JP3742231B2 - Control device for front and rear wheel drive vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a front/rear wheel drive vehicle controller which can properly prevent the delay of the power generation of a generator driven by an engine from causing delay in assisted driving by an electric motor. SOLUTION: In addition to a generator 24, which is driven to rotate by an engine 10 for supplying electrical energy to an MG 28, a capacitor (power storage device) 48, is provided. When the MG 28 is driven in order to assist a pulling force at starting of a vehicle, electrical energy is supplied to the MG 28 from the generator 24 and the capacitor 48 simultaneously by a cooperative feeding means 84, so that the driving torque of the MG 28 becomes obmpf in its rise. With this constitution, the delay of the assistant driving of the MG 28 which is caused by the delay of the power generation of the generator 24 can be avoided properly, and the slippage of main drive wheels (front wheels 20) can be suppressed properly.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a front and rear wheel drive vehicle in which one of a front wheel drive system and a rear wheel drive system uses an engine as a drive source and the other uses an electric motor as a drive source.
[0002]
[Prior art]
There is known a vehicle in which one of a front wheel drive system and a rear wheel drive system uses an engine (internal combustion engine) as a drive source and the other uses an electric motor as a drive source. Such a vehicle is also referred to as an electric four-wheel drive vehicle because it enters a four-wheel drive state when the other drive system is driven by an electric motor while one drive system is driven by an engine. In this electric four-wheel drive vehicle, when it becomes a predetermined motor drive region that requires acceleration of the vehicle in order to improve the driving ability of the vehicle as a whole and maintain fuel efficiency or vehicle characteristics at a good level. Only the electric motor is driven and assist torque is applied to the vehicle.
[0003]
In the front and rear wheel drive vehicle as described above, a generator that is rotationally driven by an engine is provided, and the electric motor is driven by supplying electric energy generated by the generator to the electric motor. It has been proposed to eliminate the need for a high-voltage battery and reduce the size of the electric motor. For example, it is a control device for a front and rear wheel drive vehicle described in Japanese Patent Laid-Open No. 8-126117.
[0004]
[Problems to be solved by the invention]
However, when the electric energy is directly supplied to the electric motor from the generator that is rotationally driven by the engine as described above, if the electric energy supplied from the generator to the electric motor is from zero, Since a slight delay time occurs, for example, when the electric motor is driven to start the vehicle on a steep uphill road, the assist drive by the electric motor is delayed due to the power generation delay, so the drive driven by the engine There is a disadvantage that the case where the slip of the wheel cannot be suppressed occurs.
[0005]
The present invention has been made against the background of the above circumstances, and the object of the present invention is before and after the delay of the assist drive by the electric motor due to the power generation delay of the generator driven by the engine is suitably prevented. The object is to provide a control device for a wheel drive vehicle.
[0006]
[Means for Solving the Problems]
In order to achieve this object, the gist of the present invention includes a generator driven by an engine and an electric motor driven by the generator, and one of a front wheel drive system and a rear wheel drive system. Is a control device for a front and rear wheel drive vehicle in which the engine is a drive source and the other is the electric motor as a drive source, and (a) a power storage device, and (b) when driving the electric motor,Determine if it is necessary to start up the electric motor quickly, and when it is necessary to start up quicklyCoordinate power feeding means for simultaneously supplying the electric motor with the electric energy from the generator and the electric energy from the power storage device is included.
[0007]
【The invention's effect】
In this way, in addition to the generator driven by the engine to supply electric energy to the electric motor, the power storage device is provided, and when driving the electric motor,Determine if it is necessary to start up the electric motor quickly, and when it is necessary to start up quicklySince the electric power from the generator and the electric energy from the power storage device are supplied to the electric motor at the same time by the cooperative power supply means, the rise of the driving torque of the electric motor becomes rapid. The delay of the assist drive by the electric motor due to the power generation delay of the driven generator is preferably prevented, and the slip of the drive wheel driven by the engine at the start of the vehicle is suitably suppressed, so that the vehicle travels on an uphill road or the like Performance is improved.
[0008]
Other aspects of the invention
Here, preferably, the power storage device is a capacitor that stores electric energy by polarization of a dielectric, and the amount of electric energy that is deficient due to a power generation delay of a generator to quickly start up output torque by the electric motor. It has a capacity to store. In this way, since the electrical energy stored in the capacitor is rapidly output, the drive torque of the electric motor can be further increased.
[0009]
Preferably, a gradient detection device that detects a gradient of a traveling road surface of the front and rear wheel drive vehicle, and electric energy supplied from the power storage device to the electric motor in accordance with the gradient detected by the gradient detection device. And a power source switching means for switching the ratio of the supply amount. In this way, the ratio of the amount of electric energy supplied from the power storage device to the electric motor is switched according to the road surface gradient. For example, as the gradient becomes smaller, the ratio of the amount of electric energy supplied from the power storage device to the electric motor is reduced, so that the consumption of electric energy stored in the power storage device is reduced.
[0010]
Preferably, control end charging means for storing power in the power storage device by power generation by the generator based on the amount of power stored in the power storage device immediately after driving of the electric motor is provided. In this way, when the electric motor is repeatedly driven, there is an advantage that the drive torque of the next electric motor rises rapidly.
[0011]
Preferably, the drive of the electric motor is performed during a period in which the traction force of the drive wheel is insufficient due to the occurrence of slip of the drive wheel driven by the engine. If the forward / rear wheel drive vehicle cannot move forward regardless of this, the load on the engine's auxiliaries can be maximized, the transmission gear speed can be increased, and the friction engagement devices in the transmission can be overlapped. Engine load increasing means for executing at least one control of the engine and further reducing the driving force of the driving wheels driven by the engine. In this way, when the vehicle starts, in a state where slip occurs on the drive wheels driven by the engine, the engine load is increased and the slip of the wheels driven by the engine is suppressed. The traction force of the vehicle is increased.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
[0013]
FIG. 1 shows a power transmission device for a vehicle having a control device according to an embodiment of the present invention, and shows an electric four-wheel drive system based on a front engine front wheel drive (FF). In the figure, the engine 10 is an internal combustion engine such as a gasoline engine or a diesel engine, and its output torque is a pair of front wheels via a torque converter 12, a transmission 14, a front wheel differential gear device 16, and an axle 18. 20 is transmitted. A generator 24 exclusively for power generation is provided in the engine 10. The engine 10 to the front wheels 20 correspond to the front wheel drive system. This type of vehicle is a four-wheel drive vehicle that does not use a propeller shaft.
[0014]
The output torque of the electric motor / generator (hereinafter referred to as MG) 28 is transmitted to the pair of rear wheels 34 via the rear wheel differential gear device 30 and the axle 32. The MG 28 to the rear wheel 34 correspond to the rear wheel drive system. When the rear wheel 34 is driven by the MG 28, the four-wheel drive state is set. The MG 28 also has a function as a generator (generator) that generates electric power by being rotationally driven by the braking energy of the vehicle and outputs generated electric power (regenerative energy). The generator 24, which may supply power directly to the MG 28 during four-wheel drive, has a power generation capacity with a capacity slightly larger than the capacity of the MG 28.
[0015]
The transmission 14 includes, for example, a constant-mesh type parallel two-shaft manual transmission, and a plurality of gears when elements of a plurality of planetary gear units are selectively connected or stopped by a hydraulic friction engagement device. An automatic transmission that achieves a stage, a belt-type continuously variable transmission in which a transmission belt is wound around a pair of pulleys having a variable effective diameter, and the like.
[0016]
The engine and shift electronic control unit 38 determines the actual engine speed N from the relationship stored in advance._E, Fuel injection control for controlling the fuel injection time based on the intake air amount Q / N or the intake pipe pressure, and the actual engine speed N from the previously stored relationship_EThe ignition timing control for controlling the basic ignition timing based on the intake air amount Q / N, the target idle rotation speed when the engine 10 is idle is determined, and the idle control is performed so that the actual idle rotation becomes the target idle rotation speed. When the transmission 14 is an automatic transmission, for example, when the transmission 14 is an automatic transmission, the actual vehicle speed V and the accelerator opening (accelerator pedal depression amount or throttle valve opening) θ are obtained from a previously stored shift diagram. Based on this, a shift gear stage is determined, and automatic shift control for switching to the shift gear stage is executed.
[0017]
The electronic controller 40 for traction control includes a wheel speed sensor 42 provided on each of the pair of front wheels 20 and the pair of rear wheels 34._FR, 42_FL, 42_RR, 42_RLWheel speed (vehicle speed converted based on wheel rotational speed) V based on the signal from V_FR, V_FL, V_RR, V_RL, Front wheel speed V_F[= (V_FR+ V_FL) / 2], rear wheel speed V_R[= (V_RR+ V_RL) / 2], and vehicle body speed V (for example, wheel speed V_FR, V_FL, V_RR, V_RLIs calculated as the vehicle speed V, that is, the vehicle speed V), while the rear wheel vehicle speed V obtained from the rear wheel 34 not driven by the engine 10, for example, is calculated._RAnd front wheel speed V obtained from the front wheel 20 which is the main drive wheel_FIs a preset control start slip speed ΔV₂If the slip determination of the main drive wheel (front wheel 20) is made by exceeding the traction control, the traction control for increasing the traction force at the start of the vehicle is executed, the slip speed ΔV and the front wheel vehicle speed V_FThe slip ratio R_S[= (ΔV / V_F) × 100%] is a preset target slip ratio range R_S ^*In order to enter, the output of the engine 10 is suppressed using the throttle valve or the fuel injection amount, and at the same time, the rotation of the front wheel 20 is controlled using the front wheel brake 44 to suppress the driving force of the front wheel 20. Since the friction coefficient μ of the wheel with respect to the road surface has a property of changing as shown in FIG. 2, for example, the target slip ratio range R_S ^*Is set in a region where the friction coefficient μ of the wheel is maximum.
[0018]
The motor control electronic control unit 46, for example, as shown in the double line section of FIG. 3, regenerative control for storing the regenerative power output from the MG 28 in the capacitor 48 during vehicle braking, and for example, the thick line of FIG. As shown in the section, the electric power stored in the capacitor 48 in accordance with the accelerator opening θ is converted to the inverter 50 when starting on a high friction coefficient road surface (high μ road) such as a normal road surface or a dry road, or at an acceleration travel time. By supplying the MG28 to the MG28, the driving force of the MG28 is added to the driving force of the engine 10, and the acceleration of the vehicle is assisted (assisted) to increase the fuel efficiency, and the low μ on the frozen road, the snowy road, etc. When starting on a friction coefficient road surface (low μ road), low μ road assist control is executed to increase the starting ability of the vehicle or stop the MG 28 when unnecessary. The output current and drive current of the MG 28, the output current of the generator 24, the storage current and output current of the capacitor 48 are current controlled by the inverter 50 controlled by the motor control electronic control unit 46. is there.
[0019]
The road surface gradient sensor 52 is composed of a G sensor or an inclinometer used at a vehicle speed of approximately zero, and the road surface inclination angle θ_ROADOr gradient (tilt) α (= tan θ_ROAD) Is supplied to the motor control electronic control unit 46 and the like. The engine and shift electronic control device 38, the traction control electronic control device 40, and the motor control electronic control device 46 are so-called microcomputers including a CPU, a ROM, a RAM, an input / output interface, and the like. The input signal is processed according to a program stored in the ROM in advance using the storage function, and the control signal is output. The input signal, the storage signal, and the operation value are exchanged as needed. It has become.
[0020]
FIG. 4 is a functional block diagram mainly illustrating the main part of the control function of the motor control electronic control unit 46. In FIG. 4, a traction control means 60 corresponds to the traction control electronic control unit 40, and a slip of the main drive wheel (front wheel 20) occurs when the vehicle starts using the characteristics shown in FIG. In order to increase the traction force of the front wheel 20 in a state where the road surface friction coefficient μ is low, the slip ratio R_S[= (ΔV / V_F) × 100%] is a preset target slip ratio range R_S ^*In order to enter, the output of the engine 10 is suppressed using the throttle valve or the fuel injection amount, and at the same time, the rotation of the front wheel 20 is suppressed using the front wheel brake 44 and the driving force of the front wheel 20 is suppressed. Note that the traction control by the traction control means 60 is performed even if the vehicle body speed becomes zero._FThe lower limit of the detectable range is, for example, 1 to 2 km / h or more, and is continued.
[0021]
The start operation determination means 62 is, for example, a stop determination vehicle speed V set to about 1 to 2 km / h, which is the lowest vehicle speed at which the vehicle speed V can be detected._x1It is determined that the start operation of the vehicle has been performed based on the increase in the accelerator opening θ when When the start operation of the vehicle is performed, not only the front wheels 20 are driven to rotate by the engine 10, but at the same time, before the low μ road determination is performed, the MG 28 is controlled by the high μ road assist control means 72 described later. By actuating, the rear wheel 34 is rotationally driven to assist the start of the vehicle.
[0022]
The road surface state determination means 64 determines whether the traveling road surface is a high μ road having a high road surface friction coefficient μ based on the slip state of the front wheels 20 that are the main drive wheels when the vehicle start operation is determined. A low μ road having a low road surface friction coefficient μ such as a frozen road or a snowy road is determined. The low μ road determination is performed by, for example, the control start slip speed ΔV in which the slip speed ΔV is set in advance.₂It is based on having exceeded. This is based on the relationship that the road surface friction coefficient μ is smaller as the slip speed ΔV is larger. Since the slip determination condition by the road surface condition determination means 64 is almost the same as the start condition of the traction control means 60, the traction control means 60 suppresses the driving force of the front wheels 20 when the slip determination is performed. Since the control is started, the road surface state determination unit 64 can also be referred to as a driving force reduction state determination unit that determines a state in which the driving force of the front wheels 20 is reduced by the traction control unit 60.
[0023]
The traveling state determination unit 66 is a state in which the road surface state determination unit (driving force reduction state determination unit) 64 determines that the control for suppressing the driving force of the front wheels 20 by the traction control unit 60 has been started. Whether the vehicle speed V is increased, for example, whether or not the four-wheel drive vehicle of this embodiment is expected to be able to travel forward by suppressing the driving force of the front wheels 20 despite the slip. No, that is, currently detected vehicle speed V_{tx + 1}Is the last detected vehicle speed V_txIt is determined based on whether or not it is larger. The prohibiting means 68 is determined to be in a state where the driving force of the front wheels 20 is suppressed by the road surface condition determining means (driving force reducing state determining means) 64, and the traveling state determining means 66 advances the four-wheel drive vehicle forward. When it is determined that the vehicle is in a driving state that is expected to be able to travel, the vehicle drive force assist control operation using the MG 28 by the motor drive control means 70 is prohibited. This is because the vehicle can travel forward without being assisted by the driving force of the MG 28.
[0024]
The motor drive control means 70 is a high μ road assist control means 72 for assisting the acceleration of the vehicle using the driving force of the MG 28, that is, the driving force of the rear wheel 34 which is the auxiliary driving wheel, on a normal road surface having a high friction coefficient μ. When the vehicle starts on a road surface having a low coefficient of friction μ such as a snowy road or a freezing road where traction control is performed by the traction control means 60, a low μ road for assisting the start of the vehicle using the driving force of the MG 28 Assist control means 74 is provided.
[0025]
In the assist control at the start of the vehicle by the high μ road assist control means 72, the MG 28 is driven exclusively by the limited electric power stored in the capacitor 48, and therefore the high μ road assist torque T of the MG 28 is driven._AHIs determined to have a magnitude corresponding to the accelerator opening θ and is corrected according to the road gradient α._AH1Up to, for example, as shown in FIG._AH1Is held for a short time and then lowered at a predetermined gradient. The high-μ road assist control means 72 has a basic assist torque T that increases with an increase in the engine output torque based on the rear load distribution ratio and the engine output torque (accelerator opening θ) from the relationship stored in advance._AHOIn order to obtain the assist driving force corresponding to the road surface gradient (road surface inclination) α and the assist torque correction coefficient K that increases as the road surface gradient α increases, for example, from the relationship shown in FIG.₁And the assist torque correction coefficient K₁Is multiplied by the above basic assist torque T_AHOAssist torque correcting means 73 for correcting the torque to the increasing side. At the time of acceleration operation while the vehicle is running, for example, it is determined from the pre-stored relationship shown in FIG. 16 whether or not the vehicle is in the acceleration willing area based on the actual accelerator opening θ and its change rate dθ / dt. If it is within the will area, the same assist control as described above is performed.
[0026]
In the assist control by the low μ road assist control means 74, the MG 28 is driven exclusively by the electric power stored in the capacitor 48 and the electric power generated by the generator 24. For example, FIG. 6 (a) or FIG. b) Low μ road assist torque T of MG28 as shown in FIG._ALIs the high μ road assist torque value T_AH1Assist torque value T determined to be larger than_AL1The power is stored rapidly in the capacitor 48 until the power supply command is supplied to the MG 28 almost simultaneously, but the power generated by the generator 24 is continued slightly later. As a result, the assist torque to be output by the MG 28 is calculated based on the rear load distribution ratio, the accelerator opening θ, the road surface gradient α, and the road surface friction coefficient μ, which are the vehicle state at the time of starting, so that it is the main driving wheel. Before the front wheel 20 slips, the MG 28 assists with the driving force. Low μ road assist torque T at this time_ALThe broken line indicates the torque corresponding to the electric power supplied from the generator 24, and the area A before the broken line indicates the amount of electric power supplied from the capacitor 48, that is, electric energy, that is, the power generation delay of the generator 24. This corresponds to the shortage of electrical energy. The capacitor 48 has at least a capacity for storing the amount of electric energy that is deficient due to the power generation delay of the generator 24.
[0027]
The low μ road assist control means 74 has a basic assist torque T that increases with an increase in the engine output torque based on the rear load distribution ratio and the engine output torque (accelerator opening θ) from the relationship stored in advance._ALOIn order to obtain an assist driving force corresponding to the road surface gradient (road surface inclination) α, the basic assist torque T increases as the road surface gradient α increases._ALOIn order to suppress slip related to the road surface friction coefficient μ, the basic assist torque T increases as the road surface friction coefficient μ increases._ALOSecond assist torque correcting means 80 for correcting the torque to the decreasing side, and the corrected low μ road assist torque T_ALIs output. For example, the first assist torque correction means 78 calculates the correction coefficient K corresponding to the actual road surface gradient α from the previously stored relationship shown in FIG.₁And its correction coefficient K₁Basic assist torque T_ALOIs corrected by multiplying by. Further, the second assist torque correction means 80 has a correction coefficient K corresponding to the slip rotational speed ΔV that is closely related to the actual road friction coefficient μ from the previously stored relationship shown in FIG.₂And its correction coefficient K₂Basic assist torque T_ALOIs corrected by multiplying by. Eventually, the assist torque T output by the low μ road assist control means 74_ALIs K₁・ K₂・ T_ALOIt becomes. FIG. 9 shows the above relationship.
[0028]
Further, the low μ road assist control means 74 is configured to determine a determination value SOC in which the remaining charge SOC of the capacitor 48 is set in advance during the low μ road assist control period._OControl period remaining charge determination means 82 for determining whether or not it is sufficiently high, and a determination value SOC in which the remaining charge SOC of the capacitor 48 is preset by the control period remaining charge determination means 82._OIn the low μ road assist control, the power stored in the capacitor 48 is quickly supplied to the MG 28 and simultaneously the generated power of the generator 24 is supplied to the MG 28. A cooperative power supply means 84 for rapidly starting up the assist drive of the MG 28 to quickly assist the start of the vehicle, and a determination value SOC in which the remaining charge SOC of the capacitor 48 is preset by the control period remaining charge determination means 82._OWhen it is determined as follows, the power supply switching means 86 for stopping the power supply from the capacitor 48 and supplying power from the generator 24, and whether the road surface is a flat road or not, the road surface gradient α is the flat road determination value α.₀And a flat road judging means 88 for switching to power feeding from the generator 24 by the power source switching means 86 in the low μ road assist control if the road is a flat road. Above judgment value SOC_OIs a value set in advance to determine whether or not there is a remaining charge necessary for rapidly starting up the assist drive of the MG. The power source switching means 86 has a slope α with a flat road determination value α.₀If it becomes smaller than that, not only the amount of power supply from the capacitor 48 is made zero, but also the power supply ratio from the capacitor 48 may be reduced as the road surface gradient α decreases.
[0029]
In the cooperative power supply means 84, the assist torque corresponding to the electric power generated by the generator 24 shown by the broken line in FIG. 6 (a) or FIG. 6 (b) and the assist torque in FIG. 6 (a) or FIG. The power supplied from the capacitor 48 is controlled so as to fill the difference A from the required assist torque indicated by the solid line of FIG. V_FIs increased and the upshift is being executed, the gear stage of the transmission 14 is switched to the low speed side and the engine speed N_EIs raised. When the slip of the front wheel 20 exceeds a certain level, the capacitor 48 is charged with a part of the output of the generator 24 in order to reduce the driving force of the front wheel 20 and the load on the generator 24 is increased. Alternatively, in addition, an auxiliary machine such as an air conditioner is operated to increase the load on the engine 10.
[0030]
The assist control end determination means 90 determines whether the low μ road assist control end condition, for example, the slip speed ΔV is previously controlled by the control start slip speed ΔV.₂Control end slip speed ΔV set lower than₁The accelerator opening θ is set to a value near the minimum value θ_MBelow, vehicle speed V is V_x2Based on the satisfaction of any of the above, the end of the low μ road assist control by the low μ road assist control means 74 is determined.
[0031]
The low μ road assist control end means 92 is a low μ road stable vehicle speed V at which the vehicle speed V is preset._x2The vehicle speed determining means 94 for determining whether or not the vehicle speed is equal to or higher than the above, and the vehicle speed V is set to a low μ road stable vehicle speed V by the vehicle speed determining means 94_x2While it is determined as above, it is provided with assist torque gradually decreasing means 96 for gradually decreasing the assist torque toward zero at a relatively low decreasing speed set in advance, and the accelerator opening θ is Value θ set near the minimum value_MAssist torque T_AThe output of the MG 28 is controlled on the basis of the vehicle speed state when the vehicle speed is gradually decreased. Low μ stable vehicle speed V_x2The vehicle speed is such that the vehicle can stably travel forward even if the front wheel 20 slips slightly, for example, a value of about several to a few dozen km / h.
[0032]
The charge remaining amount determination means 100 at the end of control is a determination value SOC in which the remaining charge SOC of the capacitor 48 is set in advance at the end of the low μ road assist control._OIt is determined whether or not it exists enough to exceed. At the end of control, the capacitor charging means 102 is a determination value SOC in which the remaining charge SOC of the capacitor 48 is set in advance by the remaining charge determination means 100 at the end of control when the low μ road assist control ends._OIf it is determined that it is below, the discharged capacitor 48 is immediately charged by causing the generator 24 to generate power following the low μ road assist control period. For example, the assist torque T on the low μ road shown in FIG._ALAn area B surrounded by a solid line and a broken line corresponds to the electric power supplied from the generator 24 for charging the capacitor 48.
[0033]
The traction correction control means 106 has a predetermined determination vehicle speed V set in advance under the low μ road assist control._TRCOThe traction validity determining means 108 for determining whether or not the traction control by the traction control means 60 is acting effectively based on whether or not the actual vehicle speed V is lower than the actual vehicle speed V, and the traction validity determining means 108 In a situation where it is determined that the control is acting effectively, whether the vehicle speed is increasing or the vehicle speed is stagnant, for example, the currently detected vehicle speed V_{tx + 1}Is the last detected vehicle speed V_txIf the vehicle speed state determination unit 110 determines whether the vehicle speed is greater than the vehicle speed state, and if the vehicle speed state determination unit 110 determines that the vehicle speed is increasing, the traction control is not corrected, but the vehicle speed is in a stagnation state. If determined, the driving force of the front wheels 20 suppressed by the traction control is relaxed by relaxing the braking force of the front wheel brake 44, relaxing the restriction on the fuel injection amount to the engine 10, and relaxing the ignition timing retardation. If the driving force suppression mitigating means 112 and the traction validity determining means 108 determine that the traction control is working effectively, the driving force of the front wheels 20 suppressed by the traction control is further suppressed. Driving force suppression strengthening means 114 for shifting the slip ratio to a lower side, and driving force suppression strengthening means 114 That the slip ratio of the front wheel 20 after the suppression of the driving force of the front wheels 20 R_SIs the target slip ratio R_S ^*A slip duration determining means 116 for determining whether or not a slip state greater than a predetermined time has been exceeded, and when the slip duration determining means 116 determines that the slip state of the front wheels 20 has been maintained for a predetermined time or longer. For example, the operation of an auxiliary machine such as an air conditioner, the upshift of the transmission 14, and the brake that fixes the reaction force member of the shift stage different from the current shift stage are slightly slipped to brake against the driving force. Engine load increasing means 118 for increasing the load of the engine 10 by using the operation to increase the power generation amount of the generator 24 and the like.
[0034]
FIG. 10 is a flowchart for explaining a main part of the control operation of the motor control electronic control unit 46. In the main routine of FIG. 10, at step (hereinafter, step is omitted) M1, it is determined whether or not the content of the flag F1 is “1”. The flag F1 indicates that the low μ road assist control routine is being executed when the content is “1”. If the determination of M1 is affirmed, M9 and subsequent steps are executed. However, since the determination of M1 is initially denied, M2 and M3 corresponding to the start operation determination unit 62 are executed. In this M2, the stoppage determination vehicle speed V set in advance to about 1 to 2 km / h, which is the lowest vehicle speed at which the vehicle speed V can be detected._x1It is determined whether or not it is below, and in M3, it is determined whether or not the accelerator opening θ is increased._{tx + 1}Is the previously detected accelerator opening θ_txIt is judged based on whether it is larger than.
[0035]
If both the determinations of M2 and M3 are affirmed, in M4 corresponding to the road surface state determination means 64, the road surface state, that is, a normal high μ road having a large friction coefficient μ, or a frozen road, a snowy road, etc. The determination as to whether the road is a low μ road having a small friction coefficient μ is, for example, the front wheel speed V_FAnd rear wheel speed V_RThe slip speed ΔV, which is the difference from the₂It is performed based on whether or not it is larger. If the main drive wheel (front wheel 20) has not yet slipped at least immediately after the start operation of the vehicle, it is determined as a high μ road in M4, so the high μ road assist control in M5 is once executed. Thus, the front wheel 20 and the rear wheel 34 are rotationally driven. Under such circumstances, since the slip speed ΔV has a property closely related to the road surface friction coefficient μ, for example, the slip speed ΔV is determined based on the determination reference value ΔV.₂If it is larger than that, it is determined that the road is a low μ road, and the slip speed ΔV is determined to be the reference value ΔV₂If it is smaller than that, it is determined that the road is a high μ road.
[0036]
If the determination of either M2 or M3 is negative, or if it is determined in M4 that the road is a high μ road, the high μ road assist control routine of M5 corresponding to the high μ road assist control means 72 is performed. Is executed. FIG. 11 shows the high μ road assist control routine. In M5-1 of FIG. 11, it is determined based on a signal from the road surface gradient sensor 52 whether or not the road surface on which the vehicle is going to travel is inclined. If the determination of M5-1 is negative, since the road is flat, first, in M5-2, whether or not the driver intends to accelerate is determined based on the accelerator pedal operation, for example, the accelerator opening θ is relatively small. The determination is made based on whether or not the set determination reference value is exceeded, or whether or not the rate of change dθ / dt of the accelerator opening θ exceeds a preliminarily set determination reference value.
[0037]
If the determination in M5-2 is negative, there is no acceleration intention, so M5-3 is not executed. If the determination is positive, the acceleration is in the acceleration intention, so the basic assist torque calculation means 71 M5-3 corresponding to is executed. In this M5-3, for example, the actual accelerator opening θ and the rearward load distribution ratio increase as the rear load distribution ratio increases, and from the pre-stored relationship shown in FIG. 12 (a) and / or FIG. 12 (b), for example. Based on the accelerator opening change rate dθ / dt, the basic assist torque T is increased so that the accelerator opening θ and / or the accelerator opening change rate dθ / dt increases._AHOIs calculated and its basic assist torque T_AHOIs high μ road assist torque T_AHBy driving the MG 28 so as to obtain it, the high μ road assist control on the flat road is executed. Next, at M5-4, the remaining charge of the capacitor 48 prepared in advance for the high μ road assist control falls below a predetermined amount, and at the same time, the high μ road assist control is terminated.
[0038]
If the determination of M5-1 is affirmative, the road is an inclined road, and therefore, in M5-5 corresponding to the assist torque correction means 73, for example, the road surface gradient α detected by the road surface gradient sensor 52 from the relationship shown in FIG. As the road surface gradient α increases, the assist torque T_AHFor correcting to increase the value, that is, the correction coefficient K₁Is determined. Next, in M5-6, whether or not there is an intention to accelerate is determined in the same manner as in M5-2, and if there is an intention to accelerate, in M5-7 corresponding to the basic assist torque calculating means 71, the above M5-3 Basic assist torque T_AHOAnd the correction coefficient K₁Correction calculation is performed by the high μ road assist torque T_AH(= K₁・ T_AHO) Is determined, and the MG 28 is driven so as to obtain it, thereby executing high μ road assist control on a slope. Next, at M5-4, the remaining charge of the capacitor 48 prepared in advance for the high μ road assist control falls below a predetermined amount, and at the same time, the high μ road assist control is terminated.
[0039]
Returning to FIG. 10, when it is determined in M4 that the road is a low μ road, the road surface of the vehicle is in a state of being easily slipped such as an icy road or a snowy road, so M6 corresponding to the running state determination unit 66 is obtained. In this embodiment, whether or not the four-wheel drive vehicle according to the present embodiment is in a traveling state that is expected to be able to travel forward is determined whether or not the vehicle speed V is increasing, that is, the vehicle speed V detected this time_{tx + 1}Is the last detected vehicle speed V_txIt is judged based on whether it is larger than. If the determination at M6 is affirmative, the rear wheel 34 is driven by the MG 28 by the high μ road assist control executed immediately after the start operation, so that the vehicle can travel forward on the low μ road as it is. Therefore, in M7 corresponding to the prohibiting means 68, the assist driving by the MG 28 is prohibited and this routine is terminated. Thereby, the consumption of electrical energy is reduced.
[0040]
However, if the determination in M6 is negative, that is, if it is difficult to advance the vehicle on a low μ road, an M8 low μ road assist control routine corresponding to the low μ road assist control means 74 is executed. . This low μ road assist control routine is, for example, shown in FIG. In M8-1 in FIG. 13, the road surface gradient α is read based on the detection signal of the road surface gradient sensor 52, and the road surface friction coefficient μ is read. This road surface friction coefficient μ is the slip ratio R used in the traction control means 60._SOr calculated based on the slip speed ΔV. Slip rate R_SThis is because the slip speed ΔV has a property closely related to the road surface friction coefficient μ.
[0041]
Next, in M8-2 corresponding to the basic assist torque calculating means 76, for example, the actual accelerator opening θ and / or from the relationship stored in advance as shown in FIG. 12 (a) and / or FIG. 12 (b). Based on the accelerator opening change rate dθ / dt, the basic assist torque T is increased so that the accelerator opening θ and / or the accelerator opening change rate dθ / dt increases._ALOIs calculated. Subsequently, in M8-3 corresponding to the first assist torque correction means 78 and the second assist torque correction means 80, the first correction coefficient is calculated based on the actual road surface gradient α from the relationship stored in advance as shown in FIG. K₁For example, based on the actual road friction coefficient μ from the relationship shown in FIG.₂And the first correction coefficient K₁And the second correction coefficient K₂Basic assist torque T_ALOLow μ road assist torque T by multiplying and correcting_ALIs calculated. FIG. 9 shows the low μ road assist torque T calculated as described above._ALThe change tendency with respect to the road surface gradient α and the road surface friction coefficient μ is shown.
[0042]
Subsequently, in M8-4 corresponding to the flat road determination means 88, the flat road determination value α in which the road surface gradient α is preset.₀Or less is determined. If the determination of M8-4 is affirmative, it is not necessary to rapidly increase the assist torque of the MG 28 because the road is flat, so that the assist torque output from the capacitor 48 and the power from the generator 24 Cooperation control with the output of the assist torque is prohibited, and in M8-7 corresponding to the power supply switching means 86, switching to low μ road assist control by power from the generator 24 is performed, and the low μ calculated in M8-3 is selected. Road assist torque T_ALIs output.
[0043]
However, if the determination in M8-4 is negative, there is a road slope, so that the remaining charge SOC of the capacitor 48 is preset in M8-5 corresponding to the control period remaining charge determination means 82. Judgment value SOC_OIt is judged whether it is larger. When the determination of M8-5 is affirmed, in M8-6 corresponding to the cooperative power supply unit 84, the power stored in the capacitor 48 is quickly supplied to the MG 28 and at the same time the generated power of the generator 24 is As shown in FIG. 6 (a) or 6 (b), the assist drive of the MG 28 is rapidly started to quickly start the vehicle, and the driving force of the vehicle increases in a timely manner. Thus, the vehicle's ability to move forward is maintained. When the electric power stored in the capacitor 48 is consumed by this cooperative power supply, the determination of M8-5 is denied, so in M8-7, the low μ road assist control using only the electric power from the generator 24 continues thereafter. Is done.
[0044]
Returning to FIG. 10, when the low μ road assist control is executed as described above, M9, M10, and M11 corresponding to the assist control end determination means 90 are executed. In M9, the end determination value ΔV in which the slip speed ΔV is set in advance is set.₁Or less is determined. Further, at M10, the vehicle speed V is a preset low-μ road safety vehicle speed V._x2It is determined whether or not this is the case. In M11, whether the accelerator opening θ is fully closed, that is, its minimum value θ_minIt is determined whether or not.
[0045]
When the determinations of M9, M10, and M11 are all negative, the low μ road assist control is continued. Therefore, after the content of the flag F1 is set to “1” in M12, the steps after M1 are repeated. It is. However, when the determination of either M9 or M10 is affirmed, the assist control end routine of M13 corresponding to the low μ road assist control end means 92 is executed, but the determination of M11 is affirmed. In this case, M14 and subsequent steps after the assist control end routine of M13 are executed.
[0046]
The M13 assist control end routine is, for example, shown in FIG. In FIG. 14, in M13-1 corresponding to the assist torque gradual decrease means 96, the low μ road assist torque T by the MG28._ALIs gradually reduced at a relatively low predetermined reduction rate. Next, in M13-2 corresponding to the vehicle speed determination means 94, the vehicle speed V is set in advance at a low μ road stable vehicle speed V._x2It is determined whether or not this is the case. If the determination of M13-2 is negative, the low μ road assist torque T_ALIf this is reduced, it will affect the forward travel of the vehicle. For example, M8 or less is executed, and the low μ road assist control is started again. However, if the determination in M13-2 is affirmed, the low μ road assist torque T is determined in M13-3._ALIt is determined whether or not has reached zero. Since the determination of M13-3 is initially denied, the above M13-1 and subsequent steps are repeatedly executed. As a result, the low μ road assist torque T_ALLow μ stable vehicle speed V that does not affect the forward travel of the vehicle even if the vehicle is reduced_x2When the vehicle speed is V or higher, the low μ road assist torque T_ALIs continuously reduced toward zero.
[0047]
Returning to FIG. 10, next, in M14 corresponding to the control remaining charge remaining amount determining means 100, the remaining charge SOC of the capacitor 48 is a predetermined determination value SOC._OIt is judged whether it is larger. If the determination of M14 is affirmed, charging of the capacitor 48 with the electric power from the generator 24 is stopped. If not, the generator 24 is prepared for the start of the next low μ road assist control. The capacitor 48 is charged by the electric power from. Low μ road assist torque T shown in Fig. 6 (b)_ALThe section immediately after the falling edge indicates this state. As a result, even when the low μ road assist control is started when the vehicle stops once again due to slip after the vehicle has started by the low μ road assist control at the time of starting uphill road, the low μ road assist torque T is immediately started._ALCan be launched.
[0048]
FIG. 15 corresponds to the traction correction control means 106, and in the situation where the traction control by the traction control means 60 and the low μ road assist control by the low μ road assist control means 74 are being executed. The traction correction control routine executed to correct the control is shown. In FIG. 15, at TA1 corresponding to the traction validity determination means 108, the traction validity determination vehicle speed V at which the vehicle speed V is preset is shown._TRCOIt is determined whether or not the value is lower than. This traction validity determination vehicle speed V_TRCOIs a value for determining that the traction control by the traction control means 60 is acting effectively, that is, the friction coefficient of the front wheel 20 on the low μ road is increased as shown in FIG. This is a value for determining that the vehicle speed V is increasing as a result of contributing to the forward movement of the vehicle, and is a value obtained experimentally in advance.
[0049]
When the determination of TA1 is negative, that is, when it is determined that the traction control of the traction control means 60 is working effectively, the vehicle speed V increases at TA2 corresponding to the vehicle speed state determination means 110. For example, whether the vehicle speed V is currently detected_{tx + 1}Is the last detected vehicle speed V_txJudgment is made based on whether it is larger. If the determination of TA2 is affirmed, the traction control is effective and the vehicle speed V is increasing, so TA3 for correcting the traction control is not executed.
[0050]
However, if the determination of TA2 is negative, that is, the traction validity determination vehicle speed V for determining that the traction control is acting effectively._TRCOIf the vehicle speed V has reached the vehicle speed V but has not increased further and the vehicle speed V is stagnant, the traction control by the traction control means 60 is performed at TA3 corresponding to the driving force suppression / relaxation means 112. The suppression of the driving force for the front wheel 20 is corrected to the mitigation side. For example, the braking force of the front wheel brake 44 that has been increased by the traction control means 60 is corrected to the mitigation side than before. Thereby, the driving torque of the front wheels 20 is recovered, and the vehicle speed V is increased in cooperation with the effect of the low μ road assist control. Next, at TA4, it is determined whether or not the low μ road assist control by the low μ road assist control means 74 is finished. If the determination of TA4 is negative, this routine is terminated without executing TA5, and thus the driving force suppression / relaxation correction for the front wheels 20 is continued. If the determination at TA4 is affirmative, at TA5, normal traction control is restored.
[0051]
If the determination of TA1 is affirmative, that is, if the traction control by the traction control means 60 is not acting effectively at an extremely low vehicle speed, the traction control means 60 in TA6 corresponding to the driving force suppression strengthening means 114. The suppression of the driving force for the front wheels 20 by the traction control is corrected to the predetermined value enhancement side. For example, the braking force of the front wheel brake 44 that has been increased by the traction control means 60 is corrected to a predetermined value strengthening side than before. As a result, the vehicle speed V is obtained by traction control despite the execution of the low μ road assist control._TRCOWhen the vehicle speed is very low, such as immediately after starting, when the vehicle is not able to obtain the predetermined value, a predetermined amount of driving torque for the front wheels 20 is secured and the traction control is validated.
[0052]
Next, in TA7 corresponding to the slip duration determining means 116, the braking force of the front wheel brake 44, which has been increased by traction control in TA6, is corrected to the stronger side than before, but the main driving wheel It is determined whether or not the slip of a certain front wheel 20 has continued for a predetermined time or more. If the determination of TA7 is negative, since the effect of correcting the braking force of the front wheel brake 44 of TA6 has been generated, TA4 and subsequent steps are executed. However, if the determination of TA7 is affirmative, the effect of enhancing the braking force of the front wheel brake 44 of TA6 does not appear, so in TA8 corresponding to the engine load increasing means 118, an air conditioner, etc. Actuating the auxiliary machine, shifting up the transmission 14, and engaging the brake for fixing the reaction force member of the shift stage different from the current shift stage slightly to slip against the driving force, By increasing the power generation amount of the generator 24 and increasing the load of the engine 10, the slip of the front wheels 20 is further suppressed and the forward force is increased.
[0053]
As described above, according to this embodiment, in addition to the generator (generator) 24 that is rotationally driven by the engine 10 to supply electric energy to the MG 28, the capacitor (power storage device) 48 is provided, and the vehicle When the MG 28 is driven to assist the traction force at the time of starting, the electric power from the generator 24 and the electric energy from the capacitor 48 are simultaneously supplied to the MG 28 by the cooperative power supply means 84 (M8-6). Therefore, the drive torque of the MG 28 rises rapidly, so that the delay of the assist drive of the MG 28 due to the power generation delay of the generator 24 driven by the engine 10 is preferably prevented, and the drive by the engine 10 is started when the vehicle starts. The slip of the main drive wheel (front wheel 20) to be performed is suitably suppressed.
[0054]
In the present embodiment, the capacitor 48 stores electrical energy by polarization of the dielectric, and stores the amount of electrical energy that is insufficient due to the power generation delay of the generator 24 in order to quickly raise the output torque from the MG 28. Since the electrical energy stored in the capacitor 48 is output more rapidly than when using a battery that electrochemically stores electrical energy, the drive torque of the MG 28 is further increased. It can be prompt.
[0055]
In this embodiment, the road surface gradient sensor (gradient detection device) 52 that detects the gradient α of the traveling road surface of the front and rear wheel drive vehicle and the capacitor 48 to the MG 28 according to the gradient α detected by the road surface gradient sensor 52. Power supply switching means 86 (M8-7) for switching the ratio of the amount of electric energy supplied to the MG 28 is provided, so that the amount of electric energy supplied from the capacitor 48 to the MG 28 in accordance with the road surface gradient α, ie, The ratio of the power supply amount is switched. For example, as the gradient becomes smaller, the ratio of the amount of electric energy supplied from the capacitor 48 to the MG 28 is reduced, so that the consumption of the electric energy stored in the capacitor 48 is reduced.
[0056]
Further, in the present embodiment, immediately after the end of the assist drive of the MG 28, the control charging capacitor 102 (M15) at the end of control for storing the capacitor 48 by the power generation of the generator 24 based on the storage amount SOC of the capacitor 48 is provided. When the driving of the MG 28 is repeatedly performed on the low μ road, there is an advantage that the driving torque of the next MG 28 rises rapidly.
[0057]
Further, in the present embodiment, when the assist driving of the MG 28 is executed, it is a period in which the traction force of the front wheel 20 is insufficient due to the occurrence of the slip of the front wheel 20 driven by the engine 10, and the assist driving of the MG 28 is performed. Regardless of the situation, if the forward / rear wheel drive vehicle cannot move forward, the load on the auxiliary machine of the engine 10 is maximized, the transmission gear stage of the transmission is increased, and the friction engagement devices in the transmission are overlapped. The engine load increasing means 118 (TA8) for further reducing the driving force of the front wheels 20 driven by the engine 10 by executing at least one of the control is included, so that the engine 10 is driven when the vehicle starts. When the front wheel 20 is slipped, the load on the engine 10 is increased and the front wheel 20 driven by the engine is driven. Because the lip is suppressed, the traction force of the vehicle is enhanced.
[0058]
As mentioned above, although one Example of this invention was described based on drawing, this invention can be applied also in another aspect.
[0059]
For example, in the above-described embodiment, a so-called electric four-wheel drive vehicle based on front engine front wheel drive (FF) is used, but so-called electric based on front engine rear wheel drive (FR) is used. A four-wheel drive vehicle may be used.
[0060]
In the above-described embodiment, the capacitor 48 that electrostatically stores electric energy by the polarization of the dielectric is used. However, it may be a power storage device such as a storage battery that electrochemically stores electric energy. Electric power can be supplied to the MG 28 more quickly than the generator 24 to quickly raise the assist torque.
[0061]
The generator 24 of the above-described embodiment is used exclusively as a generator. However, the generator 24 may be operated as a motor that starts the engine 10 and a motor that outputs driving torque when the vehicle starts. Further, the generator 24 may be connected so as to rotationally drive auxiliary equipment such as an air conditioner compressor and a power steering oil pump while the engine 10 is stopped when the vehicle is stopped.
[0062]
Further, the cooperative power supply means 84 of the above-described embodiment performs power supply from the generator 24 at the same time as power supply from the capacitor 48, but these power supply may not be completely simultaneous, and there is a slight time difference. It can be present.
[0063]
Further, in FIG. 10 of the above-described embodiment, when the determination of M1 is affirmed, M9 or less is executed, but M8 or less may be executed.
[0064]
The above description is only an example of the present invention, and the present invention can be variously modified without departing from the gist of the present invention.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating the configuration of a control device according to an embodiment of the present invention and a power transmission device of a four-wheel drive vehicle to which the control device is applied.
2 is a diagram for explaining the operation of the electronic controller for traction control in FIG. 1. FIG.
3 is a diagram illustrating the operation of an electric motor controlled by the motor control electronic control device of FIG. 1, wherein a thick line indicates an assist torque generation period of the electric motor, and a double line indicates a regeneration period of the electric motor. Yes.
4 is a functional block diagram illustrating a main part of a control function of the motor control electronic control device of FIG. 1; FIG.
FIG. 5 is a diagram for explaining a control operation by the high μ road assist control means in FIG. 4;
6A and 6B are diagrams for explaining the control operation by the low μ road assist control means in FIG. 4, where FIG. 6A shows a case where charging by MG is not performed, and FIG. 6B shows a case where charging by MG is performed. Yes.
7 is a diagram showing a relationship used in first assist control means included in the low μ road assist control means in FIG. 4; FIG.
8 is a diagram showing a relationship used in second assist control means included in the low μ road assist control means in FIG. 4. FIG.
9 is a diagram showing the relationship between the low μ road assist torque output from the electric motor by the low μ road assist control means of FIG. 4, the road surface gradient α, and the road surface friction coefficient μ. FIG.
FIG. 10 is a flowchart illustrating a main routine for assist control, which is a main part of the control operation of the electronic control device for motor control of FIG. 1;
FIG. 11 is a diagram for explaining in detail the high μ road assist control routine of FIG. 10;
FIG. 12 is a diagram showing a relationship used to determine the basic assist torque in FIG. 11, wherein (a) shows the relationship for determining based on the accelerator opening θ, and (b) shows the accelerator opening. The relationship for determining based on degree change rate d (theta) / dt is shown.
FIG. 13 is a diagram for explaining in detail the low μ road assist control routine of FIG. 10;
FIG. 14 is a diagram for explaining in detail the low μ road assist control end routine of FIG. 10;
15 is a flowchart for explaining a traction correction control routine, which is a main part of the control operation of the motor control electronic control device of FIG. 1; FIG.
FIG. 16 is a diagram showing a relationship used to determine whether or not to perform assist by MG at the time of acceleration operation while the vehicle is running.
[Explanation of symbols]
10: Engine
20: Front wheel (drive wheel)
28: Electric motor
48: Capacitor (power storage device)
52: Road surface gradient sensor (gradient detection device)
84: Cooperative power supply means
86: Power source switching means
102: Capacitor charging means at the end of control (charging means at the end of control)

Claims (6)

A generator driven by an engine; and an electric motor driven by the generator, wherein one of a front wheel drive system and a rear wheel drive system is the engine as a drive source, and the other is the electric motor as a drive source. A control device for a front and rear wheel drive vehicle of the type
A power storage device;
When driving the electric motor, it is determined whether or not the electric motor needs to be started up rapidly. When it is necessary to start up the electric motor, the electric energy from the generator and the electric energy from the power storage device A control device for a front-and-rear wheel drive vehicle, comprising: coordinated power supply means for simultaneously supplying the electric motor to the electric motor. 2. The control of a front and rear wheel drive vehicle according to claim 1, further comprising flat road determination means for determining whether or not the electric motor needs to be rapidly started up based on a traveling road surface gradient of the front and rear wheel drive vehicle. apparatus. The power storage device is a capacitor that stores electrical energy by polarization of a dielectric, and has a capacity to store an amount of electrical energy that is insufficient due to a power generation delay of a generator in order to quickly start up output torque from the electric motor. The control device for a front and rear wheel drive vehicle according to claim 1 or 2 . A gradient detecting device for detecting the gradient of the traveling road surface of the front and rear wheel drive vehicle;
Depending on the gradient detected by the gradient detecting device, from the electrical storage device wherein the power supply switching means for switching the ratio of the supply amount of electrical energy supplied to the electric motor, according to claim 1 to 3 is intended to include any of the Control device for front and rear wheel drive vehicle. The control end charging means for storing power in the power storage device by the power generation by the power generator based on the amount of power stored in the power storage device immediately after the driving of the electric motor is completed, before and after any one of claims 1 to 4 Control device for wheel drive vehicle. The driving of the electric motor is executed during a period in which the traction force of the driving wheel is insufficient due to the occurrence of slip of the driving wheel driven by the engine, and the front and rear wheels are driven regardless of the driving of the electric motor. If the forward drive of the drive vehicle cannot be obtained, at least one of maximizing the load on the engine auxiliary machine, increasing the speed of the transmission gear stage, and overlapping engagement of friction engagement devices in the transmission. one of the running control the control device of any of the front and rear wheel drive vehicle according to claim 1 to 5 in which an engine load increasing means for further reducing the driving force of the driving wheels driven by the engine.

Images