Vehicle control system

Abstract

Even if loosening of the fastening between the wheel and the axle is detected, the system can suppress the progression of that loosening while the vehicle is in motion. [Solution] The vehicle control device 60 includes a looseness detection unit 101 that detects looseness in the fastening between the wheel and the axle, and a distribution ratio adjustment unit 102 that, when the looseness detection unit 101 detects looseness in the fastening between the wheel and the axle, lowers the distribution ratio of the driving force of the vehicle 10 to the wheel in which the looseness was detected compared to before the looseness was detected.

Description

Technical Field

[0005] , , ,

[0001] The present invention relates to a vehicle control device applied to a vehicle.

Background Art

[0002] Patent Document 1 discloses a wheel detachment detection device that warns a driver of a vehicle that a wheel is not properly mounted when a parameter indicating the degree of loosening of the fastening between the axle of a wheel and the wheel exceeds a threshold value.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The above wheel detachment detection device can prompt the driver to stop the vehicle by warning the driver that the wheel is not properly mounted. However, depending on the situation around the vehicle while it is in motion, the driver may not be able to stop the vehicle immediately.

Means for Solving the Problems

[0006] The above-described vehicle control device has the effect of suppressing the progression of loosening during vehicle operation, even if loosening of the fastening between the wheel and the axle is detected. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram showing a vehicle equipped with a vehicle control device according to an embodiment. [Figure 2] Figure 2 is a flowchart showing a series of processes performed by the vehicle control device shown in Figure 1. [Figure 3] Figure 3 is a diagram showing the changes in a characteristic quantity that indicates the degree of loosening of the fastening between the wheel and the axle. [Modes for carrying out the invention]

[0008] One embodiment of a vehicle control device will be described with reference to Figures 1 to 3. <Vehicle Configuration> Figure 1 illustrates a vehicle 10 equipped with a vehicle control device 60.

[0009] Vehicle 10 is equipped with front wheels 11FL, 11FR and rear wheels 11RL, 11RR. The front wheels 11FL, 11FR include the left front wheel 11FL and the right front wheel 11FR. The rear wheels 11RL, 11RR include the left rear wheel 11RL and the right rear wheel 11RR.

[0010] The two front wheels 11FL and 11FR are fastened to the front axle 12F. The front wheels 11FL and 11FR are fastened to the axle 12F, for example, using bolts. The two rear wheels 11RL and 11RR are fastened to the rear axle 12R. The rear wheels 11RL and 11RR are fastened to the axle 12R, for example, using bolts. Hereafter, the front axle 12F will be referred to as "front axle 12F" and the rear axle 12R as "rear axle 12R".

[0011] Vehicle 10 is configured to distribute the driving force Fd of vehicle 10 to the front wheels 11FL, 11FR and the rear wheels 11RL, 11RR. For example, vehicle 10 is equipped with a first drive unit 20 and a second drive unit 30.

[0012] The first drive unit 20 includes a first power unit 21 and a first control device 22 that controls the first power unit 21. The first power unit 21 has at least one of an engine and a drive motor. The driving force output by the first power unit 21 is output to the front axle 12F via the front differential 13F.

[0013] An example of the first control device 22 is an electronic control device. In this case, the first control device 22 has a CPU and a memory that stores a control program executed by the CPU. The first control device 22 controls the first power unit 21 by having the CPU execute the control program in the memory.

[0014] The second drive unit 30 includes a second power unit 31 and a second control device 32 that controls the second power unit 31. The second power unit 31 has at least one of an engine and a drive motor. The driving force output by the second power unit 31 is output to the rear axle 12R via the rear differential 13R.

[0015] An example of the second control device 32 is an electronic control device. In this case, the second control device 32 has a CPU and a memory that stores a control program executed by the CPU. The second control device 32 controls the second power unit 31 by having the CPU execute the control program in the memory.

[0016] The first control unit 22 and the second control unit 32 are capable of sending and receiving various information and commands to and from the vehicle control unit 60 via the in-vehicle network. Therefore, the first control unit 22 can control the first power unit 21 based on commands from the vehicle control unit 60. The second control unit 32 can control the second power unit 31 based on commands from the vehicle control unit 60.

[0017] Vehicle 10 has multiple sensors. For example, vehicle 10 is equipped with multiple wheel lateral acceleration sensors that detect the lateral acceleration of the wheels. Of the multiple wheel lateral acceleration sensors, the sensor corresponding to the left front wheel 11FL is referred to as "wheel lateral acceleration sensor 41FL". The sensor corresponding to the right front wheel 11FR is referred to as "wheel lateral acceleration sensor 41FR". The sensor corresponding to the left rear wheel 11RL is referred to as "wheel lateral acceleration sensor 41RL". The sensor corresponding to the right rear wheel 11RR is referred to as "wheel lateral acceleration sensor 41RR".

[0018] If there is no actual loosening of the fastening between the wheel and the axle, the wheel will not vibrate laterally relative to the axle while the vehicle 10 is in motion. However, as the fastening between the wheel and the axle loosens, the wheel will vibrate laterally relative to the axle. The greater the degree of loosening, the larger the amplitude of the lateral acceleration of the vibrating wheel.

[0019] The wheel lateral acceleration sensors 41FL, 41FR, 41RL, and 41RR detect the lateral acceleration of the corresponding wheels 11FL, 11FR, 11RL, and 11RR. The lateral acceleration of wheels 11FL, 11FR, 11RL, and 11RR based on the detection signals from the wheel lateral acceleration sensors 41FL, 41FR, 41RL, and 41RR is denoted as "Wheel Lateral Acceleration Gw".

[0020] Vehicle 10 has a user interface 50 that notifies the occupants of vehicle 10 of the state of vehicle 10. For example, when loosening of the fastening between at least one wheel and an axle among a plurality of wheels 11FL, 11FR, 11RL, 11RR is detected, the user interface 50 notifies the occupants that loosening of the fastening between the wheel and the axle has occurred. The user interface 50 has, for example, at least one of a display screen and a speaker.

[0021] <Vehicle control device> When vehicle 10 is traveling, the vehicle control device 60 has a function of setting a driving force distribution ratio RT, which is a distribution ratio of the driving force Fd of vehicle 10 to the front wheels 11FL, 11FR. The driving force Fd of vehicle 10 is the sum of the driving force transmitted from the first power unit 21 to the front wheels 11FL, 11FR and the driving force transmitted from the second power unit 31 to the rear wheels 11RL, 11RR. When the driving force Fd is constant, the higher the driving force distribution ratio RT, the greater the driving force transmitted to the front wheels 11FL, 11FR.

[0022] The vehicle control device 60 includes a processing circuit 61. An example of the processing circuit 61 is an electronic control unit. In this case, the processing circuit 61 has a CPU 62 and a memory 63. The memory 63 has a control program executed by the CPU 62. By the CPU 62 executing the control program in the memory 63, the processing circuit 61 sets the above-described driving force distribution ratio RT.

[0023] <Principle of occurrence of loosening of fastening between wheel and axle> As described above, the wheel is fastened to the axle by the fastening force of the bolt. Therefore, when the fastening force of the bolt weakens during the running of vehicle 10, the degree of loosening of the fastening between the wheel and the axle gradually increases.

[0024] <Functional configuration of vehicle control device> The processing circuit 61 of the vehicle control device 60 functions as multiple functional units when the CPU 62 executes the control program in the memory 63. These multiple functional units include a loosening detection unit 101 and a distribution ratio adjustment unit 102.

[0025] <Looseness detection unit> The loosening detection unit 101 detects loosening of the fastening between the wheel and the axle. As an example of detecting loosening in the fastening between a wheel and an axle, we will explain the case of detecting loosening in the fastening between the left front wheel 11FL and the front axle 12F.

[0026] The looseness detection unit 101 acquires the lateral acceleration Gw of the left front wheel 11FL based on the detection signal of the lateral acceleration sensor 41FL for the wheel. The looseness detection unit 101 derives the amplitude of the lateral acceleration Gw by analyzing the changes in the lateral acceleration Gw. The larger the degree of looseness in the fastening between the left front wheel 11FL and the front axle 12F, the larger the amplitude of this lateral acceleration Gw. Therefore, the looseness detection unit 101 acquires the amplitude of the lateral acceleration Gw as a feature quantity X that indicates the degree of looseness in the fastening between the left front wheel 11FL and the front axle 12F. Then, the looseness detection unit 101 detects looseness in the fastening between the left front wheel 11FL and the front axle 12F when the feature quantity X of the left front wheel 11FL is greater than or equal to the threshold XTh. The threshold XTh is the criterion for determining whether the degree of looseness in the fastening is large or not. Therefore, if feature X is less than the threshold XTh, it is assumed that there is no loosening of the fastening between the left front wheel 11FL and the front axle 12F.

[0027] The detection of looseness in the fastening between the right front wheel 11FR and the front axle 12F, the detection of looseness in the fastening between the left rear wheel 11RL and the rear axle 12R, and the detection of looseness in the fastening between the right rear wheel 11RR and the rear axle 12R are the same as the detection of looseness in the fastening between the left front wheel 11FL and the front axle 12F. Therefore, the explanation of the detection of looseness between the wheels and axles other than the left front wheel 11FL will be omitted.

[0028] <Distribution Ratio Adjustment Department> The distribution ratio adjustment unit 102 sets the drive force distribution ratio RT. The distribution ratio adjustment unit 102 then transmits information regarding the set drive force distribution ratio RT to the first control device 22 of the first drive unit 20 and the second control device 32 of the second drive unit 30.

[0029] Specifically, when the looseness detection unit 101 detects looseness between one of the front wheels 11FL, 11FR and the axle of the rear wheels 11RL, 11RR, the distribution ratio adjustment unit 102 sets the driving force distribution ratio RT such that the distribution ratio of the vehicle 10's driving force Fd to that wheel becomes lower compared to before the looseness between that wheel and the axle was detected.

[0030] The following describes several patterns PT1, PT2, and PT3 that require a change in the drive force distribution ratio RT. <Pattern PT1> Pattern PT1 is the case where loosening is detected in the fastening between at least one of the two front wheels 11FL, 11FR and the front axle 12F, while loosening is not detected in the fastening between the rear wheels 11RL, 11RR and the rear axle 12R. In this case, the distribution ratio adjustment unit 102 sets the drive force distribution ratio RT such that the distribution ratio of the drive force Fd to the front wheels 11FL, 11FR is lower compared to before the loosening was detected in the fastening between at least one of the two front wheels 11FL, 11FR and the front axle 12F.

[0031] For example, suppose the driving force distribution ratio RT is 0.8 when vehicle 10 is in a normal state. In this case, 80% of the driving force Fd of vehicle 10 is transmitted to the front wheels 11FL and 11FR, and the remaining 20% ​​is transmitted to the rear wheels 11RL and 11RR. "Normal state" here refers to the state of vehicle 10 when no looseness is detected in the fastening between any of the wheels 11FL, 11FR, 11RL, and 11RR and the axle. If looseness is detected in the fastening between at least one of the two front wheels 11FL and 11FR and the front axle 12F in this state, the distribution ratio adjustment unit 102 lowers the driving force distribution ratio RT to less than 0.8. For example, the distribution ratio adjustment unit 102 may set the driving force distribution ratio RT to 0.6, 0.2, or 0 (zero).

[0032] <Pattern PT2> Pattern PT2 is the case where loosening is detected in the fastening between at least one of the two rear wheels 11RL, 11RR and the rear axle 12R, while loosening is not detected in the fastening between the front wheels 11FL, 11FR and the front axle 12F. In this case, the distribution ratio adjustment unit 102 sets the drive force distribution ratio RT such that the distribution ratio of the drive force Fd to the rear wheels 11RL, 11RR is lower compared to before the loosening was detected in the fastening between at least one of the two rear wheels 11RL, 11RR and the rear axle 12R.

[0033] For example, suppose the driving force distribution ratio RT is 0.8 when the vehicle 10 is in a normal state. In this case, if loosening of the fastening between at least one of the two rear wheels 11RL, 11RR and the rear axle 12R is detected, the distribution ratio adjustment unit 102 will raise the driving force distribution ratio RT to a value higher than 0.8. For example, the distribution ratio adjustment unit 102 may set the driving force distribution ratio RT to 0.9 or to 1.

[0034] <Pattern PT3> Pattern PT3 is the case where loosening of the fastening to the axle is detected by the loosening detection unit 101 in any of the front wheels 11FL, 11FR and the rear wheels 11RL, 11RR.

[0035] In pattern PT3, loosening of the fastening between the left front wheel 11FL and the front axle 12F may be detected, while loosening of the fastening between the left rear wheel 11RL and the rear axle 12R may not be detected. In this case, the distribution ratio adjustment unit 102 sets the drive force distribution ratio RT so that the distribution ratio of the drive force Fd to the front wheels 11FL and 11FR is lower compared to before the loosening of the fastening between the left front wheel 11FL and the front axle 12F was detected.

[0036] In pattern PT3, loosening of the fastening between the left rear wheel 11RL and the rear axle 12R may be detected, while loosening of the fastening between the left front wheel 11FL and the front axle 12F may not be detected. In this case, the distribution ratio adjustment unit 102 sets the drive force distribution ratio RT so that the distribution ratio of the drive force Fd to the rear wheels 11RL and 11RR is lower compared to before the loosening of the fastening between the left rear wheel 11RL and the rear axle 12R was detected.

[0037] In pattern PT3, loosening of the fastening between the left rear wheel 11RL and the rear axle 12R, and loosening of the fastening between the left front wheel 11FL and the front axle 12F may both be detected. In this case, the distribution ratio adjustment unit 102 sets the driving force distribution ratio RT based on the feature quantity X of the left rear wheel 11RL and the feature quantity X of the left front wheel 11FL. For example, if the feature quantity X of the left rear wheel 11RL is greater than the feature quantity X of the left front wheel 11FL, the distribution ratio adjustment unit 102 sets the driving force distribution ratio RT so that the distribution ratio of the driving force Fd to the rear wheels 11RL and 11RR is lower. On the other hand, for example, if the feature quantity X of the left rear wheel 11RL is less than or equal to the feature quantity X of the left front wheel 11FL, the distribution ratio adjustment unit 102 sets the driving force distribution ratio RT so that the distribution ratio of the driving force Fd to the front wheels 11FL and 11FR is lower.

[0038] Referring to Figure 2, a series of processes that change the driving force distribution ratio RT based on the detection of loosening of the fastening between the wheel and the axle will be explained. The processing circuit 61 repeatedly executes the series of processes shown in Figure 2 when the vehicle 10 is in motion.

[0039] In step S11, the processing circuit 61 functions as a looseness detection unit 101 to derive feature quantities X for multiple wheels 11FL, 11FR, 11RL, and 11RR. In the subsequent step S13, the processing circuit 61 functions as a looseness detection unit 101 to perform a looseness determination process. In the looseness determination process, the processing circuit 61 determines whether or not there are any wheels that have experienced loosening of their fastening to the axle, based on the feature quantities X obtained in step S11.

[0040] In the next step S15, the processing circuit 61 determines, based on the result of the loosening determination process in step S13, whether or not there is a wheel among the multiple wheels 11FL, 11FR, 11RL, and 11RR in which loosening of the fastening to the axle has been detected. If there is a wheel in which loosening of the fastening to the axle has been detected (S15: YES), the processing circuit 61 proceeds to step S17. On the other hand, if there is no wheel in which loosening of the fastening to the axle has been detected (S15: NO), the processing circuit 61 terminates the series of processes shown in Figure 2. In other words, the processing circuit 61 does not change the driving force distribution ratio RT.

[0041] In step S17, the processing circuit 61 determines whether or not loosening of the fastening to the axle has been detected in any of the front wheels 11FL, 11FR and the rear wheels 11RL, 11RR. If loosening of the fastening to the axle has been detected in any of the front wheels 11FL, 11FR and the rear wheels 11RL, 11RR (S17: YES), the processing circuit 61 proceeds to step S19. On the other hand, if loosening of the fastening to the axle has been detected in only one of the front wheels 11FL, 11FR and the rear wheels 11RL, 11RR (S17: NO), the processing circuit 61 proceeds to step S31.

[0042] In step S19, the processing circuit 61 determines whether loosening of the fastening to the axle has been detected only in the left front wheel 11FL, out of the left front wheel 11FL and the left rear wheel 11RL. If loosening of the fastening to the axle has been detected only in the left front wheel 11FL (S19: YES), the processing circuit 61 proceeds to step S33. On the other hand, if loosening of the fastening between the left front wheel 11FL and the front axle 12F has not been detected (S19: NO), the processing circuit 61 proceeds to step S21. Also, if loosening of the fastening to the axle has been detected in either the left front wheel 11FL or the left rear wheel 11RL (S19: NO), the processing circuit 61 proceeds to step S21.

[0043] In step S21, the processing circuit 61 determines whether loosening of the connection between the left rear wheel 11RL and the axle has been detected only in the left rear wheel 11RL, out of the left front wheel 11FL and the left rear wheel 11RL. If loosening of the connection between

[0044] In step S23, the processing circuit 61 selects the larger of the feature quantities X of the left front wheel 11FL and the right front wheel 11FR as the feature quantity X of the front wheel. The processing circuit 61 selects the larger of the feature quantities X of the left rear wheel 11RL and the right rear wheel 11RR as the feature quantity X of the rear wheel. Then, the processing circuit 61 determines whether the feature quantity X of the rear wheel is larger than the feature quantity X of the front wheel. If the feature quantity X of the rear wheel is larger than the feature quantity X of the front wheel (S23: YES), the processing circuit 61 proceeds to step S35. On the other hand, if the feature quantity X of the rear wheel is less than or equal to the feature quantity X of the front wheel (S23: NO), the processing circuit 61 proceeds to step S33.

[0045] In step S31, the processing circuit 61 determines whether loosening of the fastening to the axle has been detected only in the front wheels 11FL and 11FR out of the front wheels 11FL and 11FR and the rear wheels 11RL and 11RR. If loosening of the fastening to the axle has been detected only in the front wheels 11FL and 11FR (S31: YES), the processing circuit 61 proceeds to step S33. On the other hand, if loosening of the fastening to the axle has been detected only in the rear wheels 11RL and 11RR out of the front wheels 11FL and 11FR and the rear wheels 11RL and 11RR (S31: NO), the processing circuit 61 proceeds to step S35.

[0046] In step S33, the processing circuit 61 lowers the driving force distribution ratio RT by functioning as a distribution ratio adjustment unit 102. That is, the processing circuit 61 changes the driving force distribution ratio RT so that the distribution ratio of driving force Fd to the front wheels 11FL, 11FR is lower compared to before the loosening of the fastening between the front wheels 11FL, 11FR and the front axle 12F was detected. The processing circuit 61 then transmits information regarding the changed driving force distribution ratio RT to the first control device 22 and the second control device 32. After that, the processing circuit 61 proceeds to step S37.

[0047] In step S35, the processing circuit 61 increases the driving force distribution ratio RT by functioning as a distribution ratio adjustment unit 102. That is, the processing circuit 61 changes the driving force distribution ratio RT so that the distribution ratio of driving force Fd to the rear wheels 11RL, 11RR is lower compared to before the loosening of the fastening between the rear wheels 11RL, 11RR and the rear axle 12R was detected. The processing circuit 61 then transmits information regarding the changed driving force distribution ratio RT to the first control device 22 and the second control device 32. After that, the processing circuit 61 proceeds to step S37.

[0048] In step S37, the processing circuit 61 sends a command to the user interface 50 to notify the occupant that loosening has been detected in the fastening between the wheel and the axle. After that, the processing circuit 61 temporarily terminates the series of processes shown in Figure 2.

[0049] <Operation and Effects of This Embodiment> Referring to Figure 3, the actions and effects of loosening of the fastening between the wheel and the axle while the vehicle 10 is in motion will be explained. In Figure 3, the change in the feature quantity Xb in a comparative example where the distribution ratio of the driving force Fd to the wheel does not change even when loosening of the fastening to the axle is detected is illustrated by a dashed line. Here, the wheel in which loosening of the fastening to the axle is detected may also be called the "detected wheel".

[0050] As the vehicle 10 is in motion, when the connection between the wheel and the axle begins to loosen, the feature quantity X gradually increases, as shown in Figure 3. Then, at timing t1, the feature quantity X becomes greater than or equal to the threshold XTh. Therefore, the processing circuit 61 detects the loosening of the connection between the wheel and the axle.

[0051] In the comparative example, the detection of loosening of the fastening between the wheel and the axle is communicated to the occupant of the vehicle 10 via the user interface 50. However, the distribution ratio of the driving force Fd to the detected wheel remains unchanged. Therefore, as the vehicle 10 continues to move, the feature quantity Xb increases at almost the same rate as before timing t1, as shown by the dashed line in Figure 3.

[0052] In contrast, in the vehicle control device 60 of this embodiment, when the processing circuit 61 detects loosening of the fastening between the wheel and the axle at timing t1, the processing circuit 61 changes the drive force distribution ratio RT so that the distribution ratio of the drive force Fd to the detected wheel becomes lower. Then, based on the changed drive force distribution ratio RT and the required value of the drive force Fd of the vehicle 10, the first control device 22 controls the first power unit 21 and the second control device 32 controls the second power unit 31. As a result, the drive force transmitted from the first power unit 21 to the front wheels 11FL, 11FR and the drive force transmitted from the second power unit 31 to the rear wheels 11RL, 11RR change in accordance with the change in the drive force distribution ratio RT.

[0053] As a result, the distribution ratio of the driving force Fd to the detected wheel is reduced, and as shown by the solid line in Figure 3, the rate of increase of the feature quantity X of the detected wheel becomes smaller compared to before timing t1. Therefore, even if loosening of the fastening between the wheel and the axle is detected, the vehicle control device 60 can suppress the progression of said loosening while the vehicle 10 is running.

[0054] The vehicle control device 60 of this embodiment can further provide the following effects. The wheels are fastened to the axle by bolts. When the vehicle 10 moves forward, the direction of rotation of the left wheels 11FL and 11RL coincides with the direction of bolt rotation that reduces the fastening force of the bolts. Therefore, the loosening of the fastening between the left wheels 11FL and 11RL and the axle tends to be greater than the loosening of the fastening between the right wheels 11FR and 11RR and the axle.

[0055] Therefore, in the vehicle control device 60, when loosening of the fastening to the axle is detected in any of the front wheels 11FL, 11FR and the rear wheels 11RL, 11RR, if loosening of the fastening to the axle is detected only in the left front wheel 11FL out of the two left wheels 11FL, 11RL, the processing circuit 61 reduces the driving force distribution ratio RT. As a result, the processing circuit 61 can lower the distribution ratio of the driving force Fd to the front wheels 11FL, 11FR. Consequently, the vehicle control device 60 can suppress the progression of loosening of the fastening between the left front wheel 11FL and the front axle 12F.

[0056] On the other hand, if loosening of the fastening between the left rear wheel 11RL and the axle is detected only in the left rear wheel 11RL out of the two left wheels 11FL and 11RL, the processing circuit 61 increases the driving force distribution ratio RT. This allows the processing circuit 61 to lower the distribution ratio of the driving force Fd to the rear wheels 11RL and 11RR. Therefore, the vehicle control device 60 can suppress the progression of loosening of the fastening between the left rear wheel 11RL and the rear axle 12R.

[0057] <Example of changes> The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0058] When vehicle 10 is in a normal state, a vehicle in which the distribution ratio of driving force Fd to the front wheels 11FL and 11FR is higher than the distribution ratio of driving force Fd to the rear wheels 11RL and 11RR is described as the first vehicle. In this first vehicle, the front wheels 11FL and 11FR correspond to the "first wheels," and the rear wheels 11RL and 11RR correspond to the "second wheels."

[0059] In a vehicle control device applied to such a first vehicle, the processing circuit 61, i.e., the distribution ratio adjustment unit 102, may, when it detects loosening of the fastening between the front wheels 11FL, 11FR and the front axle 12F, lower the distribution ratio of the driving force Fd to the front wheels 11FL, 11FR to the distribution ratio of the driving force Fd to the rear wheels 11RL, 11RR. This allows the processing circuit 61 to suppress the progression of loosening of the fastening between the front wheels 11FL, 11FR and the front axle 12F.

[0060] In this case, if the processing circuit 61, i.e., the loosening detection unit 101, derives the feature quantity X of the front wheels 11FL and 11FR, it does not need to derive the feature quantity X of the rear wheels 11RL and 11RR. In other words, the processing circuit 61 does not need to have a function to detect loosening of the fastening between the rear wheels 11RL and 11RR and the rear axle 12R.

[0061] When vehicle 10 is in a normal state, a vehicle in which the distribution ratio of driving force Fd to the rear wheels 11RL and 11RR is higher than the distribution ratio of driving force Fd to the front wheels 11FL and 11FR is described as the second vehicle. In this second vehicle, the rear wheels 11RL and 11RR correspond to the "first wheels," and the front wheels 11FL and 11FR correspond to the "second wheels."

[0062] In a vehicle control device applied to such a second vehicle, the processing circuit 61, i.e., the distribution ratio adjustment unit 102, may, when it detects loosening of the fastening between the rear wheels 11RL, 11RR and the rear axle 12R, lower the distribution ratio of the driving force Fd to the rear wheels 11RL, 11RR to the distribution ratio of the driving force Fd to the front wheels 11FL, 11FR. This allows the processing circuit 61 to suppress the progression of loosening of the fastening between the rear wheels 11RL, 11RR and the rear axle 12R.

[0063] In this case, if the processing circuit 61, i.e., the loosening detection unit 101, derives the feature quantity X of the rear wheels 11RL and 11RR, it does not need to derive the feature quantity X of the front wheels 11FL and 11FR. In other words, the processing circuit 61 does not need to have a function to detect loosening of the fastening between the front wheels 11FL and 11FR and the front axle 12F.

[0064] The processing circuit 61, i.e., the loosening detection unit 101, may detect loosening of the fastening between the wheel and the axle using a method different from the method described in the above embodiment. For example, if a sensor for detecting lateral vibration of the wheel is provided on the vehicle, the processing circuit 61 may use the detected value of the sensor to detect loosening of the fastening between the wheel and the axle.

[0065] The drivetrain of a vehicle to which the vehicle control device is applied may have a different configuration from the drivetrain shown in Figure 1, as long as it is possible to change the distribution ratio of the driving force Fd to the front wheels 11FL and 11FR and the distribution ratio of the driving force Fd to the rear wheels 11RL and 11RR.

[0066] The vehicle control device may be configured to include multiple processing circuits. For example, the multiple processing circuits may include a first processing circuit that functions as a loosening detection unit 101 and a second processing circuit that functions as a distribution ratio adjustment unit 102.

[0067] The processing circuit 61 may be configured as a circuit including one or more processors that operate according to a computer program, one or more dedicated hardware circuits such as dedicated hardware that performs at least some of the various processes, or a combination thereof. Examples of dedicated hardware include application-specific integrated circuits (ASICs). The processor includes a CPU and memory such as RAM and ROM, and the memory stores program code or instructions configured to cause the CPU to perform the processes. Memory, i.e., storage media, includes any available media that can be accessed by a general-purpose or dedicated computer.

[0068] In this specification, the expression "at least one" means "one or more" of the desired options. For example, if there are two options, the expression "at least one" means "only one option" or "both of the two options." As another example, if there are three or more options, the expression "at least one" means "only one option" or "a combination of two or more arbitrary options." [Explanation of Symbols]

[0069] 10... Vehicles 11FL, 11FR… Front wheel (an example of a wheel) 11RL, 11RR... Rear wheel (an example of a wheel) 12F…Front axle (an example of an axle) 12R…Rear axle (an example of an axle) 60... Vehicle control device 61…Processing circuit 101...Loosening detection unit 102... Distribution ratio adjustment unit

Claims

1. This applies to a vehicle that has front wheels and rear wheels, and is configured to distribute the vehicle's driving force to the front wheels and the rear wheels. A loosening detection unit that detects loosening of the fastening between the wheel axle and the wheel, The system includes a distribution ratio adjustment unit that, when the loosening detection unit detects loosening of the fastening between one of the front and rear wheels and the axle of that wheel, reduces the distribution ratio of the vehicle's driving force to that wheel compared to before the loosening was detected. Vehicle control device.

2. The distribution ratio adjustment unit is, In a situation where the loosening detection unit has detected loosening of the fastening between the front wheel and the axle of either the front wheel or the rear wheel, If loosening of the fastening between the left front wheel and the axle is detected, but loosening of the fastening between the left rear wheel and the axle is not detected, the distribution ratio of the vehicle's driving force to the front wheels is reduced compared to before the loosening of the fastening between the left front wheel and the axle was detected. If loosening of the fastening between the left rear wheel and the axle is detected, but loosening of the fastening between the left front wheel and the axle is not detected, the distribution ratio of the vehicle's driving force to the rear wheels is reduced compared to before the loosening of the fastening between the left rear wheel and the axle was detected. The vehicle control device according to claim 1.

3. When no loosening of the fastening between the front wheel and the rear wheel and the axle is detected, the wheel with a higher distribution ratio of the vehicle's driving force is the first wheel, and the wheel that is not the first wheel is the second wheel. When the loosening detection unit detects loosening of the fastening between the first wheel and the axle, the distribution ratio adjustment unit lowers the distribution ratio of the vehicle's driving force to the first wheel to a lower ratio than the distribution ratio of the vehicle's driving force to the second wheel. The vehicle control device according to claim 1.

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