JP2007137307A - Traction control device for four-wheel drive vehicle and traction control method for four-wheel drive vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To implement a traction control device for a four-wheel drive vehicle performing four-wheel drive only under a condition requiring the four-wheel drive. <P>SOLUTION: When a driver turns on a switch 10a for instructing the four-wheel drive to a controller 10, each speed of front, rear, right, left wheels is constantly detected by wheel speed detection sensors 11L, 11R, 21L, 21R after the four-wheel drive vehicle starts traveling and until the vehicle stops. When either of speed difference between the front and rear wheels or speed difference between the right and left wheels is not less than a preset threshold value, a motor 5 is driven by electric power of a generator 4 to perform the four-wheel drive, on the other hand, when the speed difference is smaller than the threshold value, two-wheel drive is performed. Even when the four-wheel drive is performed, the four-wheel drive is switched to the two-wheel drive when neither the speed difference between the front and rear wheels nor the speed difference between the right and left wheels do not consecutively get the threshold value or more, over the preset specified number or more of repeat operations of start/stop. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a driving force control device for a four-wheel drive vehicle and a driving force control method for a four-wheel drive vehicle.

In the prior art described in Japanese Patent Laid-Open No. 2002-152911 “Vehicle four-wheel drive control device” shown in Patent Document 1, in a state where a switch for instructing vehicle four-wheel drive is turned on, The vehicle is always driven by four-wheel drive.
JP 2002-152911 A

  However, the technique of Patent Document 1 has the following problems.

  The first problem is that, even when driving in a season where there is no snowfall, such as in summer, or in an area where there is no snowfall, as long as the driver turns on the switch for instructing four-wheel drive of the vehicle, Since it is driven by wheel drive, the wear of the motor brush advances and there is a risk that the life of the motor will be shortened.

  The second problem is that even if there is no need for four-wheel drive, it is always driven by four-wheel drive, so the generator for driving the motor absorbs part of the engine torque, The accelerator opening that the driver steps on increases and fuel efficiency decreases.

  The present invention has been made in view of the above problems, and can provide a driving force control device for a four-wheel drive vehicle and a driving force control for a four-wheel drive vehicle that can extend the motor life and have good fuel efficiency. The purpose is to realize the method.

  In order to solve the above-mentioned problem, the present invention monitors the wheel speed of each wheel after the vehicle starts running when the driver turns on a switch for instructing four-wheel drive. Four-wheel drive is performed when at least one wheel speed difference between the wheels and between the left and right wheels is greater than a predetermined threshold value.

  According to the driving force control device for a four-wheel drive vehicle and the driving force control method for a four-wheel drive vehicle according to the present invention, even if the driver designates four-wheel drive, the wheel is larger than a predetermined threshold value. Since the four-wheel drive is performed only when a speed difference occurs between the left and right wheels and the front and rear wheels and it is determined that the four-wheel drive is necessary, the following effects can be obtained. Can play.

  That is, when there is no need for four-wheel drive, it is possible to stop the four-wheel drive, suppress unnecessary wear of the motor brush, extend the motor life of the four-wheel drive vehicle, and improve fuel efficiency. Can be improved. On the other hand, when the four-wheel drive is required, the vehicle can be immediately returned to the four-wheel drive.

  BEST MODE FOR CARRYING OUT THE INVENTION The best embodiments of a driving force control device for a four-wheel drive vehicle and a driving force control method for a four-wheel drive vehicle according to the present invention will be described below in detail with reference to the drawings.

(First embodiment)
First, a first embodiment of the present invention will be described with reference to FIG.

  FIG. 1 is a system configuration diagram showing an example of a configuration of a hybrid type four-wheel drive vehicle (electric four-wheel drive vehicle: e-4WD) equipped with a driving force control device for a four-wheel drive vehicle according to the present invention. One of these is driven by an engine (internal combustion engine) and the other wheel is driven by a motor (electric motor), and can be driven by switching between two-wheel drive and four-wheel drive depending on the situation 1 shows a schematic configuration of a hybrid four-wheel drive vehicle.

  First, the configuration of FIG. 1 will be described. In the driving force control apparatus 100 for a four-wheel drive vehicle according to the present embodiment shown in FIG. 1, one drive wheel (in the example of FIG. Wheels 1L, 1R) are driven. Further, a part of the output torque of the engine 3 is transmitted to the generator 4 through an endless belt (not shown) and converted into electric power. The electric power generated by the generator 4 is supplied to the motor 5 via an electric wire indicated by a broken line, and the motor 5 is driven using only the electric power generated by the generator 4. The other drive wheels (the left and right wheels 2L and 2R in the rear in the example of FIG. 1) are driven by the drive torque of the motor 5 via the speed reducer 6 and a clutch (not shown).

  The e-4WD controller 10 (hereinafter abbreviated as controller 10) controls the overall operation of the driving force control apparatus 100 for a four-wheel drive vehicle, and performs two-wheel drive (2WD) and four-wheel drive (4WD). It has a function that can be switched at any time according to the situation, and can control four-wheel drive as required.

  An engine speed detection sensor 31 is connected to the engine 3, and the speed of the engine 3 detected by the engine speed detection sensor 31 is output to the controller 10. The engine 3 is connected to a throttle opening detection sensor 32 and an electronic control throttle 33. The electronic control throttle 33 receives electronic control throttle information from the controller 10 and opens the throttle valve. The degree is set to a designated state, the set opening degree of the throttle valve is detected by the throttle opening degree detection sensor 32, and is returned to the controller 10.

  The left and right front wheels 1L, 1R and the left and right rear wheels 2L, 2R are provided with wheel speed detection sensors 11L, 11R and wheel speed detection sensors 21L, 21R for detecting the respective wheel speeds. The wheel speeds of the respective wheels are output to the controller 10.

  Further, the transmission 7 is provided with a shift position detection sensor 71 that detects the shift position of the shift lever, and the detected shift position of the shift lever is output to the controller 10.

  Further, the accelerator pedal 8 is provided with an accelerator opening sensor 81 for detecting an accelerator opening indicating the depression amount of the accelerator pedal 8, and the detected accelerator opening is output to the controller 10. .

  Furthermore, the parking brake 9 is provided with a brake switch 91 that detects the operation / non-operation of the parking brake 9, and the detected state of the parking brake 9 is output to the controller 10.

  Further, a switch for instructing the four-wheel drive by the driver, that is, an e-4WD switch 10a (ON: instruction to switch to four-wheel drive, OFF: two-wheel drive) is provided, and the e-4WD switch 10a The ON / OFF state is also output to the controller 10.

  The controller 10 collects information from the sensors and switches as described above, thereby controlling the overall operation of the driving force control apparatus 100 and driving the four-wheel drive vehicle in a desired driving state. ing.

  For example, the controller 10 includes the front and rear wheel speeds detected by the wheel speed sensors 11L, 11R, 21L, and 21R, the accelerator opening detected by the accelerator opening sensor 81, and the engine speed detection sensor. Based on the engine surplus torque obtained using the engine 3 rotation speed detected at 31, the power generation amount to be generated is commanded to the alternator type generator 4 capable of generating variable generation power. To do. The alternator generator 4 generates generated power corresponding to the commanded power generation amount and supplies the motor 5 with power. The motor 5 is rotationally driven by the electric power from the generator 4 and drives the left and right rear wheels 2L, 2R. Such control is a basic control function in the controller 10 when four-wheel drive is performed.

  In the present invention, when the controller 10 receives the ON operation of the e-4WD switch 10a by the driver, the controller 10 first determines whether or not the four-wheel drive is necessary without shifting to the control of the four-wheel drive. If it is determined that four-wheel drive is necessary, control is performed to start four-wheel drive for the first time. Conversely, if it is determined that four-wheel drive is not necessary, driving Even if the person is turning on the e-4WD switch 10a and instructing four-wheel drive, control is performed to suppress useless four-wheel drive.

  That is, after starting the engine 3, when the controller 10 detects that the e-4WD switch 10a for instructing four-wheel drive is set to ON by the driver, the accelerator pedal 8 is depressed and the four-wheel drive vehicle is depressed. After the vehicle starts traveling, the wheel speeds of the wheels 1L, 1R, 2L, 2R are continued from the wheel speed sensors 11L, 11R, 21L, 21R provided on the front, rear, left and right wheels 1L, 1R, 2L, 2R. Start the monitor operation.

  The controller 10 calculates the wheel speed difference between the front and rear wheels and between the left and right wheels on the basis of the wheel speeds of the wheels 1L, 1R, 2L, and 2R that are continuously monitored. Whether there is any wheel speed difference between the wheels, or whether any wheel speed difference between the front and rear wheels or between the left and right wheels is greater than a predetermined threshold value. If there is a wheel speed difference, or if the wheel speed difference is larger than the threshold value, it is determined that the wheel slip has exceeded the allowable limit, and the four wheels Control to drive. If a state in which the wheel speed difference exceeds the threshold value occurs when the four-wheel drive vehicle stops, the vehicle is controlled to start with four-wheel drive when starting next.

  On the other hand, if there is no wheel speed difference between the front and rear wheels and between the left and right wheels, or if the wheel speed difference is not greater than the above threshold, the wheel slip exceeds the allowable limit. Therefore, even if the driver turns on the e-4WD switch 10a for instructing four-wheel drive, control is performed so that two-wheel drive is performed.

  It should be noted that when sudden acceleration / deceleration is performed, such as when the four-wheel drive vehicle starts or stops, depending on the road surface condition such as freezing, the distance between the front and rear wheels or the right and left wheels An increase in wheel speed difference is particularly likely to occur. Accordingly, when acceleration / deceleration exceeding a predetermined acceleration threshold is detected based on the wheel speeds of the wheels 1L, 1R, 2L, 2R, either between the front and rear wheels or between the left and right wheels. It is also possible to determine whether there is any wheel speed difference, or whether the wheel speed difference between the front and rear wheels or between the left and right wheels is greater than a predetermined threshold. good.

  FIG. 2 is a schematic diagram schematically showing a situation in which a speed difference occurs between the front and rear wheels and between the left and right wheels, and FIG. 2 (A) shows the wheel speed between the front and rear wheels. The solid lines indicate the wheel speeds of the front wheels 1L and 1R, and the broken lines indicate the wheel speeds of the rear wheels 2L and 2R. On the other hand, FIG. 2 (B) shows the state of occurrence of a wheel speed difference between the left and right front wheels 1L and 1R or the rear wheels 2L and 2R.

  As shown in FIG. 2A, in general, in a state where rapid acceleration / deceleration occurs at the time of starting or stopping, the wheel speeds of the front wheels 1L, 1R and the rear wheels 2L, A difference in speed is likely to occur between the 2R wheel speeds, and when the vehicle is running at a constant speed, the wheel speeds between the two wheels are substantially the same, and the wheel speed difference is unlikely to occur. Similarly, as shown in FIG. 2 (B), the wheel speed between the left and right wheels 1L, 1R or the wheels 2L, 2R is generally abruptly accelerated or decelerated at the time of starting or stopping. In this state, a wheel speed difference between the left and right wheels is likely to occur. When the vehicle is in a constant speed traveling state, the wheel speed difference is unlikely to occur between the two wheels.

  Next, an example of the operation related to such four-wheel drive control will be described with reference to the flowchart shown in FIG. FIG. 3 is an operation flowchart for explaining an example of the operation of the four-wheel drive control in the driving force control apparatus 100 for a four-wheel drive vehicle of the present invention.

  In the operation flowchart of FIG. 3, the engine 3 is started with the e-4WD switch 10a instructing the four-wheel drive to be turned on, and then the accelerator pedal 8 is depressed to start the vehicle running. Then, after that, a series of operations in the controller (e-4WD controller) 10 of the driving force control apparatus 100 until the stop is described.

  As shown in FIG. 3, the controller 10 indicates that the four-wheel drive is to be performed. E-4WDflag (ON: a state where four-wheel drive is necessary, that is, an operation state (standby) of four-wheel drive, OFF: 4 A state where no wheel drive is required, that is, a four-wheel drive stop state) is incorporated separately from the e-4WD switch 10a operated by the driver, and the e-4WD switch 10a is in an ON state, and the e-4WD flag If the e-4WD flag is OFF, the two-wheel drive operation is performed regardless of whether the e-4WD switch 10a is ON or OFF.

  Here, the initial state of the e-4WD flag at the start of the engine 3 may be set to either ON or OFF, but immediately after the start of the engine 3 where the road surface condition has not yet been grasped, As long as the e-4WD switch 10a for instructing the four-wheel drive is set to ON, the initial setting is made so that the e-4WD flag is fixed to ON when starting the engine so that the vehicle starts with four-wheel drive. Also good.

  In the operation flowchart of FIG. 3, when the e-4WD switch 10a is in the ON state, the controller 10 first determines whether the e-4WD flag is to be driven after the engine 3 is started. It is confirmed whether or not it is in an OFF state (step S1). When e-4WD flag is ON (NO in step S1), the four-wheel drive vehicle is in a state where it should perform four-wheel drive (4WD), so that the process proceeds to step S13 to perform control for four-wheel drive. E-4WDflag continues to be in the ON state (step S13). Thereafter, the operations after step S14 described later are performed.

  On the other hand, if the e-4WD flag is OFF (YES in step S1), whether the four-wheel drive vehicle should be controlled to be four-wheel drive (4WD) or two-wheel drive (2WD) according to the road surface state, That is, in order to determine whether or not the four-wheel drive is necessary, the wheel speed sensors 11L, 11R, 21L, and so on are triggered by the fact that the accelerator is stepped on and the vehicle starts to travel (step S2). Monitoring of the wheel speed of each wheel detected by 21R is started, and the monitoring operation is continued until it stops thereafter.

  Next, the wheel speed difference Vlr between the left and right wheels 1L and 1R and between 2L and 2R is calculated (step S3), and the wheel speed difference Vlr between the left and right wheels is set to a predetermined left and right threshold (for example, 3 rpm). It is determined whether it is smaller than () (step S4). If the wheel speed difference Vlr between the left and right wheels is greater than the left / right threshold (NO in step S4), the wheel slip has occurred beyond the allowable limit and four-wheel drive is required. In step S13, control for four-wheel drive is performed, and e-4WDflag indicating that the four-wheel drive is to be performed is set to ON (step S13). Thereafter, the operations after step S14 described later are performed.

  Here, when the four-wheel drive vehicle is stopped, if it is detected that the wheel speed difference Vlr between the left and right wheels is equal to or greater than the left and right threshold, the e-4WD flag is set to the ON state. Since the control for four-wheel drive is performed, the start control is performed by the four-wheel drive at the next start by the accelerator ON. The left / right threshold value can be set to an arbitrary value depending on the travel region of the vehicle, but is set to a value that takes into account the wheel speed difference that occurs when the four-wheel drive vehicle turns. It is necessary.

  On the other hand, if the wheel speed difference Vlr between the left and right wheels is smaller than the left and right threshold value (YES in step S4), then, between the front and rear left wheels 1L and 2L and between the front and rear right wheels 1R and 2R, respectively. The wheel speed difference Vfr is calculated (step S5), and it is determined whether or not the wheel speed difference Vfr between the front and rear wheels is smaller than a predetermined front and rear threshold (for example, 3 rpm) (step S6).

  When the wheel speed difference Vfr between the front and rear wheels is larger than the front and rear threshold value (NO in step S6), as in the case where the wheel speed difference Vlr between the left and right wheels is equal to or larger than the left and right threshold value, Since the slip of the wheel has occurred beyond the allowable limit and four-wheel drive is necessary, the process proceeds to step S13 to perform control for four-wheel drive and to perform four-wheel drive. The e-4WD flag indicating that it is present is set to ON (step S13).

  Thereafter, the process proceeds to step S14, and the counter T1 is cleared in order to initialize the counter T1 that counts the number of start / stop times that does not require four-wheel drive (step S14). Further, in order to check whether or not the four-wheel drive vehicle has stopped, a vehicle body speed Vv of the four-wheel drive vehicle is calculated (step S15), and whether or not the vehicle body speed Vv is “0 km / h”. Is checked (step S16).

  When the vehicle body speed Vv is not “0 km / h” (NO in step S16), the four-wheel drive vehicle is in a state of traveling by four-wheel drive, and the process proceeds to step S3. In order to determine whether or not to continue, the operation returns to the operation of calculating the wheel speed difference Vlr between the left and right wheels. On the other hand, when the vehicle body speed Vv is “0 km / h” (YES in step S16), the four-wheel drive vehicle is in a stopped state, and the process proceeds to step S2 to monitor the start by the next accelerator ON operation. To do. At this time, since e-4WDflag is already set to ON and control for four-wheel drive is performed, start control is performed by four-wheel drive at the time of start by the next accelerator ON.

  On the other hand, when the wheel speed difference Vfr between the front and rear wheels is smaller than the front and rear threshold value (YES in step S6), the wheel speed difference between the left and right wheels and the front and rear wheels is determined in advance. Left-right threshold, smaller than the front-rear threshold, determines that the four-wheel drive is in an unnecessary range, and then checks whether the four-wheel drive vehicle has stopped. The vehicle speed Vv is calculated (step S7), and it is checked whether the vehicle speed Vv is “0 km / h” (step S8).

  When the vehicle body speed Vv is not “0 km / h” (NO in step S8), the four-wheel drive vehicle is in a traveling state under a situation where wheel slip occurs only within an allowable limit. Returning to step S3, the monitoring operation of the wheel speed differences Vlr and Vfr between the left and right and front and rear wheels during the subsequent travel is continued. If the wheel speed difference Vlr, Vfr between the left and right wheels and the front and rear wheels is larger than the left and right threshold values and the front and rear threshold values during the monitoring operation in the running state (NO in step S4, or (NO in step S6), the process proceeds to step S13, and control for switching to four-wheel drive is performed. Here, if the vehicle is already running with four-wheel drive, the four-wheel drive continues as it is.

  On the other hand, if the vehicle body speed Vv is “0 km / h” (YES in step S8), the four-wheel drive vehicle is in a stopped state, and if the vehicle has been driven by two-wheel drive until it stops, During traveling up to, the wheel speed difference Vlr, Vfr was not so large as to require four-wheel drive. However, if you have been traveling with four-wheel drive until you stop, you will not need four-wheel drive to determine whether you should switch from four-wheel drive to two-wheel drive at the next start. The value of the counter T1 that counts the number of stops is checked (step S9).

  When the value of the counter T1 is smaller than a predetermined number of times, for example, 5 (NO in step S9), the counter T1 is incremented by “1” (step S12), and the step is performed unless the engine 3 is stopped. Returning to S2, the next start of the four-wheel drive vehicle is ready.

  On the other hand, when the value of the counter T1 is counted up to the specified number of times (for example, 5 times) or more (YES in step S9), the number of repeated start / stop operations of the four-wheel drive vehicle is equal to or more than the specified number of times. In this case, the difference between the left and right and front and rear wheel speeds does not continuously increase beyond the left and right threshold values and the front and rear threshold values. Therefore, there is no situation where the wheel slip does not exceed the allowable limit continuously over the specified number of starts / stops, and stable start / stop operation and running are possible. It is determined that the four-wheel drive is unnecessary, and the four-wheel drive (4WD) is stopped and switched to the two-wheel drive (2WD), and the e-4WD flag is switched from ON to OFF, and the four-wheel drive is unnecessary. (S10).

  Thereafter, in order to initialize the counter T1, after clearing the counter T1 (step S11), unless the engine 3 stops, the process returns to step S2 to prepare for the next start of the four-wheel drive vehicle. As a result, since e-4WDflag is set to an OFF state and control for two-wheel drive is performed, the start control is performed by two-wheel drive at the time of start by the next accelerator ON.

  Note that the operation flowchart shown in FIG. 3 repeats the loop operation as long as the engine 3 is in an ON state.

  By performing the four-wheel drive control in the controller 10 as described above, if the four-wheel drive is not necessary, it is assumed that the e-4WD switch instructing the four-wheel drive has been turned on by the driver. However, by stopping the four-wheel drive and performing the two-wheel drive, useless wear of the motor brush can be suppressed and the life of the four-wheel drive vehicle can be extended. On the other hand, when a state where four-wheel drive is required is reached, it is possible to immediately return to four-wheel drive.

  Also, even when four-wheel drive is being performed, the difference in wheel speed between the left and right and front and rear wheels over a predetermined number of times (for example, five times) as the number of repeated start and stop operations of the four-wheel drive vehicle. If neither Vlr nor Vfr is continuously greater than the left and right threshold values and the front and rear threshold values, it is possible to switch back from four-wheel drive to two-wheel drive. The wheel drive is stopped to suppress motor brush wear. In this case, instead of the number of repeated starting and stopping operations, for example, the wheel speed difference Vlr and Vfr are both the left and right thresholds, When the case where the value becomes larger than the front-rear threshold value does not occur continuously, control may be performed so as to switch back from four-wheel drive to two-wheel drive.

  Immediately after starting the engine 3 for which the road surface condition cannot be grasped, as described above, the engine 3 is started as long as the driver sets the e-4WD switch 10a for instructing four-wheel drive. As an initial state of the e-4WD flag at the time, the e-4WD flag may be fixed to ON and the vehicle may start by four-wheel drive.

  As a result, while the information on the road surface condition does not yet exist in the controller 10 of the four-wheel drive device 100, such as immediately after the engine 3 is started, the vehicle is fixed to the four-wheel drive until the collection of the information on the road surface condition is completed. For example, in situations such as when starting from an icy road surface, against the driver's intention, the problem of starting with two-wheel drive instead of four-wheel drive is prevented. can do.

Here, as the time when the controller 10 completes the collection of the information on the road surface condition, the wheel speed difference Vlr between the left and right and front and rear wheels at least during the period from the start of the engine 3 to the stop. , Vfr may be the time when the controller 10 grasps the information, or as shown in step S9 of FIG. 3, by repeating the start / stop operation for a predetermined number of times (for example, 5 times), It is good also as the time when it became possible to acquire the information regarding wheel speed difference Vlr and Vfr between the front and rear wheels stably.
(Second Embodiment)
Next, a second embodiment of the present invention will be described using the configuration of FIG. 1 and the operation flowchart of FIG. In the present embodiment, as shown in the configuration of FIG. 1, a driver or a passenger of a four-wheel drive vehicle can connect to the controller 10 via a connection interface (for example, a USB cable or Bluetooth). An example of the control operation of the four-wheel drive when 20 is carried is described.

  That is, in this case, the mobile phone 20 accesses an information center that stores weather information and the like in each region such as the traveling region of the four-wheel drive vehicle via a network not shown in FIG. It is possible to acquire weather information in the travel region of the four-wheel drive vehicle and transmit the acquired weather information to the controller 10 via the connection interface. The controller 10 performs an operation of controlling the operation of the four-wheel drive based on the weather information from the mobile phone 20 when the engine 3 is started.

  Below, an example of the operation | movement in the controller 10 in this embodiment is demonstrated using the operation | movement flowchart shown in FIG. FIG. 4 is an operation flowchart for explaining a different example of the operation of the four-wheel drive control in the driving force control apparatus 100 for a four-wheel drive vehicle according to the present invention. When the engine 3 is started, FIG. An example of the operation executed prior to the execution of the operation flowchart based on the determination of “e-4WDflag” described in FIG.

  In the operation flowchart of FIG. 4, when the engine 3 is started with the driver turning on the e-4WD switch 10a for instructing four-wheel drive, first, the mobile phone 20 is connected to the controller via the connection interface. 10 is checked (step S21). If the cellular phone 20 is not connected to the controller 10 via the connection interface (NO in step S21), the process jumps to step S1 in FIG. 3 to perform the determination operation by the e-4WD flag described above, and the determination Depending on the result, the operation shown in the operation flowchart of FIG. 3 is performed.

  On the other hand, when the mobile phone 20 is connected to the controller 10 via the connection interface (YES in step S21), the controller 10 sends the current date and time, the four wheels to the mobile phone 20 via the network. Information on the area where the driving vehicle is traveling is specified, and an instruction is given to acquire weather information for the specified date and time and area.

  The mobile phone 20 that has received such an instruction reads the current date and time from the clock information built in the mobile phone 20, identifies the current running area from the cell area of the communication radio wave, and identifies the current running date and time. In order to obtain weather information in the middle area, an information center that stores weather information of each area is accessed via the network.

  After that, when the mobile phone 20 receives the weather information about the identified traveling area at the current date and time from the accessed information center via the network, the mobile phone 20 returns the weather information to the requesting controller 10. By such an operation, the controller 10 acquires weather information regarding the traveling area via the mobile phone 20 (step S22).

  With reference to the weather information of the area where the vehicle is traveling, the controller 10 determines whether or not the area is a snowy area (step S23). If it is determined that it is not a snowy area (NO in step S23), e-4WD flag is turned off and e-4WD (four-wheel drive) is determined to be an area where four-wheel drive is unnecessary and there is no risk of snow on the road surface. ) Is set to a state in which the two-wheel drive is performed, the process jumps to step S1 in FIG. 3, and the determination operation by the e-4WD flag described above is performed. Depending on the determination result, FIG. The operation shown in the operation flowchart is performed.

  On the other hand, if it is determined that it is a snowy area (YES in step S23), it is further determined whether or not the current season is the snowy season of the area (step S24). If it is determined that it is not currently a snowy season (NO in step S24), even if it is a snowy region, it is assumed that there is no risk of snow on the road surface, and e-4WD flag is turned off to drive four wheels. Is not necessary, and is set to a state in which two-wheel drive is performed, jumps to step S1 of FIG. 3, performs the determination operation by the e-4WD flag described above, and performs the operation of FIG. 3 according to the determination result. The operation shown in the flowchart is performed.

  On the other hand, if it is determined that it is a snowy season (YES in step S24), it is determined whether or not the weather information includes information indicating snowfall. If the information indicating snowfall is included, the road surface E-4WD flag is turned on and e-4WD (four-wheel drive) is in operation (standby) state. Then, the process jumps to step S1 in FIG. 3 to perform the determination operation by the e-4WD flag described above, and performs the operation shown in the operation flowchart of FIG. 3 according to the determination result.

  As described above, in the case of the present embodiment, when the engine 3 is started, since the road surface condition is unknown, the e-4WD flag is fixedly initially set to ON and the four-wheel drive is performed (standby). Unlike the case of FIG. 3 as described above, when the engine 3 is started, the function of the mobile phone 20 is used to grasp the road surface condition in advance from the weather information of the area where the vehicle is running. Depending on the predicted road surface condition, e-4WDflag can be set to either ON (four-wheel drive operating state (standby)) or OFF (four-wheel drive pause state).

  Note that the time point when weather information in a traveling area is acquired by the mobile phone 20 is not limited to the time when the engine 3 is started as described above, and the weather information is acquired at any time point when the four-wheel drive vehicle is traveling. It does not matter if you do.

  As described above, by utilizing the function of the mobile phone 20, the four-wheel drive operation including the start of the engine 3 can be performed only when it is really necessary. The life of the drive vehicle can be extended, and further, fuel efficiency can be improved by suppressing four-wheel drive.

1 is a system configuration diagram showing an example of a configuration of a hybrid type four-wheel drive vehicle equipped with a driving force control device for a four-wheel drive vehicle according to the present invention. It is the schematic diagram which showed typically the condition where the speed difference has generate | occur | produced in the wheel speed between the front-and-rear wheels and between the left and right wheels. It is an operation | movement flowchart for demonstrating an example of the operation | movement of four-wheel drive control in the driving force control apparatus of the four-wheel drive vehicle of this invention. It is an operation | movement flowchart for demonstrating the example from which the operation | movement of four-wheel drive control differs in the driving force control apparatus of the four-wheel drive vehicle of this invention.

Explanation of symbols

1L, 1R ... left and right front wheels (front left and right wheels), 2L, 2R ... left and right rear wheels (rear left and right wheels), 3 ... engine, 4 ... generator, 5 ... motor, 6 ... speed reducer, 7 DESCRIPTION OF SYMBOLS ... Transmission, 8 ... Accelerator pedal, 9 ... Parking brake, 10 ... Controller, 10a ... e-4WD switch (switch), 11L, 11R ... Wheel speed detection sensor, 20 ... Mobile phone, 21L, 21R ... Wheel speed detection sensor , 31, engine speed detection sensor, 32, throttle opening detection sensor, 33, electronic control throttle, 71, shift position detection sensor, 81, accelerator opening sensor, 91, brake switch, 100, driving force control device

Claims (12)

  In a driving force control device for a four-wheel drive vehicle including a controller capable of controlling four-wheel drive, when the driver turns on a switch for instructing the controller to perform four-wheel drive, the controller After the accelerator is stepped on and the four-wheel drive vehicle starts running, monitoring of the wheel speeds of the front and rear, left and right wheels is started until it stops, and at least one of the front and rear wheels and the left and right wheels is monitored. If it is determined that the wheel speed difference is greater than or equal to a predetermined threshold value, four-wheel drive is performed, while it is determined that the wheel speed difference between the front and rear wheels and between the left and right wheels is smaller than the threshold value. In such a case, a driving force control device for a four-wheel drive vehicle, which performs two-wheel drive.   2. The driving force control apparatus for a four-wheel drive vehicle according to claim 1, wherein the controller determines in advance the number of repeated start and stop operations of the four-wheel drive vehicle even when the controller is performing four-wheel drive. When the wheel speed difference between the front and rear wheels and between the left and right wheels does not increase more than the threshold value continuously over the specified number of times, switch from four-wheel drive to two-wheel drive. A driving force control apparatus for a four-wheel drive vehicle.   3. The driving force control apparatus for a four-wheel drive vehicle according to claim 1 or 2, wherein the controller performs four-wheel drive immediately after starting the engine when the switch is ON. Vehicle driving force control device.   4. The driving force control apparatus for a four-wheel drive vehicle according to claim 3, wherein the controller continuously performs four-wheel drive for a predetermined time after the engine is started. Driving force control device for driving vehicle.   3. The driving force control apparatus for a four-wheel drive vehicle according to claim 1 or 2, wherein the controller connects a mobile phone capable of accessing via a network an information center storing weather information in each region. Provided with an interface, when the switch is ON, when the engine is started, the weather information in the travel region of the four-wheel drive vehicle is acquired from the information center via the mobile phone connected to the connection interface; A driving force control apparatus for a four-wheel drive vehicle, wherein it is determined whether to perform four-wheel drive or two-wheel drive when starting the engine based on the acquired weather information.   6. The driving force control apparatus for a four-wheel drive vehicle according to claim 5, wherein the controller includes information indicating snowfall in the travel area as the acquired weather information when the switch is ON. A four-wheel drive vehicle driving force control device that performs four-wheel drive when the engine is started.   In a driving force control method for a four-wheel drive vehicle capable of four-wheel drive, when the driver turns on a switch for instructing four-wheel drive, the four-wheel drive vehicle starts running and then stops. Start monitoring the wheel speeds of the front and rear, left and right wheels, and if the difference between at least one wheel speed between the front and rear wheels and the left and right wheels is greater than a predetermined threshold, On the other hand, when the wheel speed difference between the front and rear wheels and between the left and right wheels is smaller than the threshold value, the two-wheel drive is performed, and the driving force control method for a four-wheel drive vehicle is characterized.   8. The driving force control method for a four-wheel drive vehicle according to claim 7, wherein the number of repeated starting and stopping operations of the four-wheel drive vehicle is greater than a predetermined number of times even when four-wheel drive is being performed. When the wheel speed difference between the front and rear wheels and between the left and right wheels does not continuously increase beyond the threshold, the four-wheel drive is switched to the two-wheel drive. A driving force control method for a four-wheel drive vehicle.   9. The driving force control method for a four-wheel drive vehicle according to claim 7 or 8, wherein when the switch is ON, four-wheel drive is performed immediately after the engine is started. Control method.   The drive power control method for a four-wheel drive vehicle according to claim 9, wherein the four-wheel drive vehicle is continuously driven for a predetermined time after the engine is started. Force control method.   9. The driving force control method for a four-wheel drive vehicle according to claim 7 or 8, wherein when the switch is ON, an information center storing weather information in each region is accessed via a network when the engine is started. A mobile phone capable of acquiring weather information in the travel region of the four-wheel drive vehicle, and determining whether to perform four-wheel drive or two-wheel drive when starting the engine based on the acquired weather information. A driving force control method for a four-wheel drive vehicle, which is characterized.   12. The driving force control method for a four-wheel drive vehicle according to claim 11, wherein when the switch is ON, the acquired weather information includes information indicating snowfall in the travel area, and when the engine is started. A driving force control method for a four-wheel drive vehicle, wherein four-wheel drive is performed.

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