Integrated duplex planet wheel hub reduction gear

Abstract

The invention discloses an integrated duplex planet wheel hub reduction gear which comprises a duplex planet wheel, the duplex planet wheel comprises a large planet wheel and a small planet wheel, a sun wheel is meshed with the large planet wheel, an inner gear ring is meshed with the small planet wheel, a first deep groove ball bearing close to the inner gear ring is matched with a hub, and a second deep groove ball bearing close to the inner gear ring is matched with the hub. The hub and the planet carrier are integrally designed, torque is directly output to a wheel, and the rigidity of the planet carrier is enhanced through the design of an annular reinforcing rib. Interference fit of a traditional split type planet wheel is omitted, the large planet wheel and the small planet wheel are integrated into the integrally-machined duplex planet wheel gear shaft, through the unique integrated duplex planet gear design, high-speed power of a motor is effectively converted into high-torque low-speed output, and the output speed of the motor is increased. And meanwhile, light weight and high efficiency of the speed reducer are realized. And by adopting a high-strength material and an optimized heat dissipation design, the reliability and durability in an extreme racing car environment are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of power transmission systems for high-performance racing cars, and particularly to an integrated dual planetary gear wheel side reducer. Background Art

[0002] In the field of modern electric racing car competitions, the reducer, as a key part of the power transmission system, is responsible for converting the high-speed torque of the motor into the low-speed high-torque output of the wheel axle. Traditional reducers mostly adopt multi-stage gears or traditional planetary gear systems. For example, the wheel side reducer disclosed in Patent No. CN202410768045.7 uses a split planetary gear assembly and a bracket structure connected by bolts. Although it can complete speed conversion, it has disadvantages such as large volume, complex structure, and large energy loss. For Formula E racing cars, these problems are even more serious. Although direct motor drive can reduce energy loss and improve response speed, it increases the unsprung mass at the wheel side, affecting the vehicle's handling stability. Therefore, there is an urgent need for a new type of reducer design that can reduce volume and weight while improving the overall mechanical efficiency and response speed. Summary of the Invention

[0003] The purpose of the present invention is to provide an integrated dual planetary gear wheel side reducer to meet the power matching requirements of the vehicles participating in the Formula E race, especially in terms of volume, weight, mechanical efficiency, and response speed.

[0004] An integrated dual planetary gear wheel side reducer includes:

[0005] A sun gear, which is connected to the motor shaft and serves as a component for inputting torque;

[0006] An internal gear ring, which has an interference fit with the column excavation;

[0007] A dual planetary gear, canceling the interference fit of the traditional split planetary gear, integrating the large planetary gear (high-speed planetary gear) and the small planetary gear (low-speed planetary gear) into an integrally machined dual planetary gear shaft. It is connected to the wheel hub and the secondary planetary carrier through a light shaft. The dual planetary gear includes a large planetary gear and a small planetary gear. The sun gear meshes with the large planetary gear, and the internal gear ring meshes with the small planetary gear. The first deep groove ball bearing close to the internal gear ring cooperates with the wheel hub. The wheel hub and the planetary carrier are integrally designed to directly output torque to the wheel, and the planetary carrier is designed with a ring-shaped reinforcing rib to enhance stiffness;

[0008] A secondary planetary carrier, which cooperates with the column and the wheel hub through a second deep groove ball bearing.

[0009] As a further technical solution of the present invention, it further includes a column oil seal, which is embedded at the connection between the wheel hub and the column to prevent oil leakage.

[0010] As a further technical solution of the present invention, the transmission ratio of the reducer is 13.0 - 13.5.

[0011] As a further technical solution of the present invention, one end of the sun gear shaft is provided with a spline hole and is connected to the motor shaft.

[0012] As a further technical solution of the present invention, the optical axis passes through the gear hole and is connected to the double planetary gear. At the same time, the optical axis is connected to the hub round hole and the secondary planet carrier round hole for axial limit of the double planetary gear; the double gear hole shaft and the bearing are designed in the end face holes of the gear, and are matched with the pin column and the needle roller bearing HK0913, and both ends are embedded in the planet carrier.

[0013] As a further technical solution of the present invention, the large planet gear adopts a web-type structure with hole punching design to reduce the moment of inertia; for convenient processing, disassembly and assembly, a split secondary planet carrier structure is proposed, and three M6 ordinary bolts are used to pass through the bolt holes of the secondary planet carrier and connect with the bolt holes on the end faces of the three struts of the hub to fix the secondary planet carrier; in order to reduce the stress concentration at the root of the hub, the side of the hub strut adopts an arc transition design.

[0014] As a further technical solution of the present invention, the sun gear, the internal gear ring and the double planetary gear are made of 20CrMnTi material.

[0015] As a further technical solution of the present invention, the planet carrier and the column are made of 7075 aluminum alloy material.

[0016] The beneficial effects achieved by the present invention:

[0017] The present invention is small in size and light in weight: the interference fit between the traditional large and small planet gears is cancelled, and through reasonable gear design and structural layout, the lightweight and miniaturization of the reducer are realized. High mechanical efficiency: an integrated design and a 2Z-X (B) type planetary gear transmission structure are adopted to improve the transmission efficiency. Fast response speed: the structure is compact, reducing energy loss and improving the response speed. Easy to maintain: the structure design is reasonable, facilitating disassembly, assembly and maintenance. Structure and material optimization: by using high-strength aluminum alloy and special hardening treatment, the structural strength of the reducer is optimized to ensure stability and durability during high-speed operation. Description of the Drawings

[0018] Figure 1 It is a schematic diagram of the overall structure of an integrated double planetary gear wheel side reducer.

[0019] Figure 2 It is a parameter characteristic curve diagram of the motor used in the Formula E racing car.

[0020] Figure 3 It is an analysis diagram of the straight-line acceleration, durability and efficiency results under different transmission ratios.

[0021] Figure 4 It is the disassembly modeling diagram of the wheel side reducer.

[0022] Figure 5 It is the overall modeling diagram of the wheel side reducer.

[0023] Figure 6 It is the simulation verification diagram of the hub of the wheel side reducer.

[0024] Figure 7 It is the sectional view of the wheel side reducer from the B-B perspective.

[0025] Figure 8 It is the sectional view of the wheel side reducer from the A-A perspective.

[0026] Figure 9 It is the sectional view of the wheel side reducer from the C-C perspective.

[0027] Figure 10 It is the sectional view of the wheel side reducer from the D-D perspective.

[0028] Annotation of reference numerals in the drawings: 1 - hub, 2 - column, 3 - column oil seal, 4 - first deep groove ball bearing, 5 - smooth shaft, 6 - second deep groove ball bearing, 7 - M6 ordinary bolt, 8 - sun gear, 9 - double planetary gear, 10 - internal gear ring, 11 - drain plug, 12 - secondary planetary carrier. Detailed implementation manners

[0029] The following combines specific drawings to introduce and describe the technical solution of the present invention in detail.

[0030] Please refer to Figures 1 to 10 , the embodiment of the present invention provides an integrated double planetary gear wheel side reducer, including:

[0031] A sun gear 8, which is connected to the motor shaft and serves as a component for inputting torque;

[0032] An internal gear ring 10, which is in interference fit with the dug hole of the column 2;

[0033] A double planetary gear 9, canceling the interference fit of the traditional split planetary gear, integrating the large planetary gear and the small planetary gear into an integrally machined double planetary gear shaft; it is connected to the hub 1 and the secondary planetary carrier 12 through a smooth shaft 5, the double planetary gear 9 includes a large planetary gear and a small planetary gear, the sun gear 8 meshes with the large planetary gear, the internal gear ring 10 meshes with the small planetary gear, the first deep groove ball bearing 4 close to the internal gear ring 10 cooperates with the hub 1, and the hub 1 and the planetary carrier are integrally designed to directly output torque to the wheel;

[0034] A secondary planetary carrier 12, which cooperates with the column 2 and the hub 1 through a second deep groove ball bearing 6.

[0035] In this embodiment, it further includes a column oil seal 3, which is embedded at the connection between the wheel hub 1 and the column 2 to prevent oil leakage.

[0036] In this embodiment, one end of the sun gear shaft is provided with a spline hole and is connected to the motor shaft.

[0037] In this embodiment, the optical axis 5 passes through the gear hole and is connected to the double planetary gear. At the same time, the optical axis 5 is connected to the circular hole of the wheel hub 1 and the circular hole of the secondary planet carrier 12 to axially limit the double planetary gear 9; the double gear hole shaft and the bearing are designed in the holes at both ends of the gear, and are matched with the pin column and the needle roller bearing HK0913, and both ends are embedded in the planet carrier.

[0038] In this embodiment, to ensure good meshing between the double planetary gear 9 and the internal gear ring 10 and the sun gear 8, the present invention will increase the tooth width of the gear; the large planetary gear adopts a web type structure with holes drilled to reduce the moment of inertia; for convenient processing and disassembly, a split secondary planet carrier structure is proposed. The inner hole of the secondary planet carrier has a clearance fit with the three struts of the wheel hub planet carrier. Three M6 ordinary bolts 7 are inserted into the bolt holes of the secondary planet carrier 12 and connected to the bolt holes on the end faces of the three struts of the wheel hub 1 to fix the secondary planet carrier 12; to reduce the stress concentration at the root of the wheel hub, the side of the strut of the wheel hub 1 adopts an arc transition design.

[0039] In this embodiment, the input end of the reducer is connected to a motor, and the output end is connected to a drive wheel, which is used to convert the high-speed power of the motor into low-speed power output with high torque. It also includes a motor end cover, which is made of 7075 aluminum alloy. The motor end cover is connected to the column end face with a plug bolt, and the upper and lower drain plugs 11 are installed, and lubricating oil is injected.

[0040] In this embodiment, the transmission ratio of the reducer is 13.0 - 13.5. The reducer of the present invention is a 2Z-X(B) type planetary gear transmission structure, that is, an NW type planetary reducer, and its transmission structure is as Figure 1 shown. By calculating the tooth matching and related gear parameters through MATLAB, the column radial dimension is 110 mm, meeting the design goal.

[0041] Appendix Figure 1 The description of the letter parameters in it is shown in Table 1:

[0042] Table 1

[0043]

[0044] The symbol description is shown in Table 2:

[0045] Table 2

[0046]

[0047] Determination of the transmission ratio:

[0048] With the optimization goal of accelerating performance, first analyze the performance parameters of the AMK DD5-14-10-POW-18600-B5 servo motor used in the 12th-generation cloud electric vehicle, such as Figure 2 shown, the symbol explanations in the figure are shown in Table 3:

[0049] Table 3

[0050]

[0051] The peak torque of this motor is 21 N*m, and the peak speed is 18000 rpm. Before the speed reaches about 12000 rpm, the peak torque decreases slowly as a first-order linear function with the increase of speed, and the peak power increases uniformly as a first-order function with the increase of speed; after exceeding 12000 rpm, the torque reduction speed accelerates while the power increase speed slows down. After comprehensively considering the vehicle parameters and road conditions, establish a tire model and perform the Magic Formula

[0052] ;

[0053] After fitting, perform simulations to respectively obtain the 75m straight-line acceleration, the time consumption and power consumption in the endurance race (Xiangyang endurance track in 20 years) under different transmission ratios, as Figure 3 shown. It can be seen from the figure that a better endurance race time consumption and power consumption can be obtained when the transmission ratio is between 13.0 - 13.5. Therefore, determine the optimal transmission ratio range of 13.0 - 13.5.

[0054] Calculation of gear pairing and meshing parameters

[0055] The expected design conditions of the four-motor in-wheel reducer are: on the premise of meeting reliability, the radial layout space of the column is less than 100 mm, and the estimated radial diameter is less than 130 mm.

[0056] ;

[0057] ;

[0058] ;

[0059] ;

[0060] Tooth number conditions for NW-type planetary gear transmission:

[0061] ① Transmission ratio condition: ;

[0062] ② Center distance condition: ;

[0063] ③ Assembly condition: ;

[0064] Among them, is the pitch circle diameter of the high-speed stage gear pair, is the pitch circle diameter of the low-speed stage gear pair, A is the transmission ratio of the high-speed stage gear, B is the transmission ratio of the low-speed stage gear, i is the total transmission ratio, P is the product of the transmission ratios of the high and low speed stages, K is the pitch circle diameter of the sun gear, and N is a positive integer.

[0065] The relationship between the radial dimension and the parameters of the NW type planetary gear drive is discussed as follows: Set the pitch circle diameter of the high-speed stage gear pair as ; Set the pitch circle diameter of the low-speed stage gear pair as ; It can be known from actual design that is often greater than , so it plays a dominant role in the influence of the radial dimension. Set , ; Simplify the radial dimension to several key values , i, , , B. After arranging the above formulas, it can be obtained that the radial dimension is in a direct proportional relationship with the module , the number of teeth of the sun gear and is in an inverse proportional relationship with the transmission ratio B of the low-speed stage, and further arrange to obtain the range of B.

[0066] The limit of the second-stage transmission ratio of the NW type planetary reducer is generally not greater than 4.5. Therefore, after given relevant parameters such as the transmission ratio, radial dimension requirements, and module, the value of the second-stage transmission ratio is continuously approximated to 4.5. To effectively achieve the lightweight requirement of the wheel-side reducer, the tooth matching and related gear parameters will be calculated by MATLAB, and the column radial dimension is obtained as 110 mm, meeting the expected design goal that the column radial dimension is less than 130 mm.

[0067] The specific parameters of the gears calculated by the reducer are shown in Table 4:

[0068] Table 4

[0069]

[0070] In this embodiment, the sun gear 8, the internal gear ring 10 and the double planetary gear 9 are made of 20CrMnTi material, carburized and quenched, and processed by slow wire cutting.

[0071] In this embodiment, the planet carrier and the column 2 are made of 7075 aluminum alloy material, hard anodized, and processed by CNC using a three-axis machine tool.

[0072] The auxiliary planet carrier 12 is used for power transmission, which simplifies the mechanism, reduces the mass and improves the transmission efficiency at the same time. The ring gear and the column are in large interference fit to achieve the load sharing effect, and the annular reinforcing ribs are added to the planet carrier struts to reduce stress concentration, effectively improving the reliability of the wheel side reducer. Using the ANSYS software, a torque of 3780 * 26 * 3 = 294840 N·mm is applied to the auxiliary planet carrier 12, and at the same time, the positions of the four pin holes of the hub 1 are fixed. The specific simulation results are as Figure 6 shown. It can be seen from the figure that the maximum stress is 288.19 MPa, which is within the yield limit of 455 MPa of 7075 aluminum alloy, verifying the reliability of the design.

[0073] It should be noted that in this article, the term "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent in such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, article or device including that element.

[0074] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. An integrated double planetary gear reducer, characterized in that: include: A sun gear connected to the motor shaft as a component for inputting torque; The inner gear ring has an interference fit with the hole of the column; The double-linked planetary gear eliminates the interference fit of the traditional split planetary gear and integrates the large planetary gear and the small planetary gear into an integrally processed double-linked planetary gear shaft; it is connected to the wheel hub and the auxiliary planetary carrier through an optical shaft, the double-linked planetary gear includes the large planetary gear and the small planetary gear, the sun gear meshes with the large planetary gear, the inner gear ring meshes with the small planetary gear, the first deep groove ball bearing close to the inner gear ring cooperates with the wheel hub, the wheel hub and the planetary carrier are designed as an integrated whole, and the torque is directly output to the wheel, and the planetary carrier is enhanced in rigidity by an annular reinforcing rib design; The auxiliary planet carrier cooperates with the column and the wheel hub through a second deep groove ball bearing.

2. The integrated double planetary gear reducer according to claim 1, characterized in that: It also includes a column oil seal, which is embedded in the connection between the wheel hub and the column to prevent oil leakage.

3. The integrated double planetary gear reducer according to claim 1, characterized in that: One end of the sun gear shaft is provided with a spline hole, which is connected to the motor shaft.

4. The integrated double planetary gear reducer according to claim 1, characterized in that: The optical axis passes through the gear hole and is connected to the double planetary gear. At the same time, the optical axis is connected to the circular hole of the hub and the circular hole of the auxiliary planetary carrier to limit the axial position of the double planetary gear. The double gear hole shaft and bearings are designed in the two end holes of the gear, and the pin is matched with the needle roller bearing HK0913, and the two ends are embedded in the planetary carrier.

5. The integrated double planetary gear reducer according to claim 1, characterized in that: The large planetary wheel adopts a web-type structure with a punched hole design and a split auxiliary planetary carrier structure. Three M6 ordinary bolts are inserted into the bolt holes of the auxiliary planetary carrier and connected with the bolt holes on the end faces of the three pillars of the hub to fix the auxiliary planetary carrier. The side of the hub support adopts a curved transition design.

6. The integrated double planetary gear reducer according to claim 1, characterized in that: The sun gear, the inner gear ring and the double planetary gear are made of 20CrMnTi material.

7. The integrated double planetary gear reducer according to claim 1, characterized in that: The planet carrier and column are made of 7075 aluminum alloy.

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