Differential gear reducer

Abstract

To provide a differential gear reducer having high transmission efficiency of rotational power.SOLUTION: The planetary gear device includes a planetary gear 1 that rotates eccentrically, an internal gear 2 having a gear that meshes with the planetary gear, a carrier support plate 11 and an output flange 12 that are disposed to face each other with the planetary gear interposed therebetween and are fastened by a carrier pin 13 penetrating the planetary gear, and an output pin 14 that transmits eccentric rotation of the planetary gear to the output flange. The planet, the carrier support plate and the output flange have output pin insertion holes 3, 4, 5 into which the output pins are inserted, and the opening diameter of the output pin insertion holes is set to be equal to or larger than the sum of the eccentric amount when the planet is eccentrically rotated and the outer diameter of the output pins.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a differential gear reducer. [Background technology]

[0002] A differential gear reducer using a roller mechanism is known as a reducer that can achieve a high reduction ratio. A conventional differential gear reducer disclosed in Patent Document 1 includes internal gears, planetary gears that mesh with the internal gears so as to be eccentrically rotatable, and output pins that are inserted into a plurality of pin holes formed in the planetary gears and that transmit and receive rotational power to and from the planetary gears, with resin bushings provided between the output pins and the inner surfaces of the pin holes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-214834 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional differential gear reducers, a resin bushing is provided between the output pin and the inner peripheral surface of the pin through hole, and this resin bushing transmits the rotational power of the planetary gear while sliding against the output pin. As a result, conventional differential gear reducers have the problem of large losses due to sliding and low rotational power transmission efficiency.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a differential gear reducer with high rotational power transmission efficiency. [Means for solving the problem]

[0006] The differential gear reducer of the present disclosure comprises eccentrically rotating planets, internal teeth having gears that mesh with the planets, a carrier support plate and an output flange arranged opposite each other with the planets in between and fastened by carrier pins that pass through the planets, and an output pin that transmits the eccentric rotation of the planets to the output flange, the opening diameter of the carrier pin through holes provided on the planets and through which the carrier pins pass is set to be larger than the sum of the amount of eccentricity when the planets eccentrically rotate and the outer diameter of the carrier pins, and the planets, carrier support plate, and output flange have output pin insertion holes into which the output pins are inserted, the opening diameter of the output pin insertion holes being set to be larger than the sum of the amount of eccentricity when the planets eccentrically rotate and the outer diameter of the output pins. [Effects of the Invention]

[0007] In the differential gear reducer of the present disclosure, the planets, carrier support plate, and output flange have output pin insertion holes into which output pins are inserted, and the opening diameter of the output pin insertion holes is set to be equal to or greater than the sum of the amount of eccentricity when the planets rotate eccentrically and the outer diameter of the output pins, thereby improving the efficiency of transmission of rotational power. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of a differential gear reducer according to a first embodiment. [Figure 2] FIG. 1 is an exploded perspective view of a differential gear reducer according to a first embodiment. [Figure 3] 5A and 5B are diagrams for explaining the operation of the differential gear reducer according to the first embodiment. [Figure 4] FIG. 6 is a cross-sectional view of a differential gear reducer according to a second embodiment. [Figure 5] FIG. 10 is a plan view of a first planetary gear and a second planetary gear of a differential gear reducer according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a differential gear reducer according to an embodiment of the present disclosure will be described in detail with reference to the drawings. Note that the same reference numerals in the various drawings indicate the same or corresponding parts.

[0010] Embodiment 1 FIG. 1 is a cross-sectional view of a differential gear reducer according to a first embodiment. FIG. 1 is a cross-sectional view in a direction parallel to the camshaft. As shown in FIG. 1, the differential gear reducer 100 of this embodiment includes a cylindrical camshaft 9, an annular planetary gear 1 attached to the camshaft 9 via rollers 10, an annular internal gear 2 having a gear on its inner periphery that meshes with a gear formed on the outer periphery of the planetary gear 1, and an annular carrier support plate 11 and output flange 12 disposed opposite each other with the planetary gear 1 sandwiched therebetween. The camshaft 9 rotates eccentrically with an eccentricity e. Therefore, the planetary gear 1 also rotates eccentrically with an eccentricity e. The planetary gear 1, the carrier support plate 11, and the output flange 12 are each provided with output pin insertion holes 3, 4, and 5 of the same diameter at the same positions in a direction parallel to the camshaft 9. The differential gear reducer 100 of this embodiment also has output pins 14 inserted into output pin insertion holes 3, 4, and 5 provided in the planetary gear 1, carrier support plate 11, and output flange 12, respectively. These output pins 14 are not fixed to any of the planetary gear 1, carrier support plate 11, and output flange 12. The opening diameters of the output pin insertion holes 3, 4, and 5 provided in the planetary gear 1, carrier support plate 11, and output flange 12, respectively, are set to be equal to or greater than the sum of the eccentricity e of the camshaft 9 and the outer diameter of the output pin 14, so that the output pin 14 can move freely. The internal gear 2 is fixed to a case 17 with bolts 18. The carrier support plate 11 and the output flange 12 are arranged in the case 17 via bearings 16.

[0011] One axial end of the output pin 14 is restricted by the output flange 12, and the other end is restricted by the case 17. In other words, the output pin 14 rolls freely in the output pin insertion holes 3, 4, and 5 provided in the planet 1, carrier support plate 11, and output flange 12, respectively.

[0012] FIG. 2 is an exploded perspective view of the differential gear reducer according to this embodiment. However, the camshaft, case, and other components are omitted from FIG. 2. To facilitate understanding of the relationship between the output pin 14, the carrier pin 13, and the holes in the output flange 12, only the output flange 12 is shown in cross section in FIG. 2. The carrier support plate 11 and the output flange 12 are fastened together by the carrier pin 13. The carrier pin 13 passes through a carrier pin through hole 6 in the planetary gear 1. The opening diameter of the carrier pin through hole 6 in the planetary gear 1 is set to a size such that the planetary gear 1 and the carrier pin 13 do not come into contact with each other even when the planetary gear 1 rotates eccentrically. Specifically, the opening diameter of the carrier pin through hole 6 is set to be larger than the sum of the eccentricity amount e of the camshaft 9 and the outer diameter of the carrier pin 13. As shown in FIG. 1, the carrier support plate 11 and the output flange 12 are rotatably mounted on the camshaft 9 via a bearing 15. The rotational center axes of the carrier support plate 11 and the output flange 12 overlap with the center axis of the annular internal gear 2.

[0013] In the differential gear reducer 100 configured in this manner, when the camshaft 9 rotates eccentrically, the planetary gear 1 rotates eccentrically via the rollers 10. At this time, the planetary gear 1 rotates at a reduced speed in accordance with the ratio between the number of gears on the planetary gear 1 and the number of gears on the internal gear 2. The reduced rotation of the planetary gear 1 is transmitted to the output flange 12 by the output pin 14.

[0014] Fig. 3 is a diagram for explaining the operation of the differential gear reducer according to this embodiment. Fig. 3 is a diagram of the planetary gear 1 and the output flange 12 viewed from the carrier support plate 11 side. In Fig. 3, Fig. 3(a) is the initial position, and Fig. 3(b), Fig. 3(c), and Fig. 3(d) show the cases where the camshaft has rotated 90° clockwise in succession. In Fig. 3, the position indicated by the circle in the center indicates the rotation center position of the planetary gear 1, and the position indicated by the plus sign indicates the rotation center position of the output flange.

[0015] As shown in Figure 3, the output pin 14 is always sandwiched between the output pin insertion hole 3 of the planetary gear 1 and the output pin insertion hole 5 of the output flange 12, so the output pin 14 performs a rolling motion while in contact with the inner circumferential surface of the output pin insertion hole 3 of the planetary gear 1 and the inner circumferential surface of the output pin insertion hole 5 of the output flange 12. This rolling motion of the output pin 14 allows the rotational power of the planetary gear 1, which is rotating at a reduced speed, to be transmitted to the output flange 12. In this way, in the differential gear reducer of this embodiment, the output pin operates by a rolling motion, which reduces mechanical loss. As a result, the differential gear reducer of this embodiment improves the efficiency of transmission of rotational power.

[0016] Furthermore, in the differential gear reducer of this embodiment, the carrier support plate and the output flange, which are arranged opposite each other with the planetary gear therebetween, are fastened together by the carrier pin, so that axial wobble caused by the rolling motion of the output pin is reduced, thereby enabling the differential gear reducer of this embodiment to suppress vibration.

[0017] In the differential gear reducer of this embodiment, the internal gear is fixed to the case, and the carrier support plate and output flange are rotatably supported, but it is also possible to configure the carrier support plate and output flange to be fixed to the case, and the internal gear to be rotatably supported. In this case, the internal gear serves as a mechanism for extracting reduced rotation output in place of the output flange.

[0018] Embodiment 2 Fig. 4 is a cross-sectional view of a differential gear reducer according to embodiment 2. Fig. 4 is a cross-sectional view in a direction parallel to the camshaft. In the differential gear reducer of this embodiment, the structures of the planets and output pins are different from those of the differential gear reducer of embodiment 1.

[0019] As shown in FIG. 4, in the differential gear reducer 100 of this embodiment, a first planetary gear 1a and a second planetary gear 1b, whose rotational phases differ by 180°, are mounted on a camshaft 9 via rollers 10. The camshaft 9 rotates eccentrically with an eccentricity e. Therefore, both the first planetary gear 1a and the second planetary gear 1b rotate eccentrically with an eccentricity e, but because their rotational phases differ by 180°, the first planetary gear 1a and the second planetary gear 1b are always shifted from each other by twice the eccentricity e. The differential gear reducer 100 of this embodiment also includes a first output pin 14a that transmits the rotational power of the first planetary gear 1a to the output flange 12, and a second output pin 14b that transmits the rotational power of the second planetary gear 1b to the output flange 12. FIG. 4 is a cross-sectional view of the position where the second output pin 14b is provided. 4, at the position where the second output pin 14b is provided, the carrier support plate 11, the output flange 12, the first planetary gear 1a, and the second planetary gear 1b are each provided with output pin insertion holes 4, 5, 20a, and 20b in a direction parallel to the camshaft 9. Furthermore, although not shown, at the position where the first output pin 14a is provided, the carrier support plate 11, the output flange 12, the first planetary gear 1a, and the second planetary gear 1b are each provided with output pin insertion holes 4, 5, 19a, and 19b in a direction parallel to the camshaft 9.

[0020] The first output pin 14a is inserted into output pin insertion holes 19a, 19b, 4, and 5 provided in the first planetary gear 1a, the second planetary gear 1b, the carrier support plate 11, and the output flange 12, respectively. The second output pin 14b is inserted into output pin insertion holes 20a, 20b, 4, and 5 provided in the first planetary gear 1a, the second planetary gear 1b, the carrier support plate 11, and the output flange 12, respectively. The first output pin 14a and the second output pin 14b are not fixed to any of the first planetary gear 1a, the second planetary gear 1b, the carrier support plate 11, and the output flange 12. One axial end of the first output pin 14a and the second output pin 14b is restricted by the output flange 12, and the other axial end is restricted by the case 17.

[0021] The carrier support plate 11 and the output flange 12 are fastened together by a carrier pin 13. The carrier pin 13 passes through carrier pin through holes 6a, 6b provided in the first planetary gear 1a and the second planetary gear 1b, respectively. The opening diameters of the carrier pin through holes 6a, 6b provided in the first planetary gear 1a and the second planetary gear 1b, respectively, are set to a size such that the first planetary gear 1a and the second planetary gear 1b do not come into contact with the carrier pin 13 even when the first planetary gear 1a and the second planetary gear 1b rotate eccentrically. Specifically, the opening diameters of the carrier pin through holes 6a, 6b are set to be larger than the sum of twice the eccentricity amount e of the camshaft and the outer diameter of the carrier pin 13.

[0022] 5 is a plan view of the first planetary gear and the second planetary gear of the differential gear reducer according to this embodiment. As shown in FIG. 5, the opening diameter of the output pin insertion hole 19a, into which the first output pin 14a of the first planetary gear 1a is inserted, is set to be equal to or greater than the sum of the eccentricity e of the camshaft and the outer diameter of the first output pin 14a. On the other hand, the opening diameter of the output pin insertion hole 19b of the second planetary gear 1b, into which the first output pin 14a is inserted, is set to be greater than the sum of twice the eccentricity e of the camshaft and the outer diameter of the first output pin 14a so as not to come into contact with the first output pin 14a. Similarly, the opening diameter of the output pin insertion hole 20b of the second planetary gear 1b, into which the second output pin 14b is inserted, is set to be equal to or greater than the sum of the eccentricity e of the camshaft and the outer diameter of the second output pin 14b. On the other hand, the opening diameter of the output pin insertion hole 20a of the first planetary gear 1a, into which the second output pin 14b is inserted, is set to be larger than the sum of twice the eccentricity e of the camshaft and the outer diameter of the second output pin 14b so as not to come into contact with the second output pin 14b. The opening diameters of the carrier pin through holes 6a, 6b provided in the first planetary gear 1a and the second planetary gear 1b, respectively, are set to be larger than the sum of twice the eccentricity e of the camshaft and the outer diameter of the carrier pin so as not to come into contact with the carrier pin.

[0023] In a differential gear reducer configured in this manner, the planets are configured with two planets whose rotational phases differ by 180°, improving the rotational balance of the planets and suppressing vibration, while also increasing the output torque. Furthermore, as with the differential gear reducer of embodiment 1, the output pins operate by rolling motion, reducing mechanical loss. Therefore, the differential gear reducer of this embodiment improves the efficiency of transmission of rotational power.

[0024] Furthermore, in the differential gear reducer of this embodiment, the carrier support plates and the output flange, which are arranged facing each other with the two planetary gears in between, are fastened together by carrier pins, which reduces axial wobble caused by the rolling motion of the output pins, making it possible to suppress vibrations.

[0025] While the present disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not exemplified are conceivable within the scope of the technology disclosed in this specification, including, for example, cases where at least one component is modified, added, or omitted, and cases where at least one component is extracted and combined with components of another embodiment. [Explanation of symbols]

[0026] 1 planet, 1a first planet, 1b second planet, 2 internal teeth, 3, 4, 5 output pin insertion hole, 6, 6a, 6b carrier pin through hole, 9 camshaft, 10 roller, 11 carrier support plate, 12 output flange, 13 carrier pin, 14 output pin, 14a first output pin, 14b second output pin, 15, 16 bearing, 17 case, 18 bolt, 19a, 19b, 20a, 20b output pin insertion hole, 100 differential gear reducer.

Claims

1. An eccentrically rotating planet, an internal gear having a gear meshing with the planet; a carrier support plate and an output flange arranged opposite to each other with the planetary gear therebetween and fastened together by a carrier pin passing through the planetary gear; an output pin that transmits the eccentric rotation of the planetary gear to the output flange, an opening diameter of a carrier pin through hole provided in the planet and through which the carrier pin passes is set to be larger than the sum of an eccentric amount when the planet rotates eccentrically and an outer diameter of the carrier pin, a differential gear reducer characterized in that the planets, the carrier support plate, and the output flange have output pin insertion holes into which the output pins are inserted, and the opening diameter of the output pin insertion holes is set to be equal to or greater than the sum of the amount of eccentricity when the planets rotate eccentrically and the outer diameter of the output pins.

2. a first planetary gear and a second planetary gear that rotate eccentrically with a rotation phase difference of 180° and the same eccentricity; an internal gear having a gear meshing with the first planet and the second planet; a carrier support plate and an output flange disposed opposite to each other with the first planetary gear and the second planetary gear interposed therebetween and fastened together by a carrier pin passing through the first planetary gear and the second planetary gear; a first output pin that transmits eccentric rotation of the first planetary gear to the output flange, and a second output pin that transmits eccentric rotation of the second planetary gear to the output flange, an opening diameter of a carrier pin through hole, through which the carrier pin provided in the first planetary gear and the second planetary gear passes, is set to be larger than the sum of twice the eccentricity amount and an outer diameter of the carrier pin, a differential gear reducer characterized in that an opening diameter of an output pin insertion hole of the first planetary gear into which the first output pin is inserted is set to be equal to or greater than the sum of twice the amount of eccentricity and an outer diameter of the first output pin, an opening diameter of an output pin insertion hole of the first planetary gear into which the second output pin is inserted is larger than the sum of twice the amount of eccentricity and the outer diameter of the second output pin, and an opening diameter of an output pin insertion hole of the second planetary gear into which the second output pin is inserted is set to be equal to or greater than the sum of twice the amount of eccentricity and the outer diameter of the second output pin, and an opening diameter of an output pin insertion hole of the second planetary gear into which the first output pin is inserted is larger than the sum of twice the amount of eccentricity and the outer diameter of the first output pin.

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