Vehicle control device

Abstract

The vehicle control device (60) comprises: a looseness detection unit (101) that detects looseness in the fastening between a wheel and an axle when a feature amount indicating the degree of looseness in the fastening between the wheel and the axle is equal to or greater than a first determination value; and a distribution ratio adjustment unit (103) that, when a feature amount of either the front wheels (11FL, 11FR) or the rear wheels (11RL, 11RR) is equal to or greater than a second determination value and the feature amount is less than the first determination value, executes an increase process that makes the distribution ratio of the driving force of a vehicle (10) to those wheels higher than before the feature amount of those wheels became equal to or greater than the second determination value.

Description

Vehicle control device

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

[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 looseness of the fastening between the axle of a wheel and the wheel exceeds a threshold value.

[0003] Japanese Patent Application Laid-Open No. 2005-329907

[0004] The above wheel detachment detection device can prompt the driver to stop the vehicle by warning the occupant that the wheel is not properly mounted. However, depending on the situation around the vehicle while it is running, it is not always preferable to stop the vehicle immediately.

[0005] The vehicle control device for solving the above problems is applied to a vehicle configured to include front wheels and rear wheels as wheels and to be able to distribute the driving force of the vehicle to the front wheels and the rear wheels. The vehicle control device includes a looseness detection unit that detects looseness in the fastening between the wheel and the axle when a characteristic amount indicating the degree of looseness in the fastening between the axle of the wheel and the wheel is greater than or equal to a first determination value, and among the front wheels and the rear wheels, when the characteristic amount of one wheel is greater than or equal to a second determination value that is smaller than the first determination value and the characteristic amount of the one wheel is less than the first determination value, a distribution ratio adjustment unit that executes an increase process of increasing the distribution ratio of the driving force of the vehicle to the one wheel as compared with before the characteristic amount of the one wheel becomes greater than or equal to the second determination value.

[0006] The above vehicle control device has an effect that when there is a possibility that looseness has occurred in the fastening between the axle of the wheel and the wheel, it can early detect that looseness has occurred in the fastening.

[0007] FIG. 1 is a configuration diagram showing an outline of a vehicle including the vehicle control device of an embodiment. FIG. 2 is a flowchart showing a series of processes executed by the vehicle control device of FIG. 1. FIG. 3 is an operation diagram showing the transition of a characteristic amount indicating the degree of looseness in the fastening between a wheel and an axle.

[0008] One embodiment of the vehicle control device will be described with reference to Figures 1 to 3. <Vehicle Configuration> Figure 1 shows 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 wheel axle 12F" and the rear wheel axle 12R will be referred to as "rear wheel axle 12R".

[0011] The vehicle 10 is configured to distribute the driving force Fd of the vehicle 10 to the front wheels 11FL, 11FR and the rear wheels 11RL, 11RR. For example, the vehicle 10 includes 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 described as "wheel lateral acceleration sensor 41FL". The sensor corresponding to the right front wheel 11FR is described as "wheel lateral acceleration sensor 41FR". The sensor corresponding to the left rear wheel 11RL is described as "wheel lateral acceleration sensor 41RL". The sensor corresponding to the right rear wheel 11RR is described 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 of the fastening, 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 the 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 status of vehicle 10. For example, if loosening of the fastening between at least one of the multiple wheels 11FL, 11FR, 11RL, 11RR and the axle 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 10 is equipped with a navigation device 55. The navigation device 55 can determine the position of vehicle 10 on a map. In addition, when a destination is set for vehicle 10, the navigation device 55 can display the route that vehicle 10 will take to the destination to the occupants of vehicle 10.

[0022] <Vehicle Control Device> The vehicle control device 60 has a function to set the driving force distribution ratio RT, which is the distribution ratio of the driving force Fd of the vehicle 10 to the front wheels 11FL and 11FR, when the vehicle 10 is in motion. The driving force Fd of the vehicle 10 is the sum of the driving force transmitted from the first power unit 21 to the front wheels 11FL and 11FR and the driving force transmitted from the second power unit 31 to the rear wheels 11RL and 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 and 11FR.

[0023] The vehicle control device 60 includes a processing circuit 61. An example of the processing circuit 61 is an electronic control device. 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-mentioned driving force distribution ratio RT.

[0024] <Principle of loosening of the fastening between the wheel and axle> As described above, the wheel is fastened to the axle by the fastening force of bolts. Therefore, as the fastening force of the bolts weakens while the vehicle 10 is running, the degree of loosening of the fastening between the wheel and axle gradually increases.

[0025] <Functional Configuration of the 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, an entry determination unit 102, and a distribution ratio adjustment unit 103.

[0026] <Looseness Detection Unit> The looseness detection unit 101 detects looseness in the fastening between the wheel and the axle. When the looseness detection unit 101 detects looseness in the fastening between the wheel and the axle, it sends a command to the user interface 50 to notify the occupant that looseness has been detected in the fastening between the wheel and the axle.

[0027] As an example of detecting looseness in the fastening between a wheel and an axle, we will describe the case of detecting looseness in the fastening between the left front wheel 11FL and the front axle 12F. The looseness detection unit 101 acquires the lateral acceleration Gw of the left front wheel 11FL based on the detection signal of the wheel lateral acceleration sensor 41FL. The looseness detection unit 101 derives the amplitude of the lateral acceleration Gw by analyzing the change 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. The loosening detection unit 101 detects loosening of the fastening between the left front wheel 11FL and the front axle 12F if the feature quantity X of the left front wheel 11FL is greater than or equal to the first determination value X1Th. The first determination value X1Th is the criterion for determining whether the degree of loosening of the fastening is large or not. Therefore, if the feature quantity X is less than the first determination value X1Th, it is considered that there is no loosening of the fastening between the left front wheel 11FL and the front axle 12F.

[0028] 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 other than the left front wheel 11FL and the axle will be omitted.

[0029] <Entry Determination Unit> The entry determination unit 102 determines whether or not there is a possibility that the vehicle 10 will enter a specific road. A "specific road" is a road where it is difficult for the vehicle 10 to make an emergency stop. A specific road is, for example, a road where it is difficult to stop on the shoulder and where it is permitted for the vehicle 10 to travel at a relatively high speed. Examples of such specific roads include expressways and bypasses.

[0030] The entry determination unit 102 determines whether the vehicle 10 is traveling on a specific road based on navigation information received from the navigation device 55. If the vehicle 10 is not traveling on a specific road, the entry determination unit 102 determines, based on the navigation information, whether the vehicle 10 is likely to enter a specific road. For example, if the navigation information includes information about the vehicle's route to the destination, the entry determination unit 102 determines that the vehicle 10 is likely to enter a specific road if that route includes a specific road. Alternatively, the entry determination unit 102 may determine that the vehicle 10 is likely to enter a specific road if the entrance to that road exists in the direction the vehicle 10 is currently traveling.

[0031] <Distribution Ratio Adjustment Unit> The distribution ratio adjustment unit 103 sets the driving force distribution ratio RT. The distribution ratio adjustment unit 103 then transmits information regarding the set driving 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.

[0032] The distribution ratio adjustment unit 103 performs an increase process if the feature quantity X of one of the front wheels 11FL, 11FR and rear wheels 11RL, 11RR is greater than or equal to the second determination value X2Th, and the feature quantity X is less than the first determination value X1Th. The second determination value X2Th is a criterion for determining whether or not there is a possibility of loosening in the fastening between the wheel and the axle, and is smaller than the first determination value X1Th. In this case, if the feature quantity X is greater than or equal to the second determination value X2Th, it is considered that there is a possibility of loosening in the fastening between the wheel and the axle.

[0033] In the increase process, the distribution ratio adjustment unit 103 sets the driving force distribution ratio RT such that the distribution ratio of the driving force Fd to the wheel is higher compared to before the wheel feature quantity X becomes equal to or greater than the second determination value X2Th.

[0034] For example, the distribution ratio adjustment unit 103 performs an increase process when the entry determination unit 102 determines that there is a possibility that the vehicle 10 will enter a specific road, and the feature quantity X of one of the front wheels 11FL, 11FR and rear wheels 11RL, 11RR is greater than or equal to the second determination value X2Th, and the feature quantity X is less than the first determination value X1Th. On the other hand, the distribution ratio adjustment unit 103 does not perform an increase process when the entry determination unit 102 determines that there is no possibility that the vehicle 10 will enter a specific road. Furthermore, the distribution ratio adjustment unit 103 does not perform an increase process even when the vehicle 10 is traveling on a specific road.

[0035] Of the front wheels 11FL, 11FR and rear wheels 11RL, 11RR, the wheel whose distribution ratio of the driving force Fd has been increased by the execution of the increase process is referred to as the "target wheel". When the increase process is being executed, the rate of increase of the feature quantity X of the target wheel becomes larger compared to before the start of the increase process. When the feature quantity X of the target wheel becomes equal to or greater than the first determination value X1Th, the distribution ratio adjustment unit 103 terminates the increase process and executes a decrease process to set the driving force distribution ratio RT so that the distribution ratio of the driving force Fd to the target wheel becomes lower.

[0036] For example, in the reduction process, the distribution ratio adjustment unit 103 may set the driving force distribution ratio RT to the value before the start of the increase process. Alternatively, for example, in the reduction process, the distribution ratio adjustment unit 103 may set the driving force distribution ratio RT such that the distribution ratio of the driving force Fd to the target wheel becomes lower compared to before the start of the increase process.

[0037] Referring to Figure 2, a series of processes that change the driving force distribution ratio RT upon 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.

[0038] 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 following step S13, the processing circuit 61 receives navigation information transmitted by the navigation device 55. Then, in step S15, the processing circuit 61 functions as an entry determination unit 102 to analyze the navigation information. This analysis includes determining whether the vehicle 10 is traveling on a specific road and whether the vehicle 10 is likely to enter a specific road. Once the processing circuit 61 has finished analyzing the navigation information, it proceeds to step S17.

[0039] In step S17, the processing circuit 61, functioning as a looseness detection unit 101, determines whether there is a wheel among the multiple wheels 11FL, 11FR, 11RL, 11RR whose feature quantity X is equal to or greater than the first determination value X1Th. That is, the processing circuit 61 determines whether there is a wheel among the multiple wheels 11FL, 11FR, 11RL, 11RR in which looseness in the fastening to the axle has been detected. If there is a wheel in which the feature quantity X is equal to or greater than the first determination value X1Th (S17: YES), that is, if the processing circuit 61 has detected looseness in the fastening between any wheel and the axle, the processing circuit 61 proceeds to step S31. On the other hand, if there is no wheel in which the feature quantity X is equal to or greater than the first determination value X1Th (S17: NO), that is, if looseness in the fastening to the axle has not been detected for any wheel, the processing circuit 61 proceeds to step S19.

[0040] In step S19, the processing circuit 61 determines whether the vehicle 10 is traveling on a specific road. If the processing circuit 61 determines that the vehicle 10 is traveling on a specific road (S19: YES), the processing circuit 61 terminates the series of processes shown in Figure 2. That is, the processing circuit 61 does not execute the increment process described above. On the other hand, if the processing circuit 61 determines that the vehicle 10 is not traveling on a specific road (S19: NO), the processing circuit 61 proceeds to step S21.

[0041] In step S21, the processing circuit 61, functioning as an entry determination unit 102, determines whether or not there is a possibility that the vehicle 10 will enter a specific road. If the processing circuit 61 determines that there is a possibility that the vehicle 10 will enter a specific road (S21: YES), the processing circuit 61 proceeds to step S23. On the other hand, if the processing circuit 61 determines that there is no possibility that the vehicle 10 will enter a specific road (S21: NO), the processing circuit 61 terminates the series of processes shown in Figure 2. In other words, the processing circuit 61 does not perform the above-described increase process.

[0042] In step S23, the processing circuit 61 determines whether there is a wheel among the multiple wheels 11FL, 11FR, 11RL, and 11RR whose feature quantity X is equal to or greater than the second decision value X2Th. If the feature quantity X of at least one wheel among the multiple wheels 11FL, 11FR, 11RL, and 11RR is equal to or greater than the second decision value X2Th (S23: YES), the processing circuit 61 proceeds to step S25. On the other hand, if the feature quantity X of any of the multiple wheels 11FL, 11FR, 11RL, and 11RR is less than the second decision value X2Th (S23: NO), the processing circuit 61 terminates the series of processes shown in Figure 2. In other words, the processing circuit 61 does not perform the increment process described above.

[0043] In step S25, the processing circuit 61 determines whether or not the feature amount X has become equal to or greater than the second determination value X2Th using only one of the front wheels 11FL and 11FR and the rear wheels 11RL and 11RR. When the feature amount X has become equal to or greater than the second determination value X2Th using only one of the front wheels 11FL and 11FR and the rear wheels 11RL and 11RR (S25: YES), the processing circuit 61 proceeds to step S27. On the other hand, when the feature amount X has become equal to or greater than the second determination value X2Th in any of the front wheels 11FL and 11FR and the rear wheels 11RL and 11RR (S25: NO), the processing circuit 61 temporarily ends the series of processes shown in FIG. 2. That is, the processing circuit 61 does not execute the above-described increase process.

[0044] In step S27, the processing circuit 61 executes an increase process by functioning as the distribution ratio adjustment unit 103. In the increase process, the processing circuit 61 changes the driving force distribution ratio RT so that the distribution ratio of the driving force Fd to the wheel in which the feature amount X has become equal to or greater than the second determination value X2Th increases. Then, the processing circuit 61 transmits information regarding the driving force distribution ratio RT to the first control device 22 and the second control device 32. Thereafter, the processing circuit 61 temporarily ends the series of processes shown in FIG. 2.

[0045] In step S31, the processing circuit 61 executes a decrease process by functioning as the distribution ratio adjustment unit 103. In the decrease process, the processing circuit 61 changes the driving force distribution ratio RT so that the distribution ratio of the driving force Fd to the wheel in which the feature amount X has become equal to or greater than the first determination value X1Th decreases. Then, the processing circuit 61 transmits information regarding the driving force distribution ratio RT to the first control device 22 and the second control device 32.

[0046] In subsequent step S33, the processing circuit 61 transmits a command to notify the occupant that loosening of the fastening between the wheel and the axle has been detected to the user interface 50. Thereafter, the processing circuit 61 temporarily ends the series of processes shown in FIG. 2.

[0047] <Operation and Effect of this Embodiment> Referring to FIG. 3, the operation and effect when loosening occurs in the fastening between the wheel and the axle during the running of the vehicle 10 will be described. In FIG. 3, the transition of the feature amount Xb in a comparative example where the distribution ratio of the driving force Fd to the wheel is not changed even when loosening in the fastening to the axle is detected is illustrated by a two-dot chain line.

[0048] When the fastening between the wheel and the axle starts to loosen under the condition that the vehicle 10 is running, as shown in FIG. 3, the feature amount X gradually increases. And at timing t1, the feature amount X becomes equal to or greater than the second determination value X2Th. The wheel for which the feature amount X has become equal to or greater than the second determination value X2Th may also be referred to as a "detected wheel".

[0049] Here, the fact that the feature amount X of the detected wheel becomes equal to or greater than the second determination value X2Th means that there may be loosening in the fastening between the detected wheel and the axle. That is, there may be a decrease in the fastening force of the bolt used for fastening between the detected wheel and the axle. When the vehicle 10 enters a specific road under such circumstances, there is a possibility that the feature amount X will become equal to or greater than the first determination value X1Th while the vehicle 10 is running on the specific road.

[0050] In the comparative example shown in FIG. 3, as shown by the two-dot chain line in FIG. 3, even when the feature amount Xb becomes equal to or greater than the second determination value X2Th, the distribution ratio of the driving force Fd to the detected wheel is not changed. Therefore, the increase acceleration of the feature amount Xb hardly changes before and after timing t1. And at the subsequent timing t3, since the feature amount Xb of the detected wheel becomes equal to or greater than the first determination value X1Th, the driver of the vehicle 10 is notified that loosening has occurred in the fastening between the wheel and the axle.

[0051] In contrast, in the vehicle control device 60 of this embodiment, the driving force distribution ratio RT is changed by performing an increase process at timing t1. That is, in the increase process, the processing circuit 61 changes the driving force distribution ratio RT so that the distribution ratio of the driving force Fd to the detected wheels becomes higher. Then, based on the changed driving force distribution ratio RT and the required value of the driving 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 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 change in accordance with the change in the driving force distribution ratio RT.

[0052] If the fastening between the detected wheel and the axle has actually begun to loosen, changing the driving force distribution ratio RT as described above will increase the rate of increase of the characteristic quantity X of the detected wheel compared to before timing t1, as shown by the solid line in Figure 3. As a result, at timing t2, which is before timing t3, the characteristic quantity X of the detected wheel will be greater than or equal to the first judgment value X1Th. Therefore, the vehicle control device 60 can detect early on if there is a possibility that the fastening between the wheel and the axle is loosening. Furthermore, if the vehicle 10 is not traveling on a specific road when the characteristic quantity X of the detected wheel becomes greater than or equal to the second judgment value X2Th, the vehicle control device 60 can detect the loosening of the fastening between the detected wheel and the axle before the vehicle 10 enters the specific road. In other words, the vehicle control device 60 can notify the driver that the fastening between the detected wheel and the axle is loosening before the vehicle 10 enters the specific road.

[0053] Furthermore, the vehicle control device 60 performs a reduction process at timing t2 when it detects loosening of the fastening between the detected wheel and the axle. As a result, the driving force distribution ratio RT is changed so that the proportion of driving force Fd distributed to the detected wheel becomes lower. Therefore, after timing t2, the rate of increase of the feature quantity X of the detected wheel is reduced. Consequently, the vehicle control device 60 can suppress the degree of loosening of the fastening between the detected wheel and the axle from increasing after it has detected loosening of the fastening.

[0054] <Examples of Modifications> The above embodiment can be implemented with the following modifications. The above embodiment and the following examples of modifications can be combined with each other to the extent that they do not contradict each other technically.

[0055] - The processing circuit 61 may, when it has determined that there is no possibility of the vehicle 10 entering a particular road, change the driving force distribution ratio RT so that the distribution ratio of the driving force Fd to one of the front wheels 11FL, 11FR and rear wheels 11RL, 11RR becomes lower if the feature quantity X of that wheel becomes 2nd determination value X2Th or higher.

[0056] - Even when the processing circuit 61 has determined that there is no possibility of the vehicle 10 entering a specific road, it may perform an increase process if the feature quantity X of one of the front wheels 11FL, 11FR and the rear wheels 11RL, 11RR becomes equal to or greater than the second determination value X2Th.

[0057] - The processing circuit 61 does not have to function as an entry determination unit 102. In this case, if the vehicle 10 is not traveling on a specific road, the processing circuit 61, i.e., the distribution ratio adjustment unit 103, may perform an increase process if the feature quantity X of one of the front wheels 11FL, 11FR and the rear wheels 11RL, 11RR becomes equal to or greater than the second determination value X2Th.

[0058] - The processing circuit 61, i.e., the distribution ratio adjustment unit 103, does not have to reduce the distribution ratio of the driving force Fd to a wheel even if the characteristic quantity X of the wheel whose distribution ratio of the driving force Fd has been increased by the increase processing becomes equal to or greater than the first determination value X1Th.

[0059] 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.

[0060] - 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.

[0061] 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, a second processing circuit that functions as an entry determination unit 102, and a third processing circuit that functions as a distribution ratio adjustment unit 103.

[0062] The processing circuit 61 may be configured as a circuit including one or more dedicated hardware circuits, such as one or more processors that operate according to a computer program, or 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 execute the processes. The memory, i.e., storage medium, includes any available medium that can be accessed by a general-purpose or dedicated computer.

[0063] <Other Technical Ideas> The following describes the technical ideas that can be understood from the above embodiments and modified examples. [Note 1] It is preferable that the loosening detection unit notifies the occupants of the vehicle that loosening has occurred in the fastening between the wheel and the axle when the characteristic quantity of at least one of the front wheels and the rear wheels becomes equal to or greater than the first determination value.

[0064] [Note 2] It is preferable that the distribution ratio adjustment unit does not perform the increase process when it is determined that there is no possibility of the vehicle entering the specific road.

[0065] [Note 3] When the distribution ratio adjustment unit determines that there is no possibility of the vehicle entering the specific road, and the characteristic quantity of one of the front and rear wheels is equal to or greater than the second determination value, it is preferable to perform a reduction process to lower the distribution ratio of the vehicle's driving force to that one wheel compared to before the characteristic quantity of that one wheel became equal to or greater than the second determination value.

[0066] 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."

Claims

1. A vehicle control device applicable to a vehicle having front wheels and rear wheels, and configured to distribute the driving force of the vehicle to the front wheels and the rear wheels, comprising: a looseness detection unit that detects looseness in the fastening between the wheel and the axle when a feature quantity indicating the degree of looseness in the fastening between the wheel and the axle is equal to or greater than a first determination value; and a distribution ratio adjustment unit that, when the feature quantity of one of the front wheels and the rear wheels is equal to or greater than a second determination value which is smaller than the first determination value, increases the distribution ratio of the driving force of the vehicle to that one wheel compared to before the feature quantity of that one wheel became equal to or greater than the second determination value.

2. The vehicle control device according to claim 1, wherein the distribution ratio adjustment unit reduces the distribution ratio of the vehicle's driving force to a wheel when the characteristic quantity of a wheel whose distribution ratio of the vehicle's driving force has been increased by the increase process among the front wheel and the rear wheel becomes equal to or greater than the first determination value.

3. A vehicle control device according to claim 1 or 2, comprising an entry determination unit that determines whether or not the vehicle is likely to enter a specific road on which it is difficult to make an emergency stop, wherein the distribution ratio adjustment unit performs the increase process when it is determined that the vehicle is likely to enter the specific road, and the feature quantity of one of the front wheels and the rear wheels is equal to or greater than the second determination value, and the feature quantity of that one wheel is less than the first determination value.

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