Electric drive axle control system and commercial vehicle

Abstract

The invention relates to the technical field of commercial vehicle electric drive axles, in particular to an electric drive axle control system and a commercial vehicle. The electric drive axle control system comprises a left second axle motor, a right second axle motor, a left second axle wheel, a right second axle wheel, a third axle motor, a differential mechanism, a left third axle wheel, a right third axle wheel and a controller. The left second-axle motor is connected with the left second-axle wheel through the left second-axle speed change mechanism, the right second-axle motor is connected with the right second-axle wheel through the right second-axle speed change mechanism, and the controller can control the driving torque of the left second-axle motor and the driving torque of the right second-axle motor respectively. The three-axle motor is connected with the differential mechanism through the three-axle speed change mechanism, and the differential mechanism is connected with the left three-axle wheel and the right three-axle wheel. And when the actual speed of the whole vehicle is greater than the preset high-speed limit value, the controller controls the three-axle motor to start and controls the left two-axle motor and the right two-axle motor to close. According to the electric drive axle control system and the commercial vehicle, the technical problems existing in an electric drive axle of an existing commercial vehicle are solved.

Description

Technical Field

[0001] The present application relates to the technical field of electric drive axles for commercial vehicles, and in particular to an electric drive axle control system and a commercial vehicle. Background Art

[0002] For commercial vehicle electric drive axles, traditional commercial vehicle electric drive axles usually include two configurations: distributed and centralized. Although the distributed configuration can achieve independent control of the left and right wheels, due to the large axle load of heavy commercial vehicles, speed control errors are prone to occur, causing tire wear, so it is rarely used.

[0003] The centralized configuration uses a single motor or dual motors, both of which require a shared mechanical differential to achieve torque distribution to the left and right sides. However, the centralized configuration cannot achieve separate control of the drives on both sides, and cannot meet the needs of chassis vector control. Summary of the invention

[0004] The purpose of this application is to provide an electric drive axle control system and a commercial vehicle, thereby solving the above-mentioned technical problems existing in the existing commercial vehicle electric drive axles.

[0005] According to the first aspect of the present application, an electric drive axle control system is provided, which includes a left second-bridge motor, a right second-bridge motor, a left second-bridge wheel, a right second-bridge wheel, a left second-bridge speed change mechanism, a right second-bridge speed change mechanism, a third-bridge motor, a differential, a left third-bridge wheel, a right third-bridge wheel, a third-bridge speed change mechanism and a controller; the left second-bridge motor is connected to the left second-bridge wheel through the left second-bridge speed change mechanism, and the right second-bridge motor is connected to the right second-bridge wheel through the right second-bridge speed change mechanism, and the controller can control the driving torque of the left second-bridge motor and the right second-bridge motor respectively; the third-bridge motor is connected to the differential through the third-bridge speed change mechanism, and the differential is connected to the left third-bridge wheel and the right third-bridge wheel respectively; the controller pre-stores a predetermined high-speed limit; when the actual vehicle speed is greater than the predetermined high-speed limit, the controller controls the third-bridge motor to start, and controls the left second-bridge motor and the right second-bridge motor to shut down.

[0006] In any of the above technical solutions, further, the controller pre-stores a first threshold value, and the controller can determine the target acceleration a of the vehicle according to the throttle input of the vehicle. t When the vehicle starts, the controller controls the three-bridge motor to start, and when the target acceleration of the vehicle is a t The actual acceleration of the vehicle is v When the difference between the left and right second bridge motors exceeds the first threshold value, the controller controls the left second bridge motor and the right second bridge motor to start until the actual acceleration a of the vehicle is v Reach the target acceleration a of the vehiclet , the controller controls the left second bridge motor and the right second bridge motor to turn off.

[0007] In any of the above technical solutions, further, the electric drive axle control system also includes a left first axle wheel, a right first axle wheel and a TCS system; the controller pre-stores a set value V th and a predetermined ideal vehicle speed value, the controller can determine the corresponding vehicle speed V according to the wheel speed of the left third bridge wheel 3L , determine the corresponding vehicle speed V according to the wheel speed of the right third bridge wheel 3R , and determine the corresponding vehicle speed V according to the wheel speeds of the left first bridge wheel and the right first bridge wheel fa ; When the vehicle starts, if (V 3L +V 3R ) / 2-V fa >V th , the TCS system is turned on, the controller controls the left second bridge motor and the right second bridge motor to start, and the three-bridge motor is turned off; during the operation of the left second bridge motor and the right second bridge motor, the controller controls the driving torque of the left second bridge motor and the right second bridge motor respectively, so that the vehicle speeds corresponding to the wheel speeds of the left second bridge wheel and the right second bridge wheel both reach the predetermined ideal vehicle speed value.

[0008] In any of the above technical solutions, further, the predetermined ideal vehicle speed value V t =(1+S)V fa , where S is the driving slip ratio; when the vehicle speeds corresponding to the wheel speeds of the left second bridge wheel and the right second bridge wheel of the whole vehicle are both the predetermined ideal vehicle speed value V t When the controller controls the three-bridge motor to start, the left second-bridge motor and the right second-bridge motor to shut down.

[0009] In any of the above technical solutions, further, the controller pre-stores a second threshold value, and the controller can determine the expected yaw angular velocity w according to the steering wheel input. t When the three-bridge motor recovers energy, the actual yaw angular velocity of the vehicle is w z and the desired yaw rate w of the vehicle t When the difference between the left and right second bridge motors exceeds the second threshold value, the controller controls the left second bridge motor or the right second bridge motor to start until the actual yaw angular velocity w of the vehicle is z The desired yaw rate w of the vehicle is reached t , the controller controls the left second bridge motor or the right second bridge motor to turn off.

[0010] In any of the above technical solutions, further, when the three-bridge motor recovers energy, when the actual yaw angular velocity w of the vehiclez and the desired yaw rate w of the vehicle t When the difference is positive, the controller increases the regenerative braking torque of the right second bridge motor; when the actual yaw angular velocity of the vehicle w z and the desired yaw rate w of the vehicle t When the difference is a negative value, the controller increases the regenerative braking torque of the left second bridge motor.

[0011] In any of the above technical solutions, further, the controller can determine the desired yaw rate w according to the steering wheel input. t ; When the vehicle turns left, the actual yaw angular velocity w of the vehicle z and the desired yaw rate w of the vehicle t When the difference is positive, the controller increases the driving torque of the left second bridge motor; when the actual yaw angular velocity w of the vehicle z and the desired yaw rate w of the vehicle t When the difference is a negative value, the controller increases the driving torque of the right second bridge motor; when the vehicle turns right, when the actual yaw angular velocity w of the vehicle z and the desired yaw rate w of the vehicle t When the difference is positive, the controller increases the driving torque of the right second bridge motor; when the actual yaw angular velocity w of the vehicle z and the desired yaw rate w of the vehicle t When the difference is a negative value, the controller increases the driving torque of the left second bridge motor.

[0012] In any of the above technical solutions, further, the controller can determine the corresponding wheel slip rate according to the wheel speed of the left first bridge wheel, determine the corresponding wheel slip rate according to the wheel speed of the right first bridge wheel, determine the corresponding wheel slip rate according to the wheel speed of the left second bridge wheel, determine the corresponding wheel slip rate according to the wheel speed of the right second bridge wheel, determine the corresponding wheel slip rate according to the wheel speed of the left third bridge wheel, and determine the corresponding wheel slip rate according to the wheel speed of the right third bridge wheel; when the whole vehicle brakes on the open road, if the wheel slip rate of the left first bridge wheel is greater than the wheel slip rate of the right first bridge wheel, and the wheel slip rate of the left second bridge wheel is greater than the wheel slip rate of the right second bridge wheel, and the wheel slip rate of the left third bridge wheel is greater than the wheel slip rate of the right third bridge wheel, then the controller controls the left first bridge wheel, the right first bridge wheel, the left second bridge wheel, the left third bridge wheel and the right third bridge wheel to brake, and controls the torque of the right second bridge motor to make the right second bridge wheel generate driving force;

[0013] When the whole vehicle is braking on an open road, if the wheel slip rate of the left first bridge wheel is smaller than the wheel slip rate of the right first bridge wheel, and the wheel slip rate of the left second bridge wheel is smaller than the wheel slip rate of the right second bridge wheel, and the wheel slip rate of the left third bridge wheel is smaller than the wheel slip rate of the right third bridge wheel, then the controller controls the braking of the left first bridge wheel, the right first bridge wheel, the right second bridge wheel, the left third bridge wheel and the right third bridge wheel, and controls the torque of the left second bridge motor so that the left second bridge wheel generates driving force.

[0014] In any of the above technical solutions, further, the three-bridge speed change mechanism includes a first shaft, a first gear, a second gear, a second shaft, a first gear driving gear, a second gear driving gear, a third shaft, a first gear driven gear, a second gear driven gear, a synchronizer, a third gear and a transmission member;

[0015] The three-axle motor is connected to the first gear through the first shaft, the first gear is meshed with the second gear, the second gear, the first gear driving gear, and the second gear driving gear are all fixed to the second shaft, the first gear driven gear and the second gear driven gear are both sleeved on the third shaft, the synchronizer and the third gear are both fixed to the third shaft, the synchronizer is arranged between the first gear driven gear and the second gear driven gear, the first gear driving gear is meshed with the first gear driven gear, the second gear driving gear is meshed with the second gear driven gear, the third gear is connected to the differential through the transmission member, and the differential is respectively connected to the left three-axle wheel and the right three-axle wheel through two half shafts.

[0016] According to a second aspect of the present application, a commercial vehicle is provided, comprising the electric drive axle control system as described above.

[0017] The electric drive axle control system of the present application includes a left second axle motor, a right second axle motor, a left second axle wheel, a right second axle wheel, a left second axle speed change mechanism, a right second axle speed change mechanism, a third axle motor, a differential, a left third axle wheel, a right third axle wheel, a third axle speed change mechanism and a controller. Among them, the left second axle motor is connected to the left second axle wheel through the left second axle speed change mechanism, the right second axle motor is connected to the right second axle wheel through the right second axle speed change mechanism, and the controller can control the driving torque of the left second axle motor and the right second axle motor respectively; the third axle motor is connected to the differential through the third axle speed change mechanism, and the differential is connected to the left third axle wheel and the right third axle wheel respectively; the controller stores a predetermined high-speed limit in advance; when the actual vehicle speed is greater than the predetermined high-speed limit, the controller controls the third axle motor to start, and controls the left second axle motor and the right second axle motor to shut down.

[0018] According to the above technical features, the beneficial effects of this application are:

[0019] The electric drive axle control system of the present application can independently control the driving torque of the left second axle motor and the right second axle motor to achieve independent control of the driving torque on the left and right sides; and when the vehicle is driving at high speed, the controller only controls the start of the third axle motor, so the vehicle can avoid excessive wear of the tires when turning at high speed. In other words, the electric drive axle control system of the present application can not only achieve independent control of the torque of the left and right wheels under special working conditions, but also ensure a reasonable distribution of the speed difference between the left and right wheels to prevent excessive wear of the tires when turning at high speed.

[0020] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 The overall principle schematic diagram of the electric drive axle control system of the embodiment of the present application is shown;

[0023] Figure 2 A schematic structural diagram of a three-bridge transmission mechanism according to an embodiment of the present application is shown.

[0024] Icons: 10-first shaft; 20-first gear; 30-second gear; 40-second shaft; 51-first gear driving gear; 52-second gear driving gear; 80-third shaft; 61-first gear driven gear; 62-second gear driven gear; 70-synchronizer; 90-third gear; 91-transmission member;

[0025] 100-left second bridge motor; 200-right second bridge motor; 300-left second bridge wheel; 400-right second bridge wheel; 500-third bridge motor; 600-differential; 700-left third bridge wheel; 800-right third bridge wheel; 900-controller; 1000-third bridge speed change mechanism; 2000-left second bridge speed change mechanism; 3000-right second bridge speed change mechanism. DETAILED DESCRIPTION

[0026] The following specific embodiments are provided to help the reader obtain a comprehensive understanding of the methods, devices and / or systems described herein. However, after understanding the disclosure of the present application, various changes, modifications and equivalents of the methods, devices and / or systems described herein will be apparent. For example, the order of operations described herein is merely an example, and is not limited to the order set forth herein, but in addition to the operations that must occur in a particular order, changes that will be apparent after understanding the disclosure of the present application may be made. In addition, in order to improve clarity and brevity, descriptions of features known in the art may be omitted.

[0027] The features described herein may be implemented in different forms and should not be interpreted as being limited to the examples described herein. Rather, the examples described herein have been provided only to illustrate some of the many possible ways of implementing the methods, devices and / or systems described herein that will be apparent after understanding the disclosure of the present application.

[0028] Throughout the specification, when an element (such as a layer, a region, or a substrate) is described as being “on”, “connected to”, “bound to”, “over”, or “covering” another element, it may be directly “on”, “connected to”, “bound to”, “over”, or “covering” another element, or one or more other elements may be present between them. In contrast, when an element is described as being “directly on”, “directly connected to”, “directly bound to”, “directly over”, or “directly covering” another element, there may be no other elements present between them.

[0029] As used herein, the term "and / or" includes any one of the associated listed items and any combination of any two or more items.

[0030] Although terms such as "first," "second," and "third" may be used herein to describe various members, components, regions, layers, or portions, these members, components, regions, layers, or portions are not limited by these terms. Rather, these terms are only used to distinguish one member, component, region, layer, or portion from another member, component, region, layer, or portion. Therefore, without departing from the teachings of the examples described herein, the first member, component, region, layer, or portion referred to may also be referred to as the second member, component, region, layer, or portion.

[0031] For ease of description, spatial relational terms such as "above", "upper", "below", and "lower" may be used herein to describe the relationship of one element to another element as shown in the accompanying drawings. Such spatial relational terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the accompanying drawings. For example, if the device in the accompanying drawings is turned over, an element described as being "above" or "upper" relative to another element will subsequently be "below" or "lower" relative to the other element. Therefore, the term "above" includes both "above" and "below" orientations depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relational terms used herein will be interpreted accordingly.

[0032] The terms used herein are only used to describe various examples and are not used to limit the present disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms "include", "comprise" and "have" list the stated features, quantities, operations, components, elements and / or their combinations that exist, but do not exclude the existence or addition of one or more other features, quantities, operations, components, elements and / or their combinations.

[0033] Variations in the shapes shown in the drawings may occur due to manufacturing techniques and / or tolerances. Therefore, the examples described herein are not limited to the specific shapes shown in the drawings but include variations in shapes that occur during manufacturing.

[0034] The features of the examples described herein may be combined in various ways that will be apparent after understanding the disclosure of the present application. In addition, although the examples described herein have various configurations, other configurations are possible as will be apparent after understanding the disclosure of the present application.

[0035] Before this application was filed, for commercial vehicle electric drive axles, traditional commercial vehicle electric drive axles usually include two configurations: distributed and centralized. Although the distributed configuration can achieve independent control of the left and right wheels, it is rarely used because of the large axle load of heavy commercial vehicles, which is prone to speed control errors and tire wear. The centralized configuration uses a single motor or dual motors, both of which need to use a shared mechanical differential to achieve torque distribution to the left and right sides, but the centralized configuration cannot achieve separate control of the drives on both sides and cannot meet the needs of chassis vector control.

[0036] In view of this, the first aspect of the present application provides an electric drive axle control system, thereby solving the above technical problems existing in the existing commercial vehicle electric drive axles. Figure 1 and Figure 2The electric drive axle control system according to some embodiments of the present application is described.

[0037] like Figure 1 As shown, the electric drive axle control system of the present application is applied to a commercial vehicle with multi-axle drive. The electric drive axle control system includes a left second axle motor 100, a right second axle motor 200, a left second axle wheel 300, a right second axle wheel 400, a left second axle speed change mechanism 2000, a right second axle speed change mechanism 3000, a third axle motor 500, a differential 600, a left third axle wheel 700, a right third axle wheel 800, a third axle speed change mechanism 1000 and a controller 900.

[0038] Among them, the left second bridge motor 100 is connected to the left second bridge wheel 300 through the left second bridge speed change mechanism 2000, and the right second bridge motor 200 is connected to the right second bridge wheel 400 through the right second bridge speed change mechanism 3000, and the controller 900 can respectively control the driving torque of the left second bridge motor 100 and the right second bridge motor 200. In other words, the two bridges adopt a left-right independent drive scheme, and two single-side drive motors drive the left second bridge wheel 300 and the right second bridge wheel 400 separately through the single-side speed change mechanism, and can independently control the driving torque and regenerative braking torque of the left second bridge wheel 300 and the right second bridge wheel 400.

[0039] Among them, the three-bridge motor 500 is connected to the differential 600 through the three-bridge speed change mechanism 1000, and the differential 600 is connected to the left three-bridge wheel 700 and the right three-bridge wheel 800 through two half shafts. In other words, the three bridges are centrally driven by a single motor, and the driving torque of the three-bridge motor 500 passes through the three-bridge speed change mechanism 1000 and the differential 600, and then passes through the left and right half shafts to drive the left three-bridge wheel 700 and the right three-bridge wheel 800 respectively.

[0040] Among them, the left second bridge motor 100 , the right second bridge motor 200 and the third bridge motor 500 work under the control of the controller 900 .

[0041] In an embodiment of the present application, the electric drive axle control system also includes a left axle wheel and a right axle wheel (front axle, not shown in the figure).

[0042] In the embodiments of the present application, Figure 2 As shown, the three-axle transmission mechanism 1000 includes a first shaft 10, a first gear 20, a second gear 30, a second shaft 40, a first gear driving gear 51, a second gear driving gear 52, a third shaft 80, a first gear driven gear 61, a second gear driven gear 62, a synchronizer 70, a third gear 90 and a transmission member 91.

[0043] Among them, the three-bridge motor 500 is connected to the first gear 20 through the first shaft 10, the first gear 20 is meshed with the second gear 30, the second gear 30, the first gear driving gear 51, and the second gear driving gear 52 are all fixed to the second shaft 40, the first gear driven gear 61 and the second gear driven gear 62 are both sleeved on the third shaft 80, the synchronizer 70 and the third gear 90 are both fixed to the third shaft 80, the synchronizer 70 is arranged between the first gear driven gear 61 and the second gear driven gear 62, the first gear driving gear 51 is meshed with the first gear driven gear 61, the second gear driving gear 52 is meshed with the second gear driven gear 62, the third gear 90 is connected to the differential 600 through the transmission member 91, and the differential 600 is respectively connected to the left third bridge wheel 700 and the right third bridge wheel 800 through two half shafts.

[0044] With such arrangement, the three-axle transmission mechanism 1000 adopts a relatively simple parallel shaft type shifting mechanism, which occupies a small volume, has low cost, is easy to assemble, and has high transmission accuracy and efficiency.

[0045] The power flow is: first shaft 10-first gear 20-second gear 30-second shaft 40-first gear driving gear 51+second gear driving gear 52-first gear driven gear 61+second gear driven gear 62-synchronizer 70-third shaft 80-third gear 90-transmission member 91-differential 600-left and right half shafts-left third bridge wheel 700+right third bridge wheel 800. When the vehicle is in first gear, the synchronizer 70 is combined with the first gear driven gear 61; when the vehicle is in second gear, the synchronizer 70 is combined with the second gear driven gear 62.

[0046] In the embodiments of the present application, Figure 1 As shown, the left second-bridge transmission mechanism 2000 and the right second-bridge transmission mechanism 3000 have the same structure, and both include two gears meshing with each other.

[0047] In an embodiment of the present application, the controller 900 stores a predetermined high-speed limit in advance; when the actual vehicle speed is greater than the predetermined high-speed limit, the controller 900 controls the three-bridge motor 500 to start, and controls the left second-bridge motor 100 and the right second-bridge motor 200 to shut down.

[0048] As described above, the electric drive axle control system of the present application can independently control the driving torque of the left second axle motor 100 and the right second axle motor 200 to achieve independent control of the left and right driving torques; and when the vehicle is traveling at high speed, the controller 900 only controls the third axle motor 500 to start, so the vehicle can avoid excessive wear of the tires when traveling on high-speed curves. In other words, the electric drive axle control system of the present application can not only achieve independent control of the left and right wheel torques under special working conditions, but also ensure reasonable distribution of the left and right wheel speed difference to prevent excessive wear of the tires when traveling on high-speed curves.

[0049] Based on the above electric drive axle control system, the electric drive axle control system of the present application includes control modes under different working states, so that the system has the ability of vehicle vector control. The system specifically has the following working modes:

[0050] Normal start mode:

[0051] The controller 900 stores a first threshold value in advance, and the controller 900 can determine the target acceleration a of the vehicle according to the throttle input of the vehicle. t When the vehicle starts, the controller 900 controls the three-bridge motor 500 to start. t The actual acceleration of the vehicle is v When the difference between the left and right second bridge motors 100 and 200 exceeds the first threshold value, the controller 900 controls the left second bridge motor 100 and the right second bridge motor 200 to start until the actual acceleration a of the vehicle is v Reach the target acceleration a of the vehicle t , the controller 900 controls the left second bridge motor 100 and the right second bridge motor 200 to be turned off.

[0052] Specifically, in the normal starting stage, the third bridge motor 500 is used first to start, and the second bridge is in the follow-up idling mode. The controller 900 determines the target acceleration a of the vehicle according to the driver's throttle. t (characteristics can be calibrated), and combined with the actual vehicle acceleration a v (which can be calculated by the vehicle speed), adjust the driving torque of the three-bridge motor 500 to accelerate the vehicle according to the expected acceleration; when a t with a v When the integral of the difference between the left and right bridge motors 100 and 200 exceeds the first threshold value A, it is considered that the driving capacity of the three-bridge motor 500 is insufficient to accelerate the vehicle as expected by the driver. Then, on the basis of the three-bridge motor 500, the left second bridge motor 100 and the right second bridge motor 200 are controlled to input driving torque to jointly drive the vehicle to accelerate, so as to improve the acceleration performance of the vehicle and make it reach the target acceleration a. t .

[0053] TCS working mode:

[0054] The controller 900 stores a preset value V th and the predetermined ideal vehicle speed value, the controller 900 can determine the corresponding vehicle speed V according to the wheel speed of the left third bridge wheel 700 3L , determine the corresponding vehicle speed V according to the wheel speed of the right third bridge wheel 800 3R , and determine the corresponding vehicle speed V according to the wheel speeds of the left and right axle wheels fa When the vehicle starts, if (V 3L +V 3R ) / 2-V fa >V th, the TCS system is turned on, the controller 900 controls the left second bridge motor 100 and the right second bridge motor 200 to start, and the third bridge motor 500 is turned off. During the operation of the left second bridge motor 100 and the right second bridge motor, the controller 900 controls the driving torque of the left second bridge motor 100 and the right second bridge motor respectively, so that the vehicle speed corresponding to the wheel speed of the left second bridge wheel 300 and the right second bridge wheel 400 reaches the predetermined ideal vehicle speed value.

[0055] Specifically, the TCS working mode. When slipping occurs at the start and the TCS system needs to intervene, for a three-axle car with a differential, it is easy for one side of the wheel to slip, thereby limiting the torque (most typical on split roads, in fact, on low-adhesion roads due to the slight difference in the road adhesion coefficient between the left and right wheels, it is also easy for one side of the wheel to slip). At this time, for a three-axle car with a differential, the actual torque that can be achieved can only be increased by applying brakes to the wheel on the slipping side (BTC function in TCS).

[0056] To solve the above problem, in this case (when TCS is activated), the second-bridge drive is used first. The left second-bridge motor 100 and the right second-bridge motor can independently output driving force according to their respective working states under the control of the controller 900 (ECU), avoiding the influence of the differential 600. Therefore, on various road surfaces (including split road surfaces and low-adhesion road surfaces), each wheel can exert its maximum ground adhesion, provide the maximum driving torque, and obtain the best starting ability. The specific workflow is as follows:

[0057] 1. When starting, the system is in the normal starting state in the normal starting mode. During the starting process, the vehicle speed V corresponding to the rotation speed of the left third bridge wheel 700 and the right third bridge wheel 800 is detected in real time. 3L 、V 3R , and the average vehicle speed V corresponding to the wheel speeds of the left and right bridge wheels fa , when (V 3L -V 3R ) / 2-V fa Exceeding the set value V th (Vt h It can be calibrated as a fixed value or as a value related to the actual vehicle speed), which means that the drive wheel has excessive slip compared to the vehicle, and the TCS system drive anti-skid function is activated. At this time, in order to better control the TCS function, the drive function gradually transitions from the conventional three-axle to the second-axle, and the second-axle takes over the vehicle drive task.

[0058] 2. During the above switching process, the torque T of the three-bridge motor 500 at the time of activating the TCS function is 0 Based on this, the torque of the three-bridge motor 500 is gradually reduced according to the gradient ΔT (which can be calibrated according to the actual situation): T 4 =T0 -ΔT t , where t is the time from the activation of the TCS function to the present moment. The torque of the left second bridge motor 100 and the right second bridge motor 200 gradually increases according to the gradient ΔT (which can be calibrated according to actual conditions): T 1 =T 0 +ΔT t , and evenly distributed between the left second bridge motor 100 and the right second bridge motor 200. In this way, the driving torque can be gradually transferred from the third bridge to the second bridge, which is convenient for subsequent control.

[0059] 3. After the driving torque is transferred to the second bridge, since the left second bridge motor 100 and the right second bridge motor 200 of the second bridge do not affect each other and can be independently controlled, the driving torque of the left second bridge motor 100 and the right second bridge motor 200 can be controlled according to the rotation speed of the left second bridge wheel 300 and the right second bridge wheel 400 of the second bridge in the subsequent driving process to achieve the best control effect. The ideal driving slip rate for acceleration is (can be 15%, the specific value can be calibrated according to the actual vehicle parameters), then the predetermined ideal vehicle speed value V of the left second bridge wheel 300 and the right second bridge wheel 400 of the second bridge is t =(1+S)V fa The controller 900 monitors the vehicle speed V corresponding to the wheel speeds of the left second bridge wheel 300 and the right second bridge wheel 400. 2L 、V 2R , with V t As the target value, the driving torque of the motors on both sides is adjusted in real time through closed-loop control (through PID and other algorithms), so that the left second-bridge motor 100 and the right second-bridge motor 200 are maintained in the ideal driving slip rate working range to achieve the optimal acceleration capability.

[0060] High speed driving mode:

[0061] The controller 900 stores a predetermined high-speed limit value in advance. When the actual vehicle speed is greater than the predetermined high-speed limit value, the controller 900 controls the three-bridge motor 500 to start, and controls the left second bridge motor 100 and the right second bridge motor 200 to shut down.

[0062] Specifically, in high-speed driving mode, in order to reduce the error caused by the independent control of the left and right wheel speeds when driving on a curve, which may cause excessive tire wear, the three-axle drive is used first in this mode. At this time, the differential 600 of the three-axle can automatically perform differential speed control on the left and right wheels according to the turning radius, thereby achieving minimum tire wear. The specific implementation method is as follows: when it is determined that the vehicle speed is greater than a predetermined high-speed limit (threshold value V th2, generally 40km / h), if it was in the normal starting mode before, the TCS working mode will be disabled later and the three-axle drive will be maintained; if it was in the TCS working mode before, the second axle will be driven. After entering the high-speed driving mode, the second axle motor torque (referring to the sum of the torque of the left second axle motor 100 and the right second axle motor 200) will transfer the driving torque to the third axle according to the torque gradient method of the TCS working mode. After that, the third axle will be driven. When maintaining high-speed driving, the transmission is transmitted through the differential 600 to ensure that the tires on both sides do not produce excessive wear when driving on curves.

[0063] Energy recovery mode:

[0064] The controller 900 stores the second threshold value in advance, and the controller 900 can determine the expected yaw rate w according to the steering wheel input. t When the three-bridge motor 500 recovers energy, the actual yaw rate of the vehicle is w z and the desired yaw rate w of the vehicle t When the difference between the left and right second bridge motors 100 and 200 exceeds the second threshold value, the controller 900 controls the left second bridge motor 100 or the right second bridge motor 200 to start, until the actual yaw angular velocity w of the vehicle is z The desired yaw rate w of the vehicle is reached t , the controller 900 controls the left second bridge motor 100 or the right second bridge motor 200 to turn off. When the energy of the third bridge motor 500 is recovered, when the actual yaw angular velocity of the vehicle is w z and the desired yaw rate w of the vehicle t When the difference is positive, the controller 900 increases the regenerative braking torque of the right second bridge motor 200. When the actual yaw angular velocity w of the vehicle z and the desired yaw rate w of the vehicle t When the difference is a negative value, the controller 900 increases the regenerative braking torque of the left second bridge motor 100.

[0065] Specifically, energy recovery mode. When performing energy recovery, the third-bridge motor 500 (the central motor of the third bridge) is used first to recover braking energy to ensure that the regenerative braking forces on the left and right sides are equal, which is conducive to maintaining directional stability. When the vehicle sways slightly due to steering, road surface, etc., the regenerative braking of the wheels on the corresponding side of the second bridge can be used to adjust the body posture and keep the vehicle moving in the desired direction. The specific implementation method is that when the third bridge is performing energy recovery, if the actual yaw angular velocity w z (measured by the IMU provided in the controller 900) and the desired yaw rate w expected by the driver tWhen the deviation between the steering angle input of the driver and the Ackerman formula is greater than the second threshold value, it means that the actual steering of the vehicle body is inconsistent with the expected steering of the driver. Then, the regenerative braking torque of the wheel on one side of the second bridge can be controlled to compensate. The specific method is as follows: when w z -w t is a positive value (left / counterclockwise steering direction is positive), the regenerative braking torque of the right second bridge motor 200 is increased, and vice versa when w z -w t When it is a negative value, the regenerative braking torque of the left second bridge motor 100 is increased. The specific value of the increase can be closed-loop controlled by PID or other methods, or can be open-loop regulated by a fixed gradient increase method.

[0066] Wheel end vector control mode:

[0067] The controller 900 can determine the desired yaw rate w according to the steering wheel input. t When the vehicle turns left, the actual yaw angular velocity w of the vehicle is z and the desired yaw rate w of the vehicle t When the difference is positive, the controller 900 increases the driving torque of the left second bridge motor 100; when the actual yaw angular velocity w of the vehicle is z and the desired yaw rate w of the vehicle t When the difference is negative, the controller 900 increases the driving torque of the right second bridge motor 200. When the vehicle turns right, when the actual yaw angular velocity w of the vehicle z and the desired yaw rate w of the vehicle t When the difference is positive, the controller 900 increases the driving torque of the right second bridge motor 200; when the actual yaw angular velocity w of the vehicle is z and the desired yaw rate w of the vehicle t When the difference is a negative value, the controller 900 increases the driving torque of the left second bridge motor 100.

[0068] Specifically, the wheel-end vector control mode. In this mode, the system can generate a certain yaw moment for the whole vehicle by controlling the torque of the left second-bridge motor 100 or the right second-bridge motor 200 separately, thereby realizing some functions of using drive to assist the vehicle body stability. For example, when the system has understeer, a system that does not have wheel-end vector control capability can only assist the vehicle in yaw control by applying brakes to the inner front wheel or rear wheel. For this system, the driving torque of the outer wheel of the second bridge can also be controlled to achieve the same correction function for understeer. For oversteer conditions, active yaw control can also be achieved by applying driving force to the inner drive wheel of the second bridge.

[0069] Braking mode on open road:

[0070] The controller 900 can determine the corresponding wheel slip rate according to the wheel speed of the left first bridge wheel, determine the corresponding wheel slip rate according to the wheel speed of the right first bridge wheel, determine the corresponding wheel slip rate according to the wheel speed of the left second bridge wheel 300, determine the corresponding wheel slip rate according to the wheel speed of the right second bridge wheel 400, determine the corresponding wheel slip rate according to the wheel speed of the left third bridge wheel 700, and determine the corresponding wheel slip rate according to the wheel speed of the right third bridge wheel 800. When the vehicle is braking on an open road, if the wheel slip rate of the left first bridge wheel is greater than the wheel slip rate of the right first bridge wheel, and the wheel slip rate of the left second bridge wheel 300 is greater than the wheel slip rate of the right second bridge wheel 400, and the wheel slip rate of the left third bridge wheel 700 is greater than the wheel slip rate of the right third bridge wheel 800, the controller 900 controls the left first bridge wheel, the right first bridge wheel, the left second bridge wheel 300, the left third bridge wheel 700 and the right third bridge wheel 800 to brake, and controls the torque of the right second bridge motor 200 to make the right second bridge wheel 400 generate a driving force Ft. On the contrary, when the whole vehicle is braking on an open road, if the wheel slip rate of the left first bridge wheel is smaller than the wheel slip rate of the right first bridge wheel, and the wheel slip rate of the left second bridge wheel 300 is smaller than the wheel slip rate of the right second bridge wheel 400, and the wheel slip rate of the left third bridge wheel 700 is smaller than the wheel slip rate of the right third bridge wheel 800, then the controller 900 controls the left first bridge wheel, the right first bridge wheel, the right second bridge wheel 400, the left third bridge wheel 700 and the right third bridge wheel 800 to brake, and controls the torque of the left second bridge motor 100, so that the left second bridge wheel 300 generates a driving force Ft.

[0071] Specifically, when braking on a split road, under normal circumstances, the braking force on the high-attachment side is much greater than that on the low-attachment side, which will generate a torque that deflects the entire vehicle toward the high-attachment side, making it difficult to maintain directional stability. Under this condition, the high-attachment side second bridge can be left unbraked, and the other wheels can be braked normally. By applying a driving torque to the high-attachment side wheels of the second bridge, a yaw torque generated by the unbalanced braking force is generated to assist in maintaining the directional stability of the vehicle, thereby improving both the braking strength and directional stability. The specific implementation method is: when braking, the slip rate of each wheel is monitored in real time (the percentage of the difference between the vehicle speed corresponding to the wheel speed and the reference vehicle speed, where the reference vehicle speed can be calculated by the integral method, the wheel speed vertex method, etc., which is not described in detail outside the content of the present invention). If the slip rate of the left wheel of the first, second, and third bridges is greater than the slip rate of the right wheel, it means that the current road is low on the left and high on the right (the left side is low-attachment and the right side is high-attachment). At this time, since the braking force on the right side is greater than that on the left side, the vehicle will deflect to the right side. At this time, the braking force is no longer applied to the right second bridge wheel 400, but it is made to generate a certain driving force F t , to offset the rightward deflection of the vehicle. t The specific value of is to make the actual yaw angular velocity w of the vehicle zThe value is determined by making it as close to 0 as possible, which can be achieved through PID algorithm, table lookup and other methods.

[0072] According to a second aspect of the present application, a commercial vehicle is provided, comprising the electric drive axle control system as described above.

[0073] In summary, the present application provides an electric drive axle control system for the torque vector control needs of the intelligent chassis of commercial vehicles. The electric drive axle control system can independently control the driving torque of the left second axle motor 100 and the right second axle motor 200 to achieve independent control of the driving torque on the left and right sides; and when the whole vehicle is traveling at high speed, the controller 900 only controls the start of the third axle motor 500, so the whole vehicle can avoid excessive wear of the tires when turning at high speed. In other words, the electric drive axle control system of the present application can not only realize the separate control of the left and right wheel torque under special working conditions, but also ensure the reasonable distribution of the left and right wheel speed difference when turning at high speed to prevent excessive wear of the tires, and meet the control requirements of the intelligent domain control chassis.

[0074] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present application, which are used to illustrate the technical solutions of the present application rather than to limit them. The protection scope of the present application is not limited thereto. Although the present application has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that any technician familiar with this technical field can still modify the technical solutions recorded in the aforementioned embodiments within the technical scope disclosed in the present application, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be covered by the protection scope of the present application.

Claims

1. An electric drive axle control system, characterized in that: The electric drive axle control system includes a left second axle motor, a right second axle motor, a left second axle wheel, a right second axle wheel, a left second axle speed change mechanism, a right second axle speed change mechanism, a third axle motor, a differential, a left third axle wheel, a right third axle wheel, a third axle speed change mechanism and a controller; The left second bridge motor is connected to the left second bridge wheel through the left second bridge speed change mechanism, and the right second bridge motor is connected to the right second bridge wheel through the right second bridge speed change mechanism, and the controller can control the driving torque of the left second bridge motor and the right second bridge motor respectively; The three-bridge motor is connected to the differential through the three-bridge speed change mechanism, and the differential is connected to the left three-bridge wheel and the right three-bridge wheel respectively; The controller pre-stores a predetermined high-speed limit value; When the actual vehicle speed is greater than the predetermined high speed limit, the controller controls the three-bridge motor to start, and controls the left second-bridge motor and the right second-bridge motor to shut down.

2. The electric drive axle control system according to claim 1, characterized in that: The controller stores a first threshold value in advance, and the controller can determine the target acceleration a of the vehicle according to the throttle input of the vehicle. t ; When the vehicle starts, the controller controls the three-bridge motor to start. When the target acceleration a of the vehicle t The actual acceleration of the vehicle is v When the difference between the left and right second bridge motors exceeds the first threshold value, the controller controls the left second bridge motor and the right second bridge motor to start until the actual acceleration a of the vehicle is v Reach the target acceleration a of the vehicle t , the controller controls the left second bridge motor and the right second bridge motor to turn off.

3. The electric drive axle control system according to claim 2, characterized in that: The electric drive axle control system also includes a left first axle wheel, a right first axle wheel and a TCS system; The controller stores a set value V in advance. th and a predetermined ideal vehicle speed value, the controller can determine the corresponding vehicle speed V according to the wheel speed of the left third bridge wheel 3L , determine the corresponding vehicle speed V according to the wheel speed of the right third bridge wheel 3R , and determine the corresponding vehicle speed V according to the wheel speeds of the left first bridge wheel and the right first bridge wheel fa ; When the vehicle starts, if (V 3L +V 3R ) / 2-V fa >V th , the TCS system is turned on, the controller controls the left second bridge motor and the right second bridge motor to start, and the third bridge motor is turned off; During the operation of the left second axle motor and the right second axle motor, the controller controls the driving torque of the left second axle motor and the right second axle motor respectively, so that the vehicle speeds corresponding to the wheel speeds of the left second axle wheels and the right second axle wheels both reach the predetermined ideal vehicle speed value.

4. The electric drive axle control system according to claim 3, characterized in that: The predetermined ideal vehicle speed value V t =(1+S)V fa , where S is the driving slip ratio; When the vehicle speeds corresponding to the wheel speeds of the left second bridge wheel and the right second bridge wheel of the vehicle are both the predetermined ideal vehicle speed value V t When the controller controls the three-bridge motor to start, the left second-bridge motor and the right second-bridge motor to shut down.

5. The electric drive axle control system according to claim 1, characterized in that: The controller pre-stores a second threshold value, and the controller can determine the desired yaw rate w according to the steering wheel input. t , When the three-bridge motor recovers energy, the actual yaw angular velocity of the vehicle is w z and the desired yaw rate w of the vehicle t When the difference between the left and right second bridge motors exceeds the second threshold value, the controller controls the left second bridge motor or the right second bridge motor to start until the actual yaw angular velocity w of the vehicle is z The desired yaw rate w of the vehicle is reached t , the controller controls the left second bridge motor or the right second bridge motor to turn off.

6. The electric drive axle control system according to claim 5, characterized in that: When the three-bridge motor recovers energy, the actual yaw angular velocity of the vehicle is w z and the desired yaw rate w of the vehicle t When the difference is a positive value, the controller increases the regenerative braking torque of the right second bridge motor; When the actual yaw rate of the vehicle w z The desired yaw rate w of the vehicle t When the difference is a negative value, the controller increases the regenerative braking torque of the left second bridge motor.

7. The electric drive axle control system according to claim 1, characterized in that: The controller can determine the desired yaw rate w according to the steering wheel input. t ; When the vehicle turns left, the actual yaw angular velocity w of the vehicle z and the desired yaw rate w of the vehicle t When the difference is positive, the controller increases the driving torque of the left second bridge motor; when the actual yaw angular velocity w of the vehicle z and the desired yaw rate w of the vehicle t When the difference is a negative value, the controller increases the driving torque of the right second bridge motor; When the vehicle turns right, the actual yaw angular velocity w of the vehicle is z and the desired yaw rate w of the vehicle t When the difference is positive, the controller increases the driving torque of the right second bridge motor; when the actual yaw angular velocity w of the vehicle z and the desired yaw rate w of the vehicle t When the difference is a negative value, the controller increases the driving torque of the left second bridge motor.

8. The electric drive axle control system according to claim 3, characterized in that: The controller is capable of determining the corresponding wheel slip ratio according to the wheel speed of the left first bridge wheel, determining the corresponding wheel slip ratio according to the wheel speed of the right first bridge wheel, determining the corresponding wheel slip ratio according to the wheel speed of the left second bridge wheel, determining the corresponding wheel slip ratio according to the wheel speed of the right second bridge wheel, determining the corresponding wheel slip ratio according to the wheel speed of the left third bridge wheel, and determining the corresponding wheel slip ratio according to the wheel speed of the right third bridge wheel; When the vehicle is braking on an open road, if the wheel slip rate of the left first bridge wheel is greater than the wheel slip rate of the right first bridge wheel, and the wheel slip rate of the left second bridge wheel is greater than the wheel slip rate of the right second bridge wheel, and the wheel slip rate of the left third bridge wheel is greater than the wheel slip rate of the right third bridge wheel, the controller controls the left first bridge wheel, the right first bridge wheel, the left second bridge wheel, the left third bridge wheel and the right third bridge wheel to brake, and controls the torque of the right second bridge motor to make the right second bridge wheel generate driving force; When the whole vehicle is braking on an open road, if the wheel slip rate of the left first bridge wheel is smaller than the wheel slip rate of the right first bridge wheel, and the wheel slip rate of the left second bridge wheel is smaller than the wheel slip rate of the right second bridge wheel, and the wheel slip rate of the left third bridge wheel is smaller than the wheel slip rate of the right third bridge wheel, then the controller controls the braking of the left first bridge wheel, the right first bridge wheel, the right second bridge wheel, the left third bridge wheel and the right third bridge wheel, and controls the torque of the left second bridge motor so that the left second bridge wheel generates driving force.

9. The electric drive axle control system according to any one of claims 1 to 8, characterized in that: The three-axle speed change mechanism comprises a first shaft, a first gear, a second gear, a second shaft, a first gear driving gear, a second gear driving gear, a third shaft, a first gear driven gear, a second gear driven gear, a synchronizer, a third gear and a transmission member; The three-axle motor is connected to the first gear through the first shaft, the first gear is meshed with the second gear, the second gear, the first gear driving gear, and the second gear driving gear are all fixed to the second shaft, the first gear driven gear and the second gear driven gear are both sleeved on the third shaft, the synchronizer and the third gear are both fixed to the third shaft, the synchronizer is arranged between the first gear driven gear and the second gear driven gear, the first gear driving gear is meshed with the first gear driven gear, the second gear driving gear is meshed with the second gear driven gear, the third gear is connected to the differential through the transmission member, and the differential is respectively connected to the left three-axle wheel and the right three-axle wheel through two half shafts.

10. A commercial vehicle, characterized in that: It comprises an electric drive axle control system as claimed in any one of claims 1 to 9.

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