Cycloid reduction gear

Abstract

Provided is a cycloid reduction gear that can be reduced in size and suppressed a weight increase.　The cycloid reduction gear comprises: a plurality of curved plates formed with external teeth and having a center of rotation eccentric to an input shaft; a fixed gear that is formed with internal teeth meshing with the external teeth and rotates the curved plates while revolving the curved plates in accordance with rotation of the input shaft; a plurality of output pins arranged so as to penetrate a pair of the curved plates in the axial direction; an output flange into which one ends of the output pins penetrate; and a carrier member into which other ends of the output pins penetrate, the cycloid reduction gear provided with a first slide protection member disposed between the curved plates and the output flange, and a second slide protection member disposed between the curved plates and the carrier member, the first slide protection member and the second slide protection member being composed of a material having higher hardness than those of the output flange and the carrier member, and the thickness of the first slide protection member in the axial direction being formed thinner than the thickness of the second slide protection member in the axial direction.

Description

Cycloid speed reducer

[0001] The present invention relates to a cycloid speed reducer.

[0002] Conventionally, a cycloid speed reducer is known as a speed reducer. The cycloid speed reducer is used in various applications, for example, in industrial robots and automobile parts. The cycloid speed reducer converts the rotation and torque obtained from a drive unit such as a motor or an internal combustion engine into a predetermined torque and rotational speed.

[0003] Such cycloid speed reducers are known in various forms. For example, as described in Patent Document 1, it includes a pair of curve plates, the curve plates are arranged with a 180° phase shift from each other, and the curve plates are sandwiched between an output flange and a carrier member axially connected by an output pin.

[0004] According to such a cycloid speed reducer, since the curve plates are arranged with a 180° phase shift from each other, vibration can be reduced and the number of meshes can be increased. Since the output side has a cage shape by the output flange and the carrier member, the efficiency and robustness of power transmission can be improved.

[0005] Japanese Patent Application Laid-Open No. 2012-141028

[0006] However, when using a cycloid speed reducer in a running robot or the like, in order to improve power performance, a lighter speed reducer is required. Conventional cycloid speed reducers used iron-based materials in which components such as output flanges and carrier members were quenched, but lightweight metals such as aluminum alloys may be used for weight reduction.

[0007] When a lightweight metal such as an aluminum alloy is used, since the curve plate, the output flange, and the carrier member slide against each other, a sliding protection member is interposed between the curve plate, the output flange, and the carrier member to protect them.

[0008] However, as mentioned above, lighter metals are used for the purpose of weight reduction, so there is a desire to minimize the weight increase caused by adding sliding protection members. On the other hand, for the reasons mentioned above, removing the sliding protection members would reduce the strength of the cycloidal reducer.

[0009] Furthermore, as shown in Figures 4 and 5, the cage-shaped cycloidal reducer transmits output to the output flange 114 via the output pin 113 while a pair of curved plates 111a and 111b revolve around the input shaft 116 and rotate on their own while being phase-shifted from each other.

[0010] With this structure, since the output pin 113 penetrates the output flange 114 and the carrier member 115, the moment acting on the curved plate 111b located on the carrier member 115 side is greater than that acting on the curved plate 111a located on the output flange 114 side. As shown in Figure 5, the carrier member 115 side of the output pin 113 bends, and as a result, a pressing force is constantly generated on the carrier member 115.

[0011] Such pressing forces hinder the smooth rotation of the curved plates 111a and 111b, causing wear and damage to the components. Furthermore, the interposition of the aforementioned sliding protective member increases the length of the output pin 113 by the length of the sliding protective member, which reduces the rigidity of the cage shape. To maintain rigidity, the diameter of the output pin 113 must be increased or the fitting length increased, leading to problems such as an increase in the size and weight of the cycloidal reducer.

[0012] The present invention was made to solve the above problems, and aims to provide a cycloidal speed reducer that can minimize weight increase even when a lightweight metal such as an aluminum alloy is used to reduce the weight of the speed reducer, and when a sliding protective member is used to prevent sliding wear between members that slide in contact with each other, and also enables miniaturization of the cycloidal speed reducer and suppression of weight increase without increasing the diameter of the output pin or the fitting length, even when a sliding protective member is interposed.

[0013] The cycloidal speed reducer according to the present invention, which solves the above problems, comprises: a plurality of curved plates having external teeth formed on them and a rotation center eccentric with respect to the input shaft; a fixed gear having internal teeth that mesh with the external teeth and causing the curved plates to rotate on their own axis while revolving in accordance with the rotation of the input shaft; a plurality of output pins disposed to penetrate the pair of curved plates in the axial direction; an output flange into which one end of the output pins is inserted; and a carrier member into which the other end of the output pins is inserted, wherein the cycloidal speed reducer comprises: a first sliding protective member disposed between the curved plates and the output flange; and a second sliding protective member disposed between the curved plates and the carrier member, wherein the first sliding protective member and the second sliding protective member are made of a material with higher hardness than the output flange and the carrier member, and the axial thickness of the first sliding protective member is formed to be thinner than the axial thickness of the second sliding protective member.

[0014] Furthermore, the cycloidal speed reducer according to the present invention, which solves the above problems, comprises: a plurality of curved plates having external teeth formed on them and a rotation center eccentric with respect to the input shaft; a fixed gear having internal teeth that mesh with the external teeth and causing the curved plates to rotate on their own axis while revolving in accordance with the rotation of the input shaft; a plurality of output pins arranged to penetrate the pair of curved plates in the axial direction; an output flange into which one end of the output pins is inserted; and a carrier member into which the other end of the output pins is inserted, wherein the cycloidal speed reducer comprises: a first sliding protective member disposed between the curved plates and the output flanges; and a second sliding protective member disposed between the curved plates and the carrier member, wherein the insertion length of one end of the output pins into the output flanges is longer than the insertion length of the other end of the output pins into the carrier member.

[0015] The cycloidal speed reducer according to the present invention comprises a first sliding protective member positioned between the curved plate and the output flange, and a second sliding protective member positioned between the curved plate and the carrier member. Since the first and second sliding protective members are made of a material with higher hardness than the output flange and the carrier member, even when lightweight metals such as aluminum alloy are used for the output flange and the carrier member, the cycloidal speed reducer can be made smaller and lighter while maintaining the necessary rigidity by interposing sliding protective members made of a higher hardness material. Furthermore, since the axial thickness of the first sliding protective member is formed to be thinner than the axial thickness of the second sliding protective member, the cycloidal speed reducer can be made larger and heavier.

[0016] Cross-sectional view of an actuator equipped with a cycloidal speed reducer according to an embodiment of the present invention. Enlarged view of section A in Figure 1. Exploded perspective view of a cycloidal speed reducer according to an embodiment of the present invention. Diagram illustrating the operation of a conventional cycloidal speed reducer. Cross-sectional view along line B-B in Figure 4.

[0017] Hereinafter, embodiments of the cycloidal speed reducer according to the present invention will be described with reference to the drawings. Note that the following embodiments are not intended to limit the invention as described in each claim, and not all combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0018] Figure 1 is a cross-sectional view of an actuator equipped with a cycloidal speed reducer according to an embodiment of the present invention, Figure 2 is an enlarged view of section A in Figure 1, and Figure 3 is an exploded perspective view of the cycloidal speed reducer according to an embodiment of the present invention.

[0019] As shown in Figure 1, the cycloidal reducer 10 according to this embodiment is suitably used in actuators 1 and the like that reduce and output the driving force of a motor 2. The actuator 1 is suitably used, for example, in the joint drive points of the legs and arms of a humanoid robot.

[0020] The actuator 1 includes a motor 2 that is powered by a power source (not shown), and the rotation axis of the motor 2 is connected to the input shaft 16 of the cycloidal reducer 10.

[0021] As shown in Figures 2 and 3, the cycloidal reducer 10 according to this embodiment includes an input shaft 16 with a pair of eccentric shafts 17a and 17b formed on its outer circumference, which are arranged with a phase difference of 180° from each other; a pair of curved plates 11a and 11b that mesh with the eccentric shafts 17a and 17b and have external teeth formed on their outer surfaces; a plurality of output pins 13 that are inserted into an output pin bearing 33 which is inserted into a plurality of output pin holes 18a and 18b formed along the circumferential direction of the curved plates 11a and 11b; a fixed gear 12 which has internal teeth that mesh with the external teeth of the curved plates 11a and 11b and rotates the curved plates 11a and 11b while revolving in accordance with the rotation of the input shaft 16; an output flange 14 into which one end of the output pins 13 is inserted; and a carrier member 15 into which the other end of the output pins 13 is inserted.

[0022] Furthermore, a first sliding protection member 21 is positioned between the curved plate 11a on the output flange 14 side and the output flange 14, and a second sliding protection member 22 is positioned between the curved plate 11b on the carrier member 15 side and the carrier member 15.

[0023] The internal teeth 12a of the fixed gear 12 are preferably formed in a pin shape with an external roller. The internal teeth 12a are in contact with the external teeth of the curved plates 11a and 11b, and the presence of the external roller allows for smooth guidance of the rotation and revolution of the curved plates 11a and 11b.

[0024] As shown in Figure 3, the pair of curved plates 11a and 11b are arranged to overlap each other in the axial direction and are formed in a disc shape with external teeth on the outer circumference. The external teeth formed on the outer circumference of the curved plates 11a and 11b are preferably formed in the shape of a curve such as a trochoid. The curved plates 11a and 11b also have the output pin holes 18a and 18b arranged in the circumferential direction as described above, and an input shaft hole 19 through which the input shaft 16 is inserted.

[0025] Output pin bearings 33 are rotatably positioned along the inner circumference of output pin holes 18a and 18b. Output pins 13 are inserted through the output pin bearings 33.

[0026] The output flange 14 is a component that reduces the rotation of the input shaft 16 by the revolution and rotation of the curved plates 11a and 11b and outputs the result. The carrier member 15 holds the curved plates 11a and 11b axially between itself and the output flange 14, forming a cage shape and ensuring the rigidity of the cycloidal reducer 10 according to this embodiment. The output flange 14 and the carrier member 15 are made of lightweight metals such as aluminum alloy for the purpose of reducing weight.

[0027] In conventional cycloidal speed reducers, power to the curved plate is transmitted through output pins, but the force applied to the output pins is heavily biased due to the phase relationship of the gears. However, by configuring the cycloidal speed reducer 10 according to this embodiment in a cage shape, the force bending the output pins 13 in the rotational direction is distributed, preventing excessive bending of specific output pins and thus suppressing the aforementioned bias. Furthermore, the output flange 14 and carrier member 15 may be made of low-density iron-based materials such as magnesium alloy or titanium, in addition to the aluminum alloy described above, or materials that have lower surface hardness than iron-based materials but a superior strength / weight ratio. It is also possible to use synthetic resin materials since the sliding parts are covered.

[0028] The first sliding protective member 21 is an annular member formed in a disc shape corresponding to the end face shape of the output flange 14, with multiple through holes 23 formed along the circumferential direction through which the output pin 13 is inserted, and a central hole 24 formed in the center through which the input shaft 16 can be inserted.

[0029] The second sliding protective member 22 is a ring member attached according to the output pin 13, and is press-fitted into the carrier member 15 at the position where the output pin 13 is inserted.

[0030] As shown in Figure 2, the axial thickness of the first sliding protective member 21 is formed to be thinner than the axial thickness of the second sliding protective member 22, and the penetration length L1 of the output pin 13 into the output flange 14 is longer than the penetration length L2 of the output pin 13 into the carrier member 15.

[0031] The first sliding protection member 21 and the second sliding protection member 22 are made of a material with higher hardness than the output flange 14 and the carrier member 15. For example, hardened iron-based materials (such as SK material or SUJ material) are preferably used. In addition to hardened iron-based materials, any material that is relatively stronger against sliding than the constituent materials such as the carrier member 15 can be used. The carrier member 15 may also be made of synthetic resin and an oil-less sliding material may be embedded in it.

[0032] As described above, in the cycloidal reducer 10 according to this embodiment, since the first sliding protection member 21 and the second sliding protection member 22 are arranged between the output flange 14 and the carrier member 15 and the curved plates 11a and 11b, the output flange 14 and the carrier member 15 can be made of a lightweight metal such as an aluminum alloy, and the cycloidal reducer 10 according to this embodiment can be made smaller and lighter.

[0033] Furthermore, since the first sliding protection member 21 is formed thinner than the second sliding protection member 22, the cycloidal reducer 10 according to this embodiment can be made smaller and lighter by increasing the thickness of the second sliding protection member 22 on the carrier member 15 side, which is subjected to a larger bending moment, in order to ensure rigidity, while reducing the weight of the first sliding protection member 21.

[0034] Furthermore, by making the first sliding protective member 21 thin, the distance between the output flange 14 and the carrier member 15 can be shortened, thereby reducing the bending moment received by the output pin 13, and increasing the rigidity of the cycloidal reducer 10 according to this embodiment.

[0035] Furthermore, since the penetration length of the output pin 13 is formed such that the penetration length L1 into the output flange 14 is longer than the penetration length L2 into the carrier member 15, it is possible to reduce the weight of the cycloidal reducer 10 according to this embodiment without reducing rigidity and strength.

[0036] The cycloidal reducer 10 according to this embodiment has been described in the case where a motor is attached to the input shaft 16, but the power source attached to the input shaft 16 is not limited to a motor, and various conventionally known power sources can be used. Furthermore, the cycloidal reducer 10 according to this embodiment has been described in the case where a pair of curved plates 11a and 11b are provided, but the number of curved plates is not limited to one pair, for example, three curved plates may be used and arranged with a phase difference of 120° between each curved plate. It is clear from the description of the claims that such modified or improved forms may also be included in the technical scope of the present invention.

[0037] 1 Actuator, 10 Cycloidal reducer, 11a, 11b Curved plates, 12 Fixed gear, 13 Output pin, 14 Output flange, 15 Carrier member, 16 Input shaft, 21 First sliding protective member, 22 Second sliding protective member, L1, L2 Penetration length.

Claims

1. A cycloidal speed reducer comprising: a plurality of curved plates having external teeth formed on them and a rotation center eccentric with respect to an input shaft; a fixed gear having internal teeth that mesh with the external teeth and causing the curved plates to rotate on their own axis while revolving in accordance with the rotation of the input shaft; a plurality of output pins disposed to penetrate the pair of curved plates in the axial direction; an output flange into which one end of the output pins is inserted; and a carrier member into which the other end of the output pins is inserted, wherein the cycloidal speed reducer comprises: a first sliding protective member disposed between the curved plates and the output flange; and a second sliding protective member disposed between the curved plates and the carrier member, wherein the first sliding protective member and the second sliding protective member are made of a material with higher hardness than the output flange and the carrier member, and the axial thickness of the first sliding protective member is formed to be thinner than the axial thickness of the second sliding protective member.

2. The cycloidal speed reducer according to claim 1, wherein the first sliding protective member is formed as an annular member corresponding to the axial end face of the curved plate, and a plurality of through holes through which the output pin can be inserted are formed.

3. A cycloidal speed reducer according to claim 1, characterized in that the second sliding protective member consists of a plurality of ring members inserted around the outer circumference of each of the output pins.

4. A cycloidal speed reducer according to claim 1, characterized in that the output pins are arranged at predetermined intervals along the circumferential direction of the curved plate.

5. A cycloidal speed reducer according to claim 1, characterized in that the output pin is assembled to the curved plate via a bearing member.

6. A cycloidal speed reducer comprising: a plurality of curved plates having external teeth formed on them and a rotation center eccentric with respect to an input shaft; a fixed gear having internal teeth that mesh with the external teeth and causing the curved plates to rotate while revolving in accordance with the rotation of the input shaft; a plurality of output pins disposed to penetrate the pair of curved plates in the axial direction; an output flange into which one end of the output pins is inserted; and a carrier member into which the other end of the output pins is inserted, wherein the cycloidal speed reducer comprises: a first sliding protective member disposed between the curved plates and the output flanges; and a second sliding protective member disposed between the curved plates and the carrier member, characterized in that the insertion length of one end of the output pins into the output flanges is longer than the insertion length of the other end of the output pins into the carrier member.

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