JP4453653B2 - Torque distribution control device for hybrid vehicle - Google Patents

Description

  The present invention belongs to the technical field of a torque distribution control device for a hybrid vehicle that has an engine and a motor as drive sources and controls at least one of front and rear wheel torque distribution and left and right wheel torque distribution using the output torque of the motor. .

(Prior art 1)
Conventionally, an engine, a first motor that is mechanically coupled to the engine and the front wheels and electrically coupled to the battery, and mechanically coupled to the rear wheels and electrically coupled to the battery A hybrid vehicle including a second motor is known (see, for example, Patent Document 1).

(Prior art 2)
On the other hand, mechanical four-wheel drive vehicles that realize neutral steer by controlling the front-rear distribution at 30:70 to 70:30 and the rear wheel left-right distribution at 100: 0 to 0: 100 are known (for example, Patent Document 2).
JP 2004-222413 A JP 2004-189067 A

However, when the technical concept of torque distribution of the above-described conventional technique 2 is applied to the hybrid vehicle of the above-described conventional technique 1, the following problems occur.
That is, when controlling torque distribution to the left and right rear wheels using the output torque of the second motor so as to achieve neutral steering during turning, torque distribution control to the left and right rear wheels (large turning outer ring torque, turning inner ring torque) When a fault is detected in the high-voltage system electrically coupled to the second motor during the turning of the small motor, the system immediately shuts off energy transfer with the high-voltage battery in synchronization with the fault detection timing. The main relay (hereinafter abbreviated as “SMR”) is turned OFF, and the output torque of the second motor is set to zero. In this case, the steer characteristic changes from neutral steer (4WD, achieved by large turning outer wheel torque on the rear wheel) to understeer (front wheel drive state) due to sudden motor torque loss at the left and right rear wheels. There was a problem that there was a possibility that the swivel behavior that was performed might be spoiled.

  The present invention has been made paying attention to the above problem, and maintains stable vehicle behavior when the motor system is off even when a failure of the high voltage system is detected during execution of torque distribution control using the output torque of the motor. An object of the present invention is to provide a torque distribution control device for a hybrid vehicle.

In order to achieve the above object, in the present invention,
It has an engine and a motor as drive sources,
A high-voltage system electrically coupled to the motor;
Torque distribution control means for controlling at least one of front and rear wheel torque distribution and left and right wheel torque distribution using the output torque of the motor;
In a torque distribution control device for a hybrid vehicle equipped with
Providing a strong electric system failure detection means for detecting that a failure that requires prohibiting energization and charging / discharging of the strong electric system occurs;
The torque distribution control means does not limit the output torque of the motor until a torque distribution difference becomes a specified value or less when it is necessary to prohibit energization or charge / discharge due to failure detection of the high-power system. And

Therefore, in the torque distribution control device for a hybrid vehicle according to the present invention, when it is necessary to prohibit energization or charging / discharging due to the failure detection of the high power system, the torque distribution control means causes the torque distribution difference to be less than the specified value. The output torque of the motor (controlling at least one of the front and rear wheel torque distribution and the left and right wheel torque distribution using the output torque) is not limited.
In other words, when a failure is detected in a high-voltage system, the motor output torque is maintained until the torque distribution difference becomes less than the specified value, instead of taking measures to prohibit energization or charging / discharging immediately in synchronization with the failure detection timing. Then, stop of the torque distribution control for controlling at least one of the front and rear wheel torque distribution and the left and right wheel torque distribution using the output torque of the motor is awaited.
For example, when performing torque distribution control to the left and right rear wheels using the output torque of the motor so as to obtain neutral steering during turning, even if a fault occurs in the high-power system, the left and right rear wheels The output torque of the motor is maintained as it is until the torque distribution difference becomes a specified value or less. And when the difference between the left and right rear wheel torque distribution becomes less than the specified value, smooth fade-out of the left and right rear wheel torque distribution control is realized such that the output torque from the motor is pulled to zero level by turning off the motor system. As a result, sudden changes in the turning behavior can be suppressed.
As a result, during the execution of torque distribution control using the output torque of the motor, even if a failure of the high power system is detected, a stable vehicle behavior can be maintained when the motor system is off.

  Hereinafter, the best mode for carrying out the torque distribution control device for a hybrid vehicle of the present invention will be described based on Example 1 and Example 2 shown in the drawings.

First, the configuration will be described.
FIG. 1 is an overall system diagram showing a hybrid four-wheel drive vehicle (an example of a hybrid vehicle) to which the torque distribution control device of the first embodiment is applied.
As shown in FIG. 1, the hybrid four-wheel drive vehicle of Embodiment 1 includes a CPU 101, an auxiliary battery 102, a high-power battery 301, an FR inverter 302, a first motor 303 (first motor), and a generator. 304, engine 305, power split mechanism 306, RR inverter 307, second motor 308 (second motor), third motor 309 (third motor), accelerator sensor 401, brake sensor 402, DC / DC converter 403, rudder angle sensor 404, GPS 405, and wheel speed sensor 406 are provided. The second motor 308 and the third motor 309 that drive the left and right rear wheels independently form a left and right wheel torque distribution mechanism.

The CPU 101 monitors the high-power battery 301, calculates the input / output possible electric energy according to the SOC, temperature, and deterioration state, and controls the FR inverter 302 based on this, thereby the first motor 303 (front drive) And the generator 304 are operated, and the engine 305 is controlled. In addition, by controlling the RR inverter 307, the second motor 308 (for the right rear drive) and the third motor 309 (for the left rear drive) are operated to achieve a four-wheel drive state, thereby realizing neutral steer. Torque distribution control for the left and right rear wheels.
In addition, the temperature sensor value built in each of the inverter 302 for FR, the first motor 303, the generator 304, the inverter 307 for RR, the second motor 308, and the third motor 309 is grasped to increase the temperature. If confirmed, protect the parts by setting power input / output limits.
Based on the detection value from the rudder angle sensor 404, it is determined whether or not the hybrid four-wheel drive vehicle is turning.
The GPS405 is used to collect terrain information and grasp the travel route.
The detection value from the wheel speed sensor 406 is confirmed to grasp each wheel speed.

  The auxiliary battery 102 serves to provide an operating power source for the CPU 101. In this system, power is supplied by a DC / DC converter 403 that uses a high-power battery 301 as a power source.

The high-power battery 301 assists the traveling of the hybrid vehicle by supplying electric power to the first motor 303 via the FR inverter 302, and uses the electric power generated by the generator 304 via the RR inverter 307. And has a role to collect.
In addition, when the second motor 308 and the third motor 309 are powered, the hybrid vehicle travel is assisted by supplying electric power via the RR inverter 307, and the second motor 308 and the third motor 309 generate power. In this case, it also has a role of collecting power via the RR inverter 307.
The proposed system also incorporates an SMR (system main relay) that is used when turning on / off a strong electric wire that supplies (transfers) power to the motor system, and this is controlled by the CPU 101.

The FR inverter 302 is directly controlled by the CPU 101. The electric energy of the high-power battery 301 is supplied to the first motor 303 according to the generated torque and the rotational speed of the engine 305, and the electric energy generated by operating the generator 304 is returned to the high-power battery 301. The first motor 303, the generator 304, and the engine 305 are directly connected to the planetary gear mechanism (incorporated in the power split mechanism 306). Cannot be activated.
In addition, a temperature sensor is incorporated so that power input / output restriction (component protection) can be performed when the temperature rises, and the detection value is transmitted to the CPU 101.

The first motor 303 is for front drive and generates drive torque independently when the vehicle speed is low. Further, when the vehicle speed is high, the driving torque of the engine 305 is assisted. Further, when decelerating, it has a function of generating electric energy by generating power (regenerative action) and returning it to the high-voltage battery 301 via the FR inverter 302. Further, the control is applied with the motor rotation speed = vehicle speed.
In addition, a temperature sensor is built in so that power input / output restriction (part protection) can be performed when the temperature rises, and a detection value is transmitted to the CPU 101.

The generator 304 basically has no starter in a hybrid electric vehicle. When the hybrid vehicle to which this system is applied is started, the electric power is supplied from the high-power battery 301, and the engine 305 is started by operating as a motor. During normal travel, electric energy is generated (power generation) by balancing the first motor 303 and the engine 305 and is returned to the high-power battery 301. Sometimes, it is possible to cope with rapid acceleration by supplying the first motor 303 directly.
In addition, a temperature sensor is incorporated so that power input / output restriction (component protection) can be performed when the temperature rises, and the detection value is transmitted to the CPU 101.

  The engine 305 is directly controlled by the CPU 101. Specifically, when the vehicle speed is high, torque is generated to drive the hybrid vehicle.

  The power split mechanism 306 has a planetary gear mechanism, and an engine 305 is directly connected to the carrier, a first motor 303 is connected to the ring gear, and a generator 304 is directly connected to the sun gear. The transmission equivalent of the conventional system is also configured inside.

The RR inverter 307 is directly controlled by the CPU 101. It plays a role of supplying / recovering the electric energy of the high-power battery 301 in accordance with the torque generated and the rotational speed of the second motor 308 and the third motor 309.
In addition, a temperature sensor is incorporated so that power input / output restriction (component protection) can be performed when the temperature rises, and the detection value is transmitted to the CPU 101.

The second motor 308 is in charge of right rear driving as a 4WD hybrid vehicle during normal traveling, and generates torque in the travel course increase caused by the inner wheel difference during turning, contributing to improved traveling and steering stability. .
In addition, a temperature sensor is incorporated so that power input / output restriction (component protection) can be performed when the temperature rises, and the detection value is transmitted to the CPU 101.

The third motor 309 is responsible for driving the left rear as a 4WD hybrid vehicle during normal running, and during turning, torque is generated due to the increase in the running course caused by the inner wheel difference, contributing to improved running and steering stability. .
In addition, a temperature sensor is incorporated so that power input / output restriction (component protection) can be performed when the temperature rises, and the detection value is transmitted to the CPU 101.

  The accelerator sensor 401 transmits to the CPU 101 the amount of accelerator pedal stroke that the driver has depressed during acceleration.

  The brake sensor 402 transmits to the CPU 101 the brake pedal stroke amount that the driver has depressed when decelerating.

  The DC / DC converter 403 converts the energy from the high voltage battery 301 into 12V and supplies it to the auxiliary battery 102. That is, it has the same function as an alternator in a conventional engine hybrid vehicle.

  The steering angle sensor 404 has a function of transmitting a steering angle detected by a driver's steering operation to the CPU 101.

  The GPS (Global Positioning System) 405 extracts the corner turning radius, the gradient, and the estimated road surface μ that exist up to the destination, and presents each information to the CPU 101.

  The wheel speed sensor 406 is connected to the front two wheels, and transmits the detected value to the CPU 101 as wheel speed information.

  FIG. 2 is a flowchart showing the flow of torque distribution control processing executed by the CPU 101 of the first embodiment, and each step will be described below (torque distribution control means).

In step S1, it is determined whether or not a high-power system that requires the energy of the high-power battery 301 to be disconnected from the vehicle system is detected. If Yes, the process proceeds to step S2. If No, the determination in step S1 is performed. Is repeated (strong electric system failure detection means).
Here, specific target units of the high-power system are a high-power battery 301, an FR inverter 302, a first motor 303, a generator 304, an RR inverter 307, a second motor 308, and a third motor 309. However, not all failures are applicable, and failures that require energization and charging / discharging are targeted.

In step S2, it is determined whether or not the own vehicle is turning following the determination that the high-voltage system requiring SMR OFF occurs in step S1, and if yes, the process proceeds to step S3. In this case, the process proceeds to step S4 (own vehicle turning determination means).
Here, “determination during turning of the host vehicle” determines that the vehicle is turning when the detection value (absolute value) from the rudder angle sensor 404 is equal to or greater than a specified value. Alternatively, it is determined whether or not the vehicle is turning by checking whether or not the turning performance improvement control is applied to the second motor 308 and the third motor 309.
During turning, the second motor 308 and the third motor 309 are utilized to improve the turning performance, so that it is considered that electric energy transfer cannot be interrupted in order to ensure vehicle behavior.

In step S3, following the determination that the host vehicle is turning in step S2, it is determined whether or not the vehicle speed and the torque distribution difference have no problem even if the torque distribution control to the left and right rear wheels is discontinued during the turn. If Yes, the process proceeds to step S4. If No, the determination in step S3 is repeated.
This step S3 is basically a determination not to limit the output torque of the second motor 308 and the third motor 309 until the torque distribution difference between the left and right rear wheels becomes equal to or less than a specified value. The prescribed value of the torque distribution difference between the left and right rear wheels that delays the limit of the output torque of the second motor 308 and the third motor 309 is a value that can ensure the stability of the vehicle behavior even if the torque distribution control of the left and right rear wheels is stopped. Set to
Specifically, using a turning torque distribution control abortion determination map (control cancellation availability determination map) in which a region where the absolute value of the left and right wheel torque distribution difference is smaller as the host vehicle speed is higher is shown in FIG. If it is determined that the operating point of the vehicle (the vehicle speed, the absolute value of the left and right wheel torque distribution difference) has entered the turning torque distribution control termination region on the map, the process proceeds to step S4, SMR is turned off, and the left and right rear Discontinue wheel torque distribution control.

In step S4, when it is determined in step S2 that the vehicle is not turning, or when it is determined that there is a vehicle speed and torque distribution difference that does not matter even if the torque distribution control to the left and right rear wheels is discontinued during the turn, The SMR set in the high-power battery 301 is turned off, the energy of the high-power battery 301 is disconnected from the vehicle system, and the process proceeds to step S5.
That is, when it becomes necessary to prohibit energization or charging / discharging due to the failure detection of the high power system, if it is determined that the vehicle is not turning, the SMR is immediately turned off and the vehicle is determined to be turning. In this case, the SMR is turned off after waiting for the judgment to stop the torque distribution control of the left and right rear wheels.

In step S5, after the SMR in step S4d is turned off and the high-power battery 301 cannot be used after the SMR is turned off, the battery-less travel mode is set in which the high-power battery 301 is not used as a fail safe. The process proceeds to step S6.
Here, the “battery-less travel mode” refers to a travel mode in which a driving force that causes the vehicle to travel with only the engine 305 is generated.

  In step S6, following the transition to the battery-less travel mode in step S5, a warning (flashing warning light, warning, etc.) is given to inform the occupant that the high power system is out of order, and the process proceeds to step S7.

  In step S7, following the failure warning of the high-power system in step S6, it is determined whether or not the high-power battery 301 is in the high-power battery failure mode as a failure mode of the high-power system. If No (the failure mode of the inverter or the like), the process returns to step S5.

In step S8, following the determination in step S7 that the battery is in the high-power battery failure mode, it is determined whether or not the vehicle is turning. If yes, the process proceeds to step S9. If no, step S5 is performed. Return to.
Here, “determination during turning of the host vehicle” determines that the vehicle is turning when the detection value (absolute value) from the rudder angle sensor 404 is equal to or greater than a specified value.

  In step S9, following the determination that the vehicle is turning in step S8, of the second motor 308 and the third motor 309 that individually drive the left and right rear wheels, the motor on the turning inner ring side is regenerated, turning outer wheel The motor on the side is set to power running, and control is performed to cover the driving energy of the power running motor with the power generated by the regenerative motor, and the process returns to step S5. Note that the torque distribution control process is completed by turning off the ignition switch.

Next, the operation will be described.
[Background technology]
For example, as shown in FIG. 1, a hybrid four-wheel drive vehicle is configured, and torque distribution to the left and right rear wheels is performed using the output torque of the second motor 308 and the third motor 309 so as to realize neutral steering during turning. When controlling, a strong electric system that is electrically coupled to the second motor 308 and the third motor 309 during a turn in which torque distribution control (large turning outer ring torque, small turning inner ring torque) is being executed. When a system failure is detected, energy transfer with the high-power battery 301 is immediately cut off in synchronization with the failure detection timing, so that the SMR set in the high-power battery 301 is turned OFF, and the second motor 308 and the third motor 309 are turned off. The output torque is set to zero.
In this case, the steer characteristic changes from neutral steer (4WD, achieved by large turning outer wheel torque at the rear wheel) to understeer (front wheel drive state) due to a sudden motor torque loss at the left and right rear wheels. There is a risk that the swivel behavior will be impaired.

By the way, the relationship between the steering characteristics of the vehicle and the torque distribution shows that in the case of front and rear wheel torque distribution, the front wheel drive vehicle with 100% torque distribution shows the most understeer tendency and the rear wheel torque distribution is 100%. In the case of% rear-wheel drive vehicles, it shows the most oversteer tendency. In addition, in the case of torque distribution of the left and right rear wheels, the torque distribution to the turning outer wheel becomes larger when the torque distribution to the turning inner wheel is larger than the torque distribution to the turning inner wheel, and conversely, the torque distribution to the turning inner wheel is larger than the torque distribution to the turning outer wheel. The understeer side.
In the hybrid four-wheel drive vehicle of the present application, when the torque distribution to the left and right rear wheels is equally distributed, the front wheel drive state or the four-wheel drive state is set to show an understeer tendency, and the torque distribution to the left and right rear wheels is set to the turning outer wheel. By making the torque distribution to the vehicle larger than the torque distribution to the turning inner wheel, a neutral steer that achieves turning ability in accordance with the turning intention that appears in the steering operation of the driver is realized.

[Torque distribution control function]
On the other hand, in the hybrid vehicle torque distribution control apparatus according to the first embodiment, when a failure occurs in the high-voltage system, the SMR is not turned off and the energy is supplied to the motor until the torque distribution difference becomes a specified value or less. By continuing, even if a fault in the high-power system is detected during execution of torque distribution control using the output torque of the motor, stable vehicle behavior can be maintained when the motor system is off.

First, when a failure occurs in the high power system during straight traveling, the process proceeds from step S1 to step S2 to step S4 to step S5 in the flowchart of FIG. In step S4, based on the determination that the vehicle is not turning in step S2, the SMR set in the high-power battery 301 is turned off. In step S5, only the engine 305 is used without using the high-power battery 301. The transition to the “battery-less travel mode” in which the driving force for traveling the vehicle is generated.
Therefore, when a failure occurs in the high-voltage system during straight running with almost no effect on the vehicle behavior even when the SMR is turned off, the high-power system is improved in response by turning off the SMR immediately when a failure occurs in the high-voltage system. Can be protected. In other words, when a failure occurs in the high-power system during straight running, control is performed with priority on protection of the high-power system.

  On the other hand, if a failure occurs in the high-voltage system during turning, the process proceeds from step S1 to step S2 to step S3 in the flowchart of FIG. 2. In step S3, torque distribution control to the left and right rear wheels is performed during turning. The determination as to whether the vehicle speed and the torque distribution difference have no problem even if it is terminated is repeated. That is, even if a failure occurs in the high-power system, the torque distribution control for the left and right rear wheels while turning is maintained with the SMR turned on.

If it is determined in step S3 that the vehicle speed and the torque distribution difference have no problem even if the torque distribution control to the left and right rear wheels is discontinued during turning, the process proceeds from step S3 to step S4 to step S5 in the flowchart of FIG. In step S4, based on the determination that the vehicle is not turning in step S2, the SMR set in the high-power battery 301 is turned off. In step S5, the high-power battery 301 is not used and the engine 305 is not used. Transition to the “battery-less running mode” in which the driving force for running the vehicle is generated alone.
That is, when a failure is detected in the high-voltage system, measures are not taken immediately to prohibit energization or charging / discharging in synchronization with the failure detection timing, but until the torque distribution difference between the left and right rear wheels becomes less than the specified value. The output torque of the motor 308 and the third motor 309 is maintained, and the stop of the torque distribution control of the left and right rear wheels using the output torque of the second motor 308 and the third motor 309 is awaited.

For example, FIG. 4 shows a system failure occurrence, a steering angle sensor detection value (absolute value), a motor rotation speed (= vehicle speed), and a second motor required torque when a failure occurs in the high-voltage system in the torque distribution control of the first embodiment. -It is a time chart which shows each characteristic of 3rd motor request | requirement torque and SMR.
At time t1, simultaneously with the start of the left turn, the torque distribution control of the left and right rear wheels to obtain neutral steer is performed by gradually increasing the required torque for the second motor 308 and gradually decreasing the required torque for the third motor 309. Be started. At time t2, even if a failure occurs in the high-power system, time t3 when the steering angle reaches a peak elapses, and the operating point of the vehicle based on the vehicle speed and the absolute value of the left and right wheel torque distribution difference is shown in FIG. The output torques of the second motor 308 and the third motor 309 are maintained as they are until the time t4 when entering the region where control can be aborted in the turning torque distribution control abortability determination map shown in FIG. Then, by turning off the SMR at the time t4, the actual output torque (dotted line characteristics) from the second motor 308 and the third motor 309 is extracted to the zero level. Since this situation can be handled in a few seconds at the longest, the load on the high-voltage system is small, and the impact on the service life is expected to be small.
Therefore, even if the torque distribution control to the left and right rear wheels is discontinued during turning, the SMR is turned off after waiting for the vehicle speed and the absolute value of the left and right torque distribution to have no effect on the vehicle behavior. As a result, smooth fade-out of the left and right rear wheel torque distribution control is realized such that the torque to the left and right rear wheels is pulled out, and sudden changes in turning behavior can be suppressed.

Further, among the faults of the high-power system, it is the fault mode of the high-power battery 301, and when making a turn after transitioning to the battery-less running mode, step S5 to step S6 → step S7 → step S8 → step S9 in FIG. Proceed to In step S9, following the determination that the vehicle is turning in step S8, among the second motor 308 and the third motor 309 that individually drive the left and right rear wheels, the motor on the turning inner ring side regenerates, The motor on the turning outer wheel side is set to power running, and control is performed to cover the driving energy of the power running side motor with the power generated by the regenerative motor.
Therefore, even if the high-power system fails and the high-power battery 301 does not exist, the left and right rear wheels have a braking / driving torque difference (difference between the driving torque due to power running and the braking torque due to regeneration). The turning performance can be improved.
In other words, in the first embodiment, it is possible to minimize the deterioration of the turning performance such that the same performance as the turning performance when the high-power system is normal can be realized when the high-power system fails.

As described above, in the torque distribution control device according to the first embodiment, the high-power system failure detection unit (step S1) is provided to detect that a failure that requires prohibiting energization and charge / discharge of the high-power system occurs. The torque distribution control means (FIG. 2) does not limit the output torque of the motor until the torque distribution difference becomes a specified value or less when it becomes necessary to prohibit energization or charging / discharging due to the failure detection of the high power system.
As a result, during the execution of torque distribution control using the output torque of the motor, even if a failure of the high power system is detected, a stable vehicle behavior can be maintained when the motor system is off.

In the torque distribution control device according to the first embodiment, the torque distribution control means (FIG. 2) uses the specified value of the torque distribution difference that delays the limitation of the output torque of the motor, and stabilizes the vehicle behavior even when the torque distribution control is stopped. Is set to a value that can be secured.
For this reason, during execution of torque distribution control using the output torque of the motor, even if a failure of the high-power system is detected, stable vehicle behavior can be reliably maintained by appropriate motor system off timing.

In the torque distribution control device of the first embodiment, vehicle speed detection means for detecting the vehicle speed is provided, and the torque distribution control means (FIG. 2) needs to prohibit energization and charge / discharge by detecting a failure in the high-power system. At this time, if it is determined that the operating point has entered the control termination region in the control termination possibility determination map using the region where the torque distribution difference is smaller as the vehicle speed is higher, the SMR is turned off and the torque distribution control is terminated.
For example, the timing for turning off the SMR can be determined only by the torque distribution difference. However, when the prescribed value of the torque distribution difference is set based on the average vehicle speed during turning, the timing for turning off the SMR during high-speed turning is determined. If it is too early, the stability of the turning behavior may be impaired, and conversely, the timing for turning off the SMR during a low-speed turning may be too late, which may impair the protection function of the high voltage system.
On the other hand, in the first embodiment, since the torque distribution control is determined to be discontinued in consideration of the vehicle speed that affects the stability of the vehicle behavior, both the stability of the vehicle behavior and the protection function of the high voltage system are compatible. It is possible to determine whether to cancel the optimum torque distribution control.

In the torque distribution control device according to the first embodiment, a vehicle turning determination unit (step S2) for determining whether or not the vehicle is turning is provided, and the torque distribution control unit (FIG. 2) It is a means to control the torque distribution of the left and right rear wheels so that neutral steering characteristics can be obtained using the motor output torque. When it becomes necessary to prohibit energization or charging / discharging due to the failure detection of the high power system, If it is determined that the vehicle is not turning, the vehicle immediately shifts to a battery-less driving mode in which the SMR is turned off. If the vehicle is turning, the SMR waits for a decision to stop the torque distribution control for the left and right rear wheels. Transitions to a battery-less driving mode in which is turned off.
For this reason, when turning and torque distribution control are linked as in the first embodiment, a state in which there is no influence on the vehicle behavior is appropriately determined, while achieving a high protection function of the high-voltage system during straight traveling The stability of the turning behavior can be achieved during turning.

In the torque distribution control device according to the first embodiment, the hybrid vehicle includes an engine 305 and a first motor 303 that drive front wheels, a second motor 308 and a third motor 309 that individually drive left and right rear wheels, and the first vehicle. A hybrid four-wheel drive vehicle including a motor 303, a second motor 308, and a high-power system electrically coupled to the third motor 309, wherein the torque distribution control means (FIG. 2) When the system system failure detection means detects a failure of the high-power battery 301 as the failure mode, the second motor that individually drives the left and right rear wheels when turning after shifting to the battery-less travel mode using only the engine 305 as a drive source Among the 308 and third motor 309, the motor on the inner side of the turning is regenerated, the motor on the outer side of the turning is set to power running, and the driving energy of the power running side motor is determined by the energy generated by the regenerative motor. Cormorant.
For example, normally, when a high-power system fails, the mode is shifted to a battery-less travel mode using only the engine 305 as a drive source. However, in the system having the second motor 308 and the third motor 309 separately for the left and right rear wheels as in the first embodiment, if the CPU 101 and the RR inverter 307 are normal, a torque difference is caused by regeneration and power running. It is possible.
On the other hand, in the first embodiment, after shifting to the battery-less driving mode, a system having the second motor 308 and the third motor 309 for the left and right rear wheels is utilized to provide a torque difference between regeneration and power running. Therefore, it is possible to improve the turning performance by increasing the yaw moment in the turning direction even when the strong electric battery 301 is not present at the time of turning in the battery-less driving mode while minimizing the decrease in turning performance when the strong electric system fails. it can.

Next, the effect will be described.
In the torque distribution control device of the hybrid four-wheel drive vehicle of the first embodiment, the effects listed below can be obtained.

  (1) A high power system having an engine and a motor as drive sources and electrically coupled to the motor, and at least one of front and rear wheel torque distribution and left and right wheel torque distribution using the output torque of the motor In a torque distribution control device for a hybrid vehicle, comprising: a torque distribution control means for controlling; a high-power system failure detection means for detecting that a failure that requires prohibiting energization or charge / discharge of the high-power system has occurred (step) S1) is provided, and the torque distribution control means (FIG. 2) outputs the motor output until the torque distribution difference becomes a specified value or less when it becomes necessary to prohibit energization or charging / discharging due to the failure detection of the high power system. Since torque is not limited, even if a fault in the high-voltage system is detected during execution of torque distribution control using the output torque of the motor, it is safe when the motor system is off. The specified vehicle behavior can be maintained.

  (2) The torque distribution control means (FIG. 2) sets the specified value of the torque distribution difference that delays the limitation of the output torque of the motor to a value that can ensure the stability of the vehicle behavior even when the torque distribution control is stopped. During execution of torque distribution control using the output torque of the motor, even if a failure of the high-power system is detected, stable vehicle behavior can be reliably maintained by appropriate motor system off timing.

  (3) A vehicle speed detecting means for detecting the vehicle speed is provided, and the torque distribution control means (FIG. 2) is configured such that when it is necessary to prohibit energization or charging / discharging due to the failure detection of the high power system, the torque increases as the vehicle speed increases. When it is determined that the operating point has entered the control cutoff region in the control cutoff possibility determination map using the region where the distribution difference is small as the control cutoff region, the SMR is turned off and the torque distribution control is stopped. It is possible to make an optimal judgment on the termination of torque distribution control that achieves both the protection function of the high-power system.

  (4) The vehicle turning determination means (step S2) for determining whether or not the own vehicle is turning is provided, and the torque distribution control means (FIG. 2) uses the output torque of the motor during turning, It is a means to control the torque distribution of the left and right rear wheels so that neutral steer characteristics can be obtained, and it is determined that the vehicle is not turning when it is necessary to prohibit energization or charging / discharging due to the failure detection of the high power system When the vehicle is turning, it immediately shifts to a battery-less running mode in which the SMR is turned off. When the host vehicle is turning, a battery-less running in which the SMR is turned off after waiting for a judgment to stop the torque distribution control of the left and right rear wheels. In order to shift to the mode, when the strong electric system fails, the state where there is no influence on the vehicle behavior is properly judged, and while the high power system is highly protected when driving straight, the turning behavior is Stability can be achieved.

  (5) The hybrid vehicle includes an engine 305 and a first motor 303 that drive front wheels, a second motor 308 and a third motor 309 that individually drive left and right rear wheels, and the first motor 303 and the second motor. 308 and a strong electric system electrically coupled to the third motor 309, and the torque distribution control means (FIG. 2) has a fault in the strong electric system failure detection means. When a failure of the high-power battery 301 is detected as a mode, the second motor 308 and the third motor 309 that individually drive the left and right rear wheels during turning after shifting to the battery-less travel mode using only the engine 305 as a drive source Among them, the motor on the inner ring side is set to regenerate, the motor on the outer ring side is set to power running, and the driving energy of the power running motor is covered by the power generated by the regenerative motor. It is possible to improve the turning performance by increasing the yaw moment in the turning direction even when the high-power battery 301 is not present when turning in the battery-less running mode while minimizing the reduction in turning performance.

  The second embodiment is an example in which the left and right rear wheels are subjected to torque distribution control of the left and right rear wheels by one motor and a differential mechanism.

First, the configuration will be described.
FIG. 5 is an overall system diagram showing a hybrid four-wheel drive vehicle (an example of a hybrid vehicle) to which the torque distribution control device of the second embodiment is applied.
As shown in FIG. 5, the hybrid four-wheel drive vehicle of the second embodiment includes a CPU 101, an auxiliary battery 102, a high-power battery 301, an FR inverter 302, a first motor 303 (first motor), and a generator. 304, engine 305, power split mechanism 306, RR inverter 307, second motor 308 (second motor), differential mechanism 310 (left and right rear wheel torque distribution mechanism), accelerator sensor 401, brake sensor 402, a DC / DC converter 403, a steering angle sensor 404, a GPS 405, and a wheel speed sensor 406 are provided. The description of the configuration having the same function as the configuration of the first embodiment shown in FIG. 1 is omitted.

  The CPU 101 monitors the high-power battery 301, calculates the input / output possible electric energy according to the SOC, temperature, and deterioration state, and controls the FR inverter 302 based on this, thereby the first motor 303 (front drive) And the generator 304 are operated, and the engine 305 is controlled. Further, by controlling the RR inverter 307, the second motor 308 (for rear drive) is operated, and further, the steering to the differential mechanism 310 is instructed to distribute torque to the left and right wheels, thereby realizing neutral steer. Torque distribution control for front and rear wheels and torque distribution control for left and right rear wheels.

  The high-power battery 301 assists the traveling of the hybrid vehicle by supplying electric power to the first motor 303 via the FR inverter 302, and uses the electric power generated by the generator 304 via the RR inverter 307. And has a role to collect. When the second motor 308 is powered, the hybrid vehicle travel is assisted by supplying power via the RR inverter 307, and when the second motor 308 generates power, the power is supplied via the RR inverter 307. It also has the role of collecting power.

  The second motor 308 is for rear drive, and is responsible for the function as a 4WD hybrid vehicle during normal driving, and during turning, torque is generated due to the increase in the driving course caused by the difference between the inner wheels, thereby stabilizing driving and steering. Contributes to improved performance.

  The differential mechanism 310 has a function of distributing the torque generated by the second motor 308 to the left and right wheels. Specifically, in addition to a normal differential mechanism, a speed increasing mechanism, a right clutch, and a left clutch are provided in addition to a normal differential mechanism, and these are controlled according to a command from the CPU 101.

  The wheel speed sensor 406 detects the speed information of each wheel and transmits the information to the CPU 101.

  FIG. 6 is a flowchart showing the flow of torque distribution control processing executed by the CPU 101 of the second embodiment (torque distribution control means). In this flowchart, steps S21 to S26 are steps corresponding to steps S1 to S6 in FIG. 2, respectively.

  Next, with respect to the torque distribution control action, in the first embodiment, optimization control of torque distribution to the left and right rear wheels is performed by the second motor 308 and the third motor 308, whereas in the second embodiment, the left and right torque distribution control is performed. The difference is that optimization control of torque distribution to the rear wheels is performed by the second motor 308 and the differential mechanism 310. In addition, since the left and right rear wheels do not have the separate second motor 308 and third motor 308, as is apparent from the flowchart of FIG. 6, when turning after shifting to the battery-less running mode, The difference is that the motor is set to regenerate, the motor on the turning outer wheel side is set to power running, and the control to cover the drive energy of the power running motor with the power generated by the regenerative motor cannot be executed.

Next, the effect will be described.
In the torque distribution control device for the hybrid four-wheel drive vehicle of the second embodiment, in addition to the effects (1), (2), (3), (4) of the first embodiment, the following effects can be obtained. it can.

  (6) The hybrid vehicle drives the rear wheels via the engine 305 and the first motor 303 that drive the front wheels, and the differential mechanism 310 that can distribute the output torque to the left and right rear wheels at an arbitrary distribution ratio. Since it is a hybrid four-wheel drive vehicle including a motor 308 and a high-power system electrically coupled to the first motor 303 and the second motor 308, the output torque of the second motor 308 during turning During the execution of the torque distribution control of the left and right rear wheels using the wheel, stable turning behavior can be maintained when the motor system is off even if a failure of the high-power system is detected.

  As mentioned above, although the torque distribution control apparatus of the hybrid vehicle of this invention has been demonstrated based on Example 1 and Example 2, it is not restricted to these Examples about a concrete structure, Claim of Claim Design changes and additions are allowed without departing from the spirit of the invention according to each claim.

  In the first and second embodiments, the turning and the torque distribution control of the left and right rear wheels are linked such that the torque distribution of the left and right rear wheels is controlled so that the neutral steering characteristic is obtained by using the output torque of the motor at the time of turning. Although an example has been shown, the present invention can also be applied to a system that controls torque distribution between the front and rear wheels or the left and right wheels at the time of starting other than turning, at the time of acceleration / deceleration, or at the time of braking. Even during straight running, for example, on a low μ road, the control of the present invention is effective when the vehicle behavior is affected by a sudden change in the torque distribution of the front and rear wheels or the left and right wheels. In short, in a torque distribution control device for a hybrid vehicle that controls at least one of front and rear wheel torque distribution and left and right wheel torque distribution using the output torque of the motor, it is necessary to prohibit energization and charge / discharge by detecting a fault in the high-power system. If the torque distribution difference does not limit the output torque of the motor until the torque distribution difference becomes equal to or less than the specified value, it is included in the present invention.

  In the first and second embodiments, an example of application to a front four-wheel drive-based hybrid four-wheel drive vehicle is shown. However, the present invention can also be applied to a rear-wheel drive-based hybrid four-wheel drive vehicle, and the front wheels are driven only by an engine. The present invention can also be applied to a motor four-wheel drive vehicle (an example of a hybrid four-wheel drive vehicle) in which the rear wheels are driven only by a motor. Furthermore, the present invention can also be applied to a front-wheel drive hybrid vehicle or a rear-wheel drive hybrid vehicle that performs only torque distribution on the front and rear wheels or only distributes torque on the left and right wheels. In short, it has an engine and a motor as a drive source, and controls at least one of the front and rear wheel torque distribution and the left and right wheel torque distribution using the high-power system electrically coupled to the motor and the output torque of the motor. The present invention can be applied to any hybrid vehicle provided with torque distribution control means.

1 is an overall system diagram showing a hybrid four-wheel drive vehicle to which a torque distribution control device of Embodiment 1 is applied. 3 is a flowchart illustrating a flow of torque distribution control processing executed by a CPU according to the first embodiment. It is a figure which shows an example of the torque distribution control abortion possibility map at the time of turning used by torque distribution control of Example 1. FIG. System failure occurrence, steering angle sensor detection value (absolute value), motor rotation speed (= vehicle speed), second motor request torque, third motor request when a failure occurs in the high-voltage system in the torque distribution control of the first embodiment It is a time chart which shows each characteristic of torque and SMR. It is a whole system figure which shows the hybrid four-wheel drive vehicle to which the torque distribution control apparatus of Example 2 was applied. It is a flowchart which shows the flow of the torque distribution control process performed with CPU of Example 2. FIG.

Explanation of symbols

101 CPU
102 Auxiliary battery
301 Heavy battery
302 FR inverter
303 First motor (first motor)
304 generator
305 engine
306 Power split mechanism
307 Inverter for RR
308 Second motor (second motor)
309 Third motor (third motor)
310 differential mechanism (left and right rear wheel torque distribution mechanism)
401 Accelerator sensor
402 Brake sensor
403 DC / DC converter
404 Rudder angle sensor
405 GPS
406 Wheel speed sensor

Claims (4)

It has an engine and a motor as drive sources,
A high-voltage system electrically coupled to the motor;
Torque distribution control means for controlling at least one of front and rear wheel torque distribution and left and right wheel torque distribution using the output torque of the motor;
In a torque distribution control device for a hybrid vehicle equipped with
Providing a strong electric system failure detection means for detecting that a failure that requires prohibiting energization and charging / discharging of the strong electric system occurs;
The torque distribution control means does not limit the output torque of the motor until a torque distribution difference becomes a specified value or less when it is necessary to prohibit energization or charge / discharge due to failure detection of the high-power system. A torque distribution control device for a hybrid vehicle. In the hybrid vehicle torque distribution control device according to claim 1,
A torque distribution control device for a hybrid vehicle, wherein the torque distribution control means sets the specified value of the torque distribution difference to a value that can ensure the stability of the vehicle behavior even when the torque distribution control is stopped. In the torque distribution control device for a hybrid vehicle according to claim 1 or 2,
The hybrid vehicle includes an engine and a first motor that drive front wheels, a second motor that drives rear wheels via a left and right rear wheel torque distribution mechanism that can distribute output torque to the left and right rear wheels at an arbitrary distribution ratio, and A hybrid vehicle torque distribution control device comprising: a hybrid four-wheel drive vehicle including a high-power system electrically coupled to the first motor and the second motor . It has an engine and a motor as drive sources,
A high voltage system electrically coupled to the motor;
In the hybrid vehicle torque distribution control device for controlling at least one of the front and rear wheel torque distribution and the left and right wheel torque distribution using the output torque of the motor,
Torque distribution of a hybrid vehicle characterized by not limiting the output torque of the motor until a torque distribution difference becomes a specified value or less when it becomes necessary to prohibit energization or charge / discharge due to failure detection of the high-power system. Control device.

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