JP7382160B2 - Vehicle control device - Google Patents

Description

The present invention relates to a vehicle control device that controls an AWD vehicle that has a transfer clutch that generates a restraining force between a front wheel drive mechanism and a rear wheel drive mechanism.

BACKGROUND ART In an AWD (All Wheel Drive) vehicle that drives front wheels and rear wheels, a transfer clutch is provided that generates a restraining force (fastening force) between a front wheel drive mechanism and a rear wheel drive mechanism.
As such a transfer clutch, one that uses an electromagnetic wet type multi-disc clutch, for example, and has a variable restraint force is known.
The restraint force of the transfer clutch has a large effect on the vehicle's driving performance, such as road performance and handling stability. It is known that various controls can be selected.
For example, in order to strengthen the vehicle's driving force when driving on a road surface with a low coefficient of friction such as an icy or snowy road, or on a rough road such as an uneven road or a muddy road, the restraint force of the transfer clutch is set higher than that during normal driving. It is known to make the mode selectable.
In addition, it is known that in order to improve the turning performance of the vehicle during sports driving such as circuit driving, it is possible to select a control mode in which the restraining force of the transfer clutch at the start of a turn is set lower than during normal driving. There is.

As a conventional technology related to transfer control etc. of an AWD vehicle, for example, Patent Document 1 describes a switching operation that is activated when a driver operates to switch drive modes between 2-wheel drive high mode, 4-wheel drive high mode, and 4-wheel drive low mode. In the control device, it is stated that when the drive mode switching control system fails, the failure of the drive mode switching control system is detected by determining the presence or absence of a stop signal of the shift motor that performs transfer switching, and subsequent drive mode switching control is prohibited. has been done.
Patent Document 2 discloses that in a transfer device that switches between four-wheel drive and two-wheel drive drive modes, if the mode changeover switch is diagnosed as being abnormal, a fail-safe drive mode is set that will not cause any trouble in driving the vehicle. It describes switching to high-speed four-wheel drive mode.
Regarding switching to the 4WD lock state, Patent Document 3 includes a main switching device and a sub-switching device, and when the main switching device and its drive circuit are in failure, the sub-switching device changes the operation to the 4WD lock state. It is stated that the conditions are to permit only when the vehicle speed is less than or equal to a determination value and the slip speed of the driving wheels is less than or equal to a determination value.

Japanese Patent Application Publication No. 2004-322702 Japanese Patent Application Publication No. 2001-287560 Unexamined Japanese Patent Publication No. 2017-43247

In recent years, an AWD control section that controls the restraint force of the transfer clutch and other control sections such as an engine control section that controls the engine and a behavior control section that controls vehicle behavior have been installed above each control section. It has been proposed that AWD control, engine output control, vehicle behavior control, etc. be changed to characteristics different from normal ones all at once based on the control mode selected by the user through cooperative control by a central control unit. .
In such a system, if some kind of failure occurs in the general control unit or other control units, as a failsafe, AWD control will be forcibly returned to normal control, or the currently selected AWD control will be forced to return to normal control. It is conceivable to maintain the current AWD control.

However, for example, if the user selects a high drive force mode that increases the restraining force of the transfer clutch with the intention of escaping from a rough road, and the user is forced to return to normal AWD control, the running performance will deteriorate. There is a concern that the driver may not be able to escape from the rough road.
On the other hand, for example, if the vehicle is locked in such rough road driving mode and cannot return to normal mode, the restraining force of the transfer clutch becomes excessively high during normal driving after escaping from the rough road. There is a concern that this may adversely affect driving performance such as turning performance and fuel efficiency.
In view of the above-mentioned problems, an object of the present invention is to provide a vehicle control device that can ensure vehicle performance desired by a user even when a system failure occurs.

The present invention solves the above-mentioned problems by the following solving means.
The invention according to claim 1 provides an AWD control section that controls the engagement force of a transfer clutch that generates a restraining force between a front wheel drive mechanism and a rear wheel drive mechanism of a vehicle, and a state of a plurality of control sections including the AWD control section. A vehicle control device is provided with a general control unit that can collectively change the function according to a selection operation input by a user, the general control unit having a fail detection unit that detects a failure of the system, and When a fail is detected, information regarding the fail is transmitted to the AWD control section, and when the information regarding the fail is transmitted, the AWD control section is able to operate normally and the fastening force is increased. If a high driving force mode is selected, in which This is a vehicle control device that is characterized by returning to its original state.
According to this, even if a failure occurs in a control unit other than the AWD control unit or the overall control unit itself, if the failure does not occur in the AWD control unit, the transfer clutch is activated in the high driving force mode. By continuing the fastening force control, it is possible to prevent the vehicle from returning to the normal mode against the user's intention and making the driving performance of the vehicle unsuitable for the situation.
In addition, after continuing to control the engagement force of the transfer clutch in the high drive force mode, the high drive force mode is returned to the normal mode when the return conditions are met, forcing the high drive force mode to continue. It is possible to prevent deterioration in driving performance and fuel efficiency when returning to normal driving due to this.

The invention according to claim 2 is characterized in that the AWD control unit includes a vehicle speed detection unit that detects a running speed of the vehicle, and the AWD control unit sets the return condition that the vehicle speed is equal to or higher than a predetermined value. 1. The vehicle control device according to 1.
According to this, for example, when the vehicle speed recovers after escaping from an icy or snowy road or a rough road, the control mode of the AWD control unit is returned from the high driving force mode to the normal mode, so that an appropriate return can be achieved with a simple configuration. You can make it happen.

The invention according to claim 3 is the vehicle control device according to claim 1, wherein the AWD control section uses a return operation input by the user as the return condition.
According to this, the AWD control section returns from the high driving force mode to the normal mode in response to the return operation input by the user, thereby preventing the return to the normal mode contrary to the user's intention, and achieving the above-mentioned effects. can be obtained appropriately.

The invention according to claim 4 is the vehicle control device according to claim 3, characterized in that the return operation is inputted through an input unit that is common to an input unit through which the user inputs the selection operation.
According to this, by using the input section that allows the user to select between high driving force mode and normal mode in the event of a non-failure to return to normal mode in the event of a failure, intuitive operation becomes possible and convenience is improved. do.

The invention according to claim 5 includes a transmission control section that controls a transmission of the vehicle, and a shift operation section that is connected to the transmission control section and allows a user to operate the transmission, and the return operation is 4. The vehicle control device according to claim 3, wherein the input signal is inputted by the speed change operation section.
According to this, even if a failure occurs in the general control unit and the operation of the input unit used for mode selection under normal conditions is not accepted, the normal mode can be changed by operating the gear shift operation unit connected to the transmission control unit. By making it possible to return to normal mode, it is possible to reduce the risk of not being able to return to normal mode.

The invention according to claim 6 includes a power source control unit that controls a power source for driving the vehicle, and a main switch for the driving power source connected to the power source control unit, and the return operation includes: 4. The vehicle control device according to claim 3, wherein the input signal is input by the main switch.
According to this, the high driving force mode is returned to the normal mode in conjunction with stopping the driving power source at the end of the current driving cycle or restarting the driving power source at the start of the next driving cycle. By doing so, it is possible to continue controlling the engagement force of the transfer clutch in the high driving force mode until the end of the driving cycle when the failure occurs, and to perform normal driving in the normal mode from the next driving cycle.

As described above, according to the present invention, it is possible to provide a vehicle control device that can ensure the vehicle performance desired by the user even when a system failure occurs.

1 is a block diagram schematically showing the configuration of a vehicle including a first embodiment of a vehicle control device to which the present invention is applied. It is a flowchart which shows the switching operation of AWD control at the time of a fail in the vehicle control device of a 1st embodiment. It is a flowchart which shows the switching operation of AWD control at the time of a fail in 2nd Embodiment of the vehicle control apparatus to which this invention is applied.

<First embodiment>
Hereinafter, a first embodiment of a vehicle control device to which the present invention is applied will be described.
The vehicle control device of the first embodiment is installed, for example, in a vehicle such as a four-wheeled passenger car that has an AWD system that drives front and rear wheels using an engine.
FIG. 1 is a block diagram schematically showing the configuration of a vehicle having a vehicle control device according to the first embodiment.

As shown in FIG. 1, the vehicle 1 has a power train consisting of an engine 10, a torque converter 20, a lock-up clutch 30, a forward/reverse switching section 40, a variator 50, a front differential 60, a rear differential 70, a transfer clutch 80, etc. .

Engine 10 is an internal combustion engine used as a driving power source for a vehicle.
As the engine 10, for example, a four-stroke turbocharged direct injection gasoline engine can be used.
The engine 10 has its main body and auxiliary equipment controlled by an engine control unit 110, and generates an output torque according to a driver requested torque set based on the driver's accelerator operation or the like.

Torque converter 20 is a fluid coupling that transmits the output of engine 10 to forward/reverse switching section 40 .
Torque converter 20 has a function as a starting device that can transmit engine torque from a stopped state of the vehicle.
The torque converter 20 includes an impeller connected to the output shaft of the engine 10, a turbine connected to the input shaft of the forward/reverse switching section 40, a stator disposed between these, and the like.

The lock-up clutch 30 is a clutch device that is provided in the torque converter 20 and can be switched between a non-engaged state that allows a rotational speed difference between the impeller and the turbine and an engaged state that restrains (directly connects) the impeller and the turbine. .
Engagement and non-engagement of lock-up clutch 30 are controlled by transmission control unit 120.

The forward/reverse switching section 40 is provided between the torque converter 20 and the variator 50, and switches between a forward mode (D range, M range) in which the torque converter 20 and the variator 50 are directly connected, and a reverse mode in which the rotational output of the torque converter 20 is reversed. The reverse mode (R range) transmitted to the variator 50 is switched in response to a command from the transmission control unit 120.
The forward/reverse switching section 40 includes, for example, a planetary gear set.

The variator 50 is a transmission mechanism section that continuously changes the speed of the rotational output of the engine 10 transmitted from the forward/reverse switching section 40.
The variator 50 is, for example, a chain-type continuously variable transmission (CVT) having a primary pulley 51, a secondary pulley 52, a chain 53, and the like.

The primary pulley 51 is provided on the input side of the variator 50 when the vehicle is being driven (on the output side during regenerative power generation), and receives the rotational output of the engine 10.
The secondary pulley 52 is provided on the output side of the variator 50 when the vehicle is being driven (on the input side during regenerative power generation).
The secondary pulley 52 is adjacent to the primary pulley 51 and is rotatable around a rotation axis parallel to the rotation axis of the primary pulley 51.
The chain 53 is formed into an annular shape and is wound around the primary pulley 51 and the secondary pulley 52 to transmit power between them.
The primary pulley 51 and the secondary pulley 52 each have a pair of sheaves that sandwich the chain 53, and the effective diameter can be changed steplessly by changing the interval between each sheave according to the speed change control by the transmission control unit 120. It is possible.

The front differential 60 transmits the driving force transmitted from the variator 50 to the left and right front wheels.
The front differential 60 includes a final reduction gear and a differential mechanism that absorbs the difference in rotational speed between the left and right front wheels.
A drive shaft, which is a rotating shaft that transmits driving force, is provided between the front differential 60 and the left and right front wheel hubs.
The variator 50 and the front differential 60 are directly coupled via a gear shaft mechanism or the like so as to be interlocked.
This gear shaft mechanism, front differential 60, drive shaft, etc. function as a front wheel drive mechanism according to the present invention.

The rear differential 70 transmits the driving force transmitted from the variator 50 via the transfer clutch 80, a propeller shaft (not shown), etc. to the left and right rear wheels.
The rear differential 70 includes a final reduction gear and a differential mechanism that absorbs the difference in rotational speed between the left and right rear wheels.
A drive shaft, which is a rotating shaft that transmits driving force, is provided between the rear differential 70 and the left and right rear wheel hubs.
The propeller shaft, rear differential 70, drive shaft, etc. function as a rear wheel drive mechanism according to the present invention.

The transfer clutch 80 is provided in the middle of the rear wheel drive mechanism that transmits driving force from the variator 50 to the rear differential 70, and connects or disconnects the power transmission path between them.
The transfer clutch 80 is, for example, an electromagnetic wet multi-disc clutch that can change the engagement force (transfer torque capacity, restraining force between the front wheel drive mechanism and the rear wheel drive mechanism) during connection steplessly.
The engagement force (restraining force) of transfer clutch 80 is controlled by transmission control unit 120.
The transfer clutch 80 can adjust the drive torque distribution between the front and rear wheels by changing the engagement force.

The vehicle 1 further includes an engine control unit 110, a transmission control unit 120, a behavior control unit 130, a power steering control unit 140, an overall control unit 150, and the like.
The engine control unit 110 is a power source control section that comprehensively controls the engine 10 and its auxiliary equipment.
The engine control unit 110 sets the driver's requested torque based on the operating amount of an accelerator pedal (not shown), and controls the engine 10 and its auxiliary machinery so that the actual output torque of the engine 10 matches the driver's requested torque. Control.

An ignition switch 111 is connected to the engine control unit 110.
The ignition switch 111 is a main switch through which the user inputs operations to start and stop the engine 10 .
The ignition switch 111 is normally operated at the start and end of a driving cycle (one trip) of the vehicle.

The transmission control unit 120 centrally controls the lock-up clutch 30, the forward/reverse switching section 40, the variator 50, and the like.
The transmission control unit 120 controls the engagement force of the lock-up clutch 30, the gear ratio of the variator 50, etc., depending on the driving state of the vehicle, such as driver requested torque and vehicle speed.
The transmission control unit 120 also operates in accordance with the driving range selection operation by the driver: a forward and automatic shift state (D range), a forward and manual shift state (M range), a reverse state (R range), and a neutral state (N range). , change the parking lock state (P range).
When the M range is selected, the transmission control unit 120 controls the variator 50 to sequentially change a plurality of stepwise gear ratios in response to the driver's upshifting and downshifting operations.
The upshift operation and downshift operation can be performed using, for example, a paddle switch provided on the steering column.

The transmission control unit 120 includes an AWD control section 121 that controls the engagement force (restraint force) of the transfer clutch 80.
The AWD control unit 121 selects two control modes for controlling the engagement force of the transfer clutch 80: a normal mode suitable for normal driving on paved roads, and a low friction coefficient road surface such as icy and snowy roads, uneven roads, unpaved roads, and muddy roads. It has a high driving force mode, which is a special mode suitable for driving on rough roads.
In the high driving force mode, the engagement force of the transfer clutch 80 is set higher than in the normal mode.

The transmission control unit 120 includes a speed change operation section 122 through which a user such as a driver inputs the above-mentioned driving range selection operation.
The shift operation unit 122 is configured as a shift lever (select lever) provided, for example, in the center console of the vehicle, and is configured to select a driving range by swinging its tip.
For example, it is possible to sequentially select the P range, the R range, the N range, and the D range by moving the tip from the frontmost position to the rear side.
Further, from a state in which the D range is selected, the M range is selected by swinging the tip of the shift lever in the left and right direction.

The behavior control unit 130 is a brake control device that comprehensively controls the hydraulic service brake of the vehicle.
The behavior control unit 130 has a function of controlling the hydraulic unit 131.
The hydraulic unit 131 has a function of individually increasing or decreasing the brake fluid hydraulic pressure supplied from the master cylinder 132 for each wheel cylinder 133 of each wheel.
The master cylinder 132 is a pressurizing device that generates a master hydraulic pressure of brake fluid in response to a driver's depression of a brake pedal (not shown).
The master cylinder 132 is provided with a brake booster (vacuum booster) that utilizes the negative pressure in the intake pipe of the engine 10.

The hydraulic unit 131 includes a motor pump that pressurizes brake fluid, and various electromagnetic valves (pressurizing valve, pressure reducing valve, holding valve, etc.) for individually controlling the hydraulic pressure of the wheel cylinder 133 of each wheel. .
For example, when a behavior such as understeer or oversteer occurs, the behavior control unit 130 performs behavior control to generate a braking force difference between the left and right wheels to generate a yaw moment in a direction to suppress the behavior.
In order to perform such behavior control, the behavior control unit 130 includes a yaw rate sensor 135 that detects the yaw rate of the vehicle body.
In addition, when the behavior control unit 130 detects a wheel lock during braking or a sign thereof based on the output of the vehicle speed sensor 134, the behavior control unit 130 periodically lowers the brake fluid pressure in the wheel cylinder 133 of the wheel concerned. Performs anti-lock brake control to restore wheel rotation.
The vehicle speed sensor 134 is provided at a hub portion to which each wheel is attached, and generates a vehicle speed signal according to the rotational speed of the wheel.

The power steering control unit 140 controls a motor that applies a steering force (rack thrust) to a steering device (not shown) that steers the front wheels of the vehicle 1 using a rack and pinion mechanism or the like.
When the vehicle 1 is being driven manually, the power steering control unit 140 controls the motor based on, for example, the output of a torque sensor (not shown) provided on the steering shaft.

The overall control unit 150 controls the engine control unit 110, the transmission control unit 120, the behavior control unit 130, the power steering control unit 140, and other units in an integrated manner.
The overall control unit 150 has a function of changing the characteristics of the vehicle 1 according to a mode selection operation by the user through cooperative control of each unit described above.
A mode selection switch 151 through which a user inputs a mode selection operation is connected to the overall control unit 150.
As the mode selection switch 151, it is possible to use various types of switches, such as a button type or a dial type, provided on an interior member around the driver's seat, such as an instrument panel, a center console, a steering column, or a steering wheel.

The plurality of modes include, for example, a normal mode suitable for normal driving of the vehicle 1, and a high driving force mode suitable for driving on rough roads such as low friction coefficient roads such as ice and snow roads, rough terrain, unpaved roads, muddy roads, etc. It is possible to select special modes such as
When the high driving force mode is selected, for example, the engine control unit 110 makes it easier for the driver to adjust the torque at the beginning of the stroke of the accelerator pedal, and also controls the accelerator pedal in order to suppress disturbances in vehicle behavior caused by excessive engine torque. The correlation between the pedal stroke (depression amount) and the driver's requested torque is changed in the direction that the driver's requested torque is reduced.
The transmission control unit 120 performs speed change control so that the gear ratio becomes larger than in the normal mode, and the AWD control unit 121 performs speed change control so that the engagement force of the transfer clutch 80 becomes larger than in the normal mode (approximately to direct AWD). control).
When the behavior control unit 130 detects slipping of some wheels, the behavior control unit 130 generates braking force in the brakes of the wheels to suppress the slipping, and performs LSD control to prevent other wheels from losing torque, When slope conditions are met, downhill speed control (hill descent control) is performed to apply braking force to each wheel so that the vehicle speed is below a set value.
The power steering control unit 140 changes motor control parameters to suppress kickback when driving on rough roads.

In a vehicle where mode selection is possible by the overall control unit 150 as described above, if a failure occurs in any unit other than the transmission control unit 120, the output control in the engine control unit 110 and the speed change in the transmission control unit 120 are performed. The ratio control, various behavior controls in the behavior control unit 130, motor control in the power steering control unit 140, etc. are configured to return to the default state of the normal mode.
The overall control unit 150 includes a fail detection section (not shown) that detects failures in its own unit and other units using a known self-diagnosis function.
When the fail detection section detects a fail, the overall control unit 150 transmits a signal indicating that a fail has occurred to each unit such as the transmission control unit 120.
However, at this time, if the control of the engagement force in the AWD control unit 121 returns to the normal mode and the engagement force of the transfer clutch 80 decreases, the driving force of the vehicle decreases and the running performance deteriorates, causing the vehicle to escape from the rough road etc. There are concerns that this will not be possible. In other words, even if a failure occurs in any unit, if the AWD control unit 121 is in a state where it can operate normally, it will not immediately return to the normal mode, but will control the fastening force when the failure occurs. It may be preferable to maintain
Therefore, in the first embodiment, the AWD control is switched as described below.
FIG. 2 is a flowchart showing the switching operation of AWD control in the event of a failure in the vehicle control device of the first embodiment.
Below, each step will be explained in order.

<Step S01: High driving force mode selection judgment>
Transmission control unit 120 determines whether high driving force mode is selected by general control unit 150.
If the high driving force mode is selected, the process advances to step S02; otherwise, the series of processes ends (returns).

<Step S02: System fail occurrence determination>
The fail detection section of the overall control unit 150 detects when some kind of fail has occurred in each unit other than the transmission control unit 120, such as the engine control unit 110, behavior control unit 130, and power steering control unit 140, and in the overall control unit 150 itself. Determine whether or not there is one.
If some kind of failure has occurred in a unit other than the transmission control unit 120 that includes the AWD control unit 121 (if the AWD control unit 121 can operate normally), the process advances to step S03, and in other cases, a series of processes is performed. finish.

<Step S03: Continue high driving force mode control>
Transmission control unit 120 continues to control the engagement force of transfer clutch 80 in the high driving force mode.
After that, the process advances to step S04.

<Step S04: Vehicle speed judgment>
Transmission control unit 120 acquires information regarding the vehicle speed detected by vehicle speed sensor 134 via behavior control unit 130 .
Transmission control unit 120 compares the obtained current vehicle speed with a preset threshold.
If the vehicle speed is equal to or higher than the threshold value, the process proceeds to step S09; otherwise, the process proceeds to step S05.

<Step S05: Overall control unit fail determination>
Transmission control unit 120 determines whether or not it is general control unit 150 itself that has failed, based on information from general control unit 150.
If the overall control unit 150 itself does not fail, it is possible to accept the operation input from the mode selection switch 151, so the process proceeds to step S06; otherwise, the process proceeds to step S07.

<Step S06: Determination of mode selection switch return operation>
Transmission control unit 120 determines, based on information from general control unit 150, whether or not a user's operation to return to normal mode has been input to mode selection switch 151.
If there is an operation to return to normal mode, the process advances to step S09; otherwise, the process advances to step S07.

<Step S07: Determining shift operation unit return operation>
The transmission control unit 120 determines whether or not a predetermined normal mode return operation has been input by the user at the shift operation section 122 .
As the normal mode return operation in the shift operation section 122, it is possible to use, for example, an operation of sequentially selecting the D range, the M range, and the D range.
If there is an operation to return to normal mode, the process advances to step S09; otherwise, the process advances to step S08.

<Step S08: Ignition switch off operation judgment>
Transmission control unit 120 determines whether the user has input an off operation to ignition switch 111 based on information from engine control unit 110 .
If the ignition switch 111 has been turned off, the process advances to step S09; otherwise, the process returns to step S03, and the subsequent processes are repeated.

<Step S09: Return to normal mode control>
After continuing the high driving force mode control in step S03, the AWD control unit 121 of the transmission control unit 120 returns the engagement force control of the transfer clutch 80 to the control in the normal mode, assuming that a predetermined return condition is satisfied. .
After that, the series of processing ends.

According to the first embodiment described above, the following effects can be obtained.
(1) Even if each control unit other than the transmission control unit 120 including the AWD control unit 121 or the overall control unit 150 itself fails, if the AWD control unit 121 does not fail, By continuing to control the engagement force of the transfer clutch 80 in the high driving force mode, it is possible to prevent the vehicle from returning to the normal mode against the user's intention and making the driving performance of the vehicle unsuitable for the situation.
In addition, by returning from high driving force mode to normal mode in response to satisfaction of the return conditions set for when a failure occurs, the high driving force mode is forcibly continued when returning to normal driving. It is possible to prevent deterioration of driving performance and fuel efficiency.
(2) By returning from the high driving force mode to the normal mode when the vehicle speed exceeds a threshold value, the control mode of the AWD control unit 121 is set, for example, when the vehicle speed recovers after escaping from an icy or snowy road or rough road. By returning the motor from the high driving force mode to the normal mode, an appropriate return can be performed with a simple configuration.
(3) By returning from the high driving force mode to the normal mode in response to the return operation input by the user, it is possible to prevent a return to the normal mode contrary to the user's intention, and to appropriately obtain the effects described above. .
(4) Since the return operation can be performed using the mode selection switch 151, which the user normally uses to select the control mode, the user can return to the normal mode with an intuitive operation, improving convenience. do.
(5) Even if a failure occurs in the general control unit 150 and the operation of the mode selection switch 151 used for mode selection during normal operation is not accepted, the speed change connected to the transmission control unit 120 including the AWD control unit 121 By making it possible to return to the normal mode by operating the operation unit 122, it is possible to reduce the risk of not being able to return to the normal mode.
(6) By returning from the high driving force mode to the normal mode in conjunction with the off operation of the ignition switch 111, the engagement force of the transfer clutch 80 is maintained in the high driving force mode until the driving cycle at the time of failure occurs ends. In addition to continuing control, it is possible to perform normal driving in normal mode from the next driving cycle.

<Second embodiment>
Next, a second embodiment of a vehicle control device to which the present invention is applied will be described.
The same reference numerals are given to the parts common to the first embodiment, and the explanation thereof is omitted, and the differences will be mainly explained.
In the vehicle control device of the second embodiment, a sports mode used for sports driving such as circuit driving can be selected as a mode for controlling the engagement force of the transfer clutch 80.
In the sport mode, in order to improve the turning performance (rising yaw rate) of the vehicle at the start of a turn, control is performed so that the engagement force of the transfer clutch 80 at the beginning of a turn is lower than in the normal mode.

The normal mode and the sports mode are selected by inputting a selection operation to the mode selection switch 151, similar to the high driving force mode in the first embodiment.
When the sport mode is selected, for example, the engine control unit 110 increases the maximum boost pressure of the engine to increase the maximum torque, and also changes the correlation between the stroke of the accelerator pedal and the driver's requested torque to Change to increase early.
The transmission control unit 120 changes the speed change control to make frequent use of a region with a large reduction ratio in order to maintain the engine speed at a high speed.
In addition, in order to improve the turning performance of the vehicle at the start of a turn, the AWD control unit 121 reduces the engagement force of the transfer clutch 80 compared to the normal mode, and also causes the vehicle to enter the spin mode from the time of a steady turn to the time of exit. In order to suppress this behavior, the engagement force of the transfer clutch 80 is increased compared to the normal mode.
The behavior control unit 130 changes the vehicle behavior control so as to increase the effect of suppressing understeer and to allow oversteer behavior to a certain extent.
The power steering control unit 140 changes the motor control parameters so that the steering force and steering force are slightly larger (heavier) than in the normal mode.
In addition, in the case of a so-called steer-by-wire type steering device in which the steering wheel and steering gear box are not mechanically connected, or a vehicle with a variable steering gear ratio mechanism, the front wheels are adjusted relative to the rotation angle of the steering wheel when selecting sport mode. The rate of change of the steering angle (corresponding to the steering gear ratio of an existing steering device) may be increased (quickened).

FIG. 3 is a flowchart showing the switching operation of AWD control in the event of a failure in the vehicle control device of the second embodiment.
Below, each step will be explained in order.

<Step S11: Sports mode selection judgment>
Transmission control unit 120 determines whether sport mode is currently selected by general control unit 150.
If the sports mode is selected, the process advances to step S12, otherwise the series of processes ends (returns).

<Step S12: System fail occurrence determination>
The overall control unit 150 determines whether a failure has occurred in each unit other than the transmission control unit 120 and the overall control unit 150.
If some kind of fail has occurred, the process advances to step S13; otherwise, the series of processes ends.

<Step S13: Continue sports mode control>
Transmission control unit 120 continues to control the engagement force of transfer clutch 80 in the sport mode.
After that, the process advances to step S14.

<Step S14: Overall control unit fail determination>
Transmission control unit 120 determines whether or not it is general control unit 150 itself that has failed, based on information from general control unit 150.
If the overall control unit 150 itself has not failed, the process advances to step S15; otherwise, the process advances to step S16.

<Step S16: Determination of mode selection switch return operation>
Transmission control unit 120 determines, based on information from general control unit 150, whether or not a user's operation to return to normal mode has been input to mode selection switch 151.
If there is an operation to return to the normal mode, the process advances to step S18; otherwise, the process advances to step S16.

<Step S16: Determining shift operation unit return operation>
The transmission control unit 120 determines whether or not a predetermined normal mode return operation has been input by the user at the shift operation section 122 .
If there is an operation to return to the normal mode, the process advances to step S18; otherwise, the process advances to step S17.

<Step S17: Ignition switch off operation judgment>
Transmission control unit 120 determines whether the user has input an off operation to ignition switch 111 based on information from engine control unit 110 .
If the ignition switch 111 has been turned off, the process advances to step S18; otherwise, the process returns to step S03, and the subsequent processes are repeated.

Also in the second embodiment described above, the same effects as those of the first embodiment described above (excluding those described in section (2)) can be obtained.
Furthermore, unlike the first embodiment, by not returning to the normal mode depending on the vehicle speed, it is possible to prevent the vehicle from returning to the normal mode in a state that the user does not intend, for example, while driving on a circuit.

(Modified example)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
(1) The configurations of the vehicle control device and the vehicle are not limited to the embodiments described above, and can be modified as appropriate.
For example, functions realized by a plurality of units in the vehicle control device of each embodiment may be consolidated into a single unit or the like. On the other hand, functions realized by a single unit or the like in each embodiment may be divided into a plurality of units or the like.
Furthermore, the types of engine and transmission are not particularly limited.
(2) The AWD system of the vehicle of each embodiment is an FWD-based configuration in which the engine and the front wheel drive mechanism are directly connected, and the rear wheel drive mechanism is driven from the front wheel drive mechanism via a variable engagement force mechanism (transfer clutch). However, the configuration of the AWD system is not limited to this and can be changed as appropriate.
For example, an RWD-based configuration may be used in which the rear wheel drive mechanism is directly connected to the engine and the front wheel drive mechanism is driven from the rear wheel drive mechanism via a variable fastening force mechanism.
In addition, in a full-time AWD system that has a mechanical center differential such as a bevel gear type or a planetary gear type to absorb the rotational speed difference between the front wheel drive mechanism and the rear wheel drive mechanism, the front wheel side output part of the center differential and the rear wheel side It may have an electromagnetic type, hydraulic type, etc. clutch that restricts the rotational speed difference with the output part.
(3) In each of the embodiments, the vehicle uses only the engine as the driving power source, but the present invention is not limited to this, and the vehicle may transmit the outputs of the engine and the electric motor to the wheels respectively. It can also be applied to possible engine-electric hybrid vehicles.
(4) The control unit that is cooperatively controlled with other units by the overall control unit is not limited to the configuration of each embodiment, and can be changed as appropriate.
(5) In each embodiment, the conditions for returning from the special mode (high driving force mode, sports mode) are merely examples, and can be changed as appropriate.
Further, the special mode is not limited to the high driving force mode and the sports mode, but may include modes other than these. Furthermore, there are no particular limitations on the specific changes in control of each unit in each mode.

1 Vehicle 10 Engine 20 Torque converter 30 Lock-up clutch 40 Forward/forward switching section 50 Variator 51 Primary pulley 52 Secondary pulley 53 Chain 60 Front differential 70 Rear differential 80 Transfer clutch 110 Engine control unit 111 Ignition switch 120 Transmission control unit 121 AWD control section 122 Shift operation section 130 Behavior control unit 131 Hydraulic unit 132 Master cylinder 133 Wheel cylinder 134 Vehicle speed sensor 135 Yaw rate sensor 140 Power steering control unit 150 General control unit 151 Mode selection switch

Claims (6)

an AWD control unit that controls the engagement force of a transfer clutch that generates a restraining force between the front wheel drive mechanism and the rear wheel drive mechanism of the vehicle;
A vehicle control device comprising: an integrated control unit capable of collectively changing the states of a plurality of control units including the AWD control unit according to a selection operation input by a user;
The overall control unit includes a fail detection unit that detects a system fail, and transmits information regarding the fail to the AWD control unit when detecting the fail,
When the AWD control unit is able to operate normally and a high driving force mode in which the fastening force is greater than the normal mode is selected when the information regarding the fail is transmitted, the AWD control unit The vehicle control device continues to control the fastening force in the high driving force mode, and then returns to the normal mode when a predetermined return condition is satisfied. comprising a vehicle speed detection unit that detects the traveling speed of the vehicle,
The vehicle control device according to claim 1, wherein the AWD control section sets the return condition to be that the vehicle speed is equal to or higher than a predetermined value. The vehicle control device according to claim 1, wherein the AWD control unit uses a return operation input by the user as the return condition. The vehicle control device according to claim 3, wherein the return operation is input through a common input unit through which the user inputs the selection operation. a transmission control unit that controls a transmission of the vehicle;
a gear shift operation unit connected to the transmission control unit and through which a user operates the transmission;
The vehicle control device according to claim 3, wherein the return operation is input by the shift operation section. a power source control unit that controls a power source for driving the vehicle;
and a main switch of the driving power source connected to the power source control unit,
The vehicle control device according to claim 3, wherein the return operation is input by the main switch.

Images