JP2008278652A - Driving force controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately suppress resonance torque caused in a driving system, to prevent reduction of output torque for more than need and to suppress deterioration of driveability in a driving force controller. <P>SOLUTION: Driving torque of a motor 14 is transmitted to a wheel 18 from a driving shaft 16 through a speed reducer 15 and an output shaft 17 and a wheel 20 can be driven. Transmission torque transmitted to the speed reducer 15 and the output shaft 17 can be changed by changing a current value applied to the motor 14. ECU 23 changes the current value applied to the motor 14 by considering inertia moment operated on the motor 14. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a driving force control device for a vehicle capable of driving driving wheels with an electric motor, and more particularly to a driving force control device having an in-wheel motor.

  In recent years, vehicles such as electric vehicles, hybrid vehicles, and fuel cell vehicles that employ an AC motor as a driving source for vehicle propulsion and are equipped with a motor driving device that drives the AC motor have appeared.

  As a conventional driving force control device, there is one described in Patent Document 1 below.

  The power output device described in this patent document 1 includes an engine on a planetary carrier of a planetary gear, a motor on a sun gear, a motor and an axle on a ring gear, a clutch provided between the planetary gear and the motor, A series hybrid can be realized by providing a brake that locks the ring gear when the clutch is disengaged and connecting the clutch to realize a parallel hybrid vehicle configuration, and by disengaging the clutch and fixing the ring gear with the brake The configuration of the vehicle can be realized.

  By the way, in a vehicle that can be driven by an electric motor, when the vehicle is driven by the driving torque of the electric motor and the wheels are braked by a brake device, in particular, the electric motor is driven positively with respect to the driving shaft of the electric motor. The motor torque in the rotation direction and the brake torque in the reverse rotation direction by the brake device act, and torsion torque, that is, resonance torque acts on the drive shaft. In this case, in a vehicle having an in-wheel motor, the drive transmission system including the speed reduction mechanism from the drive shaft of the electric motor to the wheels (wheels) is short, so that it is difficult to absorb resonance torque by this drive transmission system.

  In the conventional power output apparatus described above, it is detected whether or not resonance has occurred in at least one of the output shaft and the drive shaft of the engine, and when this resonance is detected, the coupling mechanism and the holding mechanism are controlled, This resonance is suppressed by suppressing the torque of the shaft where the resonance occurs.

JP 2000-209706 A

  However, when the electric motor or the like resonates, not only the driving torque of the electric motor but also the moment of inertia acts on the output shaft. Therefore, when resonance is detected as in the conventional power output device, if the resonance is suppressed by reducing the motor torque of the electric motor based on the breaking torque of the output shaft, etc., not only the transmission torque but also the moment of inertia There is a problem that the output torque is reduced more than necessary, and the drivability is deteriorated.

  The present invention is intended to solve such a problem, and can appropriately suppress the resonance torque generated in the drive system and prevent a decrease in output torque more than necessary to suppress deterioration in drivability. It is an object of the present invention to provide a driving force control device that enables this.

  In order to solve the above-described problems and achieve the object, the driving force control apparatus of the present invention can drive the motor by transmitting the driving torque of the motor to the wheels via the driving transmission system, and apply the driving torque to the motor. In the driving force control device capable of changing the transmission torque transmitted to the drive transmission system by changing the current value, the current value applied to the motor is changed in consideration of the moment of inertia acting on the motor. It is a feature.

  In the driving force control device according to the present invention, the change is applied to the motor based on the change amount of the drive torque due to the change of the current value applied to the motor and the change amount of the moment of inertia due to the change of the current value applied to the motor. It is characterized by setting a current value.

  In the driving force control apparatus of the present invention, when the braking pressure of the brake device exceeds a preset first determination value, and the rate of change of the braking pressure of the brake device exceeds a preset second determination value The reduction amount of the current value applied to the motor is set based on the reduction amount of the driving torque due to the reduction of the current value applied to the motor and the reduction amount of the moment of inertia due to the reduction of the current value applied to the motor. It is characterized by doing.

  In the driving force control apparatus of the present invention, the resonance torque of the drive transmission system is estimated based on the driving torque of the motor, the moment of inertia acting on the motor, and the braking torque by the brake device, and the estimated resonance torque is When a preset allowable torque of the drive transmission system is exceeded, a reduction amount of the drive torque due to a decrease in the current value applied to the motor, and a reduction amount of the moment of inertia due to a decrease in the current value applied to the motor, The reduction amount of the current value applied to the motor is set based on the above.

  The driving force control apparatus of the present invention is characterized in that when the resonance torque exceeds the allowable torque, a reduction amount of the current value applied to the motor is set according to a deviation between the resonance torque and the allowable torque.

  According to the driving force control apparatus of the present invention, the driving torque of the motor can be transmitted to the wheels via the driving transmission system and can be driven, and the current applied to the motor is changed and transmitted to the driving transmission system. The transmission torque can be changed, and the current value applied to the motor is changed in consideration of the moment of inertia acting on the motor, so that the resonance torque generated in the drive transmission system can be appropriately suppressed, It is possible to prevent the output torque from being reduced more than necessary and suppress the deterioration of drivability.

  Embodiments of a driving force control apparatus according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this Example.

  FIG. 1 is a schematic configuration diagram illustrating a driving force control apparatus according to an embodiment of the present invention, FIG. 2 is a flowchart illustrating resonance suppression control by the driving force control apparatus of the present embodiment, and FIG. FIG. 3-2 is a graph showing the change of the resonance torque with respect to the moment of inertia, FIG. 3-3 is a graph showing the change of the resonance torque with respect to the brake torque, and FIG. FIG. 4B is a graph showing a change in the resonance torque with respect to the moment of inertia, FIG. 5A is a graph showing a change in the motor torque with respect to the motor current value, and FIG. Is a graph showing the change of the resonance torque with respect to the motor torque, and FIG. 6 is a graph showing the motor torque and the resonance torque when the resonance suppression control is performed by the driving force control apparatus of this embodiment. Is a time chart showing the change of the clause.

  The driving force control apparatus of this embodiment is a vehicle driving apparatus to which an in-wheel motor is applied. As shown in FIG. 1, the knuckle arm 11 is an upper arm (not shown) whose upper end is supported on the vehicle body side. While being connected via a ball joint, the lower end is connected via a ball joint to a lower arm 12 supported on the vehicle body side. Further, a shock absorber and a coil spring (not shown) are interposed between the vehicle body side and the lower arm 12.

  A housing 13 is fixed to the knuckle arm 11, and a motor 14 and a speed reducer 15 are accommodated in the housing 13. That is, the motor 14 includes a stator core that is fixed to the housing 13 and has a ring shape, a rotor that is rotatably supported inside the stator core with a predetermined gap, and a drive shaft 16 that is fixed to the rotor. Has been. On the other hand, the speed reducer 15 is a speed reducer composed of, for example, a planetary gear mechanism, and decelerates the rotation (drive torque) of the drive shaft 16 of the motor 14 and transmits it to the output shaft 17 (transfer torque).

  On the other hand, the wheel 18 has a cylindrical shape, a tire 19 is mounted on the outer peripheral side to form a wheel 20, and the output shaft 17 of the speed reducer 15 is connected. A brake disc 21 is connected to the output shaft 17, and the brake disc 21 can be locked by a brake caliper 22 mounted on the vehicle body side.

  The vehicle is equipped with an electronic control unit (ECU) 23, which includes an accelerator opening sensor 25 that detects the accelerator opening of the accelerator pedal 24 and a pedal stroke (or a brake pedal 26). A stroke sensor (a pedaling force sensor) 27 for detecting a pedaling force) is connected. The ECU 23 is connected to a master cylinder pressure sensor 30 that detects the master cylinder pressure of the wheel cylinder 29 in the brake device 28 that operates the brake caliper 22.

  Accordingly, the ECU 23 estimates the driver's required driving force from the accelerator opening detected by the accelerator opening sensor 25, sets a motor current value to be supplied to the motor 14 based on this required driving force, Drive control. That is, when a predetermined motor current value is supplied to the motor 14, the drive shaft 16 is rotated together with the rotor with respect to the stator core, the rotation of the drive shaft 16 is decelerated by the speed reducer 15, and the output shaft 17 is rotated. The wheel 18 connected to the shaft 17 rotates, and the wheel 20 can be driven to rotate.

  Further, the ECU 23 estimates the driver's required braking force from the brake stroke detected by the stroke sensor 27, and sets the master cylinder pressure to be supplied from the brake device 28 to the wheel cylinder 29 based on the required braking force. The cylinder 29 is controlled. That is, when a predetermined master cylinder pressure is supplied to the wheel cylinder 29, the brake caliper 22 is actuated by the wheel cylinder 29 to lock the brake disc 21, and a braking force is applied to the wheel 18 connected to the brake disc 21. The rotation of the wheel 20 can be stopped.

  By the way, in the vehicle described above, when the wheel 20 is braked by the brake device 28 during traveling by the driving torque of the motor 14, the forward rotation direction by the motor 14 with respect to the drive transmission system from the motor 14 to the output shaft 17. Motor torque and brake torque in the reverse rotation direction by the brake device 28 act, and torsion torque, that is, resonance torque acts on this drive transmission system. At this time, it is possible to suppress the resonance torque by reducing the current value of the motor 14 and lowering the drive torque, but this drive transmission system includes not only the drive torque of the motor 14 but also the moment of inertia. It is working. Therefore, when the current value of the motor 14 is reduced according to the generated resonance torque, not only the drive torque but also the moment of inertia is reduced, and the output torque is reduced more than necessary.

  Therefore, in the driving force control apparatus according to the present embodiment, when the vehicle is running with the wheels 20 driven by the motor 14, when the driver depresses the brake pedal 26 and performs a braking operation, the ECU 23 transmits the drive transmission of the motor 14. The value of current applied to the motor 14 is changed in consideration of the moment of inertia acting on the system. Specifically, the current value to be applied to the motor 14 is set based on the change amount of the drive torque due to the change of the current value applied to the motor 14 and the change amount of the moment of inertia due to the change of the current value applied to the motor 14. is doing.

  Here, the resonance suppression control by the driving force control apparatus of the present embodiment will be described in detail with reference to the flowchart of FIG.

  In the resonance suppression control by the driving force control device of the present embodiment, as shown in FIG. 2, in step S1, the ECU 23 determines that the master cylinder pressure (braking pressure) P detected by the master cylinder pressure sensor 30 in the brake device is It is determined whether or not a first determination value α set in advance is exceeded. Here, if it is determined that the master cylinder pressure P has exceeded the first determination value α, in step S2, the master cylinder pressure increase amount per unit time (change amount of the braking pressure), that is, the master cylinder pressure increase rate ( It is determined whether or not the braking pressure change rate dP has exceeded a preset second determination value β. Here, if it is determined that the master cylinder pressure increase rate dP exceeds the second determination value β, the ECU 23 estimates that the driver suddenly applied the brake.

  When the driver suddenly brakes, it is estimated that resonance torque is generated in the drive transmission system of the motor 14, and therefore, in step S3, the resonance torque Tr generated in the drive transmission system is estimated. Here, it can be seen that the resonance torque generated in the drive transmission system is assumed to change according to the motor torque of the motor 14, the moment of inertia of the motor 14, and the brake torque of the brake device 28. That is, as shown in FIG. 3-1, the resonance torque Tr increases as the motor torque Tm increases, and as shown in FIG. 3-2, the resonance torque Tr increases as the inertia moment Jm increases. As shown in FIG. 3C, the resonance torque Tr increases as the brake torque Tb increases.

  Therefore, the ECU 23 estimates the resonance torque Tr based on the motor torque Tm, the moment of inertia Jm, and the brake torque Tb. In this embodiment, the ECU 23 estimates the driver's required driving force from the accelerator opening detected by the accelerator opening sensor 25, and estimates the driver's required braking force from the brake stroke detected by the stroke sensor 27. The motor torque Tm and the moment of inertia Jm can be calculated from the required driving force, and the brake torque Tb can be calculated from the required braking force. Then, the resonance torque Tr is calculated based on the calculated motor torque Tm, moment of inertia Jm, and brake torque Tb. In this case, the resonance torque Tr can be easily obtained in a short time by using a map representing the relationship among the motor torque Tm, the moment of inertia Jm, the brake torque Tb, and the resonance torque Tr.

  Subsequently, in step S4, it is determined whether or not the estimated resonance torque Tr exceeds a preset allowable torque Ta of the drive transmission system. In this case, the allowable torque Ta of the drive transmission system is a breaking torque of the drive shaft 16 of the motor 14, the speed reducer 15, the output shaft 17, and the like. Here, if it is determined that the resonance torque Tr has exceeded the allowable torque Ta, in step S5, the amount of reduction in the output torque due to the decrease in the current value applied to the motor 14 and the inertia due to the decrease in the current value applied to the motor 14 are determined. A reduction amount of the current value applied to the motor 14 is set based on the reduction amount of the moment.

That is, when the resonance torque Tr exceeds the allowable torque Ta, the resonance reduction torque ΔT necessary for reducing the resonance torque is obtained according to the deviation between the resonance torque Tr and the allowable torque Ta.
Tr-Ta = ΔT
The resonance reduction torque ΔT is a resonance reduction torque ΔT1 corresponding to a reduction in moment of inertia due to a decrease in the current value applied to the motor 14, and a resonance corresponding to a reduction in drive torque due to a reduction in the current value applied to the motor 14. The torque is distributed to the reduced torque ΔT2.
ΔT = ΔT1 + ΔT2
The resonance reduction torque ΔT1 corresponding to the reduction of the inertia moment and the resonance reduction torque ΔT2 corresponding to the reduction of the driving torque can be determined from the torque change amount per unit time.

  As shown in FIG. 4A, when the motor current value Im is decreased by a predetermined amount ΔIm, the moment of inertia Jm is decreased by a predetermined amount ΔJm. As shown in FIG. 4B, when the inertia moment Jm is reduced by a predetermined amount ΔJm, the resonance torque Tr is reduced by the resonance reduction torque ΔT1 corresponding to the reduction of the inertia moment.

  On the other hand, as shown in FIG. 5A, when the motor current value Im is decreased by a predetermined amount ΔIm, the motor torque Tm is decreased by a predetermined amount ΔTm. As shown in FIG. 5B, when the motor torque Tm decreases by a predetermined amount ΔTm, the resonance torque Tr decreases by the resonance reduction torque ΔT2 corresponding to the reduction of the drive torque.

  Accordingly, the resonance reduction torque ΔT is obtained according to the deviation between the estimated resonance torque Tr and the allowable torque Tr, and the resonance reduction torque ΔT is determined according to the resonance reduction torque ΔT1 according to the reduction of the moment of inertia and the drive torque reduction. Based on the relationship between the resonance reduction torque ΔT1, the moment of inertia Jm, and the motor current value Im, and the relationship between the resonance reduction torque ΔT2, the motor torque Tm, and the motor current value Im, after being distributed to the resonance reduction torque ΔT2. A reduction amount ΔIm of the current value Im can be set. Then, the current value Imr for suppressing the resonance torque is calculated by adding the reduction amount ΔIm of the obtained motor current value Im to the current value Im applied to the motor 14 when the driver suddenly brakes. .

  In step S1 described above, it is determined that the master cylinder pressure P detected by the master cylinder pressure sensor 30 does not exceed the first determination value α, or in step S2, the master cylinder pressure increase rate dP is a second value. If it is determined that it does not exceed the determination value β, or if it is determined in step S4 that the estimated resonance torque Tr does not exceed the allowable torque Ta of the drive transmission system, this routine is exited without doing anything.

  Here, the effect | action by the resonance suppression control by the driving force control apparatus of a present Example is demonstrated in detail based on a time chart in FIG.

  As shown in FIG. 6, when the driver suddenly brakes at time t1, resonance torque Tr is generated at this time. Therefore, the moment of inertia is reduced by the decrease in the current value applied to the motor 14 over time t2. The current value of the motor 14 is reduced in consideration of a reduction in driving torque due to a decrease in the current value applied to the motor 14. Then, by reducing the current value of the motor 14, the generation of the resonance torque Tr is suppressed, and the resonance torque Tr converges at time t3. Then, although the motor torque Tm decreases as the current value of the motor 14 decreases, a significant decrease in the motor torque Tm can be prevented as in the conventional case shown by the one-dot chain line in FIG.

  As described above, in the driving force control apparatus according to the present embodiment, the driving torque of the motor 14 can be transmitted from the driving shaft 16 to the wheel 18 via the speed reducer 15 and the output shaft 17 to drive the wheel 20. The transmission torque transmitted to the speed reducer 15 and the output shaft 17 can be changed by changing the value of the current applied to the motor 14, and the ECU 23 considers the moment of inertia acting on the motor 14 and The current value applied to 14 is changed.

  Therefore, even when a resonance torque is generated in the drive transmission system composed of the drive shaft 16, the speed reducer 15, and the output shaft 17 of the motor 14 when the driver suddenly brakes, the inertia that the ECU 23 acts on the motor 14. By changing the current value in consideration of the moment, the generated resonance torque can be properly suppressed, and the output torque can be prevented from being reduced more than necessary, and as a result, deterioration of drivability can be suppressed. it can.

  In the driving force control apparatus according to the present embodiment, the motor torque is reduced by changing the current value applied to the motor 14 and the motor inertia is reduced by changing the current value applied to the motor 14. The current value to be applied to 14 is set. Therefore, in consideration of the moment of inertia acting on the motor 14, the current value of the motor 14 necessary for suppressing the resonance torque can be set appropriately.

  Further, in the driving force control apparatus of the present embodiment, the master cylinder pressure of the brake device 28 exceeds the preset first determination value, and the change rate of the master cylinder pressure of the brake device 28 exceeds the second determination value. The current value is changed in consideration of the moment of inertia acting on the motor 14. Therefore, the driver can detect sudden braking reliably and appropriately suppress the resonance torque generated in the drive shaft 16, the speed reducer 15, and the output shaft 17 of the motor 14.

  In the driving force control apparatus of this embodiment, the resonance torque of the drive transmission system is estimated based on the motor torque, the moment of inertia, and the brake torque, and when the estimated resonance torque exceeds the allowable torque of the drive transmission system. The current value is changed in consideration of the moment of inertia acting on the motor 14. In this case, when the resonance torque exceeds the allowable torque, a reduction amount of the current value applied to the motor 14 is set according to the deviation between the resonance torque and the allowable torque. Therefore, the resonance torque of the drive transmission system can be estimated with high accuracy, and the generated resonance torque can be appropriately suppressed.

  In the above-described embodiments, the driving force control device of the present invention is described as applied to a vehicle using an in-wheel motor. However, an electric motor may be applied to a vehicle or a hybrid vehicle.

  In the above-described embodiment, the driver's required driving force is estimated from the accelerator opening detected by the accelerator opening sensor 25, and the driver's required braking force is estimated from the brake stroke detected by the stroke sensor 27. The motor torque Tm and the moment of inertia Jm are calculated from the required driving force, and the brake torque Tb is calculated from the required braking force. However, various sensors are arranged to calculate the motor torque Tm, the inertia moment Jm, and the brake torque Tb. It may be detected directly.

  As described above, the driving force control apparatus according to the present invention appropriately suppresses the resonance torque generated in the drive system by changing the current value in consideration of the moment of inertia acting on the motor, and outputs more than necessary. This is to prevent torque reduction and is useful for any vehicle.

It is a schematic block diagram showing the driving force control apparatus which concerns on one Example of this invention. It is a flowchart showing the resonance suppression control by the driving force control apparatus of a present Example. It is a graph showing the change of the resonant torque with respect to a motor torque. It is a graph showing the change of the resonant torque with respect to an inertia moment. It is a graph showing the change of the resonant torque with respect to a brake torque. It is a graph showing the change of the moment of inertia with respect to a motor current value. It is a graph showing the change of the resonant torque with respect to an inertia moment. It is a graph showing the change of the motor torque with respect to a motor current value. It is a graph showing the change of the resonant torque with respect to a motor torque. It is a time chart showing the change of a motor torque and resonance torque when resonance suppression control by the driving force control apparatus of a present Example is implemented.

Explanation of symbols

DESCRIPTION OF SYMBOLS 14 Motor 15 Reducer 16 Drive shaft 17 Output shaft 18 Wheel 20 Wheel 23 Electronic control unit (ECU)
28 Brake device 30 Master cylinder pressure sensor

Claims (5)

  A driving force capable of transmitting the driving torque of the motor to the wheels via the driving transmission system and changing the transmission torque transmitted to the driving transmission system by changing the current value applied to the motor. In the control device, the current value applied to the motor is changed in consideration of the moment of inertia acting on the motor.   2. The driving force control apparatus according to claim 1, wherein the motor is based on a change amount of a drive torque due to a change in a current value applied to the motor and a change amount of an inertia moment due to a change in the current value applied to the motor. A driving force control apparatus characterized by setting a current value applied to the.   The driving force control device according to claim 1 or 2, wherein the braking pressure of the brake device exceeds a preset first judgment value, and the rate of change of the braking pressure of the brake device is preset. A current value applied to the motor based on a reduction amount of the drive torque due to a decrease in the current value applied to the motor and a reduction amount of the moment of inertia due to a decrease in the current value applied to the motor when the value exceeds A driving force control apparatus characterized by setting a reduction amount of the driving force.   The driving force control device according to any one of claims 1 to 3, wherein a resonance torque of the drive transmission system based on a driving torque of the motor, an inertia moment acting on the motor, and a braking torque by the braking device. And when the estimated resonance torque exceeds a preset allowable torque of the drive transmission system, the amount of reduction in drive torque due to a decrease in the current value applied to the motor and the current applied to the motor A driving force control device, wherein a reduction amount of a current value applied to the motor is set based on a reduction amount of the moment of inertia due to a decrease in value.   5. The driving force control apparatus according to claim 4, wherein when the resonance torque exceeds the allowable torque, a reduction amount of the current value applied to the motor is set according to a deviation between the resonance torque and the allowable torque. A driving force control device.

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