JP5435162B2 - Control device for right / left driving force adjusting device for vehicle - Google Patents

Description

  The present invention relates to a control device for a left / right driving force adjusting device for a vehicle.

  2. Description of the Related Art Conventionally, a vehicle left / right driving force adjusting device that adjusts the driving force of left and right wheels of a vehicle is known. The left / right driving force adjusting device for a vehicle has, for example, a differential gear and a driving force adjusting mechanism between the left and right wheels. As one of the driving force adjustment mechanisms, an electric active yaw control (hereinafter referred to as electric AYC) having an electric motor and a gear mechanism is known. By controlling the electric motor by a control device, The distribution of driving force to the wheels is adjusted. And in the said control apparatus, the stability restriction | limiting of a vehicle attitude | position is aimed at by performing differential restriction | limiting of the motor torque of an electric motor, for example, the technique of patent document 1 is known.

JP 2006-046495 A

In Patent Document 1 (particularly, refer to paragraphs 0046 to 0050, FIG. 12 and the like), as a method of performing differential limiting of motor torque, actual torque T _real calculated from motor current and differential limiting torque T _lim are compared, When the actual torque T _real is larger, the motor current is gradually reduced. In this method, the electric motor is controlled based on the previously calculated control amount, the actual torque T _real is obtained from the motor current generated as a result of controlling the electric motor, and the actual torque T _real is compared with the differential limit torque T _lim. doing. That is, in this method, the differential limiting torque T _lim does not function as an absolute limiting value, and after the actual torque T _real ≧ differential limiting torque T _lim (after once overshooting), the motor Since control for gradually reducing the current is started, the actual torque T _real may greatly exceed the differential limit torque T _lim (see graphs of FIGS. 5A and 5B described later).

When the actual torque T _real is larger than the differential limiting torque T _lim , the motor current is gradually reduced. However, when the current decrease gradient during the control is small, the actual motor current is Convergence to the target will be delayed, drag will occur, and there is concern about feeling and fuel consumption deterioration. For example, FIG. 5 (a) shows a comparison between a mechanical differential limiting device and an electric AYC (when the current decrease gradient of the electric motor is small), but the mechanical type for the rotational speed difference between the left and right wheels (solid line graph). A follow-up delay occurs in the change in the differential torque of the electric AYC (indicated by the dashed line) relative to the change in the differential torque of the differential limiting device (indicated by the dotted line).

  On the other hand, when the current decrease gradient during the control of the motor current is large, vibration occurs in the target motor current, and torque fluctuation occurs due to the vibration of the target motor current. As a result, vibration is generated in the vehicle, and there is a concern that the feeling may deteriorate or abnormal noise may occur. For example, FIG. 5B shows a comparison between a mechanical differential limiting device and an electric AYC (when the electric motor has a large current decrease gradient), but the mechanical type for the rotational speed difference between the left and right wheels (solid line graph). In contrast to the change in the differential torque of the differential limiting device (dotted line graph), vibration occurs in the change in the differential torque of the electric AYC (dotted line graph).

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a control device for a left / right driving force adjusting device for a vehicle that improves the convergence and response of the control and improves the stability of the vehicle posture. .

A control device for a left / right driving force adjusting device for a vehicle according to a first aspect of the present invention for solving the above-described problem is provided.
A left and right driving force adjusting device for a vehicle that has a motor that generates a torque difference between the left and right wheels of the vehicle, and controls the attitude of the vehicle using the motor;
A control device for controlling the motor,
The control device includes:
While detecting the actual rotational speed difference between the left and right wheels, the target rotational speed difference is calculated based on the vehicle speed and the steering angle of the vehicle,
Calculating a target torque difference that causes the actual rotational speed difference to follow the target rotational speed difference;
Based on the operation state of the driver, the maximum differential limit torque that limits the maximum value of the target torque difference is calculated,
A limit torque difference obtained by limiting the target torque difference based on the maximum differential limit torque is calculated,
The motor is controlled so as to achieve the differential torque difference, and differential limitation is performed.

  In other words, in the first aspect of the invention, in the control device (electric AYC) for the vehicle left-right driving force adjusting device having the above-described configuration, the target torque is output at a stage before outputting the control value (limit torque difference) for controlling the motor. The difference is limited based on the torque difference upper limit value, and the limited value is used as the control value (limit torque difference). Therefore, a control value exceeding the control value (limit torque difference) is not output. Differential limiting similar to a limiting device (for example, an electronically controlled LSD (Limited Slip Differential Gear) or the like) can be performed.

A control device for a vehicle left-right driving force adjusting device according to a second invention for solving the above-described problems
In the control device for a vehicle left-right driving force adjusting device according to the first invention,
The control device includes:
The maximum differential limiting torque is calculated using a first map in which the maximum differential limiting torque increases in accordance with an increase in the driver's acceleration request.
A control device for a left / right driving force adjusting device for a vehicle according to a third invention for solving the above-described problem is
In the control device for a vehicle left-right driving force adjusting device according to the second invention,
The control device includes:
A correction coefficient for correcting the maximum differential limiting torque is calculated using a second map in which the correction coefficient decreases from 1 to 0 in accordance with an increase in the absolute value of the steering angle;
The maximum differential limit torque and the correction coefficient are integrated to calculate a torque difference upper limit value for limiting the target torque difference,
The target torque difference is limited based on the torque difference upper limit value, and the limit torque difference is calculated.

  According to the present invention, even if high gain follow-up control is performed and the target torque difference with respect to the target rotational speed difference is calculated, the upper limit of the calculated target torque difference is limited, and the motor torque based on the limited torque difference is used. Since the motor is controlled, the response of the motor torque and the convergence to the target value are improved, and the stability and the traction performance can be improved. As a result, an effect equivalent to the preload (initial torque) control performed by the electronic control LSD can be expected, and even when the target rotational speed difference is set to 0, the same effect as the electronic control LSD can be obtained. Stability is improved.

  In addition, according to the present invention, since the target rotational speed difference calculated from the vehicle speed and the steering angle is used, the differential limiting torque difference acts as much as the actual vehicle body posture deviates from the target vehicle body posture, and smooth turning and excellent Stable stability.

It is a schematic structure figure explaining an example of an embodiment of a control device of a right-and-left driving force adjustment device for vehicles concerning the present invention. It is a block diagram explaining the control apparatus of the left-right driving force adjusting device for vehicles shown in FIG. FIG. 2 is a map used in the control device of the left / right driving force adjusting device for a vehicle shown in FIG. 1, where (a) calculates a maximum differential limiting torque with respect to driving torque, and (b) shows a correction coefficient for a steering angle. It is to calculate. It is a flowchart in the control apparatus of the left-right driving force adjusting device for vehicles shown in FIG. It is a graph which shows the comparison of the differential torque of a mechanical differential limiting device and electric AYC, (a) is when the electric current motor's electric current decrease gradient is small, (b) is the electric motor's electric current decrease gradient is large. Is the case.

  Hereinafter, with reference to FIGS. 1-4, an example of embodiment of the control apparatus of the left-right driving force adjusting device for vehicles which concerns on this invention is demonstrated.

Example 1
FIG. 1 is a schematic configuration diagram illustrating a control device for a left / right driving force adjusting device for a vehicle according to the present embodiment. 2 is a block diagram for explaining the control device shown in FIG. 1, FIG. 3 is a map used in the control device shown in FIG. 1, and FIG. 4 is a map in the control device shown in FIG. It is a flowchart.

  As shown in FIG. 1, the vehicle left / right driving force adjusting device transmits an output from a prime mover 11 such as an engine or a motor to the left wheel 12 and the right wheel 13 as a driving force, and rotates the left wheel 12 and the right wheel 13. A differential gear 14 that adjusts the number difference and a driving force adjusting mechanism 15 that adjusts the distribution of the driving force to the left wheel 12 and the right wheel 13 are provided between the left wheel 12 and the right wheel 13. The driving force adjusting mechanism 15 includes an electric motor 16 and a gear mechanism 17 that generate a torque difference between the left wheel 12 and the right wheel 13 by output torque. The electric motor 16 is an ECU (control device) 20. Controlled by This is a so-called electric AYC, which functions as an actuator that generates a yaw moment for controlling the attitude of the vehicle. By controlling the electric motor 16 by the ECU 20, the left and right wheels 12 and 13 are connected to the right wheel 13. The distribution of driving force is adjusted.

  Note that, for example, a bevel gear type is used as the differential gear 14, but the configuration of the differential gear 14 is not directly related to the present invention, and a detailed description thereof will be omitted.

  The gear mechanism 17 adjusts the distribution amount of the driving force transmitted to the left wheel 12 and the right wheel 13 together with the electric motor 16, but the configuration itself of the gear mechanism 17 is also directly related to the present invention. Since it is not a part to do, the detailed description is abbreviate | omitted.

  The left wheel 12 and the right wheel 13 to be controlled may be front wheels only, rear wheels only, or all four wheels, but in this embodiment, the description will be made assuming that the control objects are only rear wheels.

  Next, the function of the ECU 20 will be described with reference to FIGS.

  The ECU 20 includes a target rotational speed difference tracking control unit B1 (target rotational speed difference calculating means B2, actual left and right wheel rotational speed difference detecting means B3, target rotational speed difference tracking control means B4), torque difference upper limit value calculating means B5, It has a limiter B6, a torque difference / motor torque conversion means B7, and a motor control means B8.

The target rotational speed difference calculating means B2 calculates the target rotational speed difference according to the vehicle state and the driver's operation state. Specifically, based on the vehicle speed and steering angle detected by a vehicle speed sensor that detects the vehicle speed and a steering angle sensor that detects the steering angle of the steering (both not shown), the vehicle speed and steering angle are expressed as shown in the following formula. The target rotational speed difference is obtained by the function F1 as a variable.
Target speed difference = F1 (vehicle speed, steering angle)
Note that the target rotational speed difference is 0 when the vehicle is running straight.

The actual left and right wheel rotational speed difference detecting means B3 detects the rotational speed difference between the left wheel 12 and the right wheel 13 of the vehicle. Specifically, based on the actual left wheel rotation speed and the actual right wheel rotation speed detected by the wheel speed sensor (not shown) of each wheel, as shown in the following equation, the actual right wheel rotation speed and the actual left wheel rotation speed The difference between the actual left and right wheel rotational speeds is obtained from the difference between the two.
Difference between actual left and right wheel rotation speed = actual right wheel rotation speed-actual left wheel rotation speed Based on the actual motor rotation speed detected by the electric motor 16, the actual left and right wheel rotation speed difference is obtained as shown in the following equation. May be.
Difference between actual left and right wheel speed = actual motor speed x coefficient

The target rotational speed difference tracking control means B4 calculates a target torque difference for performing tracking control of the actual left and right wheel rotational speed difference to the target rotational speed difference. Specifically, based on the deviation between the target rotational speed difference obtained by the target rotational speed difference calculation means B2 and the actual left and right wheel rotational speed difference detection means B3, as shown in the following equation: Then, the target torque difference is obtained by PID control.
Target torque difference = PID (target speed difference-actual left and right wheel speed difference)
Note that the target torque difference is not limited to PID control, but may be obtained by other control methods such as H∞ control, fuzzy control, and the like. However, in this embodiment, the gain is set high in order to increase the responsiveness no matter what control is used.

  Accordingly, the target rotational speed difference follow-up control unit B1 obtains the target torque difference based on the target rotational speed difference and the actual left and right wheel rotational speed difference, and the obtained target torque difference is a torque difference upper limit value described later. It is limited by the torque difference upper limit value obtained by the calculation means B5.

  The torque difference upper limit calculating means B5 calculates a torque difference upper limit value for the target torque difference calculated by the target rotation speed difference tracking control unit B1 based on the vehicle state and the driver's operation state. Specifically, the torque difference upper limit value is calculated using the maps shown in FIGS. 3 (a) and 3 (b).

  A map 1 (first map) shown in FIG. 3A is a map for calculating the maximum differential limiting torque that limits the maximum value of the target torque difference based on the driving torque that is the driver's acceleration request. The maximum differential limiting torque is increased in proportion to the increase in drive torque (for example, engine output torque × total reduction ratio). Further, as shown in a map 2 in FIG. 3B described later, when the absolute value of the steering angle is 0, the correction coefficient for the maximum differential limiting torque is 1. A map 1 shown in FIG. 3A is obtained when the absolute value of the steering angle is 0, and is a maximum value that limits the target torque difference. In addition, what is necessary is just to obtain | require drive torque using a known method.

  In place of the drive torque, the maximum differential limit torque may be calculated based on the accelerator opening that is the driver's acceleration request, and the map in that case is also proportional to the increase in the accelerator opening, The maximum differential limit torque is increased. The accelerator opening is detected using an accelerator opening sensor (not shown).

  A map 2 (second map) shown in FIG. 3B is a map for calculating a correction coefficient for correcting the maximum differential limiting torque calculated in the map 1 based on the steering angle detected by the steering angle sensor. The correction coefficient is decreased from 1 to 0 in proportion to the increase in the absolute value of the steering angle. When the absolute value of the steering angle is larger than a predetermined value, the correction coefficient is set to 0.

Then, in the torque difference upper limit calculating means B5, as shown in the following equation, the torque difference upper limit value is obtained by adding the correction coefficient calculated in map 2 to the maximum differential limiting torque calculated in map 1. .
Torque difference upper limit = (maximum differential limiting torque of MAP1) × (correction coefficient of MAP2)

In the limiter B6, the absolute value of the target torque difference input from the target rotational speed difference tracking control unit B1 is limited based on the torque difference upper limit value calculated by the torque difference upper limit value calculation means B5, and is output. Specifically, a limiter output (limit torque difference) obtained by limiting the upper limit of the absolute value of the target torque difference with the torque difference upper limit value is calculated using the following equation.
Limiter output = max {(−torque difference upper limit value), min (torque difference upper limit value, target torque difference)}

In the torque difference / motor torque converting means B7, the limiter output (limit torque difference) output from the limiter B6 is converted into motor torque using the following equation.
Motor torque = limiter output × conversion coefficient For example, [1 / (2G)] is used as the conversion coefficient. Here, G is expressed as G = N _m / ΔN using the motor rotation speed N _m and the rotation speed difference ΔN between the left and right wheels.

  The motor control means B8 controls the electric motor 16 so that the converted motor torque is obtained. In the present embodiment, by controlling the electric motor 16 using the motor torque, differential limitation is performed during vehicle attitude control.

  Here, along with the flowchart shown in FIG. 4, with reference also to FIGS.

  The actual left wheel rotation speed and the actual right wheel rotation speed or the actual motor rotation speed is detected (step S1; see the actual left and right wheel rotation speed difference detection means B3 in FIG. 2).

  An actual left and right wheel rotation speed difference is calculated using the actual left wheel rotation speed and the actual right wheel rotation speed detected in step S1 or the actual motor rotation speed (step S2; actual left and right wheel rotation speed difference detection means in FIG. 2). (See B3).

  Based on the vehicle state (vehicle speed) and the driver's operation state (steering angle), the target rotational speed difference is calculated (step S3; see target rotational speed difference calculating means B2 in FIG. 2).

  Based on the actual left and right wheel rotational speed difference calculated in step S2 and the target rotational speed difference calculated in step S3, a deviation between them is calculated (step S4; see target rotational speed difference tracking control means B4 in FIG. 2).

  Using the deviation calculated in step S4, a target torque difference for controlling the actual left and right wheel rotational speed difference to follow the target rotational speed difference is calculated (step S5; see target rotational speed difference tracking control means B4 in FIG. 2). . For example, the target torque difference may be obtained by PID control.

  Based on the driver's operation state (drive torque (or accelerator opening), steering angle), a torque difference upper limit value for the target torque difference calculated in step S5 is calculated (step S6; torque difference upper limit value in FIG. 2). (See calculation means B5 and maps 1 and 2 in FIGS. 3A and 3B). At this time, the maximum differential limit torque that limits the maximum value of the target torque difference is calculated based on the drive torque or the accelerator opening, and the correction coefficient that corrects the maximum differential limit torque is calculated based on the steering angle. The torque difference upper limit value is obtained by adding the correction coefficient to the maximum differential limit torque.

  Limiter processing is performed to limit the absolute value of the target torque difference value calculated in step S5 to be equal to or less than the torque difference upper limit value calculated in step S6 (step S7; see limiter B6 in FIG. 2).

  The torque difference (limit torque difference) subjected to the limiter process is converted into a motor torque output by the electric motor 16 (step S8; see torque difference / motor torque conversion means B7 in FIG. 2).

  The electric motor 16 is controlled so as to output the motor torque converted in step S8, and differential restriction is performed during vehicle attitude control (step S9; see motor control means B8 in FIG. 2).

  Even if the target torque difference with respect to the target rotational speed difference is calculated by performing the high gain follow-up control by the above-described control, the upper limit of the calculated target torque difference is limited, and the motor torque based on the limited torque difference is used. Since the electric motor 16 is controlled, the responsiveness of the motor torque and the convergence to the target value are improved, and the stability and the traction performance can be improved. As a result, the same effect as the preload control performed by the electronic control LSD can be expected, and even when the target rotational speed difference is set to 0, the same effect as the electronic control LSD can be obtained, so that the straight running stability is improved. To do. That is, in the electric AYC, the same differential limitation as that of a mechanical differential limiting device such as an electronic control LSD can be performed. In the above-described control of this embodiment, for example, as shown in FIGS. Control such as differential torque (see the dotted line graph) of the mechanical differential limiting device can be performed.

  In the above-described control, since the target rotational speed difference calculated from the vehicle speed and the steering angle is used, the torque difference of the differential limit acts as much as the actual vehicle body posture deviates from the target vehicle body posture, and smooth turning and excellent Both stability can be achieved.

  The present invention is suitable for a control device for a left / right driving force adjusting device for a vehicle that uses an electric motor to adjust the driving force of the left / right wheels of the vehicle.

11 prime mover 12 left wheel 13 right wheel 14 differential gear 15 driving force adjustment mechanism 16 electric motor 17 gear mechanism 20 ECU

Claims (3)

A left and right driving force adjusting device for a vehicle that has a motor that generates a torque difference between the left and right wheels of the vehicle, and controls the attitude of the vehicle using the motor;
A control device for controlling the motor,
The control device includes:
While detecting the actual rotational speed difference between the left and right wheels, the target rotational speed difference is calculated based on the vehicle speed and the steering angle of the vehicle,
Calculating a target torque difference that causes the actual rotational speed difference to follow the target rotational speed difference;
Based on the operation state of the driver, the maximum differential limit torque that limits the maximum value of the target torque difference is calculated,
A limit torque difference obtained by limiting the target torque difference based on the maximum differential limit torque is calculated,
A control device for a vehicle left-right driving force adjusting device, wherein the motor is controlled to perform differential limitation so that the torque limit difference is obtained. In the control device for a vehicle left-right driving force adjustment device according to claim 1,
The control device includes:
A left and right driving force adjusting device for a vehicle, wherein the maximum differential limiting torque is calculated using a first map in which the maximum differential limiting torque increases in accordance with an increase in a driver's acceleration request. Control device. The control device for a vehicle left-right driving force adjustment device according to claim 2,
The control device includes:
A correction coefficient for correcting the maximum differential limiting torque is calculated using a second map in which the correction coefficient decreases from 1 to 0 in accordance with an increase in the absolute value of the steering angle;
The maximum differential limit torque and the correction coefficient are integrated to calculate a torque difference upper limit value for limiting the target torque difference,
A control device for a vehicle left-right driving force adjusting device, wherein the target torque difference is limited based on the torque difference upper limit value and the limit torque difference is calculated.

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