Abnormal noise detection system

Abstract

To determine from which of front and rear driving devices in an all-wheel drive vehicle a noise is arising.SOLUTION: When it is determined that a noise is caused by an electric motor or a gear during traveling, a time history of torque changes of each of front and rear electric motors caused by acceleration / deceleration traveling is compared with a time history of sound pressure changes of the noise. Then, it is determined that the noise is arising from a driving device of a front wheel driving device or a rear wheel driving device, that is determined that the time history of the torque changes and the time history of the sound pressure changes coincide with each other in terms of increase and decrease times. Thus, even in an all-wheel drive vehicle in which the front and rear electric motors have the same number of poles and the front and rear power transmission devices have at least partially the same configuration, it is possible to identify the source of the noise by using the torque of the electric motor that changes differently between the front and rear sides accompanying the acceleration / deceleration traveling. Therefore, it is possible to determine from which of the front and rear driving devices in the all-wheel drive vehicle the noise is arising.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an abnormal sound detection system. [Background technology]

[0002] There are well-known abnormal sound detection systems used to detect abnormal sounds in vehicles, such as the sound and vibration analyzer described in Patent Document 1. Patent Document 1 discloses a method for identifying the gear causing the abnormal sound by analyzing the frequency of the abnormal sound and determining the order specific to each gear, which is determined by the number of teeth of each gear in a power transmission device, from the frequency-analyzed abnormal sound. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-98984 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, examples of vehicles for which abnormal noise may be detected include all-wheel drive vehicles equipped with front-wheel drive units and rear-wheel drive units, each including front and rear electric motors and front and rear power transmission units. In such all-wheel drive vehicles, the front and rear electric motors may have the same number of poles and at least some of the components of the front and rear power transmission units may be identical to facilitate commonality of parts. In such cases, the frequency of abnormal noise generated relative to vehicle speed may be the same for the front and rear. Therefore, even if it is possible to determine that the cause of the abnormal noise is a gear or an electric motor in the power transmission unit based on the results of order calculations, it is difficult to determine which of the front-wheel drive unit or the rear-wheel drive unit is generating the abnormal noise.

[0005] The present invention has been made in light of the above circumstances, and its object is to provide an abnormal noise detection system that can determine whether an abnormal noise is coming from the front or rear drive unit of an all-wheel drive vehicle. [Means for solving the problem]

[0006] The gist of the first invention is that (a) an abnormal noise detection system used to detect abnormal noise in an all-wheel drive vehicle equipped with a front-wheel drive unit and a rear-wheel drive unit, each including an electric motor with the same number of poles at the front and rear and a power transmission unit with at least a portion of the configuration being the same at the front and rear, (b) when it is determined that the abnormal noise is caused by the electric motor or a gear in the power transmission unit while the vehicle is traveling, (c) it compares the time history of torque changes in the front and rear electric motors that occur as the vehicle accelerates or decelerates with the time history of sound pressure changes of the abnormal noise, and (d) it determines that the abnormal noise is coming from either the front-wheel drive unit or the rear-wheel drive unit, whichever of the drive units it determines has the same increase and decrease times in the time history of the torque changes and the time history of the sound pressure changes. [Effects of the Invention]

[0007] According to the first aspect of the present invention, when it is determined that an abnormal noise is caused by an electric motor or gear during driving, the time history of torque changes in the front and rear electric motors that occur as the vehicle accelerates or decelerates is compared with the time history of sound pressure changes of the abnormal noise. Then, it is determined that the abnormal noise is coming from either the front-wheel drive unit or the rear-wheel drive unit, whichever is determined to have the same increase or decrease times in the time history of torque changes and the time history of sound pressure changes. This makes it possible to identify the source of the abnormal noise by using the torque of the front and rear electric motors, which changes differently as the vehicle accelerates or decelerates, even in an all-wheel drive vehicle in which the front and rear electric motors have the same number of poles and the front and rear power transmissions have at least some of the same configuration. This makes it possible to determine whether the abnormal noise is coming from the front or rear drive unit in an all-wheel drive vehicle. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a schematic configuration of an abnormal sound detection device to which the present invention is applied, and a schematic configuration of a vehicle in which an abnormal sound is detected by the abnormal sound detection device; [Figure 2] FIG. 2 is a diagram illustrating an abnormal sound diagnosis performed by the abnormal sound detection device. [Figure 3] 1A and 1B are diagrams illustrating the mechanism by which MG noise and gear noise occur. [Figure 4] 1 is a flowchart illustrating a main part of the control operation of the abnormal noise detection system, specifically, a flowchart illustrating the control operation for determining whether an abnormal noise is coming from the front or rear drive unit of a vehicle. [Figure 5] This is a flowchart explaining the main parts of the control operation of the abnormal sound detection system, specifically the control operation for determining whether the abnormal sound is coming from the front or rear drive unit of the vehicle, and is executed when the sound producing unit cannot be identified even when the flowchart of Figure 4 is executed. [Figure 6] FIG. 10 is a diagram illustrating an example of another embodiment of the abnormal sound detection system. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Example]

[0010] FIG. 1 is a diagram illustrating the schematic configuration of an abnormal sound detection device 80 as an abnormal sound detection system to which the present invention is applied, and the schematic configuration of a vehicle 10 for which abnormal sounds are detected by the abnormal sound detection device 80. The vehicle 10 has left and right front wheels 12, a front-wheel drive unit 14 that drives the front wheels 12, left and right rear wheels 16, and a rear-wheel drive unit 18 that drives the rear wheels 16, which are spaced apart from one another. The vehicle 10 is an all-wheel-drive vehicle that can adjust the distribution of drive torque between the front wheels 12 and the rear wheels 16. The vehicle 10 has four wheels, including two front wheels 12 and two rear wheels 16, and is therefore also a four-wheel-drive vehicle. In this embodiment, all-wheel drive (AWD) and four-wheel drive (4WD) are synonymous. The vehicle 10 can also be driven in two-wheel-drive (2WD) control, in which drive torque is distributed to only one of the front wheels 12 and the rear wheels 16.

[0011] The front-wheel drive unit 14 has only a front-wheel electric motor 20 as a power source, and also has a front-wheel power transmission unit 22 that changes the speed of the rotation of the front-wheel electric motor 20 and transmits it to the front wheels 12. The front-wheel electric motor 20 is connected to a battery 26 via a front-wheel PCU (Power Control Unit) 24 that has an inverter or the like. The rear-wheel drive unit 18 has only a rear-wheel electric motor 28 as a power source, and also has a rear-wheel power transmission unit 30 that changes the speed of the rotation of the rear-wheel electric motor 28 and transmits it to the rear wheels 16. The rear-wheel electric motor 28 is connected to the battery 26 via a rear-wheel PCU 32 that has an inverter or the like. The front-wheel electric motor 20 and the rear-wheel electric motor 28 are both so-called motor generators that function as generators that generate electricity when rotated. The vehicle 10 is a front-wheel independent-drive electric vehicle (BEV) that has only a battery 26 as a power source. In this embodiment, when there is no particular distinction between the front-wheel drive device 14 and the rear-wheel drive device 18, they are referred to as drive device PU. When there is no particular distinction between the front-wheel electric motor 20 and the rear-wheel electric motor 28, they are referred to as electric motor MG. When there is no particular distinction between the front-wheel power transmission device 22 and the rear-wheel power transmission device 30, they are referred to as power transmission device PT.

[0012] The vehicle 10 is equipped with an electronic control unit 50 as a controller including control devices for the vehicle 10 related to various controls such as torque distribution control of the drive unit PU. The electronic control unit 50 is configured to include a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, etc. The CPU executes various controls of the vehicle 10 by performing signal processing according to programs stored in the ROM in advance while utilizing the temporary storage function of the RAM.

[0013] The electronic control unit 50 is supplied with various signals (e.g., front MG rotational speed Nmf, rear MG rotational speed Nmr, front wheel rotational speeds Nwfl, Nwfr, rear wheel rotational speeds Nwrl, Nwrr, accelerator opening θacc, brake-on signal Bon, longitudinal acceleration Gx, lateral acceleration Gy, yaw rate Ryaw, etc.) based on detection values ​​from various sensors (front MG rotational speed sensor 60, rear MG rotational speed sensor 62, each wheel speed sensor 64, accelerator opening sensor 66, brake switch 68, G sensor 70, yaw rate sensor 72, etc.) provided on the vehicle 10.

[0014] The front MG rotation speed Nmf is the rotation speed of the front wheel electric motor 20. The rear MG rotation speed Nmr is the rotation speed of the rear wheel electric motor 28. The front wheel rotation speeds Nwfl and Nwfr are the rotation speeds of the left and right front wheels 12. The rear wheel rotation speeds Nwrl and Nwrr are the rotation speeds of the left and right rear wheels 16. The accelerator opening θacc is a signal that indicates the magnitude of the driver's acceleration operation, and is the amount of accelerator operation by the driver. The brake-on signal Bon is a signal that indicates the state in which the brake pedal for activating the wheel brakes is being operated by the driver. The longitudinal acceleration Gx is the acceleration in the longitudinal direction of the vehicle 10. The lateral acceleration Gy is the acceleration in the lateral direction of the vehicle 10. The yaw rate Ryaw is the rotational angular velocity of the vehicle 10 around the vertical axis. Based on the front wheel rotation speeds Nwfl, Nwfr and the rear wheel rotation speeds Nwrl, Nwrr, the vehicle speed V is calculated from, for example, their average value, or the average value of the front wheel rotation speeds Nwfl, Nwfr, or the average value of the rear wheel rotation speeds Nwrl, Nwrr.

[0015] The electronic control device 50 outputs various command signals (for example, a front MG control command signal Smf, a rear MG control command signal Smr, etc.) to each device provided in the vehicle 10 (for example, a front wheel PCU 24, a rear wheel PCU 32, etc.).

[0016] The front MG control command signal Smf is a torque command value for controlling, for example, a front MG torque Tmf, which is the torque of the front wheel electric motor 20. The rear MG control command signal Smr is a torque command value for controlling, for example, a rear MG torque Tmr, which is the torque of the rear wheel electric motor 28.

[0017] The electronic control unit 50 calculates the drive demand Qrdem imposed on the vehicle 10 by the driver, for example, by applying the accelerator opening θacc and the vehicle speed V to a drive demand map. The drive demand map is a relationship for calculating the drive demand Qrdem that is determined experimentally or by design and stored in advance, i.e., a predetermined relationship. The drive demand Qrdem may be, for example, a required drive torque Trdem [Nm] or a required drive force Frdem [N] for the wheels (front wheels 12, rear wheels 16). The required drive torque Trdem is the sum of a required front wheel drive torque Trfdem for the front wheels 12 and a required rear wheel drive torque Trrdem for the rear wheels 16.

[0018] The electronic control unit 50 sets the front and rear wheel torque distribution ratio γfr by applying multiple driving force-related values, such as the accelerator opening θacc, vehicle speed V, longitudinal acceleration Gx, and yaw rate Ryaw, to a torque distribution ratio map. The torque distribution ratio map is a predetermined relationship for determining the torque distribution ratio γfr. The electronic control unit 50 calculates the required front wheel drive torque Trfdem and the required rear wheel drive torque Trrdem based on, for example, the required drive torque Trdem and the torque distribution ratio γfr. The electronic control unit 50 outputs a front MG control command signal Smf for controlling the front wheel electric motor 20 to realize the required front wheel drive torque Trfdem. The electronic control unit 50 also outputs a rear MG control command signal Smr for controlling the rear wheel electric motor 28 to realize the required rear wheel drive torque Trrdem.

[0019] The abnormal sound detector 80 constitutes an abnormal sound detector system used to detect abnormal sounds in the vehicle 10, and is a separate device from the vehicle 10. The abnormal sound detector 80 is, for example, a mobile terminal such as a personal computer, tablet, or smartphone. The abnormal sound detector 80 is used, for example, to respond to a user of the vehicle 10 when an abnormal sound occurs, or by workers at a vehicle dealership, repair shop, or the like during a reproduction test in which the vehicle 10 is driven on a road or on a test bench to reproduce an abnormal sound.

[0020] The abnormal sound discrimination device 80 includes, for example, a CPU, RAM, ROM, an input / output interface, a microphone, a speaker, etc., and diagnoses abnormal sounds generated in the vehicle 10 by processing data, etc., in accordance with a pre-installed abnormal sound diagnosis application (program). The microphone and speaker may be provided separately from the abnormal sound discrimination device 80 and connected to the abnormal sound discrimination device 80 wirelessly or via a wire. In this case, the abnormal sound discrimination device 80, together with a microphone, etc. (not shown), constitutes an abnormal sound discrimination system.

[0021] The abnormal sound detection device 80 includes a display unit 82, a communication module 84, an abnormal sound diagnosis unit 86, etc. The display unit 82 includes, for example, a touch panel type liquid crystal or organic electroluminescence (EL) display. The communication module 84 exchanges various information with the electronic control unit 50 of the vehicle 10 via, for example, short-range wireless communication or a cable.

[0022] FIG. 2 is a diagram illustrating the abnormal sound diagnosis performed by the abnormal sound discrimination device 80. In FIG. 2, the abnormal sound diagnosis unit 86 acquires vehicle model information (see "Frame No." in FIG. 2) and medical interview information (see "Inquiry Items" in FIG. 2) via the display unit 82 and the communication module 84. The vehicle model information is information for identifying the vehicle model of the vehicle 10, such as the chassis number or vehicle identification number. The medical interview information is information indicating the condition of the vehicle 10 when an abnormal sound occurs, provided by the user of the vehicle 10, for example. The medical interview information includes, for example, the location where the abnormal sound occurs, the driving conditions when the abnormal sound occurs, onomatopoeia corresponding to the abnormal sound, such as rattle, rattle, or high-pitched squeal, the road surface conditions when the abnormal sound occurs, and the frequency of occurrence. The abnormal sound diagnosis unit 86 narrows down the abnormal sounds based on the vehicle model information and medical interview information, and outputs the results to the display unit 82.

[0023] Based on the results of narrowing down the abnormal noises based on the vehicle model information and medical interview information, a reproduction test is performed to reproduce the driving conditions under which the abnormal noise occurred. When the reproduction test is performed, the abnormal noise discrimination device 80 is brought into the passenger compartment of the vehicle 10, for example (see the abnormal noise discrimination device 80 indicated by the dashed line in FIG. 1). When the reproduction test is performed, the abnormal noise diagnosis unit 86 acquires sound data via a microphone and vehicle data via a communication module 84. The sound data is, for example, time-axis data of sound, i.e., sound pressure (equivalent to the time history of sound pressure changes). The vehicle data is, for example, vehicle state information indicating the state of the vehicle 10 synchronized with the time-axis data of sound pressure. The vehicle state information is time-axis data such as vehicle speed V, accelerator opening θacc corresponding to accelerator operation, and brake-on signal Bon corresponding to brake operation. Instead of vehicle speed V, front MG rotation speed Nmf and rear MG rotation speed Nmr, or front wheel rotation speeds Nwfl and Nwfr and rear wheel rotation speeds Nwrl and Nwrr may be used.

[0024] The abnormal sound diagnosis unit 86 performs frequency analysis on the time-axis data of sound pressure using a fast Fourier transform (=FFT). The abnormal sound diagnosis unit 86 identifies the frequency range in which the abnormal sound is occurring and the time range in which the abnormal sound is occurring based on the results of the frequency analysis of the time-axis data of sound pressure, the medical interview information, the vehicle data, etc. Therefore, the time-axis data of sound pressure includes the time history of changes in the sound pressure of the abnormal sound. The results of the frequency analysis of the time-axis data of sound pressure, etc., are output to the display unit 82, and the operator may select the frequency range in which the abnormal sound is occurring and the time range in which the abnormal sound is occurring.

[0025] The abnormal sound diagnosis unit 86 identifies the cause of the abnormal sound and the part that is the source of the abnormal sound based on the time axis data of sound pressure, the frequency range in which the abnormal sound is occurring, the time range in which the abnormal sound is occurring, vehicle data, etc.

[0026] When the abnormal sound diagnosis unit 86 identifies the cause of an abnormal sound, for example, a learning model 88 (see FIG. 1) based on machine learning is used (see "Abnormal sound determination by AI" in FIG. 2). The abnormal sound diagnosis unit 86 applies sound data (for example, the time history of changes in the sound pressure of the abnormal sound), the frequency range in which the abnormal sound occurs, the time range in which the abnormal sound occurs, vehicle data, and the like to the learning model 88 to identify the cause of the abnormal sound and the part that is the source of the abnormal sound. The learning model 88 is a pre-determined trained model that indicates the relationship between the time history of changes in the sound pressure of the abnormal sound and the cause of the abnormal sound. The learning model 88 is realized by supervised learning based on machine learning, using the sound data and the cause of the abnormal sound as training data, i.e., training signals.

[0027] The learning model 88 is a neural network based on sound data, the frequency range in which the abnormal noise occurs, the time range in which the abnormal noise occurs, vehicle data, etc. The learning model 88 is configured by modeling biological nerve cell groups using computer program software. The learning model 88 has a multi-layer structure made up of an input layer made up of multiple nerve cell elements (neurons), an intermediate layer made up of multiple nerve cell elements, and an output layer made up of multiple nerve cell elements. The intermediate layer may also have a multi-layer structure. In the learning model 88, for example, sound data, the frequency range in which the abnormal noise occurs, the time range in which the abnormal noise occurs, and vehicle data are provided as teacher signals for the input layer. In the learning model 88, the abnormal noise diagnosis result, i.e., the cause of the abnormal noise and the part that is the source of the abnormal noise, is provided as teacher signals for the output layer.

[0028] The learning model 88 identifies the cause of the abnormal noise and the part that is the source of the noise, thereby determining whether the abnormal noise is caused by the electric motor MG or the gear G in the power transmission device PT. The gear G in the power transmission device PT is an expression used when no particular distinction is made between the gear Gf (see FIG. 1) in the front-wheel power transmission device 22 and the gear Gr (see FIG. 1) in the rear-wheel power transmission device 30. The gear G is a mechanical part that constitutes the power transmission device PT and transmits power by meshing gear teeth.

[0029] In this way, the abnormal sound diagnosis unit 86 determines whether or not an abnormal sound is caused by the electric motor MG or the gear G in the power transmission device PT while the vehicle is running by applying the time history of sound pressure changes to the learning model 88. "A noise caused by the electric motor MG or the gear G" is the same as "MG noise" which is noise from the electric motor MG or "gear noise" which is noise from the gear G.

[0030] In the vehicle 10 of this embodiment, the front-wheel drive device 14 and the rear-wheel drive device 18 are configured as the same unit. For example, the front-wheel electric motor 20 and the rear-wheel electric motor 28 have the same number of poles. Furthermore, the front-wheel power transmission device 22 and the rear-wheel power transmission device 30 have the same configuration. In other words, the vehicle 10 is equipped with the front-wheel drive device 14 and the rear-wheel drive device 18, which include electric motors MG with the same number of poles in the front and rear, and power transmission devices PT with the same configuration in the front and rear. Having the same configuration in the power transmission devices PT means that the gears G in the power transmission devices PT have the same number of teeth in the front and rear.

[0031] On the other hand, as shown in Figure 3, forcing forces (vibrations) caused by sources such as torque fluctuations in the electric motor MG and meshing vibrations of the gears G in the power transmission device PT are transmitted to the case and then propagated from the case into the air, producing MG noise (see (b) in Figure 3) and gear noise (see (a) in Figure 3), which can worsen NV (noise and vibration) performance inside the vehicle cabin during acceleration and deceleration. Torque fluctuations in the electric motor MG are caused by fluctuations in power torque and regenerative torque, for example, and generate vibrations with a frequency corresponding to the number of poles. Meshing vibrations in the gears G are caused by vibrations in the rotational direction due to gear meshing errors and axial vibrations due to helical gears, and generally generate vibrations with a frequency corresponding to the rotational speed.

[0032] However, when it is determined that an abnormal noise is caused by the electric motor MG or the gear G while the vehicle is running, it is difficult to determine whether the abnormal noise is coming from the front or rear unit because the front and rear electric motors MG have the same number of poles and the front and rear gears G have the same number of teeth.

[0033] As shown in FIG. 3, the forcing forces of MG noise and gear noise both have torque characteristics, so when the MG torque Tm, which is the torque of the electric motor MG, changes, the noise level also changes. Therefore, the abnormal sound diagnosis unit 86 compares the time history of the sound pressure change of the abnormal sound when it is determined that the abnormal sound is caused by the electric motor MG or the gear G during driving with the time history of the torque change of the electric motor MG (equivalent to the torque time axis data), and identifies the front or rear unit that exhibits a similar change as the noise source. To achieve this, the torque changes of the front and rear electric motors MG must be made different. For example, when accelerating or decelerating, a torque difference is likely to occur between the front and rear electric motors MG due to a change in the torque distribution ratio γfr between the front and rear wheels, and the torque changes of the front and rear electric motors MG are likely to be made different.

[0034] Therefore, when the abnormal sound diagnosis unit 86 determines during the reproduction test that the abnormal sound is caused by the electric motor MG or the gear G while the vehicle is running, it provides guidance to encourage the vehicle to accelerate or decelerate. For example, the abnormal sound diagnosis unit 86 outputs to the display unit 82 a message to encourage the vehicle to accelerate or decelerate.

[0035] In this way, when the abnormal sound diagnosis unit 86 determines that the abnormal sound is caused by the electric motor MG or the gear G while the vehicle is running, it compares the time history of torque changes in the front and rear electric motors MG that occur as the vehicle accelerates or decelerates with the time history of changes in sound pressure of the abnormal sound.The abnormal sound diagnosis unit 86 then determines that the abnormal sound is coming from either the front-wheel drive unit 14 or the rear-wheel drive unit 18, whichever drive unit PU is determined to have the same increase and decrease periods in the time history of torque changes in the electric motor MG and the time history of changes in sound pressure of the abnormal sound.

[0036] FIG. 4 is a flowchart explaining the main control operations of the abnormal noise detection system, specifically, the control operations for determining whether the abnormal noise is coming from the front or rear drive unit PU of the vehicle 10, and is executed, for example, during a reproduction test.

[0037] In FIG. 4, each step in the flowchart corresponds to a function of the abnormal sound diagnosis unit 86. In step S10 (hereinafter, "step" is omitted), abnormal sound diagnosis begins, and vehicle model information, medical interview information, sound data, vehicle data, and the like are acquired. Next, in S20, it is determined whether an abnormal sound reported by a user or the like while driving is determined to be MG noise or gear noise. If the determination in S20 is affirmative, in S30, a message is displayed on the display unit 82 to prompt the driver to accelerate or decelerate. Next, in S40, the time history of sound pressure changes of the abnormal sound is compared with the time history of torque changes of the front and rear electric motors MG. Next, if the user selects to end the abnormal sound diagnosis in S50, in S60, the sound generating unit (PU) of the drive unit PU that is generating the abnormal sound is identified, and this routine is terminated. If the determination in S20 is negative, the process proceeds to another flowchart for conducting another investigation.

[0038] Even when the flowchart of FIG. 4 is executed, it may not be possible to identify the sound-producing unit. In this case, the operator is asked to change the position of the abnormal sound detector 80, particularly the position of the microphone. For example, a message indicating that the position of the abnormal sound detector 80 will be changed is output to the display unit 82. After the position of the abnormal sound detector 80 has been changed, the operator is asked to perform a reproduction test similar to that before the change. The abnormal sound diagnosis unit 86 compares the sound pressure levels of the abnormal sound before and after the change of the position of the abnormal sound detector 80. If the sound pressure level is lower after the change, the abnormal sound diagnosis unit 86 determines that the abnormal sound is coming from the drive unit PU that is farther away due to the change of position. On the other hand, if the sound pressure level is higher after the change, the abnormal sound diagnosis unit 86 determines that the abnormal sound is coming from the drive unit PU that is closer due to the change of position.

[0039] The abnormal sound detection device 80 may be positioned in the front and rear seats of the vehicle 10. If the microphone position was in the front seat last time, the subject is asked to perform a reproduction test in the rear seat this time, similar to the test before the change, and if the microphone position was in the rear seat last time, the subject is asked to perform a reproduction test in the front seat this time, similar to the test before the change. The abnormal sound diagnosis unit 86 compares the sound pressure levels of abnormal sounds from the front and rear seats. If the sound pressure level is higher in the front seat, the abnormal sound diagnosis unit 86 determines that the abnormal sound is coming from the front-wheel drive unit 14. On the other hand, if the sound pressure level is higher in the rear seat, the abnormal sound diagnosis unit 86 determines that the abnormal sound is coming from the rear-wheel drive unit 18.

[0040] In this way, when the abnormal noise diagnosis unit 86 determines that an abnormal noise is caused by the electric motor MG or gear G while driving, if it is unable to determine whether the abnormal noise is coming from the front or rear drive unit PU, it determines whether the abnormal noise is coming from the front or rear drive unit PU by comparing the sound pressure of the abnormal noise after the abnormal noise measurement position has been changed with the sound pressure of the abnormal noise before the abnormal noise measurement position was changed.

[0041] FIG. 5 is a flowchart explaining the main control operations of the abnormal sound detection system, specifically, the control operations for determining whether the abnormal sound is coming from the front or rear drive unit PU of the vehicle 10, and is executed, for example, when the sound-producing unit cannot be identified even when the flowchart of FIG. 4 is executed.

[0042] In FIG. 5 , each step in the flowchart corresponds to a function of the abnormal sound diagnosis unit 86. In S110, it is determined whether the microphone position at the time of the previous abnormal sound diagnosis was in the front seat or the rear seat, based on, for example, the selection result by the operator as an example of medical interview information. If the determination in S110 is that the microphone was in the front seat, in S120 a message is displayed on the display unit 82 to prompt the operator to perform the abnormal sound diagnosis in the rear seat. Next, in S130, the sound pressure of the abnormal sound is measured in the rear seat. If the determination in S110 is that the microphone was in the rear seat, in S140 a message is displayed on the display unit 82 to prompt the operator to perform the abnormal sound diagnosis in the front seat. Next, in S150, the sound pressure of the abnormal sound is measured in the front seat. Following S130 or S150, in S160, the measurement results of the sound pressure of the abnormal sound in the front seat and the sound pressure of the abnormal sound in the rear seat are compared. Next, in S170, the sound generating unit of the front and rear drive units PU is identified based on a comparison of the measurement results, and this routine is then terminated.

[0043] As described above, according to this embodiment, when it is determined that an abnormal noise is caused by the electric motor MG or the gear G during vehicle travel, the time history of torque changes of the front and rear electric motors MG that occur with acceleration or deceleration is compared with the time history of sound pressure changes of the abnormal noise. Then, it is determined that the abnormal noise is coming from the drive unit PU of either the front-wheel drive unit 14 or the rear-wheel drive unit 18, whichever is determined to have the same increase or decrease timing between the time history of torque changes of the electric motor MG and the time history of sound pressure changes of the abnormal noise. This makes it possible to identify the source of the abnormal noise by using the MG torque Tm, which changes differently between the front and rear electric motors MG and the rear and rear power transmission units PT, even in a vehicle 10 in which the front and rear electric motors MG have the same number of poles and the front and rear power transmission units PT have the same configuration. Therefore, it is possible to determine whether the abnormal noise is coming from the front or rear drive unit PU of the vehicle 10.

[0044] Furthermore, according to this embodiment, when it is determined that the abnormal noise is caused by the electric motor MG or the gear G while the vehicle is running, guidance is given to encourage the vehicle to accelerate or decelerate. As a result, the MG torque Tm changes differently between the front and rear depending on the acceleration or deceleration of the vehicle, making it possible to identify the source of the abnormal noise.

[0045] Furthermore, according to this embodiment, it is determined whether or not an abnormal noise is caused by the electric motor MG or the gear G while the vehicle is running by applying the time history of sound pressure changes to the learning model 88. This allows an appropriate determination to be made as to whether or not the abnormal noise is MG noise or gear noise.

[0046] Furthermore, according to this embodiment, when it is determined that an abnormal noise is caused by the electric motor MG or the gear G while the vehicle is running, if it is not possible to determine whether the front or rear drive unit PU is generating the abnormal noise, the sound pressure of the abnormal noise after the measurement position has been changed is compared with the sound pressure of the abnormal noise before the measurement position has been changed, thereby determining whether the front or rear drive unit PU is generating the abnormal noise. This makes it possible to determine whether the front or rear drive unit PU in the vehicle 10 is generating the abnormal noise.

[0047] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention can also be applied to other embodiments.

[0048] For example, in the above-described embodiment, even if one of the front-wheel drive system and the rear-wheel drive system is a hybrid vehicle equipped with a known internal combustion engine (engine) in addition to an electric motor as a power source, the vehicle can be a target vehicle for abnormal noise detection by the abnormal noise detection device 80. Alternatively, if the front-wheel drive system and the rear-wheel drive system are identical in some but not all configuration, the frequency of the gear noise generated by the identical components is considered to be the same. This creates the problem of difficulty in determining whether the abnormal noise is coming from the front or rear unit, as described above. Therefore, even if a vehicle is equipped with a front-wheel drive system and a rear-wheel drive system including a power transmission system with some of the configuration identical between the front and rear, the vehicle can be a target vehicle for abnormal noise detection by the abnormal noise detection device 80. In other words, any all-wheel drive vehicle equipped with a front-wheel drive system and a rear-wheel drive system including an electric motor with the same number of poles between the front and rear and a power transmission system with at least some of the configuration identical between the front and rear can be a target vehicle for abnormal noise detection by the abnormal noise detection device of the present invention.

[0049] In the above-described embodiment, an abnormal sound discrimination system 100 may be configured with an abnormal sound discrimination device 80 and a server 90, as shown in FIG. 6 . For example, the server 90 is a device separate from the vehicle 10 and is a computer equipped with a CPU and connected to a publicly known network 200 outside the vehicle 10. The server 90 has a function of communicating with the abnormal sound discrimination device 80 via the network 200. The server 90 has, for example, the functions of the abnormal sound diagnosis unit 86, excluding the function of acquiring vehicle model information, medical interview information, sound data, and vehicle data, a function of analyzing sound data, a function of identifying the cause of the abnormal sound or the component that is the source of the abnormal sound, and a function of determining whether the abnormal sound is coming from the front or rear drive unit PU of the vehicle 10. The communication module 84 of the abnormal sound discrimination device 80 is connected to the network 200 via wireless communication R between the communication module 84 and a wireless device 210 outside the vehicle 10, for example. The communication module 84 also has a function of communicating with the server 90 via the network 200. The wireless device 210 is a transmitting / receiving device connected to the network 200, which transmits and receives various signals via wireless communication R. In the abnormal sound detection system 100, for example, a worker at a vehicle dealership, repair shop, or other facility inputs necessary information and sound data into the abnormal sound detection device 80, which is a mobile terminal, and sends this data via communication to the server 90. The server 90 then determines where the abnormal sound is coming from and outputs the result to the display unit 82 of the abnormal sound detection device 80.

[0050] It should be noted that the above is merely one embodiment, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0051] 10: Vehicle (all-wheel drive vehicle) 14: Front-wheel drive unit 18: Rear-wheel drive unit 20: Front-wheel electric motor 22: Front-wheel power transmission unit 28: Rear-wheel electric motor 30: Rear-wheel power transmission unit 80: Abnormal sound detection device (abnormal sound detection system) 88: Learning model 90: Server (abnormal sound detection system) 100: Abnormal sound detection system G, Gf, Gr: Gear MG: Electric motor PT: Power transmission unit PU: Drive unit

Claims

1. An abnormal noise detection system used to detect abnormal noise in an all-wheel drive vehicle equipped with a front-wheel drive unit and a rear-wheel drive unit, the front and rear of which include electric motors having the same number of poles and power transmission units having at least a partial configuration that is the same in the front and rear, When it is determined that the abnormal noise is caused by the electric motor or a gear in the power transmission device during driving, comparing the time history of torque changes of the front and rear electric motors that occur as the vehicle accelerates or decelerates with the time history of sound pressure changes of the abnormal noise; an abnormal noise detection system that determines that the abnormal noise is coming from one of the front-wheel drive unit and the rear-wheel drive unit, the other of which is determined to have the same increase / decrease periods in the time history of the torque change and the time history of the sound pressure change.

2. 2. The abnormal noise detection system according to claim 1, wherein when it is determined that the abnormal noise is caused by the electric motor or the gear during driving, a guidance is given to encourage the vehicle to accelerate or decelerate.

3. 3. The abnormal sound detection system according to claim 1, wherein the time history of the sound pressure change is applied to a predetermined learning model that indicates a relationship between the time history of the sound pressure change and the cause of the abnormal sound, and the learning model is realized by supervised learning using machine learning, thereby determining whether the abnormal sound is caused by the electric motor or the gear while the vehicle is running.

4. 2. The abnormal noise detection system according to claim 1, wherein, when it is determined that the abnormal noise is caused by the electric motor or the gear during driving, if it is not possible to determine which of the front-wheel drive unit and the rear-wheel drive unit the abnormal noise is coming from, the system determines which of the drive units the abnormal noise is coming from by comparing the sound pressure of the abnormal noise after the measurement position of the abnormal noise has been changed with the sound pressure of the abnormal noise before the measurement position of the abnormal noise was changed.

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