JP2021172247A - Control device of four-wheel drive vehicle - Google Patents

Abstract

To improve a turning performance of a vehicle.SOLUTION: A control device of a vehicle 1 having two motors 3L, 3R driving one of front and rear wheels and a drive source 3F driving the other of front and rear wheels comprises: a first calculation unit 12 which calculates front and rear request torque Tf, Tr; a second calculation unit 15 which calculates right and left request torque TrL, TrR on the basis of a request torque difference ΔTd requested between the right and left wheels and one request torque Tr; a limit determination unit 16 which determines whether the request torque difference ΔTd can be achieved by executing limit determination including determination on whether the request torque TrL, TrR exceeds upper limit values TrLLim, TrRLim; and a third calculation unit 18 which recalculates the request torque TrL, TrR in the case of understeer when the request torque difference ΔTd cannot be achieved and calculates a torque difference insufficiency ΔTi that is insufficient for achieving the request torque difference ΔTd as a brake amount B. The motors 3L, 3R and a brake pressure are controlled on the basis of the calculated request torque TrL', TrR' and the brake amount B.SELECTED DRAWING: Figure 2

Description

The present invention includes two motors that drive one of the front and rear wheels, and a drive source that is provided independently of these motors and drives the other of the front and rear wheels, and is driven by the two motors. The present invention relates to a control device for a four-wheel drive vehicle capable of applying a torque difference to the left and right wheels.

Conventionally, in a four-wheel drive vehicle, a technique has been proposed in which the behavior of the vehicle is stabilized by controlling the torque (driving force) of a plurality of drive sources. For example, in Patent Document 1, the driving force command values of each driving source are adjusted by calculating each driving force in the front-rear direction and the turning direction and the front-rear distribution ratio, which are required according to the operation by the occupant and the state of the vehicle. .. Further, in Patent Document 2, the yaw moment generated after a lapse of a predetermined time is predicted based on the actual yaw rate, and the yaw moment opposite to the yaw moment for generating the yaw rate is added after the lapse of a predetermined time, so that the road surface condition is abrupt. We are trying to stabilize the behavior of the vehicle in situations where it changes to.

JP-A-2009-177994 Japanese Unexamined Patent Publication No. 2005-247276

By the way, since the torque that can be output by each drive source (for example, a motor) is determined by the running state of the vehicle, the state of the drive source, and the like, it is not always possible to output the required torque. Therefore, in a situation where a desired torque difference cannot be output when the vehicle turns, there is room for improvement as to how to control each drive source to improve the turning performance. In particular, when the vehicle is understeer or oversteer, the preferable vehicle behavior is different from each other. Therefore, it is desirable to determine the turning state of the vehicle and perform control according to the turning state.

The four-wheel drive vehicle control device of the present case was devised in view of such a problem, and one of the purposes is to improve the turning performance of the vehicle. Not limited to this purpose, it is also an action and effect derived by each configuration shown in the embodiment for carrying out the invention described later, and it is also for another purpose of this case to exert an action and effect that cannot be obtained by the conventional technique. be.

(1) The four-wheel drive vehicle control device disclosed here includes two motors that drive one of the front and rear wheels and a drive source that is provided independently of the two motors and drives the other of the front and rear wheels. A four-wheel drive vehicle control device capable of applying a torque difference to one of the left and right wheels driven by the two motors, the first calculation unit, the second calculation unit, and the limit determination. It is equipped with a unit, a turning determination unit, a third calculation unit, a motor control unit, and a brake control unit. The first calculation unit calculates the required torque required for each of the front and rear wheels. The second calculation unit is required for each of the left and right wheels based on the required torque difference required between the left and right wheels and the one required torque of the front and rear wheels calculated by the first calculation unit. Calculate the required torque of. The limit determination unit realizes the required torque difference by performing limit determination including determination of whether or not each of the left and right required torques calculated by the second calculation unit exceeds a predetermined torque upper limit value. Determine if it is possible. The turning determination unit determines whether or not the vehicle is understeer when the limit determination unit determines that the required torque difference cannot be realized. When the turning determination unit determines that the vehicle is understeer, the third calculation unit recalculates the left and right required torques and realizes the required torque difference between the left and right wheels. The insufficient torque difference is calculated as the brake amount of the vehicle. The motor control unit controls the two motors based on the left and right required torques calculated by the third calculation unit. The brake control unit controls the brake pressure based on the brake amount calculated by the third calculation unit.

(2) It is preferable that the limit determination includes a determination as to whether or not the required torque difference exceeds a predetermined torque difference upper limit value.
(3) When the left and right required torques are recalculated, the third calculation unit obtains the sum of the left and right required torques as the one required torque of the front and rear wheels calculated by the first calculation unit. It is preferable to calculate as follows.
(4) It is preferable that the turning determination unit determines whether or not there is understeer at the time of turnout of the vehicle.

(5) When the drive source control unit that controls the drive source and the turning determination unit determine that the vehicle is not understeer, the control device recalculates the left and right required torques and the torque. It is preferable to further include a fourth calculation unit that adds the difference shortage to the other required torque of the front and rear wheels. In this case, the motor control unit controls the two motors based on the left and right required torques calculated by the fourth calculation unit when the calculation is recalculated by the fourth calculation unit. When the drive source control unit is recalculated by the fourth calculation unit, it is preferable that the drive source control unit controls the drive source based on the other required torque calculated by the fourth calculation unit.

(6) The turning determination unit determines whether or not the required torque difference is understeer when the vehicle is turning in or cornering when the limit determination unit determines that the required torque difference cannot be realized. The fourth calculation unit adds the insufficient torque difference to the other required torque of the front and rear wheels even when the determination is skipped by the turning determination unit, and the left and right required torques. It is preferable to recalculate.
(7) It is preferable that the two motors drive the rear wheels and the drive source drives the front wheels.

According to the disclosed four-wheel drive vehicle control device, it is possible to improve the turning performance of the vehicle while suppressing the tendency of understeer.

It is a schematic diagram which shows the whole structure of the four-wheel drive vehicle provided with the control device which concerns on one Embodiment. It is a block diagram of the control device of FIG. It is a flowchart which illustrates the control procedure which is carried out by the EV-ECU of the control device which concerns on one Embodiment. It is a schematic diagram for demonstrating the operation in the control device which concerns on one Embodiment, (a) is the state of FIG. 4 (a) when the right required torque exceeds the upper limit when turning left. In the case of cornering, FIG. 4C shows a case where it is determined that the vehicle is turned out and oversteered in the state of FIG. 4A.

A four-wheel drive vehicle control device as an embodiment will be described with reference to the drawings. The embodiments shown below are merely examples, and there is no intention of excluding the application of various modifications and techniques not specified in the following embodiments. Each configuration of the present embodiment can be variously modified and implemented without departing from the gist thereof. In addition, it can be selected as needed, or can be combined as appropriate.

[1. overall structure]
The control device of this embodiment is mounted on the vehicle 1 shown in FIG. The vehicle 1 includes two motors 3L and 3R that drive one of the front and rear wheels 9f and 9r, and a drive source 3F that is provided independently of the two motors 3L and 3R and drives the other of the front and rear wheels 9f and 9r. It is a four-wheel drive electric vehicle equipped with. In the vehicle 1 of the present embodiment, the two motors 3L and 3R drive the rear wheels 9r, and the other drive source 3F drives the front wheels 9f. The front-rear arrangement of the drive source 3F and the motors 3L and 3R may be reversed.

The vehicle 1 is provided with a mechanism capable of applying a torque difference to the left and right rear wheels 9r (one of the left and right wheels, hereinafter also referred to as "left and right wheels 9rL, 9rR") driven by two motors 3L and 3R. The vehicle 1 of the present embodiment is provided with a differential device 6 (power distribution mechanism) for a vehicle having an AYC (active yaw control) function, and is interposed between the left and right wheels 9r. The AYC function is a function that adjusts the magnitude of the yaw moment by independently controlling the sharing ratio of the driving force (driving torque) in the left and right drive wheels, thereby stabilizing the posture of the vehicle in the yaw direction. The vehicle 1 of the present embodiment passively transmits not only the AYC function but also the function of transmitting the driving torque to the left and right wheels 9r to drive the vehicle 1 and the difference in the number of rotations of the left and right wheels 9rL and 9rR generated when the vehicle turns. It also has a function of absorbing.

The two motors 3L and 3R are AC motors driven by the electric power of the drive battery 2, and preferably have substantially the same output characteristics. Hereinafter, when these motors 3L and 3R are particularly distinguished, the motor 3L arranged on the left side of the vehicle 1 is referred to as "first motor 3L", and the motor 3R arranged on the right side of the vehicle 1 is referred to as "second motor 3L". It is called "motor 3R". The rotation speeds of the first motor 3L and the second motor 3R are decelerated by, for example, a reduction gear train built in the differential device 6 and transmitted to the left and right wheels 9rL and 9rR. The differential device 6 may be provided with a function of amplifying the torque difference between the two motors 3L and 3R.

The drive source 3F of the present embodiment is an AC motor driven by the electric power of the drive battery 2 like the motors 3L and 3R. The rotational speed of the drive source 3F is decelerated in the transaxle 5 and transmitted to the left and right front wheels 9f. Hereinafter, the drive source 3F is also referred to as a “motor 3F”. Inverters 4F, 4L, 4R are interposed between the drive battery 2 and the motors 3F, 3L, 3R, and electric power is converted by the inverters 4F, 4L, 4R. In FIG. 1, for convenience, the thick straight line indicating the power line between the inverter 4F and the drive battery 2 is omitted.

The vehicle 1 is provided with at least a wheel speed sensor 7 that detects the wheel speeds of the front and rear wheels 9f and 9r, and a motor rotation speed sensor 8 (for example, a resolver) that detects the rotation speeds of the motors 3F, 3L, and 3R. Be done. Further, the vehicle 1 may be provided with known sensors such as an accelerator opening sensor, a steering angle sensor, a motor temperature sensor, a battery temperature sensor, a battery voltage sensor, and a battery current sensor (all of which are not shown). The values detected by these sensors are transmitted to the vehicle control device 10 (EV-Electronic Control Unit, hereinafter referred to as "EV-ECU 10"). The EV-ECU 10 is a higher-level electronic control device that comprehensively controls the vehicle 1, and is configured as, for example, an LSI device or an embedded electronic device in which a microprocessor, ROM, RAM, or the like is integrated.

The vehicle 1 of the present embodiment includes FMCU20 (Front Motor Control Unit) and RMCU30L, 30R (Rear Motor Control Unit; motor control) as lower-level electronic control devices that operate based on commands from the EV-ECU 10. Part) is provided. The FMCU20 and RMCU30L, 30R are electrically connected to the inverters 4F, 4L, 4R, respectively, and control the motors 3F, 3L, 3R via the inverters 4F, 4F, 4R, respectively.

The vehicle 1 is provided with a braking unit 40 capable of independently braking at least one of the left and right wheels of the front and rear wheels 9f and 9r. As shown in FIG. 2, the braking unit 40 of the present embodiment is controlled by an ASCU 41 (Active Stability Control Unit) as a lower electronic control device that operates based on a command from the EV-ECU 10 and an ASCU 41. It has an H / U 42 (Hydraulic Unit). The ASCU 41 controls the H / U 42 in response to a command from the EV-ECU 10, and individually controls the mechanical braking devices (not shown) of the front and rear wheels 9f and 9r.

[2. Control configuration]
FIG. 2 is a block diagram showing an example of the control device of the present embodiment, and is mounted on the vehicle 1. In the present embodiment, the functions of the control device of the present invention are assigned to the plurality of electronic control devices 10, 20, 30L, 30R, 40 described above, but one electronic control device is provided with all the functions. You may be. As shown in FIG. 2, the EV-ECU 10 is provided with seven calculation units 11 to 15, 18 and 19 and three determination units 16, 17A and 17B. Hereinafter, they will be described in order.

The total drive torque calculation unit 11 calculates the total drive torque T required for the vehicle 1 based on, for example, the accelerator opening degree and the vehicle speed. The front-rear torque calculation unit 12 (first calculation unit) calculates the torques Tf and Tr required for the front and rear wheels 9f and 9r, respectively. That is, the front-rear torque calculation unit 12 uses the total drive torque T calculated by the total drive torque calculation unit 11 as the torque Tf (required torque, hereinafter "Fr torque Tf") required for the front wheels 9f based on the front-rear distribution ratio. (Indicated as) and the torque Tr (required torque, hereinafter referred to as “Rr torque Tr”) required for the rear wheels 9r. The front-rear distribution ratio may be a preset fixed value, or may be calculated by the front-rear torque calculation unit 12 based on the traveling state of the vehicle 1, the states of the motors 3F, 3L, 3R, and the like.

The required torque difference calculation unit 13 calculates the required torque difference ΔTd required between the left and right wheels 9rL and 9rR in order for the vehicle 1 to turn smoothly, for example, based on the vehicle speed, steering angle, and the like. The upper limit calculation unit 14 calculates three upper limit values TrL _Lim , TrR _Lim , and ΔT _Lim used in the limit determination described later. The upper limit values TrL _Lim and TrR _Lim are upper limits that can be output by the two motors 3L and 3R. For example, the operating state of each motor 3L and 3R is calculated based on the motor temperature. Since these upper limit values TrL _Lim and TrR _Lim are calculated respectively, they are not necessarily the same. The upper limit value ΔT _Lim is the upper limit of the torque difference that can be output between the two motors 3L and 3R, and is calculated based on _{, for example, the two upper limit values TrL Lim} and TrR _Lim. Hereinafter, when the three upper limit values TrL _Lim , TrR _Lim , and ΔT _Lim are distinguished from each other, they are referred to as left torque upper limit TrL _Lim , right torque upper limit TrR _Lim , and torque difference upper limit ΔT _Lim , respectively.

The left and right torque calculation unit 15 (second calculation unit) is based on the Rr torque Tr calculated by the front-rear torque calculation unit 12 and the required torque difference ΔTd calculated by the required torque difference calculation unit 13, and the left and right wheels 9rL and 9rR. The left and right required torques required for each of the above, that is, the left required torque TrL and the right required torque TrR are calculated. That is, the left-right torque calculation unit 15 distributes the Rr torque Tr to the left and right wheels 9rL and 9rR based on the required torque difference ΔTd.

The limit determination unit 16 performs a predetermined limit determination and determines whether or not the required torque difference ΔTd calculated by the required torque difference calculation unit 13 can be realized. The limit determination referred to here is whether or not the left and right required torques TrL and TrR described above _{exceed the respective torque upper limit values TrL Lim} and TrR _Lim , that is, the torque required for each motor 3L and 3R is the upper limit thereof. It is a judgment as to whether or not the value exceeds. The limit determination includes at least the following conditions 1 and 2. Further, it is preferable that the limit determination includes determination of whether or not the required torque difference ΔTd exceeds the torque difference upper limit value ΔT _Lim (condition 3 below).

== Limit judgment ==
Condition 1: Left required torque TrL> Left torque upper limit TrL _Lim
Condition 2: Right required torque TrR> Right torque upper limit TrR _Lim
Condition 3: Required torque difference ΔTd> Torque difference upper limit ΔT _Lim

When the limit determination unit 16 determines that the required torque difference ΔTd can be realized, the RMCU 30L and 30R control the motors 3L and 3R so as to output the left required torque TrL and the right required torque TrR, respectively. The FMCU 20 controls the drive source 3F so as to output the Fr torque Tf. As a result, the desired required torque difference ΔTd is realized, so that high turning performance is ensured.

On the other hand, when the limit determination unit 16 determines that the required torque difference ΔTd cannot be realized, a process described later is performed. In the present embodiment, first, the turning state determination unit 17A (turning determination unit) determines the turning state of the vehicle 1. Specifically, it is determined whether the vehicle 1 has begun to turn (at the time of turn-in), is in the middle of turning (at the time of cornering), or is in a state of exiting the turn (at the time of turn-out). This determination is performed based on, for example, vehicle speed, steering angle, lateral G, camera information, and the like. When the turning state determination unit 17A determines that the vehicle is at the time of turnout, the US determination unit 17B (turning determination unit) further determines whether or not the vehicle 1 is understeer (US). In other words, the US determination unit 17B skips the determination of whether or not it is understeer when the vehicle 1 is turning in or cornering.

When the US determination unit 17B determines that the vehicle 1 is understeer, the brake amount calculation unit 18 (third calculation unit) recalculates the left and right required torques TrL and TrR, and between the left and right wheels 9rL and 9rR. The torque difference deficiency ΔTi, which is insufficient to realize the required torque difference ΔTd, is calculated as the brake amount B of the vehicle 1. That is, the torque difference that cannot be realized only by the motors 3L and 3R is supplemented as the brake amount (the brake is used together). Further, when the brake amount calculation unit 18 recalculates the left and right required torques TrL and TrR, the sum of the left and right required torques TrL'and TrR'is the Rr torque Tr (front and rear) calculated by the front and rear torque calculation unit 12. Calculate so that the required torque is one of the wheels 9f and 9r). As a result, the Rr torque Tr calculated by the front-rear torque calculation unit 12 is secured even when the brake is used together.

When the US determination unit 17B determines that the vehicle 1 is not understeer, the torque movement calculation unit 19 (fourth calculation unit) recalculates the left and right required torques TrL and TrR, and between the left and right wheels 9rL and 9rR. The torque difference shortage ΔTi, which is insufficient to realize the required torque difference ΔTd, is added to the Fr torque Tf (the other required torque of the front and rear wheels 9f and 9r). That is, a torque difference that cannot be realized only by the motors 3L and 3R is realized by using another drive source 3F. Further, when the torque movement calculation unit 19 recalculates the left and right required torques TrL and TrR, the torque movement calculation unit 19 calculates so that the difference between the left and right required torques TrL'and TrR'is the required torque difference ΔTd. As a result, the required torque difference ΔTd is secured even when a part of the required torque is moved to the front side.

The torque movement calculation unit 19 of the present embodiment is left and right even when the determination by the US determination unit 17B is skipped (that is, when the turning state determination unit 17A determines that it is at turn-in or cornering). The required torques TrL and TrR are recalculated, and the torque difference shortage ΔTi is added to the Fr torque Tf. That is, in the EV-ECU 10 of the present embodiment, when the limit determination unit 16 determines that the required torque difference ΔTd cannot be realized, the brake is used together only when understeer is performed at the time of turnout, and other cases are used in other cases. The torque is transferred to the drive source 3F.

When the Fr torque Tf is recalculated by the torque movement calculation unit 19, the FMCU 20 controls the drive source 3F based on the calculated Fr torque Tf'. For both the left RMCU30L and the right RMCU30R, when the left and right required torques TrL and TrR are recalculated by the brake amount calculation unit 18 or the torque movement calculation unit 19, the calculated left and right required torques TrL'and TrR' The motors 3L and 3R are controlled based on the above. When the brake amount B is calculated by the brake amount calculation unit 18, the ASCU 41 controls the brake pressure of the H / U 42 based on the brake amount B.

[3. flowchart]
FIG. 3 is an example of the control performed by the EV-ECU 10 described above. This flowchart is repeatedly executed, for example, at a predetermined calculation cycle. First, in step S1, detection values (various information) from various sensors provided in the vehicle 1 are acquired.

Steps S2 to S6 are calculation steps. In step S2, the total drive torque calculation unit 11 calculates the total drive torque T, and in the subsequent step S3, the front-rear torque calculation unit 12 calculates the Fr torque Tf and the Rr torque Tr. In step S4, the required torque difference calculation unit 13 calculates the required torque difference ΔTd, and in the following step S5, the upper limit calculation unit 14 calculates three upper limit values TrL _Lim , TrR _Lim , and ΔT _Lim . Then, in step S6, the left required torque TrL and the right required torque TrR are calculated.

Steps S7 to S9 are determination steps. In step S7, it is determined whether or not the required torque difference ΔTd can be realized. In this determination, the required torque difference ΔTd calculated in step S4 and each upper limit value calculated in step S5 are used. If the required torque difference ΔTd can be realized, the process proceeds to step S14, and the Fr torque Tf calculated in step S3 and the required torques TrL and TrR calculated in step S6 are output to FMCU20 and RMCU30L and 30R (step S14). , Return this flow.

On the other hand, if it is determined in step S7 that the required torque difference ΔTd cannot be realized, the turning state determination unit 17A determines whether or not the turnout is achieved (step S8). If it is a turnout, the US determination unit 17B further determines whether or not there is understeer (step S9). When it is turnout and understeer, the process proceeds to step S10, and the left and right required torques TrL'and TrR' are recalculated by the brake amount calculation unit 18, and the torque difference shortage ΔTi is calculated as the brake amount B (step). S11).

If it is not turnout, or if it is turnout but not understeer, the process proceeds to step S12, and the torque difference calculation unit 19 recalculates the left and right required torques TrL'and TrR', and the torque difference shortage ΔTi is calculated. It is added to the Fr torque Tf and the Fr torque Tf'is also recalculated (step S13). Then, the values calculated in each of steps S10 to S13 are output to each of FMCU20, RMCU30L, 30R, and ASCU41 (step S14), and this flow is returned.

[4. Action, effect]
Here, an example of the control content by the above-mentioned control device will be described with reference to FIGS. 4 (a) to 4 (c). For example, as shown in FIG. 4A, when only the above condition 2 is satisfied when the vehicle 1 makes a left turn (TrR> TrR _Lim ), the required torque difference ΔTd cannot be output because the right required torque TrR cannot be output. It cannot be realized. In this case, the turning state is first determined.

For example, at the time of cornering, as shown in FIG. 4B, the right required torque TrR is recalculated so as to be clipped to the _{right torque upper limit TrR Lim (TrR'= TrR Lim} ). Further, in order to maintain the required torque difference ΔTd, the left required torque TrL ′ is recalculated (TrL ′ = TrR ′ − ΔTd), and the torque difference ΔTi [= Tr− (TrR ′ + TrL ′)] is insufficient accordingly. Is added to Fr torque Tf, and Fr torque Tf ′ is also recalculated (Tf ′ = Tf + ΔTi).

Further, for example, in the case of understeer at the time of turnout, as shown in FIG. 4C, the right required torque TrR is recalculated so as to be clipped to the _{right torque upper limit TrR Lim (TrR'= TrR Lim} ). Further, in order to maintain the Rr torque Tr, the left required torque TrL'is recalculated (TrL'= Tr-TrR'), and the torque difference ΔTi [= ΔTd- (TrR'-TrL')] that is insufficient accordingly. Is calculated as the brake amount B (B = ΔTi).

(1) Therefore, in the above-mentioned control device, if understeer occurs when the required torque difference ΔTd cannot be realized only by the two motors 3L and 3R, the torque difference shortage ΔTi is calculated as the brake amount B. Since the required torque difference ΔTd is realized by using the brake control together, an appropriate torque difference can be applied to the left and right wheels 9rL and 9rR. As a result, the turning performance of the vehicle 1 can be improved while suppressing the tendency of understeer.

(2) In the above-mentioned control device, if the limit determination includes the condition 3, the determination accuracy of whether or not the required torque difference ΔTd can be realized can be improved only by the two motors 3L and 3R. Therefore, the tendency of understeer can be suppressed more appropriately and the turning performance of the vehicle 1 can be improved.

(3) Further, in the above-mentioned control device, when the brake amount calculation unit 18 recalculates the left and right required torques TrL and TrR, the sum of the left and right required torques TrL'and TrR'is calculated by the front-rear torque calculation unit 12. It is calculated so that the required torque of one of the front and rear wheels (for example, Rr torque Tr) is obtained. As a result, even when the required torque difference ΔTd is realized by using the brake control together, the required torque (here, Rr torque Tr) is maintained, so that it is difficult to give the driver a feeling of deceleration and the drive feeling is improved. Can be planned.

(4) In the control device described above, the turning state determination unit 17A and the US determination unit 17B determine whether or not there is understeer at the time of turnout. The turning state of the vehicle 1 is difficult to stabilize at the timing of exiting the turning depending on the running state such as acceleration / deceleration. On the other hand, according to the above-mentioned control device, when the vehicle 1 comes out of the turn and understeer, the required torque difference ΔTd can be appropriately realized without changing the front-rear distribution ratio by using it together with the brake control. It is possible to stabilize the behavior of the vehicle 1 at the time of out and improve the turning performance.

(5) In the above-mentioned control device, when it is determined that there is no understeer, the torque movement calculation unit 19 adds the torque difference shortage ΔTi to the other drive source 3F and recalculates the left and right required torques TrL and TrR. , FMCU20 and RMCU30L, 30R control the drive source 3F and the motors 3L, 3R. As a result, when it is determined that the required torque difference ΔTd cannot be realized, for example, in the case of oversteer, the distribution ratio of the front-rear torque is changed (a part of one required torque Tr is added to the other). The spin tendency can be suppressed. Therefore, the tendency of oversteer can be suppressed and the turning performance can be improved.

(6) Further, in the above-mentioned control device, when the required torque difference ΔTd cannot be realized, the determination by the US determination unit 17B is skipped at the time of turn-in or cornering, and the calculation by the torque movement calculation unit 19 is performed. Will be implemented. At turn-in or cornering, the behavior of vehicle 1 does not become unstable even if the front-rear distribution ratio is changed compared to at turn-out, so even if there is a tendency to oversteer, the front-rear distribution ratio is changed. By realizing the required torque difference ΔTd, the tendency of oversteer can be suppressed. Therefore, by omitting the determination process, it is possible to improve the turning performance of the vehicle 1 while reducing the calculation load.

(7) In the vehicle 1 described above, the rear wheels 9r are driven by two motors 3L and 3R, and the front wheels 9f are driven by another drive source 3F. That is, it is possible to apply a torque difference to the left and right rear wheels 9rL and 9rR. In such a four-wheel drive vehicle 1, if the front-rear distribution ratio of the required torque is changed to increase the driving force of the drive source 3F on the front wheel 9f side during understeer, the vehicle 1 becomes easier to approach and the occupant It can give a sense of discomfort. On the other hand, in the above-mentioned control device, the front-rear distribution ratio is not changed at the time of understeer, and the amount that cannot generate the torque difference is supplemented as the brake amount, thereby suppressing the understeer tendency and stabilizing the behavior of the vehicle 1. The turning performance can be improved. The wheel for applying the brake may be one of the front wheels 9f and the rear wheel 9r, or may be a plurality of wheels.

[5. Modification example]
Each configuration of the vehicle 1 and the control device described above is an example, and is not limited to the above-described one. For example, the condition 3 may not be included in the above limit determination. Further, when the limit determination unit 16 determines that the required torque difference ΔTd cannot be realized, the control may be performed to supplement the torque difference shortage ΔTi by the brake only when the vehicle 1 is oversteered. That is, the torque movement calculation unit 19 for changing the front-rear distribution ratio of the required torque is omitted, and the front-rear torque calculation unit 12 and the left-right torque calculation unit 15 calculate the oversteer at the time of turn-in, cornering, or turn-out. The value may be output as it is.

Further, in the above embodiment, the complementary control by the brake is performed when understeer is performed at the time of turnout, but the complementary control by the brake may be performed even when the understeer is performed at the time of turn-in or cornering. As a result, when the vehicle 1 turns, the required torque difference ΔTd can be appropriately realized regardless of the turning timing, and the turning performance can be improved. The brake amount calculation unit 18 calculates so that the sum of the left and right required torques TrL'and TrR'is the Rr torque Tr when the left and right required torques TrL and TrR are recalculated. The recalculation method of the required torques TrL'and TrR' is not limited to this. Depending on the state of the motors 3L and 3R, a part of the required torque TrL and TrR may be moved to another drive source 3F to recalculate the required torque TrL'and TrR', or the realization of the Rr torque Tr may be abandoned. You may.

In the vehicle 1, the front wheels 9f are driven by the drive source 3F, and the rear wheels 9r are driven by the two motors 3L and 3R, but the drive target may be the opposite. Further, the drive source 3F is not limited to the motor, and may be an internal combustion engine. Further, the mechanism capable of applying torque difference to the left and right wheels is not limited to the above differential device 6, and may be configured such that torque can be individually applied to the right wheel and the left wheel, for example, an in-wheel motor.

1 Vehicle 3F Drive source, Motor 3L Motor, 1st motor 3R motor, 2nd motor 9f Front wheels 9r Rear wheels 9rL, 9rR Left and right wheels 10 Vehicle control device, EV-ECU
11 Total drive torque calculation unit 12 Front and rear torque calculation unit (first calculation unit)
13 Required torque difference calculation unit 14 Upper limit calculation unit 15 Left and right torque calculation unit (second calculation unit)
16 Limit Judgment Unit 17A Swivel State Judgment Unit (Swivel Judgment Unit)
17B US judgment unit (turning judgment unit)
18 Brake amount calculation unit (third calculation unit)
19 Torque movement calculation unit (fourth calculation unit)
20 FMCU (Drive source control unit)
30L, 30R RMCU (motor control unit)
40 Brake unit 41 ASCU (brake control unit)
42 H / U (Flood control unit)
B Brake amount
T total drive torque
Tf, Tf'Fr torque (required torque)
Tr Rr torque (required torque)
TrL, TrL ′ Left required torque
TrR, TrR'Right required torque
TrL _Lim left torque upper limit
TrR _Lim Right torque upper limit ΔTd Required torque difference ΔTi Torque difference shortage ΔT _Lim Torque difference upper limit

Claims (7)

It includes two motors that drive one of the front and rear wheels, and a drive source that is provided independently of the two motors and drives the other of the front and rear wheels, and the one that is driven by the two motors. It is a four-wheel drive vehicle control device that can apply torque difference to the left and right wheels.
The first calculation unit that calculates the required torque required for each of the front and rear wheels,
The left and right required torques required for each of the left and right wheels are calculated based on the required torque difference required between the left and right wheels and the required torque of one of the front and rear wheels calculated by the first calculation unit. Two calculation parts and
A limit determination including a determination as to whether or not each of the left and right required torques calculated by the second calculation unit exceeds a predetermined torque upper limit value is performed to determine whether or not the required torque difference can be realized. Limit judgment unit and
When the limit determination unit determines that the required torque difference cannot be realized, the turning determination unit determines whether or not the vehicle is understeer.
When the turning determination unit determines that the vehicle is understeer, the required torque on the left and right is recalculated, and the torque difference is insufficient to realize the required torque difference between the left and right wheels. The third calculation unit that calculates the minute as the brake amount of the vehicle,
A motor control unit that controls the two motors based on the left and right required torques calculated by the third calculation unit.
A four-wheel drive vehicle control device including a brake control unit that controls a brake pressure based on the brake amount calculated by the third calculation unit. The four-wheel drive vehicle control device according to claim 1, wherein the limit determination includes determination of whether or not the required torque difference exceeds a predetermined torque difference upper limit value. When the left and right required torques are recalculated, the third calculation unit calculates so that the sum of the left and right required torques becomes the one required torque of the front and rear wheels calculated by the first calculation unit. The four-wheel drive vehicle control device according to claim 1 or 2. The four-wheel drive vehicle control device according to any one of claims 1 to 3, wherein the turning determination unit determines whether or not understeer occurs at the time of turnout of the vehicle. The control device is
A drive source control unit that controls the drive source,
When the turning determination unit determines that the vehicle is not understeer, the fourth calculation unit recalculates the left and right required torques and adds the insufficient torque difference to the other required torques of the front and rear wheels. And, with more
When recalculated by the fourth calculation unit, the motor control unit controls the two motors based on the left and right required torques calculated by the fourth calculation unit.
The drive source control unit is characterized in that, when recalculated by the fourth calculation unit, the drive source control unit controls the drive source based on the other required torque calculated by the fourth calculation unit. The four-wheel drive vehicle control device according to claim 4. When the limit determination unit determines that the required torque difference cannot be realized, the turning determination unit skips the determination of whether or not the vehicle is understeer when the vehicle is turning in or cornering. ,
Even if the determination is skipped by the turning determination unit, the fourth calculation unit adds the insufficient torque difference to the other required torque of the front and rear wheels, and recalculates the left and right required torques. 5. The four-wheel drive vehicle control device according to claim 5. The four-wheel drive vehicle control device according to any one of claims 1 to 6, wherein the two motors drive the rear wheels and the drive source drives the front wheels.

Images