Vehicle control device

Abstract

Vehicle control device, comprising: an internal combustion engine (11) installed in a vehicle (10), a power generating device (13) for generating electricity using the power of the internal combustion engine (11), a battery (14) for storing the electricity generated by the power generating device (13), an electric starter motor (12) designed to rotate in order to start the internal combustion engine (11) when it is supplied with electricity from the battery (14), an electric power steering device (25) comprising an electric steering motor (36) configured to rotate in order to change the steering angles of steered wheels (15FL, 15FR) of the vehicle (10) when it is supplied with electricity from the battery (14); and a control unit (50, 55) designed such that it a voltage is supplied to the steering motor (36) using the electricity from the battery (14) to rotate the steering motor (36); stops the operation of the internal combustion engine (11) which is in an operating state when a previously defined stop condition is met; the starter motor (12) turns to restart the internal combustion engine (11), which is in an operating stop state, when a previously defined restart condition is met; and a required voltage (Vr) is calculated, which is the voltage needed to turn the steering motor to produce a previously determined output power; wherein the control unit (50, 55) is further designed to to be able to stop the internal combustion engine (11) when the required voltage (Vr) is at most as large as a first voltage value (Vmins) while the stopping condition is met; to be unable to stop the internal combustion engine (11) if the required voltage (Vr) is greater than the first voltage value (Vmins) while the stop condition is met; to be able to restart the internal combustion engine (11) when the required voltage (Vr) is at most as large as a second voltage value (Vminrs) that is smaller than the first voltage value (Vmins) while the restart condition is met; and to be unable to restart the internal combustion engine (11) if the required voltage (Vr) is greater than the second voltage value (Vminrs) while the restart condition is met.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

[0001] The present invention relates to a vehicle control device for controlling a vehicle which is equipped with an electric power steering device and is capable of performing a start-stop control. 2. Description of the state of the art

[0002] A vehicle disclosed in JP 2015-93522A is equipped with an electric power steering device. As is generally known, the power steering device is connected to a steering wheel. Furthermore, the power steering device is equipped with an electric steering motor. When electricity is supplied to the steering motor from a battery mounted in the vehicle, an output shaft of the steering motor rotates. The output shaft of the steering motor is connected to the steered wheels of the vehicle via a power transmission mechanism. Thus, when electricity is supplied to the steering motor, the steering angles of the steered wheels and the steering angle of the vehicle's steering wheel change.

[0003] A control device installed in this vehicle can operate an internal combustion engine under a start-stop control (hereinafter referred to as start-stop control).

[0004] In JP 2015-93522A, the start-stop control is activated when a predefined condition is met. Specifically, if a predefined stop condition is met while the internal combustion engine is in an operating state, the control device stops the engine. More precisely, the control device stops the engine if, for example, the steering torque, steering angle, or steering angle speed of the steering wheel, in a state where the vehicle speed is not greater than a predefined speed, does not exceed a stop threshold, which represents the stop condition. Conversely, if a predefined restart condition is met while the internal combustion engine is in an operating stop state, the control device restarts the engine.More precisely, the control device restarts the combustion engine if, for example, the steering torque, steering angle or steering angle speed exceeds a restart threshold, which represents the restart condition, in a state where the amount of actuation of an accelerator pedal is greater than zero.

[0005] Furthermore, the control device can perform a SHA (Lane Keeping Assist) control to automatically change the steering angle of the vehicle's steered wheels so that the vehicle travels along a lane in which it is traveling.

[0006] This means that, for example, if a camera mounted in the vehicle captures an image of a lane (a white line) painted on the lane the vehicle is traveling in, the control unit calculates a target steering path. This path is used to guide the vehicle along the lane based on the image data (capture data). Furthermore, the control unit controls the electric power steering system so that the vehicle travels along this target steering path. Specifically, the control unit supplies power from the battery to the steering motor. The electric power steering system then adjusts the steering angle (the turning angle of the steered wheels), thus ensuring the vehicle travels along the target steering path.

[0007] Furthermore, the stop threshold and restart threshold in this vehicle are set as variable values. This means that when the control device executes the SHA (Self-Activating Assistance) command, the stop threshold will be higher than when the SHA command is not executed. Similarly, when the control device executes the SHA command, the restart threshold will also be higher than when the SHA command is not executed.

[0008] Therefore, if the control device executes the SHA control, the internal combustion engine is easier to stop under the StSt control than if the SHA control is not executed. Furthermore, if the SHA control is executed, the internal combustion engine is more difficult to restart under the StSt control than if the SHA control is not executed.

[0009] JP 2014-156 242 A discloses a vehicle control device comprising an engine, a starting device for starting the engine, and a power steering device for generating assist torque, wherein engine stop control is permitted in a state where the engine is not stopped, and engine stop control is prohibited when the vehicle is in a right-hand turn or changing lanes. WO 2015 / 087 613 A1 discloses an automatic engine stop control device in which the engine does not restart if the driver begins to steer sharply. BRIEF SUMMARY OF THE INVENTION

[0010] As is generally known, when the internal combustion engine is running, an alternator, which is driven by the engine's rotation, generates electricity, and this electricity is stored (charged) in the battery. However, when the engine is stopped, the alternator does not generate any electricity. Therefore, when the engine is stopped, the battery voltage is generally lower than when the engine is running.

[0011] When an internal combustion engine that is off is restarted, a starter motor rotates thanks to the electricity supplied by the battery. Therefore, when the engine is restarted, the battery voltage is generally even lower than when the engine is off.

[0012] Therefore, if the control device supplies battery power to the steering motor of the electric power steering system while the combustion engine is stopped, the steering motor may not be able to generate the desired output power. Conversely, if the control device supplies battery power to the steering motor while the combustion engine is restarting, the steering motor may not be able to generate the desired output power.

[0013] Therefore, if, for example, the control device stops or restarts the internal combustion engine under the StSt control while the SHA control is in operation, there is a possibility that the steering angle of the steering wheel, which is changed by the steering motor, may temporarily become smaller than a desired steering angle.

[0014] The present invention is based on the solution of the problems described above and aims to provide a vehicle control device that is able to reduce the possibility that an electric steering motor of an electric power steering device may not be able to generate the desired output power because the internal combustion engine is subject to the StSt control.

[0015] To fulfill this objective, the StSt control device of the present invention comprises the following: an internal combustion engine installed in a vehicle, a power generating device for producing electricity using the power of the internal combustion engine, a battery for storing the electricity generated by the power generating device, an electric starter motor designed to rotate in order to start the internal combustion engine when it is supplied with electricity from the battery, an electric power steering device comprising an electric steering motor designed to rotate in order to change the steering angles of the vehicle's steered wheels when electricity is supplied to it from the battery, and a control unit designed in such a way that it feeds a voltage into the steering motor using the electricity from the battery to turn the steering motor, stops the operation of the internal combustion engine, which is in an operating state, when a previously defined stop condition is met, the starter motor turns to restart the internal combustion engine, which is in an operating stop state, when a previously defined restart condition is met, and A required voltage is calculated, which is the voltage needed to turn the steering motor to generate a previously determined output power.

[0016] The control unit (50, 55) is further designed to to be able to stop the combustion engine when the required voltage is at most as high as a first voltage value, if the stopping condition is met, to be unable to stop the combustion engine if the required voltage is greater than the first voltage value, if the stop condition is met, to be able to restart the internal combustion engine when the required voltage is at most as high as a second voltage value that is lower than the first voltage value, while the restart condition is met, and to be unable to restart the combustion engine if the required voltage is greater than the second voltage value while the restart condition is met.

[0017] The start / stop control device of the present invention can stop the internal combustion engine if the required voltage is at most equal to the first voltage value, provided the stop condition is met, and cannot stop the internal combustion engine if the required voltage is greater than the first voltage value, provided the stop condition is met. Furthermore, the start / stop control device can restart the internal combustion engine if the required voltage is at most equal to the second voltage value, which is less than the first voltage value, while the restart condition is met, and cannot restart the internal combustion engine if the required voltage is greater than the second voltage value while the restart condition is met.

[0018] Therefore, the steering motor is able to generate the desired output power even when a stop operation of the internal combustion engine under the StSt control system and a steering operation of the steered wheels by the electric power steering system are performed simultaneously. Similarly, the steering motor is able to generate the desired output power even when a restart operation of the internal combustion engine under the StSt control system and a steering operation of the steered wheels by the electric power steering system are performed simultaneously. Thus, the steering angles of the steered wheels, which are changed by the steering motor, do not become smaller than the desired angles, and the driver of the vehicle does not experience any discomfort when the internal combustion engine is operating under the StSt control system.

[0019] In one aspect of the present invention, the control unit is configured to calculate a vehicle target steering path, which is a vehicle steering path of the vehicle when a previously defined period of time (Trs) has elapsed, and to calculate the required voltage when the previously specified period has elapsed, so that the vehicle travels along the intended vehicle steering path.

[0020] In one aspect of the present invention, the steering motor control device calculates the required voltage a predetermined time later, so that the vehicle travels along the desired vehicle steering path calculated by the vehicle steering path calculation device. Thus, the vehicle travels along the desired vehicle steering path even when the driver is not operating the steering wheel.

[0021] Since there is a concern that the driver will not pay enough attention to the steering wheel while the vehicle is in motion, it is likely that the driver will experience severe discomfort if the steering motor does not produce the desired output power.

[0022] However, since the steering motor generates the desired output power even if the driver no longer pays sufficient attention to the steering wheel while the vehicle is in motion, the driver does not experience any significant discomfort.

[0023] In one aspect of the present invention, the control unit is configured to calculate a required power-stroke completion time voltage, which is the voltage required at a complete power-stroke completion time. The complete power-stroke completion time is the time during which a complete power cycle in the internal combustion engine is presumably completed when the starter motor is started at a predetermined time. The complete power-stroke completion time is the time at which a predetermined required starting time has elapsed since the predetermined time.

[0024] The starter control device is designed to start the starter motor at the previously specified time when the required working cycle completion time voltage is at most as large as the second voltage value.

[0025] When the internal combustion engine is restarted, it is necessary to operate the starter motor to initiate a first working stroke in the internal combustion engine, and to continue turning the starter motor until a complete working stroke is performed in the internal combustion engine.

[0026] Therefore, if the starter control device is designed such that it can start the starter motor at the completion time of the full power cycle, provided the required power cycle completion voltage is not greater than the second voltage value, then the starter motor will rotate immediately after the completion time of the full power cycle. Thus, the required voltage immediately after the completion time of the full power cycle can be greater than the second voltage value. Or, put another way, the steering motor may not be able to generate the desired output power immediately after the completion time of the full power cycle.

[0027] However, if the present invention is implemented in this manner, the starter motor will only rotate after the completion of the full power stroke. Therefore, the probability is lower that the required voltage will be greater than the second voltage value immediately after the completion of the full power stroke.

[0028] In one aspect of the present invention, the control unit is configured to calculate the required voltage when a previously defined electricity suppression condition is met, such that the required voltage when the previously defined electricity suppression condition is met is smaller than the required voltage calculated when the previously defined electricity suppression condition is not met.

[0029] In one aspect of the present invention, when the electrical suppression condition is met, the required voltage is lower than when the electrical suppression condition is not met. Therefore, when the electrical suppression condition is met, the electric power steering device can be operated with a lower voltage.

[0030] In the above description, references to the elements of the present invention, which are used in the following descriptions of embodiments, have been added in parentheses for the sake of clarity. However, these references must not be used to limit the scope of the present invention.

[0031] Other problems, other features and associated advantages of the present invention will be easily understood by reference to the description of embodiments of the present invention, which is now given with reference to the following drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic top view of a complete vehicle comprising a vehicle control device according to an embodiment of the present invention. Fig. Figure 2 is a top view showing a state in which the vehicle is driving on a road. Fig. Figure 3 is a time diagram showing a curvature of the road, a limiting speed of the vehicle, a target steering angle, a target steering angle speed, a required torque of a steering motor, and a state of the steering control system. Fig. Figure 4 is a curve diagram showing a relationship between the required voltage of a battery, the required torque of the steering motor, and the target steering angle speed. Fig. Figure 5 is a flowchart showing a processing operation performed by a steering control ECU. Fig. Figure 6 is a flowchart showing a processing operation performed by a Required Voltage Monitoring ECU. Fig. Figure 7 is a flowchart showing a processing operation performed by the Required Voltage Monitoring ECU. Fig. Figure 8 is a flowchart showing a processing operation performed by an engine control ECU. Fig. Figure 9 is a flowchart showing a processing operation performed by the engine control ECU. Fig. 10 is a flowchart of a first modified embodiment of the present invention according to Fig. 5. DETAILED DESCRIPTION OF PREFERRED EXECUTION FORMS

[0032] Furthermore, a vehicle 10 according to an embodiment of the present invention is described with reference to the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8 to Fig. 9 described.

[0033] First, the overall structure of vehicle 10 is described with reference to Fig. 1 described.

[0034] Vehicle 10 is equipped with a control unit 50. The control unit 50 comprises an engine control ECU 51, a vehicle control ECU 52, a brake control ECU 53, a camera control ECU 54, a steering control ECU 55, and a required voltage monitoring ECU 56. ECU is the abbreviation for "Electric Control Unit." The ECU is equipped with a microcomputer that includes a storage device such as a CPU, ROM, and RAM. The CPU performs various functions by executing instructions (programs) stored in the ROM.Furthermore, the engine control ECU 51, the vehicle control ECU 52, the brake control ECU 53, the camera control ECU 54, the steering control ECU 55 and the required voltage monitoring ECU 56 are interconnected in such a way that they are able to send and receive various control information and request signals to each other via a CAN (Controller Area Network).

[0035] The vehicle 10 is equipped with an internal combustion engine 11 (hereinafter referred to as engine 11). The engine 11 combusts an air-fuel mixture of air and fuel (for example, gasoline) that has been injected from an injector (not shown) into a combustion chamber of a cylinder. When a piston moves up and down in the cylinder in time with the combustion, a crankshaft (not shown) is rotated, and the engine 11 is put into an operating state.

[0036] The engine 11 is equipped with a starter motor 12 and an alternator 13.

[0037] As is generally known, to start the engine 11, the ignition of the vehicle 10 (not shown) is switched from OFF to ON by turning an ignition key (not shown). Then, electricity (electric current) from a battery 14 is supplied to the starter motor 12, and the starter motor 12 is started. A first power stroke is then performed in the engine 11, and the crankshaft is turned. When the number of revolutions of the crankshaft reaches at least a previously determined number, the engine control ECU 51 determines that a complete power stroke has been performed (completed) in the engine 11 and stops the starter motor 12.

[0038] The time from the starting of the starter motor 12 until a complete power cycle of the motor 11 is not constant. However, the motor 11 is designed so that the complete power cycle is executed (completed) until a predetermined starting time Trs has elapsed since the starting of the starter motor 12, provided there is no operational fault. The starting time Trs is recorded in a memory device of the engine control ECU 51. It should be noted that the starting time Trs is, for example, 5 seconds.

[0039] Furthermore, when the engine 11 is in operation, the rotational force of the crankshaft is transmitted to the alternator 13 via a belt (not shown). The alternator 13 then generates electricity. The electricity generated by the alternator 13 is stored in the battery 14.

[0040] The electricity stored in battery 14 is fed into the control unit 50. The voltage of the electricity stored in battery 14 is constantly detected (monitored) by the required voltage monitoring ECU 56. Furthermore, the control unit 50 controls battery 14 so that the electricity from battery 14 is directed to various electronic devices of the vehicle 10. These electronic devices include a brake actuator, a special motion state quantity sensor (which differs from sensors 16, 17, 18, which will be described later), an air conditioning system, a liquid crystal field and a motor for driving the sliding window, all of which are not shown, in addition to a yaw rate sensor 16, a wheel speed sensor 17, a brake actuation amount sensor 18, a camera 20, turn signals 22L and 22R, a steering torque sensor 35, a steering motor 36 and a steering angle sensor 37.

[0041] An accelerator pedal actuation sensor 19 is connected to the engine control ECU 51. The accelerator pedal actuation sensor 19 detects an actuation amount AP of the accelerator pedal A / P (Acceleration Pedal) and outputs a signal representing the actuation amount AP to the engine control ECU 51. Furthermore, a throttle actuator (not shown) of the engine 11 is connected to the engine control ECU 51. The engine control ECU 51 controls the throttle actuator according to a signal representing the received actuation amount AP. The throttle actuator changes the opening degree of a throttle valve by actuating the throttle valve located in the intake manifold of the engine 11. That is, the opening degree of the throttle valve changes according to the actuation amount AP. When the degree of opening of the throttle valve changes, the amount of air drawn into the engine 11 changes in order to change the amount of fuel injected into the engine 11.As a result, the torque of engine 11 changes.

[0042] A suspension (not shown) is arranged in the front section of a vehicle body 10A of vehicle 10. Each of the carriers (kingpins) is supported between each of the distal ends of the left and right upper arms and each of the distal ends of the left and right lower arms, such that they are rotatable about a corresponding kingpin axis. The carriers, the upper arms, and the lower arms are components of the suspension. Furthermore, the left and right carriers support a pair of left and right front wheels 15FL, 15FR, respectively, such that they are rotatable about a corresponding horizontal axis.

[0043] A pair of left and right rear wheels 15RL and 15RR are supported on the rear section of the vehicle 10 in such a way that they can rotate about a horizontal axis.

[0044] The yaw rate sensor 16 for detecting the yaw rate of the vehicle 10 is located in the vehicle body 10A. The yaw rate sensor 16 is operated by means of electricity supplied by the battery 14.

[0045] Furthermore, wheel speed sensors 17 (of which only one wheel speed sensor 17 is in Fig. (as shown in Figure 1), each corresponding to a wheel, is arranged on four sections of the vehicle body 10A. Each of the wheel speed sensors 17 is operated by means of electricity supplied by the battery 14.

[0046] The yaw rate sensor 16 and the wheel speed sensors 17 are connected to the vehicle control ECU 52. The vehicle control ECU 52 receives the detection signal from the yaw rate sensor 16 and the detection signals from the wheel speed sensors 17.

[0047] The vehicle control ECU 52 detects the vehicle speed V of the vehicle 10 based on the detection value of each wheel speed sensor 17.

[0048] Vehicle 10 is equipped with a brake pedal B / P and the brake actuation force sensor 18. The brake actuation force sensor 18 is operated by means of electricity supplied by the battery 14.

[0049] The brake actuation amount sensor 18 detects an actuation amount BP of the brake pedal B / P and outputs a signal representing the actuation amount BP to the brake control ECU 53.

[0050] Furthermore, a brake actuator (not shown) is connected to the brake control ECU 53. The brake actuator is located in a hydraulic circuit between a master brake cylinder, which pressurizes the hydraulic fluid by means of a depressurization force from the brake pedal B / P, and a friction brake mechanism located in each wheel. The friction brake mechanism presses a brake pad of each wheel against a corresponding brake disc to generate a hydraulic braking force by actuating a wheel brake cylinder using hydraulic pressure from the hydraulic fluid supplied by the brake actuator. The brake actuator is a generally known actuator for adjusting the pressure of the hydraulic fluid supplied to the wheel brake cylinders and delivers the hydraulic pressure to each of the wheel brake cylinders according to a command from the brake control ECU 53 to generate braking forces at each of the wheels.

[0051] The brake actuator includes an electric pump and several solenoid valves and is operated by means of electricity supplied by battery 14.

[0052] The brake control ECU 53 actuates the brake actuator based on the brake actuation amount BP detected by the brake actuation amount sensor 18 and an operating state amount detected by the vehicle's (not shown) special motion state quantity sensor(s) 10. When the brake actuator is actuated, a braking force is applied to each wheel, thus decelerating the vehicle 10.

[0053] Vehicle 10 is equipped with camera 20, which is controlled by camera control ECU 54. Camera 20 is powered by electricity supplied by battery 14. Inside vehicle 10, camera 20 is positioned directly behind a windshield (not shown). Camera 20 is a stereo camera. Camera 20 captures an image of an object (for example, a vehicle and a pedestrian) located in front of the windshield.

[0054] The image display data (the recording data) from camera 20 are transmitted to the camera control ECU 54. The camera control ECU 54 specifies the type of object (or objects) in the image display data using a pattern matching process that utilizes the image display data captured by camera 20.

[0055] Furthermore, the camera displays 20 left and right white lines (lane markings) on a road on which vehicle 10 is driving. Additionally, the camera control ECU 54 calculates the shape of the road and the positional relationship between the road and vehicle 10 based on the displayed white lines.

[0056] Vehicle 10 is equipped with an electric power steering device 25.

[0057] The electric power steering device 25 is provided with a rack 26, which is a rod-like element extending laterally (to the left and right). The rack 26 is laterally displaceable with respect to the vehicle body 10A and cannot rotate about its own axis. A helical thread is formed in the outer circumferential surface of the rack 26.

[0058] An inner end section of each of a pair of left and right tie rods 27 is connected to a corresponding left and right end section of the rack 26, and an outer end section of each of the left and right tie rods 27 is connected to a corresponding left and right support.

[0059] A pinion shaft 28 engages with the rack 26 (the screw thread).

[0060] One end (the lower end) of a steering shaft 30, which is a rod-like element, is connected to the pinion shaft 28 via a universal joint 31.

[0061] Furthermore, a steering wheel 32 is attached to the other end (the upper end) of the steering shaft 30.

[0062] When the steering wheel 32 is turned, this rotational force is transmitted via the steering shaft 30 and the universal joint 31 to the pinion shaft 28, and then the pinion shaft 28 is rotated about its own axis. Since the rack 26, which is engaged with the pinion shaft 28, is displaced in one of the lateral directions, the steering angle of the front wheels 15FL, 15FR, which are connected to the rack 26 via the tie rods 27, and of the support, changes.

[0063] The intermediate section of the steering shaft 30 is formed by a torsion bar 33. The steering torque sensor 35, for detecting a steering torque Tr of the steering shaft 30 based on a torsion angle of the torsion bar 33 about its own axis, is arranged close to the torsion bar 33. The steering torque sensor 35 can, for example, be formed by a resolver.

[0064] Therefore, when the steering shaft 30 is rotated, the steering torque sensor 35 detects the steering torque Tr of the steering shaft 30.

[0065] Furthermore, the electric power steering device 25 is equipped with the steering motor 36, which is a DC electric motor. The steering motor 36 is connected to the rack 26 (the helical gear) via a reduction mechanism (not shown).

[0066] Furthermore, the steering angle sensor 37 is arranged around the steering shaft 30 to detect a steering angle MA, which is a rotation angle of the steering shaft 30 (of the steering wheel 32).

[0067] The steering torque sensor 35, the steering motor 36 and the steering angle sensor 37 are connected to the steering control ECU 55.

[0068] When the steering wheel 32 is operated by a driver of the vehicle 10, the steering control ECU 55 calculates a target power steering torque by applying a steering torque Tr detected by the steering torque sensor 35 and the vehicle speed V calculated by the vehicle control ECU 52 to a target power steering torque calculation map (lookup table) stored in the memory device of the steering control ECU 55. Furthermore, the steering control ECU 55 controls the steering motor 36 such that the output shaft of the steering motor 36 delivers the target power steering torque. As a result, the torque generated by the steering motor 36 is transmitted to the rack 26 in such a way that power steering is provided when the steering wheel 32 is turned by the driver.

[0069] Furthermore, the vehicle 10 is equipped with a steering wheel support section (not shown) that rotatably supports the steering wheel 32. A turn signal lever 21 is supported on the side surface of the steering wheel support section so that it can rotate in a vertical direction (up and down). Additionally, a pair of left and right turn signals 22L, 22R are arranged on the front of the vehicle 10.

[0070] The indicator lever 21 and the indicators 22L, 22R are connected to the vehicle control ECU 52.

[0071] When the turn signal lever 21 is turned upwards from its first position, the vehicle control ECU 52 supplies power from battery 14 to the left turn signal 22L to cause the indicator light 22L to flash. Conversely, when the turn signal lever 21 is turned downwards from its first position, the vehicle control ECU 52 supplies power from battery 14 to the right turn signal 22R to cause the indicator light 22R to flash.

[0072] The engine control ECU 51 according to the present embodiment is capable of operating the engine 11 under StSt control.

[0073] This means that if a predefined stop condition is met while the engine 11 is in operation, the engine control ECU 51 stops the fuel supply to the engine 11 to temporarily stop the engine 11. For example, if a condition in which the vehicle speed V of the vehicle 10 is not greater than a predefined speed (for example, a maximum of 10 km / h) and the accelerator pedal actuation amount AP A / P (Acceleration Pedal) is zero is maintained for a predefined period of time, then the stop condition is met.

[0074] Furthermore, if a predefined restart condition is met during the temporary stop state, the engine control ECU 51 starts the starter motor 12 to restart the engine 11. For example, if a state in which the amount of actuation AP of the accelerator pedal A / P (Acceleration Pedal) is greater than zero is maintained for a predefined period of time, the restart condition is met.

[0075] In this way, the engine control ECU 51 executes the StSt control when the vehicle 10 is stopped and when the vehicle 10 is moving.

[0076] Furthermore, the control device 50 can perform automatic drive support control and collision avoidance control.

[0077] The automatic drive assist control and the collision avoidance control are executed when an automatic drive assist mode is selected by actuating an automatic drive assist mode selector switch 60, which is located inside the vehicle 10 (for example, on an instrument panel). The automatic drive assist mode selector switch 60 is connected to the control device 50.

[0078] First, the automatic drive support control is described.

[0079] Fig. Figure 2 shows a state in which vehicle 10 is traveling in automatic drive assist mode on road 70. White lines 70A, 70B, 70C (lane markings) are painted on both side sections of road 70 and on the median section of road 70, each in the width direction. White line 70B is a median line. That is, road 70 has two lanes 71 and 72. Vehicle 10 is traveling in lane 71 in the direction of arrow A. Conversely, a vehicle (not shown), which is not vehicle 10, is traveling in lane 72 in the opposite direction to arrow A.

[0080] A road 80, distinct from road 70, is connected to lane 72 of road 70. White lines 80A, 80B, and 80C (lane markings) are painted on both outer edges and on the center of road 80, each in the width direction. White line 80B is a median line. This means that road 80 has two lanes, 81 and 82. Vehicle 10 can travel in lane 81 in the direction indicated by arrow B. Conversely, a vehicle (not shown), other than vehicle 10, travels in lane 82 in the opposite direction to arrow B.

[0081] The steering control ECU 55 receives image representation data, mapped by camera 20, from the camera control ECU 54. This image representation data includes image representation data of white line 70A and image representation data of white line 70B. The steering control ECU 55 calculates a vehicle desired steering path Prp of a front section Fp, which is a section of road 70, based on the image representation data of white line 70A and the image representation data of white line 70B. For example, the steering control ECU 55 calculates a path passing through the midpoint of lane 71 (i.e., the midpoint of the area between the left white line 70A and the right white line 70B) in the latitude direction as the vehicle desired steering path Prp.

[0082] Five front sections Fp are in Fig. Figure 2 shows that the forward sections Fp comprise Fp1, Fp2, Fp3, Fp4, and Fp5. Each forward section Fp is a segment of road 70 along which vehicle 10 travels after a predetermined time has elapsed to start Trs. That is, each forward section Fp is separated from the instantaneous position of vehicle 10 by a forward separation distance Lpf, which is a value obtained by multiplying the vehicle speed V of vehicle 10 at the predetermined time by the required time Trs.

[0083] The front end of each front section Fp corresponds to the front end position of vehicle 10, the time required to start Trs later. Similarly, the rear end of each front section Fp corresponds to the rear end position of vehicle 10, the time required to start Trs later.

[0084] The front section Fp1 is separated forward by the forward separation distance Lpf from the position of vehicle 10 at the current time.

[0085] The front section Fp2 is separated forward from the position of the vehicle 10 by the forward separation distance Lpf at a time that is a previously defined calculation interval time Tc back from the current time. The calculation interval time Tc represents a calculation interval for calculating the vehicle's target steering path Prp, a curvature ρ, a target steering angle θ*, a target steering angular velocity θd*, a limiting velocity V*, a required torque Trq (a required output power Opra), and a required voltage Vr by the steering control ECU 55. The curvature ρ, the target steering angle θ*, the target steering angular velocity θd*, the limiting velocity V*, the required torque Trq (the required output power Opra), and the required voltage Vr are described later. The calculation interval time Tc according to the present embodiment is set to 1 / 5 of the time required to start Trs.

[0086] Similarly, the front section Fp3 is separated forward from the position of vehicle 10 by the forward separation distance Lpf at a time that is a predetermined period twice the predetermined calculation interval time Tc, in time from the current time. Similarly, the front section Fp4 is separated forward from the position of vehicle 10 by the forward separation distance Lpf at a time that is a predetermined period three times the predetermined calculation interval time Tc, in time from the current time. Similarly, the front section Fp5 is separated forward from the position of vehicle 10 by the forward separation distance Lpf at a time that is a predetermined period four times the predetermined calculation interval time Tc, in time from the current time.

[0087] Furthermore, the steering control ECU 55 calculates the curvature ρ of the front section Fp based on the vehicle's target steering path Prp.

[0088] Furthermore, the steering control ECU 55 calculates the target steering angle θ*, which corresponds to the front section Fp, based on the calculated curvature ρ. Or, put another way: the steering control ECU 55 calculates the target steering angle θ* and the time required to start Trs later. That is, the steering control ECU 55 calculates the target steering angle θ* and the time required to start Trs later to position the vehicle 10 on the vehicle target steering path Prp of the front section Fp, based on the curvature ρ, which corresponds to the front section Fp.

[0089] Furthermore, the steering control ECU 55 calculates the target steering angle speed θd* and the time required to start Trs later by differentiating the target steering angle θ* with respect to time.

[0090] Furthermore, the steering control ECU 55 calculates the limiting speed V*, which is a limit (upper limit) of the vehicle speed V and corresponds to the front section Fp, based on the target steering angle θ*, the time required to start Trs later, and the limit of the lateral acceleration. Or, put another way: the steering control ECU 55 calculates the limiting speed V* and the time required to start Trs later.

[0091] Furthermore, the steering control ECU 55 calculates the required torque Trq (output torque), which is a torque that is to be output by the steering motor 36 the required time to start Trs later, on the basis of the target steering angle θ* the required time to start Trs later and the limiting speed V* the required time to start Trs later.

[0092] For example, the required torque Trq (recovery torque) can be calculated by applying a target steering angle θ* (steering angle) and the limiting speed V* (vehicle speed) to the following expression (1). Trq=(θ*,V*)=2ζKf(β+1f×γ / V*−θ*) ζ: Wake [m] Kf: Cornering power at the front [N / wheel] β: Vehicle body slip angle [rad] lf: Front-to-rear distance between the front axle and the vehicle's center of gravity γ: Yaw rate [rad / s]

[0093] It should be noted that a method for calculating the required torque Trq of the steering motor 36 on the basis of the target steering angle θ* (steering angle) and the limiting speed V* (vehicle speed) is generally known and is described, for example, in “Motion and Control of Automobile” (Publisher: Sankaido Co. Ltd., Author: Masato Abe, Publication date of the first edition: July 10, 1992).

[0094] Furthermore, the steering control ECU 55 multiplies the required torque Trq and the required time to start Trs later by the target steering angle speed θd* to calculate the required output power Opra, which is to be output by the steering motor 36, the required time to start Trs later.

[0095] Furthermore, a specific relationship exists between the output torque (required torque Trq) of the steering motor 36, which is a DC motor, the applied voltage supplied to the steering motor 36, and the angular velocity of the output shaft of the steering motor 36. Moreover, the angular velocity of the output shaft is proportional to the steering angular velocity (target steering angular velocity θd*) of the steering wheel 32. Therefore, the required voltage Vr, which is the voltage value to be applied to the steering motor 36, can be calculated based on the required torque Trq of the steering motor 36 and the target steering angular velocity θd*. Or, in other words, the required voltage Vr can be calculated based on the required output power Opra.

[0096] In this embodiment, the required torque Trq of the steering motor 36 and the target steering angular velocity θd* of the steering wheel 32 are used as arguments (parameters), and a required voltage calculation map (lookup table), which can calculate the required voltage Vr using the two arguments, is stored in the memory device of the steering control ECU 55. Therefore, the steering control ECU 55 applies the required torque Trq and the required start time Trs, as well as the target steering angular velocity θd* and the required start time Trs, to this required voltage calculation map to calculate the required voltage Vr and the required start time Trs. The required voltage Vr is a voltage value that the steering control ECU 55 needs to control the steering motor 36 so that the steering angle of the steering wheel 32 corresponds to the target steering angle θ* the time required to start Trs later.

[0097] When the automatic drive assist mode is selected by the automatic drive assist mode selector switch 60, the steering control ECU 55 continuously supplies electricity from the battery 14 to the steering motor 36 while performing a general known current feedback control (PID control). The electric power steering device 25 is then operated by the output power of the steering motor 36.

[0098] In this case, if the voltage of battery 14 at the time when the required time to start Trs has elapsed from the current time is at least as high as the required voltage Vr at that time, the steering angle of the steering wheel 32 will later match the target steering angle θ*. Therefore, the vehicle 10 will travel along the vehicle target steering path Prp later.

[0099] Furthermore, the vehicle speed V of vehicle 10 is limited to a maximum of the limiting speed V* the time required to start Trs later.

[0100] For example, if the vehicle speed V is greater than the limit speed V* at the current time, the engine control ECU 51, which has received a signal from the steering control ECU 55, causes the throttle actuator to reduce the throttle valve opening, and / or the brake control ECU 53, which has received a signal from the steering control ECU 55, actuates the brake actuator. As a result, when the time required to start Trs has elapsed from the current time, the vehicle speed V of vehicle 10 will be a speed that is not greater than the limit speed V*.

[0101] If, however, the vehicle speed V is not greater than the limiting speed V* at the current time, the vehicle speed V is not controlled to calculate the required torque Trq. That is, in this case, the engine control ECU 51 does not control the throttle actuator, and the brake control ECU 53 does not actuate the brake actuator.

[0102] Each time the calculation interval time Tc has elapsed, the steering control ECU 55 repeatedly calculates the vehicle's target steering path Prp, the curvature ρ, the limiting speed V*, the target steering angle θ*, the target steering angle velocity θd*, the required output power Opra, and the required voltage Vr, all of which correspond to each of the front sections Fp. Furthermore, the steering control ECU 55 stores the calculated curvature ρ, the calculated limiting speed V*, the calculated target steering angle θ*, the calculated target steering angle velocity θd*, the calculated required output power Opra, and the calculated required voltage Vr in its memory device in a time-series manner.

[0103] Fig. Figure 3 shows a curve diagram representing an example of a relationship between the curvature ρ, the limiting speed V*, the target steering angle θ*, the target steering angular velocity θd*, the required torque Trq, and time. This curve diagram is created based on the curvature ρ, the limiting speed V*, the target steering angle θ*, the target steering angular velocity θd*, and the required torque Trq, all of which correspond to each of the front sections Fp. It should be noted that time t0 is instantaneous time.

[0104] As described above, when the engine control ECU 51, the brake control ECU 53 and the steering control ECU 55 are performing automatic drive assist control, the vehicle 10 will continue to travel on the road 70 along the vehicle's intended steering path Prp even if the driver does not operate the steering wheel 32, the accelerator pedal A / P and the brake pedal B / P.

[0105] Next, the collision avoidance control, which is implemented by the control device 50, will be described.

[0106] The collision avoidance control system includes a warning control, an automatic braking control, and an automatic steering control.

[0107] For example, if camera 20 captures an image of another vehicle (hereinafter referred to as a vehicle ahead) positioned in front of vehicle 10 and traveling in lane 71, the vehicle control ECU 52 calculates a collision prediction time KVZ, which is the predicted time until vehicle 10 collides with the vehicle ahead. Furthermore, if the vehicle control ECU 52 determines that the collision prediction time KVZ is at most as long as a first collision prediction time recorded in its memory device, the vehicle control ECU 52 activates a warning device located in vehicle 10. That is, the warning control is executed.

[0108] The collision prediction time (CPT) is calculated by the vehicle control ECU 52 based on the distance L between the vehicle ahead and vehicle 10 and the relative speed Vr of vehicle 10 with respect to the vehicle ahead. The relative speed Vr is calculated based on the image display data acquired by camera 20.

[0109] Furthermore, if the vehicle control ECU 52 determines that the collision prediction time KVZ is no longer than a second collision prediction time recorded in the memory device after the vehicle control ECU 52 has activated the warning device, then the brake control ECU 53 activates the brake actuator. Therefore, a friction braking force is applied by the friction braking mechanism to the front wheels 15FL, 15FR and the rear wheels 15RL, 15RR to reduce the vehicle speed V. That is, the automatic brake control is executed.

[0110] Furthermore, if the vehicle control ECU 52 determines that the vehicle 10 is likely to collide with the vehicle ahead after the brake control ECU 53 has activated the brake actuator, the steering control ECU 55 supplies the electricity from the battery 14 to the steering motor 36. The steering wheel 32 is then steered by the output power of the steering motor 36 in such a way that the vehicle 10 avoids a collision with the vehicle ahead. That is, the automatic steering control is executed.

[0111] Furthermore, the voltage of the battery 14 varies depending on the condition of the engine 11 and the condition of the electronic devices installed in the vehicle 10.

[0112] For example, if the electronic devices are activated simultaneously in a state where motor 11 is in a normal operating state (that is, in a state where motor 11 is running without turning the starter motor 12), the voltage of battery 14 will be approximately 14 V. That is, when motor 11 is in a normal operating state, the minimum voltage of battery 14 is approximately 14 V. Hereafter, this voltage value (14 V) will be referred to as the "normal operating time minimum voltage Vmind".

[0113] Furthermore, when the engine control ECU 51 stops the engine 11 under the start-stop control, the alternator 13's electricity generation operation is stopped. Therefore, if the states of the electronic devices are the same as when the engine 11 is in its normal operating state, the voltage of the battery 14 is lower than when the engine 11 is in its normal operating state. Thus, when the electronic devices are activated while the engine 11 is stopped, the voltage of the battery 14 will be approximately 12 V. That is, when the engine 11 is in the stop-start state, the minimum value of the battery 14 voltage is approximately 12 V. Hereinafter, this voltage value (12 V) is referred to as the "stop-time minimum voltage Vmins".

[0114] Furthermore, when the engine control ECU 51 restarts the engine 11 under the starter control using the starter motor 12, electricity from the battery 14 is supplied to the starter motor 12. Therefore, if the states of the electronic devices are the same as when the engine 11 is in the off state, the voltage of the battery 14 will be lower than when the engine 11 is in the off state. Thus, when the electronic devices are actuated while the starter motor 12 is turning, the voltage of the battery 14 will be approximately 8 V. That is, when the engine 11 is restarted, the minimum voltage of the battery 14 is approximately 8 V. This voltage value (8 V) will henceforth be referred to as the "restart time minimum voltage Vminrs".

[0115] As described above, the required voltage Vr of the steering motor 36 can be calculated using the required voltage calculation chart.

[0116] Fig. Figure 4 shows the relationship between the required voltage Vr (applied voltage) of the steering motor 36, the required torque Trq of the steering motor 36, and the absolute value of the target steering angular velocity θd* (steering angular velocity) of the steering wheel 32. This relationship is determined by the required voltage calculation chart. Or, put another way: Fig. Figure 4 shows the relationship between the required voltage Vr and the required output power Opra of the steering motor 36.

[0117] If the required output power Opra, which is determined by the required torque Trq of the steering motor 36 and the target steering angle velocity θd* of the steering wheel 32, lies on a straight line L1 in Fig. 4, which is the required voltage Vr of the steering motor 36 14 V and is equal to the normal operating minimum voltage Vmind. If furthermore, the required output power Opra lies on a straight line L2 in Fig. If position 4 is located, then the required voltage Vr of the steering motor is 36 12 V and equal to the minimum stop-time voltage Vmins. Furthermore, if the required output power Opra lies on a straight line L3 in Fig. If position 4 is located, then the required voltage Vr of the steering motor is 36.8 V and equal to the minimum restart time voltage Vminrs.

[0118] A straight broken line La of the curve diagram, which represents the required torque Trq in Fig. Figure 3 shows, representing the maximum value of the torque that the steering motor 36 can generate when the battery voltage is 14 14 V.

[0119] Similarly, a straight dashed line Lb represents the maximum value of the torque that the steering motor 36 can generate when the battery voltage is 14 12 V. Similarly, a straight dashed line Lc represents the maximum value of the torque that the steering motor 36 can generate when the battery voltage is 14 8 V.

[0120] For example, if the required voltage Vr, calculated by applying the required torque Trq of the steering motor 36 and the target steering angle speed θd* to the required voltage calculation chart, is no greater than 14 V while the motor 11 is in normal operating condition (that is, in the state where the voltage of battery 14 is at least as high as the normal operating time minimum voltage Vmind), the steering control ECU 55 can supply a voltage of at least the required voltage Vr to the steering motor 36. Or, put another way: if the required torque Trq is on the straight dashed line La or below the straight dashed line La in Fig. When the vehicle 10 is in position 3, while the motor 11 is in its normal operating state, the steering control ECU 55 can rotate the steering motor 36 at the target steering angle speed θd*. Or, in other words, the steering motor 36 can generate the required output power Opra. That is, in this case, the vehicle 10 can travel along the target vehicle steering path Prp under automatic drive assist control.

[0121] On the other hand, if, for example, the required voltage Vr of the steering motor 36 is higher than 14 V while the motor 11 is in its normal operating state, the steering control ECU 55 may not be able to supply a voltage of at least the required voltage Vr to the steering motor 36. Or, put another way: if the required torque Trq is above the straight dashed line La in Fig. If the steering control ECU 55 is positioned 3 while the motor 11 is in normal operating condition, then the steering control ECU 55 cannot rotate the steering motor 36 at the target steering angular velocity θd*. For example, if the voltage of the battery 14 is the normal operating minimum voltage Vmind (14 V) and the required voltage Vr of the steering motor 36 is higher than 14 V, then the steering control ECU 55 cannot rotate the steering motor 36 at the target steering angular velocity θd*.

[0122] In this case, the steering control ECU 55 applies the maximum suitable voltage (i.e., the battery voltage at that time), which is the maximum voltage that the battery 14 can supply to the steering motor 36. However, the maximum suitable voltage is lower than the required voltage Vr. Therefore, it may happen that the steering motor 36 is unable to turn the steering wheel 32 at the target steering angular velocity θd* while generating the required torque Trq. That is, in this case, the vehicle 10 does not travel along the target vehicle steering path Prp under the automatic drive assist control.

[0123] For example, if the battery voltage is 14 V and the required voltage Vr is 16 V, the steering control ECU 55 cannot supply a voltage of at least the required Vr to the steering motor 36. Therefore, in this case, the steering motor 36 cannot turn the steering wheel 32 at the target steering angular velocity θd* while generating the required torque Trq. That is, in this case, the vehicle 10 does not travel along the target vehicle steering path Prp under the automatic drive assist control.

[0124] For example, if the required voltage Vr, calculated by applying the required torque Trq of the steering motor 36 and the target steering angle speed θd* to the required voltage calculation chart, is no greater than 12 V while the motor 11 is in the operating stop state (that is, in the state where the voltage of the battery 14 is at least the minimum stop-time voltage Vmins), then the steering control ECU 55 can supply a voltage of at least the required voltage Vr to the steering motor 36. Or, put another way: if the required torque Trq is on the straight dashed line Lb or below the straight dashed line Lb in Fig. If the vehicle 10 is in position 3 while the motor 11 is in the operating stop state, the steering control ECU 55 can rotate the steering motor 36 at the target steering angle speed θd*. Or, in other words, the steering motor 36 can generate the required output power Opra. That is, in this case, the vehicle 10 can travel along the target vehicle steering path Prp under automatic drive support control.

[0125] On the other hand, if, for example, the required voltage Vr of the steering motor 36 is higher than 12 V while the motor 11 is in the operating stop state, the steering control ECU 55 cannot supply a voltage of at least the required voltage Vr to the steering motor 36. Or, put another way: if the required torque Trq is above the straight dashed line Lb in Fig. If position 3 is 3 while motor 11 is in the operating stop state, the steering control ECU 55 cannot rotate the steering motor 36 at the target steering angular velocity θd*. For example, if the voltage of battery 14 is the minimum stop-time voltage Vmins (12 V) and the required voltage Vr of the steering motor 36 is higher than 12 V, the steering control ECU 55 cannot rotate the steering motor 36 at the target steering angular velocity θd*.

[0126] In this case, the steering control ECU 55 feeds the maximum suitable voltage, which is the maximum voltage that battery 14 can supply, into the steering motor 36. However, the maximum suitable voltage is lower than the required voltage Vr. Therefore, the steering motor 36 cannot turn the steering wheel 32 at the target steering angular velocity θd* while generating the required torque Trq. That is, in this case, the vehicle 10 does not travel along the target vehicle steering path Prp under the automatic drive assist control.

[0127] For example, if the battery voltage is 12 V and the required voltage Vr is higher than 12 V, the steering control ECU 55 cannot supply a voltage of at least the required voltage Vr to the steering motor 36. Therefore, in this case, the steering motor 36 cannot turn the steering wheel 32 at the target steering angular velocity θd* while generating the required torque Trq. That is, in this case, the vehicle 10 does not travel along the target vehicle steering path Prp under automatic drive assist control.

[0128] Furthermore, if, for example, the required voltage Vr, calculated by applying the required torque Trq of the steering motor 36 and the target steering angle speed θd* to the required voltage calculation chart, is not greater than 8 V while the engine 11 is being restarted (that is, in the state where the starter motor 12 is turning), then the steering control ECU 55 can supply a voltage of at least the required voltage Vr to the steering motor 36. Or, put another way: if the required torque Trq lies on or below the straight dashed line Lc in Fig. If the vehicle is located at position 3 while the engine 11 is being restarted, the steering control ECU 55 can rotate the steering motor 36 at the target steering angle speed θd*. Or, in other words, the steering motor 36 can generate the required output power Opra. That is, in this case, the vehicle 10 can travel along the target vehicle steering path Prp under automatic drive support control.

[0129] On the other hand, if, for example, the required voltage Vr of the steering motor 36 is higher than 8 V while the engine 11 is being restarted (that is, in the state in which the starter motor 12 is turning), the steering control ECU 55 cannot supply a voltage of at least the required voltage Vr to the steering motor 36. Or, put another way: if the required torque Trq is above the straight dashed line Lc in Fig. If position 3 is omitted while motor 11 is restarting, the steering control ECU 55 cannot rotate the steering motor 36 at the target steering angular velocity θd*. For example, if the voltage of battery 14 is the restart time minimum voltage Vminrs (8 V) and the required voltage Vr of the steering motor 36 is higher than 8 V, the steering control ECU 55 cannot rotate the steering motor 36 at the target steering angular velocity θd*.

[0130] In this case, the steering control ECU 55 causes the battery 14 to supply the maximum suitable voltage to the steering motor 36. However, the maximum suitable voltage is lower than the required voltage Vr. Therefore, the steering motor 36 cannot turn the steering wheel 32 at the target steering angular velocity θd* while generating the required torque Trq. That is, in this case, the vehicle 10 does not travel along the target vehicle steering path Prp under the automatic drive assist control.

[0131] When the vehicle 10 is in automatic drive assist mode, the driver may pay less attention to the steering wheel 32 than if the vehicle 10 were not in automatic drive assist mode. If the vehicle 10 does not travel along the intended steering path Prp while the driver pays less attention to the steering wheel 32, the driver may experience significant discomfort.

[0132] Therefore, in the present embodiment, when the vehicle 10 is in automatic drive support mode, the required voltage monitoring ECU 56 determines, based on the required voltage Vr of the steering motor 36 and the state of the motor 11, whether the engine control ECU 51 should be allowed to execute the StSt control.

[0133] That is, the required voltage monitoring ECU 56 compares the minimum stop-time voltage Vmins or the minimum restart-time voltage Vminrs, each of which is the minimum voltage of the battery 14 determined by the state of the motor 11, with the required voltage Vr. Or, put another way, the required voltage monitoring ECU 56 essentially compares the maximum values ​​(straight dashed lines Lb, Lc) of the torque that the steering motor 36 can generate when each minimum voltage is applied to the steering motor 36 with the required torque Trq, which is determined based on the curve diagram of Fig. 4 is calculated.

[0134] For example, the required voltage monitoring ECU 56 sets a stop-permit flag to "1" while the motor 11 is in normal operation if the required voltage Vr reaches a maximum of 12 V at the current time. Or, put another way: if the required torque Trq is on or below the straight dashed line Lb in Fig. If position 3 is found, the Required Voltage Monitoring ECU 56 sets the Stop Permission Flag to “1”.

[0135] On the other hand, the required voltage monitoring ECU 56 sets the stop-permit flag to "0" while the motor 11 is in normal operating condition if the required voltage Vr at the current time exceeds 12 V. Or, put another way: if the required torque Trq is above the straight dashed line Lb in Fig. When position 3 is reached, the Required Voltage Monitoring ECU 56 sets the Stop Permission Flag to "0". The initial value of the Stop Permission Flag is "0".

[0136] Then, if the stop condition is met at the current time, the engine control ECU 51 determines, based on the value of the stop permission flag set by the required voltage monitoring ECU 56 at the current time, whether engine 11 should be stopped. That is, if the stop condition is met at the current time and the stop permission flag is "1" at the current time, the engine control ECU 51 stops engine 11 under the control unit. Furthermore, if the stop permission flag is "0" at the current time, the engine control ECU 51 does not stop engine 11 under the control unit. In this case, the engine control ECU 51 does not stop engine 11 under the control unit, even if the stop condition is met at the current time.

[0137] For example, the stopping condition is at time t1 in Fig. 3. However, the required voltage Vr at this point is greater than the minimum stop-time voltage Vmins (12 V) of battery 14. Or in other words: in Fig. 3. The required torque Trq is positioned above the straight, broken line Lb. Therefore, the stop permission flag is "0" at this time. Therefore, the engine control ECU 51 does not stop engine 11 at time t1.

[0138] On the other hand, the stopping condition is at time t2 in Fig. 3. Furthermore, the required voltage Vr at this time is not greater than the minimum stop-time voltage Vmins (12 V) of battery 14. Or in other words: in Fig. 3. The required torque Trq is positioned below the straight, broken line Lb. Therefore, the stop-permit flag is "1" at this time. Therefore, the engine control ECU 51 stops the engine 11 at time t2.

[0139] However, even when the automatic drive assist mode is selected by actuating the automatic drive assist mode selector switch 60, the motor control ECU 51 can immediately stop the motor 11 if the stop condition is met, regardless of the value of the stop permission flag. This occurs when a previously defined exception condition is met.

[0140] For example, if the driver operates the turn signal lever 21 to transmit an operating signal from the turn signal lever 21 from the vehicle control ECU 52 to the engine control ECU 51, the engine control ECU 51 determines that the exception condition is met.

[0141] For example, if vehicle number 10 is in the Fig. When the vehicle is positioned as shown in section 2, the driver intentionally turns the steering wheel 32 clockwise while the turn signal 22R is flashing. The vehicle 10 then crosses lane 72 and enters lane 81 of road 80.

[0142] In this way, when the driver voluntarily operates the steering wheel 32, the steering control ECU 55 calculates the target steering assistance torque based on the steering torque Tr detected by the steering torque sensor 35 and the vehicle speed V. Furthermore, the steering control ECU 55 controls the steering motor 36 so that it generates the target steering assistance torque.

[0143] In this case, the required voltage Vr of the steering motor 36, which corresponds to the target power steering torque, can be greater than the minimum stop-time voltage Vmins of the battery 14. However, if the driver operates the steering wheel 32 voluntarily, even if the steering motor 36 cannot generate the desired output power, it is unlikely that the driver will experience significant discomfort. Therefore, if the stop condition is met in this case, the engine control ECU 51 immediately stops the engine 11, regardless of the value of the stop-permit flag.

[0144] If the required voltage Vr reaches a maximum of 8 V at the time when the required time to start Trs has elapsed from the current time, while the motor 11 is in the operating stop state, the required voltage monitoring ECU 56 sets a restart permit flag to "1" at the current time. Or, in other words: if the required torque Trq is on or below the straight dashed line Lc at the time when the required time to start Trs has elapsed, Fig. When position 3 is reached, the Required Voltage Monitoring ECU 56 sets the Restart Permission Flag to "1".

[0145] However, if the required voltage Vr becomes greater than 8 V at the time when the required time to start Trs has elapsed from the current time, while the motor 11 is in the operating stop state, the required voltage monitoring ECU 56 sets the restart permission flag to "0" at the current time. Or in other words: if the required torque Trq is above the straight dashed line Lc at the time when the required time to start Trs has elapsed, Fig. When position 3, the Required Voltage Monitoring ECU 56 sets the Restart Permission Flag to "0". The initial value of the Restart Permission Flag is "0".

[0146] When the restart condition is met, the engine control ECU 51 determines, based on the value of the restart permission flag set by the required voltage monitoring ECU 56, whether the engine 11 should be restarted. That is, if the restart condition is met at the current time and the restart permission flag is "1" at the current time, the engine control ECU 51 restarts the engine 11 under the starter control. Or, put another way, the engine control ECU 51 supplies the electricity from battery 14 to the starter motor 12. Conversely, if the restart condition is met at the current time and the restart permission flag is "0" at the current time, the engine control ECU 51 does not restart the engine 11 under the starter control. Or to put it another way: the engine control ECU 51 does not feed the electricity from the battery 14 into the starter motor 12.

[0147] For example, the restart condition is in the period at or after time t2 and before time t3 in Fig. 3 is not met, and the restart condition is met at time t3.

[0148] Furthermore, the required voltage Vr at time t4, which occurs when the time required to start Trs has elapsed from time t3, is not greater than the minimum restart time voltage Vminrs (8 V) of battery 14. Or, put another way: in Fig. The required torque Trq is positioned below the straight, dashed line Lc. Therefore, at time t3, the required voltage monitoring ECU 56 sets the restart allow flag to "1". Consequently, at time t3, the engine control ECU 51 restarts the engine 11. That is, at time t3, the engine control ECU 51 supplies the electricity from battery 14 to the starter motor 12, so that a first power stroke is performed in the engine 11. In this case, time t4 can be referred to as the complete power stroke time, and the required voltage Vr at time t4 can be referred to as the required power stroke time voltage.

[0149] A complete power cycle is executed (completed) before time t4, which is the complete power cycle completion time, arrives in motor 11, in which a first power cycle was executed (completed) immediately after time t3. That is, the starter motor 12 is in a stop state at time t4.

[0150] The required voltage Vr at time t5, which comes after time t4, is greater than the restart time minimum voltage Vminrs (8 V) of battery 14. Or in other words: in Fig. 3. The required torque Trq is positioned above the straight dashed line Lc. However, since the starter motor 12 is in the stop state at time t5, the minimum voltage of the battery 14, which is determined by the state of the motor 11, is the normal operating time minimum voltage Vmind (14 V) at time t5. Therefore, in this case, the required torque Trq is below the straight dashed line La. Fig. 3 is positioned. Accordingly, at time t5, a voltage of at least the required voltage Vr is fed into the steering motor 36.

[0151] If the control device 50 is designed to feed the electricity from the battery 14 into the starter motor 12 at time t4, then, if the restart condition is met at time t4 and the restart permission flag is switched from “0” to “1” at time t4, a first working stroke will be performed in the motor 11 immediately after time t4.

[0152] If the control device 50 is configured in this way, a complete working cycle is executed in the motor 11 at time t6. That is, in the period between time t4 and time t6, the minimum voltage of the battery 14 is the restart time minimum voltage Vminrs (8 V). Or, put another way: in the period between time t5 and time t6, the required voltage Vr is higher than the restart time minimum voltage Vminrs. That is, in this period, the required torque Trq is above the straight dashed line Lc. Fig. 3 positioned.

[0153] Therefore, in this case, no voltage of at least the required voltage Vr is supplied to the steering motor 36 during the period between time t5 and time t6. This means that during this period, the vehicle 10 does not travel along the intended vehicle steering path Prp under the automatic drive support control.

[0154] However, even when the automatic drive assist mode is selected by actuating the automatic drive assist mode selector switch 60, the engine control ECU 51 can immediately restart the engine 11 if the restart condition is met, regardless of the value of the restart allow flag. This occurs when a previously defined emergency condition is met.

[0155] For example, when the collision avoidance control is executed, the engine control ECU 51 determines that the emergency condition has been met.

[0156] For example, if another vehicle (not shown) positioned in front of vehicle 10 and traveling in lane 72 mistakenly enters lane 71 while vehicle 10 is performing inertial travel in lane 71 and engine 11 is stopped, the vehicle control ECU 52 can perform automatic steering control.

[0157] In this case, the vehicle control ECU 52 can determine, based on the positional relationship between vehicle 10 and another vehicle described above, and the relative speed between them, that the probability of vehicle 10 avoiding a collision with another vehicle described above under automatic steering control is higher if engine 11 is started immediately than if engine 11 is kept in the operating stop state. In this case, the engine control ECU 51 restarts engine 11 immediately, regardless of the value of the restart permission flag.

[0158] Next, a specific processing operation performed by the control device 50 will be described with reference to the flowcharts of the Fig. 5, Fig. 6, Fig. 7, Fig. 8 to Fig. 9 described.

[0159] When the ignition switch of the vehicle 10 is switched from OFF to ON by operating an ignition key, the steering control ECU 55 executes the steps shown in the flowchart of Fig. The routine shown in Figure 5 is repeated each time the calculation interval time Tc (for example, 1 second) has elapsed. In the present embodiment, the calculation interval time Tc is set to 1 / 5 of the time required to start Trs. For example, the calculation interval time Tc can be set to 1 second, and the time required to start Trs can be set to 5 seconds.

[0160] First, in step 501, the steering control ECU 55 determines whether the automatic drive assist mode is selected by the automatic drive assist mode selector switch 60 or not.

[0161] If "Yes" is determined in step 501, the steering control ECU 55 proceeds to step 502. If the automatic drive assist mode is selected, the control device 50 continuously supplies electricity from the battery 14 to the steering motor 36. That is, the battery 14 supplies the maximum suitable voltage to the steering motor 36.

[0162] As it progresses to step 502, the steering control ECU 55 calculates the vehicle's desired steering path Prp of the front section Fp of the road 70 based on image display data which includes the white line 70A and the white line 70B and is received from the camera control ECU 54.

[0163] The steering control ECU 55, which has completed the processing of step 502, proceeds to step 503 to calculate the curvature ρ of the front section Fp based on the vehicle's desired steering path Prp.

[0164] The steering control ECU 55, which has completed processing step 503, proceeds to step 504 to calculate the target steering angle θ* and the target steering angle velocity θd*, both of which correspond to the front section Fp based on the curvature ρ of the front section Fp. Or, put another way, the steering control ECU 55 calculates the target steering angle θ* as the time required to start Trs later and the target steering angle velocity θd* as the time required to start Trs later.

[0165] The steering control ECU 55, having completed processing step 504, proceeds to step 505 to calculate the limiting speed V*, corresponding to the front section Fp, based on the target steering angle θ* and the limiting lateral acceleration. In other words, the steering control ECU 55 calculates the limiting speed V* and the time required to start Trs later.

[0166] The steering control ECU 55, having completed step 505, proceeds to step 506 to calculate the required output torque Trq of the steering motor 36, corresponding to the front section Fp, based on the target steering angle θ* and the limiting speed V*. In other words, the steering control ECU 55 calculates the required torque Trq and the time required to start Trs later.

[0167] Furthermore, the steering control ECU 55 calculates the required output power Opra of the steering motor 36, which corresponds to the front section Fp, based on the required torque Trq and the target steering angle speed θd*. Or, put another way: the steering control ECU 55 calculates the required output power Opra and the time required to start Trs later.

[0168] The steering control ECU 55, having completed processing step 506, proceeds to step 507 to calculate the required voltage Vr of the steering motor 36, corresponding to the front section Fp, based on the required output power Opra. In other words, the steering control ECU 55 calculates the required voltage Vr and the time needed to start Trs later.

[0169] The steering control ECU 55, which has completed the processing of step 507, proceeds to step 508 to record the required voltage Vr, which corresponds to the front section Fp, in its memory device.

[0170] The steering control ECU 55, which has finished processing step 508, temporarily stops processing this routine.

[0171] If the steering control ECU 55 determines No in step 501, the steering control ECU 55 temporarily terminates the processing of this routine.

[0172] When the vehicle's ignition switch 10 is switched from OFF to ON by turning the ignition key, the Required Voltage Monitoring ECU 56 performs the steps shown in the flowchart of Fig. The routine shown in Figure 6 is repeated each time the calculation interval time Tc has elapsed.

[0173] First, in step 701, the Required Voltage Monitoring ECU 56 determines whether the automatic drive assist mode is selected by the Automatic Drive Assist Mode Selector Switch 60 or not.

[0174] If "yes" is determined in step 701, the steering control ECU 55 proceeds to step 702.

[0175] In step 702, the Required Voltage Monitoring ECU 56 determines whether or not the motor 11 is in normal operating condition.

[0176] The Required Voltage Monitoring ECU 56, which determined Yes in step 702, proceeds to step 703 to determine whether the required voltage Vr at the current time is at most as large as the Stop Time Minimum Voltage Vmins (12 V) or not.

[0177] The Required Voltage Monitoring ECU 56, which determined Yes in step 703, proceeds to step 704 to set the Stop Permission flag to “1”.

[0178] On the other hand, the Required Voltage Monitoring ECU 56, which determined No in step 703, proceeds to step 705 to set the Stop Permission flag to “0”.

[0179] After the processing of step 704 or step 705 is completed, the Required Voltage Monitoring ECU 56 temporarily stops processing this routine.

[0180] If No is determined in step 701 or 702, the Required Voltage Monitoring ECU 56 temporarily stops processing this routine.

[0181] When the vehicle's ignition switch 10 is switched from OFF to ON by turning the ignition key, the Required Voltage Monitoring ECU 56 performs the steps shown in the flowchart of Fig. The routine shown in Figure 7 is repeated each time the calculation interval time Tc has elapsed.

[0182] First, in step 801, the Required Voltage Monitoring ECU 56 determines whether the automatic drive assist mode is selected by the Automatic Drive Assist Mode Selector Switch 60 or not.

[0183] If "yes" is determined in step 801, the steering control ECU 55 proceeds to step 802.

[0184] In step 802, the Required Voltage Monitoring ECU 56 determines whether the motor 11 is in the operating stop state or not.

[0185] The Required Voltage Monitoring ECU 56, which determined Yes in step 802, proceeds to step 803 to determine whether the required voltage Vr is at most as large as the restart time minimum voltage Vminrs (8 V) or not.

[0186] The Required Voltage Monitoring ECU 56, which determined Yes in step 803, proceeds to step 804 to set the Restart Permission Flag to “1”.

[0187] On the other hand, the Required Voltage Monitoring ECU 56, which determined No in step 803, proceeds to step 805 to set the Restart Permission Flag to “0”.

[0188] After the processing of step 804 or step 805 is completed, the Required Voltage Monitoring ECU 56 temporarily stops processing this routine.

[0189] If No is determined in step 801 or 802, the Required Voltage Monitoring ECU 56 temporarily stops processing this routine.

[0190] When the vehicle's ignition switch 10 is switched from OFF to ON by turning the ignition key, the engine control ECU 51 executes the process shown in the flowchart of Fig. The routine shown in step 8 is repeated each time the calculation interval time Tc has elapsed.

[0191] First, in step 901, the engine control ECU 51 determines whether the automatic drive assist mode is selected by the automatic drive assist mode selector switch 60 or not.

[0192] If "yes" is determined in step 901, the engine control ECU 51 proceeds to step 902.

[0193] In step 902, the engine control ECU 51 determines whether the engine 11 is in normal operating condition or not.

[0194] The engine control ECU 51, which determined yes in step 902, proceeds to step 903 to determine whether a preliminary stop condition is met or not.

[0195] The preliminary stop condition is met if, for example, the vehicle speed V of vehicle 10 is at most as large as the previously set speed (for example, 10 km / h or less) and the actuation amount AP of the accelerator pedal A / P is zero.

[0196] The engine control ECU 51, which determined yes in step 903, proceeds to step 904 to add “1” to the value of a preliminary stop condition fulfillment counter.

[0197] On the other hand, the engine control ECU 51, which determined No in step 903, proceeds to step 909 to set the value of the preliminary stop condition fulfillment counter to “0”.

[0198] The engine control ECU 51, which has completed processing step 904, proceeds to step 905 to determine whether the value of the preliminary stop condition fulfillment counter is at least as large as a previously set initial threshold count Thc1 or not.

[0199] The first threshold count Thc1 is stored in the memory device of the engine control ECU 51.

[0200] The first threshold count Thc1 can be, for example, "3".

[0201] If the engine control ECU 51 determines "yes" in step 905, then the stop condition is met.

[0202] If the stop condition is met, the engine control ECU 51 proceeds to step 906 to determine whether the exception condition is met or not.

[0203] If No is determined in step 906, the engine control ECU 51 proceeds to step 907 to determine whether the stop permission flag is “1” or not.

[0204] The engine control ECU 51, which determined "yes" in step 907, proceeds to step 908 to stop engine 11. That is, the engine control ECU 51 stops engine 11 under the control of the StSt.

[0205] If, however, the engine control ECU 51 determines "Yes" in step 906, then the engine control ECU 51 proceeds to step 908 to stop engine 11. That is, the engine control ECU 51 stops engine 11 under the StSt control regardless of the value of the stop permission flag.

[0206] The engine control ECU 51, which has finished processing step 908 or step 909, temporarily stops processing this routine.

[0207] When the vehicle's ignition switch 10 is switched from OFF to ON by turning the ignition key, the engine control ECU 51 executes the process shown in the flowchart of Fig. The routine shown in step 9 is repeated each time the calculation interval time Tc has elapsed.

[0208] First, in step 1001, the engine control ECU 51 determines whether the automatic drive assist mode is selected by the automatic drive assist mode selector switch 60 or not.

[0209] If "yes" is determined in step 1001, the engine control ECU 51 proceeds to step 1002.

[0210] In step 1002, the engine control ECU 51 determines whether the engine 11 is in the operating stop state or not.

[0211] The engine control ECU 51, which determined yes in step 1002, proceeds to step 1003 to determine whether a preliminary restart condition is met or not.

[0212] The preliminary restart condition is met if, for example, the actuation amount AP of the accelerator pedal A / P is greater than zero.

[0213] The engine control ECU 51, which determined yes in step 1003, proceeds to step 1004 to add “1” to the value of a preliminary restart condition fulfillment counter.

[0214] On the other hand, the engine control ECU 51, which determined no in step 1003, proceeds to step 1009 to set the value of the preliminary restart condition fulfillment counter to “0”.

[0215] The engine control ECU 51, which has completed processing step 1004, proceeds to step 1005 to determine whether the value of the preliminary restart condition fulfillment counter is at least as large as a previously set second threshold count Thc2 or not.

[0216] The second threshold count Thc2 is stored in the memory device of the engine control ECU 51.

[0217] The second threshold count Thc2 can be, for example, "3".

[0218] If the engine control ECU 51 determines "yes" in step 1005, then the restart condition is met.

[0219] If the restart condition is met, the engine control ECU 51 proceeds to step 1006 to determine whether the emergency condition is met or not.

[0220] If the engine control ECU 51 determines No in step 1006, the engine control ECU 51 proceeds to step 1007 to determine whether the restart permission flag is “1” or not.

[0221] The engine control ECU 51, which determined "yes" in step 1007, proceeds to step 1008 to restart engine 11. This means that the engine control ECU 51 operates engine 11 under the control of the starter motor control unit (StSt) in such a way that a first power stroke is executed.

[0222] If, however, "Yes" is determined in step 1006, the engine control ECU 51 proceeds to step 1008 to restart engine 11. This means that, regardless of the value of the restart permission flag, the engine control ECU 51 restarts engine 11 under the control of the StSt (stationary control unit).

[0223] The engine control ECU 51, which has finished processing step 1008 or step 1009, temporarily stops processing this routine.

[0224] It should be noted that the present invention is not limited to the embodiment described above and that various modified embodiments may be used within the scope of the present invention.

[0225] For example, the present invention can be implemented in the manner of a Fig. 10 shown first modified embodiment.

[0226] In the first modified embodiment, when a previously defined electrical suppression condition is met, the steering control ECU 55 calculates the required voltage Vr corresponding to the front section Fp using a different method than that of the embodiment described above. In other words, the required voltage Vr for the time required to start Trs later is calculated by the steering control ECU 55 using a different method than that of the embodiment described above.

[0227] For example, if an (not shown) ECO mode selector switch located in vehicle 10 is switched from an OFF position to an ON position by an occupant of vehicle 10, then the electricity suppression condition is met.

[0228] In the first modified embodiment, when the ignition switch of the vehicle 10 is switched from OFF to ON by actuating the ignition key, the steering control ECU 55 executes the steps shown in the flowchart of Fig. The routine shown in step 10 is repeated each time the calculation interval time Tc has elapsed.

[0229] The processing of each of steps 1101 to 1106 of this flowchart is the same as that of each of steps 501 to 506 of Fig. 5. Furthermore, the processing of each of steps 1109 and 1110 is the same as that of each of steps 507 and 508 in Fig. 5.

[0230] The steering control ECU 55, which has completed processing step 1106, proceeds to step 1107 to determine whether the electricity suppression condition is met or not.

[0231] The steering control ECU 55, which determined "No" in step 1107, proceeds to step 1109 and then to step 1110. That is, in this case, the steering control ECU 55 performs the same processing as steps 507 and 508 in the flowchart of Fig. 5.

[0232] On the other hand, the steering control ECU 55, which determined "yes" in step 1107, proceeds to step 1108 to correct the value of the required output power Opra, which corresponds to the front section Fp calculated in step 1106. More precisely, the steering control ECU 55 multiplies the required output power Opra calculated in step 1106 by a previously defined coefficient.

[0233] This coefficient is less than 1 and greater than 0. For example, 0.7 can be used as this coefficient.

[0234] The steering control ECU 55, which has completed the processing of step 1108, proceeds to step 1109 to calculate the required voltage Vr, which corresponds to the corrected required output power Opra.

[0235] This required voltage Vr is less than the required voltage Vr when the steering control ECU 55 advances to step 1109 after No was determined in step 1107.

[0236] Therefore, in this case, if the required voltage Vr recorded in step 1110 is fed into the steering motor 36 at the time when the time required to start Trs has elapsed, the steering motor 36 will be operated with less electricity than if the steering control ECU 55 determines No in step 1107.

[0237] However, in this case, if vehicle 10 passes the front section Fp at the time when the time required to start Trs has elapsed, the actual vehicle steering path Pf of vehicle 10 deviates slightly from the vehicle intended steering path Prp, as shown in Fig. 2 shown.

[0238] The vehicle 10 can be configured such that at least one of the minimum normal operating time voltage Vmind, the minimum stop time voltage Vmins, and the minimum restart time voltage Vminrs has a value that differs from the corresponding minimum voltages in the embodiment and the modified embodiment. For example, the vehicle 10 can be configured such that the minimum restart time voltage Vminrs is 9 V.

[0239] In the embodiment and the modified embodiment, the steering motor 36 can be a three-phase brushless motor.

Claims

[1] Vehicle control device comprising: an internal combustion engine (11) installed in a vehicle (10), a power generating device (13) for generating electricity using the power of the internal combustion engine (11), a battery (14) for storing the electricity generated by the power generating device (13), an electric starter motor (12) designed to rotate in order to start the internal combustion engine (11) when it is supplied with electricity from the battery (14), an electric power steering device (25) comprising an electric steering motor (36) configured to rotate in order to change the steering angles of steered wheels (15FL, 15FR) of the vehicle (10) when it is supplied with electricity from the battery (14); and a control unit (50, 55) designed such that it a voltage is supplied to the steering motor (36) using the electricity from the battery (14) to rotate the steering motor (36); stops the operation of the internal combustion engine (11) which is in an operating state when a previously defined stop condition is met; the starter motor (12) turns to restart the internal combustion engine (11), which is in an operating stop state, when a previously defined restart condition is met; and a required voltage (Vr) is calculated, which is the voltage needed to turn the steering motor to produce a previously determined output power; wherein the control unit (50, 55) is further designed to to be able to stop the internal combustion engine (11) when the required voltage (Vr) is at most as large as a first voltage value (Vmins) while the stopping condition is met; to be unable to stop the internal combustion engine (11) if the required voltage (Vr) is greater than the first voltage value (Vmins) while the stop condition is met; to be able to restart the internal combustion engine (11) when the required voltage (Vr) is at most as large as a second voltage value (Vminrs) that is smaller than the first voltage value (Vmins) while the restart condition is met; and to be unable to restart the internal combustion engine (11) if the required voltage (Vr) is greater than the second voltage value (Vminrs) while the restart condition is met. [2] Vehicle control device according to claim 1, wherein the control unit (50, 55) is configured to: to calculate a vehicle target steering path (Prp), which is a vehicle steering path of the vehicle (10) when a previously defined period of time (Trs) has elapsed; and to calculate the required voltage (Vr) when the previously specified period (Trs) has elapsed, so that the vehicle (10) travels along the vehicle's intended steering path (Prp). [3] Vehicle control device according to claim 1 or 2, wherein the control unit (50, 55) is configured to: to calculate a required power-stroke completion time voltage, which is the required voltage at a complete power-stroke completion time, wherein the complete power-stroke completion time is a time at which a complete power stroke is presumably completed in the internal combustion engine (11) when the starter motor (12) is started at a previously predetermined time, and the complete power-stroke completion time is a time at which a previously predetermined required time for starting has elapsed since the previously predetermined time; and to start the starter motor (12) at the previously specified time, where the required working cycle completion time voltage is at most as large as the second voltage value. [4] Vehicle control device according to one of claims 1 to 3, wherein the control unit (50, 55) is configured to: to calculate the required voltage (Vr) when a previously defined electricity suppression condition is met, such that the required voltage (Vr) when the previously defined electricity suppression condition is met is less than the required voltage (Vr) that is calculated when the previously defined electricity suppression condition is not met.

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