JP4162471B2 - Drive control device for front and rear wheel drive vehicles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drive control device for a front and rear wheel drive vehicle in which one of front wheels and rear wheels can be driven by an engine, and the other wheel can be driven by an electric motor.
[0002]
[Prior art]
In a front-and-rear wheel drive vehicle of the type in which a front wheel is driven by a hybrid drive mechanism including an engine that operates by combustion of fuel and a first motor generator, and a rear wheel is driven by a second motor generator that functions as an electric motor. In addition to driving the front wheels at the time of starting acceleration, etc., there is a front and rear wheel drive vehicle control device that sets the rear wheel drive ratio by the second motor generator to be increased and operates the engine as necessary. Are known. For example, the control device for a front and rear wheel drive vehicle described in Patent Document 1 is this. According to such a front-rear wheel drive vehicle control device, the conventional front-rear wheel drive vehicle control device described above is used when traveling on a road surface with a low friction coefficient such as a snowy road or a frozen road, or when traveling on a slope. When front and rear wheel drive is required, the front and rear wheel drive torque is determined according to the load distribution ratio of the front and rear wheels, and the engine and the first motor generator are controlled so that the determined front wheel drive torque is output. The second motor generator is driven so that the determined rear wheel driving torque is output.
[0003]
[Patent Document 1]
JP 2001-186603 A
[Patent Document 2]
JP 2002-067723 A
[Patent Document 2]
JP 2001-234774 A
[Patent Document 3]
JP-A-9-002090
[Patent Document 4]
Japanese Patent Laid-Open No. 9-240301
[0004]
[Problems to be solved by the invention]
However, for example, when traveling on a slope, when the front and rear wheels are driven as described above, the second motor generator consumes a large amount of power and the amount of power taken out from the power storage device increases. Due to the limited capacity, the continuous running distance in the front and rear wheel drive state may not be sufficiently obtained in the same way as when driving on a road surface with a low road surface friction coefficient, even though the road surface friction coefficient is high. .
[0005]
The present invention has been made against the background of the above circumstances, and the object of the present invention is to provide a drive control device for a front and rear wheel drive vehicle that can obtain a longer travel distance in the front and rear wheel drive state, particularly when traveling on a slope. It is to provide.
[0006]
As a result of various investigations to solve the above problems, the present inventor has found that the conventional front and rear wheel drive traveling is necessary even before and after the front and rear wheel drive traveling until the wheels slip. It has been found that there is no problem in traveling even if the front and rear wheels are not driven completely based on the wheel load distribution ratio. The present invention has been made based on such knowledge.
[0007]
[First Means for Solving the Problems]
  That is, the gist of the first invention is a drive control device for a front and rear wheel drive vehicle in which one of the front wheels and the rear wheels can be driven by an engine and the other wheel can be driven by an electric motor. (A) A motor that calculates a first output torque to be output from the electric motor that drives the other wheel based on the driver's required torque and the torque distribution ratio of the front and rear wheels for front and rear wheel drive Torque calculating means; (b) slip determining means for determining the occurrence of slip on the one wheel; and (c) until the occurrence of slip on the one wheel is determined by the slip determining means. After limiting the torque output from the electric motor that drives the wheels so as not to exceed a predetermined torque limit value, after the occurrence of slippage of the one wheel is determinedCancel the torque limit valueAnd a motor torque limiting means.
[0008]
[Effect of the first invention]
  In this way, the torque output from the electric motor that drives the other wheel by the motor torque limiting means is the predetermined torque limit until the slip determination means determines the occurrence of slipping of the one wheel. After it is limited not to exceed the value and the occurrence of slippage on one of the wheels is determined,The torque limit value is eliminatedTherefore, the traveling distance in the front and rear wheel drive state can be obtained even when traveling on a slope.
[0009]
[Other aspects of the first invention]
  Here, preferably, the motor torque limiting means outputs the torque output from the electric motor that drives the other wheel when the traveling path of the vehicle is a slope.The specified torque limit value is not exceededAs such, it is limited. In this way, the traveling distance in the front-rear wheel drive state when traveling on a slope can be further increased, and when the vehicle travel path is not a slope, for example, according to the front-rear wheel drive request corresponding to the decrease in the road surface friction coefficient.in frontA normal front and rear wheel drive state using the first output torque can be obtained.
[0010]
Preferably, the engine and the motor are operated in an operation mode determined according to a vehicle state from a plurality of operation modes, the engine operating by fuel combustion and a motor generator operating as a generator and an electric motor. The one wheel is rotationally driven by a hybrid drive device that operates a generator. In this way, since the electric power is supplied to the power storage device or the electric motor by the electric power generated by the motor generator that is rotationally driven by the engine, the traveling distance in the front-rear wheel driving state when traveling on a slope can be further increased.
[0011]
  Preferably, the motor generator of the hybrid drive device has a lower power generation capability when the vehicle is traveling backward than when traveling forward, and the motor torque limiting means is the vehicle traveling backward. Sometimes the torque output from the electric motor that drives the other wheel,The specified torque limit value is not exceededAs such, it is limited. In this way, in the backward traveling where the motor generator has a lower power generation capacity compared to the forward traveling, the traveling distance in the front and rear wheel driving state during the slope traveling can be further increased.
[0012]
[Second means for solving the problem]
  Further, the gist of the second invention for solving the above-mentioned problem is that the front wheel and the rear wheel can be driven by an engine, and the other wheel can be driven by an electric motor. A drive control device for a vehicle, comprising: (a) a first motor to be output from an electric motor that drives the other wheel based on a driver's required torque and a front-rear wheel torque distribution ratio for front-rear wheel drive; Motor torque calculation means for calculating one output torque, and (b) torque output from the electric motor that drives the other wheel when the vehicle is traveling backward.The specified torque limit value is not exceededAnd a motor torque limiting means that preferentially uses the torque of the one wheel.
[0013]
[Effect of the second invention]
  In this way, when the vehicle is traveling backwards,Since the torque output from the electric motor that drives the other wheel is limited by the motor torque limiting means so as not to exceed a predetermined torque limit value, the torque of the one wheel is used preferentially, The traveling distance in the front-rear wheel driving state when traveling on a slope can be further increased.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0015]
FIG. 1 is a skeleton diagram illustrating the configuration of a power transmission device for a front and rear wheel drive vehicle, that is, a four wheel drive vehicle, which is a hybrid vehicle to which a drive control device of an embodiment of the present invention is applied. In this four-wheel drive vehicle, a front wheel system is driven by a first drive device having a first prime mover, that is, a main drive device 10, and a rear wheel system is driven by a second drive device having a second prime mover, that is, a sub drive device 12. It is a vehicle of the type which drives.
[0016]
The main drive unit 10 functions as a hybrid drive unit, and selectively functions as an engine 14 that is an internal combustion engine that is operated by burning a mixture of air and fuel, and an electric motor and generator. Motor generator (hereinafter referred to as MG) 16, a double pinion type planetary gear device 18, and a continuously variable transmission 20 whose gear ratio is continuously changed. The engine 14 functions as a first prime mover, that is, a main prime mover, and the MG 16 also functions as a prime mover that is a drive source of the vehicle. The engine 14 has a throttle valve opening θ that controls the amount of intake air in the intake pipe._THIs provided with a throttle actuator 21 for driving the throttle valve.
[0017]
The planetary gear unit 18 is a combining / distributing mechanism that mechanically combines or distributes force, and includes three rotating elements provided so as to be independently rotatable around a common axis, that is, a damper to the engine 14. A sun gear 24 connected via the device 22, a carrier 28 connected to the input shaft 26 of the continuously variable transmission 20 via the first clutch C1 and to the output shaft of the MG 16, and a second clutch C2. And a ring gear 32 that is connected to the input shaft 26 of the continuously variable transmission 20 and connected to a non-rotating member such as the housing 30 via the brake B1. The carrier 28 supports a pair of pinions (planetary gears) 34 and 36 which mesh with the sun gear 24 and the ring gear 32 and mesh with each other so as to be able to rotate. The first clutch C1, the second clutch C2, and the brake B1 are hydraulically engaged when a plurality of overlapping friction plates are pressed by a hydraulic actuator or released by releasing the pressure. This is a friction engagement device.
[0018]
The MG 16 connected to the planetary gear unit 18 and its carrier 28 controls the power generation amount of the MG 16 in the operating state of the engine 14, that is, the rotational state of the sun gear 24, that is, the reaction force that is the rotational driving torque of the MG 16 increases sequentially. As described above, the electric torque converter (ETC) device that smoothly increases the rotation speed of the ring gear 32 and enables smooth start acceleration of the vehicle is configured by being generated in the carrier 28 as described above. At this time, if the gear ratio ρ of the planetary gear unit 18 (the number of teeth of the sun gear 24 / the number of teeth of the ring gear 32) is 0.5, which is a general value, for example, the torque of the ring gear 32: the torque of the carrier 28: the sun gear 24 Torque = 1 / ρ: (1-ρ) / ρ: 1, the torque of the engine 14 is amplified to 1 / ρ times, for example, 2 times, and transmitted to the continuously variable transmission 20. It is called.
[0019]
The continuously variable transmission 20 is wound around a pair of variable pulleys 40 and 42 having variable effective diameters provided on the input shaft 26 and the output shaft 38, respectively, and the pair of variable pulleys 40 and 42. And an endless annular transmission belt 44. The pair of variable pulleys 40 and 42 are input so as to form a V-groove between the fixed rotating bodies 46 and 48 fixed to the input shaft 26 and the output shaft 38, respectively, and the fixed rotating bodies 46 and 48. Movable rotating bodies 50 and 52 that are movable in the axial direction with respect to the shaft 26 and the output shaft 38 and that are not relatively rotatable around the axis, and a variable pulley by applying thrust to the movable rotating bodies 50 and 52 And a pair of hydraulic cylinders 54 and 56 that change the transmission gear ratio γ (= input shaft rotational speed / output shaft rotational speed) by changing the engagement diameter of 40 and 42, that is, the effective diameter.
[0020]
The torque output from the output shaft 38 of the continuously variable transmission 20 is transmitted to the pair of front wheels 66 and 68 via the speed reducer 58, the differential gear device 60, and the pair of axles 62 and 64. It has become. In the present embodiment, a steering device that changes the steering angle of the front wheels 66 and 68 is omitted.
[0021]
The sub-drive device 12 includes a rear motor generator (hereinafter referred to as RMG) 70 that functions as a second prime mover, that is, a sub prime mover, and torque output from the RMG 70 is reduced by a speed reducer 72, a differential gear device 74, and 1 It is transmitted to a pair of rear wheels 80 and 82 via a pair of axles 76 and 78.
[0022]
FIG. 2 is a diagram simply showing the configuration of a hydraulic control circuit for switching the planetary gear unit 18 of the main drive unit 10 to various operation modes. The manual valve 92 mechanically connected to the shift lever 90 that is operated to the P, R, N, D, and B range positions by the driver responds to the operation of the shift lever 90 while using the shuttle valve 93. Then, in the D range, the B range, and the R range, the original pressure output from the oil pump (not shown) is supplied to the first pressure regulating valve 94 that regulates the engagement pressure of the first clutch C1. The original pressure is supplied to the second pressure regulating valve 95 that regulates the engagement pressure of C2, and the original pressure is supplied to the third pressure regulating valve 96 that regulates the engagement pressure of the brake B1 in the N range, the P range, and the R range. The second pressure regulating valve 95 and the third pressure regulating valve 96 control the engagement pressure of the second clutch C2 and the brake B1 in accordance with the output signal from the linear solenoid valve 97 driven by the hybrid control device 104, and the first pressure regulating valve 94. Controls the engagement pressure of the first clutch C <b> 1 according to an output signal from the electromagnetic on-off valve 98 that is a three-way valve that is duty-driven by the hybrid control device 104.
[0023]
FIG. 3 is a diagram illustrating a configuration of a control device provided in the front and rear wheel drive vehicle of the present embodiment. The engine control device 100, the shift control device 102, the hybrid control device 104, the power storage control device 106, and the brake control device 108 are so-called microcomputers having a CPU, a RAM, a ROM, and an input / output interface. While using the storage function, the input signal is processed in accordance with a program stored in advance in the ROM, and various controls are executed. Further, the above control devices are connected so as to be communicable with each other, and when a necessary signal is requested from a predetermined control device, it is appropriately transmitted from the other control device to the predetermined control device. ing.
[0024]
The engine control device 100 executes engine control of the engine 14. For example, a fuel injection valve (not shown) is controlled to control the fuel injection amount, an igniter (not shown) is controlled to control the ignition timing, and the traction control causes the front wheels 66 and 68 that are slipping to grip the road surface. The throttle actuator 21 is controlled in order to temporarily reduce the output.
[0025]
For example, the transmission control device 102 determines the actual transmission ratio γ and the transmission torque, that is, the engine 14 and the MG 16 from the relationship set in advance so that the tension of the transmission belt 44 of the continuously variable transmission 20 becomes a necessary and sufficient value. Based on the output torque, the pressure regulating valve that regulates the belt tension pressure is controlled so that the tension of the transmission belt 44 is set to an optimum value, and the engine 14 is operated in advance along the minimum fuel consumption rate curve or the optimum curve. From the stored relationship, the actual vehicle speed V and the engine load, for example, the throttle valve opening θ expressed as the throttle opening θ_THAlternatively, the target gear ratio γ is based on the accelerator pedal operation amount ACC._mThe actual gear ratio γ is the target gear ratio γ_mThe speed ratio γ of the continuously variable transmission 20 is controlled so as to match the above.
[0026]
Further, the engine control device 100 and the shift control device 102 set the throttle actuator 21 and the fuel injection amount, for example, so that the operating point, that is, the operating point of the engine 14 moves along the best fuel consumption driving line shown in FIG. The speed ratio γ of the continuously variable transmission 20 is changed while being controlled. Further, in response to a command from the hybrid control device 104, the output torque T of the engine 14 is_EOr rotation speed N_ETo change the throttle actuator 21 and the gear ratio γ, the operating point of the engine 14 is moved.
[0027]
The hybrid control device 104 includes an MG control device 116 for controlling an inverter 114 that controls a drive current supplied from the power storage device 112 made of a battery or the like to the MG 16 or a power generation current output from the MG 16 to the power storage device 112. And an RMG control device 120 for controlling an inverter 118 for controlling a drive current supplied from the power storage device 112 to the RMG 70 or a generated current output from the RMG 70 to the power storage device 112, and an operation position P of the shift lever 90_SHBased on the throttle (accelerator) opening θ (the amount of operation ACC of the accelerator pedal 122), the vehicle speed V, and the stored amount SOC of the power storage device 112, for example, one of a plurality of operation modes shown in FIG. And the throttle opening θ and the operation amount B of the brake pedal 124_FOn the basis of the above, a torque regenerative braking mode in which a braking force is generated by a torque necessary for power generation by the MG 16 or RMG 70 or an engine braking mode in which a braking force is generated by a rotational resistance torque of the engine 14 is selected.
[0028]
When the shift lever 90 is operated to the B range or the D range, for example, in a relatively low load start or constant speed travel, the motor travel mode is selected, the first clutch C1 is engaged, and the second clutch C2 and brake are engaged. When B1 is released together, the vehicle is driven exclusively by MG16. In this motor travel mode, when the state of charge SOC of the power storage device 112 falls below a preset lower limit, or when the engine 14 is started to require more driving force. The MG 16 or the RMG 70 is driven while being switched to an ETC mode or a direct connection mode, which will be described later, while maintaining the traveling so far, and the power storage device 112 is charged by the MG 16 or the RMG 70.
[0029]
Further, in the relatively medium load traveling or the high load traveling, the direct connection mode is selected, the first clutch C1 and the second clutch C2 are both engaged, and the brake B1 is released, so that the planetary gear unit 18 is integrated. The vehicle is driven exclusively by the engine 14 or by the engine 14 and the MG 16, or the vehicle is driven exclusively by the engine 14, and at the same time, the power storage device 112 is charged by the MG 16. In this direct connection mode, the rotational speed of the sun gear 24, that is, the engine rotational speed N_E(Rpm) and the rotational speed of the carrier member 28, that is, the rotational speed N of the MG 16_MG(Rpm) and the rotational speed of the ring gear 32, that is, the rotational speed N of the input shaft 26 of the continuously variable transmission 20._INSince (rpm) is the same value, three rotational speed axes (vertical axes), that is, a sun gear rotational speed axis S, a ring gear rotational speed axis R, a carrier rotational speed axis C, and a transmission ratio axis (in a two-dimensional plane) In the collinear diagram of FIG. 6 drawn from (horizontal axis), for example, it is shown by a one-dot chain line. In FIG. 6, the distance between the sun gear rotational speed axis S and the carrier rotational speed axis C corresponds to 1, and the distance between the ring gear rotational speed R and the carrier rotational speed axis C is the gear of the double pinion type planetary gear unit 18. This corresponds to the ratio ρ.
[0030]
Further, for example, in starting acceleration running, the ETC mode, that is, the torque amplification mode is selected, the second clutch C2 is engaged, and both the first clutch C1 and the brake B1 are released, and the amount of power generation (regeneration amount) of the MG 16 That is, the reaction force of MG 16 (driving torque for rotating MG 16) is gradually increased, so that the vehicle is smoothly started to zero while engine 14 is maintained at a predetermined rotational speed. Thus, when the vehicle and MG 16 are driven by the engine 14, if the torque of the engine 14 is 1 / ρ times, for example, ρ = 0.5, it is amplified twice and transmitted to the continuously variable transmission 20. That is, the rotational speed N of MG16_MGIs the point A in FIG. 6 (negative rotation speed, that is, the power generation state), the input shaft rotation speed N of the continuously variable transmission 20 is_INIs zero, the vehicle is stopped, but as shown by the broken line in FIG._MGIs changed to the positive B point, the input shaft rotational speed N of the continuously variable transmission 20 is changed._INIs increased and the vehicle is started.
[0031]
When the shift lever 90 is operated to the N range or the P range, the neutral mode 1 or 2 is basically selected, the first clutch C1, the second clutch C2, and the brake B1 are all released, and the planetary gear unit 18 is released. The power transmission path is released at. In this state, when the storage amount SOC of the power storage device 112 is in an insufficiency state below a preset lower limit value, the charging / engine start mode is set and the brake B1 is engaged. The engine 14 is started by the MG 16. When the shift lever 90 is operated to the R range, for example, in the light load reverse travel, the motor travel mode is selected, the first clutch C1 is engaged, and the second clutch C2 and the brake B1 are both released, The vehicle is driven backward by MG16 exclusively. However, for example, in medium- or high-load reverse travel, the friction travel mode is selected, the first clutch C1 is engaged, the second clutch C2 is released, and the brake B1 is slip-engaged. Thereby, the output torque of the engine 14 is added to the output torque of the MG 16 as a driving force for moving the vehicle backward. In the reverse friction running mode, power generation by MG1 cannot be expected, and the power generation capacity is lower than that in forward running such as the ETC mode.
[0032]
Further, the hybrid control device 104 controls the RMG 70 according to a predetermined driving force distribution ratio in order to temporarily increase the driving force of the vehicle when the vehicle starts or suddenly accelerates according to the driving force of the front wheels 66 and 68. The start ability of the vehicle is increased when the vehicle starts driving on a high-μ road assist control that activates and generates driving force from the rear wheels 80 and 82, and on a low friction coefficient road (low μ road) such as a frozen road or a snowy road. In order to increase the speed, the rear wheels 80 and 82 are driven by the RMG 70, and at the same time, for example, the low μ road assist control is performed to reduce the driving force of the front wheels 66 and 68 by lowering the speed ratio γ of the continuously variable transmission 20.
[0033]
The power storage control device 106 is a lower limit SOC in which a power storage amount SOC of the power storage device 112 such as a battery or a capacitor is set in advance._DIf the power storage device 112 falls below the value, the power storage device 112 is charged or stored with the electric energy generated by the MG 16 or the RMG 70, but the storage amount SOC is set to a preset upper limit value SOC._UIs exceeded, charging with electric energy from the MG 16 or RMG 70 is prohibited. Further, during the above power storage, the temperature T of the power storage device 112_BPower or electrical energy acceptance limit W that is a function of_INAnd export limit W_OUTThe range between and the actual power estimate P_B[= Generated power P_MG+ Power consumption P_RMGIf (negative)] is exceeded, the acceptance or take-out is prohibited.
[0034]
The brake control device 108 executes, for example, TRC control, ABS control, VSC control, etc., in order to increase the stability of the vehicle during start running, braking, and turning on a low μ road, or to increase the traction force. Wheel brakes 66WB, 68WB, 80WB, 82WB provided on the wheels 66, 68, 80, 82 are controlled via a brake control circuit. For example, in the TRC control, the wheel vehicle speed (the vehicle body speed converted based on the wheel rotation speed), for example, the right front wheel wheel vehicle speed V is based on a signal from a wheel rotation (wheel speed) sensor provided on each wheel._FR, Left front wheel speed V_FL, Right rear wheel speed V_RR, Left rear wheel speed 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 (V_FR, V_FL, V_RR, V_RLThe slowest speed), for example, the front wheel speed V which is the main driving wheel, for example._FAnd rear wheel speed V which is a non-drive wheel_RWhen the slip speed ΔV, which is the difference between the two, exceeds a preset control start judgment reference value ΔV1, slip judgment is made on the front wheels and the slip ratio R_S[= (ΔV / V_F) × 100%] is a preset target slip ratio R_S1The driving force of the front wheels 66 and 68 is reduced using the throttle actuator 21 and the wheel brakes 66WB and 68WB so as to enter the inside. In the ABS control, the front brakes 66 and 68 and the rear wheels 80 and 82 are used by using the wheel brakes 66WB, 68WB, 80WB, and 82WB so that the slip ratio of each wheel is within a predetermined target slip range during the braking operation. Maintain braking force and improve vehicle directional stability. Further, in the VSC control, when the vehicle is turning, the vehicle oversteer is based on a steering angle from a steering angle sensor (not shown), a yaw rate from a yaw rate sensor, longitudinal acceleration and lateral (lateral) acceleration from a biaxial G sensor, and the like. A tendency or an understeer tendency is determined, and one of the wheel brakes 66WB, 68WB, 80WB, and 82WB and the throttle actuator 21 are controlled so as to suppress the oversteer or understeer.
[0035]
FIG. 7 is a functional block diagram for explaining a drive control function for the RMG 70 functioning as an electric motor for driving the main part of the control function of the hybrid control device 104, that is, the rear wheels 80 and 82, for example. In FIG. 7, the required torque determining means 130 is a required torque T requested by the driver from the vehicle based on the actual vehicle speed V and the throttle opening θ based on, for example, a previously stored relationship (map) shown in FIG._faTo decide. The torque distribution ratio determining means 128 determines the load distribution ratio between the front wheels 66 and 68 and the rear wheels 80 and 82 that bear the load of the vehicle body based on the longitudinal acceleration G from the biaxial G sensor, for example. Front wheel torque distribution ratio K when driving four wheels based on load distribution ratio_tfAnd rear wheel torque distribution ratio K_tr(K_trIs a value smaller than 1 and the front wheel torque distribution ratio K_tf= 1-K_trIs). For example, this rear wheel torque distribution ratio K_trIs the static rear wheel load distribution ratio K_trwRoad surface inclination angle θ calculated from longitudinal acceleration G_LCorrection value determined based on (sin θ_L・ Value calculated by adding K) (= K_trw+ Sin θ_L・ K).
[0036]
The front side torque calculation means 132 is a required torque T determined by the required torque determination means 130._faAnd the front wheel torque distribution ratio K determined by the torque distribution ratio determination means 128._tfOr rear wheel torque T_rBased on the above, the front wheel torque T which is the torque command value required for the front wheels 66 and 68_f(= T_fa× K_tfOr T_fa-T_r) Is calculated. The front (front wheel) driving force control means 134 has a front wheel torque T calculated by the front side torque calculation means 132._fThe engine 14 and the MG 16 are controlled so that.
[0037]
The motor torque control means 136 also functions as a rear (rear wheel) torque control means, and controls the RMG 70 that drives the rear wheels 80 and 82 to change the torque of the rear motor torque calculation means 138. And rear motor driving means 140. The rear motor torque calculating means 138 is a required torque T determined by the required torque determining means 130._faAnd the rear wheel torque distribution ratio K determined by the torque distribution ratio determination means 128._trOr front wheel torque T_fAnd rear wheel torque T, which is a torque command value required for the rear wheels 80 and 82._r(= T_fa× K_trOr T_fa-T_f) That is, the first output torque is calculated. The rear motor driving means 140 has a rear wheel torque T calculated by the rear motor torque calculating means 138._rThe RMG 70 is supplied with power so that the RMG 70 is generated. 9 shows that the vehicle has a gradient angle of θ_LThe required torque T when traveling backward on an uphill road_fa, Front wheel torque T_f, Rear wheel torque T_rIs shown. Further, the solid line in FIG. 10 indicates the rear wheel torque T corresponding to the maximum rated torque of the RMG 70._rThe first output torque is determined within the maximum rated torque. RMG70 output torque is T_RMGThe gear ratio of the differential gear device 74 provided on the rear wheel side is γ_rThen, rear wheel torque T_rT_RMG× γ_rRMG 70 output torque T_RMGThere is a one-to-one relationship.
[0038]
The slope judging means 142 determines whether or not the slope of the running road of the vehicle is a slope with a predetermined value or more. For example, the standard vehicle acceleration and the actual vehicle acceleration when running on a flat road determined based on the throttle opening θ. Judgment based on the comparison. The slip determination means 144 determines whether or not a slip of a wheel, for example, the front wheels 66 and 68 has occurred, based on, for example, the rotational speed difference between the front wheel rotational speed and the rear wheel rotational speed.
[0039]
  The motor torque limiting means 146 is configured to limit the torque until the slip determination means 144 determines that the front wheels 66 and 68 have slipped when the slope determination means 142 determines that the vehicle is traveling on a slope. Value or upper limit torque T_UGAnd the rear wheel torque T calculated by the rear motor torque calculating means 138_rThe upper limit torque T_UGLimit to not exceed. That is, the rear wheel torque T_r(T_fa× K_tr≦ T_UG). This upper limit torque T_UGIs a value of about 50 Nm, for example.
[0040]
FIG. 11 is a flowchart for explaining the main part of the control operation of the hybrid control device 104, that is, the front and rear wheel torque control operation. 11, at step S1 corresponding to the required torque determining means 130 (hereinafter, step is omitted) S1, for example, based on the actual vehicle speed V and the throttle opening θ from the previously stored relationship (map) shown in FIG. Required torque T required by the driver_faIs determined. Next, in S2 corresponding to the torque distribution ratio determining means 128, for example, the load distribution ratio between the front wheels 66 and 68 and the rear wheels 80 and 82 that bear the load of the vehicle body based on the longitudinal acceleration from the biaxial G sensor. Is determined, and the front wheel torque distribution ratio K during four-wheel drive is based on the load distribution ratio._tfAnd rear wheel torque distribution ratio K_trIs determined.
[0041]
Next, in S3 corresponding to the slip determination means 144, whether or not the front wheels 66 and 68 have slipped is determined based on, for example, the rotational speed difference between the front wheel rotational speed and the rear wheel rotational speed. If the determination in S3 is negative, the upper limit torque T is determined in S4 corresponding to the motor torque limiting means 146._UGIs set to 50 Nm, for example. However, if the determination in S3 is affirmative, the upper limit torque T is determined in S7._UGIs infinite infinity or the rear wheel torque T shown in FIG._rBy setting a value higher than the maximum rating of the rear wheel torque T_rUpper limit torque T against_UGThe restrictions are removed.
[0042]
Upper limit torque T as described above_UGIs set, in S5 corresponding to the rear motor torque calculating means 138, the required torque T determined in S1 is set._faAnd the rear wheel torque distribution ratio K determined in S2 above._trOr front wheel torque T_fAnd the rear wheel torque T required for the rear wheels 80 and 82_r(= T_fa× K_trOr T_fa-T_f) And the rear wheel torque T_rThe RMG 70 is controlled so that. Further, in S6 corresponding to the front side torque calculating means 132, the required torque T determined in S1 above._faAnd the front wheel torque distribution ratio K determined in S2 above._tfAlternatively, the rear wheel torque T determined in S5_rThe front wheel torque T required for the front wheels 66 and 68 based on_f(= T_fa× K_tfOr T_fa-T_r) And the front wheel torque T_fThe engine 14 and the MG 16 are controlled so that.
[0043]
As described above, according to the present embodiment, the rear wheels 80 and 82 are driven by the motor torque limiter 146 (S4) until the slip determination unit 144 (S3) determines that the front wheels 66 and 68 have slipped. Is limited so that the torque output from the RMG (electric motor) 70 that drives the vehicle is lower than the first output torque determined during normal four-wheel drive, particularly in the four-wheel drive state when running on a slope. Longer mileage can be obtained.
[0044]
Further, according to the present embodiment, when the motor torque limiting means 146 (S4) determines that the traveling road of the vehicle is a slope, the RMG (electric motor) 70 that drives the rear wheels 80 and 82 is used. Since the torque output from the vehicle is limited to be lower than the first output torque, the traveling distance in the four-wheel drive state when traveling on a slope can be further increased, and the traveling path of the vehicle is not a slope. Sometimes, for example, a normal four-wheel drive state using the first output torque is obtained in accordance with a four-wheel drive request corresponding to a decrease in the road surface friction coefficient.
[0045]
In addition, according to the present embodiment, the engine 14 that operates by combustion of fuel and the MG 16 that operates as a generator and an electric motor are provided, and the operation mode is determined in accordance with the vehicle state from a plurality of operation modes. Since the front wheels 66 and 68 are rotationally driven by the main drive device (hybrid drive device) 10 that operates the engine 14 and the MG 16, the power storage device 112 or the Since electric power is supplied to the RMG (electric motor) 70, the traveling distance in the four-wheel drive state when traveling on a slope can be further increased.
[0046]
Further, according to the present embodiment, the MG 16 of the main drive device (hybrid drive device) 10 has a lower power generation capacity when the vehicle is traveling backward than when traveling forward, and the motor torque limiting means 146 is Torque output from the RMG (motor) 70 that drives the rear wheels 80 and 82 until the occurrence of slippage of the front wheels 66 and 68 is determined by the slip determination means 144 (S3) when the vehicle is traveling backward. Since the torque of the front wheels 66 and 68 is preferentially used by limiting the engine torque to be lower than the first output torque, the MG 16 has a lower power generation capacity than the forward travel, and the RMG (electric motor ) In reverse running with a power generation capacity that is less than the power consumption in normal four-wheel drive that outputs the first output torque from 70, especially in four-wheel drive when running on slopes Travel distance in the state can be obtained even longer.
[0047]
As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.
[0048]
For example, in the vehicle of the above-described embodiment, the front wheels 66 and 68 are driven by the main drive device 10 including the engine 14 and the MG 16, and the rear wheels 80 and 82 are driven by the auxiliary drive device 12 including the RMG 70. However, it may be a vehicle in which the main drive device 10 drives the rear wheels 80 and 82 and the auxiliary drive device 12 drives the front wheels 66 and 68. The auxiliary drive device 12 may be constituted by an electric motor. Further, the wheels provided in the vehicle do not necessarily have to be four wheels. For example, the left wheels and the right wheels of the rear wheels 80 and 82 may each be composed of a plurality of wheels.
[0049]
In the above-described embodiment, when the output torque of the RMG (electric motor) 70 is limited by the motor torque limiting means 146, the front side torque calculating means 132 may increase the amount by the limited torque. Good. In this way, the required torque T in the vehicle_faIs accurately obtained, and the acceleration performance of starting is maintained.
[0050]
The torque distribution ratio determining means 128 of the above-described embodiment determines the load distribution ratio between the front wheels 66 and 68 and the rear wheels 80 and 82 that bear the load of the vehicle body based on the longitudinal acceleration from the G sensor. Based on the load distribution ratio, the front wheel torque distribution ratio K during four-wheel drive_tfAnd rear wheel torque distribution ratio K_tr(K_trIs a value smaller than 1 and the front wheel torque distribution ratio K_tf= 1-K_trThe rear wheel torque distribution ratio K even on flat roads._trMay be a certain value, and may be continuously changed according to the vehicle weight distribution ratio.
[0051]
Further, the vehicle of the above-described embodiment is provided with the continuously variable transmission 20 in its power transmission path, but is provided with a planetary gear type or a constant meshing parallel two-axis stepped transmission. There may be.
[0052]
As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention implements in the aspect which added various change and improvement based on the knowledge of those skilled in the art. Can do.
[Brief description of the drawings]
FIG. 1 is a skeleton diagram illustrating a configuration of a power transmission device of a four-wheel drive vehicle including a drive control device according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a main part of a hydraulic control circuit that controls the planetary gear device of FIG. 1;
FIG. 3 is a diagram for explaining a control device provided in the four-wheel drive vehicle of FIG. 1;
4 is a graph showing a best fuel consumption rate curve that is a target of an engine operating point controlled by the engine control device of FIG. 3; FIG.
FIG. 5 is a chart showing control modes selected by the hybrid control device of FIG. 3;
6 is an alignment chart for explaining the operation of the planetary gear device in the ETC mode controlled by the hybrid control device of FIG. 3; FIG.
7 is a functional block diagram illustrating a main part of a control function of the hybrid control device of FIG.
8 is a diagram showing a pre-stored relationship used for determining a required torque in the required torque determining means of FIG. 7. FIG.
9 is a diagram for explaining torques calculated by front side torque calculation means and rear motor torque calculation means of FIG. 7; FIG.
10 is a diagram illustrating a torque limit value by the motor torque limiter in FIG. 7; FIG.
FIG. 11 is a flowchart for explaining a main part of the control operation of the hybrid control device of FIG. 3 and the like, and shows a front and rear wheel torque control routine.
[Explanation of symbols]
10: Main drive device (hybrid drive device)
14: Engine
16: Motor generator (MG)
66, 68: Front wheel (one wheel)
70: Rear motor generator (RMG, electric motor)
80, 82: Rear wheel (the other wheel)
138: Rear motor torque calculation means (motor torque calculation means)
144: Slip determination means
146: Motor torque limiting means

Claims (4)

A drive control device for a front and rear wheel drive vehicle in which one wheel of a front wheel and a rear wheel can be driven by an engine, and the other wheel can be driven by an electric motor,
Motor torque calculating means for calculating a first output torque to be output from an electric motor for driving the other wheel based on a driver's requested torque and a torque distribution ratio of the front and rear wheels for front and rear wheel driving;
Slip determination means for determining occurrence of slip of the one wheel;
Until the occurrence of slippage of the one wheel is determined by the slip determination means, the torque output from the electric motor that drives the other wheel is limited so as not to exceed a predetermined torque limit value. And a motor torque limiting means for canceling the torque limit value after the occurrence of slippage of the wheel is determined.   The motor torque limiting means limits the torque output from the electric motor that drives the other wheel when the vehicle traveling path is a slope so as not to exceed the predetermined torque limit value. The drive control device for a front and rear wheel drive vehicle according to Item 1.   A hybrid drive device including an engine that operates by combustion of fuel, a motor generator that operates as a generator and an electric motor, and operates the engine and the motor generator in an operation mode determined according to a vehicle state from a plurality of operation modes The drive control device for a front-rear wheel drive vehicle according to claim 1 or 2, wherein the one wheel is driven by the above. The motor generator of the hybrid drive device has a low power generation capacity when the vehicle is traveling backward as compared with when traveling forward.
The motor torque limiting means, according to claim 3 the torque output from the electric motor for driving the other wheel when a reverse running of the vehicle, is intended to limit so as not to exceed the predetermined torque limit value Drive control device for front and rear wheel drive vehicles.

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