Control device for a left / right drive force adjusting device of a vehicle

Abstract

A control device calculates a control amount that makes an actual vehicle stability follow a target vehicle stability calculated based on a vehicle state or an operating state, changes a distribution rate of the control amount to the motor and the brake device depending on increase and decrease of the charging rate of the secondary battery, and controls the motor and the brake device by the distributed control amount, thereby performing stability control of a vehicle.

Description

The present invention relates to a control device that controls a left / right vehicle driving force adjusting device.Heretofore, there has been known a left / right vehicle driving force adjusting device which adjusts the driving force of a left wheel and a right wheel of a vehicle. A left / right vehicle driving force adjusting device has a differential gear and a driving force adjusting mechanism between the left wheel and right wheel, and is capable of adjusting the distribution of the driving force to the left wheel and right wheel by controlling the driving force adjusting mechanism. As a driving force adjustment mechanism, a mechanism using a clutch mechanism, a brake device, an electric motor, or the like is known. Among them, a mechanism using the electric motor is referred to as Active Yaw Control (Active Yaw Control) (hereinafter referred to as Electric AYC), and adjusts the distribution of the driving force to the left wheel and the right wheel by controlling the electric motor.Referring to FIG. 5, in a left / right vehicle driving force adjusting device using an electric motor, it is configured such that electric power from a secondary battery 31, e.g., a lithium ion battery, is converted into a three-phase alternating current by, e.g., an electric power converting device 32, and the converted three-phase alternating current is supplied to a three-phase motor 34 of an electric AYC 33. Here, the electric power P to be consumed by the electric AYC 33 may be expressed by the following equation. This also applies to the case of electricity generation described later.Tm is an engine torque, Nm is an engine speed, ΔT is a torque difference, and ΔN is a rotational speed difference between left and right wheels.In a case where the attitude control of a vehicle is performed by the electric AYC 33 during traction drive, upon generation of a rotation promoting torque (a rotational speed difference is amplified) for rotation promoting control to control a three-phase motor 34 in a power-exerting manner, the three-phase motor 34 consumes the electric power P. On the other hand, the three-phase motor 34 generates the electric power P upon generation of the rotation suppressing torque (the rotational speed difference is reduced) for rotation suppressing control to control the three-phase motor 34 in a power-restoring manner. Thus, in the electric AYC 33, when the electric power P is consumed, the electric power is supplied from the secondary battery 31, and when the electric power P is generated, the charging of the secondary battery 31 is performed. Patent Document 5 relates to a vehicle behavior control apparatus. Patent Document 6 relates to a transmission for an automobile having a rotatable differential carrier and two output shafts. Patent Document 7 relates to a hybrid vehicle (HV) and a control method thereof.Patent Document 1: JP 3 686 626 B2Patent Document 2: JP 2006-46 495 APatent Document 3: JP 2006-57 745 APatent Document 4: JP 2003-335 143 APatent Document 5: JP 2009-143 432 APatent Document 6: DE 10 2006 058 835 A1Patent Document 7: DE 696 10 360 T2In a case where the stability control of a vehicle is performed using the electric AYC 33 of FIG. 5, when a charge rate of the secondary battery 31 is 100%, since the charging of the secondary battery 31 is impossible, the electric AYC 33 cannot perform the rotation suppression control. On the other hand, when the charge rate of the secondary battery 31 is 0%, since the electric power is not taken out from the secondary battery 31, the electric AYC 33 cannot perform the rotation feed control.Moreover, as the driving force adjusting mechanism, there is also a left / right driving force adjusting device of a vehicle that performs the attitude control of a vehicle by a brake device. However, in this case, since kinetic energy of a vehicle is consumed by the warming of the brake, there is a problem that fuel consumption increases and a driver feels a feeling of discomfort as a result of the deceleration of the brake. The present invention is defined in the claims.An advantage of some aspects of the invention is to provide a control device of a left / right driving force adjusting device of a vehicle that always performs the attitude control regardless of a charge rate of a secondary battery and performs the attitude control without feeling uncomfortable due to the deceleration.According to an aspect of the invention, there is provided a control device for controlling a left / right driving force setting device of a vehicle, the left / right driving force setting device of a vehicle including: a brake device that applies a braking force to a left wheel and a right wheel of a vehicle, respectively; a motor that generates a torque difference between the left wheel and the right wheel; and a secondary battery that is capable of supplying electric power to the motor and that is capable of charging electric power generated by the motor and that is configured to perform posture control of a vehicle using the brake device and the motor, the control device including:a calculating means calculating a control amount that makes an actual vehicle posture follow a target vehicle posture calculated based on a vehicle state and / or an operating state; anda posture controller that changes a distribution rate of the control amount to the motor and the brake device depending on increase and decrease of a charge rate of the secondary battery, and controls the motor and the brake device by the distributed control amount, thereby performing posture control of the vehicle.Further, the control device may include determination means that determines whether an operation of the motor by the calculated control amount is a power restoration by the motor or a power exercise by the motor.In the control device, when the determination means determines that the operation of the motor is the performance restoring, the attitude control means decreases the distribution rate of the control amount to the motor and increases the distribution rate of the control amount to the brake device depending on an increase in the charging rate of the secondary battery, and controls the motor by the distributed control amount, thereby performing attitude control of the vehicle.Further, when the determination means determines that the operation of the motor is the output, the attitude control means decreases the distribution rate of the control amount to the motor and increases the distribution rate of the control amount to the brake device depending on a decrease in the charging rate of the secondary battery, and controls the motor or the brake device by the distributed control amount, thereby performing attitude control of the vehicle.The control device may be configured such that: when it is determined by the determination means that the operation of the engine is the performance restoration, the attitude control means sets the distribution rate to the engine to 0% and sets the distribution rate to the brake device to 100% and controls only the brake device, thereby performing attitude control of the vehicle, in a first state in which the charging rate is nearly 100%, and the attitude control means sets the distribution rate to the engine to 0% and sets the distribution rate to the brake device to 100% and controls only the brake device, in a second state in which the charging rate is nearly 0%, the attitude control means sets the distribution rate to the engine to 100% and controls only the brake device, whereby attitude control of a vehicle is performed.The control device may be configured such that: a maximum charging rate in the first state is a charging rate at which the secondary battery is overcharged by electricity generation of the motor and is less than 100%; and a minimum charging rate in the second state is a charging rate at which the charging rate becomes 0% due to electric power consumption of the motor and is greater than 0%.According to the present invention, the control amount (a torque difference) that performs the attitude control of a vehicle is distributed into the AYC motor and the brake device depending on the charging rate of the secondary battery, whereby the attitude control of the vehicle can be always performed regardless of the charging rate of the secondary battery.Further, according to the present invention, the stability control of the vehicle is performed to the utmost by means of the AYC electric motor, whereby the efficiency can be improved without consuming the kinetic energy of the vehicle or increasing the fuel consumption, and it is possible to perform the control without feeling uncomfortable due to the deceleration. FIG. 1 is a schematic circuit diagram explaining an example of an embodiment of a control device of a left / right vehicle driving force adjusting device according to the present invention. FIG. 2 is a block diagram explaining the control device of the left / right vehicle driving force setting device of FIG. 1. FIG. 3 is a flow chart in the control device in the left / right vehicle driving force setting device of FIG. 1. FIG. 4A is a map used in performance restoration in the control device of the left / right vehicle driving force setting device of FIG. 1. FIG. 4B is a map used when power is applied in the control device of the left / right vehicle driving force setting device of FIG. 1. FIG. 5 is a block diagram explaining a configuration between a secondary battery and an electric AYC.An example of an embodiment of a control device of a left / right vehicle driving force adjusting device according to the present invention will be described below with reference to FIGS. 1 to 4B.FIG. 1 is a schematic circuit diagram explaining a control device of a left / right vehicle driving force setting device of this embodiment. FIG. 2 is a block diagram explaining the control device of the left / right vehicle driving force setting device of FIG. 1. Further, FIG. 3 is a flow chart in the control device of the left / right vehicle driving force setting device of FIG. 1, FIG. 4A is a performance restoration map used in the control device of the left / right vehicle driving force setting device of FIG. 1. FIG. 4B is a performance characteristic map.In this example, the left / right vehicle driving force adjusting device is connected to a differential gear 11 via a transmission mechanism 12 and includes an AYC electric motor 15 that generates a torque difference between a left wheel 13 and a right wheel 14 by an output torque, brake devices 16 and 17 that give the braking force to the left wheel 13 and the right wheel 14, respectively, and a secondary battery 19 that supplies electric power to the AYC electric motor 15 via an electric power conversion device 18 and charges the electric power generated by the AYC electric motor 15. In addition, an ECU (a control device) 20 controls the AYC electric motor 15, the brake devices 16 and 17, and the secondary battery 19.In this way, in this embodiment, the left / right vehicle driving force adjusting device is configured to have the electric AYC (the transmission mechanism 12 and the AYC electric motor 15) which becomes an actuator that generates a yaw moment, and the brake devices 16 and 17 for attitude control of a vehicle.In addition, the transmission mechanism 12 regulates the distribution amount of the driving force transmitted to the left wheel 13 and the right wheel 14 together with the AYC electric motor 15.Further, the differential gear 11 adjusts a rotational speed difference between the left wheel 13 and the right wheel 14, and transmits the output from a main engine 22, e.g., an internal combustion engine or an electric motor, to the left wheel 13 and the right wheel 14 as a driving force. As the differential gear 11, for example, one of the bevel type is used. Since the configuration of the differential gear 11 itself is not a part directly related to the invention, its detailed description is omitted.Further, the left wheel 13 and the right wheel 14 that become control targets are front wheels in this embodiment, but may be rear wheels or all four wheels. In addition, the brake devices 16 and 17 may use any one as long as they can cause the left wheel 13 and the right wheel 14 to brake, respectively, but a hydraulic brake device will be described as an example in this embodiment.Next, the operation of the ECU 20 will be described with reference to FIGS. 1, 2, 4A, and 4B.The ECU 20 has a vehicle stability control amount calculation means B 1, a power restoration / performance requirement determination means B 2, and a vehicle stability control means. The vehicle posture control means includes a control amount distribution means B3, a torque difference-to-AYC motor torque conversion means B4, a torque difference-to-brake hydraulic conversion means B5, a brake operation wheel determination means B6, an AYC motor control means B7, and a brake control means B8.The vehicle stability control amount calculating means B1 calculates a control amount for performing the attitude control of a vehicle, i.e., a torque difference, depending on an input sensor value A1. Here, the torque difference generating a yaw moment is calculated so that an actual yaw rate follows a target yaw rate. The rotation is suppressed or damped or promoted by the calculated torque difference. As the sensor value A 1, a vehicle speed, a steering angle, and an actual yaw rate are input from a sensor group 23. Also, the target yaw rate can be obtained by a function F 1 (the vehicle speed and the steering angle) based on the input vehicle speed and the steering angle, and the torque difference can be obtained by PID control based on the input actual yaw rate and the obtained target yaw rate. In addition, the torque difference may be obtained by other control methods, for example, H-and-End control, invalidation control, or the like, without being limited to the PID control.The power restoration / exertion determining means B2 determines whether the AYC electric motor 15 performs the power restoration or exertion depending on the direction of the yaw moment generated by the torque difference and the AYC electric motor rotational speed of the input sensor value A2. In addition, the AYC motor speed of the sensor value A2 also includes information on the rotational direction. For example, if signs of a counter-clockwise yaw rate, the yaw moment, and the yaw moment generating torque difference are positive, and if the sign of the rotational direction of the AYC motor 15 during the traction drive rotation is positive, a case "(torque difference) x (AYC motor rotational speed)≥0" is determined as a power duty, and the remaining case is determined as a power restoration.The control amount distribution means selects a distribution rate calculation map depending on the power application and the power restoration, and calculates the distribution rate of the torque difference to be distributed to the AYC electric motor 15 and the brake devices 16 and 17 based on the secondary battery charge rate of the input sensor value A3, thereby obtaining the electric AYC distribution amount and the brake device distribution amount.Referring to FIGS. 4A and 4B, a torque difference distribution rate calculation map is switched in the performance restoration and the performance exercise.Specifically, in the secondary battery 19, when power is recovered as shown in FIG. 4A, in the range of the charge rate from 0% to C 1%, the distribution rate to the electric AYC side is 100% and the distribution rate to the brake side is 0%. In addition, when the charging rate is at least C 1%, in the range of the charging rate from C 1% to C 2%, in proportion to a charging rate increase, the distribution rate to the electric AYC side is decreased and the distribution rate to the brake side is increased. In addition, when the charging rate is at least C 2%, the distribution rate to the electric AYC side is 0% and the distribution rate to the brake side is 100%. In addition, C1 is lower than C2. In this embodiment, C1 is set in a range of 60% to 85%, and C2 is set in a range of 70% to 95%.In this way, when power is recovered in a region of C 1% charging rate or less in which the charging rate of the secondary battery 19 is not high, the torque difference is distributed only to the electric AYC side, and only the AYC electric motor 15 is used. Further, in a range of C 1% to C 2% charging rate in which the charging rate is relatively high depending on the charging rate, the torque difference is distributed to the electric AYC side and the brake side, and the AYC electric motor 15 and the brake devices 16 and 17 are commonly used. In a region of C 2% charging rate or more in which the charging rate is much higher, the torque difference is distributed only to the brake side, and only the brake devices 16 and 17 are used. C 2% is the charge rate at which the secondary battery 19 is overcharged by the electricity generation of the AYC electric motor 15.By using the performance restoration map, in the range of C 2% charging rate or more in which the charging rate of the secondary battery 19 is sufficiently high, the attitude control of a vehicle can be performed by using only the brake devices 16 and 17. In addition, within the range of 0% to C 2% charging rate by using only the AYC electric motor 15 or using the AYC electric motor 15 and the brake devices 16 and 17 together, the attitude control of a vehicle is performed by using the AYC electric motor 15 all at once. Thereby, the efficiency can be improved without consuming the kinetic energy of a vehicle or increasing the fuel consumption, which makes it possible to perform the attitude control without feeling uncomfortable due to the deceleration.On the other hand, when power is applied as shown in FIG. 4B, in the secondary battery 19, in the range of 100% to C3% charge rate, the distribution rate to the electric AYC side is 100% and the distribution rate to the brake side is 0%. Further, when the charging rate is C 3% or less, in the range of C 3% to C 4% charging rate in proportion to a charging rate decrease, the distribution rate to the electric AYC side is decreased and the distribution rate to the brake side is increased. Further, when the charging rate is C 4% or less, the distribution rate to the electric AYC side is 0% and the distribution rate to the brake side is 100%. In addition, C4 is lower than C3 and C3 is lower than C1. In this embodiment, C3 is set in a range of 15% to 40%, and C4 is set in a range of 5% to 30%.In this way, when power is applied in a range with at least C 3% charging rate in which the charging rate of the secondary battery 19 is not low, the torque difference is distributed only to the electric AYC side, and only the AYC electric motor 15 is used. In addition, in a range of C 3% to C 4% charging rate in which the charging rate is relatively low depending on the charging rate, the torque difference is distributed to the electric AYC side and the brake side, and the AYC electric motor 15 and the brake devices 16 and 17 are commonly used. In a region of at most C 4% charging rate in which the charging rate is much lower, the torque difference is distributed only to the brake side, and only the brake devices 16 and 17 are used. C 4% is the charge rate at which the charge rate becomes 0% due to the electric power consumption of the AYC electric motor 15.By using the output characteristic map, in the range of at most C 4% charging rate in which the charging rate of the secondary battery 19 is sufficiently low, the attitude control of a vehicle can be performed by using only the brake devices 16 and 17. In addition, in the range of 100% to C4% charging rate, only the AYC electric motor 15 is used, or the AYC electric motor 15 and the brake devices 16 and 17 are used together. Thus, since the attitude control of a vehicle is performed by the AYC electric motor 15 all the way round, the efficiency can be improved without consuming the kinetic energy of a vehicle or increasing the fuel consumption, which makes it possible to perform the attitude control without feeling uncomfortable due to the deceleration.In addition, the electric AYC distribution amount and the brake device distribution amount are obtained from the following equation.The torque difference-to-AYC motor torque conversion means B4 converts the distributed torque difference, i.e., the obtained electric-AYC distribution amount, into the AYC motor torque. The AYC motor torque is converted using the following equation.Here, G is represented by G=Nm / ΔN using an engine speed Nm and a speed difference ΔN between the left wheel and the right wheel.The torque difference-to-brake hydraulic converting means B5 converts the distributed torque difference, i.e., the obtained brake device distribution amount, into brake hydraulics that operate the brake devices 16 and 17. The brake hydraulics are converted by the following equation.The brake device operating wheel determining means B6 determines which vehicle wheel brake, i.e., which of the brake devices 16 and 17, is operated based on the distributed torque difference, i.e., the obtained brake device distribution amount.The AYC motor controller B 7 controls the AYC motor 15 so that the input motor torque value is output.The brake control means B8 controls the brake devices 16 and 17 depending on the vehicle wheel to which the control is applied and the input brake hydraulics.Next, the control flow in the ECU 20 according to the flowchart of FIG. 3 will be explained with simultaneous reference to FIGS. 1, 2, 4A, and 4B.First, based on the detected vehicle speed (the vehicle state) and / or the detected steering angle (operating state), a target yaw rate (a target vehicle posture) is calculated depending on the vehicle speed and / or the steering angle (step S 1; see the vehicle stability control amount calculator B 1 of FIG. 3 ).Next, based on the detected actual yaw rate (an actual vehicle posture), a torque difference (a control amount) that generates a yaw moment is calculated so that the target yaw rate follows the actual yaw rate (step S 2; see the vehicle stability control amount calculator B 1 of FIG. 3 ). The torque difference is obtained by feedback control of the yaw rate by the PID control or the like, for example.Subsequently, it is determined whether the operation state of the AYC electric motor 15 becomes the power restoration or the power exercise from the AYC electric motor rotational speed including information on the direction of the yaw moment generated by the calculated torque difference and the detected rotational direction (step S 3; see the power restoration / exercise determiner B 2 of FIG. 3 ). Specifically, as described above, when "(torque difference) x (AYC motor rotational speed)≥0" is determined, the state is determined as the output, and the process flow goes to step S 4, and otherwise, the state is determined as the output restoration, whereby the process flow goes to step S 5.When determined as the output, as the map that calculates the torque difference distribution rate, the output distribution rate calculation map is selected (see FIG. 4B ), and the electric AYC side distribution rate is calculated depending on the charge rate of the secondary battery 19 using the map (step S 4; see the control amount distribution means B 3 of FIG. 3 ).On the other hand, when determined as the performance restoration, as the map that calculates the distribution rate of the torque difference, the distribution rate calculation map is selected upon performance restoration (see FIG. 4A ), and the distribution rate to the electric AYC side is calculated depending on the charge rate of the secondary battery 19 using the map (step S 5; see the control amount distribution means B 3 of FIG. 3 ).Next, based on the distribution rate to the electric AYC side, the electric AYC distribution amount is calculated (step S 6; see the regulation amount distributor B 3 of FIG. 3 ). The distribution amount of the electric AYC is obtained by calculation of "(torque difference) x (distribution rate)".Thereafter, the brake device distribution amount is calculated (step S 7; see the control amount distribution means B 3 of FIG. 3 ). The brake device distribution amount is obtained by calculating "(torque difference) - (electric AYC distribution amount)".In short, in steps S 3 to S 7, based on the decision result of whether the state is the power restoration or the power exercise, the map calculating the distribution amount of the torque difference is switched, the distribution rate depending on the charging rate of the secondary battery is calculated using the switched map, and the torque difference is distributed to the electric AYC side and the brake side using the calculated distribution rate.Next, the distributed torque difference, i.e., the electric-AYC distribution amount, is converted into the motor torque to be output by the AYC electric motor 15 (step S 8; see the torque difference-to-AYC electric motor torque conversion means B 4 of FIG. 3 ). The motor torque for the AYC electric motor 15 is obtained by calculating "electric AYC distribution amount) x (conversion coefficient)".Similarly, the distributed torque difference, i.e., the brake device distribution amount, is converted into the brake hydraulics that operate the brake devices 16 and 17 (step S 9; see the torque difference-to-brake hydraulic converting means B 5 of FIG. 3 ). The brake hydraulics is obtained by calculating "(brake device distribution amount) x (conversion coefficient)".Here, the vehicle wheel to be operated by the brake is determined based on the brake device distribution amount. When the torque difference is ≥ 0, the brake operation wheel is determined to be the front left wheel, and otherwise, i.e., when the torque difference is ≤ 0, the brake operation wheel is determined to be the front right wheel (steps: S 10 to S 12; see the brake operation wheel determination means B 6 of FIG. 3 ).In addition, the AYC motor 15 is controlled to output the above-mentioned motor torque (step S 13; see the AYC motor controller B 7 of FIG. 3 ).Further, the brake devices 16 and 17 are controlled to control the above-mentioned brake hydraulics with respect to the vehicle wheel determined as the operation wheel (step S 14; see the brake controller B 8 of FIG. 3 ).When the attitude control of a vehicle is performed through the above control procedure, the torque difference is distributed to the AYC motor 15 and the brake devices 16 and 17 depending on the charge rate of the secondary battery 19. Thereby, it is possible to always perform the stability control of a vehicle regardless of the charge rate of the secondary battery 19. Further, since the stability control of the vehicle is performed by using the AYC electric motor 15, the efficiency can be improved without consuming the kinetic energy of the vehicle or increasing the fuel consumption, which makes it possible to perform the control without feeling uncomfortable as a result of the deceleration.Although the invention has been specifically described and described with reference to a specific embodiment, it will be readily understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention.

Claims

A control device for controlling a left / right driving force setting device of a vehicle, the left / right driving force setting device of a vehicle comprising: a braking device (16, 17) that applies a braking force to a left wheel (13) and a right wheel (14) of a vehicle, respectively; and a motor (15) that generates a torque difference between the left wheel (13) and the right wheel (14); A secondary battery (19) capable of supplying electric power to the motor (15) and capable of charging electric power generated by the motor (15), and configured to perform stability control of a vehicle by means of the brake device (16, 17) and the motor (15), the control device comprising: calculation means that calculates a control amount that makes an actual vehicle posture follow a target vehicle posture calculated based on a vehicle state and / or an operating state; a stability control means that changes a distribution rate of the control amount to the motor (15) and the brake device (16, 17) depending on increase and decrease of a charge rate of the secondary battery (19), and controls the motor (15) and the brake device (16, 17), respectively, by the distributed control amount, thereby performing stability control of the vehicle; and a determination means that determines whether an operation of the motor (15) by the calculated control amount is a regeneration operation by the motor (15) for charging the secondary battery (19) or a driving operation by the motor (15), wherein, when it is determined by the determination means that the operation of the motor (15) is the regeneration operation, the stability control means decreases the distribution rate of the control amount to the motor (15) and increases the distribution rate of the control amount to the brake device (16, 17) in response to an increase in the charging rate of the secondary battery (19), and controls the motor (15) and the brake device (16, 17) by the distributed control amount, thereby performing stability control of the vehicle, wherein when it is determined by the determination means that the operation of the motor (15) is the driving operation, the stability control means decreases the distribution rate of the control amount to the motor (15) and increases the distribution rate of the control amount to the brake device (16, 17) in response to a decrease in a charging rate of the secondary battery (19), and controls the motor (15) and the brake device (16, 17) by the distributed control amount, whereby a stability control of the vehicle is performed.The control apparatus according to claim 1, wherein when it is determined by the determining means that the operation of the engine (15) is the regeneration operation, the stability control means controls, in a first state in which the charging rate is nearly 100%, the distribution rate to the engine (15) is set to 0% and the distribution rate to the braking device (16, 17) is set to 100%, and only the braking device (16, 17), thereby performing stability control of the vehicle, and wherein when it is determined by the determining means that the operation of the engine (15) is the driving operation, the stability control means controls, in a second state in which the charging rate is nearly 0%, the distribution rate to the engine (15) is set to 0% and the distribution rate to the braking device is set to 100%, and only the braking device (16, 17), whereby a stability control of the vehicle is performed.The control device according to claim 2, wherein a maximum charging rate in the first state is a charging rate at which the secondary battery (19) is overcharged by electricity generation of the motor (15) and is less than 100%, and wherein a minimum charging rate in the second state is a charging rate at which the charging rate becomes 0% and is greater than 0% due to electric power consumption of the motor (15).

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