JP2020041653A - Reduction gear - Google Patents

Abstract

To increase a reduction gear ratio and simplify a structure of a reduction gear itself in the reduction gear which can be thinned.SOLUTION: A reduction gear includes a housing, and a pre-stage part and a post-stage part as gear mechanisms housed in the housing. In the pre-stage part, an input gear into which power is input, a fixed gear fixed to the housing, and a swinging and driving gear engaged with both input gear and fixed gear are arranged in a nested state. In the post-stage part, a followup swinging gear fixed to the swinging and driving gear, and an output gear for outputting reduced power are arranged in the nested state. The pre-stage part is constituted so that the swinging and driving gear rotatably swings while the shaft draws a swinging circle around the rotating shaft when the input gear is rotated around the rotating shaft. The pre-stage part is constituted so that the output gear rotates around the rotating shaft when the followup swinging gear rotatably swings while the shaft draws the swinging circle.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a speed reducer for transmitting rotational power at a reduced speed, and more particularly to a speed reducer that can be reduced in thickness.

  A motor is used as a power generation device in a joint driving device for driving a joint of a robot. Generally, the rotation speed of the motor is higher than necessary for a rotation speed suitable for driving the joint. May be. Therefore, in a joint drive device or the like, a speed reducer that reduces the rotational power and transmits the rotational power is usually used. However, when the size of the speed reducer increases, the size of the joint driving device and the like also increases, so that the speed reducer used in a robot or the like is required to be thin. Conventionally, a planetary gear reducer has been used as a reduction gear that can be made thinner, but it has been difficult for a planetary gear reducer to sufficiently increase the reduction ratio.

  Therefore, various speed reducers that can be made thinner and have a sufficiently high reduction ratio have been developed. For example, Patent Literature 1 discloses an internal gear that uses a cylindrical outer pin as a tooth profile, and a curved plate that functions as a planetary gear whose outer periphery is formed as an epitrochoid parallel curve. An inscribed planetary gear mechanism that performs deceleration by letting a cylinder-shaped inner pin be inserted into a circular inner pin hole formed in a curved plate to take out only the decelerated rotation of the curved plate, and a constant-speed internal gear mechanism. A cycloid reducer combining the above two mechanisms is described. In such a cycloid reducer, the difference in the number of teeth between the internal gear and the planetary gear can be reduced, so that the reduction ratio can be increased.

  However, in the cycloid speed reducer, it is necessary to convert the rotational motion into the eccentric swing of the curved plate in the inscribed planetary gear mechanism and take out only the rotation of the curved plate in the constant speed internal gear mechanism. Therefore, it is necessary to provide the cycloid reducer with an eccentric body having a columnar portion eccentric with respect to the center axis of the rotational motion, a carrier fixed with the inner pin protruding, and the like. As described above, the structure of the cycloid reduction gear for realizing the operation as the reduction gear is complicated, and it is difficult to simplify the structure.

JP-A-2006-201996

  Thus, it is difficult to increase the reduction ratio and to simplify the structure of the reduction gear itself in the reduction gear that can be made thin. This problem is not limited to reduction gears used in robots and the like, but is common to reduction gears used in various fields.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-described conventional problems. In a speed reducer that can be reduced in thickness, a technology that increases the reduction ratio and simplifies the structure of the speed reducer itself is provided. The purpose is to provide.

  In order to achieve at least a part of the above objects, the present invention can be realized as the following forms or application examples.

[Application Example 1]
A speed reducer, a housing, an input gear housed in the housing, and inputting power for rotating around a rotation axis of the speed reducer, a fixed gear fixed to the housing, and the input A front stage portion which is a gear mechanism in which a swing drive gear meshing with both the gear and the fixed gear is arranged in a nested state, and a driven swing gear housed in the housing and fixedly attached to the swing drive gear, And a rear part that is a gear mechanism in which an output gear that meshes with the driven rocking gear and outputs reduced power that rotates about the rotation shaft is arranged in a nested state, and the front part is a power mechanism. When the input gear is input to rotate the input gear about the rotation axis, the swing drive gear rotates and swings so that the axis of the swing drive gear draws a swing circle about the rotation axis. Configured as The rear-stage portion, when the driven gear rotates and swings so that the axis of the driven gear coaxial with the swing drive gear draws the swing circle, the output gear is A speed reducer configured to rotate about a rotation axis.

  According to this application example, by appropriately setting the configuration of the gear, the reduction ratio of the reduction gear can be sufficiently increased. According to this application example, the front part and the rear part that realize the deceleration function can be arranged along the rotation axis. The input gear, rocking drive gear and fixed gear of the front stage, and the driven gear and output gear of the rear stage can all be made sufficiently thin, so that the speed reducer is made sufficiently thin. can do. Further, according to this application example, the operation as the speed reducer is realized by the input gear, the swing drive gear, the fixed gear, the slave drive gear, and the output gear. Since these gears can be configured as general gears having an external gear or an internal gear, the structure of the speed reducer itself can be simplified.

[Application Example 2]
The reduction gear according to application example 1, wherein the input gear includes a first external gear having the rotation shaft as an axis, and the swing drive gear includes a first external gear that meshes with the first external gear. And the second external gear are formed coaxially with each other, and the fixed gear is formed with a second internal gear having the rotating shaft as an axis, the second internal gear being engaged with the second external gear. A third external gear coaxial with the first internal gear and the second external gear is formed on the oscillating gear, and the output gear meshes with the third external gear, and the output shaft includes the rotating shaft. A third internal gear serving as an axis is formed, and the first to third external gears and the modules of the first to third internal gears are all set to be the same, and an internal gear and a A reduction gear in which the difference in the number of teeth with the external gear is all set the same.

  According to this application example, since the module is set to be the same for all of the external gear and the internal gear, the input gear, the oscillating drive gear, the fixed gear, the driven oscillating gear, and the output gear constituting the speed reducer can be more easily formed. Can be designed.

[Application Example 3]
The reduction gear according to application example 2, wherein the identically set tooth number difference is set to an odd number.

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

[Application Example 4]
The reduction gear according to application example 3, wherein the identically set tooth number difference is set to one.

  According to this application example, the reduction ratio of the reduction gear can be further increased.

[Application Example 5]
The reduction gear according to any one of application examples 1 to 4, wherein the tooth shapes of the input gear, the swing drive gear, the fixed gear, the driven swing gear, and the output gear are cycloid tooth shapes.

  According to this application example, the backlash of the speed reducer is reduced, and it is easier to increase the speed reduction ratio by reducing the difference in the number of teeth.

  Note that the present invention can be realized in various modes. For example, it can be realized in the form of a speed reducer, a drive mechanism using the speed reducer, a drive device combining the speed reducer and a power generation device such as a motor, and the like.

FIG. 1 is an exploded perspective view showing a configuration of a speed reducer as one embodiment of the present invention. Explanatory drawing which shows operation | movement of a former part. Explanatory drawing which shows operation | movement of a former part. FIG. 9 is an explanatory diagram showing the operation of the subsequent stage. FIG. 9 is an explanatory diagram showing the operation of the subsequent stage.

Hereinafter, embodiments for carrying out the present invention will be described in the following order.
A. Embodiment:
A1. Structure of reduction gear:
A2. Reduction gear operation:
B. Modification:

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

  As shown in FIG. 1, the speed reducer 100 of the present embodiment includes a front part 101 and a rear part 102 which are a combination of gears (gear mechanism) that mesh with each other, an input shaft 105, and a housing 160. The front part 101 is configured by arranging three plate-like gears 110, 120, and 130 having substantially the same thickness in a nested state, and the rear part 102 is configured by two plate-like gears 140 and 140 having substantially the same thickness. 150 are arranged in a nested state. In the following, these five gears 110 to 150 are also referred to as an input gear 110, a swing drive gear 120, a fixed gear 130, a slave swing gear 140, and an output gear 150 in accordance with respective operations and functions described later. Call.

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

  The housing 160 fixed to the outside serves as a reference for operation of each part of the speed reducer 100. Therefore, hereinafter, the operation of each part such as rotation will be described with reference to the housing 160 unless otherwise specified. In addition, the rotation state of each unit 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 housed inside the tubular portion 161 so as to be adjacent to the output side of the plate-shaped portion 162. Further, the driven rocking gear 140 and the output gear 150 that constitute the rear part 102 are housed inside the tubular part 161 so as to be adjacent to the output side of the front part 101.

  As described above, in the speed reducer 100 of the present embodiment, the front part 101 and the rear part 102, which are main components thereof, are arranged along the central axis C in a state of being adjacent to each other. In addition, the five gears 110 to 150 constituting the front part 101 and the rear part 102 can all have sufficiently small thicknesses. Therefore, according to the present embodiment, the reduction gear 100 can be made thinner.

  In addition, as shown in FIG. 1, the inner diameter of the shaft hole 169 provided in the plate-shaped portion 162 is set to be larger than the outer diameter of the input shaft 105 and smaller than the tooth tip circle diameter of the input gear 110. I have. Therefore, the movement of the input gear 110 and the rocking drive gear 120 of the front stage 101 in the input side direction is restricted by the plate-shaped portion 162. Further, the movement of the driven rocking gear 140 and the output gear 150 of the rear part 102 in the input side is restricted by the rocking drive gear 120 and the fixed gear 130 of the front part 101.

  The movement of the input gear 110 and the swing drive gear 120 of the front part 101 and the driven swing gear 140 and the output gear 150 of the rear part 102 in the output direction is restricted by the movement of the movement to the output end of the housing 160. This can be achieved by arranging a member (not shown) that regulates the rotation, 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 columnar member having the central axis C as an axis, and is fixedly attached to the input gear 110 in a state of protruding toward the input side through a shaft hole 169 of the plate-shaped portion 162. By inputting rotational power from a portion of the input shaft 105 protruding to the input side, the input shaft 105 and the input gear 110 rotate about the central axis C.

  The attachment of the input shaft 105 to the input gear 110 is performed, for example, by providing a screw hole having an internal thread on the output end surface of the input shaft 105 and providing a through hole corresponding to the screw hole in the input gear 110. This can be performed by tightening a male screw passing through the through-hole 110 and a female screw of the input shaft 105. Also, it is possible to attach the input shaft 105 to the input gear 110 by providing a shaft fitting hole having substantially the same diameter as the input shaft 105 in the input gear 110 and fitting the input shaft 105 into the shaft fitting hole.

  As shown in FIG. 1, an external gear 111 having six teeth and being coaxial with the center axis C is formed on the input gear 110. In the present embodiment, the tooth profile of the external gear 111 reduces backlash of the speed reducer 100 and reduces the difference in the number of teeth (difference in number of teeth) between the external gear 111 and the internal gear 129 that meshes. To make it easier, it has a cycloid tooth profile. Similarly, in the present embodiment, a cycloid tooth profile is adopted as the tooth profile of the other external gears 121 and 141 and the internal gears 129, 139 and 159 described later.

  However, the external gears 111, 121, 141 and the internal gears 129, 139, 159 do not necessarily need to adopt a cycloidal tooth profile, but may employ a trochoidal tooth profile or an involute tooth profile. It is. In this case, it is possible to adopt a plurality of types of tooth shapes as long as the tooth shapes of the external gear and the internal gear that mesh with each other are the same. However, the point that the backlash is easier to reduce and the point that 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 are easier. Preferably, a tooth profile is employed.

  Further, in the present embodiment, the module (a value obtained by dividing the diameter of the pitch circle by the number of teeth), which is one of the parameters defining the shapes of the external gears 111, 121, 141 and the internal gears 129, 139, 159. Are set identically. As described above, 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 having 18 teeth and being coaxial with the central axis C is formed on the fixed gear 130. The fixed gear 130 is fixedly attached inside the tubular portion 161. The attachment of the fixed gear 130 to the tubular portion 161 (housing 160) is performed by, for example, fitting the fixed gear 130 into the tubular portion 161 or 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. However, the housing may be formed by a method such as shaving, and the fixed gear may be provided on the housing itself. Further, a plate-shaped member having an outer edge portion and a plate-shaped portion corresponding to a cylindrical portion and an ear portion, a plate-shaped member having an outer edge portion and a fixed gear, and a plate-shaped member including only the outer edge portion. May be overlapped in the direction of the central axis C to form a housing. In this case, the housing and the fixed gear fixed to the housing can be manufactured more easily.

  As shown in FIG. 1, an internal gear 129 having seven teeth and an external gear 121 having 17 teeth are formed coaxially on the swing drive gear 120. As described above, the input gear 110, the swing drive gear 120, and the fixed gear 130 are arranged in a nested state. Therefore, the swing drive gear 120 is disposed 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 rocking drive gear 120 and the difference in the number of teeth between the external gear 121 of the rocking drive gear 120 and the internal gear 139 of the fixed gear 130. Are set to 1. Therefore, as described later, the swing drive gear 120 is in a state of meshing with both the input gear 110 and the fixed gear 130, and rotates and swings with the rotation of the input gear 110.

  The driven rocking gear 140 is fixedly attached to the output side of the rocking drive gear 120 so as to be coaxial with the rocking drive gear 120. The attachment of the driven rocking gear 140 to the rocking drive gear 120 is performed, for example, by providing a screw hole having an internal thread on the rocking drive gear 120 and providing a through hole corresponding to the screw hole in the driven rocking gear 140. This can be performed by tightening a male screw passing through the through hole of the swing gear 140 and a female screw of the swing drive gear 120. Further, the swing drive gear 120 and the slave drive gear 140 may be fixed to each other 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 with the rotation rocking of the rocking drive gear 120.

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

  The formation of the center hole 149 provided in the driven rocking gear 140 can be omitted. In this case, since the movement of the input gear in the output side direction is regulated by the driven rocking gear, it is not necessary to separately provide a means for regulating the movement. Therefore, the configuration of the speed reducer can be further simplified.

  The output gear 150 has an outer diameter slightly smaller than the inner diameter of the cylindrical portion 161, and is housed 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 having 17 teeth and being coaxial with the central axis C.

  As described above, in the rear part 102, the difference in the number of teeth between the external gear 141 of the driven rocking gear 140 and the internal gear 159 of the output gear 150 is equal to the difference in the number of teeth between the external gear and the internal gear meshing with each other in the front part 101. The same 1 is set. Therefore, as will be described later, in a state where 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 rocking As a result, the output gear 150 rotates.

  The rotational power transmitted to the output gear 150 can be output by various methods. For example, a plate-shaped member is fixedly attached to the output side of the output gear 150, and a columnar output shaft having a central axis C as an axis is fixedly attached to the output side of the member, and rotational power is output from the output shaft. Can be output. It is also possible to attach an annular member having a gear formed on the output side of the output gear 150, and to output the rotational power from the gear of the member.

A2. Reduction gear operation:
2 and 3 are explanatory diagrams showing the operation of the front section 101 in the speed reducer 100 (FIG. 1) of the present embodiment. 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. Changes. 2 and 3 show the input gear 110, the oscillating drive gear 120, and the fixed gear 130 constituting the front section 101 as 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 swing drive gear 120. The two-dot chain line indicates the respective pitch circles of the external gears 111, 121 and the internal gears 129, 139 formed on the input gear 110, the swing drive gear 120, and the fixed gear 130, and the broken line indicates the center axis C as a center. , The outer gears 111 and 121 and the inner gears 129 and 139 have the same diameter. The black dots drawn on the input gear 110 and the rocking drive gear 120 are drawn to visualize the respective rotation states, and indicate positions fixed on the input gear 110 and the rocking drive gear 120. I have.

  FIG. 2A 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 ± 0 ° in the initial state, and is clockwise (clockwise) when viewed from the output side, that is, a symbol (circled circle) indicating the output side. The direction of the arrow drawn around the symbol with a dot at the center) is a positive value.

  As described above, in the present 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 rocking drive gear 120, and the internal gear 139 of the external gear 121 and the fixed gear 130 of the rocking drive gear 120. Are set to 1 in each case. For this reason, in the initial state shown in FIG. 2A, the swing drive gear 120 is moved downward by half the module from the center axis C (hereinafter, simply referred to as “downward”, etc. Is also eccentric). The external gear 111 of the input gear 110 and the internal gear 129 of the oscillating drive gear 120 mesh with each other at the upper side, which is the direction opposite to the eccentric direction, and the external gear 121 of the oscillating drive gear 120 and the internal gear 139 of the fixed gear 130 engage with each other. Are engaged below the eccentric direction.

  As described above, when the input gear 110 is rotated while the swing drive gear 120 is engaged with the input gear 110, the swing drive gear 120 rotates (rotates) about the axis of the swing drive gear 120 itself. At this time, since the fixed gear 130 meshing with the swing drive gear 120 does not rotate, the axis of the swing drive gear 120 rotates (revolves) around the central axis C as the swing drive gear 120 rotates.

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

  FIG. 3A illustrates a second rotation state (rotation state 2) in which the input gear 110 is further rotated from the first rotation state (FIG. 2B) and the rotation angle of the input gear 110 is + 40 °. Is shown. At this time, the axis of the rocking drive gear 120 rotates from the initial state shown in FIG. 2A by −170 ° around the center axis C, and the rocking drive gear 120 rotates by + 10 ° around the axis. I have. Accordingly, the swing drive gear 120 revolves at a rotation angle of −170 ° and rotates at a rotation angle of + 180 °.

  FIG. 3B illustrates a third rotation state (rotation state 3) in which the input gear 110 is further rotated from the second rotation state (FIG. 3A) and the rotation angle of the input gear 110 is + 60 °. Is shown. At this time, from the initial state shown in FIG. 2A, the axis of the swing drive gear 120 rotates by −255 ° about the center axis C, and the swing drive gear 120 rotates by + 15 ° about the axis. I have. Accordingly, the rocking drive gear 120 revolves at a rotation angle of -255 ° and rotates at a rotation angle of + 270 °.

  As described above, the swing drive gear 120 rotates and swings according to the rotation of the input gear 110 in a state in which both the input gear 110 and the fixed gear 130 mesh with each other. 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 number difference is set to 1, the swing drive gear 120 has, as shown in FIGS. 2 and 3, a circle whose center is the center axis C and whose diameter is equal to the module (a swing circle). Rotate and swing to draw.

  As shown in FIGS. 2 and 3, in the front part 101 of the present embodiment, the rotation direction and the revolving direction of the swing drive gear 120 accompanying the rotation of the input gear 110 are opposite to each other. As described above, since the rotation direction and the revolving direction of the rocking drive gear 120 are opposite to each other, when viewed from a stationary system based on the housing 160 (FIG. 1), the axis of the rocking drive gear 120 is centered. Is smaller than the rotation angle of the input gear 110.

  FIGS. 4 and 5 are explanatory diagrams showing the operation of the rear stage 102 of the speed reducer 100 (FIG. 1) of the present embodiment. FIGS. 4 (a), 4 (b), 5 (a) and 5 (b) show, in this order, the time when rotating power is input to the input shaft 105 and the input gear 110 is rotated. Changes. Note that FIGS. 4 and 5 show the driven gear 140 and the output gear 150 and the input gear 110 that constitute the rear stage 102 as viewed from the output side. The symbols, arrows, markers, two-dot chain lines, broken lines, and black dots drawn in FIG. 4 and FIG. 5 are the same as those in FIG. 2 and FIG.

  FIG. 4A shows an initial state where the rotation angle of the input gear 110 is ± 0 °. As described above, the driven rocking gear 140 is fixedly attached to the output side of the rocking drive gear 120 so as to be coaxial with the rocking drive gear 120. For this reason, in the initial state, the driven rocking gear 140 is eccentric below the central axis C by １ ／ of the module in the initial state. Since the difference in the number of teeth between the external gear 141 of the driven rocking 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 rocking gear 140 and the output gear The 150 internal gear 159 meshes with the lower side, which is the eccentric direction.

  FIG. 4B illustrates a first rotation state (rotation state 1) in which the input gear 110 is rotated in the forward direction from the initial state (FIG. 4A) and the rotation angle of the input gear 110 is + 20 °. Is shown. At this time, similarly to the rocking drive gear 120, the driven rocking gear 140 revolves at a rotation angle of -85 ° and rotates at a rotation angle of 90 °. The external gear 141 of the driven rocking gear 140 and the internal gear 159 of the output gear 150 are in the eccentric direction of the driven rocking gear 140 (that is, the direction rotated −85 ° from the initial state about the center 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. 2B). With the rotation swing of 140, the input gear 110 is decelerated at a high reduction ratio (68 in this embodiment), and rotates in the opposite direction to the input gear 110. Therefore, as shown in FIG. 4B, in the rotation state 1 in which the rotation angle of the input gear 110 is + 20 °, the rotation angle of the output gear 150 is about −0.29 °.

  As shown in FIGS. 5A and 5B, when the input gear 110 is further rotated, the driven rocking gear 140 further rotates and rocks, and the output gear 150 rotates accordingly. In a rotation state 2 where the rotation angle of the input gear 110 is + 40 ° (FIG. 5A), the driven rocking gear 140 revolves at a rotation angle of −170 ° and rotates at a rotation angle of + 180 °. And the rotation angle of the output gear 150 is about -0.58 [deg.]. In a rotation state 3 (FIG. 5B) where the rotation angle of the input gear 110 is + 60 °, the driven rocking gear 140 revolves at a rotation angle of −225 ° and rotates at a rotation angle of + 270 °. And the rotation angle of the output gear 150 is about -0.58 [deg.].

  Note that the reduction ratio (absolute value of the speed transmission ratio) of the reduction gear 100 can be normally calculated using a tabulation method or the like. More specifically, as shown in the following Table 1, 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 state where the whole is glued. Then, the respective rotation speeds of the input gear, the swing drive gear, the fixed gear, the driven swing gear, and the output gear are calculated for the case where the input gear is rotated so as to cancel the rotation of the fixed gear. Next, the number of rotations of each gear in the reduction gear is calculated by adding the number of rotations 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 shows the number of teeth of an external gear, the number of teeth of an internal gear of a fixed gear, the number of teeth of an external gear of a driven rocking gear, and the number of teeth of an internal gear of an output gear.

After calculating the rotation speeds of the respective gears in this way, by dividing the calculated rotation speed of the input gear by the rotation speed of the output gear, a speed transmission ratio j of the entire reduction gear is obtained. The speed transmission ratio j thus obtained is represented by the following equation (1).

Then, as in the reducer 100 of this embodiment, when set to 1 difference in the number of teeth between the gear and the external gear inside which are in mesh with each other, _{namely, Z 21 = Z 1 + 1} , Z 22 = Z 3 -1, Z 4 = If the Z ₅ -1, the transmission ratio j is expressed by the following equation (2).

  In these equations (1) and (2), the speed transmission ratio j is calculated by substituting the respective numbers of teeth of the external gears 111, 121, 141 and the internal gears 129, 139, 159 used in this embodiment. As described above, the speed transmission ratio j is -68. From this, it can be seen that the input rotational power is decelerated at the reduction ratio 68 and the rotational direction is reversed and output.

As can be seen from the above equations (1) and (2), the denominator of equation (1) or equation (2) becomes zero depending on the relationship between the number of teeth, and the transmission ratio j cannot be calculated. In this state, the output gear does not rotate around the central axis even if the driven rocking gear rotates and oscillates so that its axis describes a oscillating circle. Accordingly, when the driven rocking gear rotates and rocks so that its axis describes a rocking circle, the state where the output gear rotates about the central axis is determined by the denominator of the above equations (1) and (2). In a state where the number of teeth does not become zero, that is, Z ₃ Z ₄ -Z ₅ Z ₂₂ for general equation (1), and Z _5- for equation (2) where the number of teeth of the internal gear and the external gear meshing with each other is 1 Z ₃ is equivalent to that non-zero.

  As described above, according to the speed reducer 100 of the present embodiment, it is possible to increase the reduction ratio of the speed reducer 100 while making the speed reducer 100 thinner. Further, in the speed reducer 100 of the present embodiment, a reduction gear function can be realized by a total of five gears of the input gear 110, the swing drive gear 120, the fixed gear 130, the driven swing gear 140, and the output gear 150. Thus, the structure of the reduction gear 100 having a high reduction ratio can be simplified, and its manufacture can be made easier.

  Further, in the speed reducer 100 of the present embodiment, there is no need to use a transposition gear which may cause occurrence of backlash or decrease in strength as in a mysterious planetary gear device capable of increasing the reduction ratio. Therefore, in a speed reducer having a high reduction ratio, it is possible to suppress backlash and to suppress a decrease in strength.

B. Modification:
The present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist of the present invention. For example, the following modifications are possible.

B1. Modification 1
In the above embodiment, the plate-shaped portion 162, the front portion 101, and the rear portion 102 are arranged along the central axis C in a state of being sequentially adjacent to each other, but the plate-shaped portion, the front portion, and the rear portion are not necessarily arranged. It need not be adjacent. For example, it is also possible to interpose a spacer between at least one between the plate-shaped part and the front part and between the front part and the rear part. In the case where the spacer is used, the frictional resistance between the plate-shaped part and the front part and between the front part and the rear part can be reduced, and the power transmission efficiency of the speed reducer can be further increased. It is preferable to use a film formed of a lubricating resin film (for example, polytetrafluoroethylene or nylon) as the spacer.

B2. Modification Example 2:
In the above embodiment, the housing 160 is provided with the plate-shaped portion 162 to restrict the movement of the input gear 110 and the swing drive gear 120 of the front stage 101 in the input side direction. It is also possible to regulate the movement of the drive gear in the input side direction. For example, a bearing is provided between an input shaft fixedly attached to the input gear and the housing to restrict movement (toward the input side) along the central axis of the input gear, and the opening is formed in a plate-like portion. It is also possible to restrict the movement of the swing drive gear in the input side direction by a plate-shaped member larger than 162. In addition, the movement of the input gear in the input side direction can be restricted, and the movement of the rocking drive gear in the input side direction can be restricted by providing a flange on at least one of the input gear and the rocking drive gear.

  Generally, it is sufficient that the front part having the input gear, the oscillating drive gear and the fixed gear, and the rear part having the driven oscillating gear and the output gear are housed in the housing. The regulation of the movement of the front part and the rear part along the central axis can be performed by various means so that the state in which the part and the rear part are housed in the housing is maintained.

B3. Modification 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 gear and the internal gear that mesh with each other is set to one. I have. However, if the module of the external gear and the internal gear that mesh with each other is the same, the module can be changed for each set of the external gear and the internal gear 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 product of 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 all the same, the rocking drive gear can be meshed with both the input gear and the fixed gear, and the driven rocking gear can be meshed with the output gear. . Therefore, the state in which the rocking drive gear meshes with both the input gear and the fixed gear, and the state in which the driven rocking gear meshes with the output gear correspond to a state in which the product of the module and the difference in the number of teeth are all set to be the same.

  Further, as can be understood from the above description, when all the 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 they are set to be the same. In this case, the difference in the number of teeth is preferably set to an odd number, and more preferably to 1. If the difference in the number of teeth is set to an odd number, it is possible to suppress the occurrence of a reverse rotation phenomenon in which the output gear rotates in the reverse direction depending on the rotation state of each gear when the rotation of the input gear is started. If the difference in the number of teeth is set to 1, the reduction ratio can be further increased.

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

DESCRIPTION OF SYMBOLS 100 ... Reduction gear 101 ... Front part 102 ... Rear part 105 ... Input shaft 110 ... Input gear 111 ... External gear 120 ... Swing drive gear 121 ... External gear 129 ... Internal gear 130 ... Fixed gear 139 ... Internal gear 140 ... Follow swing Gear 141 ... External gear 149 ... Center hole 150 ... Output gear 159 ... Internal gear 160 ... Housing 161 ... Cylindrical part 162 ... Plate part 165 ... Rear part 168 ... Through hole 169 ... Shaft hole C ... Center shaft

Claims (5)

A speed reducer,
A housing,
An input gear accommodated in the housing, to which power for rotating about the rotation axis of the speed reducer is input, a fixed gear fixed to the housing, and both the input gear and the fixed gear A front part which is a gear mechanism in which the meshing swing drive gears are arranged in a nested state,
A driven rocking gear housed in the housing and fixedly attached to the rocking drive gear; and an output gear that meshes with the driven rocking gear and outputs reduced power that rotates about the rotation shaft. A rear part which is a gear mechanism in which nests are arranged,
With
When the power is input and the input gear is rotated around the rotation axis, the swing drive gear forms a swing circle around the rotation shaft when the swing drive gear has an axis. It is configured to draw and rotate and swing,
When the driven gear rotates and swings so that the shaft of the driven gear coaxial with the swing drive gear draws the swing circle, the output gear rotates the rotating shaft. Is configured to rotate around the center,
Decelerator. The speed reducer according to claim 1,
A first external gear having the rotation axis as an axis is formed on the input gear,
A first internal gear meshing with the first external gear and a second external gear are coaxially formed on the swing drive gear,
A second internal gear is formed on the fixed gear, the second internal gear meshing with the second external gear, and having the rotation axis as an axis.
A third external gear coaxial with the first internal gear and the second external gear is formed on the driven rocking gear;
A third internal gear meshing with the third external gear and having the rotation shaft as an axis is formed on the output gear;
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 set to be the same. ing,
Decelerator.   The speed reducer according to claim 2, wherein the identically set tooth number difference is set to an odd number.   The speed reducer according to claim 3, wherein the identically set tooth number difference is set to one.   The reduction gear according to any one of claims 1 to 4, wherein the tooth shapes of the input gear, the swing drive gear, the fixed gear, the driven swing gear, and the output gear are cycloid tooth shapes.

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