Four-wheel independent hub reduction driving system suitable for formula car

Abstract

The invention is applicable to the technical field of automobile transmission, and provides a four-wheel independent hub reduction driving system applicable to formula cars, which comprises a hub connected with a rim through a rim connecting part, a brake disc connected with the outer side of the hub through a brake disc connecting part, and a planetary gear system connected with the hub through a planetary gear. And the planetary gear system is arranged in a working space arranged in the wheel edge. The transmission path integration degree of the system is high, the structure simplification degree is high, and the adopted material strength is enough. And only radial positioning of the planet gear is restrained, axial movement is allowed, and gear teeth of the planet gear cannot be broken under the condition that the lateral acceleration is 2.0 g. According to the system, a clutch, a gearbox, a differential mechanism, a half shaft and other components of a traditional driving system are abandoned, complex components of a transmission system are greatly simplified, and meanwhile light weight of the transmission system of the racing car is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile transmission, and in particular relates to a four-wheel independent wheel-side reduction drive system suitable for formula racing cars. Background Art

[0002] Formula SAE (FSAE) was founded by the Society of Automotive Engineers (SAE) in 1978. The China Society of Automotive Engineers (SAE) held its first China Student Electric Formula E competition in Shanghai in 2015. This competition is a vehicle design and manufacturing competition for teams of university students majoring in automotive engineering or related fields. Each participating team, in accordance with the competition rules, has one year to design and manufacture a small, single-seater recreational racing car that demonstrates superior acceleration, braking, and handling.

[0003] The competition aims to provide college students with opportunities for practice and training, and to discover, tap and cultivate future talents in China's automotive industry, especially in the field of new energy vehicles.

[0004] Germany has a particularly mature track record in this discipline. In 2010, at the inaugural German tram race, the University of Stuttgart employed dual rear-wheel motors, equipped with a single-stage planetary reducer as the main reducer. In 2012, the Delft University of Technology pioneered the use of a four-motor plus wheel-mounted reducer, demonstrating a clear performance advantage in that year's competition. Today, this combination has become the mainstream choice in European competitions. In the 2019 German race, four-wheel independent drive vehicles accounted for over 50% of the total number of trams.

[0005] However, China's Formula E racing drive system design is still immature. Most domestic universities utilize dual rear-wheel motors, single-motor chain drives, and belt drives. Tongji University pioneered a four-motor + wheel-side drive system in 2016, but four-motor drive systems are rarely used by domestic teams. These older drive systems fail to fully realize the potential of Formula E racing in terms of acceleration and maximum speed, fail to maximize the performance of electric vehicles, and fail to meet the development needs of the university Formula E competition. Summary of the Invention

[0006] The purpose of the embodiments of the present invention is to provide a four-wheel independent wheel reduction drive system suitable for formula racing cars, aiming to solve the problems raised in the above background technology.

[0007] The embodiment of the present invention is implemented as follows: a four-wheel independent wheel-rim reduction drive system suitable for a formula racing car includes a wheel rim, wherein the wheel rim is connected to a wheel rim via a rim connecting portion, and the outer side of the wheel rim is connected to a brake disc via a brake disc connecting portion; and further includes:

[0008] A planetary gear system, the planetary gear system being installed in a working space provided inside the wheel rim, the planetary gear system comprising a front planet carrier, a rear planet carrier, planet shafts, planetary gears, a sun gear and a ring gear;

[0009] One end of the planetary shaft is connected to the front planetary carrier, and the other end is connected to the rear planetary carrier. There are three planetary shafts, and the three planetary shafts are distributed in an annular array between the front planetary carrier and the planetary carrier. A planetary gear is installed on each planetary shaft; the small-toothed end of the planetary gear meshes with the ring gear, and the large-toothed end of the planetary gear meshes with the sun gear, and the two ends are respectively matched with the front planetary carrier and the rear planetary carrier;

[0010] The sun gear is stepped, with a smaller diameter on the tooth side, and is used to assemble the sun gear bearing. The outer side of the sun gear bearing is matched with the front planet carrier. The interior of the sun gear is provided with an internal spline, which is interference fit with the spline of the motor output shaft, and the sun gear is connected to the motor output shaft via a sun gear connecting bolt;

[0011] The front planet carrier and the rear planet carrier are connected by planet carrier connecting bolts. The front planet carrier is provided with three triangular prism-shaped bosses in a circle. The upper surfaces of the bosses are completely in contact with the rear planet carrier, and the centers of the bosses are provided with center holes for matching the planet carrier connecting bolts. The boss holes are provided with a first mounting groove at one end near the rear planet carrier. A steel sleeve is installed in the first mounting groove, and one end of the steel sleeve is installed in the first mounting groove, and the other end of the steel sleeve is installed in the second mounting groove provided in the rear planet carrier. The rear portion of the front planet carrier is also provided with six pin holes distributed concentrically. One end of a metal pin cooperates with the pin hole, and the other end cooperates with the pin hole of the corresponding steering knuckle.

[0012] A rear oil seal is installed on the inner side of the wheel rim, and the outer side of the wheel rim is connected to the cover plate, and an O-ring mounting groove for mounting an O-ring is provided on the connecting side. The depth of the O-ring mounting groove is smaller than the wire diameter of the O-ring, and the remaining part is squeezed and matched with the cover plate to form a sealed space. A breather valve is installed at the axis of the cover plate through a threaded hole.

[0013] A further technical solution is that the rear planetary carrier is installed on the inner side of the rear planetary carrier bearing, and the outer side of the rear planetary carrier bearing is installed in a first bearing mounting groove set in the working space; the front planetary carrier is installed on the inner side of the front planetary carrier bearing, and the outer side of the front planetary carrier bearing is installed in a second bearing mounting groove set in the working space.

[0014] A further technical solution is that a gear ring mounting groove is provided inside the wheel rim for fixing the gear ring, and six bolt holes and six pin holes are provided in the gear ring mounting groove, and the bolt holes and the pin holes are arranged concentrically and staggered, and the bolt holes and the bolts are fastened to limit the axial movement of the gear ring, and the pin holes and the metal pins cooperate to limit the radial movement of the gear ring.

[0015] A further technical solution is that the rim connection part has a planar structure on the side that contacts the spokes and fits the spokes, and the non-contact side has an arc-shaped structure; the rim connection part is provided with twelve extended ear pieces, each of which is provided with a connecting hole, the contact side of the connecting hole is a threaded hole for bolt fixing, and the rear side is a square groove for limiting the rotation of the horse head bolt connecting the spokes.

[0016] A further technical solution is that the connection method between the wheel rim and the cover plate is the same as the connection method between the wheel rim and the spoke, six extended ear pieces extend from the outside of the wheel rim, each extended ear piece is distributed in an array with the center of the reducer as the axis, and the extended ear pieces are connected to the wheel rim through the cover plate connecting bolts.

[0017] A further technical solution is that the distance between the brake disc connection part and the rim connection part is greater than the thickness of the brake caliper; the brake disc connection part is provided with six extended ears, each of which is provided with a threaded hole and is connected to the brake disc by bolts; and the distance from the brake disc connection part to the wheel edge is less than the distance from the rim connection part to the wheel edge.

[0018] According to a further technical solution, the planetary shaft is made of 40Cr, and the shaft portion of the planetary shaft is a hollow structure.

[0019] According to a further technical solution, six trapezoidal weight-reducing holes are provided at the rear of the front planetary carrier, and three trapezoidal weight-reducing holes are also provided at the rear planetary carrier.

[0020] According to a further technical solution, the material of the planetary gear is 20CrMnTi.

[0021] A further technical solution is that three trapezoidal grooves are provided at the upper end of the front planetary carrier, the small aperture part of the trapezoidal groove is used to fix the planetary shaft, and the large aperture part of the trapezoidal groove has a depth of 2mm and is used to place the first gear gasket and the second gear gasket.

[0022] According to a further technical solution, both the front and rear ends of the planetary wheels are provided with assembly grooves of a certain depth for assembling the first planetary wheel bearing and the second planetary wheel bearing.

[0023] According to a further technical solution, a weight-reducing hole is provided in the area where the large teeth end of the planetary gear is not subjected to stress.

[0024] Embodiments of the present invention provide a four-wheel independent wheel-end reduction drive system suitable for Formula One racing cars. This system features a highly integrated transmission path, a simplified structure, and strong materials. Only radial positioning of the planetary gears is constrained, while axial movement is permitted, preventing tooth breakage under 2.0g lateral acceleration. This system eliminates the clutch, gearbox, differential, and axle shafts of traditional drive systems, significantly simplifying the complex components of the transmission system while achieving lightweighting. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A cross-sectional view of a four-wheel independent wheel reduction drive system suitable for a formula car provided by an embodiment of the present invention;

[0026] Figure 2 A disassembled schematic diagram of a four-wheel independent wheel reduction drive system suitable for a formula car provided by an embodiment of the present invention;

[0027] Figure 3 An axonometric diagram of a four-wheel independent wheel reduction drive system suitable for a formula car provided by an embodiment of the present invention;

[0028] Figure 4 A schematic diagram of the disassembly of the planetary gear movement portion of a four-wheel independent wheel reduction drive system suitable for a formula car provided by an embodiment of the present invention;

[0029] Figure 5 A schematic diagram of the disassembly of a planetary gear system in a four-wheel independent wheel reduction drive system suitable for a formula racing car provided by an embodiment of the present invention.

[0030] In the accompanying drawings: 1-breathable valve; 2-cover plate connecting bolt; 3-cover plate; 4-planet carrier connecting bolt; 5-rear planet carrier bearing; 6-planetary gear system; 7-front planet carrier bearing; 8-wheel rim; 9-rear oil seal; 10-rear planet carrier; 11-ring gear; 12-sun gear bearing; 13-sun gear connecting bolt; 14-sun gear; 15-front planet carrier; 16-first gear gasket; 17-first planet gear bearing; 18-planet gear; 19-second planet gear bearing; 20-second gear gasket; 21-planet shaft; 22-wheel rim connection part; 23-brake disc connection part. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0032] The specific implementation of the present invention is described in detail below with reference to specific embodiments.

[0033] like Figure 1-Figure 5 FIG. 1 shows a four-wheel independent wheel-rim reduction drive system for a formula racing car according to an embodiment of the present invention, comprising a wheel rim 8 connected to a wheel rim via a rim connection portion 22 , and an outer side of the wheel rim 8 connected to a brake disc via a brake disc connection portion 23 ; and further comprising:

[0034] A planetary gear system 6 is installed in a working space provided inside the wheel rim 8, and includes a front planet carrier 15, a rear planet carrier 10, planet shafts 21, planetary gears 18, a sun gear 14, and a ring gear 11;

[0035] One end of the planetary shaft 21 is connected to the front planetary carrier 15, and the other end is connected to the rear planetary carrier 10. There are three planetary shafts 21, and the three planetary shafts 21 are distributed in a ring between the front planetary carrier 15 and the planetary carrier 10. A planetary gear 18 is mounted on each planetary shaft 21. The planetary gear 18 is a 1.5-stage planetary gear, with its small-tooth end meshing with the ring gear 11 and its large-tooth end meshing with the sun gear 14. The two ends are respectively engaged with the front planetary carrier 15 and the rear planetary carrier 10.

[0036] The sun gear 14 is stepped, with a smaller diameter on the tooth side, and is used to assemble the sun gear bearing 12. The outer side of the sun gear bearing 12 is matched with the front planet carrier 15. The sun gear 14 is internally provided with an internal spline, which is interference fit with the motor output shaft spline. The sun gear 14 is connected to the motor output shaft via the sun gear connecting bolts 13.

[0037] The front planet carrier 15 and the rear planet carrier 10 are connected by planet carrier connecting bolts 4. Three triangular prism-shaped bosses are arranged in a circle on the front planet carrier 15. The edges of the bosses are replaced with rounded corners to improve the stress stability. The upper surface of the boss is completely in contact with the rear planet carrier 10, and a center hole for matching the planet carrier connecting bolt 4 is provided at the center of the boss; a first mounting groove is provided at one end of the boss hole close to the rear planet carrier 10, and a steel sleeve is installed in the first mounting groove, and one end of the steel sleeve is installed in the first mounting groove, and the other end of the steel sleeve is installed in the second mounting groove opened on the rear planet carrier 10. The radial displacement of the front planet carrier 15 and the rear planet carrier 10 is limited by the steel sleeve and the planet shaft 21, thereby alleviating the radial stress pressure on the planet shaft 21; the rear part of the front planet carrier 15 is also provided with six concentrically distributed pin holes, one end of the metal pin is matched with the pin hole, and the other end is matched with the corresponding pin hole of the steering knuckle, thereby limiting the relative displacement between the front planet carrier 15 and the steering knuckle.

[0038] A rear oil seal 9 is mounted on the inner side of the wheel rim 8. The outer side of the wheel rim 8 is connected to the cover plate 3, and an O-ring mounting groove is provided on the connecting side for mounting an O-ring. The depth of the O-ring mounting groove is less than the diameter of the O-ring, and the remaining portion is squeezed and fits with the cover plate to form a sealed space. A breather valve 1 is mounted at the axis of the cover plate 3 through a threaded hole. A rubber ring is installed inside the breather valve 1, which is squeezed when it fits with the cover plate 3 to form an effective seal.

[0039] In this embodiment of the present invention, the gear ratios between the sun gear, planetary gears, and ring gear in the planetary gear system are determined based on the designed maximum speed and maximum acceleration of the vehicle. The system requires gear lubrication oil to operate within the system, which is sealed. During operation, as the temperature and oil pressure rise, the gas pressure within the cavity increases. Breather valve 1 vents the air in a timely manner to balance the pressure and ensure stable operation.

[0040] The overall layout of the system is axisymmetric, and the axial integration of the reducer is achieved on the wheel side, making the four-motor drive system possible. This solves the problem of insufficient power in traditional electric formula racing cars. In formula competitions, it has faster acceleration and maximum speed, giving the car better dynamic performance and controllability.

[0041] like Figure 1 、 Figure 2 and Figure 4 As shown, as a preferred embodiment of the present invention, the rear planetary carrier is installed on the inner side of the rear planetary carrier bearing 5, and the outer side of the rear planetary carrier bearing 5 is installed in the first bearing mounting groove provided in the working space; the front planetary carrier 15 is installed on the inner side of the front planetary carrier bearing 7, and the outer side of the front planetary carrier bearing 7 is installed in the second bearing mounting groove provided in the working space.

[0042] As a preferred embodiment of the present invention, a gear ring mounting groove is provided inside the wheel rim 8 for fixing the gear ring 11 to prevent relative movement between the gear ring 11 and the wheel rim 8. Six bolt holes and six pin holes are provided in the gear ring mounting groove. The bolt holes and the pin holes are concentrically and staggeredly arranged to ensure that the wheel rim is uniformly stressed. The bolt holes and bolts are tightened to limit the axial movement of the gear ring. The pin holes and the metal pins cooperate to limit the radial movement of the gear ring.

[0043] like Figure 1-Figure 3 As shown, as a preferred embodiment of the present invention, the rim connection portion 22 has a flat structure on the side in contact with the spokes, which fits the spokes, and an arc structure on the side not in contact with the spokes, so as to avoid interference with the brake caliper and ensure connection strength;

[0044] The rim connecting portion 22 is provided with twelve trapezoidal holes, the positions of which do not affect the structural strength and are used to reduce weight;

[0045] The rim connection portion 22 is provided with twelve extended ear pieces, each of which is provided with a connecting hole. The contact side of the connecting hole is a threaded hole for bolt fixing, and the rear side is a square groove for limiting the rotation of the horse head bolt connecting the spokes to facilitate the installation of the nut.

[0046] In a preferred embodiment of the present invention, the connection between the wheel rim 8 and the cover plate 3 is similar to the connection between the wheel rim 8 and the spokes. Six extension lugs extend from the outer side of the wheel rim 8. Each extension lug is arranged in an array around the center of the reducer to ensure uniform force on the cover plate. The extension lugs are connected to the wheel rim 8 via cover plate connecting bolts 2.

[0047] like Figure 1-Figure 3 As shown, as a preferred embodiment of the present invention, the distance between the brake disc connection part 23 and the rim connection part 22 is greater than the thickness of the brake caliper to avoid interference; six extended ears are provided on the brake disc connection part 23, each of which is provided with a threaded hole and is connected to the brake disc by bolts; at the same time, considering that the weight of the brake disc is greater than the weight of the tire, the brake disc connection structure has more stringent requirements on the force strength, so the distance from the brake disc connection part 23 to the wheel edge 8 is smaller than the distance from the rim connection part 22 to the wheel edge 8.

[0048] like Figure 1-Figure 3 As shown, as a preferred embodiment of the present invention, the planetary shaft 21 is made of 40Cr, which has a strength higher than that of aluminum alloy, to ensure the strength and stability of the planetary shaft 21 under various loads. The shaft portion of the planetary shaft 21 is a hollow structure, which achieves lightweight without affecting the stress strength of the shaft.

[0049] As a preferred embodiment of the present invention, the rear portion of the front planet carrier 15 is provided with six trapezoidal weight-reducing holes, and the rear planet carrier 10 is also provided with three trapezoidal weight-reducing holes, thereby achieving lightweighting without affecting strength.

[0050] As a preferred embodiment of the present invention, the planetary gear 18 is made of 20CrMnTi, which has high tooth surface strength and internal toughness, and is suitable for the working conditions of the gear.

[0051] As a preferred embodiment of the present invention, three trapezoidal grooves are provided at the upper end of the front planetary carrier 15. The small-aperture portion of the trapezoidal groove is deeper and is used to fix the planetary shaft 21, thereby ensuring the stability of the axial movement of the planetary gear 18. The large-aperture portion of the trapezoidal groove is very shallow, leaving a depth of 2 mm, for placing the first gear gasket 16 and the second gear gasket 20.

[0052] In the embodiment of the present invention, during the operation of the planetary gear 18, friction will occur with the front planetary carrier 15, causing wear, and the wear will be transferred to the interchangeable and low-cost gasket, thereby increasing the life of the front planetary carrier 15 and being economical. At the same time, the first gear gasket 16 and the second gear gasket 20 also limit the axial position of the planetary gear 18.

[0053] like Figure 5As shown, as a preferred embodiment of the present invention, the front and rear ends of the planetary gear 18 are provided with assembly grooves of a certain depth for assembling the first planetary gear bearing 17 and the second planetary gear bearing 19, thereby reducing the relative friction between the planetary gear 18 and the planetary shaft 21 and extending the life of the planetary shaft 21 and the planetary gear 18.

[0054] As a preferred embodiment of the present invention, the large tooth end of the planetary gear 18 is provided with a weight-reducing hole to eliminate the position not subject to stress, thereby achieving the effect of weight reduction without affecting the strength.

[0055] Working Principle: The sun gear 14 and the motor transmit power through a splined connection. The motor drives the sun gear 14 to rotate. The external bearing and spindle of the sun gear 14 ensure that the sun gear 14 is aligned with the center. The sun gear 14 meshes with the large teeth of the three planetary gears 18, driving the planetary gears 18 to rotate. The large and small teeth of the planetary gears 18 are coaxial and coextensive. The small teeth mesh with the ring gear 11, driving the ring gear 11 to rotate. The ring gear 11 is fixed to the wheel rim 8, and the wheel rim 8 rotates with the ring gear 11. The outside of the wheel rim 8 is fixed to the tire via twelve horse-head bolts, thereby driving the tire. At the same time, the outside of the wheel rim 8 is bolted to the brake disc, and the brake caliper is fixed to the steering knuckle. When braking, the brake pads hydraulically lock the brake disc, which drives the wheel rim 8 to slow down. The wheel rim 8 is fixed to the ring gear 11, which in turn acts on the planetary gears 18, ultimately stopping the entire reducer system and achieving the braking effect. For the lubrication system of the reducer system, when it is not working, lubricating oil is injected through the breather valve 1, and the amount of oil only needs to reach the first planetary gear. When the gears are working, the lubricating oil will reach all tooth surfaces through gear meshing. The front O-ring and the rear oil seal 9 ensure that the lubricating oil will not leak. When the working temperature rises, the pressure in the cavity increases. The breather valve 1 adjusts the internal and external air pressure by exhausting air, making the working system stable.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A four-wheel independent wheel-side reduction drive system suitable for a formula car, wherein the planetary gear system comprises a front planet carrier, a rear planet carrier, a planet shaft, a planetary gear, a sun gear and a ring gear; One end of the planet shaft is connected to the front planet carrier, and the other end is connected to the rear planet carrier. There are three planet shafts, and the three planet shafts are arranged in a ring array between the front planet carrier and the planet carrier. A planet wheel is installed on each planet shaft. The small-toothed end of the planet wheel meshes with the ring gear, and the large-toothed end meshes with the sun gear. The two ends are matched with the front planet carrier and the rear planet carrier respectively. The sun gear is stepped, with a smaller shaft diameter on the tooth side, and is used to assemble the sun gear bearing. The outer side of the sun gear bearing matches the front planet carrier. The sun gear is provided with an internal spline inside, which is interference fit with the spline of the motor output shaft, and the sun gear is connected to the motor output shaft through a sun gear connecting bolt; The front planet carrier is connected to the rear planet carrier by planet carrier connecting bolts. The front planet carrier is provided with three triangular prism-shaped bosses in a circle. The upper surface of the bosses is completely in contact with the rear planet carrier, and a center hole for matching the planet carrier connecting bolts is provided at the center of the bosses. A first mounting groove is provided at one end of the boss hole close to the rear planet carrier, a steel sleeve is installed in the first mounting groove, and one end of the steel sleeve is installed in the first mounting groove, and the other end of the steel sleeve is installed in the second mounting groove opened on the rear planet carrier. The rear part of the front planet carrier is also provided with six pin holes distributed in concentric circles, one end of the metal pin is matched with the pin hole, and the other end is matched with the pin hole of the corresponding steering knuckle. A rear oil seal is installed on the inner side of the wheel edge, and the outer side of the wheel edge is connected to the cover plate, and an O-ring installation groove for installing an O-ring is provided on the connection side. The depth of the O-ring installation groove is smaller than the wire diameter of the O-ring, and the remaining part is squeezed and cooperated with the cover plate to form a sealed space. A breathable valve is installed at the axis of the cover plate through a threaded hole.

2. The four-wheel independent wheel-side reduction drive system suitable for a formula car according to claim 1, characterized in that: The rear planetary carrier is installed on the inner side of the rear planetary carrier bearing, and the outer side of the rear planetary carrier bearing is installed in the first bearing mounting groove set in the working space. The front planetary carrier is installed on the inner side of the front planetary carrier bearing, and the outer side of the front planetary carrier bearing is installed in the second bearing mounting groove set in the working space.

3. The four-wheel independent wheel-side reduction drive system suitable for a formula car according to claim 1, characterized in that: A gear ring mounting groove is provided inside the wheel rim for fixing the gear ring. Six bolt holes and six pin holes are provided in the gear ring mounting groove. The bolt holes and the pin holes are arranged concentrically and staggered. The bolt holes and the bolts are fastened to limit the axial movement of the gear ring. The pin holes and the metal pins cooperate to limit the radial movement of the gear ring.

4. The four-wheel independent wheel-side reduction drive system suitable for a formula car according to claim 1, characterized in that: The contact side of the rim connection part with the spoke is a flat structure, which fits the spoke, and the non-contact side is an arc structure; the rim connection part is provided with twelve extended ear pieces, each of which is provided with a connecting hole, the contact side of the connecting hole is a threaded hole for bolt fixing, and the rear side is a square groove for limiting the rotation of the horse head bolt connecting the spoke.

5. The four-wheel independent wheel reduction drive system suitable for a formula car according to claim 4, characterized in that: The connection method between the wheel rim and the cover plate is the same as that between the wheel rim and the spoke. Six extended ear pieces extend outside the wheel rim. Each extended ear piece is distributed in an array with the center of the reducer as the axis. The extended ear pieces are connected to the wheel rim through cover plate connecting bolts.

6. The four-wheel independent wheel reduction drive system suitable for a formula car according to claim 1, characterized in that: The distance between the brake disc connection part and the rim connection part is greater than the thickness of the brake caliper; the brake disc connection part is provided with six extended ear pieces, each of which is provided with a threaded hole and is connected to the brake disc by bolts; and the distance from the brake disc connection part to the wheel edge is less than the distance from the rim connection part to the wheel edge.

7. The four-wheel independent wheel-side reduction drive system suitable for a formula car according to claim 1, characterized in that: The planetary shaft is made of 40Cr, and the shaft portion of the planetary shaft is a hollow structure.

8. The four-wheel independent wheel reduction drive system suitable for a formula car according to claim 1, characterized in that: The rear portion of the front planet carrier is provided with six trapezoidal weight-reducing holes, and the rear planet carrier is also provided with three trapezoidal weight-reducing holes.

9. The four-wheel independent wheel reduction drive system suitable for a formula car according to claim 1, characterized in that: The material of the planetary gear is 20CrMnTi.

10. The four-wheel independent wheel-side reduction drive system suitable for a formula car according to claim 1, characterized in that: The upper end of the front planet carrier is provided with three trapezoidal grooves, the small-diameter part of the trapezoidal groove is used to fix the planetary shaft, and the large-diameter part of the trapezoidal groove has a depth of 2 mm and is used to place the first gear gasket and the second gear gasket.

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