JP2021131072A - Idling stop control device - Google Patents

Abstract

To provide an idling stop control device for properly performing idling stop control.SOLUTION: In an engine ECU 40 which is employed to a vehicle having an engine 10, a lithium ion storage battery 32 and an ISG 22 for starting the engine 10, automatically stops the engine 10 accompanying the establishment of a prescribed automatic stop condition, and performs idling stop control for restarting the engine 10 by the ISG 22 accompanying the establishment of a prescribed restart condition after the automatic stop. The engine ECU comprises; a drive control part for driving the ISG 22 in a state that the ISG 22 can impart a rotation force to the engine 10 in the case of the traveling of the vehicle and before the establishment of the automatic stop condition; and a determination part for determining whether or not to permit the automatic stop of the engine 10 on the basis of a voltage change of the lithium ion storage battery 32 when the ISG 22 is driven by the drive control part, or a change in rotational speed of the engine 10.SELECTED DRAWING: Figure 4

Description

The present invention relates to an idling stop control device.

Efforts are being made to improve the fuel efficiency of vehicles by automatically stopping the engine when certain conditions such as when the vehicle is stopped (so-called idling stop). At the time of automatic stop, the engine is restarted by supplying electric power from the storage battery to the engine starting device. If the engine cannot be restarted due to insufficient voltage of the storage battery or the like at the time of automatic stop, it may affect other passing vehicles. Therefore, before executing the automatic stop, it is necessary to determine whether or not the restart by the storage battery is possible. For example, in a vehicle that implements automatic stop of Patent Document 1, in order to detect the state of the storage battery, the internal resistance of the storage battery is detected from the change in voltage when a pulse current is passed. Then, by comparing this internal resistance with the discriminant value, it is determined whether or not automatic stop can be performed.

Japanese Patent No. 4239620

By the way, when determining whether or not restarting with a storage battery is possible, it is conceivable to determine the state of the storage battery with a margin. Also in the configuration of Patent Document 1, it is considered necessary to assign a margin estimated in advance to set a discriminant value and compare the discriminant value with the internal resistance. However, when the state of the storage battery is determined with a margin, it may be determined that the storage battery cannot be restarted even though the storage battery actually has electric power that can be restarted. In other words, you will lose the opportunity to carry out an automatic stop. Therefore, a more accurate determination method is required as to whether or not restarting with a storage battery is possible.

The present invention has been made in view of the above problems, and a main object thereof is to provide an idling stop control device for appropriately performing idling stop control.

The first means is applied to a vehicle including an engine, a battery, and a starting device driven by power supply from the battery to start the engine, and automatically stops the engine when a predetermined automatic stop condition is satisfied. It is an idling stop control device that performs idling stop control in which the engine is restarted by the starting device when a predetermined restart condition is satisfied after the automatic stop.
When the vehicle is running and before the automatic stop condition is satisfied, the drive control unit that drives the starting device under a state in which the starting device can apply a rotational force to the engine.
A determination unit that determines whether or not to allow automatic stop of the engine based on a change in the voltage of the battery or a change in the engine rotation speed when the starter is driven by the drive control unit.
To be equipped.

When the vehicle is running and before the automatic stop condition is satisfied, the voltage of the battery and the rotation speed of the engine change by applying the rotational force to the engine by driving the starting device. In this case, by performing a simulated restart operation by the starting device before the automatic stop of the engine is actually performed, the engine is restarted by the starting device from the change in the battery voltage and the engine rotation speed at that time. It is possible to grasp whether or not the start is performed properly. That is, by performing a simulated restart operation by the starting device, it is properly determined whether or not to allow the automatic stop of the engine based on the change in the voltage of the battery or the change in the engine rotation speed at that time. Can be done. At this time, since the configuration is such that whether or not the engine is automatically stopped is determined from the state when the starting device is actually driven, the margin for determining whether or not the engine can be automatically stopped can be reduced, and the chances of performing idling stop can be increased. As a result, idling stop control can be properly performed.

In the second means, the drive control unit determines that the speed of the vehicle reaches a predetermined speed higher than the vehicle speed condition included in the automatic stop condition at the time of deceleration of the vehicle. The rotational force is applied to the engine by driving the starting device.

When a simulated restart operation is performed by the starter, for example, if the battery voltage drops excessively due to the drive of the starter, or if the increase in engine speed is too small, automatic engine stop is permitted. Not done. In such a case, it may be difficult to return the engine to operation by driving the starting device. In this regard, when the vehicle is decelerating, the rotational force is applied to the engine by driving the starting device based on the fact that the vehicle speed reaches a predetermined speed higher than the vehicle speed condition included in the automatic stop condition. It was configured to be implemented. As a result, even if it is difficult to return the engine to operation by driving the starting device, it is possible to return to the operation of the engine by applying a rotational force from the axle.

In the third means, the vehicle is provided with a clutch that connects or shuts off a power transmission path between the engine and an axle that rotates with the wheels, and the engine is fuel-cut while the vehicle is running. The drive control unit is provided with a clutch control unit for disengaging the clutch, and the drive control unit is driven by the starting device after the clutch is disengaged by the clutch control unit and the rotation of the engine is stopped. Apply rotational force to the engine.

If the clutch is disengaged while the vehicle is running with fuel cut (so-called fuel cut during deceleration), the engine will rotate while the vehicle is still running. It will be stopped. In this case, after the rotation of the engine is stopped, it is possible to apply a rotational force to the engine by driving the starting device, that is, to perform a simulated restart operation by the starting device while the vehicle is running. Then, it is possible to properly determine whether or not to automatically stop the engine from the state when the starting device is driven.

In the fourth means, when the determination unit determines that the automatic stop of the engine is not permitted, the clutch is engaged, the rotational force is applied from the axle, and the fuel cut is released to release the engine. It is equipped with a return control unit that restores the operating state of the vehicle to its own state.

Even when the fuel is cut and the clutch is in the disengaged state, if the axle is in a predetermined rotational state due to vehicle running, the engine can be returned to operation by applying rotational force from the axle to the engine. It is possible. In this case, the operating state of the engine can be suitably returned to the self-sustaining state by engaging the clutch, applying a rotational force from the axle, and releasing the fuel cut.

In the fifth means, the starting device is a rotary electric machine that enables torque assist of the engine by power running drive, and the drive control unit is a torque in a state where the fuel of the engine is cut while the vehicle is running. As an assist, a rotational force is applied to the engine by driving the starting device, and the determination unit uses the change in the voltage of the battery or the change in the engine rotation speed when the torque assist is performed. Determines whether to allow automatic engine stop.

When the engine fuel cut is performed while the vehicle is running (so-called fuel cut during deceleration), the engine speed gradually decreases, but when the engine speed drops to the fuel cut release speed. Since the fuel cut is released, torque assist is performed by the starting device (rotary electric machine) in order to avoid it. In this case, it is possible to apply a rotational force to the engine by driving the starting device, that is, to perform a simulated restart operation by the starting device while the vehicle is running. Then, it is possible to properly determine whether or not to automatically stop the engine from the state when the starting device is driven.

In the sixth means, when the determination unit determines that the automatic stop of the engine is not permitted, the operating state of the engine is returned to the self-sustaining state by applying a rotational force from the axle and releasing the fuel cut. A return control unit is provided.

Even if the fuel is cut and the engine speed is gradually decreasing as the vehicle speed decreases, if the axle is in a predetermined rotational state due to vehicle running, the rotational force from the axle to the engine is applied. It is possible to return the engine to operation. In this case, the operating state of the engine can be suitably returned to the self-sustaining state by applying the rotational force from the axle and the starting device and releasing the fuel cut.

The seventh means includes an acquisition unit that acquires at least one of information such as the elapsed time from the previous determination, the vehicle mileage, and the battery power balance, which are determined by the determination unit to allow the automatic stop of the engine. The drive control unit applies rotational force to the engine by driving the starting device based on the information acquired by the acquisition unit when the vehicle is running and before the automatic stop condition is satisfied. ..

When a simulated restart operation is performed by the starting device, power consumption is generated by driving the starting device. Therefore, it is not desirable that the simulated restart operation by the starting device is excessively performed. In this regard, the rotational force is applied to the engine by driving the starting device based on at least one of the information of the elapsed time from the previous judgment, the vehicle mileage, and the battery power balance, which are determined to allow the automatic stop of the engine. Therefore, it is possible to suppress excessive power consumption while properly monitoring the state of the battery.

Schematic configuration diagram of the vehicle system of this embodiment Time chart explaining the timing of fuel cut control, extension control and idling stop control Flowchart for determining whether to allow idling stop control Time chart when automatic stop is allowed based on the voltage at restart Time chart when automatic stop is not allowed based on the voltage at restart Time chart when automatic stop is allowed based on engine speed at restart Flow chart for determining whether to allow automatic stop control during extension control Time chart when automatic stop is permitted based on the voltage during extension control Time chart when automatic stop is not permitted based on the voltage during extension control

<Embodiment>
Hereinafter, embodiments will be described with reference to the drawings. In the present embodiment, when the idling stop control device satisfies a predetermined automatic stop condition such as when the vehicle is stopped, the engine (internal combustion engine) is temporarily stopped, and the predetermined restart condition is satisfied after the automatic stop. , It is embodied as an engine ECU that implements idling stop control for restarting the engine.

FIG. 1 is a schematic configuration diagram of a vehicle system. The engine 10 is, for example, a multi-cylinder gasoline engine, and includes an injector, an ignition device, and the like (not shown). An automatic transmission 12 is connected to the crankshaft 11 of the engine 10. The automatic transmission 12 includes a lockup clutch 13 and a transmission 14, and shifts the rotation of the crankshaft 11 according to a gear ratio set each time and transmits the rotation to the output shaft 15.

An axle 17 is connected to the output shaft 15 via a differential gear 16. Wheels 18 are connected to the axle 17. Further, the wheels 18 are provided with a brake that applies a braking force to each wheel 18.

The lockup clutch 13 is composed of an electromagnetic clutch or a hydraulic clutch, and the connected state and the disconnected state are switched according to a control instruction. If the lockup clutch 13 is in the connected state, power can be transmitted between the crank shaft 11 and the output shaft 15 via the lockup clutch 13, and if the lockup clutch 13 is in the shutoff state, the power is locked. Power is not transmitted between the crank shaft 11 and the output shaft 15 via the up clutch 13. That is, the lockup clutch 13 is a mechanism for connecting or disconnecting the power transmission path between the engine 10 and the axle 17. The transmission 14 is composed of, for example, a well-known multi-stage transmission mechanism including a planetary gear mechanism, a CVT, or the like.

Further, an ISG (Integrated Starter Generator) 22 is connected to the crankshaft 11 of the engine 10 via a rotation transmission mechanism 21 composed of a plurality of pulleys, belts, and the like. The ISG 22 is a rotary electric machine having a power generation function driven by a crankshaft 11 to generate power. Further, the ISG 22 has an engine starting function of applying torque to the crankshaft 11 to start the engine 10 after warming up and the combustion of the engine 10 is stopped. Further, the ISG 22 has a torque assist function (output assist function) that assists the driving of the crankshaft 11 by applying torque to the crankshaft 11 from the outside after the engine 10 is started and while the vehicle is running. There is.

A ring gear 23 is connected to the crankshaft 11 of the engine 10. A starter 24 is mechanically connected to the crankshaft 11 via the ring gear 23. When the starter 24 starts when the IG switch is turned on, the starter 24 applies torque to the crankshaft 11 via the ring gear 23 to start the engine 10. Only one of the starter 24 and the ISG 22 may be provided as an engine starting device, or a motor generator (MG) may be provided in place of at least one of the ISG 22 and the starter 24.

The ISG 22 and the starter 24 are supplied with electric power by the vehicle-mounted power supply system 30 mounted on the vehicle. The in-vehicle power supply system 30 is a power supply system including a lead storage battery 31 and a lithium ion storage battery 32. The lead storage battery 31 is a well-known general-purpose storage battery. On the other hand, the lithium ion storage battery 32 is a high-density storage battery having a smaller power loss during charging / discharging, a higher output density, and a higher energy density than the lead storage battery 31. The rated voltage of each of these storage batteries 31 and 32 is the same, for example, 12V.

A starter 24 is connected to the lead-acid battery 31, and power is supplied from the lead-acid battery 31 to the starter 24. A lead storage battery 31 and a lithium ion storage battery 32 are connected in parallel to the ISG 22, and the storage batteries 31 and 32 can be charged and discharged by the ISG 22. The switch SW1 is provided on the electric path connecting the lead-acid battery 31 and the ISG 22, and the switch SW2 is provided on the electric path connecting the lithium ion storage battery 32 and the ISG 22. By controlling each switch SW1 and SW2 by the BMU (battery management unit) 35, charging / discharging between the ISG 22 and the storage batteries 31 and 32 is selectively performed.

The BMU 35 is a battery management device composed of a microcomputer including a CPU, a ROM, a RAM, an input / output interface, and the like. The BMU 35 acquires the state of the lithium ion storage battery 32 and outputs a signal (information) indicating the state of the lithium ion storage battery 32. The state of the lithium ion storage battery 32 is, for example, the output voltage and SOC of the lithium ion storage battery 32. The BMU 35 acquires the output voltage of the lithium ion storage battery 32 from the voltage sensor that detects the output voltage of the lithium ion storage battery 32, and outputs a signal (information) indicating the output voltage. The BMU 35 calculates the SOC and its change based on the charge / discharge current of the lithium ion storage battery 32, and outputs a signal (information) indicating the SOC.

An engine ECU 40 (hereinafter, simply referred to as ECU 40) is connected to the BMU 35. The BMU 35 is connected to the ECU 40 by a communication network such as CAN so that it can communicate with each other, and various data can be shared with each other.

The ECU 40 is an electronic control device including a well-known microcomputer including a CPU, ROM, RAM, flash memory, and the like. The ECU 40 is configured to be able to acquire various information. For example, the ECU 40 acquires driver operation information from various sensors such as an accelerator sensor that detects an accelerator operation amount and a brake sensor that detects a brake operation amount of a brake pedal. Further, the ECU 40 acquires information indicating the state of the lithium ion storage battery 32 from the BMU 35. Further, the ECU 40 acquires information about the vehicle (vehicle speed (vehicle speed), etc.) from various sensors such as a vehicle speed sensor.

Then, the ECU 40 executes various controls based on the acquired various information. For example, the ECU 40 controls the power running drive and power generation of the ISG 22 based on the vehicle speed, driver operation information, and the like. At that time, the ECU 40 controls charging and discharging of the lithium ion storage battery 32 based on the SOC of the lithium ion storage battery 32 and the like. Specifically, the ECU 40 instructs the BMU 35 of the battery unit U so that the SOC of the lithium ion storage battery 32 is maintained within a predetermined range of use.

Further, the ECU 40 controls the operating state (including start and stop) of the engine 10. For example, the ECU 40 performs stop control of fuel supply to the engine 10 (fuel cut control) and idling stop control of the engine 10 as control of the operating state of the engine 10.

As a general rule, the fuel cut control stops the supply of fuel to the engine 10 when the cut conditions such as the accelerator operation being released and the engine speed exceeding a certain level are satisfied, and then the engine speed is released. It is a control that restarts the supply of fuel to the engine 10 when the rotation speed is lowered. That is, the ECU 40 performs a fuel cut (fuel cut) on the engine 10 when the vehicle decelerates due to the accelerator being off.

When the engine rotation speed drops to the release rotation speed in the fuel cut state, the fuel cut is released, so that extension control for extending the fuel cut state should be implemented. For example, when the extension condition such as deceleration in a predetermined range is satisfied during the fuel cut control, the ECU 40 executes the extension control using the torque assist function by the ISG22. In this case, during the extension control, the crankshaft 11 is given rotation by the ISG 22, and the engine rotation speed is maintained, so that the fuel cut state is extended.

The idling stop control is generally a control in which the operation (combustion) of the engine 10 is stopped when a predetermined automatic stop condition is satisfied, and then the engine 10 is restarted when a predetermined restart condition is satisfied. The restart of the engine 10 is performed by power running drive of the ISG 22 by supplying power from the lithium ion storage battery 32.

The automatic stop condition includes, for example, that the vehicle speed is smaller than the automatic engine stop speed (for example, 10 km / h), the accelerator operation is released, or the brake operation is performed. The restart condition includes, for example, that the accelerator operation has been started and that the brake operation has been released. The ECU 40 also has a function of determining that the explosion has been completed (that is, the restart has been completed) after the engine 10 has been restarted. It is also possible to configure the engine control function such as fuel cut and the idling stop function to be performed by separate ECUs.

FIG. 2 is a time chart illustrating the timing of fuel cut control, extension control, and idling stop control.

In FIG. 2, during the acceleration period of timings t1 to t2, the engine 10 is in the combustion state and the ISG22 is in the torque assist state, and the vehicle is in the acceleration state due to the torque of these engines 10 and ISG22. After that, the period of timings t2 to t3 is a period in which the vehicle speed is constant, and while the engine 10 is maintained in the combustion state, the torque assist of the ISG 22 is stopped.

After that, after the timing t3, the vehicle is decelerated due to the accelerator off, the combustion of the engine 10 is stopped by the execution of the fuel cut, and the regenerative power generation by the ISG 22 is executed. When the engine speed reaches a predetermined value and the deceleration is smaller than the predetermined value at the timing t4, the torque assist by the ISG 22 is performed, and the fuel cut state is maintained accordingly. That is, extension control is implemented to extend the fuel cut period.

After that, when the vehicle speed drops to the automatic engine stop speed at the timing t5, the engine 10 is automatically stopped when the automatic stop condition is satisfied. Further, the ISG 22 is in a state of neither power generation nor power running. After that, when the restart condition is satisfied at the timing t6, the engine is restarted by the ISG22. In this way, fuel cut control, extension control, and idling stop control are implemented as the vehicle decelerates and stops.

By the way, at the time of restarting after the automatic stop of the engine 10, if the engine 10 cannot be restarted due to a power shortage of the lithium ion storage battery 32 or the like, the influence on other passing vehicles or the like occurs. Therefore, before executing the automatic stop, it is necessary to determine whether or not the restart by the lithium ion storage battery 32 is possible. Further, in order to secure the opportunity of automatic engine stop, it is necessary to properly grasp the state of the lithium ion storage battery 32.

Therefore, in the present embodiment, when the vehicle is running and before the automatic stop condition is satisfied, the ISG 22 is driven under a state in which the engine 10 can be subjected to a rotational force by the ISG 22 (that is, simulated by the ISG 22). The engine is restarted), and it is determined whether or not the automatic stop of the engine 10 is permitted based on the change in the battery voltage during the ISG drive.

FIG. 3 is a flowchart for determining whether idling stop control is permitted. The processing of this flowchart is executed by the ECU 40 at a predetermined cycle.

In S11, it is determined whether the vehicle is decelerating and the vehicle speed has reached a predetermined speed. More specifically, it is determined whether the vehicle speed is reduced to the extent that it can be said that it is immediately before the automatic stop is performed at the time of fuel cut to the engine 10 due to the deceleration of the vehicle. The predetermined speed is, for example, about 15 km / h, which is higher than the above-mentioned automatic engine stop speed, and is a speed at which the operation of the engine 10 can be restored by applying a rotational force to the engine 10 from the axle 17. Is. That is, it is determined whether or not the speed has reached a speed at which the combustion of the engine 10 can be restored by the rotation of the axle 17 immediately before the automatic stop.

If it is determined in S11 that the vehicle speed has not reached the predetermined speed (S11: No), that is, if it is not immediately before the automatic stop, the process ends. If it is determined in S11 that the vehicle speed has reached the predetermined speed (S12: Yes), that is, if it is immediately before the automatic stop, the process proceeds to S12.

In S12 and S13, it is determined whether or not to carry out the simulated engine restart drive by the ISG22 this time. Specifically, in S12, the elapsed time from the determination that the automatic stop of the engine 10 is permitted in the previous simulated engine restart drive is acquired. In S13, it is determined whether the elapsed time acquired in S12 is longer than a predetermined time. If it is determined in S13 that the elapsed time is longer than the predetermined time (S13: Yes), a simulated restart operation is performed, and the process proceeds to S14. On the other hand, if it is determined in S13 that the elapsed time is less than the predetermined time (S13: No), the process ends. As a result, it is possible to prevent the simulated restart operation from being repeatedly performed in a short period of time. Note that S12 corresponds to the “acquisition unit”.

In S14, the lockup clutch 13 is switched to the disengaged state to stop the rotation of the engine 10. If the lockup clutch 13 is disengaged while the vehicle is running and the fuel of the engine 10 is being cut, the rotation of the engine 10 is stopped while the vehicle is running. S14 corresponds to the "clutch control unit".

In S15, it is determined whether the engine speed has become 0, that is, whether the rotation of the engine 10 has stopped. When it is determined in S15 that the engine rotation speed is not 0 (S15: No), the determination in S15 is repeated until the rotation speed becomes 0. If it is determined in S15 that the engine speed is 0, the process proceeds to S16.

In S16, the engine 10 is restarted by the ISG22. With the rotation of the engine 10 stopped, the rotational force is applied to the engine 10 by driving the ISG 22. In S17, the voltage of the lithium ion storage battery 32 when the engine 10 is simulatedly restarted by the ISG 22 is acquired. Note that S16 corresponds to the "drive control unit".

In S18, it is determined whether the voltage of the lithium ion storage battery 32 when the ISG22 acquired in S17 is driven is larger than the threshold value Th1. The threshold value Th1 is the value of the voltage required for restarting the engine 10 by the ISG22. Note that S18 corresponds to the "determination unit".

When it is determined in S18 that the voltage of the lithium ion storage battery 32 is larger than the threshold value Th1 (S18: Yes), in S19, automatic stop is permitted and the process is terminated. When the automatic stop is permitted, engine control such as fuel cut control is performed until the automatic stop condition is satisfied.

When it is determined in S18 that the voltage of the lithium ion storage battery 32 is smaller than the threshold Th1 (S18: No), the lockup clutch 13 is connected in S20, and the fuel cut is released in S21. By connecting the lockup clutch 13, a rotational force is applied from the axle 17 to the crankshaft 11, and a rotational force capable of returning to self-reliance is applied to the engine 10. If the voltage required for restarting by the ISG22 is not secured and automatic stop is not permitted, the operating state of the engine 10 is restored to its own state by applying a rotational force from the axle 17 and releasing the fuel cut. , End the process. In addition, S20 and S21 correspond to "return control unit".

FIG. 4 is a time chart when automatic stop is permitted based on the voltage at the time of restart. The battery current indicates the charge / discharge current in the lithium ion storage battery 32, and the charge current is indicated by a positive value, while the discharge current is indicated by a negative value. The battery voltage indicates the output voltage of the lithium ion storage battery 32.

When the vehicle is decelerating and the vehicle speed has not reached a predetermined speed (at a time before the timing t11), the fuel cut control is executed. Before the timing t11, the engine rotation speed is held in a state higher than the fuel cut release rotation speed, and the lockup clutch 13 is connected. Further, since the regenerative power generation is performed by the ISG 22, the charging current is flowing into the lithium ion storage battery 32.

When the vehicle speed reaches a predetermined speed at the timing t11, the lockup clutch 13 is disengaged. When the lockup clutch 13 is disengaged, the engine speed decreases. Further, since the regenerative power generation by the ISG 22 is stopped, the charging current to the lithium ion storage battery 32 is stopped. Then, at the timing t12, the rotation of the engine 10 is stopped, and the engine rotation speed becomes 0.

After the engine speed becomes 0, the simulated engine 10 is restarted by the ISG 22 at the timing t13. During the simulated restart operation by the ISG 22, a discharge current equivalent to that at the time of actual restart flows from the lithium ion storage battery 32. The ISG22 is driven during the period from timing t13 to t14. Then, when the voltage of the lithium ion storage battery 32 is acquired during the period from timing t13 to t14, that is, the driving period of the ISG 22, and the voltage of the lithium ion storage battery 32 is larger than the threshold value Th1, automatic stop is permitted. Then, at the timing t15, when the vehicle speed becomes lower than the automatic engine stop speed and the automatic stop condition is satisfied, the engine 10 is automatically stopped.

When the restart condition is satisfied at the timing t16, the engine 10 is restarted by the ISG22. Then, the fuel injection is restarted at the timing t17, and the restart of the engine 10 is completed at the timing t18. When the restart of the engine 10 is completed, the lockup clutch 13 is engaged, and the vehicle is accelerated by operating the accelerator.

FIG. 5 is a time chart when automatic stop is not permitted based on the voltage at the time of restart. Since the timings t21 and t22 in FIG. 5 are the same as the timings t11 and t12 in FIG. 4, the description thereof will be omitted.

After the engine speed becomes 0, the simulated engine 10 is restarted by the ISG 22 at the timing t23. During the simulated restart operation by the ISG 22, a discharge current equivalent to that at the time of actual restart flows from the lithium ion storage battery 32. The ISG22 is driven during the period from timing t23 to t24. Then, when the voltage of the lithium ion storage battery 32 is acquired during the period from timing t23 to t24, that is, the driving period of the ISG 22, and the voltage of the lithium ion storage battery 32 is smaller than the threshold Th1, the automatic stop of the engine 10 remains unpermitted. Be made.

In this case, the lockup clutch 13 is connected at the timing t25. When the lockup clutch 13 is connected, a rotational force is applied from the axle 17 to the engine 10. Then, when the rotation speed at which the engine can return to self-sustaining is reached at the timing t26, the fuel injection is restarted by releasing the fuel cut, and the engine 10 is returned to self-sustaining. If the vehicle is running and the axle 17 is in a predetermined rotating state, the engine 10 can be returned to operation even if restarting by the ISG 22 is not permitted.

As described above, when the vehicle is running and before the automatic stop condition is satisfied, the voltage of the lithium ion storage battery 32 changes by applying the rotational force to the engine 10 by driving the ISG 22. In this case, a simulated restart operation by the ISG 22 is performed before the automatic stop of the engine 10 is actually performed. Specifically, if the lockup clutch 13 is shut off while the fuel of the engine 10 is cut while the vehicle is running, the rotation of the engine 10 is stopped while the vehicle is running. .. After the rotation of the engine 10 is stopped, a rotational force is applied to the engine 10 by driving the ISG 22 while the vehicle is running, that is, a simulated restart operation by the ISG 22 can be performed.

Then, it is possible to grasp whether or not the engine restart by the ISG 22 is properly performed from the voltage change of the lithium ion storage battery 32 at the time of the simulated restart by the ISG 22. That is, by performing a simulated restart operation by the ISG 22, it is possible to appropriately determine whether or not to allow the automatic stop of the engine 10 based on the voltage change of the lithium ion storage battery 32 at that time.

When the simulated restart operation by the ISG 22 is performed, for example, when the voltage of the lithium ion storage battery 32 becomes smaller than the threshold Th1 due to the driving of the ISG 22, the automatic stop of the engine 10 is not permitted. In such a case, it may be difficult to return the engine 10 to operation by driving the ISG 22. Even if it is difficult for the ISG 22 to return the engine 10 to operation, if the vehicle speed has reached a predetermined speed, that is, if the axle 17 is in a predetermined rotational state due to vehicle running, the rotational force from the axle 17 to the engine 10 The operation of the engine 10 can be returned by the addition. Therefore, when automatic stop is not permitted, the locked-up clutch 13 that has been shut off is connected, the rotational force from the axle 17 is applied, and the fuel cut is released, so that the operating state of the engine 10 becomes independent. It can be restored.

According to the present embodiment described in detail above, the following excellent effects can be obtained.

Since the configuration is such that whether or not the engine is automatically stopped is determined from the state when the ISG 22 is actually driven, the margin for determining whether or not the engine can be automatically stopped can be reduced, and the chances of performing idling stop can be increased. As a result, idling stop control can be properly performed.

When the vehicle is decelerating, the rotational force is applied to the engine 10 by driving the ISG22 based on the fact that the speed of the vehicle reaches a predetermined speed higher than the automatic engine stop speed included in the automatic stop condition. It was configured to be. As a result, even if it is difficult to return the engine 10 to the operation by driving the ISG 22, the operation of the engine 10 can be returned by applying the rotational force from the axle 17.

By shutting off the lockup clutch 13 during the fuel cut, after the rotation of the engine 10 is stopped, the rotational force is applied to the engine 10 by driving the ISG22 while the vehicle is running, that is, a simulated re-operation by the ISG22. The starting operation can be performed. Then, it is possible to properly determine whether or not to automatically stop the engine from the state when the ISG 22 is driven.

When it is determined that the automatic stop of the engine 10 is not permitted, the lockup clutch 13 is connected, the rotational force from the axle 17 is applied, and the fuel cut is released to change the operating state of the engine 10. It can be suitably returned to independence.

When the simulated restart operation by the ISG 22 is performed, power consumption due to the driving of the ISG 22 occurs. Therefore, it is not desirable that the simulated restart operation by the ISG 22 is excessively performed. In this regard, the lithium ion storage battery 32 is configured to apply the rotational force to the engine 10 by driving the ISG22 based on the information of the elapsed time from the previous determination that the automatic stop of the engine 10 is permitted. Excessive power consumption can be suppressed while properly monitoring the state of.

<Other embodiments>
The present invention is not limited to the above embodiment, and may be implemented as follows, for example. In the following, the parts that are the same or equal to each other in each embodiment are designated by the same reference numerals, and the description thereof will be incorporated for the parts having the same reference numerals.

-Instead of acquiring the elapsed time in S12 of FIG. 3, or in addition to the elapsed time, information such as the vehicle mileage and the battery power balance may be acquired. The battery power balance is calculated by the BMU 35 based on the power discharged from the lithium ion storage battery 32 and the power charged. Then, in S13, it is preferable to apply the rotational force to the engine 10 by driving the ISG 22 based on at least one of the information of the elapsed time, the vehicle mileage, and the battery power balance. Specifically, when the mileage of the vehicle is larger than a predetermined value, it is preferable to apply the rotational force to the engine 10 by driving the ISG 22. Further, when the discharge amount of the battery power balance from the previous determination is larger than a predetermined value, it is preferable to apply the rotational force to the engine 10 by driving the ISG 22.

-Instead of the voltage change of the lithium ion storage battery 32 at the time of restart, it may be determined whether or not automatic stop is permitted based on the change of the engine rotation speed. Specifically, in S17 of FIG. 3, instead of acquiring the voltage, the engine speed is acquired. Then, in S18, it is determined whether the engine rotation speed is larger than the threshold value Th2. The threshold value Th2 is a lower limit value of the rotation speed at which the engine 10 can return to self-reliance or a value larger than the lower limit value, and is, for example, 200 rpm.

A case of determining whether or not to allow automatic stop based on the engine speed will be described. FIG. 6 is a time chart when automatic stop is permitted based on the engine speed at the time of restart. Since each timing of FIG. 6 is the same as that of FIG. 4, the description of the same timing will be omitted.

The engine speed is acquired during the period from timing t13 to t14, that is, the driving period of ISG22. When the engine speed exceeds the threshold value Th2 for a predetermined time in the period of timings t13 to t14, automatic stop is permitted. Then, at the timing t15, when the vehicle speed becomes lower than the automatic engine stop speed and the automatic stop condition is satisfied, the engine 10 is automatically stopped.

Further, when the voltage of the lithium ion storage battery 32 is low and the power supplied to the ISG 22 is insufficient and the engine rotation speed is smaller than the threshold Th2, the automatic stop of the engine 10 is not permitted as in FIG. , The lockup clutch 13 is connected, the fuel cut is released, and the engine 10 is returned to the self-sustaining state.

-As a process for performing a simulated restart operation by ISG, ISG drive (torque assist of ISG 22) is performed by extension control to extend the fuel cut, and based on the voltage of the lithium ion storage battery 32 at that time. , It may be configured to determine whether to allow automatic stop.

FIG. 7 is a flowchart for determining whether to allow automatic stop control during extension control. The processing of this flowchart is executed by the ECU 40 at a predetermined cycle. During the fuel cut control at different timings, the automatic stop permission determination according to the flowchart of FIG. 3 and the automatic stop permission determination according to the flowchart of FIG. 7 may be executed. For example, when the process is completed in S13 of FIG. 3 (S13: No), the determination according to this flowchart may be performed.

In S31, it is determined whether the extension control is in progress. It is determined whether torque assist by ISG22 is performed in the fuel cut state. If it is determined that the extension control is not in progress (S31: No), the process ends. If it is determined that the extension control is in progress (S31: Yes), the process proceeds to S32. The control (extension control) for performing torque assist corresponds to the "drive control unit". Further, the extension control is a control in which the engine 10 is simulatedly restarted by the ISG 22.

In S32, the current (load current) discharged from the lithium ion storage battery 32 during the extension control is acquired. The load current to be acquired may be the value of the maximum discharge current in the determination period or the average value in the determination period. In S33, the voltage of the lithium ion storage battery 32 when the extension control is being performed is acquired. The voltage to be acquired may be the minimum voltage of the determination period or the average value of the determination period. The order in which S32 and S33 are carried out may be reversed. Further, the determination period is preferably a predetermined period after the extension control is started, for example, a period for driving the ISG 22 at the time of starting and a period for maintaining a rotation speed capable of returning to self-reliance. ..

In S34, it is determined whether the load current acquired in S32 is smaller than the current (starting current) when the engine 10 is started by the ISG22. The starting current flowing into the ISG 22 is controlled to a constant value. It is determined whether it is smaller than this starting current.

When it is determined in S34 that the load current is smaller than the starting current (S34: Yes), in S35, the voltage acquired in S33 is corrected. Specifically, based on a conversion formula calculated in advance, the ratio of the load current to the starting current is converted into a voltage value when the starting current is passed. In addition, when it is used together with the determination by the flowchart of FIG. 3, when it is determined that the load current is smaller than the starting current (S34: Yes), the process may be terminated.

In S34, when it is determined that the load current is not smaller than the starting current (S34: No), and after voltage correction is performed in S35, in S36, it is determined whether the voltage is larger than the threshold value Th3. The voltage used in S36 is the voltage acquired in S33 when it is determined in S34 that the load current is not smaller than the starting current, and in S34 it is determined that the load current is smaller than the starting current. If so, it is the voltage corrected in S35. The threshold value Th3 is a value of the voltage required for restarting the engine 10 by the ISG22, and may be the same as the threshold value Th1. In addition, S36 corresponds to a "determination unit".

When it is determined in S36 that the voltage is larger than the threshold value Th3 (S36: Yes), in S37, automatic stop is permitted and the process is terminated. When the automatic stop is permitted, the normal engine control is performed until the automatic stop condition is satisfied.

When it is determined in S36 that the voltage is smaller than the threshold value Th3 (S36: No), the fuel cut is released in S38. During the extension control, the ISG 22 applies a rotational force to the engine 10. Further, a rotational force is applied from the axle 17 to the crankshaft 11, and a rotational force capable of returning to self-reliance is applied to the engine 10. If the voltage required for restarting by the ISG22 is not secured and automatic stop is not permitted, the operating state of the engine 10 is restored to its own state by applying a rotational force from the axle 17 and releasing the fuel cut. , End the process. Note that S38 corresponds to the "return control unit".

FIG. 8 is a time chart when automatic stop is permitted based on the voltage during extension control. The battery current indicates the charge / discharge current in the lithium ion storage battery 32, and the charge current is indicated by a positive value, while the discharge current is indicated by a negative value. The battery voltage indicates the output voltage of the lithium ion storage battery 32.

The fuel cut control is executed in the state where the vehicle is decelerating and before the extension control is executed (at the time before the timing t31). Before the timing t31, the engine rotation speed is maintained in a state higher than the fuel cut release rotation speed.

At the timing t31, when the engine speed decreases and the extension condition is satisfied, torque assist (output assist) by ISG22 is performed. During the simulated restart operation by the ISG 22, a discharge current flows from the lithium ion storage battery 32. Then, the voltage and load current of the lithium ion storage battery 32 during the determination period of the timings t31 to t32 are acquired. When the load current is equal to or higher than the starting current and the voltage of the lithium ion storage battery 32 is larger than the threshold value Th3, automatic stop is permitted. Then, normal engine control (fuel cut control and extension control associated with deceleration) is continuously implemented. At the timing t33, when the vehicle speed becomes lower than the automatic engine stop speed and the automatic stop condition is satisfied, the engine 10 is automatically stopped and the extension control by the ISG 22 is stopped. Then, the lockup clutch 13 is disengaged.

When the restart condition is satisfied at the timing t34, the engine 10 is restarted by the ISG22. Then, the fuel injection is restarted at the timing t35, and the restart of the engine 10 by the ISG 22 is completed. When the restart of the engine 10 is completed, the lockup clutch 13 is engaged, and the vehicle is accelerated by operating the accelerator.

FIG. 9 is a time chart when automatic stop is not permitted based on the voltage during extension control. Since the timing t41 or earlier is the same as the timing t31 or earlier in FIG. 8, the description thereof will be omitted.

At the timing t41, when the engine speed decreases and the extension condition is satisfied, torque assist (output assist) by ISG22 is performed. During the simulated restart operation (torque assist) by the ISG 22, a discharge current flows from the lithium ion storage battery 32. Then, the voltage and load current of the lithium ion storage battery 32 during the determination period of the timings t41 to t42 are acquired.

If the voltage of the lithium ion storage battery 32 is smaller than the threshold value Th3 during the determination period, the automatic stop of the engine 10 is not permitted. At this time, the engine 10 is rotating at a predetermined rotation speed due to the torque assist (output assist) by the ISG 22 and the rotation of the axle 17. Then, at the timing t43, the fuel injection is restarted by releasing the fuel cut, and the engine 10 is returned to the self-sustaining state. If the vehicle is running and the engine 10 is in a predetermined rotating state, the engine 10 can be returned to operation even if restarting by the ISG 22 is not permitted.

-In the above embodiment, the lithium ion storage battery 32 supplies electric power to the ISG 22 when the engine is restarted, but this may be changed to supply electric power from the lead storage battery 31 to the ISG 22 when the engine is restarted. In this case, when the simulated restart drive of the ISG 22 is performed, it is preferable to determine whether to allow automatic stop based on the voltage of the lead storage battery 31.

-In the above embodiment, the lithium ion storage battery 32 and the lead storage battery 31 are connected to the ISG 22, but only one of them may be connected. Further, another high-density storage battery, for example, a nickel-hydrogen battery may be used.

The control unit (ECU 40) and its method described in the present disclosure are dedicated provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. It may be realized by a computer. Alternatively, the controls and methods thereof described in the present disclosure may be implemented by a dedicated computer provided by configuring the processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and method thereof described in the present disclosure may be a combination of a processor and memory programmed to perform one or more functions and a processor composed of one or more hardware logic circuits. It may be realized by one or more dedicated computers configured. Further, the computer program may be stored in a computer-readable non-transitional tangible recording medium as an instruction executed by the computer.

10 ... engine, 22 ... ISG, 32 ... lithium ion storage battery, 40 ... ECU.

Claims (7)

It is applied to a vehicle including an engine (10), a battery (31, 32), and a starting device (22, 24) driven by power supply from the battery to start the engine, and a predetermined automatic stop condition is satisfied. An idling stop control device (40) that automatically stops the engine and performs idling stop control for restarting the engine by the starting device when a predetermined restart condition is satisfied after the automatic stop.
When the vehicle is running and before the automatic stop condition is satisfied, the drive control unit that drives the starting device under a state in which the starting device can apply a rotational force to the engine.
A determination unit that determines whether or not to allow automatic stop of the engine based on a change in the voltage of the battery or a change in the engine rotation speed when the starter is driven by the drive control unit.
Idling stop control device equipped with. The drive control unit is driven by the starting device based on the fact that the speed of the vehicle reaches a predetermined speed higher than the vehicle speed condition included in the automatic stop condition when the vehicle is decelerated. The idling stop control device according to claim 1, wherein a rotational force is applied to the engine. The vehicle comprises a clutch (13) that connects or disconnects a power transmission path between the engine and an axle (17) that rotates with the wheels (18).
It is provided with a clutch control unit that shuts off the clutch when the fuel of the engine is cut while the vehicle is running.
Claim 1 or 2 that the drive control unit applies a rotational force to the engine by driving the starting device after the clutch is engaged by the clutch control unit and the rotation of the engine is stopped. The idling stop control device described in. When the determination unit determines that the automatic stop of the engine is not permitted, the clutch is engaged, and the operating state of the engine is returned to the self-sustaining state by applying a rotational force from the axle and releasing the fuel cut. The idling stop control device according to claim 3, further comprising a return control unit for causing the clutch to operate. The starting device is a rotary electric machine (22) that enables torque assist of the engine by power running drive.
The drive control unit applies a rotational force to the engine by driving the starting device as a torque assist in a state where the fuel of the engine is cut while the vehicle is running.
The determination unit according to claim 1 or 2, wherein the determination unit determines whether or not to allow automatic stop of the engine based on a change in the voltage of the battery or a change in the engine rotation speed when the torque assist is performed. Idling stop control device. A claim that includes a return control unit that returns the operating state of the engine to its own state by applying a rotational force from the axle and releasing the fuel cut when the determination unit determines that the automatic stop of the engine is not permitted. 5. The idling stop control device according to 5. The determination unit includes an acquisition unit that acquires at least one of information on the elapsed time from the previous determination, the vehicle mileage, and the battery power balance, which is determined to allow the automatic stop of the engine.
The drive control unit applies a rotational force to the engine by driving the starting device based on the information acquired by the acquisition unit when the vehicle is running and before the automatic stop condition is satisfied. The idling stop control device according to any one of claims 1 to 6.

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