JP4079077B2 - Vehicle travel control device - Google Patents

Description

  The present invention relates to a travel control device for a hybrid vehicle including an engine and a motor.

  Some vehicles control the vehicle speed by adjusting the throttle opening on the vehicle side (control device) even when the driver does not perform the accelerator operation. Vehicles that control vehicle speed on the vehicle side include cruise control that maintains the vehicle speed set by the driver even when the driver turns off the accelerator pedal, and vehicle speed that is controlled based on the inter-vehicle distance from the vehicle ahead. Yes (see Patent Documents 1 and 2).

Moreover, there exists a hybrid vehicle provided with an engine and a motor in a vehicle (refer patent documents 3-5). For hybrid vehicles, parallel hybrid vehicles that drive wheels with an engine and motor, series hybrid vehicles that drive wheels with either the engine or motor, one of the front wheels or rear wheels is driven with the engine, and the other is driven with the motor There are various forms such as a four-wheel drive hybrid vehicle.
Japanese Patent Application Laid-Open No. 11-301311 JP 2002-192980 A JP 2002-213273 A JP 2001-82218 A Japanese Patent Laid-Open No. 2002-276406

  However, there is no hybrid vehicle that controls the vehicle speed on the vehicle side (control device) even when the driver does not perform the accelerator operation. In particular, since the hybrid vehicle aims to improve fuel consumption, it is desired to reduce fuel consumption even when the vehicle speed is controlled on the vehicle side.

  Therefore, an object of the present invention is to provide a vehicle travel control device that realizes vehicle speed control with low fuel consumption in a hybrid vehicle.

A vehicular travel control apparatus according to the present invention is a vehicular travel control apparatus that controls a travel state in a hybrid vehicle including an engine and a motor, the accelerator pedal detecting means detecting that the accelerator pedal is turned off, and the accelerator pedal. When the detection means detects that the accelerator pedal is turned off , the vehicle speed control means for controlling the vehicle speed so that the vehicle speed of the hybrid vehicle is maintained or the deceleration is reduced, and when the vehicle speed is controlled by the vehicle speed control means , to the engine The fuel cut control means for stopping the fuel supply, the acceleration request detection means for detecting the driver's acceleration request, and the acceleration request detection means when the fuel supply to the engine is stopped by the fuel cut control means When's acceleration request is detected and to resume restarting means the fuel supply to the engine For example, to increase the torque assist amount when restarting the engine by the motor when restarting the fuel supply to the engine by restarting means, have rows by the torque assist of the motor vehicle speed control by the speed control means, the vehicle speed control means When controlling the vehicle speed, charge the battery by subtracting the estimated power required to assist the engine when the engine is restarted when restarting the fuel supply to the engine by the restart means when the motor speed is controlled by the motor It is set based on quantity .

  In this vehicle travel control device, vehicle speed control is performed when the driver turns off the accelerator pedal. Normally, when the accelerator is off, the driving force cannot be obtained and the vehicle decelerates. However, this control device maintains the vehicle speed at a constant speed or reduces the vehicle speed according to the accelerator off state (accelerator acceleration, road surface μ, distance between vehicles by laser radar, etc.). Car speed control such as variable speed is performed, and the vehicle speed is adjusted on the vehicle side. Therefore, in the control device, when acceleration is necessary to maintain the vehicle speed at a constant speed or slow down the deceleration, the motor is driven, and torque is assisted by the driving force to perform a predetermined acceleration. obtain. In this way, when the accelerator is off, the control device adjusts the vehicle speed not by the engine but by the driving force by the motor or the driving at the engine high efficiency operating point and the assist running by the motor, so that the energy efficiency for generating the driving force is increased. The fuel consumption can be improved. In particular, since the vehicle speed does not decrease even when the accelerator is off as compared with the case where torque assist is not performed, the number of accelerator operations by the driver, the amount of accelerator operation, and the accelerator operation speed are reduced, thereby improving fuel efficiency.

  The hybrid vehicle is a vehicle including an engine and a motor, and is a vehicle that can obtain a driving force by at least the motor. For example, one of the parallel hybrid vehicle, the series hybrid vehicle, the front wheel, and the rear wheel is driven by the engine. There is a four-wheel drive hybrid vehicle in which the other is driven by a motor. The vehicle speed control includes, for example, a control for holding the vehicle speed when the accelerator pedal is turned off, a control for changing the deceleration of the vehicle speed, and a control for holding the vehicle speed set by the driver.

The vehicle travel control apparatus of the present invention includes target value setting means for setting a target value of the vehicle speed when the vehicle speed is controlled by the vehicle speed control means, and the target value setting means determines the vehicle speed according to the amount of charge of the battery. The target value may be changed .

  In this vehicle travel control device, the target vehicle speed is changed by the target vehicle speed changing means according to the amount of charge of the battery, and the driving force (and hence acceleration) by the motor necessary to reach the target vehicle speed is generated. Thus, in the control device, the torque assist amount (target vehicle speed) by the motor is changed according to the charge amount of the battery (specifically, the torque assist amount is decreased according to the decrease in the charge amount). Power consumption can be suppressed, and the assist time by the motor can be lengthened. As a result, energy efficiency in vehicle speed control is improved, and fuel efficiency is improved.

The vehicle travel control apparatus of the present invention may include a fuel cut control means for stopping the supply of fuel to the engine when the vehicle speed is controlled by the vehicle speed control means .

  In this vehicle travel control device, the fuel cut control means stops the fuel supply to the engine during vehicle speed control, and does not supply unnecessary fuel to the engine. As a result, the fuel consumption can be further improved.

  Note that the vehicle travel control device of the present invention may include means for configuring neutral range control (control for automatically setting the shift position to the neutral range). Since this neutral range control can reduce the friction loss of the engine, the motor assist can be controlled more efficiently.

In the vehicle travel control apparatus of the present invention, the hybrid vehicle is a vehicle including a fluid coupling interposed between the engine and the wheels, and a coupling means for mechanically coupling the input and output of the fluid coupling. There may be provided a connection interruption means for interrupting mechanical connection by the connection means when fuel supply to the engine is stopped by the fuel cut control means .

A vehicular travel control apparatus according to the present invention is a vehicular travel control apparatus that controls a travel state in a hybrid vehicle including an engine and a motor, the accelerator pedal detecting means detecting that the accelerator pedal is turned off, and the accelerator pedal. Vehicle speed control means for controlling the vehicle speed so that the vehicle speed of the hybrid vehicle is maintained or the deceleration is reduced when it is detected by the detection means that the accelerator pedal is turned off, and the vehicle speed control by the vehicle speed control means is controlled by the motor torque. The vehicle speed control means performs the assist, and the vehicle speed control means selects one of the vehicle speed holding control and the deceleration control based on a predetermined deceleration based on the charge amount of the battery.

In the vehicle travel control apparatus of the present invention, it is preferable that the predetermined deceleration is set so that a decrease in the vehicle speed is suppressed as compared with a case where the vehicle speed control by the vehicle speed control means is not performed.

The vehicle travel control apparatus of the present invention may be configured to assist the restart of the engine by the motor when the driver's acceleration request is detected while the vehicle speed is controlled by the vehicle speed control means .

  In this vehicular travel control device, when a driver's acceleration request is detected during vehicle speed control, the driving force of the engine is assisted by the driving force of the engine until the driving force of the engine corresponding to the acceleration request is sufficiently transmitted to the axle. With this assist, the engine can be restarted smoothly and promptly, and acceleration according to the driver's acceleration request can be generated.

In the vehicle travel control apparatus according to the present invention, the acceleration request detecting means for detecting the driver's acceleration request, and when the fuel supply to the engine is stopped by the fuel cut control means, the acceleration request detecting means A restart means for restarting fuel supply to the engine when an acceleration request is detected may be provided, and the torque assist amount by the motor may be increased when the restart means restarts fuel supply to the engine. Furthermore, in the vehicle travel control apparatus of the present invention, it is preferable that the torque assist amount of the motor is set based on the charge amount of the battery when the restarting means restarts the fuel supply to the engine.

  In this vehicle travel control device, the assist amount of the motor when the engine is restarted is set according to the charge amount of the battery (specifically, the assist amount is also reduced when the battery charge amount is small). By setting the assist amount in this way, the charge amount of the battery is not drastically reduced, the reduction of the torque assist amount by the motor at the time of vehicle speed control can be prevented, and the deterioration of drivability can be prevented. it can.

In the vehicular travel control apparatus of the present invention, when the vehicle speed is controlled by the vehicle speed control means, the estimated torque required for assisting the motor when the restarting means resumes the fuel supply to the engine by using the torque assist amount of the motor. It is preferable to set based on the subtracted battery charge.

  In this vehicular travel control device, the power consumption of the motor when assisting the engine restart is estimated, and the torque assist amount of the motor is set based on the charge amount of the battery obtained by subtracting the estimated power consumption. . Therefore, when the engine is restarted in response to the driver's acceleration request, the battery has sufficient power to assist with the motor, so that the motor can always assist.

  According to the present invention, in a hybrid vehicle, when there is no driver's accelerator operation, vehicle speed control can be performed with low fuel consumption by utilizing the driving force of a motor.

  Embodiments of a vehicle travel control apparatus according to the present invention will be described below with reference to the drawings.

  In the present embodiment, the vehicular travel control apparatus according to the present invention is applied to an ECU [Electronic Control Unit] of a parallel hybrid vehicle capable of four-wheel drive in which rear wheels are driven by an engine and front wheels are driven by a motor / generator. To do. The ECU according to the present embodiment controls an engine, a motor, an automatic transmission, and the like, and particularly performs vehicle speed control when the accelerator is off.

  The configuration of the hybrid vehicle 1 will be described with reference to FIG. FIG. 1 is a configuration diagram of a hybrid vehicle equipped with an ECU according to the present embodiment.

  The hybrid vehicle 1 includes an engine 2 that drives the rear wheels RW and RW and two motor generators 3 and 3 that drive the front wheels FW and FW, respectively. The hybrid vehicle 1 normally travels as a rear wheel drive vehicle that drives the rear wheels RW and RW by the driving force of the engine 2, and also drives the front wheels FW and FW by the driving force of the motor generators 3 and 3 as necessary. Travels as a wheel drive vehicle. In particular, when the accelerator is off, the hybrid vehicle 1 travels as a front wheel drive vehicle that drives only the rear wheels RW and RW by the driving force of the motor generators 3 and 3.

  In the hybrid vehicle 1, the driving force of the engine 2 is converted by the automatic transmission 4 and transmitted to the rear differential 6 via the propeller shaft 5. In the hybrid vehicle 1, the driving force is transmitted from the rear differential 6 to the drive shaft 7 evenly to the left and right, and the driving force is transmitted from the drive shaft 7 to the rear wheels RW and RW. The automatic transmission 4 includes a lock-up clutch 4a, and the engine 2 can be mechanically connected directly by the lock-up clutch 4a. Further, in the hybrid vehicle 1, the driving force of the engine 2 is transmitted to the generator 9 via the pulley 8. The generator 9 generates power using the driving force of the engine 2. In the hybrid vehicle 1, the driving force of the motor / generators 3, 3 is transmitted to the front wheels FW, FW via the left and right drive shafts 10, 10, respectively. In the hybrid vehicle 1, the power train including the engine 2, the motor / generator 3, the automatic transmission 4, and the like is comprehensively controlled by the ECU 11.

  The engine 2 includes an electronically controlled fuel injection device 2a, and fuel is injected from the electronically controlled fuel injection device 2a in response to a command from the ECU 11. The electronically controlled fuel injection device 2a has a fuel cut function, and stops the supply of fuel to the engine 2 in response to a command from the ECU 11.

  Motor generators 3 and 3 are AC synchronous motors, and are driven by three-phase AC power from inverters 12 and 12, respectively. Further, the motor generators 3 and 3 have a function as a generator, and convert the rotational energy of the front wheels FW and FW into electric energy to perform regenerative power generation. The inverters 12 and 12 convert the electric power charged in the high voltage battery 13 from direct current to alternating current, and supply it to the motor generators 3 and 3. The inverters 12 and 12 convert the electric power generated by the regenerative power generation from the motor generators 3 and 3 from AC to DC and charge the high voltage battery 13. Furthermore, the high voltage battery 13 is also charged with the power generated by the generator 9. The electric power of the generator 9 may be used as it is by auxiliary equipment. It is also possible to charge the 12V battery 15 with the electric power charged in the high voltage battery 13 via the DC-DC converter 14. The motor may be a DC motor or a synchronous motor.

  The ECU 11 will be described in detail with reference to FIGS. FIG. 2 is a first map showing the provisional assist amount according to the vehicle speed and SOC held by the ECU. FIG. 3 is a diagram showing a state when the accelerator pedal is turned on from off in the hybrid vehicle, (a) is a diagram showing the power of the motor, and (b) is a diagram showing an on / off state of the accelerator pedal. (C) is a diagram showing an on / off state of the lockup clutch. FIG. 4 is a second map showing the estimated SOC corresponding to the estimated motor energy consumption held by the ECU. FIG. 5 is a third map showing the estimated slip ratio according to the provisional assist amount and the road surface friction coefficient held by the ECU. FIG. 6 is a fourth map showing the final assist amount according to the estimated slip ratio held by the ECU. FIG. 7 is a diagram showing vehicle speed holding control in the ECU, (a) is a diagram showing an on / off state of an accelerator pedal, and (b) is a diagram showing a vehicle speed. FIG. 8 is a diagram showing variable deceleration control in the ECU, (a) is a diagram showing the on / off state of the accelerator pedal, and (b) is a diagram showing the vehicle speed. FIG. 9 is a diagram illustrating a state when the hybrid vehicle is switched from the motor assist mode to the regenerative mode, in which (a) illustrates an accelerator pedal on / off state, and (b) illustrates a brake pedal on state. FIG. 4 is a diagram showing an off state, (c) is a diagram showing a change in hydraulic pressure of the master cylinder, and (d) is a diagram showing a vehicle speed.

  The ECU 11 is an electronic control unit including a CPU [Central Processing Unit], a ROM [Read Only Memory], a RAM [Random Access Memory], and the like. The ECU 11 is connected to various sensors, sets various control amounts based on detection values from the various sensors, the engine 2 (electronically controlled fuel injection device 2a, throttle valve (not shown), etc.), motor / generator 3 and the like. , 3 (actually inverters 12, 12) and automatic transmission 4 (lock-up clutch 4a, etc.) are controlled. The ECU 11 normally controls the engine 2 based on the accelerator opening and the like so as to function as a rear wheel drive vehicle. Further, the ECU 11 determines whether or not four-wheel drive is necessary based on the road surface condition (for example, road surface friction coefficient, straddle road) or the like, and controls the inverters 12 and 12 when four-wheel drive is necessary. Motor generators 3 and 3 are driven to function as a four-wheel drive vehicle. Further, when the accelerator is off, the ECU 11 executes vehicle speed control (particularly referred to as steady travel assist control), controls the inverters 12 and 12 to drive the motor generators 3 and 3 to function as a front wheel drive vehicle.

  In this vehicle speed control, even when the driver does not operate the accelerator pedal 16 (the driver does not request acceleration), the vehicle speed (ECU 11) controls the vehicle speed. In particular, this vehicle speed control is intended to further improve fuel efficiency in the hybrid vehicle 1 and uses the driving force of the motor / generators 3 and 3 to assist the torque during the steady running (set to the front wheel drive state). In order to realize this steady travel assist control, the ECU 11 has a control determination function, a control initial function, a control switching function, a vehicle speed holding control function, a variable deceleration control function, a restart assist function, and a regeneration function. In order to acquire information necessary for performing these functions, the ECU 11 includes a laser radar sensor 20, an accelerator pedal stroke sensor 21, wheel speed sensors 22, 22, 22, 22, an SOC [State Of Charge] sensor 23, Current sensors 24 and 24 and a brake pedal stroke sensor 25 are connected, and a detection value is taken from each sensor.

  The laser radar sensor 20 is a sensor that irradiates a laser beam forward and measures the time until the laser beam is reflected and returned. In addition to the laser radar sensor 20, other sensors such as a millimeter wave radar sensor may be used. The accelerator pedal stroke sensor 21 is a sensor that detects an operation amount of the accelerator pedal 16. The wheel speed sensor 22 is a sensor that is provided on each of the four wheels and detects the rotational speed of each wheel. Although the vehicle speed is estimated based on the detection value of the wheel speed sensor 22, other vehicle speed sensors other than the wheel speed sensor 22 may be used. The SOC sensor 23 is a sensor that detects the charge amount of the high voltage battery 13. The current sensor 24 is a sensor that detects each phase current of the three-phase AC supplied from the inverter 12. The brake pedal stroke sensor 25 is a sensor that detects an operation amount of the brake pedal 17.

  The control determination function is a function for determining whether or not safe traveling can be performed in relation to the vehicle ahead when controlling the vehicle speed on the vehicle side. In the control determination function, the inter-vehicle distance from the vehicle ahead is calculated based on the detection value from the laser radar sensor 20, and when the inter-vehicle distance is equal to or greater than the predetermined distance, it is determined that the steady travel assist control is possible and less than the predetermined distance. In this case, it is determined that the steady travel assist control is not possible. Alternatively, in the control determination function, the relative speed with the vehicle ahead is calculated based on the detection value from the laser radar sensor 20, and when the relative speed is less than the predetermined speed, it is determined that the steady travel assist control is possible, When the speed is higher than the speed, it is determined that the steady travel assist control is impossible. In the control determination function, determination may be performed using both the inter-vehicle distance and the relative speed. The predetermined distance and the predetermined speed are reference values for determining whether or not safe driving can be performed, and are set in advance by experiments or simulations. When the control determination function determines that there is no problem in safe driving in performing steady driving assist control, whether or not the accelerator pedal 16 is off (fully closed) based on the detection value from the accelerator pedal stroke sensor 21. When the switch is off, the control shifts to the initial control function, and when the switch is on, the control shifts to another control according to the accelerator operation (particularly, when the switch is switched from off to on).

  Further, in the control determination function, it may be determined whether or not the steady travel assist control is performed based on the surrounding situation of the vehicle. The surrounding conditions of the vehicle are road surface friction coefficient, weather, traffic jam information, and the like. For example, when the road surface friction coefficient is low, in the case of rain or strong wind in the weather, or in the case of traffic congestion, it is determined that the steady travel assist control is not possible. As a method for detecting the road surface friction coefficient, a method used in ABS (Anti-Lock Brake System) control or the like is used, and it is obtained by calculation based on the wheel speed detected by the sensor, the longitudinal acceleration of the vehicle, or the like. VICS [Vehicle Information Communication Systems] is used as a method for obtaining weather and traffic information.

  If the laser radar sensor 20 and a means for acquiring the surrounding situation are not provided, it is determined whether or not steady travel assist control is possible based on the driver's brake operation (brake operation amount or brake operation speed) or the like. It may be determined whether or not to reduce the assist amount when performing the travel assist control.

  The initial control function is a function that performs initial processing in steady travel assist control. In the initial control function, a command signal for turning off the lock-up clutch 4a is transmitted to the automatic transmission 4, and the lock-up clutch 4a is turned off. This is because if the lock-up clutch 4a is turned on, the friction of the engine 2 is transmitted to the drive shaft 7, so that rotational energy is lost due to the friction. Therefore, in order to reduce the friction, the lockup clutch 4a is turned off. By reducing this friction, the assist amount of the motor generators 3 and 3 in front wheel traveling can be reduced. As a method for reducing friction, neutral range control (control for automatically setting the shift to the neutral range) may be used. In the initial control function, a command signal for fuel cut is transmitted to the electronically controlled fuel injection device 2a to stop the supply of fuel to the engine 2. In the initial control function, the vehicle speed is calculated based on the detection values from the wheel speed sensors 22, 22, 22, and 22, and the vehicle speed is stored as the current vehicle speed (A). In the initial control function, the assist amount (final assist amount) by the motor generators 3 and 3 is based on the current vehicle speed (A) and the actual SOC (charge amount) of the high-voltage battery 13 from the SOC sensor 23. Ask for.

  With reference to FIGS. 2 to 6, how to determine the assist amount will be described in detail. In the ECU 11, four maps M1 to M4 are held in the ROM in order to obtain the assist amount. These maps M1 to M4 are set in advance by experiments, simulations, or the like. The first map M1 is a three-dimensional map in which the provisional assist amount is associated with the vehicle speed and the SOC (see FIG. 2). The second map M2 is a two-dimensional map in which the estimated SOC is associated with the estimated motor energy consumption (see FIG. 4). The third map M3 is a three-dimensional map in which the estimated slip ratio is associated with the provisional assist amount and the road surface friction coefficient (see FIG. 5). The fourth map M4 is a two-dimensional map in which the final assist amount is associated with the estimated slip ratio (see FIG. 6).

  First, using the first map M1, the provisional assist amount is obtained from the vehicle speed (the current vehicle speed (A) is used in the initial control function) and the SOC (see FIG. 2). The SOC used here is an SOC obtained by subtracting the estimated SOC from the actual SOC detected by the SOC sensor 23. The estimated SOC is an estimated value of electric power consumed by assisting the motor generators 3 and 3 when the engine 2 is restarted when the accelerator pedal 16 is turned on.

  The reason why the estimated SOC is subtracted will be described below. During the steady travel assist control, the lockup clutch 4a is turned off. As shown in FIG. 3C, the lock-up clutch 4a has a delay time T until it changes from the off state (released state) to the on state (engaged state). Therefore, when the accelerator pedal 16 is switched from OFF to ON (see FIG. 3B), the engine 2 and the drive shaft 7 are directly connected during the delay time T even if a command signal for turning on the lockup clutch 4a is transmitted. It will not be in a state. Accordingly, since the driving force of the engine 2 is not sufficiently transmitted to the rear wheels RW and RW, acceleration corresponding to the accelerator operation cannot be obtained and acceleration is slow. Therefore, the ECU 11 assists the restart of the engine 2 by the driving force of the motor generators 3 and 3 when the accelerator pedal 16 is switched from OFF to ON. Electric power (that is, estimated SOC) necessary for assisting the restart is secured in advance, and smooth acceleration according to the accelerator operation can be performed when the engine 2 is restarted.

  FIG. 3 (a) shows the power MP (W) of the motor / generators 3 and 3 required for obtaining smooth acceleration with no delay in the restart of the engine 2. The motor power MP is determined by road surface resistance (road surface friction coefficient), and increases as the road surface friction coefficient increases. As the motor power MP, a value corresponding to a road surface friction coefficient is set in advance by experiment, simulation, or the like, and is held in the ROM of the ECU 11. The delay time T is also measured in advance and held in the ROM of the ECU 11. Therefore, the ECU 11 obtains the motor power MP based on the road surface friction coefficient, and multiplies the obtained motor power MP by the delay time T to obtain an estimated motor consumption energy value. Then, using the second map M2, an estimated SOC is obtained from this estimated motor energy consumption value (see FIG. 4). Incidentally, as described above, the road surface friction coefficient is obtained based on the vehicle speed, the vehicle longitudinal acceleration, and the like.

  When the provisional assist amount is obtained from the vehicle speed and the SOC, the estimated slip ratio is obtained from the provisional assist amount and the road surface friction coefficient using the third map M3 (see FIG. 5). Then, the final assist amount is obtained from the estimated slip ratio using the fourth map M4 (see FIG. 6). As described above, the ECU 11 determines the assist amount (final assist amount) in consideration of the road surface condition, so that the front wheels FW and FW do not slip by the driving force of the motor generators 3 and 3. As a result, since no extra energy is given to the front wheels FW, FW, energy efficiency is improved.

  Note that the assist amount may be simply obtained from the vehicle speed and the SOC without considering the road surface condition. In addition, in a vehicle that does not have a lock-up clutch and does not have acceleration when restarting the engine, it is not necessary to obtain the estimated SOC and obtain the assist amount based on the SOC obtained by subtracting the estimated SOC.

  The control switching function is a function for switching between vehicle speed holding control and variable deceleration control. In the control switching function, it is determined whether or not the high voltage battery 13 is in a fully charged state based on a detection value from the SOC sensor 23. If the high voltage battery 13 is in a fully charged state, the control proceeds to the vehicle speed holding control function. Shifts to the variable deceleration control function. The switching control may be performed in consideration of the SOC of the 12V battery 15 and the state of charge.

  The vehicle speed holding control function is a function of controlling the motor generators 3 and 3 in order to hold the vehicle speed at the current vehicle speed (A). When the vehicle speed holding control is performed, when the accelerator pedal 16 is turned off from on (see FIG. 7A), the vehicle speed is held at the vehicle speed when the accelerator is turned off by the assistance of the motor generators 3 and 3 (FIG. 7). (See the solid line in (b)). Incidentally, when the motor generators 3 and 3 do not assist, the vehicle speed decreases (see the broken line in FIG. 7B).

  In the vehicle speed holding control function, first, the current vehicle speed (A) is set as a cruise vehicle speed target. In the vehicle speed holding control function, the assist amount by the motor / generators 3 and 3 is obtained based on the cruise vehicle speed target and the SOC of the high voltage battery 13 in the same manner as described above. When the assist amount is obtained, the vehicle speed holding control function calculates electric power (current) necessary for obtaining the motor rotation speed corresponding to the assist amount, and sends command signals for supplying the electric power to the inverters 12 and 12, respectively. Send. Further, in the vehicle speed holding control function, the currents 24 and 24 are fed back to the respective phase currents actually supplied by the inverters 12 and 12, and the inverters 12 and 12 (and thus the motor generators 3 and 3) are controlled by PID control. Each is feedback controlled. The motor speed of the motor / generators 3 and 3 may be detected and feedback control may be performed based on the actual motor speed.

  In the vehicle speed holding control function, when it is determined that the SOC of the high-voltage battery 13 decreases and the estimated SOC cannot be secured, the lock-up clutch 4a is turned on from off and the assist amount by the motor generators 3 and 3 is increased. Decrease gradually and stop assisting by motor generators 3 and 3. Alternatively, when the vehicle speed holding control function determines that the estimated SOC cannot be secured, the vehicle speed holding control function shifts to the variable deceleration control function, and suppresses the decrease in the SOC.

  The variable deceleration control function is a function for controlling the motor generators 3 and 3 to decelerate at a vehicle speed corresponding to the SOC of the high voltage battery 13. When the SOC of the high voltage battery 13 is not fully charged, the deceleration of the vehicle speed is adjusted in order to suppress the decrease in the SOC. By suppressing the decrease in the SOC, the assist time by the motor generators 3 and 3 can be lengthened, and the energy efficiency can be improved. Specifically, the deceleration is reduced as the SOC increases (as a result, the vehicle speed does not decrease much from the current vehicle speed (A)), and the deceleration is increased as the SOC decreases (as a result, the vehicle speed becomes the current vehicle speed). Greatly reduced from (A)). When the deceleration vehicle speed holding control is performed, if the accelerator pedal 16 is turned off from on (see FIG. 8 (a)), the vehicle speed decreases with a predetermined deceleration (see the solid line in FIG. 8 (b)). 3 and 3, the acceleration is smaller than the deceleration (see the broken line in FIG. 8B) when the motor generators 3 and 3 do not assist.

  In the variable deceleration control function, first, a vehicle speed corresponding to the SOC of the high voltage battery 13 is set as a cruise vehicle speed target. Incidentally, as the cruise vehicle speed target, the higher the SOC, the higher the vehicle speed is set, and the lower the SOC, the lower the vehicle speed is set. In the variable deceleration control function, as in the vehicle speed maintaining function, the assist amount is obtained based on the cruise vehicle speed target and the SOC of the high voltage battery 13, and a command signal for supplying electric power corresponding to the assist amount is provided to the inverter 12. , 12 and further, feedback control of the inverters 12, 12 is performed by PID control. The cruise vehicle speed target may be set in consideration of the SOC of the 12V battery 15 and the state of charge.

  The restart assist function is a function for assisting the motor / generators 3 and 3 to restart the engine 2 when the accelerator pedal 16 is turned on from the OFF state during the steady travel assist control. In the restart assist function, when it is detected that the accelerator pedal 16 is switched from OFF to ON based on a detection value from the accelerator pedal stroke sensor 21, a command signal for turning on the lockup clutch 4a is transmitted to the automatic transmission 4. Then, the lockup clutch 4a is turned on. Further, in the restart assist function, a command signal for stopping the fuel cut is transmitted to the electronically controlled fuel injection device 2a, and the supply of fuel to the engine 2 is resumed. Further, in the restart assist function, the motor power MP (that is, the assist amount by the motor generators 3 and 3) is obtained based on the road surface friction coefficient. At this time, in the restart assist function, the assist amount of the motor / generator 3 is determined in consideration of the actual SOC of the high voltage battery 13 from the SOC sensor 23. Incidentally, in the ECU 11, electric power for assisting the restart of the engine 2 as the estimated SOC is secured in the high voltage battery 13 as the estimated SOC, but the SOC corresponding to the actually required assist amount is the high voltage battery 13. Therefore, an appropriate assist amount corresponding to the actual SOC is set. When the assist amount is determined, the restart assist function calculates electric power (current) necessary for obtaining the motor rotation speed corresponding to the assist amount, and sends a command signal for supplying the electric power to the inverters 12 and 12, respectively. Send. Furthermore, in the restart assist function, the current actually supplied from the inverters 12 and 12 is fed back from the current sensors 24 and 24, and the inverters 12 and 12 (and thus the motor generators 3 and 3) are fed back by PID control. Control. In the restart assist function, when the lock-up clutch 4a is turned on (when the delay time T elapses), the assist amount is gradually reduced and gradually returned to the rear wheel traveling by the engine 2.

  When the brake pedal 17 is turned on, the regenerative function is a function that stops the assist by the motor generators 3 and 3 and performs regenerative power generation. In the regenerative function, when it is detected that the brake pedal 17 is turned on based on the detection value from the brake pedal stroke sensor 25 (see FIG. 9B), the regeneration function is based on the detection value from the brake pedal stroke sensor 25. The brake operation speed is obtained, and the SOC of the high voltage battery 13 is taken in based on the detected value from the SOC sensor 23. In the regeneration function, the regeneration amount is obtained based on the brake operation speed and the SOC of the high voltage battery 13. As a method for obtaining the regenerative amount, for example, a map set by experiment or simulation is used. Incidentally, the regeneration amount is increased as the brake operation speed is increased, the brake depression amount is increased, or the SOC is decreased. As the brake operation speed increases and the brake depression amount increases, the degree of increase in the hydraulic pressure of the master cylinder increases (in FIG. 9C, the degree of increase increases in the order of a, b, and c). The deceleration is also increased (in FIG. 9D, the deceleration is increased in the order of a, b, and c). Further, in the regeneration function, a command signal for charging the high voltage battery 13 with electric power corresponding to the amount of regeneration is transmitted to each of the inverters 12 and 12.

  With reference to FIG. 1, main control in the steady travel assist control in the ECU 11 will be described along the flowchart of FIG. 10. FIG. 10 is a flowchart showing steady travel assist control in the ECU. Note that the ECU 11 repeatedly executes the following series of processes at regular intervals.

  First, the ECU 11 determines, based on the inter-vehicle distance from the vehicle in front, etc., whether or not there is an obstacle to safe driving in performing steady driving assist control (S1). If the ECU 11 determines that the safe travel can be performed even if the steady travel assist control is performed, the ECU 11 performs the steady travel assist control (S2). If the ECU 11 determines that the safe travel cannot be performed, the ECU 11 The travel assist control is stopped (S3).

  Next, the ECU 11 determines whether or not the accelerator pedal 16 is off (S4). When the accelerator pedal 16 is on, the ECU 11 shifts to control according to the accelerator operation. In particular, when the accelerator pedal 16 is switched from OFF to ON during steady travel assist control, the ECU 11 performs assist control by the motor generators 3 and 3 in order to assist acceleration when the engine 2 is restarted. With the assistance of the motor generators 3 and 3, in the hybrid vehicle 1, acceleration corresponding to the driver's accelerator operation is obtained and smooth acceleration is achieved.

  When the accelerator pedal 16 is off, the ECU 11 turns off the lock-up clutch 4a and stops the supply of fuel to the engine 2. In this manner, energy loss due to friction of the engine 2 is reduced and fuel consumption is also suppressed. Further, the ECU 11 stores the current vehicle speed (A) (S5). Further, the ECU 11 sets the final assist amount based on the SOC of the high voltage battery 13 and the current vehicle speed (A) (S6). At this time, the ECU 11 sets the optimum final assist amount in consideration of the road surface condition and electric power required when the engine 2 is restarted.

  Subsequently, the ECU 11 determines whether or not the SOC of the high voltage battery 13 is in a fully charged state (S7). Then, the ECU 11 performs vehicle speed holding control when the battery is fully charged (S8), and performs variable deceleration control when the battery is not fully charged (S9). In this way, the ECU 11 determines whether to maintain the vehicle speed controlled according to the SOC of the high voltage battery 13 or to decrease the vehicle speed at a predetermined deceleration rate. Therefore, the electric power (energy) stored in the high voltage battery 13 is determined. ) Can be consumed efficiently.

  When shifting to the vehicle speed holding control, the ECU 11 sets the current vehicle speed (A) as the cruise vehicle speed target (S10). Then, the ECU 11 sets the final assist amount based on the SOC of the high voltage battery 13 and the cruise vehicle speed target, and further considering the road surface condition and the electric power required when the engine 2 is restarted (S11). Further, the ECU 11 feedback-controls the motor generators 3, 3 (actually, the inverters 12, 12) by PID control so that the set assist amount is obtained (S12). Then, in the hybrid vehicle 1, the vehicle speed is maintained at the vehicle speed when the accelerator pedal 16 is turned off, even though the accelerator pedal 16 is turned off. At this time, the hybrid vehicle 1 does not consume fuel by the engine 2 in order to maintain this vehicle speed.

  When shifting to the variable deceleration control, the ECU 11 sets the cruise vehicle speed target according to the SOC of the high voltage battery 13 (S13). Then, the ECU 11 sets the final assist amount in the same manner as in the process of S11 (S14), and further feedback controls the motor generators 3 and 3 in the same manner as in the process of S12 (S15). Then, in the hybrid vehicle 1, the vehicle speed decreases at a deceleration smaller than the normal vehicle speed deceleration when there is no assistance by the motor generators 3 and 3. At this time, in the hybrid vehicle 1, fuel is not consumed by the engine 2 in order to suppress the decrease in the vehicle speed. Further, since the assist amount is set in consideration of the SOC (as a result, the deceleration of the vehicle speed is adjusted), it is possible to secure a long assist time and efficiently consume power.

  As described above, the number of accelerator operations by the driver, the amount of accelerator operation, the accelerator operation speed, and the like can be suppressed by keeping the vehicle speed constant or suppressing the decrease in the vehicle speed by making the vehicle speed deceleration slower than usual. . As a result, the amount of fuel supplied to the engine 2 can be reduced.

  According to the ECU 11, even when the accelerator pedal 16 is turned off, the vehicle speed control is performed using the driving force of the motor generators 3 and 3, so that a decrease in the vehicle speed can be suppressed and the fuel consumption can be improved. Further, since the ECU 11 determines the assist amount by the motor generators 3 and 3 in consideration of the SOC of the high voltage battery 13, the power can be consumed efficiently, the assist time can be increased, and the energy efficiency can be improved. Can do. Further, in the ECU 11, the vehicle speed control further improves fuel efficiency by cutting the fuel, and suppresses unnecessary energy consumption by turning off the lock-up clutch 4a.

  Further, since the ECU 11 secures electric power necessary for assisting when the engine 2 is restarted, the engine 2 can be restarted smoothly. Furthermore, since the ECU 11 performs vehicle speed control in consideration of the vehicle ahead, the surrounding conditions, and the like, safe traveling can be performed even during vehicle speed control.

  As mentioned above, although embodiment which concerns on this invention was described, this invention is implemented in various forms, without being limited to the said embodiment.

  For example, in the present embodiment, the present invention is applied to a parallel hybrid vehicle capable of four-wheel drive, but the present invention can also be applied to other forms of hybrid vehicles such as a two-wheel drive parallel hybrid vehicle and a series hybrid vehicle.

  Further, in the present embodiment, the present invention is applied to the case where the vehicle speed holding control or the variable deceleration control is performed on the vehicle side when the accelerator pedal is off, but other control such as a cruise control or a control for maintaining the distance between the vehicles ahead. It can also be applied to the control.

  In this embodiment, the engine, the motor, and the like are comprehensively controlled by a single ECU. However, the engine ECU, the motor ECU, the hybrid ECU that controls the engine ECU and the motor ECU, the automatic transmission ECU, etc. You may comprise by this ECU.

1 is a configuration diagram of a hybrid vehicle equipped with an ECU according to the present embodiment. FIG. 3 is a first map showing a provisional assist amount corresponding to the vehicle speed and SOC held by the ECU of FIG. 1. FIG. FIG. 2 is a diagram illustrating a state when an accelerator pedal is turned on from an off state in the hybrid vehicle of FIG. 1, (a) is a diagram illustrating motor power, and (b) is a diagram illustrating an on / off state of an accelerator pedal. FIG. 8C is a diagram showing an on / off state of the lockup clutch. FIG. 3 is a second map showing an estimated SOC corresponding to an estimated amount of motor consumption energy held by the ECU of FIG. 1. FIG. FIG. 6 is a third map showing an estimated slip ratio according to a provisional assist amount and a road surface friction coefficient held by the ECU of FIG. 1. FIG. 6 is a fourth map showing the final assist amount corresponding to the estimated slip ratio held by the ECU of FIG. 1. FIG. It is a figure which shows the vehicle speed holding | maintenance control in ECU of FIG. 1, (a) is a figure which shows the on / off state of an accelerator pedal, (b) is a figure which shows a vehicle speed. It is a figure which shows the deceleration variable control in ECU of FIG. 1, (a) is a figure which shows the on / off state of an accelerator pedal, (b) is a figure which shows a vehicle speed. FIG. 2 is a diagram illustrating a state when the motor assist mode is changed to a regeneration mode in the hybrid vehicle of FIG. 1, (a) is a diagram illustrating an on / off state of an accelerator pedal, and (b) is an on / off state of a brake pedal. It is a figure which shows an OFF state, (c) is a figure which shows the change of the hydraulic pressure of a master cylinder, (d) is a figure which shows a vehicle speed. It is a flowchart which shows the steady driving assistance control in ECU of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Hybrid vehicle, 2 ... Engine, 2a ... Electronically controlled fuel injection device, 3 ... Motor generator, 4 ... Automatic transmission, 4a ... Lock-up clutch, 5 ... Propeller shaft, 6 ... Rear differential, 7, 10 ... Drive Shaft, 8 ... pulley, 9 ... generator, 11 ... ECU, 12 ... inverter, 13 ... high voltage battery, 14 ... DC-DC converter, 15 ... 12V battery, 16 ... accelerator pedal, 17 ... brake pedal, 20 ... laser radar Sensor, 21 ... Accelerator pedal stroke sensor, 22 ... Wheel speed sensor, 23 ... SOC sensor, 24 ... Current sensor, 25 ... Brake pedal stroke sensor

Claims (3)

A vehicle travel control device for controlling a travel state in a hybrid vehicle including an engine and a motor,
An accelerator pedal detecting means for detecting that the accelerator pedal is turned off;
Vehicle speed control means for controlling the vehicle speed so as to maintain the vehicle speed of the hybrid vehicle or reduce the deceleration when it is detected by the accelerator pedal detection means that the accelerator pedal is turned off ;
Fuel cut control means for stopping the supply of fuel to the engine when the vehicle speed is controlled by the vehicle speed control means;
An acceleration request detecting means for detecting a driver's acceleration request;
Restarting means for restarting fuel supply to the engine when the acceleration request detection means detects a driver's acceleration request when fuel supply to the engine is stopped by the fuel cut control means ;
Increasing the amount of torque assist when restarting the engine by the motor when restarting fuel supply to the engine by the restarting means,
The vehicle speed control by the speed control means have lines by the torque assist of the motor,
When the vehicle speed is controlled by the vehicle speed control means, the torque assist amount at the time of vehicle speed control by the motor is required for assisting the engine at the time of restarting the engine when the fuel supply to the engine is restarted by the restart means. A vehicle travel control device, which is set based on a charge amount of a battery obtained by subtracting estimated power . A vehicle travel control device for controlling a travel state in a hybrid vehicle including an engine and a motor,
An accelerator pedal detecting means for detecting that the accelerator pedal is turned off;
Vehicle speed control means for controlling the vehicle speed so as to maintain the vehicle speed of the hybrid vehicle or reduce the deceleration when it is detected by the accelerator pedal detection means that the accelerator pedal is turned off,
The vehicle speed control by the speed control means have lines by the torque assist of the motor,
The vehicle travel control device is characterized in that the vehicle speed control means selects one of a vehicle speed holding control and a deceleration control based on a predetermined deceleration based on a charge amount of a battery . 3. The vehicle travel control according to claim 2 , wherein the predetermined deceleration is set such that a decrease in vehicle speed is suppressed as compared with a case where vehicle speed control by the vehicle speed control means is not performed. apparatus.

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