JP2010270643A - Engine start controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine start controller capable of continuing starting of an engine even when a battery is in a low voltage state, and capable of improving startability of the engine. <P>SOLUTION: The engine start controller includes a microcomputer 40 for outputting a control signal for driving a starter, and a power source IC30 formed separately from the microcomputer 40 and maintaining a state of the control signal output from the microcomputer 40 when it is detected that the voltage supplied to the microcomputer 40 is equal to or less than a prescribed value in the state that the control signal for bringing the starter in the driving state is output from the microcomputer 40. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an engine start control device.

  The engine in the vehicle is usually started by operating an ignition switch using an ignition key. When the driver turns the ignition key from the ignition switch to the starter on position, the starter switch is turned on and an engine starter signal is input to a microcomputer provided in the engine control device. In response to the starter signal, the microcomputer performs output processing of a starter output (a control signal for driving the starter) that turns on the starter relay in order to supply power to the starter motor. When the starter relay is turned on, power is supplied from the battery to the starter motor, so that the starter motor is driven.

At this time, the starter motor requires a large starting current in order to start the engine by executing cranking from the engine stopped state. For this reason, the battery voltage temporarily decreases, and a low voltage state in which the battery voltage falls below a voltage at which the microcomputer can normally operate (hereinafter abbreviated as a reset voltage) may occur.
When the battery voltage falls below the reset voltage, the microcomputer is reset. When the microcomputer is reset, the microcomputer stops the starter output. Accordingly, the starter relay that was turned on by the starter output from the microcomputer is turned off. As a result, the starter motor cannot receive power from the battery and cannot start the engine.
Therefore, as shown in Patent Documents 1 to 5, a technology has been developed that can continue the engine start even if the microcomputer is reset.

In Patent Document 1, electric power is supplied from the battery to the starter motor from the time when the operation of the microcomputer is stopped until the start of the engine is completed using a normally closed relay. Note that the normally closed relay is a relay in which the switch is turned off when conducting. In Patent Document 1, the normally closed relay is turned on when the starter switch is in an on state and the microcomputer stops operating.
In Patent Document 2 and Patent Document 3, by providing a control device different from the engine control device, the starter relay is turned on using another control device when the microcomputer of the engine control device is reset.
In Patent Documents 4 and 5, the control performed by the microcomputer before resetting using a non-volatile memory is stored, and after returning from reset, the microcomputer reads the data in the non-volatile memory so that control before resetting is performed. continuing.

JP 2005-16388 A JP 2006-112243 A JP 2006-118481 PR JP 2007-320456 A JP 11-85333 A

  However, in Patent Document 1, in order for the pre-driving means to supply the battery power to the starter when the microcomputer is reset, the driver must keep the starter switch in the on state, and the engine startability There was a problem that did not improve. In Patent Documents 2 and 3, there is a problem that a control device different from the engine control device is required. Further, Patent Documents 4 and 5 have a problem that the start control cannot be continued while the microcomputer is reset.

The present invention has been made in view of the above circumstances, and its purpose is as follows:
An object of the present invention is to provide an engine start control device that can not only continue the engine start even when the battery is in a low voltage state but also improve the engine startability.

The invention according to claim 1 is an engine start control device that controls engine start by driving a starter, wherein the control unit that outputs a control signal for driving the starter is separate from the control unit. When the control unit configured to detect that the voltage supplied to the control unit has become a predetermined value or less when the control unit is in a state where a control signal for driving the starter is being output, the control unit And an output holding unit for holding the state of the control signal output from.
According to this configuration, since the output holding unit maintains the state of the control signal that drives the starter even when the battery is in a low voltage state, the engine start control device can not only continue the engine start but also start the engine. Can be improved.

In the engine start control device, the control unit holds the state of the control signal output from the control unit when the voltage supplied to the control unit exceeds a predetermined value. When it is detected that the output holding unit is instructed to stop holding the state of the control signal output from the control unit, the output holding unit receives the control signal from the control unit. According to the command, holding of the state of the control signal output from the control unit is stopped.
According to this configuration, when the battery voltage becomes equal to or higher than the predetermined value, the output holding unit stops holding the state of the control signal that drives the starter. Return to the control state.

In the engine start control device, when the control unit detects that the output holding unit holds the state of the control signal output from the control unit, the generator for charging the battery generates power. It is characterized in that at least one control control is executed among a power generation amount increasing control process for controlling the power generation amount to be performed on the generator and an eco-run prohibiting control process for performing eco-run prohibiting control.
According to this structure, it can prevent that a battery will be in a low voltage state by increasing the electric power generation amount which the generator for charging a battery increases, or prohibiting eco-run.

In the engine start control device, the output holding unit further includes a time measuring unit that measures a time during which the state of the control signal output from the control unit is maintained, and the time measured by the time measuring unit is When a predetermined time is exceeded, the output holding unit stops holding the state of the control signal output from the control unit.
According to this configuration, when the battery voltage is so low that the engine cannot be started even after a predetermined time has elapsed, the start-up of the starter motor can be stopped to prevent the battery from rising.

In the engine start control device described above, a confirmation process for calculating a capacity of the battery and confirming a charge state of the battery before outputting a control signal for driving the starter, and a confirmation process of the battery confirmed by the confirmation process. A determination process for determining whether or not to output a control signal for driving the starter based on a charge state, and the output process outputs a control signal for driving the starter in the determination process. When it is determined that the starter is allowed to be output, a control signal for driving the starter is output, and when it is determined that the control signal for setting the starter is not allowed to be output in the determination process, A control signal for driving the starter is not output.
According to this configuration, since the control unit does not output a control signal for driving the starter when the battery is insufficiently charged, it is possible to prevent overdischarge of the battery and avoid being unable to start. .

  According to the present invention, it is possible not only to continue the engine start even when the battery is in a low voltage state, but also to improve the engine startability.

It is a lineblock diagram showing an example of an engine system to which the present invention is applied. It is a hardware block diagram showing the example of 1 structure of engine control ECU to which this invention is applied. It is a figure which shows an example of the hardware constitutions of a microcomputer. It is a functional block diagram which shows an example of the function which a microcomputer has. It is a flowchart which shows an example of the process which a power supply IC (output holding circuit) performs. It is a flowchart which shows an example of the process which a microcomputer performs at the time of starting. It is an example of the timing chart of the engine starting control using engine control ECU which does not apply the engine control apparatus of this invention. It is an example of the timing chart of engine starting control using engine control ECU to which the engine control device of the present invention is applied. It is an example of the timing chart of engine starting control using engine control ECU to which the engine control device of the present invention is applied.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described with reference to the accompanying drawings.

FIG. 1 is a configuration diagram showing an example of an engine system to which an engine start control device of the present invention is applied.
As shown in FIG. 1, an engine control ECU (Electronic Control Unit) 100, which is an embodiment of an engine start control device, includes an ignition switch (IG SW) 10, a starter switch (ST SW) 11, an engine rotation sensor 12, A battery 13, an accessory cut relay 14, a starter relay 16, and a communication bus 22 are connected. When the ignition switch 10 is turned on, the battery voltage is supplied and the engine control ECU 100 starts up. The starter switch 11 inputs a starter signal, which is a signal for requesting engine start, to the engine control ECU 100. The engine rotation sensor 12 inputs an engine rotation signal to the engine control ECU 100. The battery 13 supplies battery voltage to the engine control ECU 100.
The starter relay 16 is connected to the starter motor 17. The battery voltage is supplied to the starter motor 17 based on a starter output that controls opening and closing of the switch of the starter relay 16 output from the engine control ECU 100. The accessory cut relay 14 supplies battery voltage to the accessory ECU 15 based on an accessory cut output that controls opening and closing of the switch of the accessory cut relay 14 output from the engine control ECU 100.
Further, the engine control ECU 100 receives a starter ON / OFF signal that is a signal for monitoring the starter output that the engine control ECU 100 outputs to the starter relay 16. These signals and components are examples, and the engine control ECU 100 can be connected to other components and signals.

The engine control ECU 100 starts control for starting the engine (hereinafter abbreviated as engine start control) in response to the starter signal from the starter switch 11.
First, the engine control ECU 100 outputs a starter output to the starter relay 16 in order to drive a starter motor 17 that rotates the engine 18. Until the start of the engine 18 is completed, in order to efficiently use the voltage supplied by the battery 13 for driving the starter motor, it is necessary to stop the power supply to the accessory device mounted on the vehicle. Therefore, the engine control ECU 100 outputs an accessory cut output to the accessory cut relay 14 and turns off the accessory cut relay 14. When the accessory cut relay 14 is turned off, the accessory ECU 15 stops operating because it cannot receive power from the battery.

When the starter relay 16 is turned on by the starter output output from the engine control ECU 100, electric power is supplied from the battery 13 to the starter motor 17. When the starter motor 17 receiving the power supply is driven, the engine 18 is rotated and started.
When the start of the engine 18 is completed, the engine control ECU 100 ends the output of the starter output and the output of the accessory cut output. Whether or not the start of the engine 18 has been completed is determined by, for example, comparing an engine speed obtained from an engine speed signal acquired from the engine speed sensor 12 with a predetermined speed at which it can be determined that the engine 18 has been started. Can be determined.

Next, an example of the hardware configuration of the engine control ECU 100 to which the present invention is applied will be described with reference to FIG.
The engine control ECU 100 according to the present embodiment includes a CAN controller 19, an input circuit 20, a microcomputer (control unit) 40, an output circuit 21, and a power supply IC (Integrated Circuit) (output holding circuit) 30.

  The power supply IC 30 is connected to the battery 13. The power supply IC 30 supplies power to each part such as the CAN controller 19 and the microcomputer 40 constituting the engine control ECU 100 using the voltage supplied from the battery 13. That is, power supplied from the battery is supplied to the microcomputer 40 via the power supply IC 30. Note that the voltage required for normal operation (operation guarantee voltage) is lower in the power supply IC 30 than in the microcomputer 40. For example, the operation guarantee voltage of the power supply IC 30 is 2V while the operation guarantee voltage of the microcomputer 40 is 4V. That is, the power supply IC 30 can operate at a lower voltage than the microcomputer 40.

  The CAN controller 19 is connected to a communication bus 22 connected to the microcomputer 40 and another ECU (not shown), and communicates with other ECUs via the communication bus 22 using a CAN protocol. For example, the CAN controller 19 transmits the battery state acquired by the microcomputer 40, information for controlling eco-run, and the like to another ECU (not shown) via the communication bus 22. Here, eco-run refers to driving with good fuel consumption (that is, economy) and friendly to the global environment (that is, ecology).

  The input circuit 20 inputs an ignition switch 10, a starter switch 11, a starter on / off signal, and an engine rotation signal from the engine rotation sensor 12, converts them into signals that can be input to the microcomputer 40, and outputs them to the microcomputer 40.

  The microcomputer 40 outputs a control signal for turning on / off the starter relay 16 and the accessory cut relay 14 using the ignition switch 10, the starter switch 11, the starter on / off signal, and the engine rotation signal input from the input circuit 20. .

  The output circuit 21 receives a control signal output from the microcomputer 40, generates signals for driving the starter relay 16 and the accessory cut relay 14, and outputs them to them.

Here, since the engine start control performed by the engine start control device of the present invention is realized by the cooperation of the power supply IC 30 and the microcomputer 40, the power supply IC 30 and the microcomputer 40 will be described in more detail.
First, the configuration of the power supply IC 30 will be described with reference to FIG.
The power supply IC 30 includes a reset circuit 31, a low voltage detection circuit 32, an output holding circuit 33, and a timer circuit (timer unit) 34.

  The low voltage detection circuit 32 is a circuit that detects a low voltage state in which the battery voltage is lower than the reset voltage. The low voltage detection circuit 32 is connected to the reset circuit 31 and the output holding circuit 33. The low voltage detection circuit 32 outputs, to the reset circuit 31 and the output holding circuit 33, a low voltage detection output for notifying that the battery voltage has fallen below the reset voltage when the battery voltage of the battery 13 falls below the reset voltage. To do.

  The reset circuit 31 is connected to the low voltage detection circuit 32 and the microcomputer 40. When the low voltage detection output from the low voltage detection circuit 32 is input, the reset circuit 31 outputs a reset output for resetting the microcomputer 40 to the microcomputer 40. When the reset output is input from the reset circuit 31, the microcomputer 40 stops operating until the battery voltage of the battery 13 exceeds the reset voltage of the microcomputer 40.

  The output holding circuit 33 is connected to the output circuit 21, the low voltage detection circuit 32, and the microcomputer 40. The output holding circuit 33 monitors the starter output and the accessory cut output from the microcomputer 40. The output holding circuit 33 inputs the low voltage detection output from the low voltage detection circuit 32 and inputs the starter output of the microcomputer 40 until just before inputting the low voltage detection output to the microcomputer 40. Instead, a holding output for holding the starter output is output to the output circuit 21 in order to hold the starter output. Here, holding refers to continuing the output of the starter output.

The output circuit 21 that has received the hold output continues to output the starter output to the starter relay 16 and the accessory cut output to the accessory cut relay 14.
Thereby, even if the battery voltage becomes a low voltage state, the engine control ECU 100 can continue to output the starter output and the accessory cut output.

The output holding circuit 33 is connected to the timer circuit 34. The output holding circuit 33 inputs a signal (hereinafter referred to as a clock signal) output from the timer circuit 34 at a predetermined time interval, and counts the clock signal, thereby determining the time during which the output of the holding output is continued. Keep time. Then, the output holding circuit 33 stops outputting the holding output when measuring a predetermined time.
Here, the predetermined time refers to a time sufficient for the starter motor 17 to receive the supply of the battery voltage from the battery 13 and start the engine 18, for example, 10 seconds. The means for counting the predetermined time may be any configuration that can count the predetermined time even when the battery voltage is in a low voltage state. Moreover, although it is an installation place of the means for counting a predetermined time, it may be realized by being installed in the power supply IC 30 or may be realized by being installed outside the power supply IC 30.

Further, the microcomputer 40 is connected to the output holding circuit 33 and can acquire the holding output of the output holding circuit 33. When the microcomputer 40 acquires the hold output of the output holding circuit 33 when the battery voltage returns from the low voltage state, the microcomputer 40 outputs a hold clear signal, which is a signal for instructing the stop of the hold output, to the output holding circuit 33. The output holding circuit 33 that has received the holding clear signal stops outputting the holding output.
On the other hand, the microcomputer 40 outputs a starter output instead of the output holding circuit 33.

  The timer circuit 34 is connected to the output holding circuit 33. The timer circuit 34 outputs a clock signal to the output holding circuit 33.

Next, the configuration of the microcomputer 40 will be described with reference to FIGS.
FIG. 3 shows an example of the hardware configuration of the microcomputer 40.
The microcomputer 40 implements control processing by an input / output unit 41 that inputs and outputs signals, a central processing unit (CPU) 43 that reads and executes a program stored in a ROM (Read Only Memory) 44, and an ECU. The ROM 44 stores a program and the like, and a RAM (Random Access Memory) 42 that stores temporary data used when the program is executed.

When the ignition switch 10 is turned on, the microcomputer 40 is activated and the program stored in the ROM 44 is executed by the CPU 43. By this program, a predetermined control process is performed based on a starter signal from the starter switch 11 and the like. Various control data are acquired during this control process, and the acquired control data is stored in the RAM 42 and used for the subsequent control process.
Further, by the calculation by the CPU 43 of the program stored in the ROM 44, a battery state confirmation unit 45, a starter output / accessory cut output on / off unit 46, a holding clear signal output unit 47, a power generation amount increase control unit 48, An eco-run prohibition control unit 49 is configured.

FIG. 4 is an example of a functional block diagram of the microcomputer 40 realized by the cooperation of the hardware such as the CPU 43 described above and the software stored in the ROM 44.
The microcomputer 40 includes a battery state confirmation unit 45, a starter output / accessory cut output on / off unit 46, a holding clear signal output unit 47, a power generation amount increase control unit 48, and an eco-run prohibition control unit 49.

The battery state confirmation unit 45 is connected to the battery sensor 23, the water temperature monitor 24, and the starter output / accessory cut output on / off unit 46 via the communication bus 22. Here, the battery sensor 23 includes a temperature sensor that measures the battery liquid temperature and the battery water temperature, and a sensor that detects the battery voltage. The water temperature monitor 24 includes a temperature sensor that measures the engine water temperature.
Therefore, the battery state confirmation unit 45 obtains information such as the battery liquid temperature, the battery water temperature, and the battery voltage from the battery sensor 23, obtains information on the engine water temperature from the water temperature monitor 24, and confirms the charge state of the battery to confirm. The result is output to the starter output / accessory cut output on / off unit 46.

  The starter output / accessory cut output on / off unit 46 controls output of signals for driving the starter relay 16 and the accessory cut relay 14. The starter output / accessory cut output on / off unit 46 is connected to the battery state confirmation unit 45, the starter switch 11, the engine rotation sensor 12, the output holding circuit 33, the starter relay 16, and the accessory cut relay 14.

  When the starter output / accessory cut output on / off unit 46 receives a starter signal for requesting start of the engine from the starter switch 11, the starter output and the accessory cut output for turning off the accessory cut relay 14 are output. To do. The starter output / accessory cut output on / off unit 46 also outputs the starter output and the accessory cut output even when the hold output is acquired from the output holding circuit 33. However, when the state of charge of the battery input from the battery state confirmation unit 45 is not sufficient, the starter output / accessory cut output on / off unit 46 outputs the starter signal even if the start switch 11 is input. Even if the holding output is acquired from the holding circuit 33, the starter output and the accessory cut output are not performed.

  The starter output / accessory cut output on / off unit 46 stops the output of the starter output and the accessory cut output when the start of the engine is completed. The starter output / accessory cut output on / off unit 46 can determine whether or not the engine has been started based on the engine rotation signal from the engine rotation sensor 12.

The holding clear signal output unit 47 outputs a holding clear signal that instructs the output holding circuit 33 to stop holding output. The holding clear signal output unit 47 is connected to the output holding circuit 33. When the microcomputer 40 returns from the reset state due to the battery voltage returning from the low voltage state, the holding clear signal output unit 47 acquires the holding output output from the output holding circuit 33 and then outputs the holding output to the output holding circuit 33. A hold clear signal is output. This is because the starter output and accessory cut output held by the output holding circuit 33 are output by the starter output / accessory cut output on / off unit 46 after the battery voltage returns from the low voltage state.
The output holding circuit 33 that has input the holding clear signal from the holding clear signal output unit 47 stops outputting the holding output.

The power generation amount increase control unit 48 performs control to increase the amount of power generated by the generator for charging the battery. The power generation amount increase control unit 48 is connected to the output holding circuit 33 and the CAN controller 19. When the microcomputer 40 returns from the reset state due to the battery voltage returning from the low voltage state, the power generation amount increase control unit 48 acquires the holding output output from the output holding circuit 33, via the CAN controller 19. Control for increasing the power generation amount is performed on the generator or the ECU that controls the power generation amount of the power generator.
This is to increase the amount of power generated by the generator to increase the amount of charge of the battery and prevent the battery voltage from entering a low voltage state.

  The eco-run prohibition control unit 49 performs control to prohibit idling stop while a condition for prohibiting automatic engine stop is satisfied, such as immediately after the engine is started. The eco-run prohibition control unit 49 is connected to the output holding circuit 33 and the CAN controller 19. When the microcomputer 40 returns from the reset state due to the battery voltage returning from the low voltage state, the eco-run prohibition control unit 49 obtains the holding output output from the output holding circuit 33 and permits the eco-run via the CAN controller 19. The control signal for prohibiting the eco-run is transmitted to the eco-run control ECU that has determined the above.

  The battery state confirmation unit 45, the starter output / accessory cut output on / off unit 46, the holding clear signal output unit 47, the power generation amount increase control unit 48, and the eco-run prohibition control unit 49 have a CPU 43, ROM 44, RAM 42, This is realized by cooperation with the hardware of the input / output unit 41 and required software stored in the ROM 44.

  Next, an example of engine start control processing performed by the engine control ECU 100 will be described with reference to FIGS. 5 and 6.

FIG. 5 is a flowchart illustrating an example of processing performed by the power supply IC 30.
The power supply IC 30 determines whether or not the battery voltage is in a low voltage state using the low voltage detection circuit 32 connected to the battery 13 (step S11).
When the power supply IC 30 determines that the low voltage detection circuit 32 is in the low voltage state (step S11 / YES), the starter immediately before the microcomputer 40 enters the low voltage state using the output holding circuit 33 connected to the microcomputer 40. It is confirmed whether output processing for outputting output has been performed (step S12).

  When the microcomputer 40 is performing the starter output (step S12 / YES), the power supply IC 30 outputs the holding output Hi from the output holding circuit 33 to the output circuit 21 (step S13). The output circuit 21 that has received the holding output from the power supply IC 30 continues to output the starter output and the accessory cut output. Thus, even when the battery voltage is in a low voltage state, the engine control ECU 100 can continue to output the starter output and the accessory cut output, and can continue the engine start control.

  Next, the power supply IC 30 causes the timer circuit 34 to count up a holding state count value for measuring the time during which the output holding circuit 33 continues to output the holding output Hi (holding state) (step S14). ).

  Next, the power supply IC 30 determines whether or not a hold clear signal for instructing to stop the hold output is received from the microcomputer 40 (step S15). This is because when the battery voltage returns from the low voltage state, the microcomputer 40 instructs the output holding circuit 33 to stop the Hi output of the holding output if the output holding circuit 33 outputs the holding output Hi. .

  When receiving the hold clear signal from the microcomputer 40 (step S15 / YES), the power supply IC 30 sets the hold output from the output hold circuit 33 to Lo output (step S17). Then, the power supply IC 30 clears the holding state count value (step S18) and ends the process.

Even when the power supply IC 30 has not received the hold clear signal from the microcomputer 40 (step S15 / NO), when the hold state count value becomes equal to or greater than the predetermined value (step S16 / YES), the power supply IC 30 The retained output is set to Lo output (step S17).
Thus, when the battery voltage is so low that the engine cannot be started even after a predetermined time has elapsed, the starter motor 17 is not driven, and the battery can be prevented from running out.

  While the holding state count value is not equal to or greater than the predetermined value (step S16 / NO), the power supply IC 30 outputs the holding output Hi from the output holding circuit 33 and keeps the starter output (step S13).

FIG. 6 is a flowchart showing an example of processing that the microcomputer 40 performs at startup.
When the microcomputer 40 is activated, it first prohibits eco-run (step S21). Then, the microcomputer 40 determines whether or not a starter signal is input from the starter switch 11 (step S22).

  When the microcomputer 40 receives an input of a starter signal from the starter switch 11 (step S22 / YES), the microcomputer 40 starts engine start control, outputs a starter output Hi to the starter relay 16, and an accessory cut to the accessory cut relay 14. The output is Hi (step S23).

  When the starter signal is not input from the starter switch 11 (step S22 / NO), the microcomputer 40 confirms whether or not the holding output for holding the starter output is output from the output holding circuit 33 (step S24). ). This is because when the output holding circuit 33 outputs the holding output Hi, the microcomputer 40 can determine that the battery voltage is in the low voltage state while the microcomputer 40 is outputting the starter output.

  If the output holding circuit 33 does not output the holding output Hi (step S24 / NO), the microcomputer 40 ends the process because it has not been reset during the engine start control. On the other hand, when the output holding circuit 33 outputs the holding output Hi (YES in step S24), the microcomputer 40 outputs a holding clear signal to the output holding circuit 33 (step S25).

  Next, the microcomputer 40 determines whether or not the engine has been started (step S26). The determination of whether or not the engine has been started can be determined based on, for example, an engine rotation signal acquired from the engine rotation sensor 12 when the engine speed has exceeded a predetermined value. .

  The microcomputer 40 ends the process when the start of the engine is completed (step S26 / YES). If the engine has not been started (step S26 / NO), the microcomputer 40 determines whether or not the battery state is good (step S27). The battery state can be confirmed by, for example, obtaining the voltage and current of the battery 13 from the battery sensor 23 and calculating the charging rate of the battery 13. Further, the battery liquid temperature and the battery water temperature can be obtained from the battery sensor 23, the engine water temperature can be obtained from the water temperature monitor 24, and the state of charge of the battery can be confirmed in combination with the charging rate of the battery 13 described above.

If the microcomputer 40 determines that the state of charge of the battery is not good, the engine start process is terminated (step S27 / NO).
As a result, when the state of charge of the battery is bad, the engine is not started, so that the battery can be protected and it is possible to prevent the engine from being unable to start.

  When the battery state is good (step S21 / YES), the microcomputer 40 turns on the reset history flag (step S28). The reset history flag is a flag indicating that engine start processing has been performed using the retained output from the output retaining circuit 33 because the battery has entered a low voltage state. Therefore, when the reset history flag is ON, the microcomputer 40 sets a condition for shifting from the eco-run prohibited state to the eco-run permitted state in the normal engine control performed following the processing performed by the microcomputer 40 described above at the time of normal control. Control to increase the amount of power generated by the generator. Thereby, it can prevent that a battery voltage will be in a low voltage state.

  Next, the microcomputer 40 outputs the starter output Hi to the starter relay 16, and outputs the accessory cut output Hi to the accessory cut relay 14 (step S23). Thereby, the microcomputer 40 can recover the control state before the reset.

  When the process of step S23 ends, the microcomputer 40 determines whether the engine start is completed (step S28). If the engine start has not been completed (NO in step S29), the microcomputer 40 sets the starter output and the accessory cut output to Hi output until the engine start is completed (step S23 and step S28).

  When the start of the engine is completed (step S28 / YES), the microcomputer 40 sets the starter output and the accessory cut output to Lo output (step S30).

  Here, correspondence between the CPU that executes each process executed by the microcomputer 40 and the functional block diagram of FIG. 4 will be described. The CPU that executes the process of checking the state of charge of the battery in step S22 corresponds to the battery state confirmation unit 45. The CPU that executes the holding clear signal output processing in steps S24 and S25 corresponds to the holding clear signal output unit 47. The CPU that executes the process of prohibiting the eco-run in step S 26 corresponds to the eco-run prohibition control unit 49. The CPU that executes the process of increasing the power generation amount of the power generator in step S27 corresponds to the power generation amount increase control unit 48. The CPU that executes the processing for outputting or stopping output of the starter output and accessory cut output in step S23 and step S28 corresponds to the starter output / accessory cut output on / off unit 46.

Next, the relationship between signals output from each component of the present invention will be described with reference to time charts of FIGS.
First, the engine start control in the case where the battery voltage does not fall below the reset voltage will be described using FIG. FIG. 7 is a time chart showing engine start control by the engine control ECU 100 to which the present invention is applied.
When the starter switch 11 is turned on (A), the microcomputer 40 switches the starter output and the accessory cut output from Lo to Hi (B and C). By the starter output and accessory cut output of the microcomputer 40, the signal output from the starter output connector end in the output circuit 21 is switched from Lo to Hi, and the accessory cut output connector end is switched from Hi to Lo (D and E). . Further, the starter ON / OFF signal, which is a feedback signal of the starter output from the microcomputer 40, is also switched from Hi to Lo (G).
When the starter motor 17 is driven by the starter output, the engine rotates, and the frequency of the engine rotation signal from the engine rotation sensor 12 increases (F). In the figure, the narrower the hatching interval, the higher the engine speed.
Here, since a large starting current is required to start the engine from the engine stopped state, the battery voltage temporarily decreases (a). However, since the battery voltage does not fall below the reset voltage, the microcomputer 40 can continue to output the starter output and the accessory cut output. Further, since the holding output does not become the Hi output, the power supply IC 30 does not start counting up the holding state count value, and the holding state count value remains 0. The holding clear threshold value is a threshold value set to determine the timing for ending the engine start control by switching the holding output from the Hi output to the Lo output.

  When the engine start is completed, the microcomputer 40 stops the starter output and the accessory cut output, and the engine start control ends (H and I).

  As can be seen from FIG. 7, in the engine control ECU 100 to which the present invention is applied, the starter output can be continuously output from the microcomputer 40 when the battery voltage does not fall below the reset voltage during the engine start control. When the battery voltage does not fall below the reset voltage, the conventional engine control ECU also has a time chart similar to FIG.

Next, engine start control when the battery voltage is lower than the reset voltage will be described.
FIG. 8 is a time chart showing engine start control by a conventional engine control ECU.
The relationship of each signal output from each component from when the starter switch 11 is turned on until the battery voltage decreases is not different from that in FIG. Therefore, the relationship between the signals after the battery voltage is lowered (a) and the reset voltage is lowered will be described.
When the battery voltage falls below the reset voltage, the low voltage detection circuit 32 switches the low voltage detection output from Lo to Hi (H). Upon receiving the low voltage detection output from the low voltage detection circuit 32, the reset circuit 31 switches the reset output from Hi to Lo (I). Then, the microcomputer 40 receiving the reset output from the reset circuit 31 is reset.

As the microcomputer 40 is reset, the starter output and accessory cut output return from Hi to Lo (J and K). Along with this, the connector end of the starter output and the connector end of the accessory output also return to the state before starting the engine start control (L and M). Also, the starter ON / OFF signal returns from Hi to Lo (Q).
Therefore, since the starter output is not output, the starter relay 16 is turned off and the power supply to the starter motor 17 is stopped. Therefore, the starter motor 17 cannot be driven, and the engine 18 continues to rotate due to inertia, but the rotational speed gradually decreases and the rotation stops (P).

  Thereafter, when the battery voltage exceeds the reset voltage (b), the low voltage detection circuit 32 switches the low voltage detection output from Hi to Lo, and accordingly, the reset output switches from Lo to Hi. The microcomputer 40 that has not received the reset output returns from the reset, but the engine start control cannot be continued because the control state before the reset cannot be recovered. In addition, since the microcomputer 40 cannot output a starter output even during resetting, in the conventional engine control ECU, engine start control is stopped while the battery voltage is in a low voltage state. Therefore, the startability of the engine was bad.

FIG. 9 is a time chart showing engine start control by the engine control ECU 100 to which the present invention for solving the above problem is applied.
In FIG. 9 as well, the relationship between the signals after the battery voltage falls below the reset voltage will be described.
In the engine control ECU 100 according to the present invention, when the battery voltage decreases (a) and falls below the reset voltage, the low voltage detection circuit 32 switches the low voltage detection output from Lo to Hi (H). Upon receiving the low voltage detection output from the low voltage detection circuit 32, the reset circuit 31 switches the reset output from Hi to Lo (I). Then, the microcomputer 40 receiving the reset output from the reset circuit 31 is reset. However, the output holding circuit 33 that has received the low voltage detection output from the low voltage detection circuit 32 outputs the holding output to the output circuit 21 as Hi (J). The output circuit 21 that has received the hold output holds the output at the connector end. Further, the timer circuit 34 starts counting up the holding state count value (A).

  Since the microcomputer 40 is reset, the starter output and the accessory cut output output from the microcomputer 40 are returned from Hi to Lo to the state before the engine start control (K and L). Further, since the starter output is switched from Hi to Lo, the starter ON / OFF signal is also switched from Hi to Lo (O).

Here, in the engine control ECU to which the present invention is not applied, as the microcomputer 40 stops the output of the starter output and the accessory cut output, the output at the connector end also returns to the state before the engine start control.
However, in the engine control ECU 100 to which the present invention is applied, the output holding circuit 33 outputs a signal obtained by switching the holding output from Lo to Hi to the output circuit 21. Since the output circuit 21 that has received the holding output holds the output at the connector end, the starter output and the accessory cut output at the connector end are maintained in the state before entering the low voltage state (M and N). Further, the holding state count value is counted up while the holding output is the Hi output.

  Thereafter, when the battery voltage recovers and exceeds the reset voltage, the low voltage detection circuit 32 switches the low voltage detection output from Hi to Lo (P), and accordingly, the reset output from the reset circuit 31 also switches from Lo to Hi. Change (Q). The microcomputer 40 returns from the reset state.

When the microcomputer 40 returns from the reset state and acquires the holding output output by the output holding circuit 33, the microcomputer 40 outputs a holding clear signal (R). The output holding circuit 33 switches the holding output from Hi to Lo according to the holding clear signal (S).
The microcomputer 40 outputs a starter output and an accessory cut output in place of the output holding circuit 33 (T and U). Each connector end receives a starter output and an accessory cut output from the microcomputer 40, and continues output of each output (V and W). Since the holding output is switched from Hi to Lo before the holding state count value exceeds the holding clear threshold, the holding state count value is reset and returns to 0 (B).
Therefore, in the engine control ECU 100 to which the present invention is applied, after the battery voltage returns from the low voltage state, the control state before the low voltage state can be recovered.

  When the engine start is completed, the microcomputer 40 stops the starter output and the accessory cut output, and the engine start control ends (X and Y).

  As is apparent from the above description, according to the present embodiment, even when the battery voltage of the battery 13 is in a low voltage state, the output holding circuit 33 outputs the holding output to the output circuit 21, so that the starter relay The starter output can be continuously output to 16, and the engine start control can be continued. In addition, after the battery voltage returns from the low voltage state, the microcomputer 40 can recover the control state before the low voltage state by checking whether the output holding circuit 33 outputs the holding output. Engine startability is improved.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments according to the present invention, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.
For example, the holding output output by the output holding circuit 33 is not used for holding the starter output, and the microcomputer 40 prohibits the control process for increasing the amount of power generated by the generator for charging the battery 13 and the eco-run. It can also be used only for performing control processing.

  The program executed by the engine control ECU 100 can be provided by being stored and distributed in a magnetic disk, an optical disk, a semiconductor memory, or other recording media, or distributed via a network.

  Further, a part or all of the software processing realized by the microcomputer 40 reading the software program stored in the ROM 44 and executed by the CPU 43 may be realized by hardware.

  Although the embodiment described above has shown the embodiment in the engine control ECU, the present invention is not limited to this, and a control is provided that includes a microcomputer and must continue control even when the battery voltage falls below the operating voltage of the microcomputer. Application to the device is possible. In the above-described embodiment, the present invention is applied to an engine start control device that performs engine start control based on a manual operation (an on operation of the starter switch 11 by a user). However, the present invention can also be applied to a control device that performs automatic engine start control by eco-run (idling stop) control or the like.

10 ... Ignition switch (IG SW)
11. Starter switch (ST SW)
12 ... Engine rotation sensor 13 ... Battery 14 ... Accessory cut relay 15 ... Accessory ECU
DESCRIPTION OF SYMBOLS 16 ... Starter relay 17 ... Starter motor 18 ... Engine 19 ... CAN controller 20 ... Input circuit 21 ... Output circuit 22 ... Communication bus 23 ... Battery sensor 24 ... Water temperature monitor 30 ... Power supply IC
31 ... Reset circuit 32 ... Low voltage detection circuit 33 ... Output holding circuit 34 ... Timer circuit 40 ... Microcomputer 41 ... Input / output unit 42 ... RAM
43 ... CPU
44 ... ROM
45 ... Battery state confirmation unit 46 ... Starter output / accessory cut output ON / OFF unit 47 ... Holding clear signal output unit 100 ... Engine control ECU

Claims (5)

An engine start control device for controlling engine start by driving a starter,
A control unit for outputting a control signal for driving the starter;
The voltage supplied to the control unit is less than or equal to a predetermined value when a control signal for driving the starter is output from the control unit. When detecting that, an output holding unit that holds the state of the control signal output from the control unit,
An engine start control device comprising: When the control unit detects that the output holding unit holds the state of the control signal output from the control unit when the voltage supplied to the control unit exceeds a predetermined value, Executing instruction processing to instruct the output holding unit to stop holding the state of the control signal output from the control unit;
The engine start control device according to claim 1, wherein the output holding unit stops holding the state of the control signal output from the control unit in response to the command from the control unit.   When the control unit detects that the output holding unit holds the state of the control signal output from the control unit, the control unit performs control to increase the amount of power generated by the generator for charging the battery. 3. The engine according to claim 1, wherein at least one control control is executed among a power generation amount increase control process performed on the generator and an eco-run prohibition control process for performing eco-run prohibition control. 4. Start control device. The output holding unit further has a time measuring unit for measuring the time during which the state of the control signal output from the control unit is kept,
The output holding unit stops holding the state of the control signal output from the control unit when the time counted by the time counting unit exceeds a predetermined time. The engine start control device according to any one of claims 1 to 3. The control unit calculates the capacity of the battery before outputting a control signal for driving the starter and confirms the state of charge of the battery, and confirms the state of charge of the battery confirmed in the confirmation process. A determination process for determining whether or not to permit the output of a control signal to drive the starter based on
The output process outputs a control signal for setting the starter in a driving state when the determination process is permitted to output a control signal for setting the starter in a driving state. 5. The control signal for driving the starter is not output when it is determined not to permit the output of the control signal for setting the starter to the drive state. 6. Engine start control device.

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