Planetary gear system and resin molded body

Abstract

To provide a highly convenient planetary gear system and resin molded product. [Solution] The planetary gear system comprises a sun gear, an internal gear surrounding the outer circumference of the sun gear and arranged coaxially with the sun gear, a planetary gear having a protruding planetary shaft portion that meshes with the sun gear and the internal gear and orbits the sun gear while rotating around the planetary shaft portion, and a carrier having a bearing portion that rotatably houses the planetary shaft portion and rotates around the carrier axis to output rotational motion due to the pressing force transmitted from the planetary shaft portion via the bearing portion during the orbit of the planetary gear, wherein the bearing portion is capable of displacing the planetary shaft portion.

Description

Technical Field

[0001] The present invention relates to a planetary gear device and a resin molded body.

Background Art

[0002] A planetary gear device is used as a speed reducer that decelerates and outputs the input rotation, and is used in various mechanical devices such as automobiles and robots.

[0003] In a planetary gear device, the sun gear is connected to the rotation shaft of a drive source such as a motor. Between the sun gear and the internal gear that surrounds the outer circumference of the sun gear and is arranged coaxially with the sun gear, planetary gears that mesh with both are arranged. The planetary gears are supported by a carrier and rotate around the sun gear (also referred to as "revolve") while rotating (also referred to as "rotate") around the planetary shaft portion. The revolving rotation speed (the number of rotations per unit time) of the planetary gears is a speed decelerated at a predetermined ratio (deceleration ratio) with respect to the rotation speed of the rotation input from the drive source to the sun gear. The carrier rotates around the carrier axis as the planetary gears revolve. An output shaft is connected to the carrier at a position on the carrier axis, and the rotational motion of the carrier is output to the outside via the output shaft.

[0004] For example, in the conventional planetary gear device described in Patent Document 1, in the carrier that supports the planetary gears, the opening of the bearing portion that houses the planetary shaft portion not only penetrates the carrier main body portion in the axial direction but also opens to the outside in the carrier radial direction. Therefore, the opening of the bearing portion has a substantially C-shaped opening shape in a plan view in the axial direction. The inner wall of the opening of the bearing portion is configured to contact the outer peripheral surface of the attached planetary shaft portion over a range exceeding 180° (in Patent Document 1, the range obtained by combining the angles α and β each exceeding 90°). That is, the bearing portion holds the attached planetary shaft portion in a non-displaceable manner.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] U.S. Patent No. 11353105 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] As mentioned above, planetary gear systems are used in conjunction with external machinery via output shafts, so robustness is desirable to minimize external influences during operation. Furthermore, from a manufacturing cost perspective, a high degree of flexibility is desirable to adapt to various machinery and installation environments. In other words, there is a demand for highly convenient planetary gear systems.

[0007] The objective of the present invention is to provide a highly convenient planetary gear system and a resin molded body. [Means for solving the problem]

[0008] One embodiment of the planetary gear system according to the present invention is: The sun gear and, An internal gear is arranged around the outer circumference of the aforementioned sun gear and is coaxial with the sun gear, A planetary gear having a protruding planetary shaft portion, meshing with the sun gear and the internal gear, and rotating around the sun gear while rotating around the planetary shaft portion, The carrier has a bearing portion that rotatably houses the planetary shaft portion, and rotates around the carrier axis and outputs rotational motion due to the pressing force transmitted from the planetary shaft portion via the bearing portion during the rotation of the planetary gear, The bearing portion is capable of displacement of the planetary axis portion.

[0009] One embodiment of a resin molded article according to the present invention is: This is a resin molded body used as the carrier in the planetary gear system described above. [Effects of the Invention]

[0010] According to the present invention, the convenience of planetary gear systems can be improved. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is an exploded perspective view of an actuator having a planetary gear system according to one embodiment of the present invention. [Figure 2] Figure 2 is an exploded perspective view of the planetary gear system according to this embodiment. [Figure 3] Figure 3 is an exploded perspective view of the main part of the output-side planetary gear mechanism in the planetary gear device according to this embodiment. [Figure 4] Figure 4 is a diagram illustrating the relationships between the components of the output-side planetary gear mechanism. [Figure 5] Figure 5 is a front perspective view of the output carrier. [Figure 6] Figure 6 is a rear perspective view of the output carrier. [Figure 7] Figure 7 illustrates the external influences on the planetary gear system. [Figure 8] Figure 8 is a diagram illustrating the configuration of the bearing section of the output carrier. [Figure 9] Figure 9 is a diagram illustrating the details of the bearing section of the output carrier. [Figure 10] Figure 10 is a diagram illustrating the relationship between the output shaft connection portion of the output carrier and the outer cylinder portion of the output housing member. [Figure 11] Figure 11 shows the phenomenon where the output shaft is displaced to the positive side in the Y direction. [Figure 12] Figure 12 shows the state in which the carrier's output shaft connection is displaced to the +Y direction according to the phenomenon shown in Figure 11. [Figure 13] Figures 13A-13D are diagrams illustrating the rotational operation of the output-side planetary gear mechanism in the state shown in Figure 12. Figure 13A shows the angular position of the output-side movable part at the first time point, Figure 13B shows the displacement of a specific planetary shaft within a specific bearing section at the first time point, Figure 13C shows the angular position of the output-side movable part at the second time point, and Figure 13D shows the displacement of a specific planetary shaft within a specific bearing section at the second time point. [Figure 14] FIG. 14 is a diagram for explaining an epicyclic gear device according to Modification Example 1, which is a modification example regarding the dimensions of gears in the present embodiment. [Figure 15] FIGS. 15A - 15B are diagrams for explaining an epicyclic gear device according to Modification Example 2, which is a modification example regarding the opening shape of a bearing portion in the present embodiment. FIG. 15A is a diagram showing a state where the bearing portion accommodates a planetary shaft portion having a relatively small diameter, and FIG. 15B is a diagram showing a state where the bearing portion accommodates a planetary shaft portion having a relatively large diameter. [Figure 16] FIGS. 16A - 16B are diagrams for explaining an epicyclic gear device according to Modification Example 3, which is another modification example regarding the opening shape of a bearing portion in the present embodiment. FIG. 16A is a diagram showing a state where the bearing portion accommodates a planetary shaft portion having a relatively small diameter, and FIG. 16B is a diagram showing a state where the bearing portion accommodates a planetary shaft portion having a relatively large diameter. [Figure 17] FIG. 17 is a diagram for explaining an epicyclic gear device according to Modification Example 4, which is yet another modification example regarding the opening shape of a bearing portion in the present embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0012] Hereinafter, an epicyclic gear device according to an embodiment of the present invention will be described with reference to the drawings.

[0013] FIG. 1 is an exploded perspective view of an actuator having an epicyclic gear device according to the present embodiment. FIG. 2 is an exploded perspective view of the epicyclic gear device according to the present embodiment. FIG. 3 is an exploded perspective view of a main part of an output - side epicyclic gear mechanism in the epicyclic gear device according to the present embodiment. FIG. 4 is a diagram for explaining the relationship between components of the output - side epicyclic gear mechanism. FIG. 5 is a front - side perspective view of an output - side carrier. FIG. 6 is a rear - side perspective view of the output - side carrier. FIG. 7 is a diagram for explaining the influence from the outside on the epicyclic gear device. FIG. 8 is a diagram for explaining the configuration of a bearing portion of the output - side carrier. FIG. 9 is a diagram for explaining the details of the bearing portion of the output - side carrier. FIG. 10 is a diagram for explaining the relationship between an output - shaft connection portion of the output - side carrier and an outer cylinder portion of an output - side housing member.

[0014] The following explanation uses a Cartesian coordinate system (X, Y, Z). The Z direction is parallel to the axial direction of each component constituting the planetary gear system 100. For convenience of explanation, in the Z direction, the + (plus) side may be referred to as the front side or output side, and the - (minus) side may be referred to as the rear side or input side. The X direction may also be referred to as the left-right direction, and the Y direction may also be referred to as the up-down direction. Furthermore, the direction extending radially from the axis of each component is called the radial direction, the side approaching the axis of each component in the radial direction is called the inside, and the side moving away from the axis of each component in the radial direction is called the outside. Furthermore, the direction extending in a ring around the axis of each component is called the circumferential direction. When referring to terms such as axial direction, axis, radial direction, or circumferential direction in relation to a specific component, the name of the component in question will be combined with the term. For example, when referring to the axial, center, radial, or circumferential direction of a carrier, the terms "carrier axial direction," "carrier center," "carrier radial direction," or "carrier circumferential direction" are used. When referring to the direction of rotation of each component, the term "direction of rotation" (e.g., "carrier rotation direction") is used in combination with the name of each component. In the following, among the directions of rotation, clockwise direction means that the rotation viewed from the Z+ side is clockwise (right-handed), and counterclockwise direction means that the rotation viewed from the Z+ side is counterclockwise (left-handed).

[0015] In this embodiment, the actuator 1 includes a motor 10, which is an example of a drive source, and a planetary gear system 100. The actuator 1 is used, for example, as an actuator for an electric tailgate used to open and close the tailgate of an automobile. However, the use of the actuator 1 is not limited to this. The motor 10 includes a motor body 11 and a rotating shaft 12. The motor 10 operates under the control of a control unit (not shown) and rotates the rotating shaft 12 to drive the planetary gear system 100. The type of motor 10 is not particularly limited and may be various conventionally known electric motors.

[0016] The planetary gear system 100 reduces the rotation input from the motor 10 at a predetermined reduction ratio and outputs it to the outside. The planetary gear system 100 has a housing 120 and a movable part 140 housed in the housing 120. The housing 120 has an input-side housing member 121 and an output-side housing member 122. The movable part 140 has an input-side movable part 141 and an output-side movable part 142. The input-side movable part 141, together with the internal gear (input-side internal gear) 1211 of the input-side housing member 121, constitutes the input-side planetary gear mechanism 101. The output-side movable part 142, together with the internal gear (output-side internal gear) 1221 of the output-side housing member 122, constitutes the output-side planetary gear mechanism 102.

[0017] Each component of the planetary gear system 100 may be a resin molded body obtained by processing a resin material, for example, by injection molding. However, some parts may be made of resin, while the rest are made of metal. In particular, integrally molding complex components such as the input carrier 1415 or output carrier 1425, which will be described later, using resin material is advantageous because it can significantly reduce the manufacturing cost of the planetary gear system 100.

[0018] The input-side movable part 141 and the output-side movable part 142 are arranged on the input side and output side of each other along the Z direction, and are housed inside a housing 120 which is closed by the input-side housing member 121 and the output-side housing member 122. The input-side planetary gear mechanism 101 reduces the rotation input from the motor 10 at a predetermined reduction ratio and outputs it to the subsequent output-side planetary gear mechanism 102. The output-side planetary gear mechanism 102 reduces the rotation input from the preceding input-side planetary gear mechanism 101 at a predetermined reduction ratio and outputs it to the outside.

[0019] In this embodiment, the planetary gear device 100 includes a two-stage planetary gear mechanism (input-side planetary gear mechanism 101 and output-side planetary gear mechanism 102), but the number of stages in the planetary gear mechanism is not limited to two. The number of stages in the planetary gear mechanism may be only one stage, or it may be three or more stages.

[0020] The input side movable part 141 includes an input side sun gear (not shown), three input side planetary gears 1412 and 1414 (one not shown), and an input side carrier 1415. The input side sun gear is connected to the rotation shaft 12 of the motor 10 and rotates coaxially with the rotation shaft 12. That is, the input side sun gear is directly driven and rotated by the motor 10. The sun teeth formed on the outer circumferential surface of the input side sun gear are, for example, helical teeth cut obliquely with respect to the axial direction of the input side sun gear, so-called helical gears. The three input side planetary gears 1412 and 1414 are arranged at approximately equal intervals in the circumferential direction of the input side sun gear. The three input side planetary gears 1412 and 1414 mesh with both the input side sun gear and the input side internal gear 1211 which is arranged coaxially with respect to the input side sun gear. The teeth formed on the outer circumferential surfaces of the three input planetary gears 1412 and 1414, as well as the teeth formed on the inner circumferential surface of the input internal gear 1211, are so-called helical gears, having, for example, helical teeth cut obliquely with respect to their respective axial directions. The three input planetary gears 1412 and 1414 are each supported so as to be able to rotate on bearing portions 1416 formed on the input carrier 1415. The three input planetary gears 1412 and 1414 revolve around the input sun gear while rotating (rotating) around their own axis (planetary axis portion) based on the rotation of the input sun gear. The input carrier 1415 rotates around its own axis based on the revolution of the three input planetary gears 1412 and 1414. The input carrier 1415 outputs rotational motion to the sun gear (output sun gear) 1421 of the output movable portion 142, which is connected to its output end.

[0021] In this embodiment, the opening shape of the bearing portion 1416 formed on the input carrier 1415 is the same as the opening shape of the bearing portion (first bearing portions 1432, 1433, 1434, second bearing portions 1442, 1443, 1444) formed on the output carrier 1425, which will be described later. Details of the opening shapes of the bearing portions will be described later. However, various conventionally known configurations may be adopted for the configuration of the input planetary gear mechanism 101, including the input carrier 1415.

[0022] The output side movable part 142 includes an output side sun gear 1421, three output side planetary gears 1422, 1423, and 1424, and an output side carrier 1425. As described above, the output side sun gear 1421 is connected to the output side end of the input side carrier 1415 and rotates coaxially with the input side carrier 1415. That is, the output side sun gear 1421 rotates driven by the input side carrier 1415, but it can also be considered to rotate indirectly driven by the motor 10. As one modification, the output side sun gear 1421 may be directly connected to the rotation shaft 12 of the motor 10, in which case the output side sun gear 1421 will rotate directly driven by the motor 10.

[0023] The sun teeth formed on the outer circumferential surface of the output sun gear 1421 are, for example, helical teeth cut obliquely with respect to the axial direction of the output sun gear 1421, so-called helical gears. The teeth formed on the outer circumferential surfaces of the three output planetary gears 1422, 1423, and 1424, as well as the teeth formed on the inner circumferential surface of the output internal gear 1221, are also, for example, helical teeth cut obliquely with respect to their respective axial directions, so-called helical gears.

[0024] The three output planetary gears 1422, 1423, and 1424 are arranged at approximately equal intervals in the circumferential direction of the output sun gear. The three output planetary gears 1422, 1423, and 1424 mesh with both the output sun gear 1421 and the output internal gear 1221, which is arranged coaxially with respect to the output sun gear 1421 (see Figure 4).

[0025] Figure 4 schematically shows the meshing of the teeth. In Figure 4, circle 1421b represents the tooth root of the output sun gear 1421, and circle 1421t represents the tooth tip of the output sun gear 1421. Similarly, circle 1422b represents the tooth root of the output planetary gear 1422, and circle 1422t represents the tooth tip of the output planetary gear 1422. Likewise, circles 1423b and 1424b represent the tooth roots of the output planetary gears 1423 and 1424, respectively, and circles 1423t and 1424t represent the tooth tips of the output planetary gears 1423 and 1424. As shown in Figure 4, the distance between the axes of the output sun gear 1421, which is meshed with the output internal gear 1221, and the output planetary gears 1422, 1423, and 1424 is equal to the radius of the orbital radius O of the output planetary gears 1422, 1423, and 1424 (orbital radius) R1. Also, as shown in Figure 4, a clearance of G1 is left between the outer circumference of the first circular plate portion 1430 and the second circular plate portion 1440 of the output carrier 1425 and the inner circumference (circle 1221t) of the output internal gear 1221.

[0026] The output planetary gear 1422 is supported so as to be able to rotate by having its planetary shaft portion 1422s rotatably housed in first bearing portions 1432 and second bearing portions 1442 formed in the first and second annular plate portions 1430 and 1440, respectively. The output planetary gear 1423 is supported so as to be able to rotate by having its planetary shaft portion 1423s rotatably housed in first bearing portions 1433 and second bearing portions 1443 formed in the first and second annular plate portions 1430 and 1440, respectively. The output planetary gear 1424 is supported so as to be able to rotate by having its planetary shaft portion 1424s rotatably housed in first bearing portions 1434 and second bearing portions 1444 formed in the first and second annular plate portions 1430 and 1440, respectively.

[0027] The output planetary gears 1422, 1423, and 1424 revolve around the output sun gear 1421 while rotating (spinning) around their own axes, i.e., the planetary shafts 1422s, 1423s, and 1424s protruding from them, based on the rotation of the output sun gear 1421. The output carrier 1425 rotates around its own axis based on the revolution of the planetary gears 1422, 1423, and 1424. The output carrier 1425 outputs rotational motion to the outside via the output shaft 2 connected to the output shaft connection part 1427 located at its output end. In this embodiment, the output shaft connection part 1427 is a cylindrical part having knurled teeth on its inner circumferential surface, and the output shaft 2, which has teeth of the corresponding shape on the outer circumferential surface of its rear end, is inserted into the output shaft connection part 1427. The output shaft connection part 1427 is an example of a rotational motion output part.

[0028] The output carrier 1425 has a first circular plate portion 1430 and a second circular plate portion 1440, which are circular plate-like bodies spaced apart in the Z direction. The first circular plate portion 1430 and the second circular plate portion 1440 are connected in a parallel manner by a radial columnar portion 1450 that extends radially in the XY plane and columnarly in the Z direction. The second circular plate portion 1440 is provided with a through hole 1441 through which the output sun gear 1421 is inserted, and an output shaft connection portion 1427 is provided on the output end face of the first circular plate portion 1430. When the output planetary gears 1422, 1423, and 1424 are attached to the output carrier 1425, the first circular plate portion 1430 and the second circular plate portion 1440 are positioned on both sides of the output planetary gears 1422, 1423, and 1424 in the Z direction.

[0029] The first circular plate-shaped portion 1430 and the second circular plate-shaped portion 1440 are each provided with a number of bearing sections equal to the number of output-side planetary gears 1422, 1423, and 1424 at approximately equal angular positions. The bearing sections provided on the first circular plate-shaped portion 1430 are the first bearing sections 1432, 1433, and 1434. The bearing sections provided on the second circular plate-shaped portion 1440 are the second bearing sections 1442, 1443, and 1444. The first bearing sections 1432, 1433, and 1434 and the second bearing sections 1442, 1443, and 1444, which are at the same angular position, have the same opening shape. Specifically, in this embodiment, the openings of the first bearing sections 1432, 1433, 1434 and the second bearing sections 1442, 1443, 1444 not only penetrate the first bearing sections 1432, 1433, 1434 and the second bearing sections 1442, 1443, 1444 in the axial direction, but also open outwards in the radial direction of the output carrier (hereinafter simply referred to as the "carrier radial direction"). Therefore, these openings have a roughly C-shaped opening when viewed in axial plan view. Thus, the output planetary gears 1422, 1423, 1424 can be easily attached from the outside in the carrier radial direction, and can also be easily removed.

[0030] Incidentally, planetary gear systems generally have the problem of being susceptible to external influences via the output shaft 2, since they are connected to the outside via the output shaft 2 (see Figure 7). In particular, if an external force is applied to the output shaft 2 in the vertical or horizontal direction while the planetary gear system 100 is operating, causing axial runout (displacement of the axis) of the output shaft 2, and this axial runout is transmitted to the planetary gear system 100, then abnormal noise is likely to be generated from the planetary gear system 100.

[0031] In this embodiment, the first bearing sections 1432, 1433, 1434 and the second bearing sections 1442, 1443, 1444 are configured to allow displacement of the planetary shaft sections 1422s, 1423s, 1424s, thereby suppressing the generation of abnormal noise even if axial runout of the output shaft 2 occurs during operation.

[0032] Specifically, as shown in Figures 8 and 9, the openings of the first bearing portion 1432 and the second bearing portion 1442 have an extended shape that extends in the radial direction of the carrier. This shape allows the planetary shaft portion 1422s to be displaced in the radial direction of the carrier in the first bearing portion 1432 and the second bearing portion 1442. In this embodiment, the first bearing portion 1432 and the second bearing portion 1442 have a continuous wide shape with a width W greater than or equal to the diameter of the planetary shaft portion 1422s over substantially the entire length in the radial direction of the carrier. Therefore, the range of motion of the planetary shaft portion 1422s can be secured over substantially the entire length in the radial direction of the carrier of the first bearing portion 1432 and the second bearing portion 1442. It is preferable to secure a wide range of motion for the planetary shaft portion 1422s to allow for wide displacement of the planetary shaft portion 1422s, but the range of motion to be secured does not necessarily have to be wide. The extended shape of the openings of the first bearing portion 1432 and the second bearing portion 1442 should be designed according to the tolerance for shaft runout. In the conventional bearing portion described above, the planetary gear is gripped by contacting more than half the outer circumference of the attached planetary shaft portion, so the planetary shaft portion cannot be displaced at all. However, if there is play due to manufacturing tolerances between the bearing portion and the planetary gear, a small displacement of the planetary shaft portion within the bearing portion is permitted. However, such a small displacement is not enough to suppress abnormal noise caused by shaft runout. In this embodiment, in order to suppress abnormal noise caused by shaft runout, the openings of the first bearing portion 1432 and the second bearing portion 1442 are formed in a continuous wide shape with a length L that clearly exceeds the play due to manufacturing tolerances.

[0033] The extended shape described above is any shape that has a width W and length L that allows the planetary axis portion 1422s to move in the radial direction of the carrier. Therefore, it is not necessarily required to be a linear, strip-like shape as in this embodiment, nor is it required to be an oval or elliptical shape. Even if it is a perfect circle, it is possible for the planetary axis portion 1422s to have a width W and length L that allows it to move in the radial direction of the carrier.

[0034] Furthermore, the carrier radial direction to which the planetary axis portion 1422s can be displaced does not necessarily mean the carrier radial direction in the strict sense, passing through the output-side carrier axis CC. Even if the displacement is oblique to such a strict carrier radial direction, if the displacement changes the distance from the output-side carrier axis CC, it can be considered a displacement in the carrier radial direction.

[0035] During operation, the planetary shaft portion 1422s rotates on its own axis due to meshing with the output-side sun gear 1421 and the output-side internal gear 1221, and in this embodiment, it moves clockwise. At this time, the planetary shaft portion 1422s contacts the inner walls of the first bearing portion 1432 and the second bearing portion 1442, applying a pressing force to the inner walls. In this way, the pressing force transmitted from the planetary shaft portion 1422s via the first bearing portion 1432 and the second bearing portion 1442 causes the output-side carrier 1425 to rotate around the output-side carrier axis CC and output its rotational motion. As shown in Figure 9, since the planetary shaft portion 1422s can be displaced over a maximum length L within the first bearing portion 1432 and the second bearing portion 1442, the contact position of the planetary shaft portion 1422s to which the pressing force is transmitted to the first bearing portion 1432 and the second bearing portion 1442 can also be displaced over a maximum length L.

[0036] Here, it is desirable that the spacing G1 shown in Figure 8 is larger than the spacing G2 (see Figure 10) which is left as clearance between the outer circumference of the output shaft connection portion 1427 and the outer cylindrical portion 1222 (an example of a cylindrical portion) surrounding the output shaft connection portion 1427. If spacing G2 is smaller than spacing G1, the first circular plate-shaped portion 1430 of the output-side carrier 1425 is more likely to collide with the inner circumference of the output-side internal gear 1221. In other words, by making spacing G2 larger than spacing G1, it is possible to make it less likely for the first circular plate-shaped portion 1430 to collide with the inner circumference of the output-side internal gear 1221.

[0037] If the spacing G2 is greater than the spacing G1, the output shaft connection portion 1427 contacts the inner circumference of the outer cylinder portion 1222 before the first ring-shaped portion 1430 contacts the inner circumference of the output-side internal gear 1221. At this time, it is preferable that there remains an excess region in which the planetary shaft portion 1422s can be displaced further inward in the radial direction of the carrier than the position of the planetary shaft portion 1422s in the first bearing portion 1432 and the second bearing portion 1442. If the first bearing portion 1432 and the second bearing portion 1442 have an extended shape that includes such an excess region, even if a relatively large axial runout occurs in the output-side carrier 1425, the first bearing portion 1432 and the second bearing portion 1442 will not push the planetary shaft portion 1422s from the inside to the outside. Therefore, the output-side planetary gear 1422 will not be pressed against the output-side internal gear 1221 and stop operating.

[0038] The explanations with reference to Figures 8 and 9 only refer to the planetary shaft portion 1422s of the output planetary gear 1422 and the first bearing portion 1432 and second bearing portion 1442 that house it. However, the output planetary gears 1423 and 1424 have the same dimensions as the output planetary gear 1422, and the first bearing portion 1433 and second bearing portion 1443, as well as the first bearing portion 1434 and second bearing portion 1444, also have the same dimensions as the first bearing portion 1432 and second bearing portion 1442. Therefore, the explanations with reference to Figures 8 and 9 also apply to the relationship between the planetary shaft portion 1423s of the output planetary gear 1423 and the first bearing portion 1433 and second bearing portion 1443, as well as the relationship between the planetary shaft portion 1424s of the output planetary gear 1424 and the first bearing portion 1434 and second bearing portion 1444.

[0039] The rotational operation of the output-side planetary gear mechanism 102 during the axial runout phenomenon, in which the output shaft 2 is displaced to the positive Y-direction, will be described below. Figure 11 shows the axial runout phenomenon when the output shaft 2 is displaced to the positive Y-direction. When the output shaft 2 is displaced to the positive Y-direction, the output shaft connection part 1427 is displaced to the positive Y-direction accordingly, and the position of the output-side carrier axis CC deviates to the positive Y-direction by a distance equal to the gap G2 relative to the position of the output-side sun gear axis SC (see Figure 12).

[0040] At this time, the output carrier 1425 as a whole will be displaced to the positive Y direction, and the first bearing sections 1432, 1433, 1434 and the second bearing sections 1442, 1443, 1444 will also be displaced to the positive Y direction at all angular positions around the output carrier axis CC. Nevertheless, the planetary shaft sections 1422s, 1423s, 1424s can be displaced radially in the carrier direction at the first bearing sections 1432, 1433, 1434 and the second bearing sections 1442, 1443, 1444. Furthermore, while varying the contact positions of the planetary shafts 1422s, 1423s, and 1424s that transmit the pressing force to the first bearing sections 1432, 1433, 1434 and the second bearing sections 1442, 1443, 1444, the planetary shafts 1422s, 1423s, and 1424s can maintain a predetermined orbit O. For example, at the first time point (see Figure 13) when the planetary shaft 1422s is in a position on the Y-direction + side, the planetary shaft 1422s moves relatively inward in the carrier radial direction by the amount by which the first bearing section 1432 and the second bearing section 1442 have been displaced on the Y-direction + side (see Figure 13B). Then, at the second time point (see Figure 13C) when the planetary shaft 1422s has rotated approximately 120° clockwise from the first time point, the planetary shaft 1422s moves relatively outward in the carrier radial direction. In this way, even if the position of the planetary shaft portion 1422s, and consequently the contact position with the first bearing portion 1432 and the second bearing portion 1442, fluctuates with rotational movement, the orbit O of the planetary shaft portion 1422s is maintained. Therefore, the output-side planetary gear mechanism 102 can continue to operate while tolerating axial runout of the output shaft 2. During operation, excessive load is less likely to be placed between the components of the output-side planetary gear mechanism 102, thus suppressing the generation of abnormal noise.

[0041] The following describes some modified examples of this embodiment.

[0042] Modification 1 shown in Figure 14 is a modification relating to the dimensions of the gears. In Modification 1 shown in Figure 14, for example, a sun gear with a larger diameter than the output sun gear 1421 is used. As a result, the distance between the axes of the output planetary gear mechanism 102, i.e., the distance between the planetary shafts 1422s, 1423s, and 1424s from the output sun gear axis SC and the output carrier axis CC (orbital radius R2) is increased compared to the above embodiment (R2 > R1). Nevertheless, the output carrier 1425 can rotatably accommodate the planetary shafts 1422s, 1423s, and 1424s at relatively outer positions in the first bearing sections 1432, 1433, 1434 and the second bearing sections 1442, 1443, 1444. Therefore, the output carrier 1425 can accommodate a variety of distances between axes, thereby improving the design freedom of the planetary gear device. Needless to say, if the distance between the axes (orbital radius) of the output planetary gear mechanism 102 is increased, and the dimensions of the output planetary gears 1422, 1423, and 1424 remain unchanged, then the inner diameter of the output internal gear 1221 needs to be increased.

[0043] Modification 2, shown in Figures 15A and 15B, is a modification relating to the opening shape of the bearing section (representatively the first bearing section 1432 and the second bearing section 1442). In this modification, the first bearing section 1432 and the second bearing section 1442 have an opening shape in which the width increases linearly from the inside to the outside in the radial direction of the carrier. Conversely, the first bearing section 1432 and the second bearing section 1442 have an opening shape in which the width decreases linearly from the outside to the inside in the radial direction of the carrier. With such an opening shape, the length of the movable range of the planetary shaft section 1422s can be adjusted while ensuring the movable range of the planetary shaft section 1422s by changing the diameter of the planetary shaft section 1422s. For example, a planetary shaft portion 1422s with a diameter D1 can be displaced to a position of width W1 (= diameter D1), but if it is replaced with a planetary shaft portion 1422s with a diameter D2 (> diameter D1), the planetary shaft portion 1422s can only be displaced to a position of width W2 (= diameter D2), and as a result the range of motion is shortened from length L1 to length L2. Such adjustment is effective in ensuring the ease of insertion of the output-side sun gear 1421.

[0044] Modification 3, shown in Figures 16A and 16B, is a modification relating to the opening shape of the bearing section (representatively the first bearing section 1432 and the second bearing section 1442), similar to Modification 2. In this modification, the first bearing section 1432 and the second bearing section 1442 have an opening shape in which the width gradually increases from the inside to the outside in the radial direction of the carrier. Conversely, the first bearing section 1432 and the second bearing section 1442 have an opening shape in which the width gradually narrows from the outside to the inside in the radial direction of the carrier. Even with such an opening shape, the length of the movable range of the planetary shaft section 1422s can be adjusted while ensuring the movable range of the planetary shaft section 1422s by changing the diameter of the planetary shaft section 1422s. For example, a planetary axis 1422s with a diameter of D3 can be displaced to a position of width W3 (= diameter D3), but if it is replaced with a planetary axis 1422s with a diameter of D4 (> diameter D3), the planetary axis 1422s can only be displaced to a position of width W4 (= diameter D4), and as a result, the range of motion is shortened from length L3 to length L4.

[0045] Modification 4 shown in Figure 17 is a modification relating to the opening shape of the bearing section (typically the first bearing section 1432 and the second bearing section 1442), similar to modifications 2 and 3. As shown in this modification, a localized restriction may be added to the opening shape to prevent the planetary shaft section 1422s from coming out of the first bearing section 1432 and the second bearing section 1442. In this case, even if the diameter of the restricted section is larger than the width W6, if the diameter D5 of the planetary shaft section 1422s is equal to the width W5 (> width W6), the length L5 of the movable range can be secured.

[0046] As described above, according to this embodiment, the planetary gear system 100 includes an output-side sun gear 1421, an output-side internal gear 1221, output-side planetary gears 1422, 1423, and 1424, and an output-side carrier 1425. The output-side internal gear 1221 surrounds the outer circumference of the output-side sun gear 1421 and is arranged coaxially with the output-side sun gear 1421. The output-side planetary gears 1422, 1423, and 1424 have protruding planetary shaft portions 1422s, 1423s, and 1424s, mesh with the output-side sun gear 1421 and the output-side internal gear 1221, and revolve around the output-side sun gear 1421 while rotating around the planetary shaft portions 1422s, 1423s, and 1424s. The output carrier 1425 has first bearing sections 1432, 1433, 1434 and second bearing sections 1442, 1443, 1444 that rotatably house the planetary shaft sections 1422s, 1423s, 1424s. The output carrier 1425 rotates around the output carrier axis CC and outputs rotational motion due to the pressing force transmitted from the planetary shaft sections 1422s, 1423s, 1424s via the first bearing sections 1432, 1433, 1434 and the second bearing sections 1442, 1443, 1444 while the output planetary gears 1422, 1423, 1424 are orbiting the output carrier. The first bearing sections 1432, 1433, 1434 and the second bearing sections 1442, 1443, 1444 allow for displacement of the planetary shaft sections 1422s, 1423s, 1424s, particularly in the radial direction of the carrier. This allows the planetary gear unit 100 to continue operating while tolerating axial runout of the output shaft 2, and also reduces excessive load between the components of the planetary gear unit 100 during operation, thereby suppressing the generation of abnormal noise. In other words, the planetary gear unit 100 can be made robust, making it less susceptible to external influences during operation.

[0047] Although embodiments of the present invention have been specifically described above, the present invention is not limited to the specific embodiments described above. Various modifications and changes are possible to the specific examples described above within the scope of the gist of the present invention as described in the claims. [Industrial applicability]

[0048] The planetary gear system according to the present invention is useful as a planetary gear system used in various actuators such as back door opening and closing actuators. [Explanation of Symbols]

[0049] 1 Actuator 2 Output shafts 10 motors 11 Motor body 12 Rotation axes 100 Planetary gear system 101 Input side planetary gear mechanism 102 Output side planetary gear mechanism 120 Housing 121 Input side housing member 1211 Input side internal gear 122 Output side housing member 1221 Output side internal gear 1222 Outer cylinder 140 Moving parts 141 Input side movable part 1412, 1414 Input side planetary gear 1415 Input Carrier 1416 Bearing section 142 Output side movable part 1421 Output side sun gear 1422, 1423, 1424 Output side planetary gear 1422s, 1423s, 1424s Planetary axis 1425 Output carrier 1427 Output shaft connection 1430 First circular plate-shaped part 1432, 1433, 1434 First bearing part 1440 Second circular plate-shaped part 1442, 1443, 1444 Second bearing part 1441 Through hole 1450 Radial columnar section CC output side carrier axis G1, G2 interval O orbit R1, R2: Orbital radius (distance between axes) SC output side sun gear axis W, W1, W2, W3, W4, W5, W6 width D, D1, D2, D3, D4, D5 Shaft diameter L, L1, L2, L3, L4, L5 Length

Claims

1. The sun gear and, An internal gear is arranged around the outer circumference of the aforementioned sun gear and is coaxial with the sun gear, A planetary gear having a protruding planetary shaft portion, meshing with the sun gear and the internal gear, and rotating around the sun gear while rotating around the planetary shaft portion, The carrier has a bearing portion that rotatably houses the planetary shaft portion, and rotates around the carrier axis to output rotational motion due to the pressing force transmitted from the planetary shaft portion via the bearing portion during the rotation of the planetary gear, The bearing portion is capable of displacing the planetary shaft portion. Planetary gear system.

2. The bearing portion allows for displacement of the contact position of the planetary shaft portion to which the pressing force is transmitted, in the radial direction of the carrier. The planetary gear apparatus according to claim 1.

3. The bearing portion is such that the displacement of the planetary axis portion is possible in accordance with the displacement of the carrier axis with respect to the axis of the sun gear. A planetary gear system according to claim 1.

4. The bearing portion, when the planetary gear rotates with the carrier axis displaced relative to the axis of the sun gear, causes the contact position of the planetary axis portion to which the pressing force is transmitted to vary in the radial direction of the carrier. The planetary gear apparatus according to claim 3.

5. The bearing portion has an opening that extends in the radial direction of the carrier so as to allow the planetary axis portion to be displaced in the radial direction of the carrier within the opening. The planetary gear apparatus according to claim 1.

6. The bearing portion includes a first bearing portion and a second bearing portion arranged on both sides of the planetary gear in the carrier axial direction, The first bearing portion and the second bearing portion have the same shape as each other. The planetary gear apparatus according to claim 5.

7. The aforementioned shape has a width greater than or equal to the diameter of the planetary axis portion, which is continuous in the radial direction of the carrier. The planetary gear apparatus according to claim 5.

8. The shape is such that the width narrows from the outside to the inside in the radial direction of the carrier. The planetary gear apparatus according to claim 7.

9. The rotational motion output section that defines the carrier axis is further provided with a housing having a cylindrical portion that surrounds it with a clearance in the radial direction of the carrier. The shape includes an excess region in which the planetary axis portion can be displaced inward from the position of the planetary axis portion when the rotational motion output portion contacts the cylindrical portion. The planetary gear apparatus according to claim 7.

10. A resin molded body used as the carrier in the planetary gear system according to claim 1.

Images