Planetary reduction gear and method for manufacturing the same

Abstract

To provide a planetary reduction gear including an internal gear that is simply joined to a cylindrical part of a case, and to provide a method for manufacturing the same.SOLUTION: A planetary reduction gear 1 includes: an internal gear 5 fixed to a case 10; a sun gear 2 forming an input shaft 6; and a planet gear 3 and a planetary carrier 4 connected to an output shaft 7, a coupling groove 19 for plastic flow coupling is formed in the internal gear 5, the internal gear 5 is inserted into a cylindrical part 12 of the case 10, and the cylindrical part 12 is partially pressed for plastic-flow coupling the internal gear 5 to the cylindrical part 12.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a planetary gear reducer and a method for manufacturing the same.

Background Art

[0002] Conventionally, there has been a planetary gear reducer in which an internal gear is fixed to a case, a sun gear is connected to an input shaft, and a planetary gear and a planetary carrier are connected to an output shaft (see, for example, Patent Document 1). In a conventional planetary gear reducer, when fixing the internal gear to the case, protrusions are provided on both the outer periphery of the internal gear and the cylindrical portion of the case for circumferential fixing, and for axial fixing, a snap ring or the like is used for fixing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the conventional fixing method has a problem that the structure becomes complicated. Therefore, an object of the present invention is to provide a planetary gear reducer and a method for manufacturing the same that can easily fix an internal gear to a case.

Means for Solving the Problems

[0005] A first means is a planetary gear reducer in which an internal gear is fixed to a case, a sun gear forms an input shaft, and a planetary gear and a planetary carrier are connected to an output shaft, wherein a coupling groove for plastic flow coupling is formed in the internal gear, the internal gear is inserted into a cylindrical portion of the case, a part of the cylindrical portion is pressurized, the part of the cylindrical portion is caused to flow into the coupling groove, and the internal gear is plastically flow-coupled to the cylindrical portion.

[0006] In means 2, in means 1, a part of the cylindrical portion is a stepped portion formed on the inner circumference of the cylindrical portion, a coupling groove for plastic flow coupling is formed on the outer circumference of the internal gear, the internal gear is inserted into the cylindrical portion, and instead of a punch, the stepped portion is pressed by the internal gear, the stepped portion is caused to flow into the coupling groove, and the internal gear is plastically flow-coupled to the cylindrical portion.

[0007] In means 3, in means 1, a part of the cylindrical portion is a convex portion formed on the inner circumference of the cylindrical portion, a coupling groove for plastic flow coupling is formed on the inner circumference of the internal gear, the internal gear is inserted into the cylindrical portion, a punch is inserted inside the internal gear, the convex portion is pressed by the punch, the convex portion is caused to flow into the coupling groove, and the internal gear is plastically flow-coupled to the cylindrical portion.

[0008] In means 4, in the means according to any one of means 1 to 3, the coupling groove is formed of a plurality of circumferential grooves and a knurl groove.

[0009] In means 5, in the means according to any one of means 1 to 3, a part of the cylindrical portion is made of an aluminum alloy.

[0010] Means 6 is a method for manufacturing a planetary gear reducer in which an internal gear is fixed to a case, a sun gear forms an input shaft, and a planetary gear and a planetary carrier are connected to an output shaft. A coupling groove for plastic flow coupling is formed on the outer circumference of the internal gear, the internal gear is inserted into the cylindrical portion of the case, and instead of a punch, the stepped portion formed on the inner circumference of the cylindrical portion is pressed by the internal gear, the stepped portion is caused to flow into the coupling groove, and the internal gear is plastically flow-coupled to the cylindrical portion.

[0011] Means 7 is a method for manufacturing a planetary gear reducer in which an internal gear is fixed to a case, a sun gear forms an input shaft, and a planetary gear and a planetary carrier are connected to an output shaft. A coupling groove for plastic flow coupling is formed on the inner circumference of the internal gear, the internal gear is inserted into the cylindrical portion of the case, a punch is inserted inside the internal gear, the convex portion formed on the inner circumference of the cylindrical portion is pressed by the punch, the convex portion is caused to flow into the coupling groove, and the internal gear is plastically flow-coupled to the cylindrical portion.

Advantages of the Invention

[0012] According to the present invention, the internal gear can be easily coupled to the case.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0015] In recent years, with the electrification of vehicles, a drive device combining a motor, an inverter, and a gear has been proposed instead of the combination of an engine and a transmission. Since this drive device has a simple configuration, it is being made compact. In the drive device of the present embodiment, a planetary gear reducer is used in the mechanism for taking out the output of the motor.

[0016] As shown in FIG. 1, the planetary gear reducer 1 is composed of a sun gear 2, planetary gears 3, a planetary carrier 4 that picks up the revolution motion of the planetary gears 3, and an internal gear 5.

[0017] The planetary gear reducer 1 is of the planetary type. The internal gear 5 of the reducer 1 is fixed to the cylindrical portion 12 of the case 10, and the sun gear 2 serves as the input shaft 6.

[0018] The planetary gear 3 and the planetary carrier 4 are connected to the output shaft 7. The output shaft 7 rotates in the same direction as the input shaft 6 of the sun gear 2 and is decelerated. Although not shown in the figure, gears are formed on the inner circumference of the internal gear 5, and the planetary gear 3 meshes with these gears. The input shaft 6 of the sun gear 2 is connected to the output shaft of a motor (not shown).

[0019] The planetary gear reducer 1 is provided with a sleeve 8 on the output shaft 7. The sleeve 8 is spline-fitted on the output shaft 7 and on the inner peripheral portion of the planetary carrier 4. The sleeve 8 slides on the output shaft 7 by the operation of the shift arm 9.

[0020] When the sleeve 8 is in the position shown in Fig. 1, the power from the input shaft 6 is transmitted in sequence to the sun gear 2, the shaft 13 of the planetary gear 3, the planetary carrier 4, and the output shaft 7 as indicated by the arrow X, and is decelerated, for example, at a ratio of 1 to 6. When the sleeve 8 slides leftward from the position shown in the figure due to the operation of the shift arm 9, the power from the input shaft 6 is transmitted in sequence to the sun gear 2 and the output shaft 7 as indicated by the arrow Y, and is directly connected at a ratio of 1 to 1.

[0021] [Embodiment 1] The configuration of the planetary gear reducer 1 will be described. Figs. 2 and 3 are diagrams schematically showing the connection between the case and the internal gear. The case 10 is provided with a cylindrical portion 12, and a stepped portion (a part of the cylindrical portion 12) 15 having a diameter smaller than the inner diameter of the cylindrical portion 12 is formed on the cylindrical portion 12. A notch portion 17 is formed on the outer peripheral portion of the end portion 5A of the internal gear 5 over the circumferential direction. A coupling groove 19 for plastic flow coupling is formed on the outer peripheral surface of the notch portion 17. As shown in Fig. 4, this coupling groove 19 includes a plurality of circumferential grooves 19A extending in the circumferential direction and a knurled groove 19B with fine irregularities where two lines cross each other in a cross shape. Although not shown in the figure, the knurled groove 19B may be a linear flat pattern formed by intersecting with the circumferential groove 19A. The knurled groove 19B is formed by knurling by cutting or rolling.

[0022] The internal gear 5 is plastically flow-coupled to the cylindrical portion 12 of the case 10. The cylindrical portion 12 is made of an aluminum alloy, and the internal gear 5 is made of a metal having a higher hardness than the aluminum alloy of the cylindrical portion 12. The cylindrical portion 12 and the internal gear 5 have a hardness difference.

[0023] As shown by the arrow A in FIG. 3, the internal gear 5 is inserted into the cylindrical portion 12 of the case 10. As shown in FIG. 2, with the internal gear 5 held on the inner peripheral portion of the cylindrical portion 12, a pressing force is applied to the metal internal gear 5 in the direction indicated by the arrow A using a press machine. Although not shown in the drawings, the press machine includes a die mechanism that supports the cylindrical portion 12 of the case 10 so as to resist the pressing force. Further, although not shown in the drawings, the press machine can include a restraint ring that is disposed on the outer periphery of the cylindrical portion 12 and restrains the outward expansion of the stepped portion 15 in the circumferential direction.

[0024] Due to this pressing force, the engaging portion 17A of the notch portion 17 of the internal gear 5 presses the stepped portion (inner peripheral side) 15 of the cylindrical portion 12, and due to the pressing force, the stepped portion 15 of the cylindrical portion 12 undergoes plastic deformation. As a result, the stepped portion 15 flows into the plurality of coupling grooves 19 of the internal gear 5. That is, in the first embodiment, by pressing the stepped portion (inner peripheral side) 15 with the internal gear 5 instead of a punch, the internal gear 5 can be plastically flow-bonded to the stepped portion 15.

[0025] The results of the verification test will be described. A 1 / 4 scale model with an internal gear outer diameter of 40 mm was used, the depth of the circumferential groove 19A was set to 1 mm, the depth of the knurl groove 19B was set to 0.4 mm, and plastic flow bonding was performed. When the pressing force was 99.0 kN and the pushing-in amount of the internal gear 5 was 1.15 mm, the torque strength was 432.1 Nm. When the pressing force was 125.1 kN and the pushing-in amount of the internal gear 5 was 1.48 mm, the torque strength was 773.2 Nm. Also, when the pressing force was 123.2 kN and the pushing-in amount of the internal gear 5 was 1.46 mm, the shaft-pulling strength was 20.2 kN. The results of all the verification tests have confirmed that they are at a level that can sufficiently withstand the strength and durability as the planetary gear reducer 1.

[0026] The plastically deformed stepped portion 15 flows into the circumferential groove 19A and the serration groove 19B of the coupling groove 19, filling the circumferential groove 19A and the serration groove 19B. As a result, the internal gear 5 mechanically engages with the stepped portion 15. The circumferential groove 19A and the serration groove 19B of the internal gear 5 and the joint surface of the stepped portion 15 are in a state where a high friction state is maintained due to the action of residual stress caused by the pressing of the internal gear 5. At this time, the circumferential groove 19A maintains a high friction state in the axial direction of the internal gear 5, and the serration groove 19B maintains a high friction state in the rotational direction. Therefore, between the stepped portion 15 and the internal gear 5, a high shear strength is ensured in the axial direction by the circumferential groove 19A and in the rotational direction by the serration groove 19B, together with the additional component due to the compressive stress during plastic flow bonding, and sufficient strength is ensured. Thus, a high-strength bond utilizing the plastic flow of the stepped portion 15 can be achieved.

[0027] According to the first embodiment, a notch portion 17 having the coupling groove 19 of the internal gear 5 is fitted into the inner peripheral portion of the stepped portion 15, the stepped portion 15 is pressed by the internal gear 5, the stepped portion 15 is plastically deformed, the stepped portion 15 is caused to flow into the coupling groove 19 of the notch portion 17, and the internal gear 5 and the stepped portion 15 are coupled by mechanical engagement. For this reason, the internal gear 5 can be easily coupled to the stepped portion 15, the weight and cost of the parts can be reduced, and the labor in the production process can be reduced.

[0028] A coupling groove 19 for plastic flow bonding is formed on the outer periphery of the internal gear 5, the internal gear 5 is inserted into the cylindrical portion 12 of the case 10, and instead of a punch, the internal gear 5 presses the stepped portion 15 of the cylindrical portion 12 to plastically flow bond the internal gear 5 to the cylindrical portion 12. According to the manufacturing method of the planetary gear reducer 1, the internal gear 5 and the cylindrical portion 12 can be easily coupled by simply pressing the stepped portion 15 of the cylindrical portion 12 with the internal gear 5.

[0029] [Embodiment 2] FIG. 5 is a diagram schematically showing the coupling between the case and the internal gear. In FIG. 5, the same parts as those in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted.

[0030] The case 10 is provided with a cylindrical portion 12, and a convex portion (a part of the cylindrical portion 12) 20 for sandwiching the end portion 5A of the internal gear 5 is formed on the cylindrical portion 12. An annular accommodation groove 25 for accommodating the end portion 5A of the internal gear 5 is formed between the cylindrical portion 12 and the convex portion 20. A coupling groove 21 for plastic flow bonding is formed on the inner periphery of the end portion 5A of the internal gear 5. As shown in FIG. 4, this coupling groove 21 includes a circumferential groove 21A and a knurled groove 21B. Although not shown in the figure, a gear with which the planetary gear 3 meshes is formed on the inner periphery of the internal gear 5, and the coupling groove 21 for plastic flow bonding is formed closer to the open end of the end portion 5A, distinguished from the gear.

[0031] As shown by the arrow A in FIG. 5, the internal gear 5 is inserted into the cylindrical portion 12 of the case 10. The end portion 5A of the internal gear 5 is fitted between the cylindrical portion 12 and the convex portion 20. In this state, a metal punch 27 is inserted into the inner peripheral portion of the internal gear 5.

[0032] A punch notch portion 28 is formed to extend in the circumferential direction on the outer peripheral portion of the end portion 27A of the punch 27. The punch notch portion 28 is fitted to the inner peripheral portion of the convex portion 20 of the cylindrical portion 12, and the punch abutting portion 29 of the punch notch portion 28 abuts against the convex portion 20 of the cylindrical portion 12.

[0033] Using a press machine (not shown), a pressing force is applied to the metal punch 27 in the direction shown by the arrow A.

[0034] Due to this pressing force, the punch abutting portion 29 of the punch notch portion 28 of the punch 27 presses the convex portion 20 of the cylindrical portion 12, and the convex portion 20 is plastically deformed by the pressing force. As a result, the convex portion 20 flows into the coupling groove 21 on the inner peripheral portion of the internal gear 5. That is, in the second embodiment, by pressing the convex portion 20 with the punch 27, the internal gear 5 can be plastically flow bonded to the convex portion 20.

[0035] The plastically deformed convex portion 20 flows into the peripheral groove 21A and the knurl groove 21B of the coupling groove 21, filling the coupling groove 21. As a result, the internal gear 5 mechanically engages with the outer peripheral portion of the convex portion 20. The coupling groove 21 in the inner peripheral portion of the internal gear 5 and the joint surface of the convex portion 20 are in a state where a high friction state is maintained by the action of residual stress due to the pressing of the internal gear 5. At this time, the peripheral groove 21A maintains a high friction state in the axial direction of the internal gear 5, and the knurl groove 21B maintains a high friction state in the rotational direction. Therefore, between the convex portion 20 and the internal gear 5, a high shear strength is ensured in the axial direction by the peripheral groove 21A and in the rotational direction by the knurl groove 21B, together with the additional component due to the compressive stress during plastic flow coupling, and sufficient strength is ensured. Thus, a high-strength coupling utilizing the plastic flow of the convex portion 20 can be achieved.

[0036] According to the second embodiment, since the convex portion 20 is plastically deformed, the convex portion 20 is made to flow into the coupling groove 21, and the internal gear 5 and the convex portion 20 are coupled by mechanical engagement, the internal gear 5 can be easily coupled to the convex portion 20, the weight and cost of the parts can be reduced, and the labor in the production process can be reduced. Note that when the punch 27 is pressurized, a restraint ring may be disposed outside the cylindrical portion 12 in order to restrain the expansion of the cylindrical portion 12 in the outer peripheral direction.

[0037] A coupling groove 21 for plastic flow coupling is formed on the inner periphery of the internal gear 5, the internal gear 5 is fitted between the cylindrical portion 12 and the convex portion 20, a punch 27 is inserted inside the internal gear 5, and the convex portion (inner peripheral side) 20 is pressed by the punch 27, thereby plastically flow coupling the internal gear 5 to the convex portion 20. According to the manufacturing method of the planetary gear reducer 1, the internal gear 5 and the cylindrical portion 12 can be easily coupled only by pressing the convex portion 20 of the cylindrical portion 12 with the punch 27.

[0038] [Experimental Results] An experiment on plastic flow coupling was conducted using a 1 / 4 reduced model with a diameter of 40 mm. In the pressing method using the internal gear 5 of the above-described Embodiment 1, when the pressing force was 124 kN and the pushing-in amount of the internal gear 5 was 1.5 mm, the torque strength was 773 Nm and the shaft-pulling strength was 20 kN. Also, in the pressing method using the punch 27 of the above-described Embodiment 2, when the pressing force was 114 kN and the pushing-in amount of the internal gear 5 was 1.5 mm, the torque strength was 400 Nm or more and the shaft-pulling strength was 23 kN.

[0039] No significant difference in strength was observed depending on the above pressing method. When the target product diameter is 160 mm in diameter and the torque target is 2000 kN, the experimental results at a diameter of 40 mm show that the cross-sectional area is 4 times and the moment diameter is 4 times. Therefore, when the target product diameter is 160 mm in diameter, 16 times the strength can be expected compared to when the diameter is 40 mm. A torque strength of 400 Nm or more is strength data that can sufficiently achieve the target. In Embodiment 1, the coupling groove 19 is formed in the outer peripheral portion of the internal gear 5, and in Embodiment 2, the coupling groove 21 is formed in the inner peripheral portion of the internal gear 5. Therefore, in comparison with Embodiment 2, the processing cost is reduced in Embodiment 1.

[0040] As described above, the present invention has been described based on one embodiment, but the present invention is not limited thereto. The magnitude of the load applied to the internal gear 5 or the punch 27, the stroke and pressing time of the internal gear 5 or the punch 27, the number and groove depth of the coupling grooves 19 and 21, and other detailed configurations can be arbitrarily changed according to the size of the planetary gear reducer 1.

[0041] Also, in the above embodiment, the planetary gear reducer of an electrified vehicle has been described, but needless to say, the present invention is not limited thereto, and it can be applied to any planetary gear reducer such as a planetary gear reducer of an internal combustion engine vehicle.

Explanation of Reference Numerals

[0042] 1 Planetary gear reducer 2 Sun gear 3 Planetary gear 4 Planetary carrier 5 Internal gear 6 Input shaft 7 Output shaft 10 Case 12 Cylindrical part 13 Axis of the planetary gear 15 Step part (a part of the cylindrical part) 17 Notch part 19, 21 Coupling groove 20 Protrusion part (a part of the cylindrical part) 25 Receiving groove 27 Punch 28 Punch notch part 29 Punch contact part

Claims

1. A planetary gear reducer in which an internal gear is fixed to a case, a sun gear forms an input shaft, and a planetary gear and a planetary carrier are connected to an output shaft, a coupling groove for plastic flow coupling is formed in the internal gear, the internal gear is inserted into a cylindrical portion of the case, a part of the cylindrical portion is pressed, the part of the cylindrical portion is caused to flow into the coupling groove, and the internal gear is plastically flow-coupled to the cylindrical portion, a planetary gear reducer.

2. A part of the cylindrical portion is a stepped portion formed on the inner circumference of the cylindrical portion, a coupling groove for plastic flow coupling is formed on the outer circumference of the internal gear, the internal gear is inserted into the cylindrical portion, the stepped portion is pressed with the internal gear instead of a punch, the stepped portion is caused to flow into the coupling groove, and the internal gear is plastically flow-coupled to the cylindrical portion, The planetary gear reducer according to claim 1.

3. A part of the cylindrical portion is a convex portion formed on the inner circumference of the cylindrical portion, a coupling groove for plastic flow coupling is formed on the inner circumference of the internal gear, the internal gear is inserted into the cylindrical portion, a punch is inserted inside the internal gear, the convex portion is pressed by the punch, the convex portion is caused to flow into the coupling groove, and the internal gear is plastically flow-coupled to the cylindrical portion, The planetary gear reducer according to claim 1.

4. The coupling groove is formed of a plurality of circumferential grooves and a knurl groove, The planetary gear reducer according to any one of claims 1 to 3.

5. A part of the cylindrical portion is made of an aluminum alloy, The planetary gear reducer according to any one of claims 1 to 3.

6. A method for manufacturing a planetary gear reducer in which an internal gear is fixed to a case, a sun gear forms an input shaft, and a planetary gear and a planetary carrier are connected to an output shaft, a coupling groove for plastic flow coupling is formed on the outer circumference of the internal gear, the internal gear is inserted into a cylindrical portion of the case, the stepped portion formed on the inner circumference of the cylindrical portion is pressed with the internal gear instead of a punch, the stepped portion is caused to flow into the coupling groove, and the internal gear is plastically flow-coupled to the cylindrical portion, a method for manufacturing a planetary gear reducer.

7. A method for manufacturing a planetary gear reducer in which an internal gear is fixed to a case, a sun gear forms an input shaft, and a planetary gear and a planetary carrier are connected to an output shaft, a coupling groove for plastic flow coupling is formed on the inner circumference of the internal gear, the internal gear is inserted into a cylindrical portion of the case, a punch is inserted inside the internal gear, the convex portion formed on the inner circumference of the cylindrical portion is pressed by the punch, the convex portion is caused to flow into the coupling groove, and the internal gear is plastically flow-coupled to the cylindrical portion, Method for manufacturing a planetary gear reducer.

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