JP4840566B2 - Vehicle driving force distribution control device - Google Patents

Description

  The present invention relates to a driving force distribution control device for a vehicle, and particularly copes with a case where a vehicle is stopped for a short time, such as a transfer, a differential, etc., before the correction control by new sampling after the engine is started. The present invention relates to a driving force distribution control device for a vehicle that eliminates problems with the driving force transmission mechanism and the driving force distribution device.

  Some vehicles include a driving force distribution device that distributes driving force from an engine to main driving wheels and sub driving wheels in accordance with the traveling state of the vehicle.

Japanese Patent Publication No. 7-5033 Japanese Utility Model Publication No. 59-158757

  By the way, in the conventional vehicle driving force distribution control device, such as when an emergency tire is installed, when the tire pressure is reduced, the tire diameter is apparently reduced due to an increase in the number of passengers, etc. In the situation where the front and rear wheel rotational speed difference occurs, there is a disadvantage that the transfer, the differential and the like connected to the driving force distribution device may be damaged.

  It is necessary to perform control to eliminate this inconvenience.

  Conventionally, the front / rear differential rotation per 1 km / h of the vehicle speed is obtained for each control cycle, and the difference obtained by subtracting the average value and the standard deviation is multiplied by the vehicle speed to correct the front / rear differential rotation for different diameter tires. In some cases, a value obtained by subtracting the front-rear differential rotation correction amount from the front-rear wheel rotational speed difference is controlled as a front-rear differential rotation for control (Japanese Patent Laid-Open Nos. 2003-072407 and 2003-104079). Gazette, Japanese Patent Laid-Open No. 2003-200746, Japanese Patent Laid-Open No. 2003-226150).

  However, if the front and rear differential rotation correction amount for the different diameter of the tire is erased when the ignition switch is turned off, the correction starts to work after the ignition switch is turned on again and the engine is started while the tire remains in the different diameter state. If you run continuously for a shorter period of time (about 5 minutes), the front / rear rotation correction will not work at all, so it ’s the same as when you ’re driving with a large front / rear wheel rotational speed difference. There is a disadvantage that the transfer, the differential, etc. may be damaged.

  Further, in the conventional driving force distribution control device for a vehicle, when forward / backward differential rotation occurs, frictional heat is generated by a clutch in the driving force distribution device.

  In a state in which large forward / backward differential rotation continues, the amount of heat generated by friction increases, and there is a disadvantage that the driving force distribution device body may be damaged.

  In order to eliminate this inconvenience, control is performed such that the clutch heat generation amount is calculated from the transmission torque and the forward / backward differential rotation, and transmission is prohibited when a large amount of heat generation time has elapsed for a predetermined time (see Patent Document 2 above). To avoid damage.

However, if you don't remember the amount of heat when you turn off the ignition switch,
(1) Run with the side brakes forgotten to return, or do not easily escape from the stacked state, or perform operations that cause large forward / backward rotation.
(2) Turn off the ignition switch.
(3) Turn on the ignition switch immediately and run again with the side brakes forgotten to return, or it is difficult to escape from the stacked state, or an operation in which a large differential rotation occurs.

  Subsequently, when the above (2) and (3) are continuously performed, the calculated calorific value is “0 (also referred to as“ zero ”or“ zero ””) every time the ignition switch is turned on. Will be reset.

  As a result, a situation occurs in which the calculated heat generation amount does not reach the torque transmission prohibition heat generation amount even though the actual heat generation amount of the driving force distribution device exceeds the torque transmission prohibition heat generation amount. There is an inconvenience that the distribution device is destroyed.

The object of the present invention is that the controller stores the amount of heat generated even after the vehicle stops (“ignition switch off”). An object of the present invention is to realize a vehicle driving force distribution control device capable of performing drive distribution control using a large amount of heat generation .

Accordingly, in order to eliminate the above-described disadvantages, the present invention provides a vehicle driving force including a driving force distribution device that distributes the driving force from the engine to the main driving wheel and the sub driving wheel in accordance with the traveling state of the vehicle. The distribution control device includes transmission torque calculation means for calculating torque to be transmitted to the auxiliary drive wheels, and calculates a drive current for driving the driving force distribution apparatus according to the transmission torque calculated by the transmission torque calculation means. Drive current calculation means, and a rotation speed difference detection means for detecting a rotation speed difference between the main drive wheel and the sub drive wheel of the vehicle, and continues to supply power to the control device even after the ignition switch is turned off. And a shut-off means for shutting off the power supply to the control device after a predetermined time has elapsed, detected by the transmission torque calculated by the transfer torque calculating means and the rotational speed difference detecting means. A calorific value calculation means for calculating a calorific value from the difference in rotational speed between the main drive wheel and the sub drive wheel is provided, and the calorific value calculated by the calorific value calculation means during the execution of the shut-off means In particular, it is provided with a storage means for storing data in a nonvolatile memory capable of rewriting data.

As described above in detail, according to the present invention, even after the vehicle is stopped (which can be referred to as “ignition switch off”), the control device stores the heat generation amount. It is possible to carry out drive distribution control using an accurate calorific value close to the actual calorific value, and therefore stop the vehicle before the correction control by new sampling is performed after the engine starts. Even when such a short run is repeated, the amount of generated heat exceeds the limit value, and the driving force transmission mechanism such as transfer and differential and the driving force distribution device are not adversely affected.

As a result of the invention as described above, the control device stores the heat generation amount even after the vehicle stops, and the drive distribution using the accurate heat generation amount close to the actual heat generation amount at the time of the next run. Therefore, even if the vehicle is stopped for a short time before the correction control by new sampling is performed after the engine is started, the amount of generated heat is limited. The adverse effect on the driving force transmission mechanism such as transfer and differential and the driving force distribution device is avoided.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  1 to 6 show an embodiment of the present invention. In FIG. 2, reference numeral 1 denotes an FF-based four-wheel drive vehicle (hereinafter simply referred to as “vehicle”), and 2 denotes a driving force distribution control device for the vehicle 1.

  As shown in FIG. 2, the vehicle 1 has an engine 3 mounted on the front side and in a horizontally placed state, and a transmission 4, a front differential 5, and a transfer 6 are provided on the engine 3.

  Then, the front left drive shaft 7 and one end of the front right drive shaft 8 are connected to the front differential 5, the front left wheel 9 is attached to the other end of the front left drive shaft 7, and the front right drive shaft 8 is mounted. A front right wheel 10 is attached to the other end of the front side.

  Further, a driving force distribution device 12 is connected to the transfer 6 via a propeller shaft 11, and a rear differential 13 is provided in the driving force distribution device 12.

  Then, one end side of the rear left drive shaft 14 and the rear right drive shaft 15 is connected to the rear differential 13, and the rear left wheel 16 is attached to the other end side of the rear left drive shaft 14. A rear right wheel 17 is attached to the other end side of the right drive shaft 15.

  At this time, the driving force distribution device 12 applies the driving force from the engine 3 to the front left and right drive shafts 7 and 8 on the main driving wheel side and the rear left and right side on the auxiliary driving wheel according to the traveling state of the vehicle. It has a function of distributing to the drive shafts 14 and 15.

  That is, the output from the engine 3 is transmitted to the front left and right wheels 9 and 10 via the transmission 4, the front differential 5 and the front left and right drive shafts 7 and 8.

  A part of the torque input to the front differential 5 is transmitted to the rear wheel side by the transfer 6, and passes through the propeller shaft 11, the driving force distribution device 12, the rear differential 13, and the rear left and right drive shafts 14, 15. , Transmitted to the rear left and right wheels 16, 17.

  The driving force distribution device 12 is configured by an electronically controllable clutch and coil, etc., as in the prior art, and the fastening force of the driving force distribution device 12 is determined by a drive signal from the control device 18. The

Furthermore, the driving force distribution control device 2 includes a control device 18 and a transmission torque calculation means 19 that calculates torque to be transmitted to the rear left wheel 16 and the rear right wheel 17 that are the auxiliary driving wheels, In accordance with the transmission torque calculated by the transmission torque calculation means 19, a drive current calculation means 20 for calculating a drive current for driving the driving force distribution device 12 is provided, and the front left wheel 9 which is the main drive wheel of the vehicle. And a rotational speed difference detecting means 21 for detecting a rotational speed difference between the front right wheel 10 and the rear left wheel 16 and the rear right wheel 17 as the auxiliary driving wheels. A rotational speed difference correction amount calculating means 22 for calculating a rotational speed difference for the diameter tire is provided;
It has a configuration including a storage unit 24 that stores the correction amount calculated by the rotational speed difference correction amount calculation unit 22 in a nonvolatile memory in which data can be electrically rewritten.

  In this embodiment, the driving force distribution control device 2 includes a control device 18 and calculates a torque to be transmitted to the rear left wheel 16 and the rear right wheel 17 as the auxiliary driving wheels. A calculation means 19, a drive current calculation means 20 for calculating a drive current for driving the driving force distribution device 12 according to the transmission torque calculated by the transmission torque calculation means 19, and the main drive wheel of the vehicle; Rotational speed difference detecting means 21 for detecting a rotational speed difference between the front left wheel 9 and the front right wheel 10 as the rear driving wheel and the rear left wheel 16 and the rear right wheel 17 as the auxiliary driving wheels. The detecting means 21 includes a rotational speed difference correction amount calculating means 22 for calculating a rotational speed difference for tires of different diameters, and continues to supply power to the control device 18 even after the ignition switch is turned off. A shut-off means 23 for shutting off the power supply to the control device 18 after a lapse of a predetermined time is provided, and when the shut-off means 23 is executed, the correction amount calculated by the rotational speed difference correction amount calculating means 22 is electrically stored as data. The storage unit 24 stores data in a rewritable nonvolatile memory.

  More specifically, as shown in FIG. 2, the control device 18 includes a first rotational speed sensor 25 attached to the front left wheel 9, a second rotational speed sensor 26 attached to the front right wheel 10, and a rear side. A third rotational speed sensor 27 attached to the left wheel 16, a fourth rotational speed sensor 28 attached to the rear right wheel 17, a CAN (Local Area Network (LAN) standard) communication line, and a mode switch 29 is connected.

  At this time, the first to fourth rotational speed sensors 25, 26, 27, and 28 are obtained by diverting sensors of an anti-lock brake system (also referred to as “ABS”) provided in a normal four-wheel drive vehicle. Yes, outputs from the first to fourth rotation speed sensors 25, 26, 27, 28 are input to the control device 18.

Then, the rotational speeds of the front left wheel 9 and the front right wheel 10 as the main driving wheels (the input shaft rotational speed of the driving force distribution device 12) are obtained from the first and second rotational speed sensors 25 and 26 on the front side. Since the output shaft rotation speed of the driving force distribution device 12 can be obtained from the third and fourth rotation speed sensors 27 and 28 on the rear side, the rotation speed difference detecting means 21 is The rotational speed difference between the front left wheel 9 and the front right wheel 10 that are the main driving wheels of the vehicle and the rear left wheel 16 and the rear right wheel 17 that are the auxiliary driving wheels is detected by the equation.
Rotational speed difference (ΔN)
= Input shaft rotation speed of the driving force distribution device 12 -Output shaft rotation speed of the driving force distribution device 12

  Further, information such as engine speed and throttle opening required for controlling the current value output to the driving force distribution device 12 is input to the control means 18 from the CAN communication line.

  Further, the mode selector switch 29 has three modes: a 2WD mode, a 4WD-AUTO mode that is in a 4WD state only when a rotational speed difference occurs, and a 4WD-LOCK mode that is always in a 4WD state. Any one mode can be selected, and this switch signal is input to the control means 18.

  Furthermore, the correction amount stored in the storage means 24 is read immediately when the next ignition switch is turned on, and used when calculating the rotational speed difference correction amount.

  In other words, in the correction amount of the rotational speed difference due to the tires of different diameters, the driving current value that flows through the driving force distribution device 12 is various sensor information attached to the vehicle 1 (engine rotation, accelerator opening, vehicle speed, rotational speed). The torque to be transmitted to the rear wheel side is calculated from the difference and temperature) and the signal of the mode changeover switch 29, and is determined based on the “transmission torque-driving current characteristic” (see FIG. 3) determined in advance.

  Further, the torque transmitted to the rear wheels, that is, the rear left wheel 16 and the rear right wheel 17 that are auxiliary driving wheels, is generally a transmission torque corresponding to the accelerator opening determined in accordance with the accelerator opening. And the sum of the transmission torque determined in accordance with the rotation speed difference and the vehicle speed.

  As an example of how to determine the amount of transmission torque corresponding to the accelerator opening, it is determined from the accelerator coefficient obtained from the “accelerator coefficient-vehicle speed characteristic” shown in FIG. 4 and the “transmission torque-accelerator opening characteristic” shown in FIG. It is obtained as a value multiplied by the transmission torque.

  As an example of how to obtain the transmission torque determined in accordance with the rotational speed difference and the vehicle speed, the rotational speed difference and the vehicle speed are applied to a transmission torque map composed of “transmission torque-vehicle speed characteristics” shown in FIG. Torque can be obtained.

  Furthermore, when the tires have different diameter differences, the rotational speed difference due to the different diameter differences is always added as an offset, so that the transmission torque determined according to the rotational speed difference and the vehicle speed increases. Then, the extra transmission torque generated due to the difference in the different diameters is always transmitted to the rear left wheel 16 and the rear right wheel 17 which are the auxiliary drive wheels, so that the fuel consumption is deteriorated and the load on the drive system is increased. It will be.

  Therefore, generally, 4WD control is performed using a rotational speed difference obtained by subtracting the correction amount of the rotational speed difference caused by the difference in tire diameter.

However, in the case of the "Erase correction amount when turning off the ignition switch" measure, the tires still have different diameter differences,
(1) The ignition switch is turned on and the engine 3 is started.
(2) Start running at medium to high speed, and turn off the ignition switch before starting the correction of the rotational speed difference due to the tire diameter difference.
When the above (1) and (2) are continuously performed (in other words, when the traveling pattern of (1) and (2) is repeated), the rotation is started from the start of traveling. Since it takes several minutes until the speed difference correction starts to work, there is a possibility that the transfer, the differential, etc. may be damaged, almost the same as the situation where the vehicle is running without any rotational speed difference correction control.

  In order to avoid such a situation, the correction amount is stored in another recording medium (an EEPROM or other storage medium that does not disappear even if the battery is removed) from when the ignition switch is turned off until the self-shutoff is completed. In the first routine when the ignition switch is turned on next time, the correction amount is read from the storage medium and used in the control, so that the rotational speed difference correction control is always activated, and the drive system such as transfer and differential is protected. Is intended.

  The driving force distribution control device 2 includes a control device 18 and transmission torque calculation means 19 that calculates torque to be transmitted to the rear left wheel 16 and the rear right wheel 17 that are the auxiliary driving wheels. In accordance with the transmission torque calculated by the transmission torque calculation means 19, a drive current calculation means 20 for calculating a drive current for driving the driving force distribution device 12 is provided, and the front left wheel 9 which is the main drive wheel of the vehicle. And a rotational speed difference detecting means 21 for detecting a rotational speed difference between the front right wheel 10 and the rear left wheel 16 and the rear right wheel 17 as the auxiliary driving wheels, and calculated by the transmission torque calculating means 19. The front left wheel 9 and the front right wheel 10 which are the main driving wheels detected by the transmission torque and the rotational speed difference detecting means 21 and the rear left wheel 16 and the rear right wheel 17 which are the auxiliary driving wheels. The heat generation amount calculation means 30 for calculating the heat generation amount from the difference in rotational speed of the two, and the storage means for storing the heat generation amount calculated by the heat generation amount calculation means 30 in an electrically rewritable nonvolatile memory 24 is also provided.

  In this embodiment, the driving force distribution control device 2 includes a control device 18 and a transmission torque calculation means for calculating torque transmitted to the rear left wheel 16 and the rear right wheel 17 which are the auxiliary driving wheels. 19, comprising drive current calculation means 20 for calculating a drive current for driving the drive force distribution device 12 according to the transmission torque calculated by the transmission torque calculation means 19, which is the main drive wheel of the vehicle. Rotational speed difference detecting means 21 for detecting a rotational speed difference between the front left wheel 9 and the front right wheel 10 and the rear left wheel 16 and the rear right wheel 17 as the auxiliary driving wheels is provided, and after turning off the ignition switch Is also provided with a shut-off means 23 for continuing the power supply to the control device 18 and shutting off the power supply to the control device 18 after a predetermined time elapses. The rotation of the front left wheel 9 and the front right wheel 10 which are the main driving wheels detected by the transmission torque and the rotation speed difference detecting means 21 and the rear left wheel 16 and the rear right wheel 17 which are the auxiliary driving wheels. A calorific value calculating means 30 for calculating the calorific value from the speed difference is provided, and the calorific value calculated by the calorific value calculating means 30 can be electrically rewritten when the blocking means 23 is executed. Having a storage means 24 for storing in the memory.

  Then, the calorific value stored in the storage unit 24 is read immediately when the next ignition switch is turned on, and then compared with a set value. When the read calorific value is larger than the set value, In this case, it is prohibited to transmit torque to the rear left wheel 16 and the rear right wheel 17 which are auxiliary driving wheels.

  In other words, when a difference in rotational speed occurs in the amount of heat generated by the driving force distribution device 12, frictional heat is generated by the clutch in the driving force distribution device 12. In a state where a large rotational speed difference is continuously generated, the heat generation amount may exceed the limit heat generation amount of the driving force distribution device 12 and may be damaged.

  Therefore, the clutch heat generation amount is calculated from the difference between the transmission torque and the rotational speed, and when the time during which the heat generation amount is large has elapsed for a predetermined time, control is performed to prohibit torque transmission (see Patent Document 2) to avoid damage. It was.

  However, as an example of when the amount of heat generated is not memorized when the ignition switch is turned off, in a situation where it is difficult to escape from the stack, etc., after the operation that suddenly generates heat, the ignition switch is turned off. If the ignition switch is turned on immediately and suddenly generates heat again, the amount of heat generated is reset to “0” when the ignition switch is turned off to on. The calorific value is larger than the calorific value obtained from the calculation.

  Therefore, the actual heat generation amount of the driving force distribution device 12 exceeds the heat generation amount prohibiting torque transmission, and the calculated heat generation amount is equal to or less than the heat generation amount prohibiting torque transmission. .

  At this time, if the driving is performed such that the heat is further abruptly generated, the driving force distribution device 12 is damaged beyond the limit heat generation amount, and the vehicle cannot run.

  In order to avoid such a situation, the amount of heat generated is stored in another recording medium (an EEPROM or other storage medium that does not disappear even if the battery is removed) between the time when the ignition switch is turned off and the time when self-shutoff ends. Next, when the ignition switch is turned on, the amount of heat generated from the drive force distribution device 12 is actually calculated by reading out the amount of heat generated from the storage medium in the first routine when the ignition switch is turned on and using it in the control. And avoiding breakage of the driving force distribution device 12 due to heat generation.

  However, the calorific value stored in the storage means 24 may be a value obtained by reducing the set calorific value from the value of the calorific value immediately before the ignition switch is turned off.

  In other words, taking into account the long off time of the ignition switch, the heat generation amount stored in another storage medium is reduced by a preset value from the heat generation amount when the ignition switch is off as shown in FIG. It may be a value. As a result, since the vehicle state immediately before the stop has a large amount of heat generation, even when the vehicle stops in the 2WD state, the value of the heat generation amount stored in another recording medium is reduced by a preset ratio. Will be saved. Therefore, when the ignition switch is turned on next time, a value lower than the threshold value for selecting either 2WD or 4WD is read as the heat generation amount, so that the 4WD state is set. Therefore, since the driving state selected by the driver can be realized for a longer time without damaging the driving mechanism, it is possible to contribute to improving the product power. FIG. 8 shows a case where the reduced value is not stored for comparison with FIG. For example, a value obtained by reducing 30% from the amount of heat generated when the ignition switch is turned off may be stored.

  Next, the operation will be described along the control flowchart of the driving force distribution control device 2 of FIG.

  When the control program of the driving force distribution control device 2 starts (A01), the process proceeds to determination (A02) as to whether or not the ignition switch that is determination 1 is ON (also referred to as “ON”). When the determination (A02) is YES, after the ignition switch that is determination 2 is turned on, the routine proceeds to determination (A03) as to whether or not it is the first routine. When the determination (A02) is NO, The process proceeds to determination 3 (A04) as to whether self-shutoff is in progress.

  In the determination (A03) of whether or not the routine is the first routine after turning on the ignition switch which is the above determination 2, if this determination (A03) is YES, the correction amount read from the storage medium In addition, a process (A05) for converting the heat generation amount into a heat generation amount read from the storage medium is performed, and a sensor or CAN including the first to fourth rotation speed sensors 25, 26, 27, 28 attached to the vehicle 1 When the process proceeds to processing (A06) for acquiring data from the communication line and the determination (A03) is NO, the first to fourth rotational speed sensors 25, 26, 27, and 28 attached to the vehicle 1 are included. The process directly moves to the process (A06) for acquiring data from the sensor or the CAN communication line.

And after the process (A06) which acquires data from the sensor and CAN communication line which contain the said 1st-4th rotational speed sensors 25, 26, 27, 28 attached to the vehicle 1, four 1st-1st 4 From the rotational speed sensors 25, 26, 27, 28
= Rotation speed difference (also referred to as “front-rear differential rotation”) (ΔN) is calculated using the input shaft rotation speed of the driving force distribution device 12−output shaft rotation speed of the driving force distribution device 12, and the correction amount is subtracted. Processing (A07) is performed, and the processing shifts to processing (A08) in which the rotational speed difference due to the different diameter degree of the tire is recalculated and the correction amount is updated.

After the calculation (A08) for recalculating the rotational speed difference due to the different diameter of the tire and updating the correction amount, the mode change switch 29, the vehicle speed, the rotational speed difference (ΔN), the engine speed, the accelerator speed, etc. The process of calculating the torque transmitted to the rear wheel side (A09) from the above information is performed, and the formula: heat generation amount = transmission torque X rotational speed difference (ΔN)
The process proceeds to the process (A10) for obtaining the heat generation amount.

Also, the formula Heat generation amount = Transmission torque X Rotational speed difference (ΔN)
After the process (A10) for obtaining the heat generation amount by the above, a process (A11) for calculating the drive current value is performed by applying the torque transmitted to the rear wheel side to the “transmission torque-drive current characteristic” shown in the figure, and the determination 4 The process proceeds to judgment (A12) as to whether or not the heat generation amount exceeds the torque transmission prohibition heat generation amount.

  If the determination (A12) is YES in the determination (A12) as to whether or not the heat generation amount as the determination 4 exceeds the torque transmission prohibition heat generation amount, the process of setting the drive current value to “0” (A13) The process proceeds to the process (A14) for outputting the drive current value, and when the determination (A12) is NO, the process directly proceeds to the process (A14) for outputting the drive current value.

Further, when the determination (A04) is YES in the determination 3 (S04), which is the determination 3 described above, if the determination (A04) is YES, the following two (1) rotational speed difference corrections for different diameter tires are performed. Amount (2) When the process (A15) for saving the heat generation amount of the driving force distribution device 12 to the storage medium is performed, the process proceeds to a process (A14) for outputting the drive current value, and the determination (A04) is NO To the end of the control program (A16).

  And after the process (A14) which outputs a drive current value, it transfers to the end (A16) of the program for control of the said driving force distribution control apparatus 2. FIG.

  The above-described flowchart may be executed and processed repeatedly by the control device (also referred to as “CPU”) 18 at predetermined intervals.

  Accordingly, the control device 18 is provided, and further includes transmission torque calculation means 19 for calculating torque to be transmitted to the rear left wheel 16 and the rear right wheel 17 which are the auxiliary drive wheels. Drive current calculation means 20 for calculating a drive current for driving the drive force distribution device 12 according to the calculated transmission torque is provided, and the front left wheel 9 and the front right wheel 10 which are the main drive wheels of the vehicle and the A rotational speed difference detecting means 21 for detecting a rotational speed difference between the rear left wheel 16 and the rear right wheel 17 which are auxiliary driving wheels is provided, and the rotational speed difference detecting means 21 provides a rotational speed difference for different diameter tires. The rotational speed difference correction amount calculating means 22 for calculating the rotational speed difference correction means 22 is stored, and the correction amount calculated by the rotational speed difference correction amount calculating means 22 is stored in a nonvolatile memory capable of electrically rewriting data. Since the control device 18 always stores the correction amount calculated by the rotational speed difference correction amount calculation means by the driving force distribution control device 2 having the configuration including the storage means 24, a new value is generated every time the engine is started. There is no need to implement correction control by sampling.

  The control device 18 includes a transmission torque calculation means 19 for calculating torque transmitted to the rear left wheel 16 and the rear right wheel 17 which are the auxiliary drive wheels, and is calculated by the transmission torque calculation means 19. Drive current calculation means 20 for calculating a drive current for driving the drive force distribution device 12 according to the transmitted torque, and the front left wheel 9 and the front right wheel 10 which are the main drive wheels of the vehicle, Rotational speed difference detection means 21 for detecting the rotational speed difference between the rear left wheel 16 and the rear right wheel 17 which are drive wheels is provided, and the rotational speed difference detection means 21 is used to determine the rotational speed difference for different diameter tires. A rotation speed difference correction amount calculating means 22 for calculating is provided, and power supply to the control device 18 is continued even after the ignition switch is turned off, and power supply to the control device 18 is cut off after a predetermined time has elapsed. And a storage means for storing the correction amount calculated by the rotational speed difference correction amount calculation means 22 in a nonvolatile memory capable of electrically rewriting data. After the vehicle is stopped by the driving force distribution control device 2 having a configuration including 24, the control device 18 stores data of correction values based on the rotational speed difference for different diameter tires. Therefore, it is possible to immediately execute the drive distribution control in consideration of the rotational speed difference for the tires of different diameters. Therefore, before the correction control by new sampling is performed after the engine 3 is started, the vehicle 1 is Even when the vehicle is stopped for a short time such as when it stops, it will not overload the driving force transmission mechanism such as transfer and differential, and the driving force distribution device. Thus it is possible to realize a highly reliable driving force distribution control device 2.

  Further, the correction amount stored in the storage means 24 is read out immediately when the next ignition switch is turned on, and is used when calculating the rotational speed difference correction amount, so that it is necessary to determine the transmission torque. When calculating the rotational speed difference, the rotational speed difference data for tires with different diameters can be read immediately after the ignition switch is turned on, and the accurate rotational speed difference can be immediately grasped. Driving force distribution control can be always realized.

  Furthermore, the control device 18 includes a transmission torque calculation means 19 for calculating torque to be transmitted to the rear left wheel 16 and the rear right wheel 17 as the auxiliary drive wheels. Drive current calculation means 20 for calculating a drive current for driving the drive force distribution device 12 according to the calculated transmission torque is provided, and the front left wheel 9 and the front right wheel 10 which are the main drive wheels of the vehicle and the Rotational speed difference detection means 21 for detecting a rotational speed difference between the rear left wheel 16 and the rear right wheel 17 which are auxiliary driving wheels is provided, and the transmission torque calculated by the transmission torque calculation means 19 and the rotational speed difference. From the difference in rotational speed between the front left wheel 9 and front right wheel 10 that are the main drive wheels detected by the detection means 21 and the rear left wheel 16 and rear right wheel 17 that are the sub drive wheels. The heat generation amount calculation means 30 for calculating the amount of heat, and the storage means 24 for storing the heat generation amount calculated by the heat generation amount calculation means 30 in a nonvolatile memory capable of electrically rewriting data. Since the control device 18 always stores the heat generation amount calculated by the heat generation amount calculation means by the driving force distribution control device 2, it is not necessary to perform correction control by new sampling every time the engine is started.

  The control device 18 includes a transmission torque calculation means 19 for calculating torque transmitted to the rear left wheel 16 and the rear right wheel 17 which are the auxiliary drive wheels, and is calculated by the transmission torque calculation means 19. Drive current calculation means 20 for calculating a drive current for driving the drive force distribution device 12 according to the transmitted torque, and the front left wheel 9 and the front right wheel 10 which are the main drive wheels of the vehicle, Rotational speed difference detecting means 21 for detecting a rotational speed difference between the rear left wheel 16 and the rear right wheel 17 as drive wheels is provided, and power supply to the control device 18 is continued even after the ignition switch is turned off. A shut-off means 23 for shutting off the power supply to the control device 18 after elapse of a predetermined time is provided. The generated heat is calculated from the difference in rotational speed between the front left wheel 9 and front right wheel 10 that are the main driving wheels and the rear left wheel 16 and rear right wheel 17 that are the auxiliary driving wheels. And a storage unit 24 for storing the heat generation amount calculated by the heat generation amount calculation unit 30 in a nonvolatile memory capable of electrically rewriting data when the blocking unit 23 is executed. Even after the vehicle is stopped by the driving force distribution control device 2 having the configuration, since the control device 18 stores the heat generation amount, an accurate heat generation amount close to the actual heat generation amount was used in the next travel. The drive distribution control can be performed, and therefore, when the vehicle 1 is stopped for a short time before the correction control by the new sampling is performed after the engine is started. Heating value is exceeded the limit value, the transfer, the driving force transmission mechanism and the like differential, it does not adversely affect the driving force distribution device 12.

  Further, the calorific value stored in the storage means 24 is read out immediately when the next ignition switch is turned on, and then compared with a set value. When the read calorific value is larger than the set value, Because it is prohibited to transmit torque to the auxiliary drive wheels, the control device can grasp the data corresponding to the actual heat generation immediately after starting, and transfer the driving force such as transfer, differential, etc. It is possible to improve the accuracy of the system that protects the mechanism and the driving force distribution device 12.

  Furthermore, the calorific value stored in the storage means 24 is a value obtained by subtracting a set ratio from the value of the calorific value immediately before the ignition switch is turned off, so that the vehicle state immediately before the stop has a large calorific value. Even when the vehicle stops in the 2WD state, a value reduced by a preset ratio is stored as the value of the heat generation amount stored in another recording medium. Therefore, when the ignition switch is turned on next time, a value lower than the threshold value for selecting either 2WD or 4WD is read as the heat generation amount, so that the 4WD state is set. Therefore, since the driving state selected by the driver can be realized for a longer time without damaging the driving mechanism, it is possible to contribute to improving the product power.

It is a flowchart for control of the driving force distribution control apparatus which shows the Example of this invention. It is a system diagram of a driving force distribution control device for a vehicle. It is a figure which shows the transmission torque-drive current characteristic. It is a figure which shows an accelerator coefficient-vehicle speed characteristic. It is a figure which shows the transmission torque-accelerator opening degree characteristic. It is a figure which shows the transmission torque-vehicle speed characteristic. It is a figure which shows the emitted-heat amount at the time of ignition switch OFF, and a relationship with time. It is a figure which shows the emitted-heat amount and time in the case of not storing the reduced value.

1 Four-wheel drive vehicle (hereinafter simply referred to as “vehicle”)
2 Driving force distribution control device 3 Engine 4 Transmission 5 Front differential 6 Transfer 7 Front left drive shaft 8 Front right drive shaft 9 Front left wheel 10 Front right wheel 11 Propeller shaft 12 Driving force distribution device 13 Rear differential 14 Rear left drive shaft DESCRIPTION OF SYMBOLS 15 Rear right drive shaft 16 Rear left wheel 17 Rear right wheel 18 Control apparatus 19 Transmission torque calculation means 20 Drive current calculation means 21 Rotational speed difference detection means 22 Rotational speed difference correction amount calculation means 23 Shut off means 24 Storage means 25 First Rotational Speed Sensor 26 Second Rotational Speed Sensor 27 Third Rotational Speed Sensor 28 Fourth Rotational Speed Sensor 29 Mode Change Switch 30 Heat Generation Amount Calculation Means

Claims (3)

In a vehicle driving force distribution control device including a driving force distribution device that distributes driving force from an engine to main driving wheels and sub driving wheels according to the traveling state of the vehicle, torque transmitted to the sub driving wheels is transmitted. A transmission torque calculation means for calculating, and a drive current calculation means for calculating a drive current for driving the driving force distribution device according to the transmission torque calculated by the transmission torque calculation means; A rotation speed difference detecting means for detecting a difference in rotation speed between the auxiliary drive wheel and the auxiliary drive wheel, the power supply to the control device is continued even after the ignition switch is turned off, and the power supply to the control device is cut off after a predetermined time has elapsed. A blocking means, and a transmission torque calculated by the transmission torque calculation means and a rotation speed difference between the main drive wheel and the sub drive wheel detected by the rotation speed difference detection means. A storage unit that includes a calorific value calculation unit that calculates a calorific value, and that stores the calorific value calculated by the calorific value calculation unit in a nonvolatile memory that is electrically rewritable when the shut-off unit is executed; driving force distribution control device for a vehicle, characterized in that it comprises. The calorific value stored in the storage means is read immediately when the next ignition switch is turned on, and then compared with a set value.If the read calorific value is greater than the set value, driving force distribution control device for a vehicle according to claim 1, characterized in that prohibits to transmit torque to the secondary drive wheels. 3. The vehicle driving force distribution control device according to claim 2 , wherein the heat generation amount stored in the storage means is a value obtained by reducing a set amount from a heat generation amount immediately before the ignition switch is turned off. .

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