 (FIG. 1), and the "x"-shaped marker represents the axis of the oscillating drive gear 120. As shown in FIG. The two-dot chain lines represent the pitch circles of the external gears 111, 121 and the internal gears 129, 139 formed on the input gear 110, the oscillating drive gear 120 and the fixed gear 130, respectively. , the modules of the external gears 111, 121 and the internal gears 129, 139 represent circles of equal diameter. Also, the black dots drawn on the input gear 110 and the oscillating drive gear 120 are drawn to visualize their respective rotational states, and indicate the fixed positions on the input gear 110 and the oscillating drive gear 120. there is

FIG. 2(a) shows an initial state in which the input gear 110 is not rotated. In the following description, the rotation angle of the input gear 110 and the like is assumed to be ±0° in this initial state, and the rotation angle is clockwise (clockwise) when viewed from the output side. The direction of the arrow drawn around the symbol with a dot in the center) is taken as a positive value.

As described above, in this embodiment, the difference in the number of teeth between the external gear 111 of the input gear 110 and the internal gear 129 of the oscillating drive gear 120, the external gear 121 of the oscillating drive gear 120 and the internal gear 139 of the fixed gear 130 is set to 1 for both. Therefore, in the initial state shown in FIG. 2(a), the swing drive gear 120 is positioned downward from the center axis C by half the module on the paper surface (hereinafter simply referred to as "downward", etc., and the upward, rightward, and leftward also called). The external gear 111 of the input gear 110 and the internal gear 129 of the oscillating drive gear 120 are meshed upwardly in the direction opposite to the eccentric direction, so that the external gear 121 of the oscillating drive gear 120 and the internal gear 139 of the fixed gear 130 are engaged. mesh in the downward direction, which is the direction of eccentricity.

In this manner, when the input gear 110 is rotated while the oscillating drive gear 120 is in mesh with the input gear 110, the oscillating drive gear 120 rotates (rotates) around its own axis. At this time, since the fixed gear 130 meshing with the oscillating drive gear 120 does not rotate, the axis of the oscillating drive gear 120 rotates (revolves) around the central axis C as the oscillating drive gear 120 rotates.

FIG. 2(b) shows the first state in which the input gear 110 is rotated in the forward direction as indicated by the white arrow from the initial state (FIG. 2(a)), and the rotation angle of the input gear 110 becomes +20°. A rotation state (rotation state 1) is shown. At this time, the shaft of the oscillating drive gear 120 rotates about the central axis C by −85°. Also, the oscillating drive gear 120 is rotated +5° about its axis. This rotational state of the oscillating drive gear 120 corresponds to a state where the oscillating drive gear 120 revolves at a rotation angle of −85° and rotates at a rotation angle of +90°.

FIG. 3(a) shows a second rotation state (rotation state 2) in which the input gear 110 is further rotated from the first rotation state (FIG. 2(b)) and the rotation angle of the input gear 110 reaches +40°. is shown. At this time, the shaft of the oscillating drive gear 120 rotates from the initial state shown in FIG. there is Therefore, the swing drive gear 120 revolves at a rotation angle of −170° and rotates at a rotation angle of +180°.

FIG. 3(b) shows a third rotation state (rotation state 3) in which the input gear 110 is further rotated from the second rotation state (FIG. 3(a)) and the rotation angle of the input gear 110 reaches +60°. is shown. At this time, from the initial state shown in FIG. 2(a), the axis of the oscillating drive gear 120 rotates −255° around the central axis C, and the oscillating drive gear 120 rotates +15° around the axis. there is Therefore, the swing driving gear 120 revolves at a rotation angle of −255° and rotates at a rotation angle of +270°.

In this way, the swing driving gear 120 rotates and swings according to the rotation of the input gear 110 while meshing with both the input gear 110 and the fixed gear 130 . Then, as described above, the difference in the number of teeth between the external gear 111 of the input gear 110 and the internal gear 129 of the oscillating drive gear 120, and the number of teeth between the external gear 121 of the oscillating drive gear 120 and the internal gear 139 of the fixed gear 130 Since the numerical differences are all set to 1, the oscillating drive gear 120, as shown in FIGS. Rotate and oscillate to draw

Further, as shown in FIGS. 2 and 3, in the front stage portion 101 of the present embodiment, the rotation direction and the revolution direction of the oscillating drive gear 120 accompanying the rotation of the input gear 110 are opposite to each other. As described above, the rotation direction and the revolution direction of the oscillating drive gear 120 are opposite to each other. The rotation angle of the input gear 110 is smaller than that of the input gear 110 .

4 and 5 are explanatory diagrams showing the operation of the rear stage 102 of the speed reducer 100 (FIG. 1) of this embodiment. 4(a), 4(b), 5(a), and 5(b) show, in this order, the time when rotational power is input to the input shaft 105 and the input gear 110 is rotated. change. 4 and 5 show the driven rocking gear 140, the output gear 150, and the input gear 110, which constitute the rear stage 102, viewed from the output side. Symbols, arrows, markers, two-dot chain lines, dashed lines, and black dots drawn in FIGS. 4 and 5 are the same as those in FIGS. 2 and 3, so description thereof will be omitted here.

FIG. 4(a) shows an initial state in which the rotation angle of the input gear 110 is ±0°. As described above, the follower oscillating gear 140 is fixedly attached to the output side of the oscillating drive gear 120 so as to be coaxial with the oscillating drive gear 120 . Therefore, in the initial state, the driven oscillating gear 140 is eccentric downward from the center axis C by 1/2 of the module, similarly to the oscillating drive gear 120 . Since the difference in the number of teeth between the external gear 141 of the driven oscillating gear 140 and the internal gear 159 of the output gear 150 is set to 1, in the initial state, the external gear 141 of the driven oscillating gear 140 and the output gear The internal gear 159 of 150 meshes in the downward direction in the eccentric direction.

FIG. 4(b) shows a first rotation state (rotation state 1) in which the input gear 110 is rotated in the forward direction from the initial state (FIG. 4(a)) and the rotation angle of the input gear 110 becomes +20°. showing. At this time, the driven oscillating gear 140, like the oscillating drive gear 120, revolves at a rotation angle of −85° and rotates at a rotation angle of 90°. The external gear 141 of the driven oscillating gear 140 and the internal gear 159 of the output gear 150 are arranged in the eccentric direction of the driven oscillating gear 140 (that is, the direction rotated by −85° from the initial state about the central axis C). , mesh with each other.

The output gear 150 has a tooth number difference (1 in this embodiment) between the internal gear 159 of the output gear 150 and the internal gear 139 of the fixed gear 130 (FIG. 2(b)). As the gear 140 rotates and oscillates, it is decelerated at a high reduction ratio (68 in this embodiment) with respect to the input gear 110 and rotates in the opposite direction to the input gear 110 . Therefore, as shown in FIG. 4B, in rotation state 1 in which the rotation angle of the input gear 110 is +20°, the rotation angle of the output gear 150 is approximately -0.29°.

As shown in FIGS. 5(a) and 5(b), when the input gear 110 is further rotated, the driven oscillating gear 140 further rotates and oscillates, and the output gear 150 rotates accordingly. In rotational state 2 (FIG. 5A) in which the input gear 110 has a rotation angle of +40°, the driven oscillating gear 140 revolves at a rotation angle of −170° and rotates at a rotation angle of +180°. As a result, the rotation angle of the output gear 150 is about -0.58°. In rotation state 3 (FIG. 5B) in which the input gear 110 has a rotation angle of +60°, the driven oscillating gear 140 revolves at a rotation angle of −225° and rotates at a rotation angle of +270°. In this state, the rotation angle of the output gear 150 is about -0.58°.

The speed reduction ratio (absolute value of the speed transmission ratio) of such a speed reducer 100 can usually be calculated using a tabulation method or the like. Specifically, as shown in Table 1 below, the case where the input gear is rotated once while the revolution of the oscillating drive gear and the driven oscillating gear (oscillating gear) is stopped, and the case where the entire gear is glued , the number of revolutions of each of the input gear, the oscillating drive gear, the fixed gear, the driven oscillating gear, and the output gear is calculated for the case where the input gear is rotated so as to offset the rotation of the fixed gear. Next, the rotation speed of each gear in the speed reducer is calculated by adding the rotation speed of each gear under these two conditions.

In Table 1, Z ₁ , Z ₂₁ , Z ₂₂ , Z ₃ , Z ₄ , and Z ₅ are the number of teeth of the external gear of the input gear, the number of teeth of the internal gear of the oscillating drive gear, and the number of teeth of the oscillating drive gear, respectively. It represents the number of teeth of the external gear, the number of teeth of the internal gear of the fixed gear, the number of teeth of the external gear of the driven oscillating gear, and the number of teeth of the internal gear of the output gear.

After calculating the rotational speed of each gear in this manner, the speed transmission ratio j of the entire speed reducer is obtained by dividing the calculated rotational speed of the input gear by the rotational speed of the output gear. The speed transmission ratio j thus obtained is represented by the following equation (1).

Then, as in the speed reducer 100 of the present embodiment, when the difference in the number of teeth between the internal gear and the external gear that mesh with each other is 1, that is, Z ₂₁ =Z ₁ +1, Z ₂₂ =Z ₃ −1, Z ₄ = When Z ₅ -1, the speed transmission ratio j is expressed by the following equation (2).

Substituting the numbers of teeth of the external gears 111, 121, 141 and the internal gears 129, 139, 159 used in this embodiment into these equations (1) and (2), the speed transmission ratio j is calculated as follows: As mentioned above, the transmission ratio j is -68. From this, it can be seen that the input rotational power is reduced by the speed reduction ratio 68 and output with the direction of rotation reversed.

As can be seen from the above formulas (1) and (2), depending on the number of teeth, the denominator of formula (1) or formula (2) becomes zero, making it impossible to calculate the speed transmission ratio j. In this state, even if the driven oscillating gear rotates and oscillates so that its axis draws an oscillating circle, the output gear does not rotate about the central axis. Therefore, when the driven oscillating gear rotates and oscillates so that its axis draws an oscillating circle, the state in which the output gear rotates around the central axis is expressed by the denominators of the above equations (1) and (2). non-zero state, that is, Z ₃ Z ₄ −Z ₅ Z ₂₂ for general formula (1), and Z ₅ − This corresponds to _Z3 not being zero.

As described above, according to the speed reducer 100 of the present embodiment, the speed reduction ratio of the speed reducer 100 can be increased while making the speed reducer 100 thinner. In addition, in the speed reducer 100 of the present embodiment, a total of five gears, ie, the input gear 110, the oscillating drive gear 120, the fixed gear 130, the driven oscillating gear 140, and the output gear 150, can achieve a speed reducing function. , the structure of the speed reducer 100 having a high speed reduction ratio can be simplified, and its manufacture can be made easier.

Furthermore, in the speed reducer 100 of the present embodiment, there is no need to use profile shifted gears that may cause backlash or decrease in strength, unlike a paradox planetary gear system capable of increasing the speed reduction ratio. Therefore, in a speed reducer with a high speed reduction ratio, it is possible to suppress backlash and suppress a decrease in strength.

B. Variant:
The present invention is not limited to the above-described embodiments, and can be implemented in various aspects without departing from the scope of the invention. For example, the following modifications are possible.

B1. Variant 1:
In the above-described embodiment, the plate-like portion 162, the front step portion 101, and the rear step portion 102 are arranged adjacent to each other along the central axis C. However, the plate portion, the front step portion, and the rear step portion are not necessarily They don't have to be adjacent. For example, it is possible to insert a spacer between at least one of the plate-like portion and the front step portion and between the front step portion and the rear step portion. In addition, when a spacer is used, the frictional resistance between the plate-shaped portion and the front step portion and between the front step portion and the rear step portion can be reduced, and the power transmission efficiency of the speed reducer can be further increased. As a spacer, it is preferable to use a film formed of a lubricious resin film (for example, polytetrafluoroethylene or nylon).

B2. Modification 2:
In the above embodiment, the housing 160 is provided with the plate-like portion 162 to restrict the movement of the input gear 110 and the oscillation driving gear 120 of the front stage portion 101 toward the input side. It is also possible to restrict the movement of the drive gear towards the input side. For example, a bearing is provided between the input shaft fixedly attached to the input gear and the housing to restrict movement along the central axis of the input gear (toward the input side), and the opening is a plate-shaped portion. A plate-like member larger than 162 can also be used to restrict the movement of the swing drive gear toward the input side. Further, by restricting the movement of the input gear toward the input side and providing a flange on at least one of the input gear and the oscillation drive gear, it is possible to restrict the movement of the oscillation drive gear toward the input side.

In general, it is sufficient that the front stage portion having the input gear, the oscillating drive gear and the fixed gear and the rear stage portion having the driven oscillating gear and the output gear are accommodated in the housing. Various means can be used to restrict the movement of the front and rear stages along the central axis so that the front and rear stages are kept in the housing.

B3. Variant 3:
In the above embodiment, the modules of the external gears 111, 121, 141 and the internal gears 129, 139, 159 are all set to be the same, and the difference in the number of teeth between the external gears and the internal gears that mesh with each other is all set to 1. there is However, if the modules of the external and internal gears that mesh with each other are the same, it is possible to change the module for each set of external and internal gears that mesh with each other. In this case, the product of the module of the external gear and the internal gear that mesh with each other and the difference in the number of teeth between the external gear and the internal gear are all set to be the same.

In this way, by setting the product of the module and the difference in the number of teeth to be the same, the oscillating drive gear can be meshed with both the input gear and the fixed gear, and the driven oscillating gear can be meshed with the output gear. . Therefore, the state in which the oscillating drive gear meshes with both the input gear and the fixed gear and the driven oscillating gear and the output gear mesh corresponds to a state in which the product of the module and the tooth number difference is all set to be the same.

Further, as can be seen from the above description, when all modules are set to be the same, the difference in the number of teeth between the internal gear and the external gear that mesh with each other can be arbitrarily changed as long as it is set to be the same. In this case, the number of teeth difference is preferably set to an odd number, more preferably 1. By setting the tooth number difference to an odd number, it is possible to suppress the occurrence of a reverse rotation phenomenon in which the output gear rotates in the opposite direction depending on the rotation state of each gear when the rotation of the input gear is started. Also, if the number of teeth difference is set to 1, the speed reduction ratio can be made higher.

B4. Variant 4:
In the above embodiment, rotational power is input to the input shaft 105 and reduced rotational power is output from the output gear 150, but the input shaft 105 may be omitted. When the input shaft 105 is omitted, for example, the input gear may function as a rotor of a motor, and the input gear may be directly electromagnetically moved to input power to the input gear.

DESCRIPTION OF SYMBOLS 100... Reduction gear 101... Front stage part 102... Rear stage part 105... Input shaft 110... Input gear 111... External gear 120... Oscillation driving gear 121... External gear 129... Internal gear 130... Fixed gear 139... Internal gear 140... Follower oscillation Gears 141 External gear 149 Central hole 150 Output gear 159 Internal gear 160 Housing 161 Tubular portion 162 Plate portion 165 Ear portion 168 Through hole 169 Shaft hole C Central axis

Claims (4)

A reducer,
a housing;
An input gear housed in the housing and to which power to rotate about the rotation shaft of the speed reducer is input, a fixed gear fixed to the housing, and both the input gear and the fixed gear a front stage portion which is a gear mechanism in which meshing oscillating drive gears are arranged in a nested state;
a driven oscillating gear housed in the housing and fixedly attached to the oscillating drive gear; and an output gear that meshes with the driven oscillating gear and outputs reduced power to rotate about the rotation shaft. a rear stage portion which is a gear mechanism arranged in a nested state;
with
The input gear is formed with a first external gear centered on the rotation shaft,
A first internal gear meshing with the first external gear and a second external gear are coaxially formed on the oscillating drive gear,
The fixed gear is formed with a second internal gear meshing with the second external gear and centered on the rotation shaft,
A third external gear coaxial with the first internal gear and the second external gear is formed on the driven oscillating gear,
The output gear is formed with a third internal gear meshing with the third external gear and centered on the rotation shaft,
The modules of the first to third external gears and the first to third internal gears are all set to be the same, and the difference in the number of teeth between the internal gear and the external gear that mesh with each other is all set to be the same. ing,
Decelerator. 2. The speed reducer according to claim 1 , wherein said equal tooth number difference is set to an odd number. 3. The speed reducer according to claim 2 , wherein the same tooth number difference is set to one. 4. The speed reducer according to claim 1 , wherein tooth profiles of said input gear, said oscillating drive gear, said fixed gear, said driven oscillating gear and said output gear are cycloidal tooth profiles.

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