Electric drive

Abstract

The utility model provides an electric driving device. The electric driving device comprises a first motor and a second motor, the first motor and the second motor are each provided with a planet row to transmit power to wheels, each planet row comprises an input component, an output component, a planet wheel, a first middle component and a second middle component, the input component is connected to one motor, the output component is connected to one wheel, and the planet wheel is connected to the first middle component. The two first middle components are symmetrically arranged on the left side and the right side of the rotatable bevel gear and are in meshing transmission with the bevel gear, and the two second middle components are fixedly connected. And the braking element and / or the third motor are / is used for selectively keeping the bevel gear fixed. The two first middle components are connected through the bevel gear, the two second middle components are fixedly connected, the differential function is provided during steering, the braking element and / or the third motor keep the bevel gear not rotating during straight movement, straight movement of a vehicle is ensured, and therefore the electric driving device with the excellent straight movement performance is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle transmissions and drives, and particularly to an electric drive device with dual drive motors. Background Art

[0002] Existing dual-motor electric drive devices include two drive motors on the left and right. Each drive motor independently drives a wheel through a reducer or a two-speed transmission. When going straight, even if the same torque is set for the two motors, it is still difficult to ensure that the vehicle does not deviate from the straight path. Because there are still certain differences between the actual motors, even if the same output torque is set, there is still a difference of several Newton-meters in the actual output torque. After being amplified by a reduction ratio of about 10, the difference is further increased, and the difference in drive torque on the left and right wheels will reach dozens of Newton-meters, making it impossible to ensure going straight. <>

[0003] Therefore, there is still a need to provide an electric drive device with at least better straight-line performance to solve the above problems. Summary of the Invention

[0004] In order to overcome the defects of the prior art to meet market demands, the present invention provides an electric drive device with at least better straight-line performance as follows:

[0005] The present invention provides an electric drive device, including: a first motor and a second motor; both the first motor and the second motor are equipped with a planetary gear set to transmit power to the wheels. The planetary gear set includes an input member, an output member, planet gears, a first intermediate member, and a second intermediate member. The input member is connected to the first motor or the second motor, the output member is connected to one of the wheels, the two first intermediate members are symmetrically arranged on the left and right sides of a rotatable bevel gear and are both in meshing transmission with the bevel gear, and the two second intermediate members are fixedly connected; it further includes a braking element and / or a third motor for selectively holding the bevel gear fixed.

[0006] Preferably, when going straight, the braking torque of the braking element and / or the third motor is set to be able to suppress the torque difference generated on the bevel gear through the first intermediate member due to the actually inconsistent output torques of the first motor and the second motor passing through the planetary gear sets on both sides to keep the bevel gear stationary.

[0007] Preferably, when going straight and entering a left turn, the braking element and / or the third motor is unlocked, the torque of the first motor decreases and the torque of the second motor increases. When the desired torque of the second motor is greater than the motor external characteristic, the third motor outputs torque acting on the bevel gear so that the torque of the right first intermediate member increases and the torque of the left first intermediate member decreases, thereby increasing the torque on the right output member to the desired value and decreasing the torque on the left output member to the desired value.

[0008] Preferably, when the left wheel slips, the braking element and / or the third motor are locked. The power of the first motor is transmitted from the second intermediate member to the right second intermediate member through the left planetary gear set and then to the right output member, and converges with the power transmitted by the second motor to the right output member through the right planetary gear set to drive the right wheel.

[0009] Preferably, when making a center left turn in place, the braking element and / or the third motor are unlocked. The first motor and the second motor output torques with the same magnitude and opposite directions, and drive the left and right wheels respectively after being decelerated by the left and right planetary gear sets.

[0010] Preferably, when making a fixed-point left turn, the left wheel is locked by the wheel brake. The braking element and / or the third motor are unlocked. The power transmitted by the second motor to the right output member through the right planetary gear set drives the right wheel.

[0011] Preferably, the planetary gear includes a first planetary gear and a second planetary gear fixedly connected to each other. The first planetary gear meshes with the first sun gear, the second planetary gear meshes with the ring gear, the second planetary gear meshes with the second sun gear, and the ring gear is also provided with a bevel tooth meshing and driving with a bevel gear. Wherein, the first sun gear serves as the input member, the output member is the planet carrier, the ring gear serves as the first intermediate member, and the second sun gear serves as the second intermediate member.

[0012] Preferably, the planetary gear includes a first planetary gear and a second planetary gear fixedly connected to each other. The first planetary gear meshes with both the sun gear and the first ring gear, the second planetary gear meshes with the second ring gear, and the first ring gear is also provided with a bevel tooth meshing and driving with a bevel gear. Wherein, the sun gear serves as the input member, the second ring gear serves as the output member, the first ring gear serves as the first intermediate member, and the second intermediate member is the planet carrier.

[0013] In the electric drive device of the present invention, both motors are equipped with planetary gear sets. The two first intermediate members are symmetrically arranged on the left and right sides of the rotatable bevel gear and both mesh with the bevel gear for driving. The two second intermediate members are fixedly connected to provide a differential function during the steering process. A braking element and / or a third motor are also provided to selectively fix the bevel gear. When going straight, the braking torque of the braking element and / or the third motor is set to suppress the torque difference generated on the bevel gear due to the actually inconsistent output torques of the first motor and the second motor acting on the bevel gear through the planetary gear set, and keep the bevel gear stationary. Therefore, the straight running of the vehicle is ensured, and thus an electric drive device with at least better straight running performance is obtained. Description of the Drawings

[0014] One or more embodiments are exemplarily illustrated by corresponding drawings. These exemplary illustrations and drawings do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are shown as similar elements. The drawings do not constitute a scale limitation, and wherein:

[0015] Figure 1 Shown is a transmission schematic diagram of an electric drive device according to a first specific embodiment;

[0016] Figure 2 Shown is a transmission schematic diagram of an electric drive device according to a second specific embodiment.

[0017] Symbol description: 11, first motor; 12, second motor; 13, third motor; 20, planetary gear set; 21, input member; 22, output member; 23, planetary gear; 24, first intermediate member; 25, second intermediate member; 231, first planetary gear; 232, second planetary gear; 26, bevel gear; 27, braking element; 30, wheel. Detailed implementation manners

[0018] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. Embodiment 1:

[0019] Figure 1 Shown is a transmission schematic diagram of an electric drive device according to a first specific embodiment. As Figure 1 shown, an electric drive device includes: a first motor 11 and a second motor 12; both the first motor 11 and the second motor 12 are equipped with a planetary gear set 20 to transmit power to the wheel 30. The planetary gear set 20 includes an input member 21, an output member 22, a planetary gear 23, a first intermediate member 24, and a second intermediate member 25. The input member 21 is connected to one of the first motor 11 or the second motor 12, the output member 22 is connected to one of the wheels 30, the two first intermediate members 24 are symmetrically arranged on the left and right sides of the rotatable bevel gear 26 and are both meshed with the bevel gear 26 for transmission, and the two second intermediate members 25 are fixedly connected; further includes a braking element 27 and / or a third motor 13 for selectively holding the bevel gear 26 fixed.

[0020] It should be noted that locking or latching herein refers to operating a member to apply a force to another member so that the member is fixed or stationary and does not rotate, while unlocking refers to operating a member so that the force acting on another member disappears so that the member can rotate.

[0021] In addition, for clearer description, in the specific working conditions involved below, the left and right sides shown in the figure are used to indicate components such as the planetary gear set or the wheels. And the state of the left side or towards the left is mostly used as a reference for description, which does not affect the specific content, and the state of the right side or towards the right can also be analogized without doubt.

[0022] Specifically, when going straight, the braking torque of the braking element 27 and / or the third motor 13 is set to suppress the torque difference generated on the bevel gear 26 by the actual inconsistent output torques of the first motor 11 and the second motor 12 acting on the bevel gear 26 through the first intermediate member 24 when passing through the two-side planetary gear set 20, so as to keep the bevel gear 26 stationary. When the bevel gear 26 is stationary and the two second intermediate members 25 are fixedly connected, the rotational speeds of the two output members 22 are thus the same, and the influence of the actual inconsistent output torques of the first motor 11 and the second motor 12 on going straight is eliminated.

[0023] If the actual torque difference generated by the two first motors 11 and the second motor 12 is 5 Nm, assuming that the transmission ratio between the bevel gear 26 and the bevel teeth on the first intermediate member 24 meshing with it is 1 / (2k) of the structural characteristic parameter k of the planetary gear set 20, then the driving torque generated on the bevel gear 26 is 10 Nm, and the braking element 27 and / or the third motor 13 should generate a braking torque slightly greater than 10 Nm to keep the bevel gear 26 fixed and non-rotating.

[0024] When steering, the braking element 27 and / or the third motor 13 is unlocked and the bevel gear 26 rotates. When steering, the rotational speeds of the two-side wheels 30 are different, the rotational speeds of the two output members 22 are not the same, the bevel gear 26 functions as a differential, the rotational speeds of the two first intermediate members 24 are the same but in opposite directions, and the rotational speeds of the two second intermediate members 25 are the same. The braking element 27 and / or the third motor 13 is associated with the steering wheel angle. When the steering wheel angle is greater than a certain threshold, no appropriate braking torque will be generated to keep the bevel gear 26 stationary. After entering the steering process, the braking element 27 and / or the third motor 13 is unlocked, and the braking torque rapidly decreases to zero, and the bevel gear 26 can rotate to avoid adverse effects on steering.

[0025] The third motor 13 can not only generate a braking or locking torque acting on the bevel gear 26, but it can also act as a torque vector motor, outputting torque to adjust the driving torques on the two-side wheels 30 to obtain better lateral dynamic characteristics. In the scheme of independently driving the wheels by two motors, the torque vector function is achieved by adjusting the output torques of the two motors. However, when the desired torque of the outer motor exceeds the external characteristics of this motor, the required function cannot be achieved. By means of the third motor 13 to provide a greater torque, the torque vector function can be further expanded.

[0026] Specifically, when going straight and turning left, the braking element 27 and / or the third motor 13 are unlocked, the torque of the first motor 11 decreases and the torque of the second motor 12 increases. When the desired torque of the second motor 12 is greater than the external characteristic of the motor, the third motor 13 outputs torque to act on the bevel gear 26, so that the torque of the right first intermediate member 24 increases and the torque of the left first intermediate member 24 decreases, thereby increasing the torque on the right output member 22 to the desired value and decreasing the torque on the left output member 22 to the desired value.

[0027] That is, during steering, torque vector control is performed on the first motor 11 and the second motor 12. The output torque of the outer motor increases and the output torque of the inner motor decreases. Usually, the torque increment values on both sides are equal in magnitude and opposite in direction. If the value of the desired torque is greater than the external characteristic of the motor, then if the third motor 13 is configured, the third motor 13 is used to further expand the drive torque difference on the two side wheels 30 and enhance the torque vector function.

[0028] Specifically, when turning left around the center in place, the braking element 27 and / or the third motor 13 are unlocked, and the first motor 11 and the second motor 12 output torques that are equal in magnitude and opposite in direction. After being decelerated by the planetary gear set 20, they are output to drive the two side wheels 30 respectively, so that the vehicle turns left around its center in place. There are certain differences in the road resistance on different road surfaces, and different steering speeds also require different drive torques. The output torques of the first motor 11 and the second motor 12 can be set according to specific conditions to meet the power requirements.

[0029] Specifically, when turning left at a fixed point, the left wheel 30 is braked and locked by the vehicle braking system. The braking element 27 and / or the third motor 13 are unlocked. The power transmitted by the second motor 12 to the right output member 22 through the planetary gear set 20 drives the right wheel 30, so that the vehicle turns left around one of its wheels at a fixed point. Turning at a fixed point means that a four-wheel vehicle can rotate around a certain wheel, and this wheel is locked by the wheel brake. The outer first motor 11 or the second motor 12 drives the outer wheel 30 to move forward or backward, so as to achieve turning left or right at a fixed point.

[0030] Specifically, when the left wheel 30 slips, the braking element 27 and / or the third motor 13 are locked. The power of the first motor 11 is transmitted from the second intermediate member 25 on the left through the left planetary gear set 20 to the second intermediate member 25 on the right, and then transmitted to the right output member 22. After converging with the power transmitted by the second motor 12 to the right output member 22 through the right planetary gear set 20, it drives the right wheel 30.

[0031] The second intermediate member 25 provided in the planetary gear set 20 and the two second intermediate members 25 are fixedly connected, which not only ensures the straight running performance, but also constructs a transmission branch between the two planetary gear sets 20, so as to transmit the power of the first motor 11 or the second motor 12 on one side to the planetary gear set 20 on the other side, realizing the function of transmitting all the power to the non-slip side wheels 30 when there is a differential lock.

[0032] As Figure 1 shown, a specific solution of the planetary gear set 20 is: the planetary gear 23 includes a first planetary gear 231 and a second planetary gear 232 fixedly connected to each other. The first planetary gear 231 meshes with the first sun gear, the second planetary gear 232 meshes with the ring gear, and the ring gear is also provided with a bevel gear meshing and driving with the bevel gear 26. The second sun gear meshes with the second planetary gear 232. Among them, the first sun gear serves as the input member 21, the output member 22 is the planet carrier, the ring gear serves as the first intermediate member 24, and the second sun gear serves as the second intermediate member 25.

[0033] The reduction ratio that the planetary gear set 20 can achieve can be calculated according to Equation (1):

[0034] ;

[0035] In the formula, Zs1, Zp1, Zr, and Zp2 are the number of teeth of the first sun gear, the first planetary gear 231, the ring gear, and the second planetary gear 232 respectively. A tooth matching solution is: Zs1 = 27, Zp1 = 44, Zr = 89, and Zp2 = 16. According to Equation (1), i = 10.1 can be obtained.

[0036] The reduction ratio that the planetary gear set 20 can achieve can be calculated according to Equation (1), which will not be elaborated here. For Figure 1 the solution, when going straight, turning, and locking against slipping, the planetary gear set 20 can achieve the corresponding reduction ratio.

[0037] When making a central turn in place, the bevel gear 26 can rotate, the rotational speed of the second sun gear is 0, and the reduction ratio of the planetary gear set 20 is calculated according to Equation (2):

[0038] ;

[0039] In the formula, Zs2 is the number of teeth of the second sun gear, and Zs2 = 55 is obtained by tooth matching. According to Equation (2), i = -4.6 can be obtained. This means that the two first motors 11 and the second motor 12 not only rotate in opposite directions, but also rotate in opposite directions to the rotational speed of the wheels on the same side, so that the same central turn in place to the right or left can be achieved.

[0040] In addition, other tooth matching solutions can also be adopted to further increase the value of the reduction ratio obtained by Equation (2) on the premise of ensuring that the reduction ratio obtained by Equation (1) reaches the expected value.

[0041] For fixed-point steering, the rotational speed relationship between the outer motor and the inner motor can be obtained as shown in the following formula (3):

[0042] ;

[0043] In the formula, n2 is the rotational speed of the outer motor, and n1 is the rotational speed of the inner motor. According to the gear ratio, n2 = 0.3725n1 can be obtained, that is, the rotational speed directions of the inner and outer motors are the same. Through the analysis of the torque direction, it can be known that the torque of the inner motor is negative. Therefore, the inner motor absorbs part of the power during the fixed-point steering process so that the outer motor can drive the outer wheels. Embodiment 2:

[0044] Figure 2 The transmission schematic diagram of the electric drive device of the second specific embodiment is shown as follows. As Figure 2 shown, another specific solution for the planetary gear set 20 is: the planetary gear 23 includes a first planetary gear 231 and a second planetary gear 232 that are fixedly connected to each other. The first planetary gear 231 meshes with the sun gear and the first ring gear simultaneously, the second planetary gear 232 meshes with the second ring gear, and a bevel gear meshing with the bevel gear 26 is also provided on the first ring gear. Among them, the sun gear serves as the input member 21, the second ring gear serves as the output member 22, the first ring gear serves as the first intermediate member 24, and the second intermediate member 25 is the planetary carrier.

[0045] The reduction ratio that the planetary gear set 20 can achieve can be calculated according to formula (4):

[0046] ;

[0047] In the formula, Zs, Zr1, Zp1, Zp2, and Zr2 are the number of teeth of the sun gear, the first ring gear, the first planetary gear, the second planetary gear, and the second ring gear respectively. A gear ratio solution is: Zs = 16, Zp1 = 32, Zr1 = 80, Zp2 = 16, and Zr2 = 64. According to formula (4), i = 16 can be obtained.

[0048] For the Figure 2 solution, during straight running, steering, and slip locking, the planetary gear set 20 can achieve the corresponding reduction ratio.

[0049] During in-situ center steering, the bevel gear 26 can rotate, the rotational speed of the planetary carrier is 0, and the reduction ratio of the planetary gear set 20 is calculated according to formula (5):

[0050] ;

[0051] According to formula (5), i = -8 can be obtained. Other gear ratio solutions can also be adopted to further increase the value of the reduction ratio obtained by formula (5) on the premise of ensuring that the reduction ratio obtained by formula (4) reaches the expected value.

[0052] For fixed-point steering, the rotational speed relationship between the outer motor and the inner motor can be obtained as shown in the following equation (6):

[0053]

[0054] In the formula, n2 is the rotational speed of the outer motor, and n1 is the rotational speed of the inner motor. According to the gear ratio, n2 = 0.3333n1 can be obtained, that is, the rotational speed directions of the inner and outer motors are the same. Through the analysis of the torque direction, it can be known that the torque of the inner motor is negative. Therefore, the inner motor absorbs part of the power during fixed-point steering so that the outer motor can drive the outer wheels.

[0055] The braking element 27 can be a single-piece or multi-piece brake of electromechanical, electromagnetic, pneumatic or electro-hydraulic type, and can be selected according to specific circumstances. By using a disc brake, when encountering a slippery road surface during driving, the function of the differential lock can be realized without stopping, while a common differential lock usually requires stopping to engage the lock and then driving again.

[0056] The first motor 11 and the second motor 12 are preferably permanent magnet motors with high efficiency. The third motor 13 is preferably a switched reluctance motor suitable for its operating conditions.

[0057] The electric drive device can be used as the rear axle or the front axle, and can be selected according to specific circumstances.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electric drive device, characterized in that, Including: A first motor (11) and a second motor (12); both the first motor (11) and the second motor (12) are equipped with a planetary gear set (20) to transmit power to the wheels (30). The planetary gear set (20) includes an input member (21), an output member (22), planetary gears (23), a first intermediate member (24), and a second intermediate member (25). The input member (21) is connected to the first motor (11) or the second motor (12), the output member (22) is connected to one of the wheels (30), two of the first intermediate members (24) are symmetrically arranged on the left and right sides of a rotatable bevel gear (26) and are both in meshing transmission with the bevel gear (26), and two of the second intermediate members (25) are fixedly connected; further including a braking element (27) and / or a third motor (13) for selectively holding the bevel gear (26) fixed.

2. The electric drive device according to claim 1, characterized in that When going straight, the braking torque of the braking element (27) and / or the third motor (13) is set to suppress the torque difference generated on the bevel gear (26) through the first intermediate member (24) when the actually inconsistent output torques of the first motor (11) and the second motor (12) pass through the planetary gear sets (20) on both sides, so as to keep the bevel gear (26) from rotating.

3. The electric drive device according to claim 1, characterized in that, When going straight and entering a left turn, the braking element (27) and / or the third motor (13) is unlocked, the torque of the first motor (11) decreases and the torque of the second motor (12) increases. When the desired torque of the second motor (12) is greater than the external characteristic of the motor, the third motor (13) outputs torque to act on the bevel gear (26) so that the torque of the right first intermediate member (24) increases and the torque of the left first intermediate member (24) decreases, thereby increasing the torque on the right output member (22) to the desired value and decreasing the torque on the left output member (22) to the desired value.

4. The electric drive device according to claim 1, characterized in that, When the left wheel (30) slips, the braking element (27) and / or the third motor (13) is locked, and the power of the first motor (11) is transmitted from the second intermediate member (25) of the left planetary gear set (20) to the right second intermediate member (25) and then to the right output member (22), and is confluent with the power transmitted from the second motor (12) through the right planetary gear set (20) to the right output member (22) to drive the right wheel (30).

5. The electric drive device according to claim 1, characterized in that When making a center left turn in place, the braking element (27) and / or the third motor (13) is unlocked, and the first motor (11) and the second motor (12) output torques of the same magnitude and opposite directions, which are respectively decelerated by the left and right planetary gear sets (20) to drive the left and right wheels (30).

6. The electric drive device according to claim 1, characterized in that, When making a fixed-point left turn, the left wheel (30) is locked by the wheel (30) brake, the braking element (27) and / or the third motor (13) is unlocked, and the power transmitted from the second motor (12) through the right planetary gear set (20) to the right output member (22) drives the right wheel (30).

7. The electric drive device according to any one of claims 1 to 6, characterized in that The planetary gear (23) includes a first planetary gear (231) and a second planetary gear (232) fixedly connected to each other. The first planetary gear (231) meshes with the first sun gear, the second planetary gear (232) meshes with the ring gear, the second planetary gear (232) meshes with the second sun gear, and the ring gear is further provided with a bevel gear meshing and driving with the bevel gear (26). Wherein, the first sun gear serves as the input member (21), the output member (22) is the planet carrier, the ring gear serves as the first intermediate member (24), and the second sun gear serves as the second intermediate member (25).

8. The electric drive device according to any one of claims 1 to 6, characterized in that The planetary gear (23) includes a first planetary gear (231) and a second planetary gear (232) fixedly connected to each other. The first planetary gear (231) meshes with the sun gear and the first ring gear simultaneously, the second planetary gear (232) meshes with the second ring gear, and the first ring gear is further provided with a bevel gear meshing and driving with the bevel gear (26). Wherein, the sun gear serves as the input member (21), the second ring gear serves as the output member (22), the first ring gear serves as the first intermediate member (24), and the second intermediate member (25) is the planet carrier.

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