JP6365067B2 - Control device for electric four-wheel drive vehicle - Google Patents

Description

  The present invention relates to a control device in an electric four-wheel drive vehicle.

In order to stabilize the driving on the road such as sand, mud, snow and freezing, vehicles using a four-wheel drive system that transmits driving force to all four wheels and uses all four wheels as driving wheels have been used. Yes.
In addition to the drive shaft by the engine, an electric four-wheel drive vehicle in which the other axle is driven by a motor driven by electric power has been developed and used. The electric four-wheel drive vehicle eliminates the need for a propeller shaft that transmits power from the engine at the front of the vehicle body to the other axle, thereby improving the degree of freedom in designing the space under the vehicle's indoor feet, and saving oil resource fuel. It has the advantage that it can be achieved.

  As such an electric four-wheel drive vehicle, Patent Document 1 discloses an electric drive in which one drive wheel is driven by an engine and the other drive wheel is driven via an electric motor driven by electric energy generated by the engine. A four-wheel drive vehicle is described. An idling stop control means for automatically stopping and restarting the engine, and a four-wheel drive mode prohibiting control for prohibiting a four-wheel drive mode for controlling the driving of the electric motor during the engine restart by the idling stop control means. Means. As a result, the power consumption to the electric motor can be suppressed, and the restart after the automatic engine stop is promptly achieved by supplying the power only to the engine start.

  In Patent Document 2, the target driving force is obtained based on the degree of operation of the output operation means by the driver and the vehicle speed, controlled based on the vehicle state or the driving state of the vehicle, and the distribution of the driving force between the front and rear wheels is targeted. It is described that the change is made based on the driving force. In the case of a low target driving force that does not cause a slip, for example, the rear wheel driving force is reduced to reduce the power consumption of the motor for driving the rear wheels.

JP 2004-236425 A Japanese Patent No. 3646643

However, in Patent Document 1, until the engine start is completed, driving force cannot be obtained on one of the driving wheels, and only the other driving wheel travels with the driving force of the motor. When starting off on a slippery slope (low mud slope), there is a risk of starting acceleration.
Patent Document 2 describes how to control the distribution of driving force between the front wheels and the rear wheels when the engine is started with the front wheels and the rear wheels being driven by motors. Absent.

  The present invention has been made in view of such problems, and in an electric four-wheel drive vehicle, when the engine is started in a state where the front wheels and the rear wheels are driven by the motor, the front wheels are selected according to the road conditions. The purpose is to control the power distribution of the motor that drives the rear wheels.

In order to solve the above-described problem, the structural feature of the invention according to claim 1 is that an engine that can drive any one of the front wheels and the rear wheels, and a first motor that can drive the front wheels. A second motor capable of driving the rear wheel, a starter generator capable of starting the engine and generating electric power by the driving force of the engine, the first motor, the second motor, and the starter generator. a battery that allows supplying power, said the first motor and the second motor, the control device in the electric four-wheel drive vehicle having a power converter, a to a possible supply converts each electric power from the battery A starting power calculating unit for calculating a starting power required for starting the engine, and a climbing state in which the vehicle climbs a slope having a predetermined inclination angle or more. The engine is requested to start in a drive state where the first motor and the second motor are driven, and the climb state is detected by the climb state detection unit. If the reduction, by reducing the power supplied to the first motor from the power conversion device, a first motor power reduction unit that to ensure the pre-Symbol starting power by the first motor power reduction portion A first engine starting unit that starts the engine by the starter generator using the generated electric power.

According to the first invention, the uphill state detection unit detects whether or not the vehicle is in an uphill state where the vehicle climbs a slope with a predetermined inclination angle or more. And, when the first motor that drives the front wheels and the second motor that drives the rear wheels are driving, the engine is requested to start, and the uphill state detection unit detects that it is in the uphill state. The power supplied from the power converter to the first motor by the first motor power reduction unit is reduced so as to secure the starting power calculated by the starting power calculation unit. The first engine starter starts the engine using the reduced start output power.
When the vehicle is in an uphill state, the load applied to the front wheels is reduced, and the driving force that causes the front wheels to actually run the vehicle while gripping the road surface is reduced as compared to a flat ground running state. Since the electric power of the motor that drives the wheel having the reduced driving force is reduced for starting the engine in this way, it is possible to reduce the shock given to the driver due to the reduction of the driving force when the electric power is reduced. . Since the driving force of the rear wheel, which increases the driving force that actually drives the vehicle in the climbing state, does not decrease, even when climbing on a hill with a low coefficient of friction, the rear wheel grips securely, slipping and The vehicle can be prevented from sliding down.

It is a schematic diagram showing the whole electric four-wheel drive vehicle in a 1st embodiment. It is a block diagram which shows the outline | summary of the control apparatus of an electric four-wheel drive vehicle. It is a flowchart which shows the control which reduces the driving force of a motor in order to perform an engine start. It is a figure showing the case where an engine is started by reducing the driving force of the electric motor which transmits a driving force to a rear wheel. It is a figure showing the case where an engine is started by reducing the driving force of the electric motor which transmits a driving force to a front wheel. It is a figure which shows the usage distribution of the battery electric power in normal motor driving | running | working, and the usage distribution of the battery electric power when an engine start is performed. It is explanatory drawing in the case of detecting that a vehicle is in a climbing state on a slope. It is a schematic diagram showing another example of an electric four-wheel drive vehicle provided with a step-up / down circuit.

<First Embodiment>
A first embodiment of a control device for an electric four-wheel drive vehicle according to the present invention will be described with reference to FIGS.
FIG. 1 is a diagram showing a schematic configuration of an electric four-wheel drive vehicle. The electric four-wheel drive vehicle 10 of the first embodiment includes an engine 12, a first motor 14, an automatic transmission 16, a battery 18, a front wheel drive inverter 20, a rear wheel drive inverter 22, and a starter. Generator 24, charge capacity detection device 26, second motor 28, speed reducer 30, driving force control device 32 as a control device, first motor control device 34, second motor control device 36, acceleration A sensor 38 and a vehicle speed sensor 40 are included.

  The engine 12 is a normal internal combustion engine that generates an output from a hydrocarbon-based fuel, and is provided on the front side of the vehicle 10 so that the front wheels Wf can be driven. However, the invention is not limited to the internal combustion engine using hydrocarbon fuel, and any drive source that drives the output shaft may be used. The engine 12 is provided with an engine speed sensor 13 that detects the speed of the output shaft of the engine.

The first motor 14 is, for example, a DC brushless motor, and is an AC synchronous motor generator that is driven with an alternating current in which a permanent magnet is embedded in a rotor (not shown) and a stator coil is wound around a stator (not shown). . The first motor 14 is provided so as to be able to drive the front wheels Wf.
The engine 12 and the first motor 14 are connected in series via a clutch 42 that is a wet multi-plate clutch. The clutch 42 interrupts torque transmission by connecting and disconnecting the connection between the engine 12 and the first motor 14 by a hydraulic control circuit (not shown). The clutch 42 is a normally closed type clutch that normally connects the engine 12 and the first motor 14. When the clutch 42 is connected, the rotational torques of the engine 12 and the first motor 14 are both transmitted to the input shaft (not shown) of the automatic transmission 16, and when the clutch 42 is disconnected, the rotation of the first motor 14 is performed. Only torque is transmitted to the input shaft of the automatic transmission 16.

The automatic transmission 16 includes, for example, a dog clutch type transmission mechanism (not shown) capable of selecting six forward speeds and one reverse speed, and a differential gear mechanism (not shown). The speed change by the speed change mechanism and the differential gear mechanism reduce the rotational speed of the rotational torque from the engine 12 or the first motor 14, and transmit the reduced rotational torque to the drive shafts 17 of the left and right front wheels Wf.
A part of the rotational torque of the engine 12 is transmitted to the starter generator 24 via, for example, an endless belt (not shown). The starter generator 24 generates power when the rotor (not shown) rotates by driving the engine 12, and supplies the generated power to the battery 18 to charge the battery 18. Further, the engine 12 can be started by rotating the rotor by the electric power from the battery 18.

The battery 18 is a chargeable / dischargeable secondary battery such as a nickel metal hydride battery or a lithium ion battery. The battery 18 is electrically connected to the first motor 14 that drives the front wheels Wf of the vehicle 10, and is electrically connected to the second motor 28 that drives the rear wheels Wr of the vehicle 10.
The battery 18 is managed by the battery control unit 44. The battery 18 is provided with a charge capacity detection device 26, which calculates a charge capacity SOC (State Of Charge) based on a current sensor (not shown), a charge / discharge current detected by a voltage sensor, and a voltage between terminals. Detected by device 26. The detected data is sent to the battery control unit 44. The battery 18 is cooled and managed by a temperature sensor (not shown).

  The second motor 28 is, for example, a DC brushless motor, like the first motor 14, and is driven by an alternating current in which a permanent magnet is embedded in a rotor (not shown) and a stator coil is wound around a stator (not shown). This is an AC synchronous motor generator. The second motor 28 is connected to the speed reducer 30. The speed reducer 30 includes a differential mechanism (not shown) that reduces the rotational speed of the rotational torque of the second motor 28 and distributes the rotational torque to the drive shafts 46 of the left and right rear wheels Wr.

A front wheel drive inverter 20 and a rear wheel drive inverter 22 are electrically connected to the battery 18.
The front-wheel drive inverter 20 includes a switching element (not shown), converts a DC current from the battery 18 into a three-phase AC current by a switching operation of the switching element, and a stator (not shown) of the first motor 14. To each phase of the stator winding. Thus, by applying the electric power from the battery 18 to the first motor 14, the rotational drive of the first motor 14 that drives the front wheels Wf is controlled. A first motor control device 34 is electrically connected to the front wheel drive inverter 20. The first motor control device 34 controls the switching operation of the front-wheel drive inverter 20.

The rear-wheel drive inverter 22 has the same configuration as that of the front-wheel drive inverter 20 and applies the electric power from the battery 18 to the second motor 28 to drive the rotation of the second motor 28 that drives the rear wheel Wr. Control. The rear wheel drive inverter 22 and the front wheel drive inverter 20 constitute a power converter.
The first motor control device 34 and the second motor control device 36 are connected to the driving force control device 32 by a CAN (Controller Area Network), and are managed and controlled, respectively.

  The driving force control device 32 is supplied with an accelerator opening detection signal indicating the amount of depression of the accelerator pedal (not shown) of the vehicle, and with a detection signal indicating the vehicle speed from the vehicle speed sensor 40. In addition, a detection signal representing engine torque is sent to the driving force control device 32 by an engine torque sensor (not shown). In the driving force control device 32, for example, the required torque calculated from the accelerator opening is compared with the total motor torque by the first and second motors 14 and 28, and the engine 12 is compared when the total motor torque is smaller than the required torque. Is executed to compensate for engine torque.

The left and right front wheels Wf are each provided with a front wheel vehicle speed sensor 40f that detects the vehicle speed from the wheel speed, and the left and right rear wheels Wr are similarly provided with rear wheel vehicle speed sensors 40r that respectively detect the vehicle speed from the wheel speed. Vehicle speed detection signals detected by the front wheel speed sensor 40f and the rear wheel speed sensor 40r are sent to the driving force control device 32 via the CAN.
The electric four-wheel drive vehicle 10 is provided with an acceleration sensor 38 that detects the longitudinal acceleration of the vehicle. The acceleration sensor 38 constitutes a part of an uphill state detection unit, and an acceleration detection signal detected by the acceleration sensor 38 is sent to the driving force control device 32 via the CAN.

As shown in FIG. 2, the driving force control device 32 includes a calculation unit 47, a storage unit 49, and a control unit 51. The calculation unit 47 detects whether the vehicle 10 is detected by a detection signal from a start power calculation unit 48 that calculates start power required for starting the engine 12 and an acceleration sensor 38 that detects the running state of the vehicle and the traveling road surface during vehicle running or the like. And a climbing state detection unit 50 for detecting whether or not the climbing state is performed on a slope having a predetermined inclination angle or more.
The storage unit 49 stores data input from each sensor and data calculated by the calculation unit 47. For example, the electric power required for starting the engine changes with the passage of time, is calculated by the starting electric power calculation unit 48 including the change characteristics, and is stored in the storage unit 49 in advance.

The control unit 51 includes a first engine start unit 54, a second engine start unit 58, and a battery control unit 44. The first engine starting unit 54 starts the engine 12 by the starter generator 24 using the power reduced by the first motor power reducing unit 52 described later. The second engine starting unit 58 starts the engine 12 by the starter generator 24 using the power reduced by the second motor power reducing unit 56 described later.
The battery control unit 44 performs detection / control of the charge capacity of the battery 18, temperature management of the battery 18, and the like.

The control unit 51 is connected to the first motor control device 34 and the second motor control device 36, which are subordinate control devices, so as to be able to output electrical signals. The first motor control device 34 starts when the starting power calculation unit 48 calculates the power supplied from the front wheel drive inverter 20 to the first motor 14 when the climbing state is detected by the climbing state detection unit 50. It has the 1st motor electric power reduction part 52 which reduces so that electric power may be ensured.
The second motor control device 36 calculates the power supplied from the rear-wheel drive inverter 22 to the second motor 28 by the starting power calculation unit 48 when the climbing state detection unit 50 does not detect the climbing state. The second motor power reduction unit 56 is provided to reduce the starting power.

(Engine starting procedure)
Next, the control procedure of the program for starting the engine using the control device for the electric four-wheel drive vehicle having the above configuration will be described with reference to the flowchart of FIG.
First, in step 100 (hereinafter, “step” is abbreviated as “S”; the same applies in FIG. 3), the driving force control device 32 is in a state where the first motor 14 and the second motor 28 are driven. Determine whether or not. That is, it is determined whether or not the front wheel Wf is driven by the first motor 14 and the rear wheel Wr is driven by the second motor 28. As a premise, the engine 12 is in a stopped state.
When the driving force control device 32 determines that the first motor 14 and the second motor 28 are driven, the process proceeds to S101. When the driving force control device 32 determines that the first motor 14 and the second motor 28 are not driven, the program ends.

When it is determined that the first motor 14 and the second motor 28 are driven, the driving force control device 32 determines whether the engine 12 needs to be started (S101). Examples of the case where the engine 12 needs to be started include (1) the case where the charging capacity of the battery 18 is insufficient and the engine 12 is started to drive the starter generator 24 and charge the battery 18.
As the other engine 12 needs to be started, (2) the torque required for the driver (accelerator depression) exceeds the limit of the torque output by the first motor 14 and the second motor 28, and the first motor 14 and In addition to the driving torque of the second motor 28, a driving torque by the engine 12 may be required.
Further, (3) the vehicle speed is higher than a predetermined value, the required driving torque may exceed the output limit of the driving torque by the first motor 14 and the second motor 28, and the driving by the motor torque may be switched to the driving by the engine torque. .
When the driving force control device 32 determines that the engine start is not necessary, the driving force control device 32 ends the control for starting the engine.

  When it is determined that the engine 12 needs to be started, the driving force control device 32 proceeds to S102 and determines whether or not the engine can be started with the current charge capacity (SOC) of the battery 18 (S102). S102). Whether the engine can be started with the current SOC of the battery 18 is determined, for example, as follows. First, the power that can be output from the battery 18 is calculated by the calculation unit of the driving force control device 32 from the current SOC value detected by the charge capacity detection device 26 of the battery 18. For the electric power necessary for starting the engine, data stored in advance in the storage unit 49 of the driving force control device 32 is read and used.

  The driving force control device 32 sums the required power corresponding to the driver's required accelerator depression amount and the power required for starting the engine. The total required power and the power required for starting the engine are compared with the power that can be output by the battery 18. If the total required power and the power necessary for starting the engine are larger than the power that can be output from the battery 18, it is determined that the engine cannot be started using the current SOC of the battery 18, and the process proceeds to S103. .

  When the total of the required power corresponding to the required accelerator depression amount and the power required for starting the engine is smaller than the power that can be output from the battery 18, the driving force control device 32 determines that the engine start is based on the SOC of the current battery. It is determined that it is possible, and the process proceeds to S106 and the engine 12 is started.

If it is determined in S102 that engine start is not possible with the current SOC of the battery 18, the driving force control device 32 drives the first motor 14 and the second motor 28 so as to secure electric power necessary for engine start. The amount of force reduction is calculated (S103).
That is, the difference obtained by subtracting the power that can be output by the battery 18 with the current charging capacity from the total of the required power corresponding to the required accelerator depression amount and the power required for engine start is defined as the reduction amount of the driving force (power).

  “Reducing to ensure starting power” conceptually means reducing at least part of the power required for starting the engine 12 from the power consumption of the first motor 14 or the power consumption of the second motor 28. Means. (In this case, the remainder of the electric power necessary for starting the engine 12 is supplied from the suppliable electric power remaining in the battery 18).

  When the reduction amount of the driving force of the first motor 14 and the second motor 28 is calculated in S103, the process proceeds to S104, and the driving force control device 32 causes the uphill state detection unit 50 to check that the vehicle 10 is equal to or greater than a predetermined inclination angle. It is determined whether or not the hill is in an uphill state (S104). For example, 10 degrees is set as the predetermined inclination angle. The inclination angle while the vehicle 10 is traveling is obtained as follows. The acceleration A1 in the traveling direction of the vehicle 10 is obtained by differentiating the vehicle speed detected by the vehicle speed sensors 40f and 40r. Further, as shown in FIG. 7, the gravity that affects the traveling direction of the vehicle 10 acts in the direction of decelerating by GsinΘ if the slope with the inclination angle Θ is in the climbing state. Therefore, the acceleration A2 obtained by the acceleration sensor 38 is detected as a value smaller than the acceleration A1 calculated based on the vehicle speeds of the vehicle speed sensors 40f and 40r by the influence of gravity of GsinΘ. Therefore, the driving force control device 32 calculates GsinΘ by subtracting the acceleration A2 obtained by the acceleration sensor 38 from the acceleration A1 obtained by the vehicle speed sensors 40f and 40r (GsinΘ = A1-A2), and obtains the inclination angle Θ.

When the driving force control device 32 determines that the slope having an inclination angle of 10 degrees or more is in the climbing state, the driving force control device 32 proceeds to S105, and causes the first motor 14 to drive the front wheels Wf as shown in FIGS. 5 and 6. The reduced power supplied by the front-wheel drive inverter 20 is calculated (S105).
The reduced electric power of the first motor 14 supplied is calculated as follows.
The required power corresponding to the required accelerator depression amount is distributed to the drive distribution of the first motor 14 that drives the front wheels Wf and the second motor 28 that drives the rear wheels Wr (for example, first motor: second motor = 7: 3). The driving force (electric power) of the first motor 14 is calculated by distributing the power accordingly. The difference obtained by subtracting the power reduction amount obtained in S103 from the power of the first motor 14 is the power supplied to the first motor 14 (FIG. 6C).
In this case, the driving force control device 32 supplies the reduced electric power of the first motor 14 to the first motor 14 by the front wheel drive inverter 20.

  Next, the process proceeds to S106, and the driving force control device 32 is necessary for starting the engine that can be supplied from the battery 18 by reducing the power supplied from the front-wheel drive inverter 20 to the first motor 14. The engine 12 is started using electric power (S106). The engine speed sensor 13 detects that the engine 12 has been started, and the detected signal is sent to the driving force control device 32.

When the electric four-wheel drive vehicle 10 is in an uphill state, the vehicle 10 tilts backward, so that the center of gravity of the vehicle 10 moves to the rear wheel Wr side and the load applied to the front wheel Wf decreases. Therefore, the driving force for the front wheels Wf to grip the road surface and actually drive the vehicle 10 is reduced.
On the other hand, since the load applied to the rear wheel Wr is increased when the vehicle is in an uphill state, the driving force for actually driving the vehicle 10 while the rear wheel Wr grips the road surface, contrary to the front wheel Wf. Will increase.
As a result, the ratio of the driving force of the rear wheel Wr increases with respect to the driving force of the front wheel Wf.

Further, in the uphill state, the power supplied to drive the front wheels Wf having such a small driving force is reduced for starting the engine, so that the driver is reduced due to the reduction of the driving force when the power is reduced. The shock given to can be reduced.
Further, since the vehicle is tilted backward in the uphill state, the seating position of the occupant including the driver is also deviated toward the rear wheel Wr. However, the driving force (electric power) is reduced on the front wheel Wf side where the driving force is reduced, and the engine is reduced. Since it starts, it reduces the sense of incongruity felt by passengers.

  It should be noted that the distribution of the driving force on a flat road is, for example, where the first motor: second motor = 7: 3, and the first motor: second motor = 6 in a climbing state of a slope with a predetermined inclination angle or more. : By changing to 4, the driving force is applied to the rear wheel Wr more remarkably. As described above, when the distribution of the driving force is changed so that the rear wheel Wr becomes larger and control is performed to reduce the electric power supplied to the first motor 14 on the front wheel Wf side, the uncomfortable feeling given to the driver can be further reduced. .

In S104, when the driving force control device 32 determines that the slope having an inclination angle of 10 degrees or more is not in the climbing state, the process proceeds to S107, and the second motor 28 that drives the rear wheels Wr as shown in FIG. The reduced power supplied from the rear-wheel drive inverter 22 is calculated (S107).
Even in this case, the driving power (electric power) of the second motor 28 is calculated by distributing the required power corresponding to the required accelerator depression amount according to the driving distribution of the second motor 28 that drives the rear wheels Wr. The amount of reduction of the driving force (electric power) obtained in S103 is taken as the electric power supplied to the second motor 28 with reduced difference obtained by subtracting the driving force (electric power) of the second motor 28 (FIG. 6B).
In this case, the driving force control device 32 supplies the reduced electric power of the second motor to the second motor 28 by the rear wheel driving inverter 22.

When the power supplied to the second motor 28 for driving the rear wheel Wr is reduced, the process proceeds to S106, and the power supplied from the rear wheel drive inverter 22 to the second motor 28 is reduced. The engine 12 is started using the electric power necessary for starting the engine that can be supplied (S106).
When the engine 12 is started, a necessary driving torque is secured by the engine torque, and the starter generator 24 is rotated by the engine 12 to charge the battery 18.
Further, when the engine is started, the driving torque of the engine 12 is added to the driving torque of the first motor 14 and the second motor 28 to satisfy the torque required by the driver (accelerator depression).
In addition, when the engine is started, the vehicle is switched from running with motor torque to running with engine torque, and the vehicle speed is higher than a predetermined level.
This completes the control for starting the engine.

Second Embodiment
Next, a second embodiment that embodies the control device for a dynamic four-wheel drive vehicle of the present invention will be described with reference to FIG. This embodiment is different from the first embodiment in that a step-up / step-down circuit 62 is provided between the battery 18 and the front-wheel drive inverter 20 and the rear-wheel drive inverter 22. Since other configurations are the same as those of the first embodiment, the same reference numerals are given and description thereof is omitted.

According to this, the step-up / step-down circuit 62 is provided between the battery 18 and the front-wheel drive inverter 20 and the rear-wheel drive inverter 22. The first and second motors 14 and 28 can be driven by a voltage higher than that of the battery 18 by the step-up / step-down circuit 62 serving as a booster circuit, and loss due to heat generated by the first motor 14 and the second motor 28 is suppressed. Can do. Further, when regeneration is performed by the first motor 14 and the second motor 28, the voltage from the front-wheel drive inverter 20 and the rear-wheel drive inverter 22 is lowered to an appropriate voltage by the step-up / step-down circuit 62 that functions as a step-down circuit. 18 is charged. Thereby, the withstand voltage of the battery 18 can be designed low.
Other functions and effects are the same as those of the first embodiment.

  As apparent from the above description, the control device for the electric four-wheel drive vehicle according to the first embodiment and the second embodiment includes the engine 12 that can drive any one of the front wheels Wf and the rear wheels Wr. The first motor 14 that can drive the front wheels Wf, the second motor 28 that can drive the rear wheels Wr, and the starter generator 24 that can start the engine 12 and generate power by the driving force of the engine 12; The battery 18 that can supply power to the first motor 14, the second motor 28, and the starter generator 24, and the power from the battery 18 can be converted and supplied to the first motor 14 and the second motor 28, respectively. Electricity equipped with a front wheel drive inverter 20 and a rear wheel drive inverter 22, and a charge capacity detection device 26 that detects the charge capacity of the battery 18. The driving force control device 32 in the wheel drive vehicle 10 includes a starting power calculation unit 48 that calculates a starting power necessary for starting the engine 12, and the electric four-wheel drive vehicle 10 climbs a slope having a predetermined inclination angle or more. The engine 12 is requested to start in a driving state in which the first motor 14 and the second motor 28 are driven, and the uphill state detecting unit 50 detects whether the uphill state is detected. A first motor power reduction unit 52 that reduces the power supplied from the front-wheel drive inverter 20 to the first motor 14 to ensure the starting power calculated by the starting power calculation unit 48 when the state is detected; A first engine starting unit 54 that starts the engine 12 by the starter generator 24 using the power reduced by the first motor power reducing unit 52.

According to this, the uphill state detection unit 50 detects whether or not the electric four-wheel drive vehicle 10 is in an uphill state where it climbs a slope with a predetermined inclination angle (10 degrees) or more.
The engine 12 is requested to start while the first motor 14 that drives the front wheels Wf and the second motor 28 that drives the rear wheels Wr are driven, and the uphill state detection unit 50 performs a predetermined inclination. When it is detected that the vehicle is in a climbing state in which an uphill of an angle (10 degrees) or more is detected, the first motor power reduction unit 52 uses the power supplied from the front-wheel drive inverter 20 to the first motor 14 as a charging capacity. Based on the electric power that can be supplied from the battery 18 detected by the detection device 26, the starting power calculated by the starting power calculator 48 is reduced. The first engine starter 54 starts the engine 12 using the electric power corresponding to the reduced start output.
Thus, in the uphill state, the load applied to the front wheel Wf is reduced, and the electric power supplied to drive the front wheel Wf with the driving force for actually driving the vehicle 10 by gripping the road surface is reduced. Since it is reduced for starting, the shock applied to the driver can be reduced by reducing the driving force when the electric power is reduced. Since the driving force of the rear wheel Wr, which increases the driving force in the climbing state, is not reduced, the road surface is reliably gripped by the rear wheel Wr even on a hill climbing on a hill with a low coefficient of friction, and the slack of driving due to slipping or the vehicle 10 The sliding down can be prevented.

As described above, the control device for the electric four-wheel drive vehicle 10 according to the first embodiment and the second embodiment uses the rear wheel drive inverter 22 when the climbing state detection unit 50 does not detect the climbing state. The second motor power reduction unit 56 that reduces the power supplied to the second motor 28 so as to secure the starting power calculated by the starting power calculation unit 48, and the power reduced by the second motor power reduction unit 56 are used. And a second engine starter 58 for starting the engine 12 by the starter generator 24.
According to this, when the climbing state detection unit 50 detects that the climbing state is not equal to or greater than the predetermined inclination angle (10 degrees), the second motor power reduction unit 56 supplies the rear wheel drive inverter 22 to the second motor 28. The generated power is reduced so as to secure the starting power calculated by the starting power calculation unit 48. The second engine starter 58 starts the engine 12 using the reduced start output power.
When the electric four-wheel drive vehicle 10 is in a flat ground running state or a downhill state, the driving force of the rear wheel Wr that causes the rear wheel Wr to grip the road surface and actually drive the electric four-wheel drive vehicle 10 is the electric four-wheel drive. Less than when the vehicle 10 is in an uphill state. Since the electric power of the second motor 28 that drives the rear wheel Wr having a small driving force is reduced for starting the engine 12, a shock given to the driver due to the reduction of the driving force when the electric power is reduced. Can be reduced.

As described above, in the control device for the electric four-wheel drive vehicle 10 according to the present embodiment, the engine 12 is provided on the front side of the electric four-wheel drive vehicle 10 and can drive the front wheels Wf.
According to this, the front wheel Wf can be driven by the engine 12 and the first motor 14, and a device for transmitting the driving force of the engine 12 to the rear wheel Wr is unnecessary. 10 can be used.

As described above, in the control device for the electric four-wheel drive vehicle 10 according to the present embodiment, when the engine 12 is requested to start, the charging capacity of the battery 18 is insufficient, and the starter generator 24 is driven to This is a case where the engine 12 is started for charging.
When the charging capacity of the battery 18 is insufficient, it is necessary to charge the battery 18 by driving the starter generator 24 by the engine 12. In this way, the charging capacity of the battery 18 is reduced, and the power required for driving the first motor 14, the second motor 28, and starting the engine 12 can be output simultaneously due to the lack of charging capacity of the battery 18. In the case where there is no power, the electric power of any one of the batteries 18 output to the first motor 14 or the second motor 28 can be reduced, and the engine 12 can be reliably started using the reduced electric power.

Although the climbing state of the electric four-wheel drive vehicle 10 is detected based on the acceleration sensor 38 and the vehicle speed sensor 40, the present invention is not limited to this. For example, a well-known method for detecting the angular velocity in the vertical tilt direction of the vehicle is known. An angular velocity sensor (gyro) may be used. In this case, using the clock signal of the vehicle clock mechanism, the detected angular velocity is integrated over time, and the change angle ΔΘ in the vertical direction of the vehicle, which is the difference from the initial angle set on the flat ground, is obtained.
In the present embodiment, the predetermined inclination angle in the uphill state is 10 degrees, but is not limited thereto, and may be 8 degrees, for example. According to the friction coefficient mu between the road surface of the hill and the vehicle wheel, a predetermined inclination angle that does not cause a shock to the driver can be arbitrarily set by reducing the driving force of the front wheels.

Further, the clutch 42 is provided between the engine 12 and the first motor 14, but the present invention is not limited to this. For example, a power distribution mechanism using a planetary gear mechanism may be provided. When the power distribution mechanism is provided, for example, the output shaft of the engine is directly connected to the carrier, the rotation shaft (rotor) of the first motor is directly connected to the ring gear, and the rotation shaft of the starter generator is directly connected to the sun gear.
Further, as the inverter, two inverters were used: a front-wheel drive inverter 20 that supplies power to the first motor 14 and a rear-wheel drive inverter 22 that supplies power to the second motor 28. However, the present invention is not limited to this. For example, one inverter that supplies power to the first motor 14 and the second motor 28 may be used.

  Thus, the specific configuration described in the above-described embodiment is merely an example of the present invention, and the present invention is not limited to such a specific configuration. Various embodiments can be adopted without departing from the scope.

10: Electric four-wheel drive vehicle, 12: Engine, 14: First motor, 18: Battery, 20: Inverter for driving front wheel (power converter), 22: Inverter for driving rear wheel (power converter), 24: Starter Generator 26: charge capacity detection device 28: second motor 32: driving force control device (control device) 38: acceleration sensor 40f: front wheel vehicle speed sensor (vehicle speed sensor) 40r: rear wheel vehicle speed sensor (vehicle speed sensor) ), 48: starting power calculating unit, 52: first motor power reducing unit, 54: first engine starting unit, 56: second motor power reducing unit, 58: second engine starting unit, Wf: front wheel, Wr: rear ring.

Claims (4)

An engine that can drive either the front wheel or the rear wheel;
A first motor capable of driving the front wheels;
A second motor capable of driving the rear wheel;
A starter generator capable of starting the engine and generating power by the driving force of the engine;
A battery capable of supplying power to the first motor, the second motor, and the starter generator;
The first motor and the second motor, a power conversion device which can be supplied to convert the power from the battery, respectively,
A control apparatus in an electric four-wheel drive vehicle having a
A starting power calculator for calculating a starting power required for starting the engine;
A climbing state detection unit for detecting whether the vehicle is in a climbing state for climbing a slope with a predetermined inclination angle or more;
In a driving state where the first motor and the second motor are driven, when the engine is requested to start, and when the climbing state is detected by the climbing state detection unit, the first power converter converts the first by reducing the power supplied to the motor, the first motor power reduction unit that to ensure the pre-Symbol starting power,
A first engine starting unit for starting the engine by the starter generator using the power reduced by the first motor power reducing unit;
A control device for an electric four-wheel drive vehicle. When the climbing state is not detected by the climbing state detection unit, the power supplied from the power converter to the second motor is reduced so as to secure the starting power calculated by the starting power calculation unit. A second motor power reduction unit;
A second engine starter for starting the engine by the starter generator using the power reduced by the second motor power reducer;
The control device for an electric four-wheel drive vehicle according to claim 1, further comprising: The electric motor according to claim 1 or 2 , wherein when the engine is requested to start, the SOC of the battery is insufficient, and the engine is started to drive the starter generator to charge the battery. A control device for a four-wheel drive vehicle. The amount of power supplied to the first motor or the second motor can be reduced by the current SOC from the sum of the required power corresponding to the required accelerator depression amount and the power required for starting the engine. The control device for an electric four-wheel drive vehicle according to any one of claims 1 to 3, wherein the control device is obtained as a difference obtained by subtracting a large amount of electric power.

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