JP5035059B2 - Vehicle control device - Google Patents

Description

  The present invention relates to a vehicle control device, and more particularly, to a vehicle control device equipped with a so-called eco-run control system that temporarily stops an engine when a predetermined condition is satisfied.

  In recent vehicles, almost all vehicles are equipped with a power steering device. The power steering device includes a hydraulic assist type and an electric assist type. The electric assist type cannot generate as much assist force as the hydraulic assist type, but it does not require hydraulic piping and has a simple structure. Therefore, the electric assist type has become popular mainly in small vehicles, and has recently been adopted in large vehicles. Yes.

  Various configurations of electric power steering devices have been proposed. For example, an assist torque is generated during steering by a motor and a speed reducer attached to a column shaft connected to a steering wheel to reduce steering operation force. There is something. This electric power steering device is controlled by an electric power steering control device. The electric power steering controller calculates the assist current based on the torque signal and the vehicle speed signal from the torque sensor built in the steering column, and generates the assist torque by controlling the current supplied to the power steering motor. (For example, refer to Patent Document 1).

Such an electric power steering control device normally has a fail-safe function in case an abnormality such as a disconnection or a semiconductor element failure occurs. For example, the electric power steering control device monitors the voltage at a predetermined position in the internal circuit, and when this voltage falls below a predetermined threshold, the power supply to the power steering motor is stopped and the manual steering state is stopped. Or a warning lamp is lit to notify the driver of the abnormality.
JP-A-5-77755

  By the way, in recent years, in order to prevent global warming and save energy, an increasing number of vehicles are equipped with an eco-run control system that automatically stops the engine when the vehicle is stopped and restarts it when the vehicle is restarted. This eco-run control system is also called an idling stop system.

  In a vehicle equipped with such an eco-run control system, a large amount of electric power is supplied to the starter motor when the engine is restarted by the eco-run control, so that the battery voltage may decrease. In this case, since the supply voltage to the electric power steering control device is reduced, the monitored voltage becomes lower than the threshold voltage even though no abnormality has occurred, and the occurrence of the abnormality may be erroneously determined. There is. If an erroneous determination of abnormality occurs, the electric power steering device cannot be started during the eco-run control, or a warning lamp may be lit, which may cause discomfort to the driver.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a vehicle control device capable of preventing erroneous determination of abnormality in an electronic power steering control device.

  In order to solve the above problems, a vehicle control apparatus according to an aspect of the present invention drives an motor and an eco-run control unit that performs eco-run control for temporarily stopping the engine when a predetermined stop condition is satisfied. Thus, the electric power steering control unit for applying steering assist force to the steering system and the voltage at a predetermined position in the internal circuit of the electric power steering control unit are monitored, and when the voltage is equal to or lower than a predetermined threshold voltage, An abnormality determination unit that determines that an abnormality has occurred in the power steering control unit. When the eco-run control unit detects that the voltage supplied to the electric power steering control unit decreases while the eco-run control unit is executing the eco-run control, the abnormality determination unit sets a threshold voltage for determining an abnormality to a predetermined value during normal operation. The first threshold voltage is changed to a predetermined second threshold voltage in consideration of a drop in supply voltage.

  According to this aspect, for example, even when an auxiliary machine that consumes a large amount of electric power during eco-run control is activated and the voltage supplied to the electric power steering control unit is reduced, it is possible to prevent erroneous determination of abnormality. As a result, it is possible to prevent the driver from feeling uncomfortable because the electric power steering device cannot be started during the eco-run control or the warning lamp is turned on.

  When the eco-run control unit detects that the eco-run control unit is restarting the engine while the eco-run control unit is executing the eco-run control, the abnormality determination unit sets a threshold voltage for determining an abnormality to a predetermined value during normal operation. You may change from 1 threshold voltage to the predetermined 2nd threshold voltage which considered the fall of the supply voltage.

  When the engine is restarted by eco-run control, the voltage supplied to the electric power steering device is reduced due to the consumption of large electric power. By changing to, erroneous determination of abnormality can be prevented.

  ADVANTAGE OF THE INVENTION According to this invention, the vehicle control apparatus which can prevent the erroneous determination of abnormality in an electronic power steering control apparatus can be provided.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a vehicle control apparatus 100 according to an embodiment of the present invention. The vehicle control device 100 can execute so-called eco-run control that temporarily stops the engine when a predetermined condition is satisfied. That is, the vehicle control apparatus 100 stops the engine when a predetermined stop condition is satisfied, and restarts the engine when a predetermined restart condition is satisfied such as when an accelerator pedal is depressed.

  1 includes an eco-run control device (hereinafter referred to as eco-run ECU) 10, an engine control device (hereinafter referred to as engine ECU) 12, an ABS control device (hereinafter referred to as ABS ECU) 16, and An electric power steering control device (hereinafter referred to as EPSECU) 22 is included. The eco-run ECU 10, the engine ECU 12, the ABS ECU 16, and the EPS ECU 22 are each configured as a microprocessor including a CPU. In addition to the CPU, a ROM that stores various programs, a RAM that temporarily stores data, an input / output port, and a communication port Etc.

  The eco-run ECU 10 is connected to the engine ECU 12, the ABS ECU 16, and the EPS ECU 22 so that various control signals can be communicated with each other. Further, in the eco-run ECU 10, the engine ECU 12, the ABS ECU 16, and the EPS ECU 22 are each supplied with electric power from a battery 24 mounted on the vehicle.

  The engine ECU 12 controls the engine 14 based on input signals indicating, for example, accelerator on / off, accelerator opening, shift position, engine speed, and the like. These signals are obtained by various sensors or the like (not shown) connected to the engine ECU 12. For example, the accelerator on / off and the accelerator opening are controlled by an accelerator switch, and the shift position is detected by a shift position sensor. The number is acquired by the NE sensor and transmitted to the engine ECU 12.

  The ABS ECU 16 is a control device for executing ABS control for preventing the tire from locking when braking on a slippery road surface, for example. The ABS ECU 16 appropriately executes ABS control based on, for example, the wheel speed monitored by a wheel speed sensor (not shown).

  The eco-run ECU 10 outputs an engine stop command signal and an engine restart command signal for eco-run control to the engine ECU 12 based on various signals indicating the engine operating state from the engine ECU 12 and signals indicating the wheel speed from the ABS ECU 16. . Based on the engine stop command signal and the engine restart command signal from the eco-run ECU 10, the engine ECU 12 outputs control signals such as fuel injection, intake air, and ignition control to the engine 14 to control the stop and restart of the engine 14. . When an engine restart command signal is input from the eco-run ECU 10, the engine ECU 12 drives a starter motor 26 provided in the engine 14 to restart the engine 14. The eco-run ECU 10 may be connected to a master cylinder pressure sensor (not shown) for measuring the master cylinder pressure, and the eco-run ECU 10 may be configured to monitor the master cylinder pressure.

  In the eco-run ECU 10, for example, the vehicle speed is zero or below a predetermined value, the shift position is a drive position, the master cylinder pressure is above a predetermined value, and the like are set in advance as engine stop conditions. The eco-run ECU 10 outputs an engine stop command signal to the engine ECU 12 when all of these conditions are satisfied, for example. Alternatively, an engine stop command signal may be output to engine ECU 12 when any of these conditions is satisfied. When the engine 14 is stopped by the eco-run control, the eco-run ECU 10 turns on and holds a flag indicating that the engine 14 has been stopped.

  When the engine 14 is automatically stopped and restarted when a predetermined restart condition is satisfied, the eco-run ECU 10 performs, for example, the following process. First, the eco-run ECU 10 determines whether or not the engine 14 is in a stop state by eco-run control based on the above flag. When the engine 14 is not stopped by the eco-run control, the eco-run ECU 10 does not perform a restart process so that the engine 14 is not automatically started. When the engine 14 is in the stop state by the eco-run control, the eco-run ECU 10 determines whether or not the engine restart condition is satisfied. The engine restart conditions include, for example, that the brake pedal depression amount is below a predetermined amount, continues for a predetermined time, the accelerator pedal depression amount has reached a predetermined amount, or the vehicle speed has reached a predetermined value or more. Etc. are preset. When all or any of these engine restart conditions are satisfied, the eco-run ECU 10 outputs an engine restart command signal to the engine ECU 12. When the engine restart condition is not satisfied, the engine stop state is continued.

  The EPS ECU 22 calculates an assist current based on a torque signal and a vehicle speed signal from a torque sensor (not shown) built in the steering column portion of the vehicle, and supplies a current supplied to the power steering motor 28 of the electric power steering device. By controlling, an assist torque is generated. Thereby, a steering assist force is applied to the steering system, and the driver can perform steering with a small force.

  By the way, EPSECU22 of this Embodiment has a fail safe function in preparation for when abnormality, such as a disconnection and a semiconductor element failure, generate | occur | produces. More specifically, the EPS ECU 22 monitors the voltage at a predetermined position in the internal circuit, and when this voltage falls below a predetermined threshold, the supply of power to the power steering motor is stopped and manual steering is performed. To make a condition or to turn on the warning lamp to inform the driver of the abnormality. is doing.

  FIG. 2 is a diagram illustrating a part of the internal circuit of the EPSECU 22. FIG. 2 shows a peripheral circuit of the power input unit that receives power from the battery 24. As shown in FIG. 2, the positive terminal 24a of the battery 24 is connected to the power input positive terminal 22a of the EPS ECU 22 via the wire harness 30, and the negative terminal 24b of the battery 24 is connected to the power input negative terminal 22b of the EPS ECU 22. They are connected via a wire harness 31. The power input minus terminal 22 b is grounded inside the battery 24.

  In the EPSECU 22, the power input plus terminal 22 a is connected to the booster circuit 40. The booster circuit 40 includes a first capacitor 42, a second capacitor 50, an inductor 44, a first MOSFET 46, a second MOSFET 48, and a diode 52.

  One end of the first capacitor 42 is connected to the power input plus terminal 22a, and the other end of the first capacitor 42 is grounded. The power input plus terminal 22a is also connected to one end of the inductor 44. The other end of the inductor 44 is connected to the drain of the first MOSFET 46, and the source of the first MOSFET 46 is grounded. The other end of the inductor 44 is connected to the cathode of the diode 52, and the anode of the diode 52 is connected to a constant voltage source of 5V. The other end of the inductor 44 is connected to the source of the second MOSFET 48, and the drain of the second MOSFET 48 is connected to the inverter circuit at the subsequent stage. The drain of the second MOSFET 48 is connected to one end of the second capacitor 50, and the other end of the second capacitor 50 is grounded. For example, when a voltage of 12V is input to the power supply input plus terminal 22a, the booster circuit 40 configured as described above boosts the voltage to, for example, about 33V and supplies it to the subsequent inverter circuit.

  The EPS ECU 22 includes an abnormality determination unit 32 that determines whether an abnormality has occurred in itself. The abnormality determination unit 32 monitors the voltage at point A to which the inductor 44, the drain of the first MOSFET 46, the cathode of the diode 52, and the source of the second MOSFET 48 in the booster circuit 40 are connected. And when the voltage of A point is below a predetermined threshold voltage, it determines with abnormality having occurred in EPSECU22. The abnormality determination unit 32 includes a threshold voltage setting unit that sets a predetermined threshold voltage, and a voltage comparison unit that compares the threshold voltage with the voltage at point A. If the abnormality determination unit 32 determines that an abnormality has occurred, the EPS ECU 22 may not be able to stably drive the electric power steering control device, and therefore stops supplying power to the power steering motor 28.

  Here, in the vehicle control apparatus 100 according to the present embodiment, the eco-run control is performed as described above. When the engine is restarted by the eco-run control, a large amount of electric power is consumed by the starter motor 26, so that the supply voltage from the battery 24 to the EPS ECU 22 decreases. As a result, the voltage at the point A becomes equal to or lower than the threshold value, and there is a possibility that the EPS ECU 22 may erroneously determine that an abnormality has occurred although no abnormality such as disconnection has occurred. When an erroneous determination of abnormality occurs, the supply of power to the power steering motor 28 is stopped and the electric power steering apparatus cannot be started, so that a large force is required for steering, and the driver is uncomfortable.

  Hereinafter, erroneous determination of abnormality will be described based on specific numerical values. Here, the minimum voltage of the battery 24 at normal time is 11 V, the internal resistance of the battery 24 is 20 mΩ, the wiring resistance of the wire harnesses 30 and 31 is 22 mΩ, and the maximum value of the current drawn by the EPS ECU 22 is 60 A. Note that the normal time here refers to a state in which the engine 14 is driven, not in the eco-run control. When the engine 14 is driven, an alternator (not shown) provided in the engine 14 is rotating, so that the voltage of the battery 24 does not fluctuate greatly.

Under normal conditions, the minimum voltage VAmin at the point A of the EPSECU 22 is 8.36 V as follows.
VAmin = 11−60 × (0.02 + 0.022) = 8.36V
When the power input plus terminal 22a is opened, the voltage at the point A is about 4.3V obtained by subtracting 0.7V corresponding to the voltage drop due to the diode 52 from 5V. Further, when the first MOSFET 46 fails, the potential at point A becomes the ground potential (about 0 V). Therefore, if the threshold voltage for determining abnormality is set to, for example, 5 V between 4.3 V and 8.36 V, abnormality can be determined.

Next, A point voltage at the time of engine restart by eco-run control will be examined. Since the alternator is stopped during the eco-run control, the output voltage of the battery 24 is lowered by supplying large electric power to the starter motor 26 in order to restart the engine 14. Here, it is assumed that the minimum voltage of the battery 24 is reduced to 7.2 V by engine restart. In this case, the minimum voltage VAmin at the point A of the EPSECU 22 is 4.56 V as follows.
VAmin = 7.2-60 × (0.02 + 0.022) = 4.56V
Therefore, when the engine 14 is restarted during the eco-run control, VAmin becomes 5 V or less which is a threshold value for determining abnormality, and thus the EPS ECU 22 erroneously determines that abnormality has occurred.

  Therefore, in the present embodiment, the abnormality determination unit 32 detects the abnormality when the eco-run ECU 10 is restarting the engine 14 while the eco-run ECU 10 is executing the eco-run control. Is changed from a predetermined first threshold voltage in the normal state to a predetermined second threshold voltage in consideration of a drop in the supply voltage. For example, specifically, the abnormality determination unit 32 sets the threshold voltage to the first threshold voltage described above when an engine restart command signal is output from the eco-run ECU 10 to the engine ECU 12 while the eco-run ECU 10 is executing the eco-run control. = 5V is changed to a value lower than the first threshold voltage, for example, a second threshold voltage between 4.56V and 4.3V = 4.4V. Thereby, even when the engine 14 is restarted during the eco-run control, the occurrence of erroneous determination of an abnormality is prevented, and the electric power steering device can be activated even during the eco-run control. The second threshold voltage may be appropriately determined by experiment or simulation so that an erroneous determination of abnormality does not occur when the supply voltage decreases, according to the circuit configuration of the EPSECU 22 or the like.

  FIG. 3 is a flowchart for explaining the process of the abnormality determination unit 32 according to the present embodiment. This process is executed at a predetermined cycle.

When the process is started, the abnormality determination unit 32 of the EPS ECU 22 first receives the eco-run control mode from the eco-run ECU 10 (S10). In this eco-run control mode, one of the following signals 1 to 4 is selected and transmitted from the eco-run ECU 10 to the abnormality determination unit 32 based on various signals indicating the operating state of the engine received from the engine ECU 12. is there.
Signal 1: Engine on state Signal 2: Fuel cut in progress Signal 3: Engine stop state by eco-run control Signal 4: Engine restarting

  The abnormality determination unit 32 determines whether or not the eco-run control is being performed based on the eco-run control mode received from the eco-run ECU 10 (S12). Specifically, the abnormality determination unit 32 determines that the eco-run control is not being performed when the signal 1 is received, and determines that the eco-run control is being performed when the signals 2 to 4 are received.

  When it is determined that the eco-run control is not being performed (N in S12), the abnormality determination unit 32 sets the threshold voltage for determining abnormality to the first threshold voltage in the normal state (S14).

  On the other hand, when it is determined that the eco-run control is being performed (Y in S12), the abnormality determination unit 32 determines whether or not the engine 14 is being restarted based on the received eco-run control mode (S16). Specifically, the abnormality determination unit 32 determines that the engine 14 is not restarting when the signal 2 or 3 is received, and that the engine 14 is restarting when the signal 4 is received. judge.

  When it is determined that the engine 14 is not restarting (N in S16), the abnormality determination unit 32 sets the threshold voltage to the first threshold voltage during normal operation (S20). On the other hand, when it is determined that the engine is being restarted (Y in S16), the abnormality determination unit 32 sets the threshold voltage to the second threshold voltage in consideration of the drop in the supply voltage (S18). Thereby, the erroneous determination of abnormality in EPSECU22 is prevented.

  The present invention has been described above based on the embodiment. It should be understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention.

  In the above-described embodiment, the eco-run ECU 10 is configured to change the threshold voltage for determining an abnormality when the eco-run ECU 10 detects that the engine 14 is restarting while the eco-run control is being executed. However, the embodiment of the present invention is not limited to this, and is configured to change the threshold voltage when the eco-run ECU 10 detects that the voltage supplied to the EPS ECU 22 decreases during the execution of the eco-run control. That's fine. For example, the abnormality determination unit 32 may be configured to exchange information with a control device for a power window or an air conditioner, and to change the threshold voltage when the power window or the air conditioner is operated. Thereby, even when the auxiliary machine that consumes large electric power during the eco-run control is activated and the voltage supplied to EPSECU 22 decreases, it is possible to prevent erroneous determination of abnormality.

It is a block diagram which shows the vehicle control apparatus which concerns on embodiment of this invention. It is a figure which shows a part of internal circuit of EPSECU. It is a flowchart for demonstrating the process of the abnormality determination part which concerns on this Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Eco-run ECU, 12 Engine ECU, 14 Engine, 16 ABS ECU, 22 EPSECU, 24 Battery, 26 Starter motor, 28 Power steering motor, 40 Booster circuit, 32 Abnormality determination part, 100 Vehicle control apparatus.

Claims (2)

An eco-run control unit that executes eco-run control to temporarily stop the engine when a predetermined stop condition is satisfied;
An electric power steering controller that applies a steering assist force to the steering system by driving a motor;
An abnormality determination unit that monitors a voltage at a predetermined position in an internal circuit of the electric power steering control unit and determines that an abnormality has occurred in the electric power steering control unit when the voltage is equal to or lower than a predetermined threshold voltage; ,
With
When the abnormality determination unit detects that the voltage supplied to the electric power steering control unit decreases while the eco-run control unit is executing the eco-run control, the abnormality determination unit normally sets the threshold voltage for determining the abnormality. A vehicle control device that changes from a predetermined first threshold voltage to a predetermined second threshold voltage in consideration of a drop in supply voltage.   When the eco-run control unit detects that the eco-run control unit is restarting the engine while the eco-run control unit is executing the eco-run control, the abnormality determination unit sets the threshold voltage for determining the abnormality at a normal time. The vehicle control device according to claim 1, wherein the predetermined first threshold voltage is changed to a predetermined second threshold voltage in consideration of a drop in supply voltage.

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