A coaxial electric drive axle with large reduction ratio and vehicle

Abstract

The utility model discloses a coaxial electric drive axle of big reduction ratio and vehicle, including motor, reduction mechanism and differential, reduction mechanism at least includes sun gear, planetary gear assembly, support ring gear and output ring gear, and differential includes rotator and two drive shafts, and planetary gear assembly includes planet carrier and with coaxial connection's first planetary gear and second planetary gear, and the rotor axle of motor is connected sun gear, and sun gear connects first planetary gear and / or second planetary gear, and first planetary gear and support ring gear are engaged, and second planetary gear and output ring gear are engaged, and output ring gear connects rotator, and one drive shaft of differential is arranged in the axle of rotor axle and sun gear's axle center, to guarantee the torque of motor output deceleration, increase the twist after transmission to rotator through reduction mechanism, and then guarantee the torque distribution to two drive shafts, and such can realize big reduction ratio, and the whole radial dimension is small, and cost is low and occupies small space.

Description

Technical Field

[0001] This utility model relates to the field of motor drive technology, and in particular to a coaxial electric drive axle with a large reduction ratio and a vehicle. Background Technology

[0002] With the development of automotive electric drive system technology, electric drive axle technology is also developing rapidly.

[0003] The electric drive axle is a crucial component of the electric vehicle's transmission system. Its function is to transmit the power output from the electric motor to the wheels, propelling the vehicle. Electric drive axles are classified into two types: integrated and distributed. The following discussion focuses solely on integrated electric drive axles. An integrated electric drive axle typically consists of a drive motor, a reduction gear, a differential, and two half-shafts. The drive motor outputs power; the reduction gear amplifies and reduces the torque output from the motor to meet the vehicle's driving needs; and the differential distributes the torque output from the reduction gear to the left and right wheels, ensuring that both wheels receive driving torque and that the wheels can drive differentially, guaranteeing smooth vehicle movement during cornering.

[0004] High speed is the development trend of drive motors. The output power of a motor is equal to the product of its speed and torque. Increasing the motor speed can increase the power density, thereby reducing the size and weight of the motor and lowering costs. With the technological iteration and development of high-speed motors, the (maximum) speed of drive motors has increased from about 10,000 rpm a few years ago to about 15,000 rpm. Currently, many motors under development have increased their speed to 20,000 rpm, and in the future, the motor speed will most likely increase to 25,000-30,000 rpm.

[0005] The reduction ratio of a reduction gear increases with the motor speed. Currently, many passenger car reduction gears have a speed ratio of approximately 10:1 (hereinafter referred to as a speed ratio of 10); a 20,000 rpm motor requires approximately a speed ratio of 15; and a 25,000–30,000 rpm motor will require a speed ratio of 15–20. Commercial vehicles have lower speeds and larger wheels, requiring even higher speed ratios, potentially reaching 30–50.

[0006] Patent CN212737630U, authorized by patent authority, proposes an integrated three-stage reduction electric drive axle. This patent includes an integrated housing containing a motor, a three-stage parallel reduction gear set, and a differential, all sequentially connected. The three-stage parallel reduction gear set, differential, and integrated housing are a single, integrally formed structure. To achieve a high speed ratio reduction, this patent uses a three-stage parallel reduction gear set. Although it employs a similar double-tooth structure for a relatively reasonable arrangement of the gears, the overall drive axle uses a three-stage parallel shaft structure, inevitably resulting in an excessively large overall size, which is detrimental to the overall machine layout. In summary, the parallel shaft electric drive axle is a combination of a motor, reduction mechanism, and differential; its lateral dimension is approximately 200mm larger than that of the motor and reducer, compressing the space available for battery placement.

[0007] Patent CN222223885U, authorized by the patent, proposes an electric drive axle design with the motor perpendicular to the axle. The reduction mechanism of this patent adopts a quasi-hypoid gear structure, including a quasi-hypoid gear, a driving gear, and a driven gear. The axes of the driving gear and the driven gear intersect at a 90° angle. Its biggest feature is that it can change the direction of power transmission by 90°, while achieving speed reduction and torque increase. The motor and the half-shaft of the vehicle are also arranged at a 90° angle, which can appropriately reduce the axial dimension of the electric drive axle. However, the lateral dimension of the drive axle is the sum of the axial length of the motor and the reduction mechanism and the outer diameter of the differential. It is relatively large and has a T-shaped shape, occupying a large space and encroaching on the space for battery pack placement.

[0008] Patent application CN118560262A proposes a coaxial electric drive axle design. This patent employs an NGW-type planetary gear reduction mechanism, including a sun gear, planet gears, an internal gear ring, and a planet carrier. This reduction mechanism boasts advantages such as compact structure, high load-bearing capacity, and high transmission efficiency. In particular, the coaxial design of the motor, reducer, and differential significantly reduces the lateral dimensions, freeing up valuable chassis space for battery placement. The first embodiment of this patent uses an NGW-type planetary gear set as the reduction mechanism, and a double planetary gear set and clutch constitute the transmission mechanism. However, the speed ratio is relatively small and cannot meet the high-speed ratio requirements of high-speed motors. The second embodiment of this patent, in order to increase the reducer speed ratio, adds another single-stage NGW-type planetary gear in series with the existing single-stage NGW-type planetary gear reducer. The system consists of a two-stage NGW-type planetary gear reducer and a double planetary gear set transmission mechanism, which can meet current speed ratio requirements. However, the system includes three planetary gear mechanisms, resulting in more components and increased size, weight, and cost.

[0009] Coaxial electric drive axles require planetary gear sets as the reduction mechanism. In coaxial electric drive axles, the differential's main reduction gear is no longer needed, so the reduction mechanism must have a sufficiently large speed ratio of 10–40. In coaxial drive axles, the differential's half-shaft / drive shaft passes through the interior of the sun gear / shaft, so the sun gear's diameter needs to be sufficiently large. On the other hand, the ring gear diameter cannot be too large; that is, the ratio of the ring gear teeth to the sun gear teeth, p = R / S, should not be too large, generally not exceeding 3.0. The total speed ratio of two-stage planetary gear sets in series is generally not greater than (p+1)(p+1) = 16, which cannot meet future requirements. Furthermore, the number of parts in a two-stage NGW-type planetary gear reducer has doubled compared to before, significantly increasing costs and eliminating any cost advantage. A compound planetary gear set could also be considered as the reduction mechanism for coaxial electric drive axles, but this would encounter the contradiction between increasing the speed ratio and limiting the ring gear diameter. Utility Model Content

[0010] To address the aforementioned problems, this invention provides a coaxial electric drive axle and vehicle with a large reduction ratio, which can achieve a large reduction ratio, and the entire system has a small radial dimension, low cost, and small footprint.

[0011] To achieve the above objectives, the technical solution provided by this utility model is as follows:

[0012] This utility model provides a coaxial electric drive axle with a large reduction ratio, including a motor, a reduction mechanism, and a differential; the reduction mechanism includes at least a sun gear, a planetary gear assembly, a fixedly mounted support gear ring, and an output gear ring for outputting power; the planetary gear assembly includes a planet carrier and a first planetary gear and a second planetary gear coaxially and fixedly connected to the planet carrier, the two planetary gears being rotatable about their own axes, and the two planetary gear shafts being fixedly mounted on the planet carrier; the differential includes a rotatable rotating component and two drive shafts (i.e., half-shafts) for driving two wheels respectively; the rotor shaft of the motor is connected to the sun gear, and the sun gear and... The first planetary gear and / or the second planetary gear mesh, the first planetary gear meshes with the support ring gear, the second planetary gear meshes with the output ring gear, the output ring gear is connected to the rotating component of the differential, one of the drive shafts of the differential is rotatably inserted through the rotor shaft and the axis of the sun gear, so as to ensure that the torque output by the motor is reduced and increased by the reduction mechanism and then transmitted to the rotating component of the differential, thereby ensuring that the corresponding torque is distributed to the two drive shafts, and the rotor shaft, the sun gear, the output ring gear, the rotating component of the differential and the two drive shafts are all arranged on the same axis.

[0013] Furthermore, the rotor shaft and the sun gear of the sun gear unit are respectively configured as hollow shaft structures.

[0014] Furthermore, the sun gear is defined as the first sun gear; the rotor of the motor is connected to the first sun gear through the rotor shaft, and the first sun gear meshes with the first planetary gear.

[0015] Furthermore, the speed ratio η of the coaxial electric drive axle is η = ((P1×R2)×(S1+R1)) / (S1×(P1×R2-P2×R1)).

[0016] Furthermore, the sun gear is defined as the second sun gear; the rotor of the motor is connected to the second sun gear through the rotor shaft, and the second sun gear meshes with the second planetary gear.

[0017] Furthermore, the speed ratio η of the coaxial electric drive axle is η = (R2 × (S2 × P1 + P2 × R1)) / (S2 × (P1 × R2 - P2 × R1)).

[0018] Furthermore, the reduction mechanism also includes a first clutch and a second clutch, and there are two sun gears, which are defined as the first sun gear and the second sun gear respectively; the rotor shaft is connected to the first sun gear through the first clutch; or the rotor shaft is connected to the second sun gear through the second clutch.

[0019] Furthermore, when the first clutch is locked and the second clutch is disengaged, the speed ratio η of the coaxial electric drive axle is η = ((P1×R2)×(S1+R1)) / (S1×(P1×R2-P2×R1)); when the first clutch is disengaged and the second clutch is locked, the speed ratio η of the coaxial electric drive axle is η = (R2×(S2×P1+P2×R1)) / (S2×(P1×R2-P2×R1)).

[0020] Furthermore, the reduction mechanism also includes an output shaft; the rotating component is the input end housing of the differential, and the output ring gear and the input end housing are connected through the output shaft; or the differential also includes a third sun gear, a third planet gear, a fourth planet gear, a second planet carrier, and a rotating ring gear; the output ring gear and the rotating ring gear are connected through the output shaft, and the third sun gear and the second planet carrier are respectively connected to two drive shafts; the rotating ring gear is the rotating component; the torques on the third sun gear, the second planet carrier, and the rotating ring gear have the following relationship: TS=(1-ρ)×TQ and TC=ρ×TQ.

[0021] This utility model provides a vehicle that includes at least the aforementioned coaxial electric drive axle with a large reduction ratio.

[0022] Wherein, η is the ratio between the rotational speed of the motor and the rotational speed of the rotating component, S1 is the number of teeth of the first sun gear, S2 is the number of teeth of the second sun gear, P1 is the number of teeth of the first planetary gear, P2 is the number of teeth of the second planetary gear, R1 is the number of teeth of the supporting gear ring, R2 is the number of teeth of the output gear ring, ρ is the ratio between the number of teeth of the third sun gear and the number of teeth of the rotating gear ring, TS is the torque of the third sun gear, TQ is the torque of the rotating gear ring, and TC is the torque of the second planetary carrier.

[0023] The technical solution provided by this utility model has the following beneficial effects:

[0024] 1. This utility model is driven by a motor, and the torque output by the motor is reduced and increased by the reduction mechanism, and then the motor torque is transmitted to the differential. The differential then distributes the torque to the two drive shafts to drive the left and right wheels respectively. This utility model has the advantages of high power density, small radial size, low cost and small space occupation.

[0025] 2. The lateral dimension of this utility model is equal to the lateral dimension of the motor, reducer, or differential. Compared with parallel-axis electric drive axles and vertical-axis electric drive axles, the lateral dimension and space occupied by this utility model are significantly reduced, saving valuable chassis space for arranging batteries or other systems.

[0026] 3. This utility model can achieve a large reduction ratio through the reduction mechanism, and the range of the reduction ratio is large, such as 10 to 40, or even larger. Therefore, this utility model is particularly suitable for high-speed drive motors.

[0027] 4. The rotor shaft of the motor and the sun gear are both hollow shaft structures. Therefore, the drive shaft of the differential can pass through its shaft hole, thereby making the motor, the reduction mechanism and the differential coaxial.

[0028] 5. This utility model adopts a two-stage compound planetary gear structure, where the ratio of the number of teeth of the maximum ring gear to the minimum sun gear is p = R / S ≤ 3.0. Therefore, the drive shaft of the differential has a large torque and can pass through the shaft hole of the sun gear, while also achieving a large speed ratio and limiting the outer diameter of the ring gear. Other types of two-stage planetary gear mechanisms (serial type and compound type) find it difficult to achieve the same speed ratio.

[0029] 6. This utility model can increase the two gears / speed ratios and integrate the shifting mechanism and the reduction mechanism together, which can realize gear shifting and speed change, and has a reasonable step difference, which can further improve the performance of the electric drive axle. It not only has high torque at low speed, but also good high-speed performance, making it particularly suitable for high-end electric drive axles.

[0030] 7. This utility model adopts a differential without an input gear, and because the reduction ratio of the reduction mechanism is large, the main reduction ratio is not required. Therefore, the main reduction gear and input shaft of the traditional differential can be eliminated, and the differential of this utility model can be directly connected to the output shaft of the reduction mechanism. Attached Figure Description

[0031] Figure 1 The diagram shown is a connection schematic of the coaxial electric drive bridge with a large reduction ratio in Embodiment 1.

[0032] Figure 2 The diagram shown is a connection schematic of the coaxial electric drive bridge with a large reduction ratio in Embodiment 2.

[0033] Figure 3 The diagram shown is a connection schematic of the coaxial electric drive bridge with a large reduction ratio in Embodiment 3.

[0034] Figure 4A The diagram shown is a connection schematic of the coaxial electric drive bridge with a large reduction ratio in Embodiment 4.1.

[0035] Figure 4B The diagram shown is a lever representation of the dual planetary gear differential in Embodiment 4;

[0036] Figure 4C The diagram shown is a lever representation of another configuration of the dual planetary gear differential in Embodiment 4. Detailed Implementation

[0037] To further illustrate the various embodiments, the present invention provides accompanying drawings. These drawings are part of the disclosure of the present invention and are mainly used to illustrate the embodiments, and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementations and the advantages of the present invention. The components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0038] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0039] Example 1

[0040] Reference Figure 1 Example 1 provides a coaxial electric drive axle with a large reduction ratio (hereinafter referred to as electric drive axle) for use in the wheels of an electric drive vehicle, while taking into account both power performance and energy consumption performance.

[0041] The electric drive axle of this embodiment includes an electric drive axle housing 1, a motor 100, a reduction mechanism 200 and a differential 300 (i.e. a bevel gear differential). The reduction mechanism 200 includes a first sun gear 5, a planetary gear assembly 500, an output shaft 12, a fixedly mounted support gear ring 7 and an output gear ring 11 for outputting power.

[0042] The differential 300 includes a rotatable input housing 13 and a first drive shaft 14 and a second drive shaft 15 for driving two wheels respectively. The output gear ring 11 and the input housing 13 of the differential 300 are connected via an output shaft 12. Therefore, the input housing 13 (i.e., one of the rotating parts of the differential 300) is the input end of the differential 300, and the first drive shaft 14 and the second drive shaft 15 are the two output ends of the differential 300. For non-coaxial drive axles, the output shaft of the reduction / transmission mechanism is connected to the differential via a pair of gears, which are called the main reduction gears; the main reduction driven gears are coaxially and fixedly connected to the differential housing. This invention is a coaxial drive axle, in which the output shaft of the reduction mechanism 200 is coaxially arranged with the input housing 13 of the differential 300 and can be directly fixedly connected, eliminating the need for main reduction gears.

[0043] The planetary gear assembly 500 includes a planet carrier 8, a first planetary gear 6, and a second planetary gear 10. The first planetary gear 6 and the second planetary gear 10 are coaxially and fixedly connected. The first planetary gear 6 and the second planetary gear 10 rotate around their own axes, and the two planetary gear shafts are fixedly mounted on the planet carrier 8. The rotor shaft 4 of the motor 100 is connected to the first sun gear 5. The first sun gear 5 meshes with the first planetary gear 6. The first planetary gear 6 meshes with the support ring gear 7. The second planetary gear 10 meshes with the output ring gear 11. The output ring gear 11 is connected to the input end housing 13 of the differential 300 through the output shaft 12. The first drive shaft 14 is rotatably inserted through the axis of the rotor shaft 4 and the first sun gear 5 to ensure that the torque output by the motor 100 is reduced and increased by the reduction mechanism 200 and then transmitted to the input end housing 13 of the differential 300, thereby ensuring that the corresponding torque is distributed to the two drive shafts.

[0044] In this embodiment, the electric drive axle housing 1 is non-rotating, but can move parallel within the constraints of the vehicle's suspension structure. Of course, all components installed on or fixedly connected to the electric drive axle housing 1 are non-rotating and are fixedly installed unless there is any ambiguity.

[0045] The stator 2 of the motor 100 and the housing of the motor 100 are respectively fixedly connected to the electric drive bridge housing 1 and are respectively set to be non-rotatable, and the rotor 3 of the motor 100 outputs torque through the rotor shaft 4.

[0046] More specifically, the rotor 3 of the motor 100 is connected to the first sun gear 5 through the rotor shaft 4. The first sun gear 5 meshes with the first planetary gear 6, and the first planetary gear 6 meshes with the support gear ring 7 at the same time.

[0047] The first planetary gear 6 and the second planetary gear 10 are coaxially and fixedly connected. The second planetary gear 10 meshes with the output gear ring 11. The output gear ring 11 is connected to the input end housing 13 through the output shaft 12.

[0048] Both the rotor shaft 4 and the first sun gear 5 are hollow shaft structures. The first drive shaft 14 passes through the shaft holes of the rotor shaft 4 and the first sun gear 5, and bearings are provided between the first drive shaft 14 and the shafts of the rotor shaft 4 and the first sun gear 5 to achieve mutual support and relative rotation.

[0049] Since the support gear ring 7 is fixedly connected to the electric drive axle housing 1, the rotational speed of the support gear ring 7 is zero.

[0050] During operation, the rotor 3 of the motor 100 outputs torque and drives the first sun gear 5 to rotate through the rotor shaft 4. Power is transmitted to the first planetary gear 6 through the meshing point formed by the meshing of the first sun gear 5 and the first planetary gear 6. Since the rotational speed of the supporting gear ring 7 is zero and the first planetary gear 6 meshes with the supporting gear ring 7, the speed of the meshing point between the first planetary gear 6 and the supporting gear ring 7 is zero.

[0051] The second planetary gear 10 is coaxially and fixedly connected to the first planetary gear 6 and moves with it. The second planetary gear 10 meshes with the output ring gear 11, driving the output ring gear 11 to rotate. The output ring gear 11 is connected to the input end housing 13 through the output shaft 12 to drive the input end housing 13 to rotate. Then, the differential 300 distributes the input torque to the first drive shaft 14 and the second drive shaft 15 to drive the left and right wheels of the vehicle to rotate respectively. The torques of the first drive shaft 14 and the second drive shaft 15 are approximately equal, but they can rotate at different speeds, driving the two wheels to rotate at different speeds to facilitate vehicle turning.

[0052] Furthermore, in this embodiment, the reduction ratio η of the electric drive axle is η = ((P1×R2)×(S1+R1)) / (S1×(P1×R2-P2×R1)). The reduction ratio, also known as the speed ratio, is the ratio of the motor speed to the output shaft speed of the differential.

[0053] As can be seen from the above conditional expression, the denominator contains a difference term (P1×R2-P2×R1). By designing appropriate parameters, the denominator can be made to have a smaller value, thereby enabling the electric drive axle to have a larger reduction ratio.

[0054] From the perspective of gear design, the closer the number of teeth P1 of the first planetary gear 6 is to the number of teeth P2 of the second planetary gear 10, the closer the number of teeth R1 of the supporting gear ring 7 is to the number of teeth R2 of the output gear ring 11. Consequently, the smaller the value of the difference term (P1×R2-P2×R1), the greater the reduction ratio of the electric drive axle.

[0055] Wherein, η is the ratio or speed ratio between the rotational speed of motor 100 and the rotational speed of input housing 13, which is also the reduction ratio of electric drive axle, S1 is the number of teeth of first sun gear 5, P1 is the number of teeth of first planetary gear 6, P2 is the number of teeth of second planetary gear 10, R1 is the number of teeth of support gear ring 7, and R2 is the number of teeth of output gear ring 11.

[0056] When the pitch circle diameter of the first sun gear 5 is set in a small range, and different electric drive axles are designed according to the design parameters in Table 1, and the number of teeth of the first sun gear 5 and the supporting gear ring 7 remains unchanged, the reduction ratios η of the corresponding electric drive axles are 9.5, 11.8, 14.9, 19.9, 28.7 and 35.7 as shown in Table 1.

[0057] Table 1:

[0058] S1 P1 P2 R1 R2 η 21 30 12 81 66 9.5 21 30 15 81 69 11.8 21 30 18 81 72 14.9 21 30 21 81 75 19.9 21 30 24 81 78 28.7 21 30 24 81 75 35.7

[0059] Furthermore, p in the planetary gear structure is defined as the ratio between the number of teeth of the supporting ring gear 7 and the first sun gear 5. When the p value of the planetary gear structure of the electric drive axle designed as shown in Table 1 is 3.85, a problem arises: if the pitch circle diameter of the first sun gear 5 is large, the diameter of the supporting ring gear 7 and the diameter of the reducer will also be large, which is prone to problems in ring gear manufacturing, NVH, etc. Also, since the diameter of the supporting ring gear 7 determines the outer diameter of the reduction mechanism 200, and a large diameter ring gear will bring many problems, the diameter of the supporting ring gear 7 cannot be too large; if the diameter of the supporting ring gear 7 is small, the pitch circle diameter of the first sun gear 5 will inevitably be small, therefore, the inner diameter of the shaft of the first sun gear 5 will inevitably be small, which will lead to assembly difficulties when arranging the drive shaft and bearings in the shaft hole of the first sun gear 5.

[0060] To avoid the above problems, the planetary gear structure with a smaller p-value needs to be redesigned, as shown in Table 2 below:

[0061] Table 2:

[0062] S1 P1 P2 R1 R2 η 42 30 18 102 90 10.7 42 30 21 102 93 14.8 42 30 24 102 99 19.5 42 30 24 102 93 28.0 42 30 27 102 102 34.3

[0063] Based on Table 2, each electric drive axle was designed with a p-value of 2.43 (i.e., R1 / S1) for its planetary gear structure. The reduction ratios η of each electric drive axle are 10.7, 14.8, 19.5, 28.0 and 34.3, as shown in Table 2. At this point, the p-value is more reasonable. The pitch circle diameter of the first sun gear 5 is relatively large, which makes it convenient to arrange the drive shaft and bearing in the shaft hole of the first sun gear 5. At the same time, the outer diameter of the supporting gear ring 7 is not very large, which can reduce a lot of trouble.

[0064] In addition, compared to the traditional simple planetary gear structure with p≤3, its reduction ratio is ≤4, the total speed ratio of the two-stage series gear is ≤16, and the speed ratio of the sun gear to the ring gear is p+1 and not greater than 4. Therefore, the traditional simple planetary gear structure cannot meet the requirement of a reduction ratio of 10 to 40, that is, it is difficult to achieve a larger reduction ratio.

[0065] In summary, the electric drive bridge of this embodiment can achieve the following effects and advantages:

[0066] 1. In this embodiment, a motor 100 drives the vehicle, and the torque output by the motor 100 is reduced and increased by the reduction mechanism 200. Then, the motor torque is transmitted to the differential 300, and the differential 300 distributes the torque to the two drive shafts to drive the left and right wheels respectively. This embodiment has the advantages of high power density, small radial size, low cost and small space occupation.

[0067] 2. The rotor shaft 4 and the first sun gear 5 of the motor 100 are hollow shaft structures, so the drive shaft of the differential 300 can pass through its shaft hole, thereby realizing the coaxial arrangement of the motor 100, the reduction mechanism 200 and the differential 300.

[0068] 3. In this embodiment, a large reduction ratio can be achieved through the reduction mechanism 200, and the range of the reduction ratio is large, such as 10 to 40, or even larger. Therefore, the electric drive axle of this embodiment is particularly suitable for high-speed drive motors, and is also applicable to commercial vehicles and engineering vehicles, which have larger wheels, lower vehicle speeds, and require a larger reduction ratio.

[0069] 4. This embodiment uses a differential 300 without an input gear. Since the reduction ratio of the reduction mechanism 200 is large, the main reduction ratio is not required. Therefore, the main reduction gear and input shaft of the traditional differential can be eliminated, and the differential 300 of this embodiment can be directly connected to the output shaft 12 of the reduction mechanism 200.

[0070] 5. This embodiment adopts a two-stage composite planetary gear structure, with the ratio of the number of teeth of the maximum ring gear to the minimum sun gear p≤3.0. Therefore, the drive shaft of the differential 300 has a large torque and can pass through the shaft hole of each sun gear. It can also achieve a large speed ratio and limit the outer diameter of the ring gear.

[0071] 6. Compared to non-coaxial electric drive axles, where the motor, reducer, and differential are arranged side-by-side, resulting in a larger lateral dimension and requiring more installation space, the coaxial electric drive axle of this embodiment places the motor 100, reducer 200, and differential 300 on the same axis, thereby reducing the overall size and space occupied. The outer diameter of the motor is the largest among the three components, which is the lateral dimension of the coaxial electric drive axle. In addition, the coaxial electric drive axle is generally cylindrical in shape, which can achieve a simple shape and good utilization of vehicle body space.

[0072] 7. Compared to the traditional coaxial electric drive axle composed of planetary gear sets, since a single-stage planetary gear set can provide a speed ratio of p+1, its p value should generally not be too large, and the speed ratio is usually no greater than 4. Therefore, a reducer composed of two-stage planetary gear sets is required, and the speed ratio is usually no greater than 15. The traditional reducer composed of two-stage planetary gear sets includes two sun gears, two sets of planetary gear assemblies, two ring gears, and four rotating parts. Such components are numerous. However, the electric drive axle in this embodiment only includes one sun gear, one set of planetary gear assemblies, two ring gears, and three rotating parts. The number of components and rotating parts required in this embodiment is also less, the structure is simpler, and the axial dimension is shorter, which is beneficial for layout and installation and has a lower cost.

[0073] Example 2

[0074] like Figure 2 As shown, Embodiment 2 provides a coaxial electric drive bridge with a large reduction ratio. The structure of Embodiment 2 is generally the same as that of Embodiment 1, except that: this embodiment is provided with a second sun gear 9 to replace the first sun gear in Embodiment 1, and the rotor 3 of the motor 100 is connected to the second sun gear 9 through the rotor shaft 4, and the second sun gear 9 meshes with the second planetary gear 10.

[0075] The reduction ratio of the electric drive axle in this embodiment is η=(R2×(S2×P1+P2×R1)) / (S2×(P1×R2-P2×R1)).

[0076] Wherein, η is the ratio between the rotational speed of motor 100 and the rotational speed of input housing 13, which is also the reduction ratio of electric drive axle, S2 is the number of teeth of second sun gear 9, P1 is the number of teeth of first planetary gear 6, P2 is the number of teeth of second planetary gear 10, R1 is the number of teeth of support gear ring 7, and R2 is the number of teeth of output gear ring 11.

[0077] Table 3:

[0078] S2 P1 P2 R1 R2 η 42 36 21 99 87 7.1 39 36 24 99 90 10.1 36 36 27 99 93 15.2 36 36 27 99 87 20.9 33 39 30 99 93 31.0 33 36 30 99 90 42.0

[0079] Based on Table 3, the p-values ​​of the planetary gear structures of each electric drive axle are designed to be between 2.36 and 3.00. The reduction ratios of each electric drive axle are 7.1, 10.1, 15.2, 31.0, and 42.0, respectively. These p-values ​​are also relatively reasonable. The pitch circle diameter of the first sun gear 5 is also relatively large, which facilitates the arrangement of the drive shaft and bearings within the shaft hole of the first sun gear 5. Simultaneously, the outer diameter of the supporting gear ring 7 is not very large, reducing many complications. Of course, in this embodiment, p represents the ratio between the number of teeth of the second sun gear 9 and the number of teeth of the supporting gear ring 7 (i.e., R1 / S2).

[0080] In summary, this embodiment has advantages such as high power density, small radial dimension, low cost and small space occupation, and also takes into account a large reduction ratio.

[0081] Example 3

[0082] like Figure 3 As shown, Embodiment 3 provides a coaxial electric drive axle with two gears and dual speed ratios. The reduction mechanism of Embodiment 3 is a superposition of the reduction mechanisms of Embodiments 1 and 2, and has two sun gears, namely the first sun gear 5 and the second sun gear 9, as the input shaft. The reduction mechanism 200' also includes a first clutch 31 and a second clutch 32 as a shifting mechanism, which selects the first sun gear 5 or the second sun gear 9 as the input gear to obtain different speed ratios, thereby realizing speed change.

[0083] When the first clutch 31 is closed and the second clutch 32 is disengaged, the rotor shaft 4 of the motor 100 is connected to the first sun gear 5. The first sun gear 5, the first planetary gear 6, the support gear ring 7, the second planetary gear 10 and the output gear ring 11 constitute the first transmission channel. The number of teeth of the above gears and gear rings determines the speed ratio of the first transmission channel. At this time, the motor 100 outputs power through the first transmission channel.

[0084] When the first clutch 31 is disengaged and the second clutch 32 is engaged, the rotor shaft 4 of the motor 100 is connected to the second sun gear 9. The second sun gear 9, the second planetary gear 10, the first planetary gear 6, the support gear ring 7, and the output gear ring 11 constitute the second transmission channel. The number of teeth of the aforementioned gears and gear rings determines the speed ratio of the second transmission channel, and the motor 100 outputs power through the second transmission channel.

[0085] By switching the opening and closing states of the first clutch 31 and the second clutch 32, the corresponding power transmission channels can be switched, thereby setting the electric drive axle of this embodiment as a two-speed coaxial electric drive axle with dual speed ratios to meet the requirements of different output torques.

[0086] When the first clutch 31 is locked and the second clutch 32 is disengaged, the speed ratio η1 of the coaxial electric drive axle is ((P1×R2)×(S1+R1)) / (S1×(P1×R2-P2×R1)).

[0087] When the first clutch 31 is disengaged and the second clutch 32 is locked, the speed ratio η2 of the coaxial electric drive axle is (R2×(S2×P1+P2×R1)) / (S2×(P1×R2-P2×R1)).

[0088] In this embodiment, the shafts of the first drive shaft 14, the second sun gear 9, and the first sun gear 5 are arranged in a shaft-within-a-shaft, and then shaft-within-a-shaft arrangement. At this time, the diameter of the first sun gear 5 needs to be increased, and the p value of the planetary gear structure also needs to be further limited.

[0089] Based on Table 4, the p values ​​of each electric drive axle are designed to be 2.867 (R1 / S1) and 2.105 (R1 / S2) for their planetary gear structures. The reduction ratios of each electric drive axle are 16.7 or 11.3, 18.2 or 12.3, and 20.2 or 13.6, respectively. At this point, the p value is relatively reasonable, and it has two speed ratios η1 and η2, with a range η1 / η2 of 1.48. This can effectively increase the adjustable range of the reduction ratio.

[0090] Table 4:

[0091] S1 S2 P1 P2 R1 R2 η1 η2 45 57 42 30 129 120 16.7 11.3 45 57 42 30 129 117 18.2 12.3 45 57 42 30 129 114 20.2 13.6

[0092] Therefore, the electric drive axle in this embodiment has two gears and two speed ratios, which can further improve the performance of the electric drive axle. The electric drive axle not only has high torque at low speeds, but also good high-speed performance, making it especially suitable for high-speed electric drive axles.

[0093] Example 4

[0094] like Figure 4A , Figure 4B and Figure 4C As shown, Embodiment 4 provides a coaxial electric drive axle with a large reduction ratio. The structure of Embodiment 4 is generally the same as that of Embodiment 1, except that the differential 300' in this embodiment includes a third sun gear 20, a third planetary gear 21, a fourth planetary gear 22, a second planetary carrier 23, and a rotating ring gear 24. In this case, the rotating ring gear 24 is a rotating component, replacing the input end housing of Embodiment 1. Therefore, the differential 300' in this embodiment is a planetary gear differential or a double planetary gear differential. Although it is different from the differential of Embodiment 1, the axial dimension of the differential 300' can be further reduced.

[0095] In this embodiment, the differential 300' adopts a double planetary gear structure. The output ring gear 11 and the rotating ring gear 24 are connected through the output shaft 12. The third sun gear 20 and the second planetary carrier 23 are respectively connected to the first drive shaft 14 and the second drive shaft 15.

[0096] In this embodiment, the torques on the third sun gear 20, the second planetary carrier 23, and the rotating ring gear 24 of the electric drive axle have the following relationship: TS=(1-ρ)×TQ and TC=ρ×TQ.

[0097] Wherein, ρ is the ratio between the number of teeth of the third sun gear 20 and the number of teeth of the rotating ring gear 24, TS is the torque of the third sun gear 20, TQ is the torque of the rotating ring gear 24, and TC is the torque of the second planetary carrier 23.

[0098] If the value of ρ is set to approximately 0.50, the input torque can be evenly distributed to the two drive shafts.

[0099] Also, such as Figure 4B The diagram shown is a lever representation of a dual planetary gear differential, where R is the ring gear, S is the sun gear, and C is the planet carrier. If the torque of R is TQ, then the torque of S is TS=(1-ρ)×TQ, and the torque of C is TC=ρ×TQ.

[0100] Figure 4C The diagram shows another type of lever representation of a dual planetary differential, and defines the constraint relationships between the rotational speeds of the S, R, and C axes.

[0101] Example 5

[0102] Example 5 provides a vehicle that includes at least one coaxial electric drive axle with a large reduction ratio, as described in Example 1, Example 2, Example 3, or Example 4.

[0103] Although the present invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the present invention without departing from the spirit and scope of the present invention as defined in the appended claims, and all such changes shall be within the scope of protection of the present invention.

Claims

1. A coaxial electric drive axle with a large reduction ratio, characterized in that: Includes the motor, reduction gear, and differential; The reduction mechanism includes at least a sun gear, a planetary gear assembly, a fixedly mounted support gear ring, and an output gear ring for outputting power. The planetary gear assembly includes a planet carrier and a first planetary gear and a second planetary gear coaxially fixedly connected to the planet carrier. The two planetary gears can rotate around their own axes, and the shafts of the two planetary gears are fixedly mounted on the planet carrier. The differential includes a rotatable rotating component and two drive shafts for driving the two wheels respectively. The rotor shaft of the motor is connected to the sun gear, which meshes with the first planetary gear and / or the second planetary gear. The first planetary gear meshes with the support ring gear, and the second planetary gear meshes with the output ring gear. The output ring gear is connected to the rotating component of the differential. One of the drive shafts of the differential is rotatably inserted through the rotor shaft and the axis of the sun gear to ensure that the torque output by the motor is reduced and amplified by the reduction mechanism before being transmitted to the rotating component of the differential, thereby ensuring that the corresponding torque is distributed to the two drive shafts. The rotor shaft, the sun gear, the output ring gear, the rotating component of the differential, and the two drive shafts are all arranged on the same axis.

2. The coaxial electric drive axle with a large reduction ratio according to claim 1, characterized in that: The rotor shaft and the sun gear are both configured as hollow shafts.

3. The coaxial electric drive axle with a large reduction ratio according to claim 1, characterized in that: The sun gear is defined as the first sun gear; the rotor of the motor is connected to the first sun gear through the rotor shaft, and the first sun gear meshes with the first planetary gear.

4. The coaxial electric drive axle with a large reduction ratio according to claim 3, characterized in that: The speed ratio η of the coaxial electric drive axle is η = ((P1×R2)×(S1+R1)) / (S1×(P1×R2-P2×R1)), where η is the ratio or speed ratio between the rotational speed of the motor and the rotational speed of the rotating component, S1 is the number of teeth of the first sun gear, P1 is the number of teeth of the first planetary gear, P2 is the number of teeth of the second planetary gear, R1 is the number of teeth of the support gear ring, and R2 is the number of teeth of the output gear ring.

5. The coaxial electric drive axle with a large reduction ratio according to claim 1, characterized in that: The sun gear is defined as the second sun gear; the rotor of the motor is connected to the second sun gear through the rotor shaft, and the second sun gear meshes with the second planetary gear.

6. The coaxial electric drive axle with a large reduction ratio according to claim 5, characterized in that: The speed ratio η of the coaxial electric drive axle is η = (R2 × (S2 × P1 + P2 × R1)) / (S2 × (P1 × R2 - P2 × R1)), where η is the ratio or speed ratio between the rotational speed of the motor and the rotational speed of the rotating component, S2 is the number of teeth of the second sun gear, P1 is the number of teeth of the first planetary gear, P2 is the number of teeth of the second planetary gear, R1 is the number of teeth of the support gear ring, and R2 is the number of teeth of the output gear ring.

7. The coaxial electric drive axle with a large reduction ratio according to claim 1, characterized in that: The reduction mechanism further includes a first clutch and a second clutch, and there are two sun gears, which are defined as the first sun gear and the second sun gear respectively; the rotor shaft is connected to the first sun gear through the first clutch; or the rotor shaft is connected to the second sun gear through the second clutch.

8. The coaxial electric drive axle with a large reduction ratio according to claim 7, characterized in that: When the first clutch is locked and the second clutch is disengaged, the speed ratio η of the coaxial electric drive axle is ((P1×R2)×(S1+R1)) / (S1×(P1×R2-P2×R1)); When the first clutch is disengaged and the second clutch is locked, the speed ratio η of the coaxial electric drive axle is (R2×(S2×P1+P2×R1)) / (S2×(P1×R2-P2×R1)); Where η is the ratio or speed ratio between the rotational speed of the motor and the rotational speed of the rotating component, S1 is the number of teeth of the first sun gear, S2 is the number of teeth of the second sun gear, P1 is the number of teeth of the first planetary gear, P2 is the number of teeth of the second planetary gear, R1 is the number of teeth of the support gear ring, and R2 is the number of teeth of the output gear ring.

9. The coaxial electric drive axle with a large reduction ratio according to any one of claims 1-8, characterized in that: The reduction mechanism further includes an output shaft; the rotating component is the input end housing of the differential, and the output ring gear and the input end housing are connected through the output shaft; or the differential further includes a third sun gear, a third planet gear, a fourth planet gear, a second planet carrier, and a rotating ring gear; the output ring gear and the rotating ring gear are connected through the output shaft, and the third sun gear and the second planet carrier are respectively connected to two drive shafts; the rotating ring gear is the rotating component; the torques on the third sun gear, the second planet carrier, and the rotating ring gear have the following relationship: TS=(1-ρ)×TQ and TC=ρ×TQ, where ρ is the ratio between the number of teeth of the third sun gear and the number of teeth of the rotating ring gear, TS is the torque of the third sun gear, TQ is the torque of the rotating ring gear, and TC is the torque of the second planet carrier.

10. A vehicle, characterized in that: It includes at least the coaxial electric drive axle with a large reduction ratio as described in any one of claims 1-9.

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