JP2017040218A - Internal combustion engine starter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve startability of an internal combustion engine.SOLUTION: A starter for an engine 2, provided with a motor generator 9 driven by electric power supplied from a driving battery 11 mounted in a vehicle 1 and starting the engine 2, is configured such that a starting-time fuel correction control unit 50 in an engine control unit 22 increases an injection amount of a fuel to the engine 2 at a time of starting the engine 2 when a state of health SOH of the driving battery 11 estimated by a hybrid control unit 20 falls to be equal to or lower than a threshold Sa.SELECTED DRAWING: Figure 1

Description

  The present invention relates to fuel injection control at the start of an internal combustion engine.

  2. Description of the Related Art Conventionally, for starting an internal combustion engine mounted on a vehicle, a rotating electrical machine such as a starter motor that is driven by being supplied with electric power from a battery (battery) mounted on the vehicle has been widely used. The rotating electrical machine requires a large current when starting the internal combustion engine. Therefore, for example, if the temperature of the internal combustion engine decreases and the internal combustion engine cannot be started immediately and the drive time of the rotating electrical machine is prolonged, the charging rate of the battery may be reduced and it may be difficult to start the internal combustion engine. .

  Therefore, Patent Document 1 discloses a technique for improving the startability of the internal combustion engine by increasing the fuel injection amount at the time of restart when the rotating electrical machine is driven and cannot be started.

JP 2012-236568 A

  However, as in Patent Document 1, even if the fuel injection amount is increased to improve the startability when starting is impossible, the electric power of the battery is reduced when the rotating electrical machine is driven and cannot be started. There is a possibility that the engine cannot be started even if the amount of fuel injection is increased even if the fuel injection amount is increased. In particular, when the capacity of the battery is low, or when the battery charge rate is low, such as an electric vehicle that shares the battery for driving the starter motor and the battery for traveling the vehicle. There is a risk that it may be difficult to start the internal combustion engine.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a starting device that improves the startability of an internal combustion engine in an internal combustion engine that is started by a rotating electrical machine. .

In order to achieve the above object, a starter for an internal combustion engine according to claim 1 of the present invention is an internal combustion engine including a rotating electrical machine that is driven by electric power supplied from a battery mounted on a vehicle to start the internal combustion engine. A deterioration rate detection unit for detecting a deterioration rate of the battery, the engine starter;
And a start-time fuel injection control unit that controls a fuel injection amount to the internal combustion engine when the internal combustion engine is started based on the deterioration rate.

Preferably, the start time fuel injection control unit determines the fuel injection amount to the internal combustion engine at the time of start when the deterioration rate is equal to or less than a predetermined threshold. It is better to increase than when it is higher than the threshold.
Preferably, the starting device further includes a battery temperature detecting unit that detects a temperature of the battery, and the starting fuel injection control unit is configured to control the internal combustion engine based on the temperature of the battery and the deterioration rate. The amount of fuel injected into the internal combustion engine at the time of starting may be controlled.

Preferably, the starting device further includes an engine temperature detecting unit that detects a temperature of the internal combustion engine, and the start time fuel injection control unit is configured to reduce a temperature of the internal combustion engine at the time of starting. Accordingly, the threshold value may be lowered.
Preferably, the start-time fuel injection control unit controls the fuel injection amount to the internal combustion engine at the time of starting the internal combustion engine continuously based on at least the deterioration rate. .

According to the present invention, since the fuel injection amount to the internal combustion engine at the start of the internal combustion engine is controlled based on the deterioration rate of the battery, it can be supplied to the rotating electrical machine that changes with the deterioration rate of the battery. The fuel injection amount can be controlled in accordance with the amount of electric power.
Even if the battery has a high charge rate, if the deterioration rate is low, the amount of power that can be supplied decreases. Therefore, by controlling the fuel injection amount based on the deterioration rate, a battery such as a rotating electrical machine for starting an internal combustion engine can be used. In addition, when the power consumption is large, it is possible to improve the startability by increasing the fuel injection amount before the charge rate is reduced by the start.

1 is a schematic configuration diagram of a plug-in hybrid vehicle according to an embodiment of the present invention. It is a block diagram of the engine and control system which concern on this embodiment. It is a flowchart which shows the fuel correction control point. It is a table for calculating a deterioration coefficient. It is a table for calculating the temperature coefficient. It is a graph which shows an example of the relationship between a deterioration rate, a charging rate, and the output of a battery.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a plug-in hybrid vehicle (hereinafter referred to as a vehicle 1) according to an embodiment of the present invention.
The vehicle 1 according to the present embodiment can travel by driving the front wheels 3 by the output of the engine 2 (internal combustion engine), and also an electric front motor 4 that drives the front wheels 3 and an electric rear motor that drives the rear wheels 5. 6 is a four-wheel drive vehicle.

The engine 2 can drive the drive shaft 8 of the front wheel 3 via the front transaxle 7 and can drive the motor generator 9 (rotary electric machine) via the front transaxle 7 to generate electric power. Yes. The engine 2 and the front wheel 3 are connected via a clutch 16 disposed in the front transaxle 7.
The front motor 4 is driven by being supplied with high-voltage power from a drive battery 11 (battery) mounted on the vehicle 1 and a motor generator 9 via the front control unit 10, and the front wheels are connected via the front transaxle 7. 3 drive shafts 8 are driven.

The rear motor 6 is driven by being supplied with high-voltage power from the driving battery 11 via the rear control unit 12, and drives the drive shaft 14 of the rear wheel 5 via the rear transaxle 13.
The electric power generated by the motor generator 9 can charge the driving battery 11 via the front control unit 10 and can supply electric power to the front motor 4 and the rear motor 6.

The motor generator 9 has a function as a starter motor that is driven by power supplied from the drive battery 11 and starts the engine 2.
The driving battery 11 is composed of a secondary battery such as a lithium ion battery, and has a battery module (not shown) in which a plurality of battery cells are combined. The drive battery 11 includes a charge rate detection unit 11 a that detects the charge rate SOC of the drive battery 11 and a battery temperature sensor 11 b (battery temperature detection unit) that detects the temperature of the drive battery 11. .

The front control unit 10 has a function of controlling the output of the front motor 4 and the power generation amount and output of the motor generator 9 based on a control signal from the hybrid control unit 20 mounted on the vehicle.
The rear control unit 12 has a function of controlling the output of the rear motor 6 based on a control signal from the hybrid control unit 20 (deterioration rate detection unit).

The engine control unit 22 is a control device for the engine 2 and includes an input / output device, a storage device (ROM, RAM, nonvolatile RAM, etc.), a central processing unit (CPU), a timer, and the like. The engine control unit 22 performs drive control of the engine 2 based on a control signal (request output) from the hybrid control unit 20.
The vehicle 1 is also provided with a fuel tank 17 that stores fuel for supplying fuel to the engine 2 and a charger (not shown) that charges the driving battery 11 with an external power source.

The hybrid control unit 20 is a control device for performing comprehensive control of the vehicle 1, and includes an input / output device, a storage device (ROM, RAM, nonvolatile RAM, etc.), a central processing unit (CPU), a timer, and the like. Consists of including.
A front control unit 10, a rear control unit 12, and an engine control unit 22 are connected to the input side of the hybrid control unit 20, and detection and operation information from these devices is input.

On the other hand, to the output side of the hybrid control unit 20, a front control unit 10, a rear control unit 12, an engine control unit 22, and a clutch 16 of the front transaxle 7 are connected.
The hybrid control unit 20 calculates a vehicle request output required for driving the vehicle 1 based on various detection amounts such as the accelerator operation information degree of the vehicle 1 and various operation information, and the engine control unit 22, front A control signal is transmitted to the control unit 10 and the rear control unit 12 to switch the running mode (EV mode, series mode, parallel mode), the outputs of the engine 2, the front motor 4 and the rear motor 6, the generated power of the motor generator 9, and Output and control of connection / disconnection of the clutch 16 in the front transaxle 7 is controlled.

In the EV mode, the engine 2 is stopped, and the front motor 4 and the rear motor 6 are driven by the electric power supplied from the driving battery 11 to run.
In the series mode, the clutch 16 of the front transaxle 7 is disconnected, and the motor generator 9 is operated by the engine 2. Then, the front motor 4 and the rear motor 6 are driven to run by the electric power generated by the motor generator 9 and the electric power supplied from the driving battery 11. In the series mode, the rotation speed of the engine 2 is set to an efficient value, and the power generated by the surplus output is supplied to the drive battery 11 to charge the drive battery 11.

  In the parallel mode, the clutch 16 of the front transaxle 7 is connected, and power is mechanically transmitted from the engine 2 via the front transaxle 7 to drive the front wheels 3. Further, the front motor 4 and the rear motor 6 are driven to run by the electric power generated by operating the motor generator 9 by the engine 2 and the electric power supplied from the driving battery 11.

  For example, the hybrid control unit 20 sets the traveling mode to the parallel mode in an efficient region of the engine 2 such as a high-speed region. Further, in the region excluding the parallel mode, that is, the middle / low speed region, the mode is switched between the EV mode and the series mode based on the charging rate SOC of the driving battery 11. Therefore, the hybrid control unit 20 outputs a start signal to the engine control unit 22 to start the engine 2 when switching from the EV mode to the series mode.

FIG. 2 is a configuration diagram of the engine 2 and the control system according to the present embodiment.
The engine 2 according to the present embodiment is, for example, a gasoline engine having a plurality of cylinders, and FIG. 2 shows one cylinder among the plurality of cylinders.
As shown in FIG. 2, on the input side of the engine control unit 22, an air flow sensor 42 that detects the intake air flow rate of the engine 2, a rotation speed sensor 43 that detects the actual rotation speed of the engine 2, and a cooling as the temperature of the engine 2. A water temperature sensor 44 (engine temperature detection unit) that detects an engine water temperature Tw that is the temperature of water and other various sensors are connected, and various detection signals are input. Further, the engine control unit 22 inputs from the hybrid control unit 20 the charging rate SOC of the driving battery 11, the battery deterioration rate SOH, the battery temperature Tb, the accelerator operation amount of the vehicle, the vehicle speed, and the travel mode.

On the other hand, a throttle valve 37, a fuel injection valve 45, an ignition device (ignition coil, ignition plug) 46, and the like are connected to the output side of the engine control unit 22.
The engine control unit 22 opens the throttle valve 37, the fuel injection amount by the fuel injection valve 45, and the fuel injection timing so that the target output torque of the engine 2 calculated based on various signals such as the accelerator operation amount can be obtained. The ignition timing by the ignition device 46 is controlled.

The engine control unit 22 further includes a start time fuel correction control unit 50 (start time fuel injection control unit) that performs correction control of the fuel injection amount at the time of engine start.
FIG. 3 is a flowchart showing a fuel injection amount correction control procedure when the engine is started according to this embodiment. FIG. 4 is a deterioration coefficient calculation table. FIG. 5 is a temperature coefficient calculation table.

The fuel injection amount correction control routine shown in FIG. 3 is performed when the engine is started.
As shown in FIG. 3, first, in step S <b> 10, the current battery deterioration rate SOH of the drive battery 11 is input from the hybrid control unit 20. The battery deterioration rate SOH is a known index that is the ratio of the current full charge capacity to the full charge capacity at the time of shipment. The battery deterioration rate SOH is sequentially calculated based on a change in the charging rate SOC of the driving battery 11 with respect to the input / output current of the driving battery 11 when the driving battery 11 is used, for example, and stored in the hybrid control unit 20. . Then, the process proceeds to step S20.

In step S20, a deterioration coefficient K1 is calculated based on the battery deterioration rate SOH input in step S10. The deterioration coefficient K1 is calculated from the battery deterioration rate SOH using, for example, a map as shown in FIG. As shown in FIG. 4, as the battery deterioration rate SOH increases, the deterioration coefficient K1 also increases. Then, the process proceeds to step S30.
In step S30, the battery temperature Tb is input from the battery temperature sensor 11b. Then, the process proceeds to step S40.

In step S40, a temperature coefficient K2 is calculated based on the battery temperature Tb. The temperature coefficient K2 is calculated using, for example, a map as shown in FIG. As shown in FIG. 5, the temperature coefficient K2 increases as the battery temperature Tb increases. Then, the process proceeds to step S50.
In step S50, the fuel injection amount at the start is corrected. The fuel injection amount at the start is calculated by adding the warm-up correction amount, the asynchronous injection amount, the injection amount immediately after the start, etc. to the basic fuel injection amount set based on the engine speed or the like. The warm-up correction amount is the fuel correction (increase) amount for stabilizing the engine operation during cold driving, the asynchronous injection amount is the fuel injection amount set without being related to the engine speed, and the injection amount immediately after starting is This is the fuel injection amount that is corrected to increase when the engine is started. Then, as shown in the following equation (1), when the battery deterioration rate SOH is equal to or less than the threshold value Sa, the deterioration calculated in step S20 for the warm-up correction amount, the asynchronous injection amount, and the injection amount immediately after start-up, respectively. The fuel injection amount is corrected by integrating the coefficient K1 and the temperature coefficient K2 calculated in step S20.

Fuel injection amount (at start-up) = basic fuel injection amount + warm-up correction amount × K1 × K2 + asynchronous injection amount × K1 × K2 + injection amount immediately after start × K1 × K2 (1)
Note that different maps may be prepared and set to different values for the deterioration coefficient K1 and the temperature coefficient K2 for each warm-up correction amount, asynchronous injection amount, and injection amount immediately after startup. Then, this routine ends.

The threshold value Sa used in step S50 will be described with reference to FIG.
FIG. 6 is a graph showing an example of the relationship between the battery deterioration rate SOH and the charge rate SOC and the maximum output Pmax of the drive battery 11.
For example, as shown in FIG. 6, the maximum output Pmax that can be output by the drive battery 11 becomes substantially constant when the charging rate SOC increases and becomes close to full charge (100%). However, even if the charge rate SOC of the drive battery 11 is close to full charge, the maximum output Pmax of the drive battery 11 decreases as the battery deterioration rate SOH decreases. When the battery deterioration rate SOH decreases to the threshold value Sa (about 60% or less in FIG. 6), the maximum output Pmax of the drive battery 11 is lower than the engine startable output Ps even when the charge rate SOC is fully charged. Thus, the engine 2 cannot be started. Such engine startable output Ps and threshold value Sa may be confirmed in advance and used for the calculation in step S50.

  The engine startable output Ps is an output of the drive battery 11 necessary for starting the engine 2 and changes depending on the engine temperature. Specifically, since the engine startable output Ps increases as the engine temperature decreases, the engine water temperature Tw is further input in step S50, and the engine startable output Ps increases as the engine water temperature Tw decreases, Along with this, the threshold value Sa may be changed.

According to the control as described above, in the present embodiment, the fuel injection amount at the start is corrected based on the battery deterioration rate SOH and the battery temperature Tb of the drive battery 11. Thereby, the fuel injection amount at the time of start-up is corrected according to the output possible from the drive battery 11, and the startability of the engine 2 can be improved.
Specifically, when the battery deterioration rate SOH is equal to or less than the threshold value Sa, the correction is performed so that the fuel injection amount at the time of starting increases as the battery deterioration rate SOH of the driving battery decreases. Can be secured.

Further, since the fuel injection amount at the start is further corrected based on the battery temperature Tb, it can be corrected so as to increase the fuel injection amount corresponding to a case where the output decreases with the change of the battery temperature Tb. The startability can be further improved.
Further, when correcting the fuel injection amount, the fuel injection amount is corrected so as to continuously change based on the battery deterioration rate SOH and the battery temperature Tb, so that the fuel injection amount can be suppressed to an appropriate amount while ensuring startability. It becomes possible.

In this way, startability can be ensured regardless of the battery deterioration of the drive battery 11, and the start-up time can be shortened to suppress a decrease in the charging rate of the drive battery 11.
Further, since the threshold value Sa of the battery deterioration rate SOH for correcting the fuel injection amount is changed based on the engine water temperature Tw, the fuel injection amount can be further suppressed to an appropriate amount while ensuring startability.

  In addition, although the method of correct | amending so that the fuel injection amount at the time of starting may be increased when the charging rate SOC of the drive battery 11 falls can be considered, it consumes large electric power like the motor generator 9 used for engine starting Then, there is a possibility that startability cannot be ensured even if the charge rate SOC of the drive battery 11 is close to full charge, so that the fuel injection at the start is based on the battery deterioration rate SOH as in this embodiment. By correcting the amount, startability can be further ensured.

This is the end of the description of the embodiment of the invention, but the invention is not limited to this embodiment.
For example, in the above embodiment, the correction of the fuel injection amount based on the battery deterioration rate SOH is continuously changed. However, the correction of the fuel injection amount may be performed in stages.
In the present embodiment, the fuel injection amount correction control is performed in the engine control unit 22, but may be performed in another control unit mounted on the vehicle 1 such as the hybrid control unit 20.

In the above embodiment, the fuel injection amount at the start is corrected based on the battery deterioration rate SOH, the battery temperature Tb, and the engine water temperature Tw. However, the present invention is based on at least the battery deterioration rate SOH. What is necessary is just to correct | amend the injection quantity.
In the present embodiment, the present invention is applied to a plug-in hybrid vehicle. However, the present invention can be widely applied to an internal combustion engine that is started by a rotating electrical machine that is driven by electric power supplied from a battery.

1 Vehicle 2 Engine (Internal combustion engine)
9 Motor generator (rotary electric machine)
11 Drive battery (battery)
11b Battery temperature sensor (battery temperature detector)
20 Hybrid control unit (deterioration rate detector)
22 Engine control unit 44 Water temperature sensor (Engine temperature detector)
50 Start-up fuel correction control unit (start-up fuel injection control unit)

Claims (5)

An internal combustion engine starter comprising a rotating electrical machine that is driven by electric power supplied from a battery mounted on a vehicle and starts the internal combustion engine,
A deterioration rate detector for detecting the deterioration rate of the battery;
An internal combustion engine starter comprising: a start-time fuel injection control unit that controls a fuel injection amount to the internal combustion engine when starting the internal combustion engine based on the deterioration rate.   When the deterioration rate is equal to or lower than a predetermined threshold, the start-time fuel injection control unit determines the amount of fuel injected into the internal combustion engine at the time of starting than when the deterioration rate is higher than a predetermined threshold. The starter for an internal combustion engine according to claim 1, wherein The starter further includes a battery temperature detection unit for detecting the temperature of the battery,
3. The fuel injection control unit at start-up controls fuel injection amount to the internal combustion engine at the time of start-up of the internal combustion engine based on the temperature of the battery and the deterioration rate. A starter for an internal combustion engine as described. The starter further includes an engine temperature detector that detects the temperature of the internal combustion engine,
4. The internal combustion engine starter according to claim 2, wherein the start-time fuel injection control unit decreases the threshold as the temperature of the internal combustion engine decreases during the start. 5. .   The fuel injection control unit at the start is controlled based on at least the deterioration rate so as to continuously change a fuel injection amount to the internal combustion engine at the time of starting the internal combustion engine. The starter for an internal combustion engine according to any one of 1 to 4.

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