Gear device and actuator

Abstract

To improve product efficiency, reduce unevenness in output torque, and maintain motor capacity.SOLUTION: A two-stage deceleration part includes: a fore-stage deceleration part 100 disposed on an input side; and an aft-stage deceleration part disposed on an output side and installed coaxially with the fore-stage deceleration part 100. In a state where the center O1 of a pin groove 141, the center O2 of a pin 150, and a tooth bottom 130a of an external tooth gear 130 are aligned in a straight line, a clearance S1 is formed between the external tooth gear 130 and the pin 150. A first clearance S1 formed in the fore-stage deceleration part 100 is larger than a second clearance formed in the aft-stage deceleration part.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a gear device and an actuator.

Background Art

[0002] In a conventional gear device, in a gear device using an electric motor that electrically drives each actuator from a battery, since an elastic deformation control hole is provided, the elastic deformation in its radial direction is leveled. By leveling the load applied to the outer pins of the external gear in this way, the noise and vibration generated during operation are reduced.

[0003] As such an actuator, for example, as a turning shaft for opening and closing a heavy object, a speed reducer with a high reduction ratio is employed. In a speed reducer with a high reduction ratio, a precision speed reducer is provided coaxially with a motor, and a first speed reducer in the front stage (motor side) and a second speed reducer in the rear stage (output side) are provided in series to achieve a high reduction ratio, and a type that reduces the capacity of the motor with respect to the output torque is known (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In an actuator such as the above Patent Document 1, since a speed reducer is used in two stages, the product efficiency (efficiency of the entire product) deteriorates. In particular, when the input shaft loss and the unevenness of the input torque of the second speed reducer on the output side are large, the speed ratio of the second stage is multiplied, which greatly affects the product efficiency and the unevenness of the output torque. Therefore, there is room for improvement in that regard.

[0006] The present invention provides a gear device and an actuator that can improve product efficiency, reduce unevenness in output torque, and further maintain the motor capacity.

Means for Solving the Problems

[0007] A gear device according to one aspect of the present invention includes an internal gear having a pin groove on its inner circumference, a pin rotatably supported in the pin groove, and an external gear that oscillates and rotates while meshing with the pin. The gear device is provided with a reduction unit that decelerates the rotational driving force of an electric motor from the input side to the output side and transmits it to the rotational driving unit. The reduction unit includes a front-stage reduction unit disposed on the input side and a rear-stage reduction unit disposed on the output side and provided coaxially with the front-stage reduction unit. A gap is formed between the external gear and the pin in a state where the center of the pin groove, the center of the pin, and the bottom of the teeth of the external gear are aligned in a straight line. The first gap formed in the front-stage reduction unit is larger than the second gap formed in the rear-stage reduction unit.

[0008] By configuring in this way, in a state where the center of the pin groove, the center of the pin, and the bottom of the teeth of the external gear in the front-stage reduction unit are aligned in a straight line, by making the first gap formed between the external gear and the pin larger than the second gap of the rear-stage reduction unit, the resistance due to metal contact can be suppressed, and the unevenness in the output torque of the rear-stage reduction unit can be reduced. Therefore, the efficiency of the entire speed reducer can be improved while maintaining the motor capacity. Also, in this case, by reducing the diameter of the pin, it becomes possible to make the first gap larger than the second gap, so that the size of the electric motor can be reduced.

[0009] In the front-stage reduction unit, it is desirable that the radius of curvature of the pin groove is larger than the radius of the pin.

[0010] A gear device according to another aspect of the present invention includes an internal gear having a pin groove on its inner circumference, a pin rotatably supported in the pin groove, and an external gear that swings and rotates while meshing with the pin. The gear device is provided with a reduction unit that decelerates the rotational driving force of an electric motor from the input side to the output side and transmits it to a rotational driving unit. The reduction unit includes a front-stage reduction unit disposed on the input side and a rear-stage reduction unit disposed on the output side and provided coaxially with the front-stage reduction unit. In the backlash formed by the internal gear and the external gear, the backlash formed in the front-stage reduction unit is larger than the backlash formed in the rear-stage reduction unit.

[0011] By configuring in this way, since the backlash formed in the front-stage reduction unit is larger than the backlash formed in the rear-stage reduction unit, the resistance due to metal contact can be suppressed, and the unevenness of the output torque of the rear-stage reduction unit can be reduced. Therefore, the efficiency of the entire speed reducer can be improved while maintaining the motor capacity.

[0012] A case that commonly houses the front-stage reduction unit and the rear-stage reduction unit is provided. When the rotation axis of the electric motor is horizontal, the space in the case is filled with a lubricant, and the filling height of the lubricant is desirably at a position above the central axis of the front-stage reduction unit and at a position where the front-stage reduction unit is not filled.

[0013] A gear device according to another aspect of the present invention includes an internal gear having a pin groove on its inner circumference, a pin rotatably supported in the pin groove, and an external gear that swings and rotates while meshing with the pin. The gear device is provided with a reduction unit that decelerates the rotational driving force of an electric motor from the input side to the output side and transmits it to a rotational driving unit. The reduction unit includes a front-stage reduction unit disposed on the input side and a rear-stage reduction unit disposed on the output side and provided coaxially with the front-stage reduction unit. A gap is formed between the external gear and the pin in a state where the center of the pin groove, the center of the pin, and the bottom of the teeth of the external gear are aligned in a straight line. A first gap formed in the front-stage reduction unit is formed larger than a second gap formed in the rear-stage reduction unit. In the front-stage reduction unit, the radius of curvature of the pin groove is formed larger than the radius of the pin. A case that commonly houses the front-stage reduction unit and the rear-stage reduction unit is provided. When the rotation axis of the electric motor is horizontal, the space in the case is filled with a lubricant, and the filling height of the lubricant is at a position above the central axis of the front-stage reduction unit and at a position where the front-stage reduction unit is not filled.

[0014] By configuring in this way, in a state where the center of the pin groove, the center of the pin, and the bottom of the teeth of the external gear in the front-stage reduction unit are aligned in a straight line, by making the first gap formed between the external gear and the pin larger than the second gap in the rear-stage reduction unit, the resistance due to metal contact can be suppressed, and the unevenness of the output torque of the rear-stage reduction unit can be reduced. Therefore, the efficiency of the entire speed reducer 1 can be improved while maintaining the motor capacity. Also, in this case, by reducing the diameter of the pin, it becomes possible to make the first gap larger than the second gap, so that the size of the electric motor can be reduced. Also, in the front-stage reduction unit, since the radius of curvature of the pin groove is larger than the radius of the pin, the rolling of the pin becomes better, so that the resistance due to metal contact can be more efficiently suppressed, and the unevenness of the output torque of the rear-stage reduction unit can be reduced. Furthermore, when the rotation axis of the electric motor is horizontal, the filling height of the lubricant is at a position above the central axis (rotation center) of the front-stage reduction unit and the front-stage reduction unit is not filled. Therefore, compared with the case where the space in the case is filled with the lubricant, the motor load can be reduced, and torque unevenness in the front-stage reduction unit on the input side can be reduced.

[0015] A gear device according to another aspect of the present invention includes an internal gear having a pin groove on its inner circumference, a pin rotatably supported in the pin groove, and an external gear that meshes with the pin and swings and rotates. The gear device is provided with a reduction unit that decelerates the rotational driving force of an electric motor from the input side to the output side and transmits it to the rotational driving unit. The reduction unit includes a front-stage reduction unit disposed on the input side and a rear-stage reduction unit disposed on the output side and provided coaxially with the front-stage reduction unit. In the backlash formed by the internal gear and the external gear, the backlash formed in the front-stage reduction unit is formed larger than the backlash formed in the rear-stage reduction unit. A case that commonly houses the front-stage reduction unit and the rear-stage reduction unit is provided. When the rotation axis of the electric motor is horizontal, the space in the case is filled with a lubricant, and the filling height of the lubricant is at a position above the central axis of the front-stage reduction unit and the front-stage reduction unit is not filled.

[0016] By configuring in this way, since the backlash formed in the front-stage reduction unit is larger than the backlash formed in the rear-stage reduction unit, the resistance due to metal contact can be suppressed, and torque unevenness of the output torque of the rear-stage reduction unit can be reduced. Therefore, the efficiency of the entire speed reducer can be improved while maintaining the motor capacity. Furthermore, when the rotation axis of the electric motor is horizontal, the filling height of the lubricant is at a position above the central axis (rotation center) of the front-stage reduction unit and the front-stage reduction unit is not filled. Therefore, compared with the case where the space in the case is filled with the lubricant, the motor load can be reduced, and torque unevenness in the front-stage reduction unit on the input side can be reduced.

[0017] A gear device according to another aspect of the present invention includes an internal gear and an external gear that swings and rotates while meshing with the teeth of the internal gear, and is a gear device provided with a reduction unit that decelerates the rotational driving force of an electric motor from the input side to the output side and transmits it to a rotational driving unit. The reduction unit includes a front-stage reduction unit disposed on the input side and a rear-stage reduction unit disposed on the output side and provided coaxially with the front-stage reduction unit. The front-stage reduction unit has a carrier that holds the external gear, and a case that commonly houses the front-stage reduction unit and the rear-stage reduction unit is provided. In the case, a shaft that is the output shaft of the front-stage reduction unit is inserted through an oil seal, and a partition wall that partitions a first space where the front-stage reduction unit is disposed and a second space where the rear-stage reduction unit is disposed is provided. The first space and the second space are each filled with a lubricant, and the inner diameter of the oil seal is smaller than the outer diameter of the carrier.

[0018] By configuring in this way, since the internal space of the speed reducer can be separated into a first space and a second space by the partition wall of the case, the filling amount of the lubricant for each of the front-stage reduction unit and the rear-stage reduction unit can be appropriately managed. That is, it is possible to prevent a problem in which the lubricant leaks out as if the lubricant is 100% filled in each space without depleting the lubricant of the reduction unit in each space. Regardless of the direction of the rotation axis J of the electric motor, the filling height of the lubricant filled in each of the first space and the second space is at least at a position that fills each reduction unit (front-stage reduction unit and rear-stage reduction unit), so the motor load can be reduced and torque unevenness of the front-stage reduction unit on the input side can be reduced. In this case, the usage is not limited to attachment to a horizontal axis with the rotation axis facing horizontally, but attachment to a vertical axis is also possible, and there is no limit to the turning angle of the speed reducer. Further, the structure is not limited to a structure in which the shaft rotates, and a structure in which the case rotates, or a structure in which both rotate may be used, and the usage can be expanded. Furthermore, in this aspect, the inner diameter of the oil seal is smaller than the outer diameter of the carrier, and the contact area of the oil seal can be reduced. Therefore, torque loss of the shaft (shaft) due to the oil seal can be suppressed. As a result, in the speed reducer, unevenness in the output torque of the subsequent-stage speed reduction unit can be reduced. Therefore, the efficiency of the entire speed reducer can be improved while maintaining the motor capacity.

[0019] An actuator according to an aspect of the present invention includes an electric motor, an internal gear having pin grooves on its inner circumference, pins rotatably supported in the pin grooves, and a gear device having an external gear that meshes with the pins and oscillates and rotates. The gear device includes a two-stage speed reduction unit that reduces the rotational driving force of the electric motor from the input side to the output side and transmits it to the rotational driving unit. The two-stage speed reduction unit includes a front-stage speed reduction unit disposed on the input side and a rear-stage speed reduction unit disposed on the output side and provided coaxially with the front-stage speed reduction unit. A gap is formed between the external gear and the pins in a state where the center of the pin grooves, the center of the pins, and the bottom of the teeth of the external gear are aligned in a straight line. A first gap formed in the front-stage speed reduction unit is larger than a second gap formed in the rear-stage speed reduction unit.

[0020] By configuring in this way, by making the first gap formed between the external gear and the pins larger than the second gap of the rear-stage speed reduction unit in a state where the center of the pin grooves, the center of the pins, and the bottom of the teeth of the external gear are aligned in a straight line in the front-stage speed reduction unit, the resistance due to metal contact can be suppressed, and unevenness in the output torque of the rear-stage speed reduction unit can be reduced. Therefore, the efficiency of the entire speed reducer can be improved while maintaining the motor capacity. Also, in this case, since it is possible to make the first gap larger than the second gap by reducing the diameter of the pins, the size of the electric motor can be reduced.

[0021] An actuator according to another aspect of the present invention includes an electric motor, an internal gear having pin grooves on its inner circumference, a pin rotatably supported in the pin grooves, and a gear device having an external gear that meshes with the pin and oscillates and rotates. The gear device includes a two-stage reduction unit that reduces the rotational driving force of the electric motor from the input side to the output side and transmits it to the rotational driving unit. The two-stage reduction unit includes a front-stage reduction unit disposed on the input side and a rear-stage reduction unit disposed on the output side and provided coaxially with the front-stage reduction unit. In the backlash formed by the internal gear and the external gear, the backlash formed in the front-stage reduction unit is larger than the backlash formed in the rear-stage reduction unit.

[0022] By configuring in this way, the backlash formed in the front-stage reduction unit becomes larger than the backlash formed in the rear-stage reduction unit, so that the resistance due to metal contact can be suppressed, and the unevenness of the output torque of the rear-stage reduction unit can be reduced. Therefore, the efficiency of the entire speed reducer can be improved while maintaining the motor capacity.

[0023] An actuator according to another aspect of the present invention includes an electric motor, an internal gear, and a gear device having an external gear that oscillates and rotates while meshing with the teeth of the internal gear. The gear device includes a two-stage reduction unit that reduces the rotational driving force of the electric motor from the input side to the output side and transmits it to the rotational driving unit. The two-stage reduction unit includes a front-stage reduction unit disposed on the input side and a rear-stage reduction unit disposed on the output side and provided coaxially with the front-stage reduction unit. The front-stage reduction unit has a carrier that holds the external gear, and a case that commonly houses the front-stage reduction unit and the rear-stage reduction unit is provided. In the case, a shaft that is the output shaft of the front-stage reduction unit is inserted through an oil seal, and a partition wall that partitions a first space where the front-stage reduction unit is disposed and a second space where the rear-stage reduction unit is disposed is provided. The first space and the second space are each filled with a lubricant, and the inner diameter of the oil seal is smaller than the outer diameter of the carrier.

[0024] By configuring it in this way, since the internal space of the speed reducer can be separated into a first space and a second space by the partition wall of the case, the filling amount of the lubricant for each of the front-stage speed reduction part and the rear-stage speed reduction part can be appropriately managed. That is, it is possible to prevent the problem of lubricant leakage as if the lubricant is 100% filled in each space without depleting the lubricant of the speed reduction part in each space. Regardless of the direction of the rotation axis J of the electric motor, since the filling height of the lubricant filled in each of the first space and the second space is at least at a position that fills each speed reduction part (front-stage speed reduction part and rear-stage speed reduction part), the motor load can be reduced, and torque unevenness of the front-stage speed reduction part on the input side can be reduced. In this case, the usage is not limited to only mounting on a horizontal axis with the rotation axis facing horizontally, but it is also possible to mount on a vertical axis, eliminating the limitation on the turning angle of the speed reducer. Also, the structure is not limited to a structure in which the shaft rotates, and it may be a structure in which the case rotates, or a structure in which both rotate, and the usage can be expanded. Furthermore, in this aspect, the inner diameter of the oil seal becomes smaller than the outer diameter of the carrier, and the contact area of the oil seal can be reduced. Therefore, torque loss of the shaft (shaft) due to the oil seal can be suppressed. As a result, in the speed reducer, unevenness of the output torque of the rear-stage speed reduction part can be reduced. Therefore, the efficiency of the entire speed reducer can be improved while maintaining the motor capacity.

Effects of the Invention

[0025] The above-described gear device and actuator can improve product efficiency, reduce unevenness of output torque, and further maintain the motor capacity.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0027] Next, embodiments of the present invention will be described with reference to the drawings. In the embodiments and modification examples described below, the same reference numerals are given to common parts, and redundant descriptions are partially omitted.

[0028] (First Embodiment) FIG. 1 is a cross-sectional view showing the main part of a speed reducer 1 according to an example of an embodiment of the present invention. FIG. 2 is a perspective view showing a main part of the front-stage speed reduction unit 100 of FIG. 1. FIG. 3 is a plan view of the front-stage speed reduction unit 100 viewed from the axial direction of the rotation axis. FIG. 4 is a cross-sectional view showing a main part of the pin 150 shown in FIG. 3.

[0029] The speed reducer 1 (gear device) is connected to an electric motor 300 and is used as a part of a so-called geared motor. The speed reducer 1 is attached to an actuator having an electric motor 300, such as an arm or a hand of a robot (not shown).

[0030] The speed reducer 1 includes a two-stage speed reduction unit that reduces the rotational driving force of the electric motor 300 from the input side to the output side and transmits it to the rotational driving unit. That is, the speed reducer 1 includes a front-stage speed reduction unit 100 having an internal meshing planetary gear structure, which is arranged on the input side, and a rear-stage speed reduction unit 200 having an internal meshing planetary gear structure, which is arranged on the output side and is provided coaxially with the front-stage speed reduction unit 100 and receives the output of the front-stage speed reduction unit 100.

[0031] Hereinafter, the front-stage speed reduction unit 100 and the rear-stage speed reduction unit 200 will be described in more detail in this order. As shown in FIGS. 1 and 2, the front-stage speed reduction unit 100 and the rear-stage speed reduction unit 200 are housed in a common case 400. The case 400 includes a cylindrical front-stage case portion 410 that covers the front-stage speed reduction unit 100 from the circumferential direction, a cylindrical rear-stage case portion 420 that has a larger diameter than the front-stage case portion 410 and covers the rear-stage speed reduction unit 200 from the circumferential direction, and a connecting portion 430 that connects the rear end of the front-stage case portion 410 and the front end of the rear-stage case portion 420. The front-stage case portion 410, the rear-stage case portion 420, and the connecting portion 430 are provided integrally. The front-stage speed reduction unit 100 is housed in the front-stage case portion 410. The rear-stage speed reduction unit 200 is housed in the rear-stage case portion 420.

[0032] As shown in FIG. 1, in the speed reducer 1, when the rotation axis J of the electric motor 300 is horizontal, the space R in the case 400 is filled with a lubricant 415. The reference sign H shown in FIG. 1 indicates the filling height of the lubricant 415. That is, the filling height H of the lubricant 415 is at a position above the central axis (rotation axis J) of the front-stage speed reduction unit 100 and at a position where the front-stage speed reduction unit 100 is not filled with the lubricant 415. The filling height H of this lubricant 415 is, for example, about 60% of the capacity in the space R in the case 400.

[0033] A connecting portion 112 extends integrally from one end of the input shaft 110 of the front-stage speed reduction unit 100. An insertion hole 114 is formed in the connecting portion 112. The motor shaft 310 of the electric motor 300 is inserted and connected to the insertion hole 114.

[0034] The input shaft 110 is supported by the front-stage case portion 410 and a carrier 172 of a front-stage output shaft 170 ( = rear-stage input shaft 210) described later via a pair of bearings 120. An eccentric body (not shown) is incorporated between the pair of bearings 120. Two external gear wheels 130 are swingably mounted on the outer periphery of this eccentric body via roller bearings. The external gear wheels 130 are internally meshed with an internal gear wheel 140 integrated with the front-stage case portion 410. The internal teeth of the internal gear wheel 140 are formed by a columnar pin 150 that is rotatably supported.

[0035] Each of the two external gear wheels 130 has an internal pin hole formed therethrough, into which an internal pin 132 is inserted. The internal pin 132 can extract the relative rotation component between the external gear wheel 130 and the internal gear wheel 140. The internal pin 132 is fixed to a carrier 172 integrally formed with the front-stage output shaft 170, and is supported in a cantilever state from the carrier 172.

[0036] The front-stage output shaft 170 directly serves as the rear-stage input shaft 210 of the rear-stage speed reduction unit 200.

[0037] On the inner periphery of the front-stage case portion 410, a number of pin grooves 141 having a semi-circular cross-section are formed in the internal gear wheel 140 at its axial center portion. These pin grooves 141 extend in the axial direction and are equidistantly spaced in the circumferential direction, and here they are arranged at a constant pitch.

[0038] As shown in FIG. 3, approximately half of a number (the same number as the pin grooves 141) of columnar pins 150 are inserted into the pin grooves 141 and are rotatably supported. Thereby, the pins 150 are provided on the inner periphery of the front-stage case portion 410 at equal distances (by a constant pitch) in the circumferential direction. Here, the aforementioned constant pitch is the value obtained by dividing the circumferential length of an imaginary center circle passing through the centers of all the pins 150 by the number of pins 150. In other words, it is the arc length when the centers of any two adjacent pins 150 are connected by an arc segment.

[0039] As shown in FIG. 1, a plurality (here, two) of ring-shaped external gear wheels 130 are axially arranged and housed within the internal gear wheel 140. A number of external teeth 131 having a trochoid tooth profile, specifically a peritrochoid tooth profile, are respectively formed on the outer peripheries of these external gear wheels 130. The external gear wheels 130 swing and rotate while their external teeth 131 mesh with the pins 150.

[0040] And the number of teeth of the external teeth 131 of the external gear 130 is one less than the number of teeth of the pin 150 (the tooth number difference is 1). The reason for setting the tooth number difference between the pin 150 and the external teeth 131 to 1 is that, compared with the case where the tooth number difference between them is a value of 2 or more, a high reduction ratio can be achieved and the processing cost can be reduced.

[0041] As shown in FIG. 1, in the front-stage reduction unit 100, a carrier 172 in the shape of an end plate is provided. A pair of external gears 130 are rotatably held by inner pins 132 on the carrier 172. Then, when the electric motor 300 operates and the external gear 130 performs eccentric swing rotation. At this time, as shown in FIG. 3, at the contact points between the external teeth 131 and the pins 150 that mesh with each other, driving component forces in the direction of the action line N are respectively applied from the external teeth 131 to the corresponding pins 150, and as a reaction thereto, reaction forces K of the driving component forces in the direction of the action line N are respectively applied from the pins 150 to the external teeth 131.

[0042] As shown in FIGS. 3 and 4, in the front-stage reduction unit 100, with the center O1 of the pin groove 141, the center O2 of the pin 150, and the tooth root 130a of the external gear 130 aligned in a straight line, a gap S1 is formed between the external gear 130 and the pin 150. The reference symbol X in FIG. 4 indicates the straight line connecting the center O1 of the pin groove 141, the center O2 of the pin 150, and the tooth root 130a of the external gear 130. The first gap S1 formed in the front-stage reduction unit 100 is set to be larger than the second gap S2 (see FIG. 1) formed in the rear-stage reduction unit 200. For example, it can be realized by making the outer diameter of the pin 150 smaller than the outer diameter set in the state where the above-mentioned gap S1 is absent (zero). Note that this gap S1 varies depending on the reduction gear 1 adopted and the diameter dimension of the pin.

[0043] Also, as shown in FIG. 4, in the front-stage reduction unit 100, the radius of curvature R1 of the pin groove 141 is set to be larger than the radius R2 of the pin 150. That is, when the pin 150 meshes with the pin groove 141, the center O2 of the pin 150 is located on the outer peripheral side of the center O1 of the pin groove 141.

[0044] Here, in FIG. 3, reference numeral K indicates the reaction force applied to the external teeth 131, and reference numeral N indicates the line of action. The line of action N of each reaction force K is located on a line perpendicular to the tooth surface at the contact point between the external teeth 131 and the pin 150. However, since the plurality of lines of action N are such that the pin 150 has a cylindrical shape and the external teeth 131 are formed of a trochoidal tooth profile as described above, they converge (intersect) at a point on the external gear 130, that is, the convergence point C. Then, the sum of the tangential direction components of the driving component force is applied to the internal gear 140 as a rotational driving force.

[0045] As shown in FIG. 1, the rear-stage input shaft 210 is supported by first and second output flanges 266 and 268, which will be described later, via a pair of tapered roller bearings 220. An eccentric body 224 is incorporated between the pair of tapered roller bearings 220, 220. Two external gears 230 and 232 are mounted on the outer periphery of the eccentric body 224 via roller bearings. The external gears 230 and 232 are internally meshed with an internal gear 240 integrated with the rear-stage case portion 420. The internal teeth of the internal gear 240 are formed by a cylindrical external pin 242 that is rotatably supported.

[0046] A highly accurate eccentric internal pin 260 is inserted into the two external gears 230 and 232. The eccentric internal pin 260 is supported at both ends via bearings 270 and 272 by a pair of disk-shaped first and second output flanges 266 and 268 arranged on both sides of the external gears 230 and 232. The first and second output flanges 266 and 268 are rotatably supported by the rear-stage case portion 420 via bearings 270 and 272, respectively.

[0047] Note that in the backlash formed by the internal gear and the external gear in the speed reducer 1 according to the present embodiment, the backlash formed in the front-stage reduction portion 100 is formed larger than the backlash formed in the rear-stage reduction portion 200.

[0048] As described above, the speed reducer 1 of the present embodiment includes an internal gear 140 having a pin groove 141 on its inner circumference, a pin 150 rotatably supported in the pin groove 141, and an external gear 130 that swings and rotates while the external teeth 131 mesh with the pin 150, and is provided with a two-stage reduction unit that reduces the rotational driving force of the electric motor 300 from the input side to the output side and transmits it to the rotational driving unit. The two-stage reduction unit includes a front-stage reduction unit 100 disposed on the input side and a rear-stage reduction unit 200 disposed on the output side and provided coaxially with the front-stage reduction unit 100. A gap S1 is formed between the external gear 130 and the pin 150 in a state where the center O1 of the pin groove 141, the center O2 of the pin 150, and the bottom 130a of the teeth of the external gear 130 are aligned in a straight line. The first gap S1 formed in the front-stage reduction unit 100 is larger than the second gap S2 formed in the rear-stage reduction unit 200.

[0049] By configuring in this way, in a state where the center O1 of the pin groove 141, the center O2 of the pin 150, and the bottom 130a of the teeth of the external gear 130 in the front-stage reduction unit 100 are aligned in a straight line, by making the first gap S1 formed between the external gear 130 and the pin 150 larger than the second gap S2 of the rear-stage reduction unit 200, the resistance due to metal contact can be suppressed, and the unevenness of the output torque of the rear-stage reduction unit 200 can be reduced. Therefore, the efficiency of the entire speed reducer 1 can be improved while maintaining the motor capacity. Thus, in the present embodiment, by reducing the diameter of the pin 150, it becomes possible to make the first gap S1 larger than the second gap S2, so that the electric motor 300 can be downsized.

[0050] In the speed reducer 1 of the present embodiment, in the front-stage reduction unit 100, the radius of curvature R1 of the pin groove 141 is larger than the radius R2 of the pin 150. For this reason, since the rolling of the pin 150 becomes even better, the resistance due to metal contact can be suppressed more efficiently, and the unevenness of the output torque of the rear-stage reduction unit 200 can be reduced.

[0051] Furthermore, in the speed reducer 1 of the present embodiment, a case 400 that commonly houses the front-stage speed reduction unit 100 and the rear-stage speed reduction unit 200 is provided. When the rotation axis of the electric motor 300 is horizontal, the space R in the case 400 is filled with a lubricant 415. The filling height H of the lubricant 415 is at a position above the central axis (rotation axis J) of the front-stage speed reduction unit 100 and at a position where the front-stage speed reduction unit 100 is not filled. Therefore, in the front-stage speed reduction unit 100, since the lubricant 415 is not filled, the motor load can be reduced compared to the case where the space R in the case 400 is filled with the lubricant 415, and torque unevenness in the front-stage speed reduction unit 100 on the input side can be reduced.

[0052] (Second Embodiment) As shown in FIG. 5, the speed reducer 1A (gear device) of the second embodiment includes a two-stage speed reduction unit that decelerates the rotational driving force of an electric motor (not shown, see FIG. 1) from the input side to the output side and transmits it to the rotational driving unit. The two-stage speed reduction unit includes a front-stage speed reduction unit 100A disposed on the input side and a rear-stage speed reduction unit 200A disposed on the output side and provided coaxially with the front-stage speed reduction unit 100A. In this embodiment, it is also possible to omit the electric motor.

[0053] The front-stage speed reduction unit 100A includes an internal gear 140 and an external gear 130 that swings and rotates while meshing with the teeth of the internal gear 140. The front-stage speed reduction unit 100A has a carrier 172 that holds the external gear 130. The carrier 172 has a shaft 173 that is coaxial with the rotation axis J on the output side in the axial direction. The shaft 173 corresponds to the output shaft of the front-stage speed reduction unit 100A. The shaft 173 protrudes from the front surface 172a of the carrier 172 to the output side. The shaft 173 is provided integrally with the carrier 172, but it may be divided.

[0054] The speed reducer 1A is provided with a case 400A that commonly houses the front-stage speed reduction unit 100A and the rear-stage speed reduction unit 200A. The case 400A includes a cylindrical front-stage case portion 410A that covers the front-stage speed reduction unit 100A from the circumferential direction, a cylindrical rear-stage case portion 420A that has a larger diameter than the front-stage case portion 410A and covers the rear-stage speed reduction unit 200A from the circumferential direction, and a connecting portion 430A that connects the rear end of the front-stage case portion 410A and the front end of the rear-stage case portion 420A.

[0055] A partition wall 440A is provided in the case 400A to insert the shaft 173, which is the output shaft of the front-stage speed reduction unit 100A, through an oil seal 500, and to partition a first space K1 where the front-stage speed reduction unit 100A is disposed and a second space K2 where the rear-stage speed reduction unit 200A is disposed. The front-stage case portion 410A, the rear-stage case portion 420A, the connecting portion 430A, and the partition wall 440A are integrally provided. Note that the partition wall 440A may be divided with respect to other portions (the front-stage case portion 410A, the rear-stage case portion 420A, and the connecting portion 430A) of the case 400A. The front-stage speed reduction unit 100A is housed in the front-stage case portion 410A. The rear-stage speed reduction unit 200A is housed in the rear-stage case portion 420A.

[0056] The partition wall 440A has a through-hole 441 coaxial with the rotation axis J at the center. The shaft 173 is inserted through the through-hole 441. An oil seal 500 is disposed between the through-hole 441 and the shaft 173. The inner diameter of the oil seal 500 is smaller than the outer diameter of the carrier 172.

[0057] The first space K1 and the second space K2 are each filled with a lubricant 415. The lubricant 415 can be filled in each of the spaces of the first space K1 and the second space K2 in an appropriate enclosed amount. In the first space K1 and the second space K2, for example, it can be made 60 to 80% respectively. In this way, since the spaces K1 and K2 are partitioned from each other and independent, and the enclosed level of the lubricant 415 is constant, the orientation of the speed reducer 1A can be set arbitrarily. In FIG. 5, the reference sign H1 indicates the filling level (filling height) of the lubricant 415 in the first space K1, and the reference sign H2 indicates the filling level (filling height) of the lubricant 415 in the second space K2.

[0058] In the speed reducer 1A according to the second embodiment, in the case 400A, the shaft 173, which is the output shaft of the front-stage speed reduction unit 100A, is inserted through the oil seal 500, and a partition wall 440A is provided to partition the first space K1 where the front-stage speed reduction unit 100A is disposed and the second space K2 where the rear-stage speed reduction unit 200A is disposed. The first space K1 and the second space are filled with a lubricant 415, respectively. The inner diameter of the oil seal 500 is smaller than the outer diameter of the carrier 172.

[0059] Therefore, since the internal space of the speed reducer 1A can be separated into the first space K1 and the second space K2 by the partition wall 440A of the case 400A, the filling amounts of the lubricants 415 of the front-stage speed reduction unit 100A and the rear-stage speed reduction unit 200A can be appropriately managed. That is, it is possible to prevent a problem that the lubricant 415 leaks out as if the lubricant 415 is 100% filled in each of the spaces K1 and K2 without depleting the lubricants 415 of the speed reduction units 100A and 200A in each of the spaces K1 and K2. Regardless of the direction of the rotation axis J of the electric motor, the filling height of the lubricant 415 filled in each of the first space K1 and the second space K2 is at least at a position that fills each of the speed reduction units (the front-stage speed reduction unit 100A and the rear-stage speed reduction unit 200A), so that the motor load can be reduced and torque unevenness of the front-stage speed reduction unit 100A on the input side can be reduced.

[0060] Thus, in the speed reducer 1A according to the present embodiment, not only can it be attached to a horizontal axis with the rotation axis J oriented horizontally but also it can be attached to a vertical axis, and there is no limitation on the turning angle of the speed reducer 1A. Further, it is not limited to the structure in which the shaft 173 rotates as in the present embodiment, and the structure may be such that the case 400A rotates or both rotate, and the usage applications can be expanded.

[0061] Further, in the present embodiment, the inner diameter of the oil seal 500 is smaller than the outer diameter of the carrier 172, and the contact area of the oil seal 500 can be reduced. Therefore, the torque loss of the shaft (shaft 713) due to the oil seal 500 can be suppressed.

[0062] Thus, in the speed reducer 1A according to the present embodiment, unevenness in the output torque of the subsequent-stage speed reduction unit 200A can be reduced. Therefore, the efficiency of the entire speed reducer can be improved while maintaining the motor capacity.

[0063] Note that the present invention is not limited to the above-described embodiment, and various design changes are possible without departing from the gist thereof. For example, in the above-described embodiment, in the front-stage speed reduction unit 100, the radius of curvature R1 of the pin groove 141 is set to be larger than the radius R2 of the pin 150, but the present invention is not limited to such a configuration.

[0064] Further, in the present embodiment, a case 400 that commonly houses the front-stage speed reduction unit 100 and the subsequent-stage speed reduction unit 200 is provided. When the rotation axis of the electric motor 300 is horizontal, the space in the case 400 is filled with a lubricant 415, and the filling height H of the lubricant 415 is at a position above the central axis of the front-stage speed reduction unit 100 and at a position where the front-stage speed reduction unit 100 is not filled, but the present invention is not limited to such a filling height H.

[0065] Further, in the present embodiment, a gap is formed between the external gear and the pin in a state where the center of the pin groove, the center of the pin, and the bottom of the tooth of the external gear are aligned in a straight line, and the first gap formed in the front-stage speed reduction unit is made larger than the second gap formed in the subsequent-stage speed reduction unit. However, a gap may be formed between the external gear and the pin in a state where the center of the pin groove, the center of the pin, and the tip of the tooth of the external gear are aligned in a straight line. Regarding the tip of the tooth of the external gear, a gap may be provided between the tip of the tooth and the pin by modifying the tooth profile or the like.

[0066] Further, as the speed reducer 1, in the present embodiment, an epicyclic gear mechanism is shown as an example, but the present invention is not limited to an epicyclic gear mechanism.

Explanation of Reference Numerals

[0067] 1, 1A... Reducer (gear device), 100, 100A... Front-stage reduction part, 110... Input shaft, 130... External gear, 130a... Tooth bottom, 131... External teeth, 140... Internal gear, 141... Pin groove, 150... Pin, 170... Front-stage output shaft, 200, 200A... Rear-stage reduction part, 210... Rear-stage input shaft, 300... Electric motor, 400, 400A... Case, 410, 410A... Front-stage case part, 415... Lubricant, 420, 420A... Rear-stage case part, 440A... Partition wall, 500... Oil seal, J... Axis of rotation, K1... First space, K2... Second space, O1... Center of the pin groove, O2... Center of the pin, S1... First gap, S2... Second gap

Claims

1. an internal gear having a pin groove on an inner circumference; A pin rotatably supported in the pin groove; an external gear that oscillates and rotates while its external teeth are meshed with the pin, A gear device including a reduction gear unit that reduces the rotational drive force of an electric motor from an input side to an output side and transmits the reduced speed to a rotational drive unit, The speed reducing portion is A front-stage reduction unit disposed on the input side; a rear-stage reduction section disposed on an output side and coaxially arranged with the front-stage reduction section, a gap is formed between the external gear and the pin in a state in which the center of the pin groove, the center of the pin, and the tooth bottom of the external gear are aligned in a straight line; A gear device, wherein a first gap formed in the front-stage reduction section is larger than a second gap formed in the rear-stage reduction section.

2. The gear device according to claim 1 , wherein in the front-stage reduction section, a radius of curvature of the pin groove is larger than a radius of the pin.

3. an internal gear having a pin groove on an inner circumference; A pin rotatably supported in the pin groove; an external gear that oscillates and rotates while its external teeth are meshed with the pin, A gear device including a reduction gear unit that reduces the rotational drive force of an electric motor from an input side to an output side and transmits the reduced speed to a rotational drive unit, The speed reducing portion is A front-stage reduction unit disposed on the input side; a rear-stage reduction section disposed on an output side and coaxially arranged with the front-stage reduction section, a backlash formed in the front-stage reduction section between the internal gear and the external gear is larger than a backlash formed in the rear-stage reduction section.

4. a case is provided that commonly houses the front-stage reduction unit and the rear-stage reduction unit, When the rotation axis of the electric motor is horizontal, the space within the case is filled with a lubricant, 4. The gear device according to claim 1, wherein the lubricant is filled at a height above a central axis of the front-stage reduction section and at a position where the front-stage reduction section is not filled.

5. an internal gear having a pin groove on an inner circumference; A pin rotatably supported in the pin groove; an external gear that oscillates and rotates while its external teeth are meshed with the pin, A gear device including a reduction gear unit that reduces the rotational drive force of an electric motor from an input side to an output side and transmits the reduced speed to a rotational drive unit, The speed reducing portion is A front-stage reduction unit disposed on the input side; a rear-stage reduction section disposed on an output side and coaxially arranged with the front-stage reduction section, a gap is formed between the external gear and the pin in a state in which the center of the pin groove, the center of the pin, and the tooth bottom of the external gear are aligned in a straight line; a first gap formed in the front-stage reduction section is larger than a second gap formed in the rear-stage reduction section, In the front-stage reduction section, a curvature radius of the pin groove is formed larger than a radius of the pin, a case is provided that commonly houses the front-stage reduction unit and the rear-stage reduction unit, When the rotation axis of the electric motor is horizontal, the space within the case is filled with a lubricant, A gear device, wherein the lubricant filling height is a position above a central axis of the front-stage reduction section and a position where the front-stage reduction section is not filled.

6. an internal gear having a pin groove on an inner circumference; A pin rotatably supported in the pin groove; an external gear that oscillates and rotates while its external teeth are meshed with the pin, A gear device including a reduction gear unit that reduces the rotational drive force of an electric motor from an input side to an output side and transmits the reduced speed to a rotational drive unit, The speed reducing portion is A front-stage reduction unit disposed on the input side; a rear-stage reduction section disposed on an output side and coaxially arranged with the front-stage reduction section, In the backlash formed by the internal gear and the external gear, the backlash formed in the front-stage reduction section is formed larger than the backlash formed in the rear-stage reduction section, a case is provided that commonly houses the front-stage reduction unit and the rear-stage reduction unit, When the rotation axis of the electric motor is horizontal, the space within the case is filled with a lubricant, A gear device, wherein the lubricant filling height is a position above a central axis of the front-stage reduction section and a position where the front-stage reduction section is not filled.

7. The gear has an internal gear and an external gear that oscillates and rotates while the teeth of the internal gear mesh with each other, A gear device including a reduction gear unit that reduces the rotational drive force of an electric motor from an input side to an output side and transmits the reduced speed to a rotational drive unit, The speed reducing portion is A front-stage reduction unit disposed on the input side; a rear-stage reduction section disposed on an output side and coaxially arranged with the front-stage reduction section, the front-stage reduction unit has a carrier that holds the external gear, a case is provided that commonly houses the front-stage reduction unit and the rear-stage reduction unit, the case is provided with a partition wall through which a shaft that is an output shaft of the front-stage reduction unit is inserted via an oil seal, the partition wall separating a first space in which the front-stage reduction unit is disposed and a second space in which the rear-stage reduction unit is disposed; The first space and the second space are each filled with a lubricant, an inner diameter of the oil seal being smaller than an outer diameter of the carrier;

8. An electric motor; an internal gear having a pin groove on an inner circumference; A pin rotatably supported in the pin groove; and a gear device having an external gear that oscillates and rotates while its external teeth are meshed with the pin, The gear device comprises: a two-stage reduction gear unit that reduces the rotational drive force of the electric motor from the input side to the output side and transmits it to a rotation drive unit, the two-stage reduction unit includes a front-stage reduction unit arranged on an input side, and a rear-stage reduction unit arranged on an output side and coaxially with the front-stage reduction unit, a gap is formed between the external gear and the pin in a state in which the center of the pin groove, the center of the pin, and the tooth bottom of the external gear are aligned in a straight line; An actuator, wherein a first gap formed in the front-stage reduction section is larger than a second gap formed in the rear-stage reduction section.

9. An electric motor; an internal gear having a pin groove on an inner circumference; A pin rotatably supported in the pin groove; and a gear device having an external gear that oscillates and rotates while its external teeth are meshed with the pin, The gear device comprises: a two-stage reduction gear unit that reduces the rotational drive force of the electric motor from the input side to the output side and transmits it to a rotation drive unit, the two-stage reduction unit includes a front-stage reduction unit arranged on an input side, and a rear-stage reduction unit arranged on an output side and coaxially with the front-stage reduction unit, an actuator, wherein a backlash formed in the front-stage reduction section between the internal gear and the external gear is larger than a backlash formed in the rear-stage reduction section.

10. An electric motor; An actuator including a gear device having an internal gear and an external gear that oscillates and rotates while meshing with the teeth of the internal gear, The gear device comprises: a two-stage reduction gear unit that reduces the rotational drive force of the electric motor from the input side to the output side and transmits it to a rotation drive unit, The two-stage reduction unit includes: a front-stage reduction section disposed on an input side, and a rear-stage reduction section disposed on an output side and coaxially arranged with the front-stage reduction section, the front-stage reduction unit has a carrier that holds the external gear, a case is provided that commonly houses the front-stage reduction unit and the rear-stage reduction unit, the case is provided with a partition wall through which a shaft that is an output shaft of the front-stage reduction unit is inserted via an oil seal, the partition wall separating a first space in which the front-stage reduction unit is disposed and a second space in which the rear-stage reduction unit is disposed; The first space and the second space are each filled with a lubricant, The actuator, wherein an inner diameter of the oil seal is smaller than an outer diameter of the carrier.

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