Power split decoupler

Abstract

The application discloses a power split type speed reducer and relates to the technical field of speed reduction transmission. The speed reducer comprises a shell and an input gear, a first planetary gear, a first ring gear, a planet carrier, a second-stage small sun gear, an idler gear and a second ring gear arranged in the shell. The input gear, the first planetary gear, the first ring gear and the planet carrier form a epicyclic gear train, the second-stage small sun gear, the idler gear and the second ring gear form a fixed-axle gear train, and the two gear trains are coupled through a double gear to form a composite transmission mechanism. Input power is split into two paths through the planetary gear train, one path is directly transmitted to an output end through the planet carrier, and the other path is transmitted to the output end through the first ring gear, the second-stage small sun gear, the idler gear and the second ring gear, and the two paths of power are combined and output at the output component. The application significantly reduces the load of a single transmission component through power splitting, realizes large-torque transmission while maintaining small size and light weight, has high power density, and has a compact structure, and is particularly suitable for high-load transmission occasions with limited space, such as robot joints.

Description

Technical Field

[0001] This invention relates to the field of speed reducer technology, and in particular to a power split speed reducer. Background Technology

[0002] With the rapid development of robotics technology, high power density is required for transmission devices in humanoid robot joints and other applications. For example, the knee and hip joints of a humanoid robot need to output enormous torque to support and drive the entire body within the limited diameter space of the thigh and calf. Only reducers with sufficiently small size and high torque density can be embedded in biomimetic joint structures; otherwise, the robot will be bulky and cumbersome, losing the dexterity and practicality of a human form. Therefore, developing small-sized reducers with high load-bearing capacity, while ensuring high load capacity and reducing inertia, enabling robots to achieve agile running, jumping, and other dynamic movements, is one of the keys to realizing anthropomorphic movement.

[0003] Existing power-splitting planetary reducers generally include a reducer housing, input shaft, output shaft, input gear, planetary gears, planetary carrier end plates, internal gear ring, idler gear, and idler gear shaft. The input power is transmitted in two paths: one path passes through the input gear, planetary gears, and planetary gear shaft to the output shaft; the other path passes through the input gear, planetary gears, internal gear ring, and idler gear to the output gear on the output shaft. The two power paths are then combined and output from the output shaft. This structure reduces the load on individual components through power splitting.

[0004] However, the aforementioned planetary reducer has the following shortcomings: First, the second power path meshes with the output gear on the output shaft via the idler gear. The output gear is located on the output shaft body, and the diameter and arrangement of the final stage meshing pair are limited by the structure of the output shaft. Second, multiple planetary gear shafts and planetary carrier connecting shafts need to be installed between the planetary carrier end plate and the output shaft to achieve a fixed connection. This results in a large number of axially connected components and parts, making the structure less compact. Third, the inner end of the input shaft is housed in the inner end groove of the output shaft. The input shaft and output shaft are a solid nested structure, and a through hollow channel cannot be formed in the center of the reducer. This is not conducive to the installation of cables and pipes inside the robot joints, nor is it conducive to weight reduction.

[0005] In view of this, how to make the reducer structure more compact and adapt to the hollow wiring requirements of robot joints while ensuring the power shunting capacity is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a power split reducer that, while ensuring high torque carrying capacity, reduces the number of parts and volume, and achieves a through-hole structure, to meet the application requirements of high power density transmission applications, especially robot joints.

[0007] The present invention provides a power split type reducer, comprising a reducer housing, an input gear, at least one first planetary gear meshing with the input gear, a first gear ring meshing with each of the first planetary gears and rotatably supported on the reducer housing about its own axis, and a planet carrier coaxially arranged with the input gear and supporting the rotation of each of the first planetary gears; further comprising:

[0008] The second-stage small sun gear is coaxially and fixedly connected to the first gear ring, forming a double gear with the first gear ring;

[0009] At least one idler gear, each of the idler gears meshing with the second-stage small sun gear, and the rotation axis of each of the idler gears being fixed to the reducer housing;

[0010] The second gear ring is an internal gear ring that meshes with each of the idler gears; the second gear ring is fixedly connected to the planetary carrier to form an output component, which is rotatably supported on the reducer housing;

[0011] The input power is split into a first power path and a second power path via the input gear and each of the first planetary gears. The first power path is transmitted to the output component via the planetary carrier, and the second power path is transmitted to the output component via the first gear ring, the second stage small sun gear, each of the idler gears, and the second gear ring. The two power paths are combined in the output component and then output by the output component.

[0012] Furthermore, it also includes an input shaft, which is coaxially and fixedly connected to the input gear via a key connection; the input shaft is a hollow shaft with a first hollow channel running through it along the axial direction; a second hollow channel running through it along the axial direction is provided at the central axis of the planetary carrier, and the second hollow channel is coaxially arranged with the first hollow channel.

[0013] Furthermore, the input gear is disposed inside the planetary carrier.

[0014] Furthermore, there are multiple first planetary gears and multiple idler gears. The multiple first planetary gears constitute a first planetary gear set, and the multiple idler gears constitute an idler gear set. The first planetary gear set and the idler gear set are respectively disposed on opposite sides of the planet carrier along the axial direction.

[0015] Furthermore, the number of the first planetary gears is three or four, the number of the idler gears is three or four, and both the first planetary gears and the idler gears are evenly distributed along the circumferential direction.

[0016] Furthermore, the first gear ring and the second-stage small sun gear are integrally formed or fixed by key connection.

[0017] Furthermore, the second gear ring and the planetary carrier are integrally formed.

[0018] Furthermore, the first planetary gear and the idler gear can be gears of the same specification, the first gear ring and the second gear ring can be gear rings of the same specification, and the input gear and the second stage small sun gear can be gears of the same specification.

[0019] Furthermore, the tooth profiles of the input gear, the first planetary gear, the first ring gear, the second-stage sun gear, the idler gear, and the second ring gear are all involute tooth profiles.

[0020] Furthermore, the reducer housing includes a housing and a support frame; the gear shafts of each idler wheel are fixed to the support frame, and each idler wheel is rotatably mounted on the corresponding gear shaft via bearings and bushings; the output component is rotatably connected to the support frame via bearings; and the double gear is supported on the housing via bearings.

[0021] Compared with the prior art, the power split reducer of the present invention has the following beneficial effects:

[0022] (1) By fixing the second gear ring to the planetary carrier to form the same output component, the two power paths are combined and output on the output component. Compared with the existing power split type reducer, there is no need to set the output gear on the output shaft, nor is there a need to set multiple planetary gear shafts and connecting shafts connecting the planetary carrier end plate and the output shaft. This reduces the number of parts and axial series links, resulting in a compact structure.

[0023] (2) The second power is transmitted through the second stage small sun gear, idler gear and the second gear ring meshing. The second gear ring has a large diameter, and multiple idler gears can be evenly distributed along its inner circumference to mesh at the same time. The load is shared among multiple meshing pairs, which reduces the single tooth contact stress and bending stress, which is conducive to improving the load-bearing capacity and service life.

[0024] (3) The gear shaft of the idler wheel is fixed to the support frame, and the idler wheel only rotates around its own axis. The support rigidity is good, which is conducive to improving the smoothness of transmission.

[0025] (4) The input shaft is a hollow shaft, and a through hollow channel is provided at the central axis of the planetary carrier. The two are coaxially connected, and cables or pipes can pass through the center of the reducer to meet the internal wiring requirements of the robot joint, which is conducive to reducing weight and increasing power density.

[0026] (5) The first planetary gear set and the idler gear set are respectively set on opposite sides of the planet carrier along the axial direction. The transmission components are integrated in the axial height, which further reduces the axial dimension of the reducer;

[0027] (6) The first planetary gear and idler gear, the first gear ring and the second gear ring, the input gear and the second stage small sun gear can each use gears of the same specification, which reduces the types of parts and reduces manufacturing costs. Moreover, the specification relationship meets the matching conditions of the two speeds, ensuring that the two power sources are normally combined. Attached Figure Description

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0029] Figure 1 This is a cross-sectional structural diagram of the present invention;

[0030] Figure 2 This is a schematic diagram of the end face structure of the present invention.

[0031] Explanation of reference numerals in the attached diagram: 1. Input gear; 2. First planetary gear; 3. First ring gear; 4. Planet carrier; 5. Second stage sun gear; 6. Idler gear; 7. Second ring gear; 8. Reducer housing. Detailed Implementation

[0032] It should be noted that in the description of this specification, the terms "upper", "lower", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0033] Figure 1 This is a cross-sectional structural diagram of the present invention. Figure 2 The following is a schematic diagram of the end face structure of the present invention, as shown in the figure: A power split type reducer of this embodiment includes a reducer housing 8, an input gear 1, at least one first planetary gear 2 meshing with the input gear 1, a first gear ring 3 meshing with each of the first planetary gears 2 and rotatably supported on the reducer housing 8 about its own axis, and a planet carrier 4 arranged coaxially with the input gear 1 and supporting the rotation of each of the first planetary gears 2; it also includes: a second-stage small sun gear 5, coaxially and fixedly connected to the first gear ring 3, forming a double gear with the first gear ring 3; at least one idler gear 6, each of the idler gears 6 meshing with the second-stage small sun gear 5, and the rotation axis of each of the idler gears 6 being fixed to the reducer housing 8; a second gear ring 7, which is an internal gear ring, internally meshing with each of the idler gears 6; the second gear ring 7 is fixedly connected to the planet carrier 4, forming an output component, and the output component is rotatably supported on the reducer housing 8.

[0034] The input gear 1, first planetary gears 2, first ring gear 3, and planet carrier 4 form a planetary gear train, while the second-stage sun gear 5, idler gear 6, and second ring gear 7 form a fixed-axis gear train. Together, they form a composite transmission mechanism. Input power is split into a first path and a second path via the input gear 1 and each of the first planetary gears 2. The first path power is transmitted and output via the planet carrier 4, while the second path power is transmitted and output via the first ring gear 3, second-stage sun gear 5, each of the idler gears 6, and second ring gear 7. The two paths converge at the output component and are then output by the output component. By splitting the input power into two paths, the load on each individual transmission component is reduced, thereby achieving high torque transmission in a smaller volume and weight, and increasing power density.

[0035] In this embodiment, an input shaft is also included. The input shaft is coaxially and fixedly connected to the input gear 1 via a key connection. The input end of the input shaft is drive-connected to the output shaft of a power source such as a motor shaft. The input shaft is a hollow shaft with a first hollow channel running through it along the axial direction. A second hollow channel running through it along the axial direction is provided at the central axis of the planetary carrier 4. The second hollow channel and the first hollow channel are coaxially arranged, and together they form a continuous path through both the input and output ends of the reducer. Cables or fluid pipelines can pass through the center of the reducer via the first and second hollow channels to meet the wiring requirements inside the robot joints. The hollow structure also reduces the weight of the reducer, which is beneficial for improving power density.

[0036] In this embodiment, the input gear 1 is disposed inside the planetary carrier 4 and is arranged coaxially with the planetary carrier 4. The first planetary gear 2 is arranged circumferentially between the input gear 1 and the first gear ring 3, and meshes with both the input gear 1 and the first gear ring 3. The input gear 1 is built into the internal space of the planetary carrier 4, which integrates the input-side components in axial height, shortens the axial dimension of the input side, and makes the structure compact, which is beneficial for applications in space-constrained situations.

[0037] In this embodiment, there are multiple first planetary gears 2 and multiple idler gears 6. The multiple first planetary gears 2 constitute a first planetary gear set, and the multiple idler gears 6 constitute an idler gear set. The first planetary gear set is located on one side of the planet carrier 4 along the axial direction, i.e., the input side; the idler gear set is located on the other side of the planet carrier 4 along the axial direction, i.e., the output side; the first planetary gear set and the idler gear set are respectively located on opposite sides of the planet carrier 4 along the axial direction. In this way, the planetary gear train and the fixed-axis gear train are respectively arranged on both sides of the planet carrier 4, and the transmission components are highly integrated in the axial space, which reduces the axial dimension of the reducer while realizing power splitting.

[0038] In this embodiment, the number of first planetary gears 2 is three or more, and the number of idler gears 6 is three or more, with both the first planetary gears 2 and the idler gears 6 evenly distributed along the circumference. This evenly distributed multi-point meshing structure distributes the load evenly among multiple meshing pairs, reducing the stress level on individual gears and decreasing tooth surface contact stress and bending stress. Simultaneously, the evenly distributed arrangement ensures a symmetrical distribution of forces at each meshing point, which is beneficial for improving the stress state of the planetary carrier 4 and the output components, thereby increasing load-bearing capacity, transmission smoothness, and service life.

[0039] In this embodiment, the first gear ring 3 and the second-stage small sun gear 5 are integrally formed or fixed by a key connection. They are coaxially arranged and rotate synchronously, forming a double gear. The double gear is supported on the housing by bearings and can rotate around its own axis. When integrally formed, the first gear ring 3 and the second-stage small sun gear 5 are made as a single part, reducing assembly steps and improving coaxial accuracy. When keyed, the two parts are machined separately and then assembled, facilitating separate material selection and processing. The first gear ring 3 meshes with the first planetary gear 2, and the second-stage small sun gear 5 meshes with the idler gear 6. The second power path is transmitted from the planetary gear train to the fixed-axis gear train via the double gear.

[0040] In this embodiment, the second gear ring 7 and the planet carrier 4 are integrally formed, meaning the planet carrier 4 and the second gear ring 7 are the same component, constituting the output component. The output component is fixedly connected to other output components and forms a rotatable connection with the support frame through bearings. By making the second gear ring 7 and the planet carrier 4 into the same component, the first power path and the second power path can be directly combined on the same component. There is no need to set a connecting shaft between the planet carrier 4 and the output component, nor is there a need to set an output gear on the output shaft. This reduces the number of parts and axial series links, resulting in a compact structure and high overall rigidity of the output component.

[0041] In this embodiment, the first planetary gear 2 and the idler gear 6 can use gears of the same specification, the first ring gear 3 and the second ring gear 7 can use ring gears of the same specification, and the input gear 1 and the second-stage small sun gear 5 can use gears of the same specification. Since the second ring gear 7 and the planet carrier 4 are the same component, the rotational speed at which the second power is transmitted to the second ring gear 7 must be consistent with the rotational speed of the planet carrier 4. The aforementioned gear relationship of the same specification can satisfy this rotational speed matching condition, ensuring that the two power paths can be properly combined. At the same time, the uniform specification reduces the types of parts, lowers manufacturing costs and assembly difficulty, and facilitates mass production.

[0042] In this embodiment, the tooth profiles of the input gear 1, the first planetary gear 2, the first gear ring 3, the second-stage sun gear 5, the idler gear 6, and the second gear ring 7 can all be selected from various tooth profiles such as involute tooth profile and circular arc tooth profile. Among them, the involute tooth profile has smooth meshing, large overlap, and mature processing technology, which is beneficial to reducing vibration and noise during transmission and ensuring transmission accuracy and smoothness.

[0043] In this embodiment, the reducer housing 8 includes a casing and a support frame, both of which are integral parts of the reducer housing 8 and are fixedly installed. The gear shafts of each idler wheel 6 are fixed to the support frame. Each idler wheel 6 is rotatably mounted on its corresponding gear shaft via bearings and bushings. The idler wheel 6 rotates only around its own axis and does not revolve around the input gear 1. The gear shafts are fixedly supported by the support frame, providing good support rigidity. The output component is rotatably connected to the support frame via bearings; the double gear is supported by bearings on the casing. This support arrangement ensures reliable positioning and high support rigidity for each rotating component, which helps reduce stress deformation and improves transmission accuracy and operational stability.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A power split-type reducer, comprising a reducer housing, an input gear, at least one first planetary gear meshing with the input gear, a first gear ring meshing with each of the first planetary gears and rotatably supported on the reducer housing about its own axis, and a planet carrier coaxially arranged with the input gear and supporting the rotation of each of the first planetary gears, characterized in that: Also includes: The second-stage small sun gear is coaxially and fixedly connected to the first gear ring, forming a double gear with the first gear ring; At least one idler gear, each of the idler gears meshing with the second-stage small sun gear, and the rotation axis of each of the idler gears being fixed to the reducer housing; The second gear ring is an internal gear ring that meshes with each of the idler gears; the second gear ring is fixedly connected to the planetary carrier to form an output component, which is rotatably supported on the reducer housing; The input power is split into a first power path and a second power path via the input gear and each of the first planetary gears. The first power path is transmitted to the output component via the planetary carrier, and the second power path is transmitted to the output component via the first gear ring, the second stage small sun gear, each of the idler gears, and the second gear ring. The two power paths are combined in the output component and then output by the output component.

2. The power split reducer according to claim 1, characterized in that: It also includes an input shaft, which is coaxially and fixedly connected to the input gear via a key connection; the input shaft is a hollow shaft with a first hollow channel running through it along the axial direction; a second hollow channel running through it along the axial direction is provided at the central axis of the planetary carrier, and the second hollow channel is coaxially arranged with the first hollow channel.

3. The power split reducer according to claim 1, characterized in that: The input gear is located inside the planetary carrier.

4. The power split reducer according to claim 1, characterized in that: There are multiple first planetary gears and multiple idler gears. The multiple first planetary gears constitute a first planetary gear set, and the multiple idler gears constitute an idler gear set. The first planetary gear set and the idler gear set are respectively disposed on opposite sides of the planet carrier along the axial direction.

5. The power split reducer according to claim 4, characterized in that: The number of the first planetary gears is three or four, the number of the idler gears is three or four, and both the first planetary gears and the idler gears are evenly distributed along the circumference.

6. The power split reducer according to claim 1, characterized in that: The first gear ring and the second stage small sun gear are integrally formed or fixed by key connection.

7. The power split reducer according to claim 1, characterized in that: The second gear ring and the planet carrier are integrally formed.

8. The power split reducer according to claim 1, characterized in that: The first planetary gear and the idler gear can be gears of the same specification, the first gear ring and the second gear ring can be gear rings of the same specification, and the input gear and the second stage small sun gear can be gears of the same specification.

9. The power split reducer according to claim 1, characterized in that: The reducer housing includes a housing and a support frame; the gear shafts of each idler wheel are fixed to the support frame, and each idler wheel is rotatably mounted on the corresponding gear shaft through bearings and bushings; the output component is rotatably connected to the support frame through bearings; the double gear is supported on the housing through bearings.

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