Electric drive axle for heavy truck

Abstract

This invention provides an electric drive axle for a heavy-duty truck, comprising: an axle body and first and second motors and a planetary transmission mechanism mounted thereon and coaxially arranged thereon; the planetary transmission mechanism has three gears, including a transmission mechanism and a reduction differential mechanism connected to each other; the transmission mechanism has three input shafts and an output component, including two planetary gear sets and two shifting elements, the third input shaft is fixedly connected to the output component and the input component of the reduction differential mechanism, the two shifting elements are configured to simultaneously connect the rotor brackets of the first and second motors to one input shaft to achieve dual-motor drive at the same gear, and can also simultaneously connect the rotor brackets of the first and second motors to two input shafts respectively to achieve dual-motor drive at different gears; the reduction differential mechanism achieves a reduction ratio equal to a 3-speed ratio, including a third and fourth planetary gear set connected to each other, one component of the third planetary gear set is connected to the left wheel through the left half-shaft, and one component of the fourth planetary gear set is connected to the left wheel through the right half-shaft.

Description

Technical Field

[0001] This invention relates to the field of vehicle drive transmission technology, specifically to an electric drive axle for heavy-duty trucks, and more particularly to a coaxial electric drive axle that uses planetary gear transmission throughout. Background Technology

[0002] CN114514388A discloses a 13-ton electric drive axle for heavy-duty trucks, which coaxially houses two identical drive motors, a three-speed transmission mechanism consisting of two planetary gear sets and two shifting elements, a bevel gear differential, and two wheel-side reducers. The three gear ratios are 22.2 / 15.4 / 9.2. One motor is the main motor, and the other is the auxiliary motor. The three-speed transmission mechanism, embedded in the rotor cavities of the two motors, outputs the power from the main motor by means of a first shifting element. The second shifting element connects the auxiliary motor rotor bracket to the main motor rotor bracket, allowing the auxiliary motor to also participate in driving the vehicle using the three gears. It can also connect the auxiliary motor rotor bracket to the sun gear of the second planetary gear set, coordinating with the main motor to provide power compensation.

[0003] However, this electric drive axle still has the following aspects that need improvement: the differential is essentially a planetary gear set, so the transmission mechanism uses a total of five planetary gear sets, making the structure relatively complex; when the auxiliary motor fails and disengages from the planetary gear set, the main motor can drive the vehicle independently using three gears, but when the main motor fails and disengages, the auxiliary motor cannot drive the vehicle, resulting in low system fault tolerance; when the vehicle is unloaded or half-loaded, in order to improve driving efficiency, one motor is usually stationary while the other motor drives the vehicle independently, i.e., it has a single-motor working mode. As mentioned earlier, the main motor can utilize three gears... The main motor drives the vehicle independently, while the auxiliary motor cannot. Therefore, it's impossible for the two motors to alternately drive the vehicle independently. The main motor reaches the end of its lifespan prematurely due to frequent use, while the auxiliary motor has a longer lifespan, which is detrimental to ensuring the electric drive axle's B10 lifespan of millions of kilometers. The first gear ratio is too low; a conventional geometric progression configuration should achieve around 30. This is due to the connection relationship between the two planetary gear sets and their placement within the main motor rotor cavity. This requires a low structural characteristic parameter k for both planetary gear sets, with calculated values ​​around 2.2. Therefore, a more comprehensive electric drive axle with superior overall performance is needed to meet the demands of the heavy-duty truck market. Summary of the Invention

[0004] In view of the above-mentioned problems existing in the prior art, an electric drive axle for heavy-duty trucks is provided.

[0005] The specific technical solution is as follows: An electric drive axle for a heavy-duty truck includes: an axle body; a first motor, a second motor, and a planetary transmission mechanism mounted on the axle body and coaxially arranged; the planetary transmission mechanism has 1st gear, 2nd gear, and 3rd gear, and includes a transmission mechanism and a reduction differential mechanism connected to it; the transmission mechanism has a first input shaft, a second input shaft, a third input shaft, and an output component, and includes a first planetary gear set, a second planetary gear set, a first shift element, and a second shift element; the third input shaft is fixedly connected to the output component and the input component of the reduction differential mechanism; the first shift element and the second shift element are configured to connect the first motor rotor bracket and the second motor rotor bracket to the... Simultaneous connection of one of the first, second, and third input shafts enables dual-motor drive at the same gear. Alternatively, the first and second motor rotor brackets can be simultaneously connected to two of the first, second, and third input shafts to enable dual-motor drive at different gears. The reduction differential mechanism achieves a reduction ratio equal to a 3-speed ratio and includes a connected third and fourth planetary gear set. One component of the third planetary gear set serves as the left output component of the reduction differential mechanism and is connected to the left wheel via the left half-shaft. One component of the fourth planetary gear set serves as the right output component of the reduction differential mechanism and is connected to the left wheel via the right half-shaft.

[0006] Preferably, the first input shaft, the second input shaft, and the third input shaft are coaxially arranged sequentially; the first shifting element is a sliding sleeve inserted on the first motor rotor bracket, and when it moves axially in one direction to sequentially connect the first motor rotor bracket with the three input shafts of the transmission mechanism, it realizes gear 1, gear 2, and gear 3; the second shifting element is a sliding sleeve inserted on the second motor rotor bracket, and when it moves axially in one direction to sequentially connect the second motor rotor bracket with the three input shafts of the transmission mechanism, it realizes gear 1, gear 2, and gear 3.

[0007] Preferably, the axial lengths of the first input shaft shift tooth, the second input shaft shift tooth, and the third input shaft shift tooth are all set to be greater than the sum of the axial lengths of the first shift element shift tooth and the second shift element shift tooth. The axial clearances between the first and second input shaft shift teeth and between the second and third input shaft shift teeth are all set to be greater than the axial lengths of either the first or second shift element shift tooth. The axial clearance on the outer side of the end of the first input shaft shift tooth away from the second input shaft shift tooth is set to be greater than the sum of the axial lengths of the first and second shift element shift teeth. The axial clearance on the outer side of the end of the third input shaft shift tooth away from the second input shaft shift tooth is set to be greater than the axial length of either the first or second shift element shift tooth.

[0008] Preferably, the first planetary gear set includes a first sun gear, a first planet carrier, and a first ring gear; the second planetary gear set includes a second sun gear, a second planet carrier, and a second ring gear; both the first ring gear and the second sun gear are fixed, the first sun gear is fixedly connected to the first input shaft, the second ring gear is fixedly connected to the second input shaft, and the first planet carrier and the second planet carrier are fixedly connected as output components of the transmission mechanism.

[0009] Preferably, the first planetary gear set is a single-row, double-star, internally and externally meshing planetary gear set, which includes a first sun gear, a first planet carrier, and a first ring gear; the second planetary gear set includes a second sun gear, a second planet carrier, and a second ring gear; both the first sun gear and the second sun gear are fixed, the first planet carrier is fixedly connected to the first input shaft, the second ring gear is fixedly connected to the second input shaft, and the first ring gear and the second planet carrier are fixedly connected as output components of the transmission mechanism.

[0010] Preferably, the first planetary gear set includes a first sun gear, a first planet carrier, and a first ring gear; the second planetary gear set includes a second sun gear, a second planet carrier, and a second ring gear; both the first and second ring gears are fixed, the first planet carrier is fixedly connected to the second sun gear, the first sun gear is fixedly connected to the first input shaft, the second sun gear is fixedly connected to the second input shaft, and the second planet carrier serves as the output component of the transmission mechanism.

[0011] Preferably, the first planetary gear set is a single-row, double-star, internally and externally meshing planetary gear set, including a first sun gear, a first planet carrier, and a first ring gear; the second planetary gear set is a single-row, double-star, internally and externally meshing planetary gear set, including a second sun gear, a second planet carrier, and a second ring gear; both the first and second planet carriers are fixed, the first ring gear is fixedly connected to the second sun gear, the first sun gear is fixedly connected to the first input shaft, the second sun gear is fixedly connected to the second input shaft, and the second ring gear serves as the output component of the transmission mechanism.

[0012] Preferably, the third planetary gear set includes a third sun gear, a third planet carrier, and a third ring gear; the fourth planetary gear set is a single-row, double-star, internally and externally meshing planetary gear set, including a fourth sun gear, a fourth planet carrier, and a fourth ring gear; the third sun gear serves as the input component of the reduction differential mechanism, the third planet carrier serves as the left output component of the reduction differential mechanism and is fixedly connected to the left half-shaft, the third ring gear is fixedly connected to the fourth sun gear, the fourth ring gear remains fixed, and the fourth planet carrier serves as the right output component of the reduction differential mechanism and is fixedly connected to the right half-shaft; and the structural characteristic parameters k3 and k4 of the third and fourth planetary gear sets satisfy: k4 = 2 + 1 / k3.

[0013] Preferably, the third planetary gear set includes a third sun gear, a third planet carrier, and a third ring gear; the fourth planetary gear set is a single-row, double-star, internally and externally meshing planetary gear set, including a fourth sun gear, a fourth planet carrier, and a fourth ring gear; the third sun gear serves as the input component of the reduction differential mechanism, the third planet carrier serves as the left output component of the reduction differential mechanism and is fixedly connected to the left half-shaft, the third ring gear is fixedly connected to the fourth planet carrier, the fourth ring gear remains fixed, and the fourth sun gear serves as the right output component of the reduction differential mechanism and is fixedly connected to the right half-shaft; and the structural characteristic parameters k3 and k4 of the third and fourth planetary gear sets satisfy: k4 = (1 + 2k3) / (1 + k3).

[0014] Preferably, the third planetary gear set is a double-row single-star meshing planetary gear set, and the fourth planetary gear set is arranged in the right wheel hub.

[0015] The positive effects of the above technical solution are: This invention provides a dual-motor, all-planetary-gear coaxial electric drive axle for heavy-duty trucks. The three-speed planetary transmission mechanism uses only four planetary gear sets and two shifting elements, resulting in a compact size, balanced mass distribution, and high adaptability. Since each motor and its associated shifting element can directly utilize the three forward gears of the transmission mechanism, it can achieve dual-motor or single-motor-three-gear drive of the vehicle. Therefore, even if one motor fails and disengages from the planetary gear set, the other motor can still drive the vehicle using the three gears of the transmission mechanism, demonstrating high fault tolerance. Furthermore, it allows for free selection of either motor to drive the vehicle when it is unloaded or partially loaded, thereby improving efficiency and ensuring that the lifespan of the two motors is essentially synchronized, thus guaranteeing the electric drive axle's B10 lifespan of millions of kilometers. During gear shifting, one motor and its associated shifting element remain in the old gear to continue driving the vehicle, while the other motor and its associated shifting element disengage and engage a new gear to participate in driving the vehicle, then remain in the old gear. The motor and its shifting elements can then shift into new gears to drive the vehicle, meaning the two motors can be engaged in different gears to drive the vehicle, thus achieving uninterrupted power shifting. The output component of the transmission mechanism is fixedly connected to the third input shaft and the input component of the reduction differential mechanism. Power can be directly transmitted to the reduction differential mechanism from the third input shaft. Thus, after setting the speed ratio achieved by the reduction differential mechanism to a 3rd gear ratio, a direct drive is realized, ensuring high transmission efficiency at high vehicle speeds. Moreover, the 1st and 2nd gear ratios only require two planetary gear sets. The number of planetary gear sets is controlled to two, and the structural characteristic parameters of the planetary gear sets are limited to about 2.2 in the existing technology, so that they and the two shifting elements can be configured in the rotor bracket cavity of the two motors, and a larger 1st gear ratio can be achieved than in the existing technology. The reduction differential mechanism uses the third and fourth planetary gear sets to achieve the 3rd gear ratio and differential function, which, together with the transmission mechanism, realizes a three-speed transmission mechanism, thus providing better overall performance. Attached Figure Description

[0016] Figure 1 The diagram shown is a schematic of an electric drive bridge with two shifting elements engaged in the same gear position according to a first specific embodiment.

[0017] Figure 2 The diagram shown is a schematic of an electric drive bridge with two shifting elements engaged in different gears according to a first specific embodiment.

[0018] Figure 3 The diagram shown is a schematic of an electric drive bridge with two shifting elements engaged in different neutral gears according to a first specific embodiment.

[0019] Figure 4 The diagram shown is a schematic of an electric drive bridge with two shifting elements engaged in the same neutral gear according to a first specific embodiment.

[0020] Figure 5 The diagram shows an electric drive bridge in the single-motor drive mode of the first embodiment, where the first motor operates.

[0021] Figure 6 The diagram shows an electric drive bridge in the single-motor drive mode of the first specific embodiment, in which the second motor operates.

[0022] Figure 7 The diagram shown is a schematic of the electric drive axle in neutral (N) gear according to the second specific embodiment.

[0023] Figure 8 The diagram shown is a schematic of a dual-motor electric drive bridge in the second specific embodiment with the motor in first gear.

[0024] Figure 9 The diagram shows an electric drive bridge with two shifting elements respectively engaged in 1st and 2nd gear according to the second specific embodiment.

[0025] Figure 10 The diagram shown is a schematic of a dual-motor electric drive bridge with two gears in the second specific embodiment.

[0026] Figure 11 The diagram shows an electric drive bridge with two shifting elements respectively engaged in 2nd and 3rd gear according to the second specific embodiment.

[0027] Figure 12 The diagram shown is a schematic of a dual-motor electric drive bridge with three gears in the second specific embodiment.

[0028] Figure 13 The diagram shown is a schematic of the electric drive bridge in the third specific embodiment.

[0029] Figure 14 The diagram shown is a schematic of the electric drive bridge in the fourth specific embodiment.

[0030] Figure 15 The diagram shown is a schematic of the electric drive bridge in the fifth specific embodiment.

[0031] Figure 16 The diagram shown is a schematic of the electric drive bridge in the sixth specific embodiment.

[0032] Figure 17 The diagram shown is a schematic of the electric drive bridge in the seventh specific embodiment.

[0033] Symbol explanation: 10 and 11 represent the bridge body and the right bridge pipe, respectively; 21 and 211 are the first motor and its rotor bracket, respectively; 22 and 221 are the second motor and its rotor bracket, respectively; 30, 301, 302, 303, and 304 are respectively the speed change mechanism and its first input shaft, second input shaft, third input shaft, and output component; 3011, 3021, and 3031 are the shift teeth for the first, second, and third input shafts, respectively. 31, 311, 312, and 313 are respectively the first planetary gear set, the first sun gear, the first planet carrier, and the first gear ring; 32, 321, 322, and 323 are respectively the second planetary arrangement, the second sun gear, the second planetary carrier, and the second gear ring; 33 and 331 are the first shift element and its shift gear, respectively; 34 and 341 are the second shift element and its shift gear, respectively; 40, 401, 402, and 403 are respectively the reduction differential mechanism and its input component, left output component, and right output component; 41, 411, 412, 413, and 4131 are the third planetary gear set, the third sun gear, the third planetary carrier, the third gear ring, and the third gear ring shaft, respectively. 42, 421, 422, and 423 are respectively the fourth planetary arrangement, the fourth sun gear, the fourth planetary carrier, and the fourth gear ring; 51 and 52 are the left and right half-axis, respectively; 61, 62, and 621 represent the left wheel, right wheel, and right hub, respectively. Detailed Implementation

[0034] To more clearly describe the technical content of the present invention, further description is provided below in conjunction with specific embodiments. Preferred embodiments of the present invention are described below. It should be understood that the preferred embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0035] In the description of this invention, it should be understood that the terms "left," "right," etc., indicating orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. The accompanying schematic diagram of the electric drive bridge only shows the "upper" half of the electric drive bridge; the lower half, which is not shown, is constructed symmetrically with the upper half.

[0036] The planetary gear sets involved in this invention mainly fall into three types. The first is the basic planetary gear set, the simplest in structure and the most widely used, including a sun gear, a ring gear, and a planet carrier, as well as multiple planet gears rotatably supported on the planet carrier and simultaneously meshing with both the sun gear and the ring gear. For this type of planetary gear set, the specific type will not be specifically specified. Furthermore, since the planet gears are only internal components of the planetary gear set and are not directly connected to the outside, the description of the components involved in the planetary gear set refers to one of the sun gear, the ring gear, and the planet carrier. The second type is a single-row, double-star, internally and externally meshing planetary gear set, which has multiple planet gear sets between the sun gear and the ring gear. Each planet gear set includes two planet gears rotatably supported on the planet carrier and meshing with each other; one planet gear meshes with the sun gear, and the other planet gear meshes with the ring gear. The third type is a double-row, single-star, internally and externally meshing planetary gear set, where the planet gears employ double gears, with the two gears meshing with the sun gear and the ring gear, respectively. Those skilled in the art will recognize that the structural characteristic parameters, kinematics, and dynamic characteristics of the above three types of planetary gear sets are already existing technology.

[0037] Furthermore, in the description of planetary gear sets that relates to this invention, "keeping fixed" means that the component is fixedly connected to the associated housing to remain stationary and not rotate, and "fixedly connected" means that the two components of two planetary gear sets rotate as a whole and at the same speed.

[0038] Figure 1 The diagram shown is a schematic of an electric drive axle with two shifting elements engaged in the same gear according to a first specific embodiment. Figure 2 The diagram shown is a schematic of an electric drive bridge with two shifting elements engaged in different gears according to a first specific embodiment. Figure 1 and Figure 2As shown, an electric drive axle for a heavy-duty vehicle includes: an axle body 10; a first motor 21, a second motor 22, and a planetary transmission mechanism mounted on and coaxially arranged on the axle body 10; the planetary transmission mechanism is provided with 1st gear, 2nd gear, and 3rd gear, and includes a transmission mechanism 30 and a reduction differential mechanism 40; the transmission mechanism 30 is provided with a first input shaft 301, a second input shaft 302, a third input shaft 303, and an output component 304, and includes a first planetary gear set 31, a second planetary gear set 32, a first shift element 33, and a second shift element 34; the output component 304 is fixedly connected to the third input shaft 303 and the input component 401 of the reduction differential mechanism; the first shift element 33 and the second shift element 34 are configured to connect the first motor rotor bracket 211 and the second motor rotor bracket 22... 1. The first motor rotor bracket 211 and the second motor rotor bracket 221 can be simultaneously connected to one of the first input shaft 301, the second input shaft 302 and the third input shaft 303 to achieve dual motor drive at the same gear. Alternatively, the first motor rotor bracket 211 and the second motor rotor bracket 221 can be simultaneously connected to two of the first input shaft 301, the second input shaft 302 and the third input shaft 303 to achieve dual motor drive at different gears. The reduction differential mechanism 40 achieves a reduction ratio equal to the 3rd gear ratio and includes a third planetary gear set 41 and a fourth planetary gear set 42 connected to each other. One component of the third planetary gear set 41 serves as the left output component 402 of the reduction differential mechanism and is connected to the left wheel 61 through the left half shaft 51. One component of the fourth planetary gear set 42 serves as the right output component 403 of the reduction differential mechanism and is connected to the right wheel 62 through the right half shaft 52.

[0039] In the design of the electric drive axle system architecture, the view that "one of the two drive motors is the main drive motor and the other is the auxiliary drive motor" was abandoned. Instead, the function of the two drive motors was defined as "both can drive the vehicle independently when the vehicle is unloaded or half-loaded, and drive the vehicle together when the vehicle is fully loaded". In other words, the two drive motors are equal, free and can cooperate amicably.

[0040] The planetary transmission system architecture is designed to ensure that each drive motor can directly engage all gears of the transmission mechanism, and that two drive motors can simultaneously engage the same gear, achieving the basic requirement of uninterrupted power shifting. In the coaxial electric drive axle, the drive motor and planetary transmission mechanism are coaxial with the wheels. The difference between the wheel radius and ground clearance determines the diameter of the drive motor, while the distance between the inner sides of the left and right airbags of the air suspension matched to the electric drive axle determines the available axial space for the drive motor and transmission mechanism. Considering the axial space occupied by the high-power drive motor, the number of planetary gear sets and shifting elements included in the transmission mechanism should be minimized, and the structural characteristic parameters of the planetary gear set should not exceed 2.2 of existing technologies to be able to be integrated into the motor rotor cavity. The transmission mechanism should have at least three gears to better meet the power and economy requirements of heavy-duty trucks.

[0041] To achieve the above objectives, it is crucial to ensure that the two drive motors operate equally, freely, and cooperatively. Three input shafts and two shifting elements are installed at the input end of the transmission mechanism. The three input shafts correspond to three gears. Each drive motor can directly connect to any one of the three input shafts using a shifting element, inputting power into the transmission mechanism. This allows each drive motor to directly utilize all three gears. When the two drive motors are in different gears (i.e., they input power to the transmission mechanism through adjacent input shafts), it ensures that at least one motor drives the vehicle during gear shifting, achieving uninterrupted power delivery. When the two drive motors are in the same gear, they operate in tandem, providing simultaneous drive. The vehicle's transmission mechanism output component is fixedly connected to the third input shaft and the input component of the reduction differential mechanism. Power can be directly transmitted from the third input shaft to the reduction differential mechanism. Thus, after setting the speed ratio achieved by the reduction differential mechanism to a 3-speed ratio, a direct drive is realized. The 1st and 2nd gear ratios only require two planetary gear sets. The number of planetary gear sets is controlled to two, and the structural characteristic parameters of the planetary gear sets are limited to about 2.2 in the prior art, so that they and the two shifting elements can be arranged in the rotor bracket cavity of the two motors. The reduction differential mechanism only uses two planetary gear sets to achieve a 3-speed ratio of about 10 and the function of the differential. After cooperating with the transmission mechanism, it realizes the three gears of the transmission mechanism.

[0042] like Figure 1 As shown, the first input shaft 301, the second input shaft 302, and the third input shaft 303 are coaxially arranged at intervals. The first shifting element 33 is a sliding sleeve inserted into the first motor rotor bracket 211. When it moves axially in one direction, it connects the first motor rotor bracket 211 with the first input shaft 301, the second input shaft 302, and the third input shaft 303 in sequence, respectively achieving gear 1, gear 2, and gear 3. The second shifting element 34 is a sliding sleeve inserted into the second motor rotor bracket 221. When it moves axially in one direction, it connects the second motor rotor bracket 221 with the first input shaft 301, the second input shaft 302, and the third input shaft 303 in sequence, respectively achieving gear 1, gear 2, and gear 3.

[0043] The first shifting element 33 is installed in the central hole of the first motor rotor bracket 211 and rotates integrally with it. It can also move axially relative to the latter, connecting to the first input shaft 301, the second input shaft 302, and the third input shaft 303 in three positions respectively. This allows the power from the first motor 21 to be transmitted to the transmission mechanism 30 via corresponding components for deceleration and torque amplification before output. The first shifting element 33 is a three-position shifting element, driven by only one electric actuator or other type of actuator. While this simplifies the system, it imposes orderly requirements on the combination and connection of the planetary gear sets. Therefore, only certain planetary gear set combinations and connection schemes are suitable for its use. The first shifting element 33 and the second shifting element 34 are preferably constructed as asynchronous claw teeth. The installation of the second shifting element 34 is similar to its action on the first shifting element 33; it is also a three-position shifting element and is also preferably constructed as asynchronous claw teeth, which will not be described further here.

[0044] like Figure 1 As shown, the axial lengths of the first input shaft shifting tooth 3011, the second input shaft shifting tooth 3021, and the third input shaft shifting tooth 3031 are all set to be greater than the sum of the axial lengths of the first shifting element shifting tooth 331 and the second shifting element shifting tooth 341. Because the power of two motors needs to be transmitted simultaneously, each input shaft must be able to connect with the first motor rotor bracket 211 and the second motor rotor bracket 221 at the same time. That is, the first input shaft shifting tooth 3011, the second input shaft shifting tooth 3021, or the third input shaft shifting tooth 3031 must be able to engage with the first shifting element shifting tooth 331 and the second shifting element shifting tooth 341 at the same time. Considering the slight axial clearance between the latter two, the axial lengths of the input shaft shifting teeth 3011, 3021, and 3031 are all set to be greater than the sum of the axial lengths of the first shifting element shifting tooth 331 and the second shifting element shifting tooth 341.

[0045] Figure 3 The diagram shown is a schematic of an electric drive bridge with two shifting elements engaged in different neutral gears according to a first specific embodiment. Figure 4 The diagram shown is a schematic of an electric drive bridge with two shifting elements engaged in the same neutral gear according to a first specific embodiment. Figure 5 The diagram shows an electric drive bridge in the single-motor drive mode of the first embodiment, where the first motor operates. Figure 6 The diagram shows an electric drive bridge in the single-motor drive mode of the first specific embodiment, in which the second motor operates.

[0046] like Figures 3 to 6As shown, the axial clearance between the first input shaft shift tooth 3011 and the second input shaft shift tooth 3021, and the axial clearance between the second input shaft shift tooth 3021 and the third input shaft shift tooth 3031, are both set to be greater than the axial length of the first shift element shift tooth 331 or the second shift element shift tooth 341. The axial clearance of the outer end of the first input shaft shift tooth 3011 away from the second input shaft shift tooth 3021 is set to be greater than the sum of the axial lengths of the first shift element shift tooth 331 and the second shift element shift tooth 341. The axial clearance of the outer end of the third input shaft shift tooth 3031 away from the second input shaft shift tooth 3021 is set to be greater than the axial length of the first shift element shift tooth 331 or the second shift element shift tooth 341.

[0047] like Figure 3 As shown, since the shifting element needs to be briefly in neutral during gear shifting, there is an axial clearance between the first input shaft shifting tooth 3011 and the second input shaft shifting tooth 3021, and between the second input shaft shifting tooth 3021 and the third input shaft shifting tooth 3031. Since it is a power shift, the first shifting element shifting tooth 331 and the second shifting element shifting tooth 341 will not move to this position at the same time. The axial clearance only needs to be sufficient to allow either the first shifting element shifting tooth 331 or the second shifting element shifting tooth 341 to move to this position. It can be set to be slightly larger than the axial length of the first shifting element shifting tooth 331 or the second shifting element shifting tooth 341. This also helps to shorten the overall axial length of the shifting mechanism.

[0048] like Figure 4 As shown, since the electric drive axle is in neutral (N) when parked or towed in case of a breakdown, sufficient axial space must be left on the outer side of the end of the first input shaft shift tooth 3011 furthest from the second input shaft shift tooth 3021 to accommodate the simultaneous movement of the first shift element shift tooth 331 and the second shift element shift tooth 341 to this position to engage neutral. Considering the small gaps between the shift teeth, the axial clearance at this point is set to be greater than the sum of the axial lengths of the first shift element shift tooth 331 and the second shift element shift tooth 341. Obviously, this axial clearance is also the starting and ending point of the operation of the first shift element 33 and the second shift element 34. When the vehicle starts, the two shift elements begin to move axially from this point, and when the vehicle is turned off, the two shift elements return to this point.

[0049] In single-motor drive mode, whether the vehicle is driving normally under no-load conditions, using one motor to drive the vehicle during a single no-load trip and the other motor to drive the vehicle during the next no-load trip (i.e., alternating between the two motors for efficiency and lifespan purposes where only partial power is needed for up to 70% of the trip), or when one motor fails and is disconnected from the transmission mechanism to drive the vehicle solely with the other motor, the shifting element corresponding to the non-working motor should remain in a suitable neutral position without hindering the other working shifting element from freely engaging the three gears. Since the two shifting elements are coaxially configured, when the motor corresponding to the shifting element located radially outward is working, the shifting teeth of the shifting element located radially inward remain at the axial clearance outside the end of the aforementioned first input shaft shifting tooth 3011, away from the second input shaft shifting tooth 3021. The shifting element located radially outward will then move axially without obstruction to engage the three gears.

[0050] When only the motor corresponding to the shifting element located on the radially inner side is working, the shifting teeth of the shifting element located on the radially outer side must be maintained at the axial clearance of the outer end of the third input shaft shifting tooth 3031 away from the second input shaft shifting tooth 3021. The shifting element located on the radially inner side will move freely axially to engage the three gears without obstruction. Moreover, since only the shifting teeth of the radially outer side will move to this position, it will not happen that the shifting teeth of both shifting elements move to this position at the same time. Considering an appropriate small clearance, the axial clearance of the outer end of the third input shaft shifting tooth 3031 away from the second input shaft shifting tooth 3021 is set to be greater than the axial length of the first shifting tooth 331 or the second shifting tooth 341.

[0051] like Figure 5 As shown, in the two coaxially configured shifting elements, the second shifting element 34 is located on the radially outer side, and the first shifting element 33 is located on the radially inner side. In order to ensure that the first shifting element 33 can engage three gears when only the first motor 21 is working, the shifting tooth 341 of the second shifting element is axially moved to the axial gap on the outer side of the end of the third input shaft shifting tooth 3031 away from the second input shaft shifting tooth 3021, which also disengages the second motor 22 from the transmission mechanism and puts it into rest, thus eliminating drag loss.

[0052] like Figure 6 As shown, if only the second motor 22 is working and the first motor 21 is idle, then obviously the shifting gear 331 of the first shifting element will move to the position shown. Figure 4 The axial gap at the outer end of the first input shaft shift tooth 3011, which is far from the second input shaft shift tooth 3021, ensures that the second shift element 34 can smoothly engage all three gears.

[0053] The working principle of the electric drive axle will be further explained below with reference to a specific transmission mechanism.

[0054] Figure 7 The diagram shown is a schematic of the electric drive bridge according to a second specific embodiment. Figure 7 As shown, the first planetary gear set 31 includes a first sun gear 311, a first planet carrier 312, and a first ring gear 313; the second planetary gear set 32 ​​includes a second sun gear 321, a second planet carrier 322, and a second ring gear 323; the first ring gear 313 and the second sun gear 321 are both fixed, the first sun gear 311 is fixedly connected to the first input shaft 301 of the transmission mechanism, the second ring gear 323 is fixedly connected to the second input shaft 302 of the transmission mechanism, and the first planet carrier 312 and the second planet carrier 322 are fixedly connected as the output component 304 of the transmission mechanism.

[0055] The gear ratio consists of two parts: the first part is the gear ratio of the transmission mechanism, and the second part is the three-speed ratio achieved by the reduction differential mechanism. Referring to existing technologies, the three speed ratios are 22.2 / 15.4 / 9.2. If the three-speed ratio reaches 9.2 and the gear difference is not less than 1.6, then the three transmission ratios are 2.56 / 1.6 / 1, and the three gear ratios are 23.6 / 14.7 / 9.2. Typically, the gear difference between 1st and 2nd gear is appropriately increased to meet the maximum climbing gradient requirement; that is, the 1st gear ratio will be slightly larger than 23.6, and the first transmission ratio will be slightly larger than 2.56. Based on this, a feasible planetary gear set combination scheme is selected, ensuring that the planetary gear set structural characteristic parameters are not greater than 2.2 so that it can be configured within the rotor bracket cavity.

[0056] For gear ratio sequences with small gear differences, such as around 1.65, it is considered to set up a planetary gear set for each gear to achieve the required gear ratio, and to use a single shifting element to achieve three gears. Therefore, the arrangement and connection of the planetary gear set have specific requirements, that is, the components of the planetary gear set can be routed to the required positions to connect with other components.

[0057] With power input to the first sun gear 311, the first ring gear 313 remains fixed, the first planetary carrier 312 outputs power, and the first planetary gear set 31 can achieve a speed ratio of 1+k1. If k1=1.65 is set, a first gear ratio of 2.65 can be achieved.

[0058] With the second sun gear 321 fixed, the second ring gear 323 as input, and the second planetary carrier 322 as output, the second planetary gear set 32 ​​can achieve a speed ratio of 1+1 / k2. If k2=1.65 is set, a 2-speed gear ratio of 1.61 can be achieved.

[0059] Since the two planetary gear sets have the same structural characteristic parameters, the transmission mechanism can be constructed using planetary gear sets with identical tooth profile parameters except for the tooth width, thus simplifying manufacturing. The resulting gear ratios for 1st, 2nd, and 3rd gears are 2.65, 1.61, and 1, respectively.

[0060] Furthermore, if the structural characteristic parameters of the first planetary gear set 31 adopt the existing value of 2.2, a first gear ratio of 3.2 can be achieved, resulting in greater wheel-end output torque and better climbing performance.

[0061] Two planetary gear sets are combined, with the first sun gear 311 fixedly connected to the first input shaft 301, and the second ring gear 323 fixedly connected to the second input shaft 302. The first planet carrier 312 and the second planet carrier 322, which are fixedly connected to each other, serve as output components 304 and are fixedly connected to the third input shaft 301. The first sun gear 311, the second ring gear 323, and the fixedly connected first planet carrier 312 and second planet carrier 322, corresponding to gears 1, 2, and 3, are arranged in an orderly manner, laying the foundation for using a three-position shifting element to achieve three gears. That is, when a shifting element moves axially in one direction, it can sequentially engage gears 1, 2, and 3.

[0062] The following describes the complete parking start-up acceleration process of the electric drive axle from neutral (N) to first gear and then to third gear. The deceleration and downshifting process is the reverse of the upshifting and acceleration process, and so on, so it will not be described in detail here.

[0063] like Figure 7 As shown, in the parking state, the shift teeth 331 and 341 of the two shift elements have been axially moved to the right side of the first input shaft shift tooth 3011, realizing the N gear.

[0064] Figure 8 The diagram shown is a schematic of a dual-motor electric drive bridge in the second specific embodiment, with the motor engaged in first gear. Figure 8 As shown, the shifting teeth 331 and 341 of the two shifting elements have both moved axially and engaged with the shifting tooth 3011 of the first input shaft, realizing the engagement of first gear. The power of the two motors is transmitted from the rotor brackets 211 and 221 to the shifting teeth 331 and 341 of the two shifting elements. After converging on the shifting tooth 3011 of the first input shaft, it is transmitted to the first sun gear 311. After being reduced in speed by the first planetary gear set 31, it is output from the first planetary carrier 312 to the input component 401 of the reduction differential mechanism. After being reduced in speed and split by the reduction differential mechanism 40, it is transmitted to the left half shaft 51 and the right half shaft 52, thereby driving the left wheel 61 and the right wheel 62.

[0065] Figure 9 The diagram shows an electric drive axle with two shifting elements respectively engaged in 1st and 2nd gear according to a second specific embodiment. Figure 9As shown, during the shifting process from 1st to 2nd gear, the shifting gear 331 of the first shifting element is still engaged with the shifting gear 3011 of the first input shaft, remaining in 1st gear. The power of the first motor 21 is still transmitted from the rotor bracket 211 to the first sun gear 311, and after being reduced by the first planetary gear set 31, it is output from the first planetary carrier 312 to the input component 401 of the reduction differential mechanism. After being reduced and split by the reduction differential mechanism 40, it drives the left wheel 61 and the right wheel 62. At the same time, the torque of the second motor 21 decreases to zero, the shifting gear 341 of the second shifting element moves axially and engages with the shifting gear 3021 of the second input shaft, and is engaged in second gear. The second motor 22 increases its power, which is transmitted from the rotor bracket 221 to the second gear ring 323. After being reduced in speed by the second planetary gear set 32, it is output from the second planetary carrier 322 to the input component 401 of the reduction differential mechanism. After merging with the power transmitted here by the first motor 21, it is reduced in speed and split by the reduction differential mechanism 40 and then drives the left wheel 61 and the right wheel 62.

[0066] Figure 10 The diagram shown is a schematic of a dual-motor electric drive axle with two gears in the second specific embodiment. Figure 10 As shown, to complete the shift from 1st to 2nd gear, the torque of the first motor 21 is reduced to zero. The shifting gear 331 of the first shifting element moves axially and engages with the shifting gear 3021 of the second input shaft. The first motor 21 increases its power, which is transmitted from the rotor bracket 211 to the shifting gear 3021 of the second input shaft. After merging with the power transmitted from the second motor 22, the power is reduced and split by the reduction differential mechanism 40 and then drives the left wheel 51 and the right wheel 52. At this time, the shifting gears 331 and 341 of both shifting elements are engaged with the shifting gear 3021 of the second input shaft, realizing the shift to 2nd gear. The power of the two motors is transmitted from the rotor brackets 211 and 221 to the shifting teeth 331 and 341 of the two shifting elements. After converging on the shifting teeth 3021 of the second input shaft, it is transmitted to the second gear ring 323. After being reduced in speed by the second planetary gear set 32, it is output from the second planetary carrier 322 to the input component 401 of the reduction differential mechanism. After being reduced in speed and split by the reduction differential mechanism 40, it is transmitted to the left half shaft 51 and the right half shaft 52, thereby driving the left wheel 61 and the right wheel 62.

[0067] Figure 11 The diagram shows an electric drive axle with two shifting elements respectively engaged in 2nd and 3rd gear according to a second specific embodiment. Figure 11As shown, during the shift from 2nd to 3rd gear, the first shift element shift gear 331 remains engaged with the second input shaft shift gear 3021, maintaining 2nd gear. The power of the first motor 21 is still transmitted from the rotor carrier 211 to the second gear ring 323, and after being reduced in speed by the second planetary gear set 32, it is output from the second planetary carrier 322 to the input component 401 of the reduction differential mechanism. After being reduced in speed by the reduction differential mechanism 40, it drives the left wheel 61 and the right wheel 62. At the same time, the torque of the second motor 21 decreases to zero, the second shift element shift gear 341 moves axially and engages with the third input shaft shift gear 3031, engaging 3rd gear. The second motor 22 increases its power, which is transmitted from the rotor carrier 221 to the input component 401 of the reduction differential mechanism. After merging with the power transmitted from the first motor 21, it is reduced in speed by the reduction differential mechanism 40 and then drives the left wheel 61 and the right wheel 62.

[0068] Figure 12 The diagram shown is a schematic of a dual-motor electric drive axle with three gears in the second specific embodiment. Figure 12 As shown, to complete the shift from 2nd to 3rd gear, the torque of the first motor 21 is reduced to zero. The shifting gear 331 of the first shifting element moves axially and engages with the shifting gear 3031 of the third input shaft. The first motor 21 increases its power, which is transmitted from the rotor bracket 211 to the input component 401 of the reduction differential mechanism. After merging with the power transmitted from the second motor 22, the power is reduced and split by the reduction differential mechanism 40 to drive the left wheel 61 and the right wheel 62. At this time, the shifting gears 331 and 341 of both shifting elements are engaged with the shifting gear 3031 of the third input shaft, realizing the shift to 3rd gear. The power of the two motors is transmitted from the rotor brackets 211 and 221 to the shifting teeth 331 and 341 of the two shifting elements. After converging on the shifting teeth 3031 of the third input shaft, it is directly transmitted to the input component 401 of the reduction differential mechanism. That is, it is directly output to the reduction differential mechanism 40 without passing through the two planetary gear sets 31 and 32. Therefore, the 3-speed transmission has high efficiency and meets the working conditions of heavy trucks that usually run at high speeds for a long time in the highest gear.

[0069] For a single-motor drive mode, if we do not consider power shifting, that is, when the other motor is completely idle and only one motor is working, then as long as the shifting element corresponding to the idle motor is axially moved to the appropriate position to engage neutral, it will not hinder the axial movement of the shifting element corresponding to the other working motor to engage three gears.

[0070] like Figure 5 As shown, when the first motor 21 is working and the second motor 22 is resting, the second shifting element 34 moves axially to the neutral position on the left side of the shifting gear 3031 on the third input shaft. The first shifting element 34 can move freely axially to engage three gears, and the first motor 21 can drive the vehicle using the three gears.

[0071] like Figure 6 As shown, when the first motor 21 is at rest and the second motor 22 is working, the first shifting element 33 moves axially to the neutral position on the right side of the first input shaft shifting gear 3011, the second shifting element 34 can move freely axially to engage three gears, and the second motor 22 can engage three gears to drive the vehicle.

[0072] Figure 13 The diagram shown is a schematic of the electric drive bridge in the third specific embodiment. Figure 13 As shown, the first planetary gear set 31 is a single-row, double-star, internally and externally meshing planetary gear set, including a first sun gear 311, a first planet carrier 312, and a first ring gear 313; the second planetary gear set 32 ​​includes a second sun gear 321, a second planet carrier 322, and a second ring gear 323; both the first sun gear 311 and the second sun gear 321 are fixed, the first planet carrier 312 is fixedly connected to the first input shaft 301, the second ring gear 323 is fixedly connected to the second input shaft 302, and the first ring gear 313 is fixedly connected to the second planet carrier 322 as the output component 304 of the transmission mechanism.

[0073] When the first planetary carrier 312 receives power, the first sun gear 311 remains fixed, and the first ring gear 313 outputs power, the first planetary gear set 31 can achieve a speed ratio of k1 / (k1-1). If k1=1.5 is set, then the achieved first gear ratio is 3.

[0074] When the second sun gear 321 receives power, the second ring gear 323 remains fixed, and the second planetary carrier 322 outputs power, the second planetary gear set 32 ​​can achieve a speed ratio of 1+1 / k2. If k2=1.5 is set, then the achieved 2nd gear ratio is 1.67.

[0075] Therefore, the three gear ratios achieved by the transmission mechanism are 3, 1.67, and 1. Since the structural characteristic parameters of the two planetary gear sets are relatively small, they can be embedded in the inner cavity of the rotor bracket, meeting the requirements of a compact arrangement.

[0076] In the above specific embodiments, only one corresponding planetary gear set participates in transmitting power at each gear of the transmission mechanism, while the other planetary gear set idles, resulting in high transmission efficiency. Moreover, considering the structural characteristic parameter constraints imposed by arranging the planetary gear set inside the motor rotor cavity, as well as the requirement to meet the shift sequence, only the above two solutions are feasible.

[0077] In addition, when the first gear ratio is relatively large, two planetary gear sets can be connected in series. The structural characteristic parameters of each planetary gear set are therefore smaller, so the planetary gear sets can be arranged in the inner cavity of the rotor bracket.

[0078] Figure 14 The diagram shown is a schematic of the electric drive bridge in the fourth specific embodiment. Figure 14As shown, the first planetary gear set 31 includes a first sun gear 311, a first planet carrier 312, and a first ring gear 313; the second planetary gear set 32 ​​includes a second sun gear 321, a second planet carrier 322, and a second ring gear 323; the first ring gear 313 and the second ring gear 323 are both fixed, the first planet carrier 312 is fixedly connected to the second sun gear 321, the first sun gear 311 is fixedly connected to the first input shaft 301, the second sun gear 321 is fixedly connected to the second input shaft 302, and the second planet carrier 322 serves as the output component 304 of the transmission mechanism.

[0079] When the first sun gear 311 receives power, the first ring gear 313 remains fixed, the first planetary carrier 312 outputs power to the second sun gear 321, the second ring gear 323 remains fixed, and the second planetary carrier 322 outputs power to the input component 401 of the reduction differential mechanism. The speed ratio that can be achieved by connecting the two planetary gear sets 31 and 32 in series is (1+k1)(1+k2). If k1=k2=1.5 is set, then the first gear ratio is 6.25.

[0080] When power is input to the second sun gear 321, the second ring gear 323 remains fixed, and the second planetary carrier 322 outputs power. The achievable speed ratio of the second planetary gear set 32 ​​is 1+k2. When k2=1.5, the 2nd gear ratio is 2.5. At this time, the first planetary gear set 31 idles and does not transmit power; only the second planetary gear set 32 ​​participates in the operation.

[0081] Since the two planetary gear sets have the same structural characteristic parameters, a planetary gear set with identical tooth profile parameters (except for tooth width) can be used to construct the transmission mechanism, thus simplifying manufacturing. This results in gear ratios of 6.25, 2.5, and 1 for 1st, 2nd, and 3rd gears, respectively.

[0082] Figure 15 The diagram shown is a schematic of the electric drive bridge in the fifth specific embodiment. Figure 15 As shown, the first planetary gear set 31 is a single-row, double-star, internally and externally meshing planetary gear set, including a first sun gear 311, a first planet carrier 312, and a first gear ring 313; the second planetary gear set 32 ​​is a single-row, double-star, internally and externally meshing planetary gear set, including a second sun gear 321, a second planet carrier 322, and a second gear ring 323; the first planet carrier 312 and the second planet carrier 322 are both fixed, the first gear ring 313 is fixedly connected to the second sun gear 321, the first sun gear 311 is fixedly connected to the first input shaft 301, the second sun gear 321 is fixedly connected to the second input shaft 302, and the second gear ring 323 serves as the output component 304 of the transmission mechanism.

[0083] When the first sun gear 311 receives power, the first planetary carrier 312 remains fixed, the first ring gear 313 outputs power to the second sun gear 321, the second planetary carrier 322 remains fixed, and the second ring gear 323 outputs power to the input component 401 of the reduction differential mechanism. The speed ratio that can be achieved after the two planetary gear sets 31 and 32 are connected in series is k1k2. If k1=k2=2, then the first gear ratio is 4.

[0084] When power is input to the second sun gear 321, the second planetary carrier 322 remains fixed, and the second ring gear 323 outputs power. The achievable gear ratio of the second planetary gear set 32 ​​is k2. When k2=2, the 2nd gear ratio is 2. At this time, the first planetary gear set 31 idles and does not transmit power; only the second planetary gear set 32 ​​participates in the operation.

[0085] As mentioned before, since the structural characteristic parameters are the same, the two planetary gear sets can be further constructed using planetary gear sets with exactly the same tooth profile parameters, thus simplifying manufacturing. This results in the gear ratios of 1st, 2nd, and 3rd gears being 4, 2, and 1, respectively.

[0086] For the transmission mechanism 30, due to the required speed ratio range and the arrangement and connection of the planetary gear set, the possible solutions have all been as described above.

[0087] Typically, a combination of a pair of main reduction gear sets and a bevel gear differential is used as the final drive. However, since the reduction ratio that the main reduction gear set can achieve is limited and difficult to exceed 6, and the shape of the bevel gear differential is not easy to integrate, it is considered to use two planetary gear sets to construct a reduction differential mechanism that can achieve a larger reduction ratio and has differential function. Moreover, the reduction ratio that two planetary gear sets can achieve can reach 3 gear ratios, thus matching the gear ratio of the transmission mechanism, and facilitating higher transmission efficiency in the highest gear.

[0088] like Figure 7 As shown, in the first specific embodiment of the deceleration differential mechanism 40, the third planetary gear set 41 includes a third sun gear 411, a third planet carrier 412, and a third ring gear 413; the fourth planetary gear set 42 is a single-row double-star internal and external meshing planetary gear set, including a fourth sun gear 421, a fourth planet carrier 422, and a fourth ring gear 423; the third sun gear 411 serves as the input component 401 of the deceleration differential mechanism, the third planet carrier 412 serves as the left output component 402 of the deceleration differential mechanism and is fixedly connected to the left half-shaft 51, the third planet carrier 413 is fixedly connected to the fourth sun gear 421, the fourth ring gear 423 remains fixed, and the fourth planet carrier 422 serves as the right output component 403 of the deceleration differential mechanism and is fixedly connected to the right half-shaft 52; and the structural characteristic parameters k3 and k4 of the third planetary gear set 41 and the fourth planetary gear set 42 satisfy: k4=2+1 / k3.

[0089] The above conditions ensure that the output torques of the left output component 402 and the right output component 403 of the reduction differential mechanism are equal, satisfying the "differential speed, no torque difference" function of the differential. Under these conditions, the reduction ratio of the mechanism is calculated as follows: 1 + k3k4. Within the reasonable value range of 1.5 to 4.5 for k3 and k4, the maximum achievable reduction ratio is found to be 11, k3 = 9 / 2, k4 = 20 / 9. If the 3rd gear ratio is 9.2, then k3 = 18 / 5, k4 = 41 / 18, both within the reasonable value range. The third planetary gear set 41 and the fourth planetary gear set 42 should be specifically matched according to the above fractions to ensure that the structural characteristic parameter equations are fully satisfied.

[0090] Figure 7 , Figure 13 , Figure 14 and Figure 15 The transmission mechanism 30 shown can be used in conjunction with the first specific embodiment of the reduction differential mechanism 40, and the speed ratio of each gear of the planetary transmission mechanism is equal to the product of the speed ratio of each gear and the speed ratio of the third gear.

[0091] Figure 7 The transmission mechanism 30 shown can achieve gear ratios of 2.65, 1.61, and 1 for 1st, 2nd, and 3rd gears, respectively. When the reduction differential mechanism 40 achieves a 3rd gear ratio of 9.2, the gear ratios for the three gears are 24.4, 14.8, and 9.2, respectively. When the reduction differential mechanism 40 achieves a 3rd gear ratio of 11, the gear ratios for the three gears are 29.2, 17.7, and 11, respectively. This results in a 1st gear ratio greater than that of existing technologies.

[0092] Figure 13 The transmission mechanism 30 shown can achieve three gear ratios of 3, 1.67 and 1 respectively. When the third gear ratio achieved by the deceleration differential mechanism 40 is 9.2, the three gear ratios are 27.6, 15.4 and 9.2 respectively. When the third gear ratio achieved by the deceleration differential mechanism is 11, the three gear ratios are 33, 18.4 and 11 respectively. Obviously, a first gear ratio greater than that of the prior art is obtained.

[0093] Figure 14 The transmission mechanism 30 shown can achieve three gear ratios of 6.25, 2.5 and 1 respectively. When the reduction differential mechanism 40 achieves a 3rd gear ratio of 9.2, the three gear ratios are 57.5, 23 and 9.2 respectively. When the reduction differential mechanism 40 achieves a 3rd gear ratio of 11, the three gear ratios are 68.8, 27.5 and 11 respectively. Obviously, a 1st gear ratio greater than that of the prior art is obtained.

[0094] Figure 15The transmission mechanism 30 shown can achieve three gear ratios of 4, 2 and 1 respectively. When the third gear ratio achieved by the deceleration differential mechanism 40 is 9.2, the three gear ratios are 36.8, 18.4 and 9.2 respectively. When the third gear ratio achieved by the deceleration differential mechanism 40 is 11, the three gear ratios are 44, 22 and 11 respectively, thus obtaining a first gear ratio greater than that of the prior art.

[0095] like Figure 15 As shown, in the second specific embodiment of the deceleration differential mechanism 40, the third planetary gear set 41 includes a third sun gear 411, a third planet carrier 412, and a third ring gear 413; the fourth planetary gear set 42 is a single-row double-star internal and external meshing planetary gear set, including a fourth sun gear 421, a fourth planet carrier 422, and a fourth ring gear 423; the third sun gear 411 serves as the input component 401 of the deceleration differential mechanism, the third planet carrier 412 serves as the left output component 402 of the deceleration differential mechanism and is fixedly connected to the left half-shaft 51, the third ring gear 413 is fixedly connected to the fourth planet carrier 422, the fourth ring gear 423 remains fixed, and the fourth sun gear 421 serves as the right output component 403 of the deceleration differential mechanism and is fixedly connected to the right half-shaft 52; and the structural characteristic parameters k3 and k4 of the third planetary gear set 41 and the fourth planetary gear set 42 satisfy: k4 = (1 + 2k3) / (1 + k3).

[0096] The above conditions ensure that the output torques of the left output component 402 and the right output component 403 of the reduction differential mechanism are equal, and the reduction ratio obtained under these conditions is as follows: 1 + k3k4 / (k4 - 1). Within the reasonable value range of 1.5 to 4.5 for k3 and k4, the maximum achievable reduction ratio is found to be 11, k3 = 9 / 2, k4 = 20 / 11. If the 3rd gear ratio is 9.2, then k3 = 18 / 5, k4 = 41 / 23, both within the reasonable value range. The third planetary gear set 41 and the fourth planetary gear set 42 should be specifically matched according to the above fractions to ensure that the structural characteristic parameter equations are fully satisfied.

[0097] Figure 7 , Figure 13 , Figure 14 and Figure 15 All of the transmission mechanisms shown can be used in conjunction with the second specific implementation of the reduction differential mechanism. The resulting three gear ratios are the same as those obtained when used in conjunction with the first specific implementation of the reduction differential mechanism, which will not be elaborated here.

[0098] Furthermore, based on the calculation data from the two specific implementation methods, it can be deduced that the maximum reduction ratio achievable by the deceleration differential mechanism 40 is obtained when k3 reaches the maximum selectable value. Therefore, if a larger gear ratio is required for the 3rd gear or the highest gear, such as reaching 16, the third planetary gear set 41 can be modified to achieve this.

[0099] Figure 16 The diagram shown is a schematic of the electric drive bridge in the sixth specific embodiment. Figure 16 The deceleration differential mechanism 40 is in Figure 15 The reduction differential mechanism 40 shown is modified by altering the third planetary gear set 41. For example... Figure 16 As shown, the third planetary array 35 is a double-row single-star internal and external meshing planetary array. The structural characteristic parameters of the double-row single-star internal and external meshing planetary array can reach a maximum value of 7, and the maximum achievable deceleration ratio is calculated to be 16, k3=7, k4=15 / 8.

[0100] The double-row single-star internal and external meshing planetary gear set is kinematically a single planetary gear set, but because its planetary gears are double-linked gears, its axial length is close to that of two planetary gear sets. Due to the extremely limited axial space between the air suspension components of the axle, the placement of the fourth planetary gear set 42 is quite difficult. Therefore, the fourth planetary gear set 42 is located in the right wheel hub 621.

[0101] like Figure 16 As shown, the third gear ring 413 is fixedly connected to the fourth sun gear 421 arranged in the right wheel hub 621 via the third gear ring shaft 4131 arranged in the axle tube 11 to transmit power. The fourth gear ring 423 is fixedly connected to the axle tube 11. The right half shaft 52 is degenerated and integrated with the fourth planetary carrier 422 and the wheel hub end cap to transmit power to the right wheel hub 621 and the right wheel 62.

[0102] Figure 17 The diagram shown is a schematic of the electric drive bridge in the seventh specific embodiment. Figure 17 The deceleration differential mechanism 40 is in Figure 14 The reduction differential mechanism 40 shown is modified by altering the third planetary gear set 41. For example... Figure 17 As shown, the third planetary gear set 35 is a double-row single-planet internal and external meshing planetary gear set, and the fourth planetary gear set 42 is arranged in the right wheel hub 621. When the maximum achievable reduction ratio is 16, k3=7 and k4=15 / 7.

[0103] like Figure 17 As shown, the third gear ring 413 is fixedly connected to the fourth planetary carrier 422 arranged in the right wheel hub 621 via the third gear ring shaft 4131 arranged in the axle tube 11 to transmit power. The fourth gear ring 423 is fixedly connected to the axle tube 11. The right half shaft 52 is degenerated and integrated with the fourth sun gear 421 and the wheel hub end cap to transmit power to the right wheel hub 621 and the right wheel 62.

[0104] Obviously, Figure 7 , Figure 13 , Figure 14 and Figure 15 The transmission mechanism 30 shown can be matched with Figure 16 and Figure 17The deceleration differential mechanism 40 shown is used to obtain a larger three-gear ratio, which will not be described in detail here.

[0105] This invention provides a dual-motor, all-planetary-gear coaxial electric drive axle for heavy-duty trucks. The three-speed planetary transmission mechanism uses only four planetary gear sets and two shifting elements, resulting in a compact size, balanced mass distribution, and high adaptability. Since each motor and its associated shifting element can directly utilize the three forward gears of the transmission mechanism, it can achieve dual-motor or single-motor-three-gear drive of the vehicle. Therefore, even if one motor fails and disengages from the planetary gear set, the other motor can still drive the vehicle using the three gears of the transmission mechanism, demonstrating high fault tolerance. Furthermore, it allows for free selection of either motor to drive the vehicle when it is unloaded or partially loaded, thereby improving efficiency and ensuring that the lifespan of the two motors is essentially synchronized, thus guaranteeing the electric drive axle's B10 lifespan of millions of kilometers. During gear shifting, one motor and its associated shifting element remain in the old gear to continue driving the vehicle, while the other motor and its associated shifting element disengage and engage a new gear to participate in driving the vehicle, then remain in the old gear. The motor and its shifting elements can then shift into new gears to drive the vehicle, meaning the two motors can be engaged in different gears to drive the vehicle, thus achieving uninterrupted power shifting. The output component of the transmission mechanism is fixedly connected to the third input shaft and the input component of the reduction differential mechanism. Power can be directly transmitted to the reduction differential mechanism from the third input shaft. Thus, after setting the speed ratio achieved by the reduction differential mechanism to a 3rd gear ratio, a direct drive is realized, ensuring high transmission efficiency at high vehicle speeds. Moreover, the 1st and 2nd gear ratios only require two planetary gear sets. The number of planetary gear sets is controlled to two, and the structural characteristic parameters of the planetary gear sets are limited to about 2.2 in the existing technology, so that they and the two shifting elements can be configured in the rotor bracket cavity of the two motors, and a larger 1st gear ratio can be achieved than in the existing technology. The reduction differential mechanism uses the third and fourth planetary gear sets to achieve the 3rd gear ratio and differential function, which, together with the transmission mechanism, realizes a three-speed transmission mechanism, thus providing better overall performance.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electric drive axle for a heavy-duty truck, characterized in that, include: Bridge body; A first motor, a second motor, and a planetary transmission mechanism are mounted on the bridge body and coaxially arranged. The planetary transmission mechanism has three gears (1st, 2nd, and 3rd) and includes a transmission mechanism and a differential reduction mechanism connected to each other. The transmission mechanism has a first input shaft, a second input shaft, a third input shaft, and an output component, and includes a first planetary gear set, a second planetary gear set, a first shifting element, and a second shifting element. The third input shaft is fixedly connected to the output component and the input component of the differential reduction mechanism. The first and second shifting elements are configured to connect the first motor rotor bracket and the second motor rotor bracket to the first input shaft and the second input shaft. Simultaneous connection of one of the input shaft and the third input shaft enables dual motors to drive at the same gear. Alternatively, the first motor rotor bracket and the second motor rotor bracket can be simultaneously connected to two of the first, second, and third input shafts to enable dual motors to drive at different gears. The reduction differential mechanism achieves a reduction ratio equal to a 3-speed ratio and includes a third planetary gear set and a fourth planetary gear set connected together. One component of the third planetary gear set serves as the left output component of the reduction differential mechanism and is connected to the left wheel via the left half-shaft. One component of the fourth planetary gear set serves as the right output component of the reduction differential mechanism and is connected to the left wheel via the right half-shaft.

2. The electric drive axle for a heavy-duty truck according to claim 1, characterized in that, The first input shaft, the second input shaft, and the third input shaft are coaxially arranged in sequence. The first shifting element is a sliding sleeve inserted on the first motor rotor bracket, and when it moves axially in one direction to connect the first motor rotor bracket with the three input shafts of the transmission mechanism in sequence, it realizes gear 1, gear 2, and gear 3. The second shifting element is a sliding sleeve inserted on the second motor rotor bracket, and when it moves axially in one direction to connect the second motor rotor bracket with the three input shafts of the transmission mechanism in sequence, it realizes gear 1, gear 2, and gear 3.

3. The electric drive axle for a heavy-duty truck according to claim 2, characterized in that, The axial lengths of the first input shaft shift tooth, the second input shaft shift tooth, and the third input shaft shift tooth are all set to be greater than the sum of the axial lengths of the first shift element shift tooth and the second shift element shift tooth. The axial clearances between the first and second input shaft shift teeth and between the second and third input shaft shift teeth are all set to be greater than the axial length of either the first or second shift element shift tooth. The axial clearance on the outer side of the end of the first input shaft shift tooth away from the second input shaft shift tooth is set to be greater than the sum of the axial lengths of the first and second shift element shift teeth. The axial clearance on the outer side of the end of the third input shaft shift tooth away from the second input shaft shift tooth is set to be greater than the axial length of either the first or second shift element shift tooth.

4. The electric drive axle for a heavy-duty truck according to claim 3, characterized in that, The first planetary gear set includes a first sun gear, a first planet carrier, and a first ring gear; the second planetary gear set includes a second sun gear, a second planet carrier, and a second ring gear; both the first ring gear and the second sun gear are fixed, the first sun gear is fixedly connected to the first input shaft, the second ring gear is fixedly connected to the second input shaft, and the first planet carrier and the second planet carrier are fixedly connected as output components of the transmission mechanism.

5. The electric drive axle for a heavy-duty truck according to claim 3, characterized in that, The first planetary gear set is a single-row, double-star, internally and externally meshing planetary gear set, which includes a first sun gear, a first planet carrier, and a first ring gear; the second planetary gear set includes a second sun gear, a second planet carrier, and a second ring gear; both the first sun gear and the second sun gear are fixed, the first planet carrier is fixedly connected to the first input shaft, the second ring gear is fixedly connected to the second input shaft, and the first ring gear and the second planet carrier are fixedly connected as output components of the transmission mechanism.

6. The electric drive axle for a heavy-duty truck according to claim 3, characterized in that, The first planetary gear set includes a first sun gear, a first planet carrier, and a first ring gear; the second planetary gear set includes a second sun gear, a second planet carrier, and a second ring gear; both the first and second ring gears are fixed, the first planet carrier is fixedly connected to the second sun gear, the first sun gear is fixedly connected to the first input shaft, the second sun gear is fixedly connected to the second input shaft, and the second planet carrier serves as the output component of the transmission mechanism.

7. The electric drive axle for a heavy-duty truck according to claim 3, characterized in that, The first planetary gear set is a single-row, double-star, internally and externally meshing planetary gear set, including a first sun gear, a first planet carrier, and a first ring gear; the second planetary gear set is a single-row, double-star, internally and externally meshing planetary gear set, including a second sun gear, a second planet carrier, and a second ring gear; both the first and second planet carriers are fixed, the first ring gear is fixedly connected to the second sun gear, the first sun gear is fixedly connected to the first input shaft, the second sun gear is fixedly connected to the second input shaft, and the second ring gear serves as the output component of the transmission mechanism.

8. The electric drive axle for a heavy-duty truck according to claim 3, characterized in that, The third planetary gear set includes a third sun gear, a third planet carrier, and a third ring gear; the fourth planetary gear set is a single-row, double-star, internally and externally meshing planetary gear set, including a fourth sun gear, a fourth planet carrier, and a fourth ring gear; the third sun gear serves as the input component of the reduction differential mechanism, the third planet carrier serves as the left output component of the reduction differential mechanism and is fixedly connected to the left half-shaft, the third ring gear is fixedly connected to the fourth sun gear, the fourth ring gear remains fixed, and the fourth planet carrier serves as the right output component of the reduction differential mechanism and is fixedly connected to the right half-shaft; and the structural characteristic parameters k3 and k4 of the third and fourth planetary gear sets satisfy: k4 = 2 + 1 / k3.

9. The electric drive axle for a heavy-duty truck according to claim 3, characterized in that, The third planetary gear set includes a third sun gear, a third planet carrier, and a third ring gear; the fourth planetary gear set is a single-row, double-star, internally and externally meshing planetary gear set, including a fourth sun gear, a fourth planet carrier, and a fourth ring gear; the third sun gear serves as the input component of the reduction differential mechanism, the third planet carrier serves as the left output component of the reduction differential mechanism and is fixedly connected to the left half-shaft, the third ring gear is fixedly connected to the fourth planet carrier, the fourth ring gear remains fixed, and the fourth sun gear serves as the right output component of the reduction differential mechanism and is fixedly connected to the right half-shaft; and the structural characteristic parameters k3 and k4 of the third and fourth planetary gear sets satisfy: k4 = (1 + 2k3) / (1 + k3).

10. An electric drive axle for a heavy-duty truck according to claim 8 or 9, characterized in that, The third planetary gear set is a double-row single-star meshing planetary gear set, and the fourth planetary gear set is arranged in the right wheel hub.

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