JP7505298B2 - Vehicle control device - Google Patents

Description

The present invention relates to a vehicle control device.

Patent document 1 describes the inclusion of a battery output reduction determination unit that determines a reduction in battery output based on the battery voltage when the vehicle is first started, and an idle stop prohibition unit that prohibits idle stop when it is determined that the battery output is decreasing. It also describes the inclusion of a prohibition release unit that releases the prohibition of idle stop when the battery charge reaches or exceeds a prohibition release determination value that is preset as the charge amount that can generate the output required to restart the internal combustion engine.

JP 2012-246867 A

However, when the battery deteriorates and its actual capacity decreases, even a small amount of discharge from a fully charged state can significantly reduce engine starting performance, and there is a risk of the engine failing to restart from an idle stop state.

The present invention aims to provide a vehicle control device that can suppress engine restart problems caused by a decrease in the battery's starting performance.

In order to solve the above problems, the present invention provides a control device for a vehicle having an idle stop control unit that executes an idle stop for stopping an engine that generates driving force for running a vehicle when a preset stop condition is satisfied and that restarts the engine after the idle stop when a preset restart condition is satisfied, a battery that supplies power to a starter that starts the engine when the engine is restarted after being stopped, and a generator that generates power using power of the engine and charges the battery, the control device including an idle stop prohibition unit that prohibits the idle stop when a start-time minimum voltage, which is the lowest voltage of the battery when the engine is started, falls below an idle stop prohibition determination threshold, an idle stop prohibition release unit that releases the prohibition of the idle stop when it is determined that the battery has been charged and become fully charged after the idle stop has been prohibited by the idle stop prohibition unit, and a discharge amount control unit that controls the discharge amount of the battery so as to approach a predetermined target discharge amount. the target battery discharge amount setting unit is configured to subtract a first predetermined value from a previous value of the target discharge amount to set the target discharge amount when the minimum voltage at start-up falls below a first discharge amount limit judgment threshold that is a voltage higher than the idle stop prohibition judgment threshold, and to set the target discharge amount to the discharge side when the minimum voltage at start-up exceeds a second discharge amount limit judgment threshold that is a voltage higher than the first discharge amount limit judgment threshold, wherein the target battery discharge amount setting unit is configured to subtract a first predetermined value from a previous value of the target discharge amount to set the target discharge amount when the minimum voltage at start-up falls below the first discharge amount limit judgment threshold, and to add a second predetermined value to the previous value of the target discharge amount to set the target discharge amount when the minimum voltage at start-up exceeds the second discharge amount limit judgment threshold, calculate the target discharge amount every time the engine is restarted, and to set the target discharge amount to an initial state that is a value between a fully charged level and an upper discharge amount when the minimum voltage at start-up exceeds the second discharge amount limit judgment threshold and

In this way, the present invention can prevent engine restart problems caused by a decrease in the battery's starting performance.

FIG. 1 is a schematic diagram of a vehicle control device according to an embodiment of the present invention. FIG. 2 is a diagram showing an image of voltage behavior at engine start-up in a vehicle control device according to an embodiment of the present invention. FIG. 3 is a diagram showing an example of changes in the first discharge amount limit determination threshold and the second discharge amount limit determination threshold according to the engine coolant temperature in the vehicle control device according to the embodiment of the present invention. FIG. 4 is a flowchart showing a procedure for setting a target discharge amount in the control device for a vehicle according to an embodiment of the present invention. FIG. 5 is a flowchart showing a procedure of a target discharge amount calculation process of the control device for a vehicle according to one embodiment of the present invention. FIG. 6 is a time chart showing changes in the target discharge amount and the battery discharge amount due to the target discharge amount setting process of the vehicle control device according to one embodiment of the present invention.

A vehicle control device according to one embodiment of the present invention is a vehicle control device having an idle stop control unit that executes an idle stop to stop an engine that generates driving force for running the vehicle when a preset stop condition is satisfied, and restarts the engine after the idle stop when a preset restart condition is satisfied, a battery that supplies power to a starter that starts the engine when the engine is restarted after being stopped, and a generator that generates power using the engine power to charge the battery, and prohibits the idle stop when a minimum start voltage, which is the minimum voltage of the battery when the engine is started, falls below an idle stop prohibition judgment threshold. The system is configured to include an idle stop prohibition unit that prohibits the battery from being stopped, an idle stop prohibition release unit that releases the prohibition of the idle stop when it is determined that the battery has been charged and become fully charged after the idle stop prohibition unit has prohibited the idle stop, a discharge amount control unit that controls the discharge amount of the battery to approach a predetermined target discharge amount, and a target battery discharge amount setting unit that sets the target discharge amount to the charging side when the minimum voltage at start-up falls below a first discharge amount limiting judgment threshold that is a voltage higher than the idle stop prohibition judgment threshold, and sets the target discharge amount to the discharging side when the minimum voltage at start-up exceeds a second discharge amount limiting judgment threshold that is a voltage higher than the first discharge amount limiting judgment threshold.

As a result, the vehicle control device according to one embodiment of the present invention can suppress engine restart problems caused by a decrease in the battery's starting performance.

The vehicle control device according to the embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, a vehicle 1 equipped with a vehicle control device according to one embodiment of the present invention includes an engine 2, a starter 3, a battery 4, a generator 5, and a control device 6.

Engine 2 has multiple cylinders. In this embodiment, engine 2 is configured to perform a series of four strokes for each cylinder, consisting of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke.

The starter 3 is connected to the engine 2. The starter 3 is connected to the crankshaft of the engine 2 via a belt (not shown). When power is supplied to the starter 3, it rotates, causing the crankshaft to rotate and providing the rotational force to the engine 2 when it is started.

The battery 4 is, for example, a lead battery. The battery 4 supplies power to electrical loads of the vehicle 1, such as the starter 3 and the control device 6. The battery 4 is provided with a battery current sensor 12 that is attached to, for example, a connector on the negative side of the battery 4, detects the current of the battery 4, and outputs the detected value to the control device 6.
The generator 5 uses the power of the engine 2 to generate electricity and charge the battery 4 .

The control device 6 is composed of a computer unit equipped with a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), flash memory, input ports, and output ports.

The ROM of this computer unit stores various control constants, various maps, and the like, as well as a program for causing the computer unit to function as the control device 6. In other words, the computer unit functions as the control device 6 when the CPU executes the program stored in the ROM.

In addition to the battery current sensor 12 described above, various sensors such as an engine water temperature sensor 11 are connected to the input port of the control device 6 .
The engine water temperature sensor 11 detects the temperature of the engine coolant.

The control device 6 is configured to be able to communicate with an engine control device (not shown). The control device 6 receives a starter drive signal from the engine control device, which notifies the engine control device that the starter 3 has been driven. The control device 6 transmits an idle stop request that requests the engine 2 to be stopped and a restart request that requests the engine 2 to be restarted to the engine control device.

The control device 6 functions as an idle stop control unit 61 that controls an idle stop that stops the engine 2 when a preset stop condition is met, and then restarts the engine 2 when a preset restart condition is met.

The stopping conditions are, for example, that the vehicle speed is equal to or lower than a predetermined vehicle speed, the brake pedal is depressed, and the charge level of the battery 4 is equal to or higher than a predetermined value.

The restart conditions may be, for example, that the shift position is appropriate for starting, that the brake pedal is not being depressed, or any combination of these conditions is met.

The control device 6 functions as a battery voltage detection unit 62 that detects the voltage of the battery 4.

The control device 6 functions as an idle stop prohibition unit 63 that prohibits the idle stop control unit 61 from stopping the engine 2 (hereinafter referred to as "idle stop") when the minimum voltage Vmin at start-up, which is the minimum voltage of the battery 4 when the engine 2 is started, falls below the idle stop prohibition determination threshold V2. When idle stop is prohibited, the control device 6 controls the battery 4 to be charged.

The control device 6 has a function as an idle stop prohibition release unit 64 that releases the prohibition of idle stop when it is determined that the battery 4 has been charged and is fully charged after idle stop has been prohibited by the idle stop prohibition unit 63.

The control device 6 functions as a target battery discharge amount setting unit 65 that sets a target discharge amount according to the state of the battery 4. The control device 6 functions as a discharge amount control unit 66 that controls the discharge amount of the battery 4 so that it approaches the target discharge amount.

When the minimum voltage Vmin at startup falls below the first discharge amount limit judgment threshold V1a, the control device 6 sets the target discharge amount to the charge side (to reduce discharge). When the minimum voltage Vmin at startup exceeds the second discharge amount limit judgment threshold V1b, the control device 6 sets the target discharge amount to the discharge side (to increase discharge).

The first discharge amount limit judgment threshold V1a and the second discharge amount limit judgment threshold V1b are set to a voltage higher than the idle stop prohibition judgment threshold V2. The second discharge amount limit judgment threshold V1b is set to a voltage higher than the first discharge amount limit judgment threshold V1a.

When the engine 2 is started, the voltage of the battery 4 drops as shown in Figure 2. Depending on the minimum voltage at this time, Vmin, which is the minimum voltage at start-up, idle stop may be prohibited or the target discharge amount of the battery 4 may be changed.

The first discharge amount limiting judgment threshold V1a and the second discharge amount limiting judgment threshold V1b may be changed in value according to the temperature of the cooling water of the engine 2. As shown in FIG. 3, the first discharge amount limiting judgment threshold V1a and the second discharge amount limiting judgment threshold V1b should be set to higher voltages as the temperature of the cooling water of the engine 2 increases.

For example, when the minimum voltage Vmin at startup falls below the first discharge amount limit judgment threshold V1a, the control device 6 subtracts a first predetermined value A from the previous value of the target discharge amount.

For example, when the minimum voltage Vmin at startup exceeds the second discharge amount limit judgment threshold V1b, the control device 6 adds a second predetermined value B to the previous value of the target discharge amount.

The previous value of the target discharge amount is the target discharge amount calculated in the previous calculation of the target discharge amount, and is the current target discharge amount.

The first predetermined value A and the second predetermined value B may be the same value or may be different values. The first predetermined value A and the second predetermined value B are set according to the characteristics of the battery 4.

For example, when the discharge amount of the battery 4 becomes equal to the third predetermined value C, the control device 6 determines that the battery 4 has reached a fully charged level.

For example, when the discharge amount of the battery 4 is on the discharge side of the fourth predetermined value D and the minimum voltage at startup Vmin exceeds the second discharge amount limit judgment threshold V1b, the control device 6 sets the target discharge amount to the initial state and sets the discharge amount of the battery 4 to a range from the fully charged level to the upper discharge amount. The fourth predetermined value D is a value close to the upper discharge amount, for example, upper discharge amount - B < D < upper discharge amount. The upper discharge amount is the upper limit of the discharge amount of the battery 4.

When the target discharge amount is in the initial state, for example, the control device 6 sets the target discharge amount to a fifth predetermined value E. The fifth predetermined value E is a value between the full charge level and the upper discharge amount, and is calculated based on the state of the battery 4.

The target discharge amount setting process performed by the vehicle control device according to this embodiment, which is configured as described above, will be described with reference to Figures 4 and 5. The target discharge amount setting process described below is started when it is determined that the engine 2 has started and is in a complete explosion state.

In step S1, the control device 6 determines whether the minimum voltage Vmin at start-up has fallen below the idle stop prohibition determination threshold V2.

If it is determined that the minimum voltage Vmin at start-up is below the idle stop prohibition threshold V2, the control device 6 executes the process of step S2. If it is determined that the minimum voltage Vmin at start-up is not below the idle stop prohibition threshold V2, the control device 6 executes the process of step S4.

In step S2, the control device 6 determines that IS is prohibited/fully charged. After executing the process of step S2, the control device 6 executes the process of step S3.

In step S3, the control device 6 determines that the discharge limit level is increased. After executing the process of step S3, the control device 6 executes the process of step S8.

In step S4, the control device 6 determines whether the minimum voltage Vmin at startup has fallen below the first discharge limit determination threshold V1a.

If it is determined that the minimum voltage Vmin at start-up is below the first discharge limit determination threshold V1a, the control device 6 executes the process of step S5. If it is determined that the minimum voltage Vmin at start-up is not below the first discharge limit determination threshold V1a, the control device 6 executes the process of step S6.

In step S5, the control device 6 determines that the discharge limit level is increased. After executing the process of step S5, the control device 6 executes the process of step S8.

In step S6, the control device 6 determines whether the minimum voltage Vmin at startup exceeds the second discharge amount limit determination threshold V1b.

If it is determined that the minimum voltage Vmin at start-up exceeds the second discharge amount limit determination threshold V1b, the control device 6 executes the process of step S7. If it is determined that the minimum voltage Vmin at start-up does not exceed the second discharge amount limit determination threshold V1b, the control device 6 executes the process of step S8.

In step S7, the control device 6 determines that the discharge limit level is DOWN. After executing the process of step S7, the control device 6 executes the process of step S8.

In step S8, the control device 6 executes the target discharge amount calculation process shown in FIG. 5. After executing the process of step S8, the control device 6 ends the target discharge amount setting process.

The target discharge amount calculation process in step S8 of FIG. 4 will be explained with reference to FIG. 5.

In step S21, the control device 6 determines whether the battery 4 has reached a full charge level and is fully charged.

If it is determined that the battery is fully charged, the control device 6 executes the process of step S22. If it is determined that the battery is not fully charged, the control device 6 executes the process of step S24.

In step S22, the control device 6 cancels the IS prohibition/full charge determination. After executing the process of step S22, the control device 6 executes the process of step S23.

In step S23, the control device 6 sets the target discharge amount to the third predetermined value C. After executing the process of step S23, the control device 6 ends the target discharge amount setting process.

In step S24, the control device 6 determines whether the discharge limit level UP determination is satisfied.

If it is determined that the discharge limit level UP judgment is satisfied, the control device 6 executes the process of step S25. If it is determined that the discharge limit level UP judgment is not satisfied, the control device 6 executes the process of step S26.

In step S25, the control device 6 sets the target discharge amount to the previous value minus the first predetermined value A. After executing the process of step S25, the control device 6 ends the target discharge amount calculation process.

In step S26, the control device 6 determines whether the discharge limit level DOWN determination is true or not.

If it is determined that the discharge limit level DOWN judgment is satisfied, the control device 6 executes the process of step S27. If it is determined that the discharge limit level DOWN judgment is not satisfied, the control device 6 executes the process of step S30.

In step S27, the control device 6 determines whether the discharge amount of the battery 4 is greater than a fourth predetermined value D.

If it is determined that the discharge amount of the battery 4 is greater than the fourth predetermined value D, the control device 6 executes the process of step S29. If it is determined that the discharge amount of the battery 4 is not greater than the fourth predetermined value D, the control device 6 executes the process of step S28.

In step S28, the control device 6 sets the target discharge amount to the previous value plus the second predetermined value B. After executing the process of step S28, the control device 6 ends the target discharge amount calculation process.

In step S29, the control device 6 sets the target discharge amount to a fifth predetermined value E. After executing the process of step S29, the control device 6 ends the target discharge amount calculation process.

In step S30, the control device 6 sets the target discharge amount to the previous value. After executing the process of step S30, the control device 6 ends the target discharge amount calculation process.

Such target discharge amount setting processing will be described with reference to FIG.
At time t1, the engine 2 is started, and the minimum voltage Vmin at start-up exceeds the second discharge amount limit determination threshold V1b, so that the discharge limit level DOWN determination is established and the target discharge amount is set to the previous value + the second predetermined value B.

At time t2, the engine 2 is started, and the minimum voltage Vmin at start-up is below the first discharge amount limit judgment threshold V1a, so the discharge limit level UP judgment is satisfied and the target discharge amount is set to the previous value - the first predetermined value A.

At time t3, the engine 2 is started, and the minimum voltage Vmin at start-up is below the idle stop prohibition threshold V2, so the IS prohibition/full charge judgment is established and the battery 4 is charged. In addition, the discharge limit level UP judgment is established, and the target discharge amount is set to the previous value - the first predetermined value A.

At time t4, when the discharge amount of battery 4 becomes equal to the third predetermined value C, it is determined that battery 4 has reached the full charge level, the battery is fully charged, the IS prohibition/full charge determination is released, and the target discharge amount is set to the third predetermined value C.

At time t5, the engine 2 is started, and the minimum voltage Vmin at start-up exceeds the second discharge amount limit judgment threshold V1b, so the discharge limit level DOWN judgment is established and the target discharge amount is set to the previous value + the second predetermined value B.

At time t6, the engine 2 is started, and the minimum voltage Vmin at start-up exceeds the second discharge amount limit judgment threshold V1b, so the discharge limit level DOWN judgment is established and the target discharge amount is set to the previous value + the second predetermined value B.

At time t7, the engine 2 is started, and the minimum voltage Vmin at start-up exceeds the second discharge amount limit judgment threshold V1b, so the discharge limit level DOWN judgment is established and the target discharge amount is set to the previous value + the second predetermined value B.

This process is repeated until the target discharge amount becomes greater than the fourth predetermined value D at time t8.

At time t9, the engine 2 is started, the minimum voltage Vmin at start-up exceeds the second discharge amount limit judgment threshold V1b, and the discharge amount of the battery 4 exceeds the fourth predetermined value D, so the target discharge amount is set to the initial state and the fifth predetermined value E.

In this way, in this embodiment, the control device 6 sets the target discharge amount to the charging side when the minimum voltage at startup Vmin, which is the minimum voltage of the battery 4 when the engine 2 is started, falls below the first discharge amount limit judgment threshold V1a, and sets the target discharge amount to the discharging side when the minimum voltage at startup Vmin exceeds the second discharge amount limit judgment threshold V1b.

When the minimum voltage Vmin at startup falls below the first discharge limit determination threshold V1a, the target discharge amount is set to the charging side, thereby preventing engine restart problems caused by a decrease in the starting performance of the battery 4.

When the minimum voltage Vmin at startup falls below the first discharge limit judgment threshold V1a, the target discharge amount is set to the charging side, so the number of times that the minimum voltage Vmin at startup falls below the idle stop prohibition judgment threshold V2 can be reduced. This makes it possible to ensure the frequency of idle stop execution.

When the minimum voltage Vmin at startup exceeds the second discharge limit judgment threshold V1b, the target discharge amount is set to the discharge side, so the frequency of power generation can be reduced. This ensures the frequency of idle stop execution.

In addition, when the minimum voltage Vmin at start-up falls below the first discharge amount limit judgment threshold V1a, the control device 6 subtracts a first predetermined value A from the previous value of the target discharge amount, and when the minimum voltage Vmin at start-up exceeds the second discharge amount limit judgment threshold V1b, the control device 6 adds a second predetermined value B to the previous value of the target discharge amount, thereby calculating the target discharge amount each time the engine 2 is restarted.

This allows the discharge amount of battery 4 to be appropriately managed based on the target discharge amount. This makes it possible to prevent engine restart problems and ensure the frequency of idle stop execution.

In addition, when the discharge amount of the battery 4 is on the discharge side of a fourth predetermined value D near the upper discharge amount and the minimum voltage Vmin at startup exceeds the second discharge amount limit judgment threshold V1b, the control device 6 sets the target discharge amount to the initial state and sets the discharge amount of the battery 4 to the range from the fully charged level to the upper discharge amount.

This allows a wider range of target discharge amounts to be used, and the discharge amount of battery 4 can be managed over a wider range.

In addition, the control device 6 controls the battery 4 to be charged when idle stop is prohibited.

This allows the battery 4 to be fully charged quickly and the idle stop prohibition to be lifted early.

In this embodiment, the target discharge amount setting process is executed when the idle stop is restarted, but the target discharge amount setting process may also be executed when the engine 2 is started for the first time (every time the engine 2 is started).

In this embodiment, an example has been described in which the control device 6 performs various determinations and calculations based on various sensor information, but the present invention is not limited to this. The vehicle 1 may be provided with a communication unit capable of communicating with an external device such as an external server, and various determinations and calculations may be performed by the external device based on the detection information of the various sensors transmitted from the communication unit. The communication unit may receive the determination results and calculation results, and the received determination results and calculation results may be used to perform various controls.

Although an embodiment of the present invention has been disclosed, it is apparent that modifications may be made by one of ordinary skill in the art without departing from the scope of the present invention. All such modifications and equivalents are intended to be included in the following claims.

REFERENCE SIGNS LIST 1 vehicle 2 engine 3 starter 4 battery 5 generator 6 control device 11 engine water temperature sensor 12 battery current sensor 61 idling stop control unit 62 battery voltage detection unit 63 idling stop prohibition unit 64 idling stop prohibition release unit 65 target battery discharge amount setting unit 66 discharge amount control unit

Claims (2)

A control device for a vehicle having an idle stop control unit that executes an idle stop for stopping an engine that generates a driving force for running a vehicle when a preset stop condition is satisfied, and restarts the engine after the idle stop when a preset restart condition is satisfied, a battery that supplies power to a starter that starts the engine when the engine is restarted after being stopped, and a generator that generates power using power from the engine to charge the battery,
an idle stop prohibition unit that prohibits the idle stop when a minimum voltage at start-up, which is a minimum voltage of the battery when the engine is started, falls below an idle stop prohibition determination threshold;
an idle stop prohibition release unit that releases the prohibition of the idle stop when it is determined that the battery is fully charged after the idle stop is prohibited by the idle stop prohibition unit;
a discharge amount control unit that controls a discharge amount of the battery so as to approach a predetermined target discharge amount;
a target battery discharge amount setting unit that sets the target discharge amount to the charge side when the minimum voltage at start-up falls below a first discharge amount limiting judgment threshold that is a voltage higher than the idle stop prohibition judgment threshold, and sets the target discharge amount to the discharge side when the minimum voltage at start-up exceeds a second discharge amount limiting judgment threshold that is a voltage higher than the first discharge amount limiting judgment threshold ,
the target battery discharge amount setting unit, when the minimum voltage at startup falls below the first discharge amount limit determination threshold, subtracts a first predetermined value from a previous value of the target discharge amount to set the target discharge amount, and when the minimum voltage at startup exceeds the second discharge amount limit determination threshold, adds a second predetermined value to the previous value of the target discharge amount to set the target discharge amount, and calculates the target discharge amount every time the engine is restarted;
A vehicle control device that, when the minimum voltage at startup exceeds the second discharge amount limit determination threshold and the addition of the second specified value to the previous value of the target discharge amount exceeds the upper discharge amount of the battery, resets the target discharge amount to an initial state that is a value between the full charge level and the upper discharge amount . The vehicle control device according to claim 1 , wherein the idle stop prohibition unit controls the battery to be in a charged state when the idle stop is prohibited.

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