JP6178253B2 - Vehicle system - Google Patents

Description

  The present invention relates to a vehicle system including an electric power steering device.

  There is known a technique for improving fuel efficiency and suppressing exhaust gas by performing idling stop (automatically stopping an engine) when stopping a vehicle in response to a driver depressing a brake pedal.

  For example, in Patent Document 1, when the rotational speed of an electric motor that assists the driver's steering force is equal to or less than a predetermined value and the steering torque detected by a torque sensor is equal to or less than a predetermined value, electric power steering It is described that it is determined that the power consumption of the device is small, and the control device allows the transition to idling stop. In the invention described in Patent Document 1, when it is almost certain that the driver has stopped steering, the control device allows an idling stop.

International Publication No. 2011/040494

By the way, a technique is known in which the behavior of a vehicle (hereinafter referred to as vehicle behavior) is estimated based on a detection value of a yaw rate sensor or the like, and an auxiliary steering torque by an electric motor is corrected according to the vehicle behavior. For example, when the vehicle behavior becomes unstable, the steering handle is prevented from being overcut by increasing the load when operating the steering handle.
However, Patent Document 1 does not describe a technology that associates stabilization of vehicle behavior using an electric power steering device with control of the idling stop described above. There is room for driving and stopping the engine more appropriately by performing control in association with stabilization of vehicle behavior and idling stop control.

  Therefore, an object of the present invention is to provide a vehicle system that stabilizes vehicle behavior and appropriately drives and stops the engine.

As means for solving the above-mentioned problems, the present invention includes an electric power steering device that has a motor that generates an auxiliary steering torque according to a steering torque that acts on a steering member, and that steers steered wheels, A vehicle system comprising: steering control means for controlling an electric power steering device; engine control means for stopping idling by stopping the engine when a predetermined condition is satisfied; and vehicle behavior detection means for detecting vehicle behavior. The generated electric power accompanying the driving of the engine is charged to the battery, the electric power from the battery is supplied to the motor, and the steer control means has a vehicle behavior based on the detection value of the vehicle behavior detection means. If unstable, correct the current corresponding to the auxiliary steering torque from the normal control to stabilize the vehicle behavior. Shifts to both the behavior stabilization control, traveling the road surface friction coefficient is smaller than the normal road low μ road, when executing the vehicle stability control, the steering control means of the steering member by a driver a steering reaction force against the steering is generated by the auxiliary steering torque, when the current consumption of the motor due to the assist steering torque is greater than during the normal control, the engine control means prohibits the idling stop, When the vehicle behavior stabilization control is executed during traveling on a high μ road having a road surface friction coefficient larger than that of a normal road surface, the steering control means uses the auxiliary steering torque that assists the steering of the steering member by the driver. When the current consumption of the motor accompanying the auxiliary steering torque is smaller than that during the normal control, the engine control Stage is characterized by allowing the idling stop.

  According to such a configuration, when the vehicle behavior detected by the vehicle behavior detection means is unstable, the steering control means shifts from normal control to vehicle behavior stabilization control. Therefore, the vehicle behavior can be stabilized according to the state of the vehicle.

Further, for example, on a low μ road with a small road surface friction coefficient, the steering force required when the driver steers the steered wheels becomes very small. When the vehicle behavior stabilization control is executed on such a low μ road, the steering reaction force is controlled so as to counter the driver's steering force by making the motor current consumption larger than that during normal control by the steer control means. May be generated to stabilize vehicle behavior.
In the present invention, the engine control means prohibits idling stop when the current consumption of the motor becomes larger than that during normal control by performing vehicle behavior stabilization control. By prohibiting the idling stop in this way, the power generated by the engine is continuously charged in the battery. As a result, since the amount of charge of the battery is secured, the vehicle behavior stabilization control can be continued properly, and the engine can be driven and stopped appropriately.

  The steering control unit performs the correction by adding or subtracting a correction current based on the vehicle behavior detected by the vehicle behavior detection unit from the current corresponding to the auxiliary steering torque, and the engine control unit includes: After the vehicle behavior stabilization control, when the current consumption of the motor is larger than that during the normal control and the correction current is greater than or equal to the first threshold, the idling stop is prohibited and the idling stop is prohibited. It is preferable that the idling stop is allowed when the correction current is equal to or smaller than a second threshold value that is smaller than the first threshold value.

According to such a configuration, the engine control means prohibits idling stop when the current consumption of the motor is larger than that during normal control and the correction current is equal to or greater than the first threshold value. Further, the engine control means allows the idling stop when the correction current becomes equal to or less than the second threshold value after prohibiting the idling stop.
Here, since the second threshold value is set to a value smaller than the first threshold value, it is possible to prevent the idling stop from being prohibited / allowed repeatedly (hunting). Moreover, it can suppress that charging / discharging of a battery is repeated frequently and can suppress the capacity | capacitance fall of a battery by extension.

  According to the present invention, it is possible to provide a vehicle system that stabilizes the vehicle behavior and appropriately drives and stops the engine.

It is explanatory drawing of the electric power steering apparatus with which the vehicle system which concerns on 1st Embodiment of this invention is provided. It is explanatory drawing which shows the connection relation of each structure with which a vehicle system is provided. It is a functional block diagram which shows the structure of an EPS control apparatus and an engine control apparatus. It is explanatory drawing which shows the relationship between the steering angle of a steering handle, and the steering force required for a driver | operator to steer a steering handle. It is a functional block diagram which shows the structure of a correction | amendment electric current calculation part. It is a flowchart which shows the process which a control apparatus performs. It is a flowchart which shows the process which the control apparatus with which the vehicle system which concerns on 2nd Embodiment of this invention is provided.

<< First Embodiment >>
<Vehicle system configuration>
FIG. 1 is an explanatory diagram of an electric power steering apparatus provided in the vehicle system according to the present embodiment. The vehicle system 1 (see FIG. 2) includes an electric power steering device 10 shown in FIG. 1, sensors (vehicle speed sensor 25, etc.), an EPS control device 30 (Electric Power Steering), and an engine 41 (see FIG. 2). ACG 42 (Alternating Current Generator: see FIG. 2), a battery 44 (see FIG. 2), and an engine control device 50 (see FIG. 2).

(Electric power steering device)
The electric power steering device 10 is a device that steers the steered wheels K by steering torque that acts on the steering handle H (steering member) and auxiliary steering torque that is driven by the motor 16. The electric power steering apparatus 10 includes a main steering shaft 11, a connecting shaft 12, a pinion shaft 13, a rack shaft 14, a tie rod 15, a motor 16, and an inverter 17.

  The main steering shaft 11 is a shaft that rotates as the steering handle H is steered, and its upper end is fixed to the steering handle H. The connecting shaft 12 has two universal joints 12 a and 12 b that are universal joints, and is connected to the main steering shaft 11. The pinion shaft 13 is a shaft member connected to the connection shaft 12, and a pinion gear 13a is formed in the lower part thereof.

  The rack shaft 14 has rack teeth 14a meshing with the pinion gear 13a, and is installed to be movable in the vehicle width direction. The tie rod 15 connects both ends of the rack shaft 14 and knuckle arms (not shown) installed on the left and right steered wheels K (front wheels).

  The motor 16 is an electric motor for reducing the steering force required for steering the steering handle H or stabilizing the vehicle behavior. For example, a three-phase brushless motor can be used as the motor 16. A worm gear 18 for transmitting the driving force of the motor 16 to the pinion shaft 13 is installed on a rotor (not shown) of the motor 16. The worm gear 18 meshes with a worm wheel gear 19 installed on the pinion shaft 13.

  The inverter 17 has, for example, a three-phase bridge circuit (not shown) and is electrically connected to the motor 16. The inverter 17 generates a three-phase AC voltage corresponding to a PWM (Pulse Width Modulation) signal input from the EPS control device 30 and outputs it to the motor 16. The inverter 17 is provided with a current sensor 21 that detects the current value of the motor 16.

  When the motor 16 is driven by the three-phase AC voltage input from the inverter 17, the driving force is transmitted to the pinion shaft 13 via the worm gear 18 and the worm wheel gear 19. Then, when the pinion shaft 13 rotates, the rack shaft 14 moves in the vehicle width direction, and the steered wheels K are steered.

(Sensors)
The steering angle sensor 22 is a sensor that detects the steering angle from the neutral position with respect to the steering handle H, and is installed on the main steering shaft 11, for example.
The steering torque sensor 23 is a sensor that detects a steering torque that acts on the steering handle H, and is installed on the pinion shaft 13. As the steering torque sensor 23, for example, a pair of coils installed so that the magnetic flux density changes according to the steering handle H being steered can be used.
The motor rotation speed sensor 24 is a sensor that detects the rotation speed of the motor 16 and is built in the motor 16. As the motor rotation speed sensor 24, a hall sensor, a resolver, or the like can be used.

In addition, a vehicle speed sensor 25 for detecting the vehicle speed, a yaw angular velocity sensor 26 for detecting the vehicle yaw angular velocity (angular velocity around the vertical axis passing through the center of gravity of the vehicle body), and a lateral acceleration of the vehicle (side of the vehicle body) And a lateral acceleration sensor 27 for detecting a direction acceleration). The vehicle is also provided with a brake sensor 28 (see FIG. 3) that detects the amount of depression of a brake pedal (not shown).
The “vehicle behavior detecting means” for detecting the vehicle behavior includes a vehicle speed sensor 25, a yaw angular velocity sensor 26, and a lateral acceleration sensor 27.

(EPS control device)
FIG. 2 is an explanatory diagram illustrating a connection relationship of each component included in the vehicle system. In FIG. 2, illustration of the sensors described above is omitted.
As described above, the motor 16 included in the electric power steering apparatus 10 and the inverter 17 are electrically connected.

The EPS control device 30 (steer control means) is a device that controls the electric power steering device 10 by driving the inverter 17 (see FIG. 3) in accordance with signals input from the above-described sensors.
The EPS control device 30 includes electronic circuits such as a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and various interfaces, and performs various functions according to programs stored therein. To do.
Further, the EPS control device 30 has a function of shifting from normal control to vehicle behavior stabilization control when the vehicle behavior based on the detection value of each sensor described above is unstable, and stabilizing the vehicle behavior by driving the motor 16. Also have. The stabilization of vehicle behavior will be described later.

The engine 41 is an internal combustion engine connected to an axle (not shown) via a speed reducer (not shown) and a differential gear (not shown). The engine 41 is driven by the engine control device 50, and the vehicle travels when an accelerator pedal (not shown) is further depressed.
The ACG 42 is an AC generator that generates power using the power of the engine 41, and is connected to the battery 44 via the converter 43.

  The converter 43 is a power converter that converts AC power input from the ACG 42 into DC power. The inverter 17 and the converter 43 may be integrated to form an inverter / converter.

The battery 44 is, for example, a lithium ion battery, and is electrically connected to the inverter 17 and the converter 43. When the inverter 17 is driven in accordance with a command from the EPS control device 30, the electric power stored in the battery 44 is taken out and this electric power is supplied to the motor 16.
Further, when regenerative braking is performed during deceleration of the vehicle, or when the engine 41 is driven during idling stop, the ACG 42 is driven to generate electricity. The generated power (AC power) of the ACG 42 is converted into DC power by the converter 43, and the DC power is charged in the battery 44.

  The engine control device 50 (engine control means) is a device that controls the driving of the engine 41 in accordance with the amount of depression of an accelerator pedal (not shown). Specifically, the engine control device 50 includes a throttle valve (not shown) that adjusts the intake air amount of the engine 41, an injector (not shown) that injects fuel gas, and an ignition plug (not shown) that ignites the fuel. ) Etc.

The engine control device 50 has a function of stopping the engine 41 to stop idling when a predetermined stop condition (predetermined condition) is satisfied. Here, the “stop condition” is, for example, a condition that the vehicle speed is equal to or less than a predetermined value and a brake pedal (not shown) is depressed.
The engine control device 50 also has a function of restarting the engine 41 when a predetermined start condition is satisfied. Here, the “starting condition” is, for example, a condition that an accelerator pedal (not shown) is depressed or a condition that a foot is released from a brake pedal (not shown).

(Configuration of EPS control device)
FIG. 3 is a functional block diagram showing configurations of the EPS control device and the engine control device.
As shown in FIG. 3, the EPS control device 30 includes a target assist current calculation unit 31, a correction current calculation unit 32, a motor drive control unit 33, and a flag setting unit 34.
The target assist current calculation unit 31 is based on the steering torque Ts detected by the steering torque sensor 23, the motor rotation speed Nm detected by the motor rotation speed sensor 24, and the vehicle speed V detected by the vehicle speed sensor 25. Then, a target assist current I _MO (current corresponding to the assist steering torque) for generating the assist steering torque is calculated.

For example, the target assist current calculation unit 31, together with the steering torque Ts is larger target assist current I _MO as large, was set tables (shown to reduce the target assist current I _MO as the vehicle speed V increases Z). Target assist current calculation unit 31 refers to this table and calculates the target assist current I _MO corresponding to the detected value of each sensor.

The correction current calculation unit 32 is based on the vehicle speed V detected by the vehicle speed sensor 25, the yaw angular velocity Y detected by the yaw angular velocity sensor 26, and the lateral acceleration Lg detected by the lateral acceleration sensor 27. A correction current I _D for correcting the current I _MO is calculated.
For example, the vehicle behavior may be temporarily unstable while traveling on a slippery road surface (so-called low μ road) having a small road surface friction coefficient. In such a case, the correction current calculation unit 32 estimates the vehicle behavior based on the vehicle speed V, the yaw angular velocity Y, and the lateral acceleration Lg, and calculates a correction current _ID for stabilizing the vehicle behavior.

As will be described later, the correction current _ID is added or subtracted from the target assist current _IMO in the subtractor 35 (this value is referred to as the target motor current _IMT ). That is, the larger the correction current _ID , the smaller the target motor current _{IMT, and} the smaller the auxiliary steering force of the motor 16 (the steering handle H becomes heavier). Thus, the driver is warned not to turn the steering handle H too much, and the vehicle behavior is stabilized by suppressing the yaw angular velocity and the like.
When the vehicle behavior is stable, the correction current I _D = 0, and when the unstable vehicle behavior is stabilized, the correction current I _D > 0.

Hereinafter, such control that generates the correction current _ID and stabilizes the vehicle behavior is referred to as “vehicle behavior stabilization control”. Further, the control for generating the auxiliary steering torque when the vehicle behavior is stable (correction current I _D = 0) is referred to as “normal control”.

FIG. 4 is an explanatory diagram showing the relationship between the steering angle of the steering handle and the steering force required for the driver to steer the steering handle.
First, consider a case where the driver steers the steering handle H by the steering angle θ1 while traveling on a high μ road with a large road surface friction coefficient. When the vehicle behavior is stable and the correction current I _D = 0, the target assist current I _MO becomes the target motor current I _MT as it is (see FIG. 3). In this case, the steering force required for steering the steering handle H is represented by a curve (solid line) shown as “steering force at high μ” in FIG.

In addition, when the vehicle behavior becomes unstable while the vehicle is running, the steering force for warning the driver that the steering handle H is too cut off (to make the steering handle H heavy) is F _A.
As described above, the road friction coefficient is relatively large on the high μ road. Therefore, by reducing the target motor current I _MT (I _MT = I _MO −I _D > 0: see FIG. 3) and reducing the auxiliary steering torque, the steering force required for turning is reduced from F1 to F. Can be pulled up to _A (arrow α). As a result, the driver notices that the steering handle H is heavy, and the steering handle H is prevented from being overcut. In this case, the current consumption of the motor 16 is smaller than that during normal control.
Incidentally, the case where the correction current _ID is set so that the target motor current I _MT = 0 in this state is shown as “manual steering force at high μ” (broken line) in FIG. In this case, the auxiliary steering force becomes zero, and a force exceeding the steering force F1 is required to obtain the steering angle θ1 (the steering handle H is too heavy).

Next, consider a case where the driver steers the steering handle H by the steering angle θ1 while traveling on a low μ road with a small road surface friction coefficient. When the vehicle behavior is stable and the correction current I _D = 0, the steering force required to steer the steering handle H is represented by a curve (solid line) shown as “steering force at low μ” in FIG. On a low μ road, the steering force F2 required to obtain the steering angle θ1 is also very small compared to the steering force F1 at high μ.

Further, the case where the correction current _ID is set so that the target motor current I _MT = 0 on the low μ road is shown as “manual steering force at low μ” (broken line) in FIG. On the low μ road, even when the target motor current I _MT = 0, the steering force F3 often does not reach the steering force F _A for warning the driver that the steering handle H is overcut. That is, even when there is no auxiliary steering force by the motor 16, the steering handle H is increased by the driver's steering force, and the vehicle behavior may be further destabilized.

In order to stabilize the vehicle behavior to avoid such a situation, the correction current calculation unit 32, by increasing the correction current I _D than the target assist current I _MT, the target motor current I _MT to a negative value _{(I MT = I MO -I D} <0). Then, by making the absolute value | _IMT | of the target motor current _IMT larger than that during normal control, a steering reaction force against the steering force of the driver is generated by the motor 16. As a result, the steering force required to steer the steered wheels K is raised from F3 to F _A (arrow β), and the steering handle H is not easily increased. In this case, the current consumption of the motor 16 is larger than that during normal control.

Next, processing when the correction current calculation unit 32 calculates the correction current _ID will be described in detail. FIG. 5 is a functional block diagram showing the configuration of the correction current calculation unit.
As illustrated in FIG. 5, the correction current calculation unit 32 refers to the control gain map 32 a based on the vehicle speed V input from the vehicle speed sensor 25 and acquires the gain Km corresponding to the vehicle speed V. The control gain map 32a is set so that the gain Km decreases as the vehicle speed V increases.
Then, the yaw angular velocity Y inputted from the yaw angular velocity sensor 26 and the gain Km described above are multiplied by the multiplier 32b to calculate the value X1. The value X1 increases as the yaw angular velocity Y increases and the vehicle speed V decreases.

  Further, the gain Km is subtracted from “1” in the subtractor 32c. The subtracted value is multiplied by the lateral acceleration Lg input from the lateral acceleration sensor 27 by the multiplier 32d, thereby calculating a value X2. The value X2 increases as the lateral acceleration Lg increases and the vehicle speed V increases. Then, the value X1 and the value X2 are added by the adder 32e, and the value X3 is calculated. The greater the value X3, the greater the degree of instability of the vehicle behavior.

Further, the correction current calculation unit 32 refers to the offset map 32g and acquires the offset value Ofs corresponding to the vehicle speed V. Then, the value X4 is calculated by subtracting the value X3 from the offset value Ofs by the subtractor 32f. Further, the correction current calculation unit 32 refers to the reference correction current map 32h and calculates the reference correction current I _mb corresponding to the value X4.
Further, the correction current calculation unit 32 refers to the ratio map 32i and acquires the ratio Rto corresponding to the vehicle speed V. The correction current I _D is calculated by multiplying the reference correction current I _mb and the ratio Rto by the multiplier 32j.

Returning again to FIG. 3, the description will be continued. Subtractor 35 of the EPS control apparatus 30, by subtracting the correction current I _D from the target assist current I _MO, calculates the target motor current I _MT. As described above, the correction current _ID is set to be larger than zero so that the steering handle H becomes heavy, and the driver is warned that the steering handle H is too cut.

Subtractor 36, a current detection value I _F inputted from the current sensor 21, and calculates the deviation ΔI by subtracting from the target motor current I _MT.
The motor drive control unit 33 performs PI control so that the deviation ΔI input from the subtractor 36 is zero, and generates a PWM signal. The motor 16 is driven by the PWM signal generated by the motor drive control unit 33 being input to the inverter 17.
By performing such control, the EPS control device 30 executes the above-described normal control (I _D = 0) or vehicle behavior stabilization control (I _D > 0) while assisting the steering torque by the driver. .

The flag setting unit 34 determines whether or not the current consumption of the motor 16 is larger than that during normal control, and outputs an idling stop prohibition flag Fg to the stop / start control unit 51. As the “current consumption of the motor 16”, the absolute value | I _MT | of the target motor current I _MT may be used (see FIG. 3), or the absolute value | I _F | of the detected current value I _F may be used. Also good.

As described above, when the vehicle behavior becomes unstable while traveling on a high μ road, the target motor current I _MT (> 0) is made smaller than that during normal control, and the driver's steering force required for steering is reduced. Often pulled up (see arrow α in FIG. 4). In this case, even when the engine 41 is automatically stopped and idling is stopped, the current supplied from the battery 44 to the motor 16 may be smaller than that during normal control. That is, there is no possibility that the remaining capacity (SOC: State Of Charge) of the battery 44 is greatly reduced or that a problem occurs when the engine 41 is restarted.

Therefore, when the vehicle behavior stabilization control is executed with the correction current _ID larger than zero and the current consumption of the motor 16 is equal to or lower than that during the normal control, the flag setting unit 34 sets the idling stop prohibition flag Fg. Turn off. Then, the flag setting unit 34 outputs the prohibition flag Fg to the stop / start control unit 51.
Even during normal control when vehicle behavior stabilization control is not performed (I _D = 0), the flag setting unit 34 turns off the prohibition flag Fg.

Further, as described above, if the vehicle behavior during traveling of the low μ road becomes unstable, usually the absolute value of the target motor current I _MT than during control | I _MT | a by increasing the operating required for steering The steering force of the person is often raised (see arrow β in FIG. 4). In this case, if the engine 41 is automatically stopped to perform idling stop, the current consumption of the motor 16 becomes larger than that during normal control. As a result, the remaining capacity of the battery 44 may be greatly reduced, or the engine 41 may not be restarted properly thereafter.

Therefore, when the vehicle behavior stabilization control is executed by setting the correction current _ID to be larger than zero and the consumption current of the motor 16 is larger than that during the normal control, the flag setting unit 34 sets the idling stop prohibition flag Fg. Turn on.

(Configuration of engine control device)
As shown in FIG. 3, the engine control device 50 includes a stop / start control unit 51 and an engine drive control unit 52.
The stop / start control unit 51 controls the engine 41 to stop (idling stop) and restart, and includes an engine stop control unit 51a and an engine start control unit 51b.

Whether the engine stop control unit 51a satisfies the stop condition based on the vehicle speed V detected by the vehicle speed sensor 25 and the depression amount S of a brake pedal (not shown) detected by the brake sensor 28. Determine whether or not.
When the prohibition flag Fg: OFF signal is input from the flag setting unit 34, the engine stop control unit 51a outputs a signal to the engine drive control unit 52 that allows idling stop based on the establishment of the stop condition. .
On the other hand, when the prohibition flag Fg: ON signal is input from the flag setting unit 34, the engine stop control unit 51a outputs a signal to the engine drive control unit 52 to prohibit idling stop.

Whether the engine start control unit 51b satisfies the start condition based on the vehicle speed V detected by the vehicle speed sensor 25 and the depression amount S of a brake pedal (not shown) detected by the brake sensor 28. Determine whether or not.
When the start condition is satisfied, the engine start control unit 51b outputs a signal to the engine drive control unit 52 to restart the engine 41 from the idling stop state. Incidentally, the restart of the engine 41 is based on the premise that the prohibition flag Fg is turned off (idling stop is allowed).

The engine drive control unit 52 executes the stop / restart of the engine 41 in accordance with a signal input from the engine stop control unit 51a or the engine start control unit 51b. The details of the process executed by the engine drive control unit 52 are omitted.
Hereinafter, the EPS control device 30 and the engine control device 50 may be simply referred to as “control device”.

<Operation of control device>
FIG. 6 is a flowchart illustrating processing executed by the control device. Note that it is assumed that the engine 41 is driven in “START” in FIG. 6 and the electric power steering device 10 generates auxiliary steering torque.
In step S <b> 101, the control device determines whether or not the vehicle behavior is stable by the EPS control device 30. That is, the control device determines whether or not the value of the correction current _ID output from the correction current calculation unit 32 (see FIG. 3) is greater than zero.

When the vehicle behavior is stable, that is, when the correction current I _D = 0 (S101 → Yes), the control device proceeds to step S102.
In step S <b> 102, the control device performs normal control by the EPS control device 30. As described above, the “normal control” is a control for generating the auxiliary steering torque in a state where the vehicle behavior is stable (correction current I _D = 0). During the execution of the normal control, the control device appropriately performs automatic stop / restart of the engine according to the establishment of the stop condition / start condition described above. After performing the process of step S102, the process of the control device returns to “START” (RETURN).

If the vehicle behavior is not stable in step S101, that is, if the correction current I _D > 0 (S101 → No), the process of the control device proceeds to step S103.
In step S <b> 103, the control device performs vehicle behavior stabilization control by the EPS control device 30. That is, the control device calculates the correction current _ID according to the detection values of the vehicle speed sensor 25 (see FIG. 3), the yaw angular velocity sensor 26, and the lateral acceleration sensor 27. Then, the controller performs a feedback control to match the current detection value I _F of the motor 16 to the target motor current _{I MT (= I MO -I D} ). As a result, the load torque of the steering handle H is increased, and the vehicle behavior is stabilized.

Controller in step S104, the flag setting unit 34 (see FIG. 3), the above-mentioned normal current consumption of the motor 16 than during the control run (e.g., the absolute value of the target motor current I _MT | I _MT |) is large It is determined whether or not.

If the current consumption of the motor 16 is larger than that during normal control (S104 → Yes), the control device proceeds to step S105. Note that when the current consumption of the motor 16 is larger than that during normal control, for example, the vehicle behavior becomes unstable during traveling on a low μ road, and the motor 16 generates a steering reaction force against the steering force of the driver. This is the case.
As described above, the steered wheels K are slippery on the low μ road, and the steering handle H may be increased only by the driver's steering force even when the motor 16 is not driven at all. By making the consumption current of the motor 16 larger than that during normal control and generating a steering reaction force, it is possible to prevent the steering handle H from being overcut.

In step S105, the control device turns on the idling stop prohibition flag Fg by the flag setting unit 34 (see FIG. 3).
In step S106, the control device prohibits idling stop by the engine stop control unit 51a (see FIG. 3). That is, the control device performs vehicle behavior stabilization control while driving the engine 41 and the ACG 42. By continuing driving of the engine 41 in this way, the battery 44 can be continuously charged by the ACG 42 (see FIG. 2). After performing the process of step S106, the process of the control device returns to “START” (RETURN).

When the current value of the motor 16 is not larger than that in the normal control in step S104 (S104 → No), the control device proceeds to step S107.
In step S107, the control device turns off the idling stop prohibition flag Fg by the flag setting unit 34 (see FIG. 3).

  In step S108, the control device allows idling stop. That is, the control device stops the engine 41 and stops idling when the aforementioned stop condition is satisfied, and then restarts the engine 41 when the start condition is satisfied. After performing the process of step S108, the process of the control device returns to “START” (RETURN).

<Effect>
According to the present embodiment, when the vehicle behavior is unstable (S101 → No), the control device executes vehicle behavior stabilization control (S103). For example, on a low μ road where the steered wheel K is slippery, a reaction force against the steering force of the driver is generated by the motor 16 according to the detection value of each sensor. By making the steering handle H heavier in this way, the driver can be warned not to turn the steering handle H too much, and the vehicle behavior can be stabilized.

  When the current consumption of the motor 16 is larger than that during normal control (S104 → Yes), the control device prohibits idling stop (S106). Thereby, even if a relatively large current is consumed by the motor 16 in order to generate a steering reaction force against the driver's steering force, it is possible to suppress a decrease in the remaining capacity of the battery 44. As a result, it is possible to prevent a decrease in the capacity of the battery 44 or to avoid a situation in which the remaining capacity of the battery 44 is extremely decreased and the engine 41 cannot be restarted.

<< Second Embodiment >>
In the second embodiment, the threshold value Ia of the correction current _{ID as} a criterion for determining whether or not the idling stop is prohibited, and the threshold value Ib of the correction current _{ID as} a criterion for determining whether or not the idling stop is permitted again. Is different from the first embodiment. Therefore, a different part from 1st Embodiment is demonstrated and description is abbreviate | omitted about the overlapping part.

FIG. 7 is a flowchart showing processing executed by the control device of this embodiment. Note that the processing in steps S101 to S108 shown in FIG. 7 is the same as the processing in steps S101 to S108 in the flowchart (see FIG. 6) described in the first embodiment, and thus description thereof is omitted.
When the consumption current of the motor 16 is larger than that during normal control in step S104 (S104 → Yes), the control device proceeds to step S201.

In step S201, the control device determines whether or not the correction current _ID is greater than or equal to the threshold value Ia. Here, the threshold value Ia (first threshold value) is a value serving as a criterion for determining whether or not idling stop is prohibited, and is set in advance. If the correction current _ID is greater than or equal to the threshold value Ia (S201 → Yes), the control device proceeds to step S105. On the other hand, when the correction current _ID is less than the threshold value Ia (S201 → No), the process of the control device proceeds to step S107.

  After prohibiting idling stop in step S106, in step S202, the control device determines whether or not a predetermined time Δt (for example, several milliseconds) has elapsed since prohibiting idling stop. When the predetermined time Δt has not elapsed (S202 → No), the control device repeats the process of step S202. On the other hand, when the predetermined time Δt has elapsed (S202 → Yes), the control device proceeds to step S203.

In step S203, the control device determines whether or not the correction current _ID is equal to or less than the threshold value Ib. Here, the threshold value Ib (second threshold value:> 0) is a value that is a criterion for determining whether or not the idling stop once prohibited is permitted, and is set to a value smaller than the threshold value Ia used in step S201. . By making the threshold value Ib less than the threshold value Ia, it is possible to prevent the idling stop prohibition / permission from being repeated in a short time.

When the correction current _ID is equal to or smaller than the threshold value Ib (S203 → Yes), the control device proceeds to step S204. On the other hand, when the correction current _ID is larger than the threshold value Ib (S203 → No), the control device returns to step S105.
In step S204, the control device switches the idling stop prohibition flag Fg from on to off.
In step S205, the control device allows idling stop. That is, the control device stops the engine 41 when the aforementioned stop condition is satisfied, and restarts the engine 41 when the start condition is satisfied thereafter. After performing the processing of step S205, the control device returns to “START” (RETURN).

<Effect>
In the present embodiment, the threshold value Ib of the correction current _{ID that is} a criterion for allowing idling stop is set to a value smaller than the threshold value Ia that is a criterion for prohibiting idling stop. Thereby, it is possible to prevent the idling stop prohibition / permission from being repeated (hunting) in a short time. Therefore, frequent charging / discharging of the battery 44 can be suppressed, and as a result, a decrease in the capacity of the battery 44 can be suppressed.

  When the engine 41 is restarted, the ACG 42 (or another motor) is caused to function as a starter motor, so that a relatively large amount of power is consumed. By preventing the hunting described above, useless restart of the engine 41 can be suppressed, and the charging power of the battery 44 can be used efficiently. Furthermore, by preventing hunting, the power supply from the battery 44 to the motor 16 is also stably performed, so that the vehicle behavior stabilization control can be appropriately executed by the motor 16.

≪Modification≫
As mentioned above, although each embodiment demonstrated the vehicle system 1 which concerns on this invention, this invention is not limited to these description, A various change can be made.
For example, in each embodiment, the case where it is determined whether or not the stop condition / start condition is satisfied based on the detection values of the vehicle speed sensor 25 (see FIG. 3) and the brake sensor 28 has been described. Absent. That is, in addition to the detection values of the sensors described above, determination processing regarding the stop condition / start condition is performed based on the detection value of an accelerator sensor (not shown) that detects the stroke amount of an accelerator pedal (not shown). It may be.

In each embodiment, the case where the EPS control device 30 executes the vehicle behavior stabilization control according to the detection values of the vehicle speed sensor 25 (see FIG. 1), the yaw angular velocity sensor 26, and the lateral acceleration sensor 27 has been described. However, it is not limited to this. For example, based on the vehicle speed detected by the vehicle speed sensor 25, the steering angle detected by the steering angle sensor 22, and the yaw angular velocity detected by the yaw angular velocity sensor 26, the front steered wheel K and the rear steered wheel. The slip angle difference with K is calculated. Then, based on the slip angle difference, the vehicle state (oversteer / understeer) may be detected, and the correction current _ID may be calculated according to the result.

DESCRIPTION OF SYMBOLS 1 Vehicle system 10 Electric power steering apparatus 16 Motor 17 Inverter 25 Vehicle speed sensor (vehicle behavior detection means)
26 Yaw angular velocity sensor (vehicle behavior detection means)
27 Lateral acceleration sensor (vehicle behavior detection means)
30 EPS control device (steer control means)
32 Correction current calculation unit 41 Engine 42 ACG
43 Converter 44 Battery 50 Engine control device (engine control means)
H Steering handle (steering member)
K steered wheel

Claims (2)

An electric power steering device having a motor for generating an auxiliary steering torque corresponding to the steering torque acting on the steering member, and for turning the steered wheels;
Steer control means for controlling the electric power steering device;
Engine control means for stopping idling by stopping the engine when a predetermined condition is satisfied;
Vehicle behavior detection means for detecting vehicle behavior, and a vehicle system comprising:
The generated power accompanying the driving of the engine is charged to the battery, and the electric power from the battery is supplied to the motor,
The steering control means includes
When the vehicle behavior based on the detection value of the vehicle behavior detection means is unstable, the normal control shifts to vehicle behavior stabilization control for correcting the current corresponding to the auxiliary steering torque to stabilize the vehicle behavior,
When the vehicle behavior stabilization control is executed during traveling on a low μ road where the road surface friction coefficient is smaller than that of a normal road surface, the steering control means applies the steering reaction force against the steering of the steering member by the driver. is generated by the steering torque, when the current consumption of the motor due to the assist steering torque is greater than during the normal control, the engine control means prohibits the idling stop,
When the vehicle behavior stabilization control is executed during traveling on a high μ road having a road surface friction coefficient larger than that of a normal road surface, the steering control means uses the auxiliary steering torque that assists the steering of the steering member by the driver. The vehicle system is characterized in that the engine control means allows the idling stop when the motor consumption current is smaller than that during the normal control and the current consumption of the motor accompanying the auxiliary steering torque is smaller than that during the normal control. . The steering control means includes
The correction is performed by adding or subtracting a correction current based on the vehicle behavior detected by the vehicle behavior detection means from the current corresponding to the auxiliary steering torque,
The engine control means includes
By the vehicle behavior stabilization control, when the current consumption of the motor is larger than that during the normal control and the correction current is greater than or equal to a first threshold, the idling stop is prohibited.
2. The vehicle system according to claim 1, wherein, after the idling stop is prohibited, the idling stop is permitted when the correction current becomes equal to or smaller than a second threshold value that is smaller than the first threshold value.

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