JP4810253B2 - Control device for four-wheel drive vehicle - Google Patents

Description

  The present invention relates to a four-wheel drive that changes the distribution of driving force when a puncture of a wheel is detected in a four-wheel drive vehicle including a driving force distribution device that can change the distribution of driving force between front and rear wheels and left and right wheels. The present invention relates to a vehicle control device.

  Since it is not preferable to travel in a state where the tire air pressure of the vehicle is lowered to some extent, various tire air pressure determination devices have been proposed. For example, the tire pressure is detected by a sensor and the decrease in the tire pressure is determined, or when the tire pressure decreases, the number of rotations of the wheel with the decreased air pressure increases. There has been proposed a wheel speed sensor that detects a decrease in tire air pressure based on the wheel speed detected by the wheel speed sensor.

  For example, in the tire air pressure determination device disclosed in Japanese Patent Application Laid-Open No. 63-305011, the output from the wheel speed sensors of four wheels is used to calculate the sum of the wheel speeds of a pair of wheels on a diagonal line, When the difference from the sum of the wheel speeds of the pair of wheels on the diagonal is equal to or greater than a predetermined value, it is determined that the tire air pressure of one of the pair of wheels having the larger total wheel speed has decreased.

  Then, when the larger wheel speed of the pair of wheels is larger than the average value of the wheel speeds of the four wheels by a predetermined value or more, it is determined that the air pressure of the wheels has decreased, and the determination result Is output to the alarm device.

Japanese Patent Laid-Open No. 6-286436 includes a differential limiting device that can be switched between a locked state and an unlocked state, and a tire air pressure determining device that detects an abnormality in the tire air pressure of the wheel and outputs an alarm. Further, there is disclosed a vehicle control device characterized in that the vehicle is provided with switching control means for receiving a tire pressure abnormality determination from the tire air pressure determination device and switching the differential limiting device to a locked state.
JP 63-305011 A JP-A-6-286436

  In a conventional four-wheel drive vehicle, since a driving force distribution device is not generally mounted, even if tire puncture is detected, no special control is performed, or as disclosed in Patent Document 2, The control only switches the differential limiting device to the locked state in response to the detection of the tire puncture, and it is impossible to carry out appropriate drive force distribution control.

  When the tire of the vehicle is punctured, the running resistance of the punctured wheel is increased, and thus the running stability is lowered. Provided is a control device for a four-wheel drive vehicle that appropriately controls the amount of driving force distribution according to the air pressure of a punctured tire, especially when the tire is punctured while traveling on an expressway. Is needed.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a control device for a four-wheel drive vehicle that appropriately controls a drive force distribution amount in accordance with a change in air pressure of a punctured tire. Is to provide.

  According to the first aspect of the present invention, the driving power source includes a pair of main driving wheels always connected to the driving source and a pair of slave driving wheels driven by the driving source via the driving force distribution device. A control device for a four-wheel drive vehicle capable of allocating driving force between the main drive wheel and the slave drive wheel and between the left and right slave drive wheels by the distribution device, the driving state detection means for detecting the driving state of the vehicle, First and second air pressure detecting means for detecting air pressure of the pair of main drive wheels, and air pressure comparing means for comparing a predetermined threshold value of the wheel air pressure with the air pressure detected by the first and second air pressure detecting means; Air pressure abnormality detecting means for detecting a main drive wheel having an air pressure equal to or lower than the threshold value based on an output of the air pressure comparison means; and a pair of main drive wheels based on outputs of the first and second air pressure detection means. Air pressure ratio calculation to calculate air pressure ratio And when the air pressure abnormality is detected by the air pressure abnormality detecting means, the driving force distribution device according to the vehicle operating state detected by the operating state detecting means and the air pressure ratio calculated by the air pressure ratio calculating means There is provided a control device for a four-wheel drive vehicle, comprising: a control means for changing the driving force distribution amount.

  According to a second aspect of the present invention, in the first aspect of the invention, the control means is a main drive in which an abnormality in air pressure is detected by the air pressure abnormality detecting means in the vehicle operating state detected by the driving state detecting means. When the vehicle is turning to the wheel side, the distribution of the driving force of the slave drive wheel on the opposite side of the master drive wheel where the air pressure abnormality is detected is set to the same value as the slave drive wheel on the same side as the main drive wheel where the air pressure abnormality is detected. There is provided a control device for a four-wheel drive vehicle, characterized in that control is performed so as to be larger than a drive force distribution amount distributed to drive wheels.

  According to a third aspect of the present invention, in the first aspect of the invention, the control means is a main drive in which an abnormality in air pressure is detected by the air pressure abnormality detecting means in the vehicle operating state detected by the driving state detecting means. When the vehicle is turning to the opposite side of the wheel, the air pressure abnormality detecting means abnormally detects the driving force distribution amount of the driven wheel on the same side as the main driving wheel where the air pressure abnormality is detected by the air pressure abnormality detecting means. There is provided a control device for a four-wheel drive vehicle, which is controlled so as to be larger than a drive force distribution amount of a slave drive wheel on the opposite side of the main drive wheel in which is detected.

  According to a fourth aspect of the present invention, in the first aspect of the invention, when the driving state of the vehicle detected by the driving state detecting unit is a straight traveling state, the control unit uses the air pressure abnormality detecting unit. Four-wheel control, wherein the drive force distribution amount of the slave drive wheel on the same side as the primary drive wheel side in which an abnormality in air pressure is detected is controlled to be larger than the drive force distribution amount of the slave drive wheel on the opposite side A drive vehicle control device is provided.

  According to the fifth aspect of the present invention, the driving power source includes a pair of main driving wheels always connected to the driving source, and a pair of slave driving wheels driven by the driving source via the driving force distribution device. A control device for a four-wheel drive vehicle capable of allocating driving force between the main drive wheel and the slave drive wheel and between the left and right slave drive wheels by the distribution device, the driving state detection means for detecting the driving state of the vehicle, First and second air pressure detecting means for detecting the air pressure of the pair of driven wheels, and an air pressure comparing means for comparing a predetermined threshold value of the wheel air pressure with the air pressure detected by the first and second air pressure detecting means; Air pressure abnormality detecting means for detecting a driven wheel whose air pressure is equal to or lower than the threshold value based on the output of the air pressure comparing means; and the pair of driven wheels based on the outputs of the first and second air pressure detecting means. Air pressure ratio calculation to calculate air pressure ratio And when the air pressure abnormality is detected by the air pressure abnormality detecting means, the driving force distribution device according to the vehicle operating state detected by the operating state detecting means and the air pressure ratio calculated by the air pressure ratio calculating means There is provided a control device for a four-wheel drive vehicle, comprising: a control means for changing the driving force distribution amount.

  According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the control means is a driven wheel in which the operating state of the vehicle detected by the operating state detecting means detects an abnormality in air pressure by the air pressure abnormality detecting means. When the vehicle is turning to the side, the driving force distribution amount of the slave drive wheel on the opposite side to the slave drive wheel on which the air pressure abnormality is detected by the air pressure abnormality detection means is the same as that of the slave drive wheel on which the air pressure abnormality is detected. There is provided a control device for a four-wheel drive vehicle, characterized in that the control is performed so as to be larger than a driving force distribution amount.

  According to a seventh aspect of the present invention, in the fifth aspect of the present invention, the control means is a driven wheel in which the operating state of the vehicle detected by the operating state detecting means detects an abnormal air pressure by the air pressure abnormality detecting means. When the vehicle is turning to the opposite side, the drive force distribution amount of the driven wheel that has detected an abnormality in air pressure by the air pressure abnormality means is larger than the drive force distribution amount of the opposite drive wheel on the opposite side. A control device for a four-wheel drive vehicle is provided.

  According to an eighth aspect of the present invention, in the fifth aspect of the present invention, when the vehicle driving state detected by the driving state detecting unit is a straight traveling state, the control unit uses the air pressure abnormality detecting unit. Provided is a control device for a four-wheel drive vehicle, wherein the drive force distribution amount of a slave drive wheel in which an abnormality in air pressure is detected is controlled to be larger than the drive force distribution amount of a slave drive wheel on the opposite side Is done.

  According to the first to fourth aspects of the present invention, when any of the main driving wheels is punctured, the amount of driving force distributed to the left and right driven wheels can be appropriately controlled according to the driving state. The running stability can be secured by suppressing the running stability from being lowered due to the deformation.

  According to the fifth to eighth aspects of the present invention, when any of the driven wheels is punctured, the driving force distribution amount distributed to the left and right driven wheels can be appropriately controlled according to the driving state. The running stability can be secured by suppressing the running stability from being lowered due to the deformation.

  Referring to FIG. 1, there is shown a schematic diagram of a power transmission device for a four-wheel drive vehicle based on a front engine / front drive (FF) vehicle to which the control device of the present invention can be applied.

  As shown in FIG. 1, the power transmission system includes a front differential device 6 in which power from an engine 2 disposed in front of the vehicle is transmitted from an output shaft 4 a of a transmission 4, and power from the front differential device 6 is transferred to a transfer 7. And a speed increasing device (transmission device) 10 transmitted through the propeller shaft 8 and a rear differential device 12 to which power from the speed increasing device 10 is transmitted.

  The front differential device 6 has a conventionally known structure, and power from the output shaft 4a of the transmission 4 is transmitted to the left and right front wheel drive shafts (axles) 20 via a plurality of gears 14 and output shafts 16 and 18 in the differential case 6a. , 22, the left and right front wheels 21, 23 are driven.

  As will be described later, the rear differential device 12 includes a pair of planetary gear sets and a pair of electromagnetic actuators for controlling the fastening of the multi-plate brake mechanism, and controls the electromagnetic actuators to control the left and right rear wheel drive shafts. (Axles) By transmitting power to 24 and 26, the left and right rear wheels 25 and 27 are driven.

  Each of the front wheels 21 and 23 and the rear wheels 25 and 27 is provided with air pressure sensors 5a, 5b, 5c and 5d for detecting tire air pressure. Outputs of these air pressure sensors 5 a to 5 d are input to an electronic control unit (ECU) 11. Further, the output of the steering angle sensor 9 that detects the steering angle of the steering wheel (steering wheel) is also input to the ECU 11.

  FIG. 2 is a cross-sectional view of the speed increasing device (transmission device) 10 and the rear differential device 12 disposed on the downstream side of the speed increasing device 10. The speed increasing device 10 includes an input shaft 30 rotatably mounted in a casing 28 and an output shaft (hypoid pinion shaft) 32.

  The speed increasing device 10 further includes an oil pump subassembly 34, a planetary carrier subassembly 38, a direct coupling clutch subassembly 40, and a speed change brake 42.

  The rear differential device 12 provided on the downstream side of the speed increasing device 10 has a hypoid pinion gear 44 formed at the tip of the hypoid pinion shaft 32. The hypoid pinion gear 44 meshes with the hypoid ring gear 48, and the power from the hypoid ring gear 48 is input to the ring gears of the planetary gear sets 50A and 50B provided on the left and right.

  The sun gears of the planetary gear sets 50 </ b> A and 50 </ b> B are attached so as to be rotatable around the left rear axle 24 and the right rear axle 26. The planetary carriers of the planetary gear sets 50A and 50B are fixed to the left rear axle 24 and the right rear axle 26. A planet gear carried on the planetary carrier meshes with the sun gear and the ring gear.

  The left and right planetary gear sets 50A and 50B are coupled to a brake mechanism 51 provided for variably controlling the torque of the sun gear. The brake mechanism 51 includes a wet multi-plate brake 52 and an electromagnetic actuator 56 that operates the multi-plate brake 52.

  A plurality of brake plates of the wet multi-plate brake 52 are fixed to the casing 54, and a plurality of brake disks arranged alternately with the brake plates are fixed to the sun gears of the planetary gear sets 50A and 50B.

  The electromagnetic actuator 56 is opposed to the ring-shaped core (yoke) 58 having an annular groove, the annular solenoid (annular excitation coil) 60 inserted into the annular groove of the ring-shaped core 58, and the ring-shaped core 58 with a predetermined gap. And a ring-shaped piston 64 connected to the armature 62.

  When a current is applied to the solenoid 60, the armature 62 is attracted to the core 58 by the electromagnetic force formed by the solenoid 60 and a thrust is generated. Due to this thrust, the piston 64 integrally connected to the armature 62 presses the multi-plate brake 62, thereby generating a brake torque.

  As a result, the sun gears of the planetary gear sets 50A and 50B are fixed to the casing 54, respectively, and the driving force of the hypoid pinion shaft 32 is applied to the left and right rear axles 24, via the ring gear, planet gear, and planetary carrier of the planetary gear sets 50A and 50B. 26.

  By controlling the current flowing through the annular solenoid 60, the driving force of the input shaft 30 can be arbitrarily distributed to the left and right rear axles 24, 26 in a directly connected state or increased by the speed increasing device 10. Turning control can be realized.

  When the shift brake 42 is off, the direct coupling clutch 40 is engaged by the biasing force of the coil spring. Therefore, the power of the input shaft 30 is output to the output shaft (hypoid pinion shaft) 32 as it is.

  On the other hand, when turning at a corner having a small turning radius in the four-wheel drive traveling state in the middle / low speed range, the shift brake 42 is engaged and the engagement of the direct clutch 40 is released. In this state, the planetary carrier assembly 38 becomes a gear train having a certain speed change ratio, and a speed change (acceleration) is established between the input shaft 30 and the output shaft (hypoid pinion shaft) 32. The speed increasing ratio is set to 1.07, for example.

  Assume that the vehicle turns left as shown in FIG. 3 in a state where the output shaft 32 is accelerated with respect to the input shaft 30. At this time, more current flows through the right solenoid 60 of the rear differential device 12 than the left solenoid 60, and the right brake mechanism 51 is tightened more strongly than the left.

  Thereby, the driving force of the output shaft 32 is largely distributed to the right rear axle 26, and as shown by the arrow F4 in FIG. 3, the rear wheel driving torque on the outer side of the turn can be made larger than the rear wheel driving torque on the inner side of the turning. For example, the turning performance in the middle / low speed range can be improved. Conversely, the rear wheel drive torque inside the turn can be made larger than the rear wheel drive torque outside the turn, thereby obtaining stability in a high speed range.

  In this way, by controlling the value of the current flowing through the left and right solenoids 60, the driving force of the input shaft 30 is increased in the directly connected state or with the speed increasing device 10, and is arbitrarily distributed to the left and right rear axles 24, 26. Therefore, it is possible to achieve optimum turning control and / or facilitation of smoldering escape.

  Switching from the direct connection state to the acceleration state is controlled as follows, for example. A threshold is set for the vehicle speed, and when the steering force or the steering angle exceeds the threshold, the speed increasing device 10 is controlled to be in a speed increasing state.

  The rear differential device 12 is controlled as follows, for example. A current value that flows through the solenoid 60 according to the steering force or the steering angle is set in advance as a map. As a result, the value of the current flowing through the left and right solenoids 60 is controlled based on the turning direction and the steering force or the steering angle, and the rear wheel driving torque on the outside of the turning is controlled to be larger than the rear wheel driving torque on the inside of the turning. .

  The rear differential device 12 is a driving force distribution device that can control the distribution of the driving force between the front and rear wheels and can arbitrarily control the distribution of the driving force between the left and right rear wheels.

  In the four-wheel drive vehicle having the above-described configuration, the control device of the present invention when the front wheels or the rear wheels are punctured will be described below. FIG. 4 is a principle block diagram showing the principle of the present invention.

  The first air pressure detecting means 68 detects the air pressure of the left front wheel 21 and corresponds to the air pressure sensor 5a of FIG. The second air pressure detecting means 70 detects the air pressure of the right front wheel 23 and corresponds to the air pressure sensor 5b.

  The third air pressure detecting means 72 detects the air pressure of the left rear wheel 25 and corresponds to the air pressure sensor 5c. The fourth air pressure detecting means 74 detects the air pressure of the right rear wheel 27 and corresponds to the air pressure sensor 5d.

  The air pressure comparing means 76 compares a predetermined wheel air pressure threshold value with the air pressure detected by the first to fourth air pressure detecting means 68 to 74. The air pressure abnormality detecting means 78 detects the front wheels 21, 23 or the rear wheels 25, 27 whose air pressure is below the threshold based on the output of the air pressure comparing means 76.

  The first air pressure ratio calculating means 80 calculates the air pressure ratio between the pair of front wheels 21 and 23 based on the outputs of the first and second air pressure detecting means 68 and 70. The second air pressure ratio calculating means 82 calculates the air pressure ratio between the pair of rear wheels 25 and 27 based on the outputs of the third and fourth air pressure detecting means 72 and 74.

  The driving state detection means 84 detects whether the vehicle is in a straight traveling state, a left turning state, or a right turning state based on the steering angle of the steering wheel.

  When the air pressure abnormality detecting means 78 detects an air pressure abnormality, that is, a puncture, the control means 86 calculates the vehicle operating state detected by the operating state detecting means 84 and the first and second air pressure ratio calculating means 80 and 82. In accordance with the air pressure ratio, the driving force distribution device, that is, the driving force distribution amount of the rear differential device 12 is changed.

  That is, when the abnormality in the air pressure detected by the air pressure abnormality detecting means 78 is one of the front wheels 21 and 23, the driving state of the vehicle detected by the driving state detecting means 84, that is, the vehicle is traveling straight or turning left The driving force distribution amount of the driving force distribution device is changed according to the driving state of whether the vehicle is turning right or the air pressure ratio of the front wheels 21 and 23 calculated by the first air pressure ratio calculating means 80.

  On the other hand, when the abnormality in the air pressure detected by the air pressure abnormality detecting means 78 is one of the rear wheels 25, 27, the vehicle operating state detected by the operating state detecting means 84 and the second air pressure ratio calculating means 82 are used for calculation. In accordance with the air pressure ratio between the rear wheels 25 and 27, the driving force distribution amount of the driving force distribution device is changed.

  Hereinafter, control of the driving force distribution amount of the driving force distribution device, that is, the rear differential device 12 under various conditions will be described.

  FIG. 5 schematically shows a case where the left front wheel 21 is punctured during a left turn (while turning left). In this case, since the punctured inner ring 21 is shrunken, the rear part of the vehicle is greatly rotated in the direction of the outer ring, and the running stability is lowered.

  Therefore, in this case, according to the change in the air pressure ratio between the left and right front wheels 21 and 23, the rear differential device 12 changes the torque distribution amount of the left and right rear wheels 25 and 27 to the distribution amount of the right rear wheel 27 as shown in FIG. Is controlled to be large.

  That is, as shown in FIG. 7, as the air pressure of the punctured left front wheel 21 decreases as shown by a curve 88, the rear differential device 12 is controlled to show the left and right rear wheels 25, 94 as shown by curves 92, 94. The torque distribution amount of 27 is gradually increased.

  At this time, the torque distribution amount of the right rear wheel 27 indicated by the curve 94 is controlled to be larger than the torque distribution amount of the left rear wheel 25 indicated by the curve 92. In FIG. 7, a straight line 90 indicates the air pressure of the right front wheel 23.

  As apparent from FIG. 7, as the air pressure of the punctured left front wheel tire 21 gradually decreases, the torque distribution amount of the left and right rear wheels 25 and 27 is controlled to gradually increase. Accordingly, the torque distribution amount of the left and right front wheels 21 and 23 is gradually reduced.

  FIG. 8 shows the relationship between the torque distribution amount coefficients J1 and J2 of the rear wheels 25 and 27 according to the change in the air pressure ratio between the left and right front wheels 21 and 23. A curve 96 indicates a change in the air pressure ratio between the left and right front wheels 21, 23, a curve 98 indicates a coefficient J1 of the torque distribution amount of the left rear wheel 25, and a curve 100 indicates a coefficient J2 of the torque distribution amount of the right rear wheel 27. Show.

  That is, when the left front wheel 21 is punctured, the torque distribution amount of the left and right rear wheels is controlled as follows.

Right rear wheel torque distribution amount = conventional right rear wheel torque distribution amount × J2 = conventional right rear wheel torque distribution amount × (2-left front wheel air pressure / right front wheel air pressure) × K
Left rear wheel torque distribution amount = conventional left rear wheel torque distribution amount × J1 = conventional left rear wheel torque distribution amount × 1/2 × (3-left front wheel air pressure / right front wheel air pressure) × K
here,
K = tire contact area × assumed μ × car inclination angle The contact area of the tire is obtained from a pneumatic-contact area map as shown in FIG. P1 is the air pressure when the tire is completely punctured, and P2 is the air pressure when the tire is normal. S1 is a contact area when the tire is normal, and S2 is a contact area when the tire is completely punctured.

  Assuming μ assumes the current road surface condition from an information source such as a car navigation system or radio, and obtains the assumed μ from an assumed μ map as shown in Table 1.

車傾き角度は、図１０に示すような空気圧−タイヤ半径マップから四輪タイヤの半径を求め、車傾き角度を計算する。図１０でＰ１は完全パンク時の空気圧、Ｐ２はタイヤ正常時の空気圧である。また、Ｒ１は完全パンク時のタイヤ半径、Ｒ２はタイヤ正常時のタイヤ半径である。

For the vehicle inclination angle, the radius of the four-wheel tire is obtained from an air pressure-tire radius map as shown in FIG. 10, and the vehicle inclination angle is calculated. In FIG. 10, P1 is the air pressure at the time of complete puncture, and P2 is the air pressure at the time of normal tire. Further, R1 is a tire radius when fully punctured, and R2 is a tire radius when the tire is normal.

  FIG. 11 shows a schematic diagram of the driving force distribution control when the left front wheel 21 is punctured during a right turn (during a right turn). In this case, the torque distribution amount distributed to the rear wheels 25 and 27 is controlled by the rear differential device 12 as follows.

Right rear wheel torque distribution amount = conventional right rear wheel torque distribution amount × 1/2 × (3-left front wheel air pressure / right front wheel air pressure) × K
Left rear wheel torque distribution amount = conventional left rear wheel torque distribution amount × (2-left front wheel air pressure / right front wheel air pressure) × K
FIG. 12 is a schematic diagram of the driving force distribution control when the left front wheel 21 is punctured while traveling straight ahead. In this case, the torque distributed to the left and right rear wheels 25 and 27 by the rear differential device 12 is controlled as follows.

Right rear wheel torque distribution amount = conventional right rear wheel torque distribution amount Left rear wheel torque distribution amount = conventional left rear wheel torque distribution amount × (2-left front wheel air pressure / right front wheel air pressure) × K
FIG. 13 is a schematic diagram of driving force distribution control when the left front wheel 21 is punctured during a reverse right turn. In this case, the torque distributed to the left and right rear wheels 25 and 27 by the rear differential device 12 is controlled as follows.

Right rear wheel torque distribution amount = conventional right rear wheel torque distribution amount × 1/2 × (3-left front wheel air pressure / right front wheel air pressure) × K
Left rear wheel torque distribution amount = conventional left rear wheel torque distribution amount × (2-left front wheel air pressure / right front wheel air pressure) × K
FIG. 14 is a schematic diagram of the driving force distribution control when the left front wheel 21 is punctured during a reverse left turn. In this case, the torque distributed to the left and right rear wheels 25 and 27 is controlled by the rear differential device 12 as follows.

Right rear wheel torque distribution amount = conventional right rear wheel torque distribution amount × (2-left front wheel air pressure / right front wheel air pressure) × K
Left rear wheel torque distribution amount = conventional left rear wheel torque distribution amount × 1/2 × (3-left front wheel air pressure / right front wheel air pressure) × K
FIG. 15 is a schematic diagram of the driving force distribution control when the left front wheel 21 is punctured during reverse straight traveling. In this case, the torque distributed to the left and right rear wheels 25 and 27 by the rear differential device 12 is controlled as follows.

Right rear wheel torque distribution amount = conventional right rear wheel torque distribution amount × (2-left front wheel air pressure / right front wheel air pressure) × K
Left rear wheel torque distribution amount = conventional left rear wheel torque distribution amount FIG. 16 is a schematic diagram of drive force distribution control when the left rear wheel 21 is punctured during a left turn. In this case, the torque distributed to the left and right rear wheels 25 and 27 by the rear differential device 12 is controlled as follows.

Right rear wheel torque distribution amount = conventional right rear wheel torque distribution amount × (2-left rear wheel air pressure / right rear wheel air pressure) × K
Left rear wheel torque distribution amount = conventional left rear wheel torque distribution amount × 1/2 × (3-left rear wheel air pressure / right rear wheel air pressure) × K
FIG. 17 is a schematic diagram of the driving force distribution control when the left rear wheel 25 is punctured during a right turn. In this case, the torque distributed to the left and right rear wheels 25 and 27 by the rear differential device 12 is controlled as follows.

Right rear wheel torque distribution amount = conventional right rear wheel torque distribution amount × 1/2 × (3-left rear wheel air pressure / right rear wheel air pressure) × K
Left rear wheel torque distribution amount = conventional left rear wheel torque distribution amount × (2-left rear wheel air pressure / right rear wheel air pressure) × K
FIG. 18 is a schematic diagram of the driving force distribution control when the left rear wheel 25 is punctured during straight traveling. In this case, the torque distributed to the left and right rear wheels 25 and 27 by the rear differential device 12 is controlled as follows.

Right rear wheel torque distribution amount = conventional right rear wheel torque distribution amount Left rear wheel torque distribution amount = conventional left rear wheel torque distribution amount × (2-left rear wheel air pressure / right rear wheel air pressure) × K
FIG. 19 shows a schematic diagram of the driving force distribution control when the left rear wheel 25 is punctured during a reverse right turn. In this case, the torque distributed to the left and right rear wheels 25 and 27 by the rear differential device 12 is controlled as follows.

Right rear wheel torque distribution amount = conventional right rear wheel torque distribution amount × 1/2 × (3-left rear wheel air pressure / right rear wheel air pressure) × K
Left rear wheel torque distribution amount = conventional left rear wheel torque distribution amount × (2-left rear wheel air pressure / right rear wheel air pressure) × K
FIG. 20 is a schematic diagram of the driving force distribution control when the left rear wheel 25 is punctured during a reverse left turn. In this case, the torque distributed to the left and right rear wheels 25 and 27 by the rear differential device 12 is controlled as follows.

Right rear wheel torque distribution amount = conventional right rear wheel torque distribution amount × (2-left rear wheel air pressure / right rear wheel air pressure) × K
Left rear wheel torque distribution amount = conventional left rear wheel torque distribution amount × 1/2 × (3-left rear wheel air pressure / right rear wheel air pressure) × K
FIG. 21 is a schematic diagram of the driving force distribution control when the left rear wheel 25 is punctured during reverse straight traveling. In this case, the torque distributed to the left and right rear wheels 25 and 27 by the rear differential device 12 is controlled as follows.

Right rear wheel torque distribution amount = conventional right rear wheel torque distribution amount × (2-left rear wheel air pressure / right rear wheel air pressure) × K
Left rear wheel torque distribution amount = conventional left rear wheel torque distribution amount In the embodiment described above, an example in which the drive control of the present invention during tire puncture is applied to an FF vehicle-based four-wheel drive vehicle has been described. However, the present invention is not limited to this, and can be similarly applied to a four-wheel drive vehicle based on a front engine / rear drive (FR) vehicle. In this case, the driving force distribution device is disposed on the front wheel side.

It is a schematic block diagram of the power transmission device of the FF vehicle base four-wheel drive vehicle which can apply this invention. It is sectional drawing of the speed increasing apparatus and the rear differential apparatus arrange | positioned in the downstream. It is explanatory drawing which shows the left turn state of a four-wheel drive vehicle. It is a principle block diagram which shows the principle of this invention. It is a schematic diagram when the left front wheel is punctured during a left turn. It is a schematic diagram of the driving force distribution control when the left front wheel is punctured during a left turn. It is explanatory drawing which shows the torque distribution amount to the left-right rear wheel according to the air pressure change of the punctured left front wheel tire. It is a figure explaining the change of the coefficient of the torque distribution amount of the right and left rear wheel according to the change of the air pressure ratio of the left and right front wheels. It is a pneumatic-contact area map. It is a pneumatic-tire radius map. It is a schematic diagram of the driving force distribution control when the left front wheel is punctured during a right turn. It is a schematic diagram of the driving force distribution control when the left front wheel is punctured while traveling straight ahead. It is a schematic diagram of the driving force distribution control when the left front wheel is punctured during reverse left turn. It is a schematic diagram of the driving force distribution control when the left front wheel is punctured during a reverse right turn. It is a schematic diagram of driving force distribution control when the left front wheel is punctured during reverse straight traveling. It is a schematic diagram of driving force distribution control when the left rear wheel is punctured during a left turn. It is a schematic diagram of the driving force distribution control when the left rear wheel is punctured during a right turn. It is a schematic diagram of driving force distribution control when the left rear wheel is punctured during straight traveling. It is a schematic diagram of driving force distribution control when the left rear wheel is punctured during reverse left turn. It is a schematic diagram of driving force distribution control when the left rear wheel is punctured during reverse right turn. It is a schematic diagram of the driving force distribution control when the left rear wheel is punctured during reverse straight traveling.

Explanation of symbols

5a to 5d Pneumatic sensor 9 Steering angle sensor 10 Speed increasing device 12 Rear differential device 21 Left front wheel 23 Right front wheel 25 Left rear wheel 27 Right rear wheel 88 Left front wheel tire air pressure 92 Left rear wheel torque distribution 94 Right rear wheel Torque distribution amount 96 Air pressure ratio of left and right front wheels 98 Coefficient of torque distribution amount of left rear wheel 100 Coefficient of torque distribution amount of right rear wheel

Claims (8)

A pair of main drive wheels always connected to the drive source, and a pair of slave drive wheels driven by the drive source via a drive force distribution device, the main drive wheel and the slave drive by the drive force distribution device A control device for a four-wheel drive vehicle capable of distributing driving force between wheels and between left and right driven wheels,
Driving state detection means for detecting the driving state of the vehicle;
First and second air pressure detecting means for detecting air pressure of the pair of main drive wheels;
An air pressure comparison means for comparing a predetermined wheel air pressure threshold value with the air pressure detected by the first and second air pressure detection means;
An air pressure abnormality detecting means for detecting a main drive wheel having an air pressure equal to or lower than the threshold based on an output of the air pressure comparing means;
An air pressure ratio calculating means for calculating a ratio of air pressures of the pair of main drive wheels based on outputs of the first and second air pressure detecting means;
When an abnormality in air pressure is detected by the air pressure abnormality detecting means, the driving force of the driving force distribution device is determined according to the vehicle operating state detected by the operating state detecting means and the air pressure ratio calculated by the air pressure ratio calculating means. Control means for changing the distribution amount;
A control device for a four-wheel drive vehicle.   The control means detects an abnormality in air pressure when the driving state of the vehicle detected by the driving state detection means is turning to the main drive wheel side where the air pressure abnormality is detected by the air pressure abnormality detection means. The driving force distribution amount of the slave driving wheel opposite to the main driving wheel is controlled to be larger than the driving force distribution amount distributed to the slave driving wheel on the same side as the main driving wheel in which an abnormality in air pressure is detected. The control device for a four-wheel drive vehicle according to claim 1.   The control means detects the air pressure abnormality when the driving state of the vehicle detected by the driving state detection means is turning to the opposite side of the main drive wheel where the air pressure abnormality is detected by the air pressure abnormality detecting means. The driving force distribution amount of the slave driving wheel on the same side as the main driving wheel in which the abnormality of the air pressure is detected by the means is the driving force of the slave driving wheel on the opposite side of the main driving wheel in which the abnormality is detected by the air pressure abnormality detecting means. 2. The control device for a four-wheel drive vehicle according to claim 1, wherein the control is performed so as to be larger than the distribution amount.   When the driving state of the vehicle detected by the driving state detecting unit is a straight running state, the control unit is a driven wheel on the same side as the main driving wheel side where the abnormality in the air pressure is detected by the air pressure abnormality detecting unit. 2. The control device for a four-wheel drive vehicle according to claim 1, wherein the drive force distribution amount is controlled to be larger than the drive force distribution amount of the opposite driven wheel on the opposite side. A pair of main drive wheels always connected to the drive source, and a pair of slave drive wheels driven by the drive source via a drive force distribution device, the main drive wheel and the slave drive by the drive force distribution device A control device for a four-wheel drive vehicle capable of distributing driving force between wheels and between left and right driven wheels,
Driving state detection means for detecting the driving state of the vehicle;
First and second air pressure detecting means for detecting air pressure of the pair of driven wheels;
An air pressure comparison means for comparing a predetermined wheel air pressure threshold value with the air pressure detected by the first and second air pressure detection means;
An air pressure abnormality detecting means for detecting a driven wheel whose air pressure is equal to or lower than the threshold based on an output of the air pressure comparing means;
An air pressure ratio calculating means for calculating a ratio of air pressures of the pair of driven wheels based on outputs of the first and second air pressure detecting means;
When an abnormality in air pressure is detected by the air pressure abnormality detecting means, the driving force of the driving force distribution device is determined according to the vehicle operating state detected by the operating state detecting means and the air pressure ratio calculated by the air pressure ratio calculating means. Control means for changing the distribution amount;
A control device for a four-wheel drive vehicle.   When the vehicle driving state detected by the driving state detecting unit is turning to the driven wheel where the air pressure abnormality is detected by the air pressure abnormality detecting unit, the control unit detects the air pressure by the air pressure abnormality detecting unit. The drive force distribution amount of the slave drive wheel on the opposite side to the slave drive wheel in which the abnormality is detected is controlled to be larger than the drive force distribution amount of the slave drive wheel in which the abnormality in air pressure is detected The control device for a four-wheel drive vehicle according to claim 5.   When the driving state of the vehicle detected by the driving state detecting unit is turning to the opposite side of the driven wheel that has detected the abnormal air pressure by the air pressure abnormality detecting unit, the control unit uses the air pressure abnormality unit. 6. The four-wheel drive vehicle according to claim 5, wherein the drive force distribution amount of the slave drive wheel that detects an abnormality in air pressure is controlled to be larger than the drive force distribution amount of the slave drive wheel on the opposite side. Control device.   When the driving state of the vehicle detected by the driving state detection unit is a straight traveling state, the control unit determines the driving force distribution amount of the driven wheel in which an abnormality in air pressure is detected by the air pressure abnormality detection unit, 6. The control device for a four-wheel drive vehicle according to claim 5, wherein the control is performed so as to be larger than a driving force distribution amount of the opposite driven wheel on the opposite side.

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