Dual electric drive axle system and vehicle

Abstract

A dual electric drive axle system, comprising a first drive electric motor (M1), a second drive electric motor (M2), a differential (7), a first gear reduction unit, a second gear reduction unit and an electric motor controller, wherein the first drive electric motor (M1) is in transmission connection with the differential (7) by means of the first gear reduction unit, and the second drive electric motor (M2) is in transmission connection with the differential (7) by means of the second gear reduction unit; the transmission ratio of the first gear reduction unit is smaller than that of the second gear reduction unit; the first drive electric motor (M1) and the second drive electric motor (M2) are electrically connected to the electric motor controller; and the first drive electric motor (M1) is a synchronous electric motor, and the second drive electric motor (M2) is an asynchronous electric motor. A vehicle, being provided with one or more rear axles and provided with the dual electric drive axle system. In this way, when the first drive electric motor operates independently, a rotor of the second drive electric motor idles without generating back electromotive force and cogging torque, so that energy loss is avoided, and there is no need to provide a disconnection mechanism, thereby improving the reliability of a product and reducing the risk of failure.

Description

Dual electric drive axle system and vehicle TECHNICAL FIELD

[0001] The present application belongs to the technical field of vehicles, and particularly relates to a dual electric drive axle system and vehicle. BACKGROUND

[0002] New energy commercial vehicles include various types, each type needs to correspond to different working conditions, and therefore, the driving system needs to have multi-working condition adaptability. For example, highway buses need to meet mountain climbing working conditions and urban commuting and inter-city high-speed operation working conditions; heavy trucks need to ensure sufficient power in high-speed full-load cargo transport working conditions and relatively low energy consumption in high-speed light-load return working conditions. Existing driving systems are usually divided into two driving forms. One is a direct drive system, which is driven by a central direct drive motor to drive a transmission shaft, and the transmission shaft drives a rear axle. The other is an AMT (Automated-Mechanical-Transmission) variable speed system, which is driven by a driving motor through an AMT variable speed box to drive a transmission shaft, and the transmission shaft drives a rear axle.

[0003] For the direct drive system, the high efficiency area of the central direct drive motor can be designed in the high-speed low-torque area to meet the inter-city high-speed operation working condition of the vehicle, or in the low-speed high-torque area to meet the mountain climbing working condition, but it cannot simultaneously consider the high-speed low-torque area and the low-speed high-torque area, and has poor multi-working condition adaptability, low driving efficiency and high driving system energy consumption. The AMT variable speed system has complex structure, low transmission efficiency, and problems of gear shifting smoothness and product reliability.

[0004] Chinese patent application with publication number CN116691331A discloses a dual electric drive axle system and vehicle. The system controls the switching of the front electric drive module and the front axle differential module between the transmission connection working condition and the disconnection working condition through the configuration of a disconnection mechanism, so as to realize the switching of low-speed high-torque and high-speed working conditions. The disadvantages are that in the disconnection working condition, the disconnected motor idling generates back electromotive force and cogging torque, resulting in energy loss; secondly, the disconnection mechanism also reduces the reliability of the product and increases the failure risk. SUMMARY

[0005] The present application aims to provide a dual electric drive axle system and control method, and vehicle, to solve the problems that the existing dual electric drive system in the disconnection working condition, the disconnected motor idling generates back electromotive force and cogging torque, resulting in energy loss; secondly, the disconnection mechanism also reduces the reliability of the product and increases the failure risk.

[0006] The application is to solve the above technical problems by the following technical scheme: a double electric drive axle system, comprising a first driving motor, a second driving motor, a differential, a first gear reduction unit, a second gear reduction unit and a motor controller; the first driving motor is in transmission connection with the differential through the first gear reduction unit, and the second driving motor is in transmission connection with the differential through the second gear reduction unit.

[0007] The transmission ratio of the first gear reduction unit is smaller than that of the second gear reduction unit; the first driving motor and the second driving motor are respectively in electrical connection with the motor controller; wherein the first driving motor is a synchronous motor, and the second driving motor is an asynchronous motor.

[0008] Compared with the prior art double synchronous motor double electric drive axle system, the application adopts the technical scheme that the first driving motor is a synchronous motor and the second driving motor is an asynchronous motor, so that when the first driving motor works alone and the second driving motor rotor idles, no counter electromotive force and slot torque are generated, and no energy loss is caused. In addition, there is no need to be equipped with a disconnecting mechanism, thereby improving the reliability of the product and reducing the failure risk. Further, the first driving motor is a flat wire permanent magnet synchronous motor, and the second driving motor is a flat wire induction asynchronous motor.

[0009] Further, the first driving motor and the second driving motor are symmetrically arranged about the center of the differential.

[0010] Further, the first gear reduction unit is composed of a first gear and a second gear, the first gear is coaxial with the first driving motor, the first gear is in meshing engagement with the second gear, and the rotating shaft of the second gear is connected with the differential; the second gear reduction unit is composed of a third gear, a fourth gear, a fifth gear and a sixth gear, the sixth gear is coaxial with the second driving motor, the sixth gear is in meshing engagement with the fifth gear, the fifth gear is coaxial with the fourth gear, the fourth gear is in meshing engagement with the third gear, and the third gear is in meshing engagement with the second gear.

[0011] Further, the first driving motor, the second driving motor, the differential, the first gear reduction unit and the second gear reduction unit are integrated in the axle housing of the driving rear axle.

[0012] Based on the same concept, the application provides a vehicle, which has only one rear axle, and the rear axle is provided with the double electric drive axle system as described above; the vehicle has multiple rear axles, and at least two of the rear axles are respectively provided with the double electric drive axle system as described above. Advantages

[0013] Compared with the prior art, the application has the following advantages:

[0014] The technical scheme of the application adopts the technical scheme that the first driving motor is a synchronous motor and the second driving motor is an asynchronous motor, so that when the first driving motor works alone, the second driving motor rotor idles, no counter electromotive force and slot torque are generated, and no energy loss is caused. In addition, no disconnection mechanism is needed, thereby improving the reliability of the product and reducing the failure risk.

[0015] The output shaft of the first driving motor is integrated with the input shaft of the first gear reduction unit, and the output shaft of the second driving motor is integrated with the input shaft of the second gear reduction unit, thereby improving the transmission accuracy, improving the structural strength of the system, and reducing the weight and volume of the system.

[0016] The first driving motor and the second driving motor correspond to different transmission ratios, so that the working points of the first driving motor and the second driving motor are distributed in the high-efficiency zone. By controlling the first driving motor to work alone, the second driving motor to work alone, or the first driving motor and the second driving motor to work together, different working conditions can be adapted, the system can continuously work in the high-efficiency zone, the multi-working-condition adaptability and driving efficiency of the system are improved, the performance of the system is effectively improved, and the energy consumption of the whole vehicle is reduced.

[0017] By selecting a single double-electric-drive bridge system or multiple double-electric-drive bridge systems, different driving working conditions of different vehicle models can be adapted, and the power performance and economic performance of the system are ensured. The application does not have a gear shifting mechanism, reduces the mechanical structure, reduces the structural complexity, and improves the comfort and reliability of the vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical scheme of the application, the drawings needed in the following embodiment description will be briefly introduced. Obviously, the drawings in the following description are only one embodiment of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0019] Fig. 1 is a structural schematic diagram of a single double-electric-drive bridge system in an embodiment of the application;

[0020] Fig. 2 is a topology diagram of a single double-electric-drive bridge system in an embodiment of the application;

[0021] Fig. 3 is a first driving motor alone driving mechanical transmission diagram of a single double-electric-drive bridge system in an embodiment of the application;

[0022] Fig. 4 is a high-efficiency working zone diagram of a first driving motor in an embodiment of the application; wherein, the horizontal coordinate n represents the speed, and the vertical coordinate T represents the torque;

[0023] Fig. 5 is a second driving motor alone driving mechanical transmission diagram of a single double-electric-drive bridge system in an embodiment of the application;

[0024] Fig. 6 is a high-efficiency working interval diagram of the second driving motor in the embodiment of the present application; wherein the horizontal axis n represents the rotating speed, and the vertical axis T represents the torque;

[0025] Fig. 7 is a mechanical transmission diagram of the first driving motor and the second driving motor jointly driving in the single double-electric-drive-axle system in the embodiment of the present application;

[0026] Fig. 8 is a structural diagram of the two double-electric-drive-axle systems in the embodiment of the present application;

[0027] Fig. 9 is a topological diagram of the two double-electric-drive-axle systems in the embodiment of the present application;

[0028] Fig. 10 is a mechanical transmission diagram of the first driving motor separately driving in the two double-electric-drive-axle systems in the embodiment of the present application;

[0029] Fig. 11 is a mechanical transmission diagram of the second driving motor separately driving in the two double-electric-drive-axle systems in the embodiment of the present application;

[0030] Fig. 12 is a mechanical transmission diagram of the first driving motor and the second driving motor jointly driving in the two double-electric-drive-axle systems in the embodiment of the present application.

[0031] Legend: 1 - first gear, 2 - second gear, 3 - third gear, 4 - fourth gear, 5 - fifth gear, 6 - sixth gear, 7 - differential. DETAILED DESCRIPTION

[0032] The technical solutions in the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0033] The technical solutions of the present application will be described in detail below in combination with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes can not be described in some embodiments.

[0034] As shown in FIG. 1 and FIG. 2, the double electric drive axle system provided by the embodiment of the application comprises a first drive motor M1, a second drive motor M2, a differential 7, a first gear reduction unit, a second gear reduction unit and a motor controller; the first gear reduction unit is composed of a first gear 1 and a second gear 2, the first gear 1 is coaxial with the first drive motor M1, the first gear 1 is engaged with the second gear 2, and the rotating shaft of the second gear 2 is connected with the differential 7; the second gear reduction unit is composed of a third gear 3, a fourth gear 4, a fifth gear 5 and a sixth gear 6, the sixth gear 6 is coaxial with the second drive motor M2, the sixth gear 6 is engaged with the fifth gear 5, the fifth gear 5 is coaxial with the fourth gear 4, the fourth gear 4 is engaged with the third gear 3, and the third gear 3 is engaged with the second gear 2; the transmission ratio i1 of the first gear reduction unit is smaller than the transmission ratio i2 of the second gear reduction unit; the first drive motor M1, the second drive motor M2 and the motor controller are electrically connected.

[0035] The rotating shaft of the first gear 1 is the same shaft as the output shaft of the first drive motor M1, the rotating shaft of the sixth gear 6 is the same shaft as the output shaft of the second drive motor M2, and the rotating shaft of the fifth gear 5 is the same shaft as the rotating shaft of the fourth gear 4, which improves the transmission accuracy and structural strength, and reduces the structural complexity, weight and volume of the system. The first drive motor M1 corresponds to the first gear reduction unit, the second drive motor M2 corresponds to the second gear reduction unit, the transmission ratio i1 of the first gear reduction unit is smaller than the transmission ratio i2 of the second gear reduction unit, which can make the working condition points of the first drive motor M1 and the second drive motor M2 be distributed in the high-efficiency area, thereby improving the driving efficiency of the system. The second gear reduction unit is composed of four gears, and under the same transmission ratio, compared with the reduction unit composed of two gears, the reduction unit composed of four gears can reduce the size of the gears.

[0036] In the specific embodiment of the application, the first drive motor M1 is a flat wire permanent magnet synchronous motor, and the second drive motor M2 is a flat wire induction asynchronous motor. Compared with a round wire motor, the flat wire motor has higher power density and driving efficiency (smaller end loss); under the same performance, the flat wire motor has smaller weight and volume; and the flat wire motor can improve the NVH (Noise, Vibration and Harshness) performance of the gear reduction unit. If the second drive motor M2 is a permanent magnet synchronous motor, when the first drive motor M1 works alone, the rotor of the second drive motor M2 idles to generate back electromotive force and cogging torque, causing energy loss. The second drive motor M2 selects a flat wire induction asynchronous motor to solve the problem.

[0037] In the specific embodiment of the application, the first drive motor M1 and the second drive motor M2 are symmetrically arranged about the center of the differential 7, which eliminates the influence of accessory torque on the axle and suspension.

[0038] In the specific embodiment of the application, the first driving motor M1, the second driving motor M2, the differential 7, the first gear reduction unit and the second gear reduction unit are integrated in the axle housing of the driving rear axle. The two driving motors, the differential 7, the two reduction units and the axle housing are an integral structure, which improves the strength of the transmission structure and reduces the weight and volume of the entire system.

[0039] The double electric drive axle system is applied to a vehicle, and a single double electric drive axle system is arranged on the rear axle of the vehicle.

[0040] (1) The first driving motor M1 of the single double electric drive axle system works alone.

[0041] When the vehicle is running at high speed (for example, the running speed of the vehicle is greater than or equal to 80 km / h) or at low speed (for example, the running speed of the vehicle is less than or equal to 40 km / h), the first driving motor M1 is controlled to work alone, and the driving efficiency of the first driving motor M1 is greater than 90%, as shown in FIG. 3.

[0042] The first driving motor M1 is a flat wire permanent magnet synchronous motor, which has the advantages of high power factor and high efficiency. The transmission of the first gear reduction unit corresponding to the first driving motor M1 is small, so that the working interval of the first driving motor M1 is distributed in the low torque area, that is, the driving efficiency of the working interval of the first driving motor M1 is greater than 90% (high efficiency area), wherein the driving efficiency of the motor refers to the proportion of the conversion of electrical energy into mechanical energy by the motor. For example, the power and torque of the two motors can be distributed by VCU, so that the two motors work in the high efficiency interval. When the first driving motor M1 works alone, it is equivalent to the overspeed / high speed gear of the traditional fuel vehicle, which meets the high speed stable working condition demand of the vehicle, and also meets the low speed, low speed acceleration and low speed climbing demand of the vehicle. At this time, the first driving motor M1 works in the high efficiency working interval, as shown in FIG. 4, the high efficiency working interval of the first driving motor M1 is distributed in the low torque area, and the transmission of the first gear reduction unit corresponding to the first driving motor M1 is small, which reduces the energy loss.

[0043] When the first driving motor M1 works, it will drive the rotor of the second driving motor M2 to rotate. If the second driving motor M2 is a permanent magnet synchronous motor, a counter electromotive force will be generated inside it, and the cogging torque of the permanent magnet will cause energy loss and reduce the driving efficiency. Therefore, the second driving motor M2 of the application is a flat wire induction asynchronous motor. When the first driving motor M1 drives the rotor of the second driving motor M2 to rotate, the stator of the second driving motor M2 is not excited, and no counter electromotive force and additional energy loss are generated.

[0044] In an embodiment, the first speed threshold is 80 km / h and the second speed threshold is 40 km / h.

[0045] (2) The second driving motor M2 of the single dual electric drive axle system works alone.

[0046] When the vehicle is in a climbing working condition (for example, 0 < climbing degree ≤ 25%), the second driving motor M2 is controlled to work alone and the driving efficiency of the second driving motor M2 is greater than 90%, as shown in FIG. 5.

[0047] The second driving motor M2 is selected to be a flat wire induction asynchronous motor, which has the advantages of high speed and high efficiency. The transmission of the second gear reduction unit corresponding to the second driving motor M2 is relatively large, so that the working interval of the second driving motor M2 is distributed in the high-speed low-torque zone, that is, the driving efficiency of the working interval of the second driving motor M2 is greater than 90% (high efficiency zone). When the second driving motor M2 works alone, it is equivalent to the medium and low speed gears of the traditional fuel vehicle, which meets the low-speed climbing working condition requirement of the vehicle. At this time, the second driving motor M2 works in the high efficiency working interval, as shown in FIG. 6, the high efficiency working interval of the second driving motor M2 is distributed in the low torque zone, and the transmission of the second gear reduction unit corresponding to the second driving motor M2 is relatively large, which can reduce energy loss.

[0048] (3) The first driving motor M1 and the second driving motor M2 of the single dual electric drive axle system work together.

[0049] When the first driving motor M1 and the second driving motor M2 work together, the maximum power output is equivalent to one gear of the traditional fuel vehicle, which can meet the starting acceleration and extreme climbing working condition requirements of the vehicle, and can also meet the low-speed acceleration and high-speed overtaking working condition requirements of the vehicle, as shown in FIG. 7. Specifically as follows:

[0050] a. When the vehicle starts, the first driving motor M1 and the second driving motor M2 start together to provide sufficient starting torque and acceleration torque;

[0051] b. When the vehicle is running at low speed or high speed (at this time, the first driving motor M1 works), the second driving motor M2 quickly responds to meet the power requirement of the vehicle when encountering sudden acceleration (for example, overtaking) or extreme climbing working condition.

[0052] Compared with the asynchronous motor, the permanent magnet synchronous motor has higher efficiency, so the vehicle is in the braking and coasting condition, and the first drive motor M1 is used for braking energy recovery. Because the braking torque of a single motor is small, in the emergency braking or long downhill condition, the first drive motor M1 and the second drive motor M2 simultaneously perform electric braking, which improves the braking efficiency of the vehicle, shortens the braking distance, and improves the braking energy recovery rate. Long downhill refers to a road section with a longitudinal slope greater than or equal to 3% and a continuous slope length exceeding a limit value (generally 2 kilometers).

[0053] For heavy trucks with heavy loads, two double electric drive axle systems can be selected. The heavy truck has multiple rear axles, and the two double electric drive axle systems are arranged on the two rear axles of the vehicle, as shown in FIGS. 8 and 9. The control method of the two double electric drive axle systems includes:

[0054] (1) The first drive motor of the two double electric drive axle systems works alone, that is, the two first drive motors M1, M3 work.

[0055] When the vehicle is in an empty or light load high speed condition (for example, the loaded mass of the vehicle is less than 1 / 2 of the maximum loaded mass and the driving speed of the vehicle is greater than or equal to 80 km / h), or in an overtaking condition, the first drive motors M1, M3 of the two double electric drive axle systems are controlled to work, as shown in FIG. 10.

[0056] In the unloading return stage of the heavy truck, the two first drive motors M1, M3 of the two double electric drive axle systems work, reducing tire wear.

[0057] (2) The second drive motor of the two double electric drive axle systems works alone, that is, the two second drive motors M2, M4 work.

[0058] As shown in FIG. 11, when the vehicle is in a half load low speed climbing condition, the second drive motors M2, M4 of the two double electric drive axle systems are controlled to work; when the vehicle is in a full load low speed condition, the second drive motors M2, M4 of the two double electric drive axle systems are controlled to work.

[0059] The two second drive motors M2, M4 are matched with two second gear reduction units with large transmission ratios, which provide sufficient power in low speed conditions and improve driving efficiency.

[0060] (3) The first drive motor and the second drive motor of the two double electric drive axle systems work together, that is, the two first drive motors M1, M3 and the two second drive motors M2, M4 work.

[0061] As shown in FIG. 12, when the vehicle is in the extreme climbing working condition (for example, 25% < climbing degree), the first driving motor M1, M3 and the second driving motor M2, M4 of the two double electric drive axle systems are controlled to work together; when the vehicle is in the high-speed full-load working condition (for example, the driving speed of the vehicle ≥ 80 km / h), the first driving motor M1, M3 and the second driving motor M2, M4 of the two double electric drive axle systems are controlled to work together; when the vehicle is in the heavy-load overtaking working condition (for example, 1 / 2 < the loaded mass of the vehicle < the maximum loaded mass), the first driving motor M1, M3 and the second driving motor M2, M4 of the two double electric drive axle systems are controlled to work together, and sufficient power is provided for the vehicle in various extreme working conditions.

[0062] The power requirements of various working conditions are different, and the various working conditions can be judged according to the power requirements, and the driving mode is controlled to adapt to various different working conditions, so as to ensure that the double electric drive axle system can operate at the best efficiency point in each working condition, reduce the energy consumption of the system, and improve the driving range of the vehicle.

[0063] The above only discloses specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or modifications within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A dual electric drive axle system, characterized in that, The system comprises a first driving motor, a second driving motor, a differential, a first gear reduction unit, a second gear reduction unit and a motor controller; the first driving motor is in transmission connection with the differential through the first gear reduction unit, and the second driving motor is in transmission connection with the differential through the second gear reduction unit; the transmission ratio of the first gear reduction unit is smaller than that of the second gear reduction unit; the first driving motor and the second driving motor are respectively in electrical connection with the motor controller; wherein the first driving motor is a synchronous motor, and the second driving motor is an asynchronous motor.

2. The dual electric drive axle system of claim 1, wherein, The first driving motor is a flat wire permanent magnet synchronous motor, and the second driving motor is a flat wire induction asynchronous motor.

3. The dual electric drive axle system of claim 1, wherein, The first driving motor and the second driving motor are symmetrically arranged about the center of the differential.

4. The dual electric drive axle system of claim 1, wherein, The first gear reduction unit is composed of a first gear and a second gear, the first gear is coaxial with the first driving motor, the first gear is in meshing connection with the second gear, and the rotating shaft of the second gear is connected with the differential; The second gear reduction unit is composed of a third gear, a fourth gear, a fifth gear and a sixth gear, the sixth gear is coaxial with the second driving motor, the sixth gear is in meshing connection with the fifth gear, the fifth gear is coaxial with the fourth gear, the fourth gear is in meshing connection with the third gear, and the third gear is in meshing connection with the second gear.

5. The dual electric drive axle system of claim 4, wherein, The first driving motor, the second driving motor, the differential, the first gear reduction unit and the second gear reduction unit are integrated in the axle housing of a driving rear axle.

6. A vehicle characterized by comprising: The vehicle is provided with one rear axle, and the rear axle is provided with the double electric drive axle system according to any one of claims 1-5; or The vehicle is provided with a plurality of rear axles, and at least two of the rear axles are respectively provided with the double electric drive axle system according to any one of claims 1-5. The vehicle is provided with a plurality of rear axles, and at least two of the rear axles are respectively provided with the double electric drive axle system according to any one of claims 1-5.

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