Method and system for monitoring health of transmission of electrically driven axle assembly

Abstract

The invention relates to a method for monitoring the health of a transmission (12) of an electric axle assembly (1) of a vehicle, in particular of an electric commercial vehicle, the electric axle assembly (1) further comprising an electric machine (11) for drivingly coupling to the transmission (12), the method comprises at least the following detection processes: in a state in which the transmission device (12) is only in transmission coupling with the motor (11), the motor (11) is in a rotating state for at least a period of time; detecting a state change characteristic of the motor (11); and monitoring a health condition of the transmission (12) based on the state change characteristic. The invention also relates to a corresponding system (3) for monitoring the health of a transmission (12) of an electric axle assembly (1) of a vehicle and to a corresponding computer-readable program carrier. According to some embodiments of the invention, lower cost and more reliable detection results can be realized.

Description

Technical Field

[0001] The invention relates to a method for monitoring the health of a transmission of an electric drive axle assembly of a vehicle, in particular an electric commercial vehicle, a corresponding system for monitoring the health of a transmission of an electric drive axle assembly of a vehicle, and a corresponding computer program product. Background Art

[0002] With the increasing awareness of environmental protection and the promotion of relevant policies in various countries, electric vehicles have developed rapidly in recent years and are gradually replacing traditional fuel vehicles. As a type of vehicle, the electrification of commercial vehicles also shows a great development trend.

[0003] For the electrification of commercial vehicles, the main task is to select the best powertrain system for the vehicle. Today, although long-axis motors still occupy a considerable proportion of the market, electric drive axles in which the drive motor and transmission are kept on, especially integrated on the axle, are receiving more and more attention and research and development because they can improve the efficiency of the powertrain and save more battery space. However, an important disadvantage of this electric drive axle is that as an unsprung structure, it will be subjected to high vibration during vehicle driving. This high vibration will bring great risks and challenges to the health of the electric drive axle, especially the motor and transmission.

[0004] Transmissions usually include gears and bearings. Compared with traditional vehicles, transmissions used in electric drive axles usually operate at higher speeds. Therefore, in harsh working environments with high vibration, transmissions become more prone to failure. In particular, the bearings of transmissions are key components, which is a particularly prominent problem. Therefore, it is necessary to monitor the health of transmissions, especially their bearings, in order to detect and eliminate faults in a timely manner.

[0005] At present, acceleration sensors are usually used for this kind of health status monitoring. Acceleration sensors are set in the appropriate area of ​​the electric drive axle, especially the transmission device to monitor the vibration signal, and monitor the health status of the transmission device based on the vibration signal and through a certain algorithm, so as to timely detect potential failures of the transmission device. However, the arrangement of acceleration sensors is difficult, and acceleration sensors also increase the cost of the entire system. The vibration of the vehicle itself will also interfere with the monitoring.

[0006] Therefore, it is desirable to be able to monitor the health status of the transmission simply and reliably to facilitate decisions regarding fault repair or predictive maintenance. Summary of the invention

[0007] In order to overcome at least one of the above-mentioned disadvantages and / or other possible disadvantages that may not be mentioned herein, the object of the present invention is to provide an improved method for monitoring the health status of a transmission device of an electric drive axle assembly of a vehicle, a corresponding system for monitoring the health status of a transmission device of an electric drive axle assembly of a vehicle, and a corresponding computer program product.

[0008] According to a first aspect of the present invention, a method for monitoring the health status of a transmission device of an electric drive axle assembly of a vehicle, especially an electric commercial vehicle, is provided, wherein the electric drive axle assembly also includes a motor for transmission coupling with the transmission device, and the method includes at least the following detection processes: keeping the motor in a rotating state for at least a period of time when the transmission device is only transmission coupled to the motor; detecting the state change characteristics of the motor; and monitoring the health status of the transmission device, especially its bearings and / or gears based on the state change characteristics.

[0009] Preferably, the motor and the transmission device are integrated on the electric drive axle, so that the path of the transmission device is shorter and the monitoring of the health status is more reliable.

[0010] According to an optional embodiment of the present invention, the detection process is also required to meet at least one of the following conditions to be allowed to be executed: the speed of the vehicle is zero; the speed of the output shaft of the transmission device is zero; the speed of the input shaft of the transmission device is zero.

[0011] According to an optional embodiment of the present invention, the detection process also needs to meet at least one of the following conditions before it is allowed to be executed: the lubricating oil temperature in the transmission device is within a predetermined temperature range; the distance detection result indicates that the transmission device is in good health. The most recent detection process meets the predetermined interval condition.

[0012] According to an optional embodiment of the present invention, the time taken for the motor speed to increase from zero to a target speed and the output torque required for the motor to maintain the target speed are detected, and the state change characteristics of the motor are detected by comparing the output torque with a predetermined torque threshold, wherein if the output torque is greater than the predetermined torque threshold, at least the detection result is calibrated as being in suspicious health condition.

[0013] According to a second aspect of the present invention, a system for monitoring the health status of a transmission device of an electric drive axle assembly of a vehicle is provided, the system comprising: a detection device for detecting the state change characteristics of the motor when the transmission device is only coupled to the motor transmission; and a control device communicatively connected to the detection device, wherein the system is configured to be able to execute the method according to any of the above embodiments.

[0014] According to a third aspect of the present invention, a computer program product, in particular a computer-readable storage medium, is provided, which includes or stores computer program instructions, and when the computer program instructions are executed by a processor, the method according to any of the above embodiments can be executed.

[0015] According to some exemplary embodiments of the present invention, lower cost and more reliable detection results can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be described in more detail below with reference to the accompanying drawings in combination with exemplary embodiments, so that the principles, features and advantages of the present invention can be better understood. The accompanying drawings include:

[0017] Figure 1 A perspective view schematically shows an electric drive axle assembly of a vehicle, in particular an electric commercial vehicle, connected to a wheel according to an exemplary embodiment of the present invention.

[0018] Figure 2 A flow chart of a method for monitoring the health of a transmission device of an electric drive axle assembly of a vehicle according to an exemplary embodiment of the present invention is shown.

[0019] Figure 3 A functional block diagram of a system for monitoring the health status of a transmission device of an electric drive axle assembly of a vehicle according to an exemplary embodiment of the present invention is shown.

[0020] Reference numerals list

[0021] 1 Electric drive axle assembly

[0022] 11 Motor

[0023] 12 Transmission

[0024] 2 wheels

[0025] 3 Systems

[0026] 31. Detection device

[0027] 32 Control Devices DETAILED DESCRIPTION

[0028] In order to make the technical problems, technical solutions and beneficial technical effects to be solved by the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and multiple exemplary embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the scope of protection of the present invention.

[0029] Figure 1A perspective view schematically shows an electric drive axle assembly of a vehicle, in particular an electric commercial vehicle, connected to a wheel according to an exemplary embodiment of the present invention.

[0030] First of all, it should be pointed out that the "electric drive axle assembly" refers to all related structures that use an electric motor as a driving source and transmit power to the wheels through a transmission device. In order to shorten the transmission path, improve transmission efficiency, and compact space layout, the current electric drive axle has a shorter transmission path than traditional vehicles, especially fuel vehicles, and even directly arranges the motor and the transmission device, especially integrates them on the axle or constitutes a part of the axle. Those skilled in the art can understand that the integrated layout is very advantageous from the perspective of assembly, cost, and reliability. The electric drive axle may take various forms, but no matter which method, as long as the concept of the present invention can be applied, it should be considered to be covered by the present invention.

[0031] like Figure 1 As shown, the electric drive axle assembly 1 includes a motor 11 and a transmission device 12 that is transmission-coupled with the motor 11 and receives power from the motor 11, and the transmission device 12 is transmission-connected to the wheel 2 through other components (not shown for simplicity) or directly. When the wheel 2 does not need to be driven, the transmission device 12 can be disconnected from the wheel 2, so that, in this case, even if the output shaft of the transmission device 12 is still rotating, the power will not be transmitted to the wheel 2. This can be achieved, for example, by a clutch (not shown).

[0032] The transmission 12 is in particular a gear transmission, such as a gear box, which is equipped with corresponding bearings and, of course, may also have other auxiliary components or substances, such as lubricating oil.

[0033] According to a first aspect of the present invention, Figure 2 As shown, a method for monitoring the health status of a transmission device 12 of an electric drive axle assembly 1 of a vehicle is provided, and the method includes at least the following detection process: step S1, making the motor 11 rotate for at least a period of time when the transmission device 12 is only coupled to the motor 11; step S2, detecting the state change characteristics of the motor 11; and step S3, monitoring the health status of the transmission device 12 based on the state change characteristics.

[0034] Those skilled in the art can understand that when the vehicle is running normally, the transmission device 12 establishes a transmission coupling between the motor 11 and the wheel 2. Therefore, "when the transmission device 12 is only in a transmission coupling state with the motor 11" means that the transmission device 12 is disconnected from the power transmission to the wheel 2 at this time, and the state change of the transmission device 12 is theoretically only affected by its own characteristics and the state change of the motor 11 with which it is transmission coupled. For a specific healthy transmission device 12, it is specially designed accordingly, and its own characteristics are relatively stable or predictable, or should be kept within a normal range. However, when the transmission device 12 is in poor health, especially when a failure occurs, its own characteristics will change.

[0035] The transmission device 12 transmits the power generated by the motor 11 to the wheel 2 in a desired manner, so theoretically, the resistance of the transmission device 12 cannot be too large, otherwise it will cause energy waste and generate more heat that needs to be discharged. To this end, according to one embodiment of the present invention, the health status of the transmission device 12 can be monitored by the change of its resistance characteristics, because when the transmission device 12 has health problems, it often means that the resistance increases. Of course, in extreme cases, for example, for a certain gear transmission mechanism, if there is a meshing failure between two gears in the transmission device 12, the resistance may also decrease. This situation is also a concern for the health status monitoring of the transmission device 12. The present invention can also monitor this fault through the change of the resistance characteristics of the transmission device 12.

[0036] Since the transmission device 12 is only transmission-coupled with the motor 11 during detection, changes in the resistance characteristics of the transmission device 12 will also affect the state changes of the motor 11, so that the health of the transmission device 12 can be monitored by detecting the state change characteristics of the motor 11 and based on the state change characteristics. It can be understood that monitoring the health of the transmission device 12 by means of the state change of the motor 11 through transmission coupling involves the exploration of the inherent characteristics of the transmission device 12, and is therefore less affected by external factors such as vibration.

[0037] As described above, the health status monitoring of the transmission device 12 is carried out when the transmission device 12 is only coupled to the motor 11. The purpose is to eliminate the situation where the resistance of the transmission device 12 itself cannot be determined due to different vehicle states (such as different load conditions). Therefore, this detection process cannot be carried out at any time, and it is necessary to find a suitable time.

[0038] The transmission device 12 is only coupled to the motor 11 in a transmission manner, which often means that the vehicle is in neutral, and neutral usually corresponds to parking, at which time the speed of the vehicle is zero. Of course, there is also a situation of neutral sliding.

[0039] Those skilled in the art can understand that the state change of the motor 11 can be either decelerating from the rotation state only under the resistance of the transmission device 12, or even decelerating to zero (this can correspond to the situation that the vehicle is driving in neutral gear, and the motor 11 does not receive power from the outside), or it can be that the motor 11 is powered to make the motor 11 rotate from zero speed to overcome the resistance of the transmission device 12 for a period of time (this can correspond to the situation that the vehicle is completely parked and the health status detection is performed after the motor 11 has stopped rotating). Although it may be very advantageous to detect the state change characteristics of the motor 11 using the parking time of the vehicle, the control strategies between different vehicles may be different, and the present invention does not limit this. As long as the state change characteristics of the motor 11 can reflect the deviation of the characteristics of the transmission device 12 itself, thereby monitoring the health status of the transmission device 12, any suitable time is fine, and even such a time can be specially created to monitor the health status of the transmission device 12. For example, during the parking period of the vehicle after the vehicle is shut down (turned off), the vehicle controller, for example, actively starts the motor 11 from the zero speed state and accelerates it to a certain rotation state according to the preset program arrangement, and then performs the health status detection according to the state change characteristics of the motor 11 during this period.

[0040] For better explanation, the relationship between the output torque T and the rotation speed V of the motor 11 can be qualitatively described by formula (1):

[0041] V=f(T) (1)

[0042] It can be understood qualitatively that, under the condition of a certain resistance, the output torque T of the motor 11 needs to overcome the resistance of the transmission device 12 to ensure that the speed V does not decrease. Conversely, in order to keep the motor 11 at a certain speed, the motor 11 needs to have a certain output torque, which is related to the resistance of the transmission device 12. In particular, if there is a problem with the health of the transmission device 12 and the resistance applied to the motor 11 increases, the transmission device 12 will appear to be more "heavy", and the motor 11 needs to have a larger output torque to bring the more "heavy" transmission device 12 to move. This provides us with the possibility of detecting the health of the transmission device 12. If the motor 11 was rotating before, in the case of no power supply or insufficient power supply, the speed of the motor 11 will be brought down by the transmission device 12. If the resistance is smaller, the speed will decrease more slowly, and if the resistance is larger, the speed will decrease faster.

[0043] Those skilled in the art will appreciate that such an association or correspondence may be established or expressed in a variety of ways, and the present invention is not limited thereto. Regardless of how it is changed, in principle, the health of the transmission device 12 may be monitored by determining whether the state change characteristic of the motor 11 deviates from a predetermined characteristic threshold or characteristic threshold range.

[0044] It can also be seen from the above description that only some parameters of the motor 11 (such as speed and output torque) and other possible parameters that can be obtained or provided by the vehicle itself (if necessary) are needed to monitor the health status of the transmission device 12 through calculation. These parameters are conventional parameters of the motor 11 or parameters that can be obtained or provided by the vehicle itself. Therefore, there is no need to arrange new hardware during implementation, which greatly reduces the cost and complexity of the structure. Moreover, as mentioned above, the monitoring results are not affected by external factors such as vibration and have high reliability.

[0045] It is mentioned above that the detection can be performed when the vehicle is parked. "Parking" may refer to a state where the vehicle is in neutral and not moving, at which time the transmission device 12 is disengaged from the wheel 2 and is only coupled to the motor 11. During the detection, the motor 11 may be in a stopped state or may still rotate due to inertia. At this time, since the vehicle is in neutral, the motor 11 no longer consumes electrical energy for driving.

[0046] According to an exemplary embodiment of the present invention, the detection process is also required to meet at least one of the following conditions before it is allowed to be executed: 1) the speed of the vehicle is zero; 2) the speed of the output shaft of the transmission device 12 is zero; 3) the speed of the input shaft of the transmission device 12 is zero. Preferably, the detection process is allowed to be executed only when all three conditions are met.

[0047] The speed of the input shaft and the output shaft of the transmission device 12 are both zero, which means that the transmission device 12 is in a non-operating state (static) and the motor 11 is also in a stopped state, so that a special health status detection can be performed from this point of view. This can improve the reliability and accuracy of the detection to a certain extent without affecting the normal driving of the vehicle.

[0048] The transmission device 12 (especially the gear transmission mechanism) requires lubricating oil to work, and the viscosity of the lubricating oil is closely related to the temperature of the lubricating oil, and the viscosity directly affects the resistance generated by the transmission device 12 to the motor 11. Generally, the lower the temperature, the greater the viscosity of the lubricating oil, and the greater the resistance generated by the transmission device 12 to the motor 11. Therefore, if the temperature of the lubricating oil is not taken into account, misjudgment may result. To this end, according to an exemplary embodiment of the present invention, the detection process also requires that the temperature of the lubricating oil in the transmission device 12 is within a predetermined temperature range before it is allowed to be executed.

[0049] The temperature of the lubricating oil can be measured by an existing temperature sensor, without the need to arrange additional sensors. Of course, those skilled in the art will understand that whether the detection process is performed may not simply depend on the temperature of the lubricating oil, but the detection process is allowed to be performed regardless of the temperature of the lubricating oil as long as other conditions are met, and the judgment condition corresponding to the temperature needs to be selected at this time. In other words, different temperatures correspond to different judgment conditions, thereby providing more possibilities for the timing selection of the detection process.

[0050] The health of the transmission 12 usually changes gradually, so if the test has just been performed recently and the test results show that the health of the transmission 12 is good, it may not be necessary to perform the test too frequently. To this end, according to an exemplary embodiment of the present invention, the test process also needs to meet a predetermined interval condition from the most recent test process before it is allowed to be executed.

[0051] The predetermined interval condition may be expressed in a variety of ways depending on the specific situation. For example, the predetermined interval condition may include at least one of the following: 1) the time interval from the last detection process is greater than the predetermined time interval; 2) the cumulative time length of the transmission device 12 working since the last detection process is greater than the predetermined time length; 3) the distance traveled by the vehicle since the last detection process is greater than the predetermined distance; 4) the integral of the output torque of the motor 11 over time since the last detection process is greater than the predetermined value.

[0052] For the predetermined interval condition 1), it is relatively simple, but the vehicle may be stopped for a period of time, which may lead to redundant detection. For the predetermined interval condition 2), it can better reflect the actual operation of the transmission device 12 and is more reliable. For the predetermined interval condition 3), the actual operation of the transmission device 12 can also be reflected by the driving distance of the vehicle. For the predetermined interval condition 4), not only the working time of the transmission device 12 is considered, but also the workload, which will affect the health of the transmission device 12.

[0053] According to an exemplary embodiment of the present invention, the detection process is performed automatically. In other words, the vehicle self-judges and decides when to perform the detection. Thus, no human intervention is required. However, when the detection result indicates that the health of the transmission device 12 is not good, an alarm message is output to the user so that the user can understand and deal with it in time.

[0054] In addition, in order to avoid false detection, an opportunity can be found to perform a second detection as soon as possible when the health of the transmission device 12 is initially detected to be poor. If multiple detections show that the health of the transmission device 12 is poor, it can be considered that there is indeed a problem with the health of the transmission device 12.

[0055] Preferably, the detection process is performed after the vehicle is shut down and before the vehicle controller goes to sleep. "Vehicle shutdown" means turning off the vehicle by pressing the vehicle's start button, which usually happens when the driver parks the vehicle and is about to leave. After pressing the start button, the vehicle controller, such as the ECU, will enter a sleep state for a short period of time, and this period of time is a good opportunity to perform detection.

[0056] It can be seen from the above description that, when the resistance of the transmission device 12 is constant, there is a certain correlation between the speed change of the motor 11, the time corresponding to the speed change, and the output torque of the motor 11. For example, when the motor 11 is started from a stopped state, the greater the resistance of the transmission device 12, the longer the time required for the motor 11 to reach the corresponding speed under the same output torque, or the motor 11 cannot reach the corresponding speed at all, and the speed change is naturally slow. Therefore, according to an exemplary embodiment of the present invention, the state change characteristics of the motor 11 are characterized by at least two of the relationship among the speed change of the motor 11, the time corresponding to the speed change, and the output torque of the motor 11.

[0057] During the detection process, it may be necessary to terminate the detection at any time. When the vehicle meets the detection termination conditions, the detection process is terminated to avoid inaccurate detection or damage to the vehicle or to give priority to other vehicle usage requirements. For example, when the vehicle is switched from neutral to other gears, it means that the transmission device 12 is coupled to the wheels 2, so it is no longer suitable for health status detection, and the detection process needs to be terminated.

[0058] According to an exemplary embodiment of the present invention, the detection termination condition may include: the vehicle is switched from neutral to other gears, the speed of the vehicle is non-zero, and the speed of the output shaft of the transmission 12 is non-zero.

[0059] Those skilled in the art will appreciate that, if other prerequisites are set for the execution of the detection process as described above, the detection termination condition also includes: these prerequisites are not met.

[0060] With the development of big data technology and artificial intelligence, it is also possible to consider building a health diagnosis model (for example, an artificial neural network) for the transmission device 12. The health diagnosis model can be built or trained based on software simulation, experiments or historical data. This can greatly improve the accuracy of diagnosis and also enable the detection process to be performed under more conditions.

[0061] In the transmission device 12, bearings and / or gears are more likely to be damaged, and damage to bearings and / or gears will directly lead to changes in resistance. Therefore, the above method can be mainly used to detect the health of bearings and / or gears.

[0062] According to a second aspect of the present invention, Figure 3 As shown, a system 3 for monitoring the health of a transmission device 12 of an electric drive axle assembly 1 of a vehicle is provided, wherein the system 3 comprises: a detection device 31 for detecting the state change characteristics of the motor 11 when the transmission device 12 is only coupled to the motor 11 in a driving manner; and a detection device 31 in communication with the detection device 31 (e.g. Figure 3 A control device 32 (as shown by the double-headed arrow in ), wherein the system 3 is configured to be able to execute a method according to any of the above embodiments.

[0063] According to a third aspect of the present invention, a computer program product, in particular a computer-readable storage medium, is provided, which includes or stores computer program instructions, and when the computer program instructions are executed by a processor, the method according to any of the above embodiments can be executed.

[0064] Although specific embodiments of the present invention are described in detail herein, they are provided for the purpose of explanation only and should not be considered to limit the scope of the present invention. Various substitutions, changes and modifications may be conceived without departing from the spirit and scope of the present invention.

Claims

1. A method for monitoring the health of a transmission device (12) of an electric drive axle assembly (1) of a vehicle, wherein: The electric drive axle assembly (1) further comprises an electric motor (11) for transmission coupling with the transmission device (12), and the method comprises at least the following detection process: The motor (11) is kept in a rotating state for at least a period of time in a state where the transmission device (12) is only transmission-coupled with the motor (11); Detecting the state change characteristics of the motor (11); and The health status of the transmission device (12) is monitored based on the state change characteristics.

2. The method according to claim 1, wherein: The health status of the transmission device (12) is monitored by comparing the state change characteristics of the motor (11) with a predetermined characteristic threshold or a characteristic threshold range.

3. The method according to claim 1, wherein: By placing the vehicle in a neutral state, the transmission device (12) is placed in a state of transmission coupling only with the motor (11).

4. The method according to any one of claims 1 to 3, wherein: The detection process is also allowed to be executed if at least one of the following conditions is met: The speed of the vehicle is zero; The speed of the output shaft of the transmission device (12) is zero; The speed of the input shaft of the transmission (12) is zero.

5. The method according to any one of claims 1 to 4, wherein: The detection process is also allowed to be executed if at least one of the following conditions is met: The lubricating oil temperature in the transmission device (12) is within a predetermined temperature range; The distance detection result indicates that the health of the transmission device (12) is good and the most recent detection process meets the predetermined interval condition.

6. The method according to any one of claims 1 to 5, wherein: The detection process is performed automatically; and / or outputting an alarm message when the detection result indicates that there is a problem with the health condition of the transmission device (12); and / or The method is used to monitor the health of bearings and / or gears in the transmission (12).

7. The method according to any one of claims 1 to 6, wherein: The detection process is performed after the vehicle is turned off and before the controller of the vehicle enters sleep.

8. The method according to claim 5, wherein: The predetermined interval condition includes at least one of the following: The time interval from the most recent detection process is greater than a predetermined time interval; The cumulative operation time of the transmission device (12) since the most recent detection process is greater than a predetermined time; The distance traveled by the vehicle since the most recent detection process is greater than a predetermined distance; The integral of the output torque of the motor (11) over time since the most recent detection process is greater than a predetermined value.

9. The method according to any one of claims 1 to 8, wherein: The state change characteristics of the motor (11) are characterized by at least two of the relationship among the speed change of the motor (11), the time corresponding to the speed change, and the output torque of the motor (11).

10. The method according to claim 9, wherein: The time taken for the rotation speed of the motor (11) to change from zero to a target rotation speed and the output torque required for the motor (11) to maintain the target rotation speed are detected, and the state change characteristics of the motor (11) are detected by comparing the output torque with a predetermined torque threshold, wherein if the output torque is greater than the predetermined torque threshold, at least the detection result is marked as suspicious health status.

11. The method according to any one of claims 1 to 10, wherein: When a detection termination condition is met, the detection process is terminated, wherein the detection termination condition at least includes: the vehicle is switched from neutral gear to another gear.

12. A system (3) for monitoring the health of a transmission device (12) of an electric drive axle assembly (1) of a vehicle, the system (3) comprising: A detection device (31) for detecting state change characteristics of the motor (11) when the transmission device (12) is only transmission-coupled with the motor (11); and a control device (32) communicatively connected to the detection device (31), The system (3) is configured to be able to execute the method according to any one of claims 1-11.

13. A computer program product, in particular a computer-readable storage medium, comprising or storing computer program instructions, which are capable of executing the method according to any one of claims 1 to 11 when the computer program instructions are executed by a processor.

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