JP6530597B2 - Engine control unit - Google Patents

Description

  The present invention relates to an engine control device.

  In order to reduce exhaust gas and suppress fuel consumption, a vehicle in which the engine is automatically stopped when a predetermined engine stop condition is satisfied, such as waiting for a signal, has been put to practical use. When the accelerator is operated in the automatic stop state, the engine is automatically restarted.

  In a vehicle provided with an automatic stop function of an engine, there is a concern that the storage amount of the battery may be rapidly reduced if a flashlight such as a headlight is used during the automatic stop of the engine. A technology has been proposed that automatically dims or extinguishes a flame when the automatic stop state of the engine continues for a predetermined time or more (see Patent Document 1).

  On the other hand, in straddle-type vehicles such as motorcycles, scooters and mopeds, it is desirable to turn on the headlights and taillights when the vehicle is stopped, such as waiting for a signal, in order to improve visibility from surrounding vehicles.

Unexamined-Japanese-Patent No. 2004-108191

  Since the battery of the saddle-ride type vehicle has a smaller capacity than the battery of the four-wheeled vehicle, the amount of stored electricity is likely to decrease due to the use of the flames while the engine is stopped. When the starter motor is driven for automatic restart of the engine in a state where the storage amount is reduced, the central processing unit (CPU) in the engine control device may be reset due to a decrease in battery voltage. When the battery voltage recovers and the CPU is restarted, is the engine control state at the time of CPU reset occurrence being automatic stop state or not automatic stop state in order to perform appropriate engine control? It is preferable to determine

  By storing flag information indicating that the current engine control state is the automatic stop state in nonvolatile memory such as flash memory or EEPROM, it is possible to read information before reset even after CPU reset. .

  However, when the number of times of rewriting of the flag information approaches the upper limit of the number of times of rewriting of the non-volatile memory, the reliability of the flag information decreases. Furthermore, when the number of times of rewriting of the flag information exceeds the upper limit of the number of times of rewriting of the non-volatile memory, rewriting may become impossible.

  An object of the present invention is to provide an engine control apparatus capable of holding information indicating the control state of the engine immediately before the reset even if the control unit of the engine control apparatus is reset due to a temporary decrease in battery voltage. is there.

An engine control apparatus according to a first aspect of the present invention is
An engine control apparatus for controlling an engine of a vehicle, comprising:
An instantaneous interruption determination circuit including a first capacitor, and a first resistor charging / discharging the first capacitor with a first time constant;
A holding circuit including a second capacitor, and a second resistor that charges and discharges the second capacitor with a second time constant longer than the first time constant;
A control unit that controls the engine based on voltage states of the first capacitor and the second capacitor;
The control unit discharges the second capacitor and maintains the charge state of the first capacitor when the condition for transitioning the engine to the automatic stop state is satisfied, and transitions to the automatic stop state . When the condition to be satisfied is not satisfied, the charging of the first capacitor is started after the charging of the second capacitor is started, and the voltage of the first capacitor is restarted when restarted from the low voltage reset. Is equal to or higher than the first voltage threshold and the voltage of the second capacitor is less than the second voltage threshold, it is determined that the state immediately before the low voltage reset is the automatic stop state .

In the engine control apparatus according to the second aspect of the present invention, in addition to the configuration of the engine control apparatus according to the first aspect,
The controller starts charging the first capacitor when a predetermined standby time elapses after the controller starts charging the second capacitor.

In the engine control apparatus according to the third aspect of the present invention, in addition to the configuration of the engine control apparatus according to the first aspect,
The controller starts charging the first capacitor when the voltage of the second capacitor reaches a voltage threshold after the controller starts charging the second capacitor.

In the engine control apparatus according to the fourth aspect of the present invention, in addition to the configuration of the engine control apparatus according to the first to third aspects,
A sum of an assumed value of the instantaneous power interruption time and an elapsed time until the control unit determines the control state of the engine based on the voltage state of the first capacitor and the second capacitor after power is restored The second time constant is longer than the value.

  In the engine control device according to the first aspect, for example, the discharge of the second capacitor is started when the condition for transitioning the engine to the predetermined control state is satisfied, and the charge state of the first capacitor is maintained. Do. When the control unit is reset due to a temporary drop in voltage (a momentary loss of power), the control state of the engine immediately before the voltage drop is controlled by detecting the charge / discharge state of the second capacitor It can be determined whether or not it was a state. Whether a reset due to a momentary loss of power or a reset due to normal power on can be determined based on the charge / discharge state of the first capacitor.

  Furthermore, for example, when the conditions for transitioning the engine to the predetermined control state are not satisfied and the second capacitor is being discharged, charging of the second capacitor is started, and then the first capacitor is Charging starts. For this reason, the voltage of the second capacitor is relatively low, and a period in which the voltage of the first capacitor is relatively high (period in which the charging of the second capacitor is insufficient) hardly occurs.

  If a momentary loss of power occurs while the second capacitor is not fully charged, the condition should be transitioned to the predetermined control state even though the condition to cause the engine to transition to the predetermined control state is not satisfied Is falsely determined to be satisfied. In the engine control system according to the first aspect, since the period during which the second capacitor is not sufficiently charged is unlikely to occur, it is possible to reduce the probability of occurrence of erroneous determination.

  In the engine control device according to the second aspect and the engine control device according to the third aspect, it is possible to further reduce the occurrence probability of the erroneous determination.

  In the engine control apparatus according to the fourth aspect, the charge state of the second capacitor can be substantially maintained until the voltage state of the second capacitor is determined after the power is shut off. Therefore, it is possible to determine the control state of the engine based on the voltage state of the second capacitor at the point of time when the power is shut off.

FIG. 1A is a block diagram and an equivalent circuit diagram of an engine control device according to an embodiment, and FIG. 1B is an equivalent circuit diagram of an instantaneous interruption determination circuit and a holding circuit of an engine control device according to a modification of the embodiment. FIG. 2 is a graph showing an example of a temporal change of the power supply voltage, the voltage of the first capacitor of the instantaneous interruption judging circuit, and the voltage of the second capacitor of the holding circuit. FIG. 3A is a chart showing the relationship between the voltage of the first capacitor and the second capacitor after resetting of the control unit and the determination result of the engine control state, and FIG. 3B is a control of the engine control device according to the embodiment. It is a flowchart of the process performed after the reset of a part. FIG. 4 is a graph showing an example of a temporal change of the power supply voltage in the engine control apparatus according to the comparative example, the voltage of the first capacitor of the short break judging circuit, and the voltage of the second capacitor of the holding circuit.

  FIG. 1A shows a block diagram of an engine control apparatus 10 according to an embodiment. The engine control device 10 includes a control unit 13, an instantaneous loss determination circuit 11, and a holding circuit 12. For example, a central processing unit (CPU) is used for the control unit 13.

  The instantaneous loss determination circuit 11 is formed of a series circuit of a first capacitor C1 and a first resistor R1. The first resistor R1 is connected to the first output port 13A of the control unit 13, and the first capacitor C1 is grounded. Charging and discharging of the first capacitor C1 are performed through the first output port 13A. An interconnection point between the first resistor R1 and the first capacitor C1 is connected to the first input port 13B of the control unit 13. Therefore, the first voltage V1 between the terminals of the first capacitor C1 is applied to the first input port 13B. When the first output port 13A is pulled up to the voltage Vdd, the first capacitor C1 is charged through the first resistor R1 with a first time constant. When the first output port 13A is pulled down to the ground voltage, the first capacitor C1 discharges with the first time constant via the first resistor R1.

  The holding circuit 12 is formed of a series circuit of a second capacitor C2 and a second resistor R2. The second resistor R2 is connected to the second output port 13C of the control unit 13, and the second capacitor C2 is grounded. The second capacitor C2 is charged and discharged through the second output port 13C. An interconnection point between the second resistor R2 and the second capacitor C2 is connected to the second input port 13D of the control unit 13. Therefore, the second voltage V2 between the terminals of the second capacitor C2 is applied to the second input port 13D. When the second output port 13C is pulled up to the voltage Vdd, the second capacitor C2 is charged via the second resistor R2 with a second time constant. When the second output port 13C is pulled down to the ground voltage, the second capacitor C2 discharges with a second time constant via the second resistor R2. The second time constant is longer than the first time constant.

  Information such as the vehicle speed of the vehicle on which the engine control device 10 is mounted, the coolant temperature, the engine speed, the automatic stop control selection switch, the ignition key, etc. is input to the engine control device 10. The automatic stop control selection switch is for the driver to select whether to enable or disable the automatic stop function of the engine. The engine control device 10 controls the starter 20 and the engine 21 based on the current engine control state.

  The input impedances of the first input port 13B and the second input port 13D of the control unit 13 are sufficiently large compared to the resistance values of the first resistor R1 and the second resistor R2, and are substantially infinite. I can think of it. The output impedances of the first output port 13A and the second output port 13C of the control unit 13 are sufficiently smaller than the resistance values of the first resistor R1 and the second resistor R2, and considered to be substantially zero. be able to.

  The operations of the instantaneous loss determination circuit 11 (FIG. 1A) and the holding circuit 12 (FIG. 1A) will be described with reference to FIGS. 2, 3A, and 3B.

  The upper portion of FIG. 2 shows the temporal change of the power supply voltage Vs applied to the engine control device 10, the middle portion shows the temporal change of the first voltage V1 of the first capacitor C1, and the lower portion shows the second capacitor The time change of the 2nd voltage V2 of C2 is shown.

  During the period up to time t0 shown in FIG. 2, the power supply voltage Vs, the first voltage V1 of the first capacitor C1, and the second voltage V2 of the second capacitor C2 are approximately 0V. This state corresponds to, for example, a state in which the ignition key is turned off.

  When the ignition key is turned on at time t0, the power supply voltage Vs rises to the voltage Vdd. When the power supply voltage Vs rises, the reset process of the control unit 13 of the engine control device 10 is started. At time t1 after the start of the reset process, the control unit 13 reads the first voltage V1 of the first capacitor C1 and the second voltage V2 of the second capacitor C2.

  The control unit 13 determines whether the automatic stop condition of the engine is satisfied based on the first voltage V1 and the second voltage V2. A specific determination method will be described later with reference to FIG. 3B.

  At time t0 shown in FIG. 2, since the ignition key is turned on, the automatic stop condition is not satisfied. In this case, the control unit 13 (FIG. 1A) first starts to charge the second capacitor C2 by pulling up the second output port 13C to the voltage Vdd. This causes the second voltage V2 to rise toward the voltage Vdd with a second time constant. After charging of the second capacitor C2 is started, at time t2, the control unit 13 pulls up the first output port 13A to the voltage Vdd to start charging of the first capacitor C1. Thus, the first voltage V1 rises toward the voltage Vdd with a first time constant. Since the second time constant is longer than the first time constant, the rising slope of the second voltage V2 is gentler than the rising slope of the first voltage V1.

  An example in which the power is momentarily disconnected during a period from time t3 to time t4 will be described. When the power is shut off at time t3, the first output port 13A and the second output port 13C (FIG. 1A) are pulled down to the ground voltage. For this reason, the first capacitor C1 is discharged, and the first voltage V1 decreases at a first time constant. Furthermore, the second capacitor C2 is discharged, and the second voltage V2 decreases at a second time constant.

  When the power is restored at time t4, the first output port 13A and the second output port 13C are in a high impedance state. Therefore, the first voltage V1 and the second voltage V2 are maintained at the values at the time t4.

  When the reset process of the control unit 13 (FIG. 1A) is started at time t4, the control unit 13 controls the first voltage V1 of the first capacitor C1 and the first voltage V1 at time t5 as in the time t1. The second voltage V2 of the second capacitor C2 is read. Since the power supply interruption time is short, the first voltage V1 has not dropped to the first voltage threshold Vt1, and the second voltage V2 has not dropped to the second voltage threshold Vt2. In other words, the first time constant and the second time constant are designed to be longer than the assumed value of the power failure time. As an example, the second voltage threshold Vt2 is the same as the first voltage threshold Vt1, and is 1/2 of the voltage Vdd.

  After the power is restored at time t4, when the first output port 13A and the second output port 13C (FIG. 1A) are pulled down to the ground voltage, the first capacitor C1 and the first capacitor C1 are not connected until time t5. Discharge of the capacitor C2 of 2 continues. In this case, the estimated value of the instantaneous power interruption time, and the elapsed time from the point of time of power supply recovery until the control unit 13 determines the control state of the engine based on the first voltage V1 and the second voltage V2 It is preferable to make the first time constant and the second time constant longer than the total value of t (time from time t3 to time t5).

  When the first voltage V1 is equal to or higher than the first voltage threshold Vt1 and the second voltage V2 is equal to or higher than the second voltage threshold Vt2, the control unit 13 (FIG. 1A) is in the non-automatic stop state of the engine. It is determined that a momentary loss of power has occurred. When the state of the engine before momentary interruption is in the non-automatic stop state, the control unit 13 starts charging of the second capacitor C2 and then charges the first capacitor C1 as in the time t1. Start. In the period until time t6, the first capacitor C1 and the second capacitor C2 are charged to the voltage Vdd.

  FIG. 2 shows an example in which the condition for automatic engine stop is satisfied at time t6 and the engine is automatically stopped. When it is determined at time t6 that the automatic stop condition of the engine is satisfied, the control unit 13 (FIG. 1A) discharges the second capacitor C2 by pulling down the second output port 13C to the ground voltage. The charge state of the first capacitor C1 is maintained. When a time sufficiently longer than the time constant (second time constant) of the discharge of the second capacitor C2 passes, the second voltage V2 becomes almost 0V.

  FIG. 2 shows an example in which the power supply is interrupted momentarily during a period from time t7 to time t8 when the second voltage V2 is approximately 0V. At time t7, the second voltage V2 is less than the second voltage threshold Vt2. When the power is shut off at time t7, the first capacitor C1 is discharged, and the first voltage V1 decreases at a first time constant. At time t8 when the power is restored, the first voltage V1 is equal to or higher than the first voltage threshold Vt1. After time t8, the first voltage V1 is maintained at the value at time t8.

  When the reset process of the control unit 13 (FIG. 1A) is activated at time t8, the control unit 13 controls the first voltage of the first capacitor C1 at time t9, as at time t1 and time t5. Read V1 and the second voltage V2 of the second capacitor C2. The first voltage V1 has not dropped to the first voltage threshold Vt1 because the power supply interruption time is short. The second voltage V2 is 0V.

  When the first voltage V1 is equal to or higher than the first voltage threshold Vt1 and the second voltage V2 is lower than the second voltage threshold Vt2, the control unit 13 (FIG. 1A) determines that the engine is in the automatic stop state. It is determined that a momentary loss of power has occurred. When the state of the engine before the momentary interruption is the automatic stop state, the control unit 13 starts charging of the first capacitor C1. The second capacitor C2 is maintained in the discharged state.

  In FIG. 3A, the first voltage V1 of the first capacitor C1 and the second voltage V2 of the second capacitor C2 when the control unit 13 (FIG. 1A) is reset, and the judgment result of the engine control state Indicates the correspondence.

  If the time until the power is restored after the power supply to the control unit 13 is shut off is sufficiently long compared to the first time constant, the time at which the power is restored (for example, time t0 in FIG. 2) The voltage V1 of 1 is reduced to less than the first voltage threshold Vt1. In this case, it is determined that the control unit 13 has been reset by factors other than the momentary power loss, specifically, the turning on of the ignition key.

  When it is determined in the reset process of the control unit 13 that the first voltage V1 is equal to or higher than the voltage threshold, it is determined that the control unit 13 has been reset due to a momentary loss of power. If the engine is in the automatic stop state at the time of the occurrence of a momentary power loss, the second voltage V2 is less than the second voltage threshold Vt2, as in the voltage state at time t7 in FIG. Therefore, when the first voltage V1 is equal to or higher than the first voltage threshold Vt1 and the second voltage V2 is lower than the second voltage threshold Vt2, a momentary power interruption occurs when the engine is in the automatic stop state. Is determined to have occurred.

  If the engine is not in the automatic stop state (non-automatic stop state) at the moment of a power failure, as in the voltage state at time t3 in FIG. 2, the second voltage V2 is the second voltage threshold It is Vt2 or more. Therefore, when the first voltage V1 is equal to or higher than the first voltage threshold Vt1 and the second voltage V2 is equal to or higher than the second voltage threshold Vt2, the momentary decrease of the power supply occurs when the engine is in the non-automatic stop state. It is determined that a break has occurred.

  FIG. 3B shows a flowchart of processing executed by control unit 13 when control unit 13 (FIG. 1A) is reset. When the control unit 13 is reset due to an ignition switch on or a momentary power loss, etc., in step S1, the first voltage V1 of the first capacitor C1 is read from the first input port 13B (FIG. 1A), The second voltage V2 of the second capacitor C2 is read from the second input port 13D. The fact that the control unit 13 is reset when the power supply voltage decreases is referred to as "low voltage reset".

  In step S2, it is determined whether the first voltage V1 of the first capacitor C1 is greater than or equal to the first voltage threshold Vt1. When the first voltage V1 is lower than the first voltage threshold Vt1, in step S6, it is determined that the control unit 13 has been activated by the normal ignition on, not by the instantaneous power interruption. This determination result corresponds to the determination result at time t1 in FIG.

  When it is determined in step S2 that the first voltage V1 is equal to or higher than the first voltage threshold Vt1, in step S3, the second voltage V2 of the second capacitor C2 is equal to or higher than the second voltage threshold Vt2. It is determined whether or not. The fact that the first voltage V1 is equal to or higher than the first voltage threshold Vt1 is considered to cause a momentary loss of power, as shown in FIG. 3A.

  When it is determined in step S3 that the second voltage V2 is equal to or higher than the second voltage threshold Vt2, in step S4, it is determined that the engine was other than in the automatic stop state at the time of power interruption. This determination result corresponds to the determination result at time t5 in FIG. If the second voltage V2 is lower than the second voltage threshold Vt2, it is determined in step S5 that the engine is in the automatic stop state at the moment of the power interruption. This determination result corresponds to the determination result at time t9 in FIG.

  When the cause of the low voltage reset of the control unit 13 is specified in any of steps S4 to S6, it is determined in step S7 whether the automatic stop condition of the engine is satisfied. This determination is performed based on the vehicle speed, the coolant temperature, the engine speed, the state of the automatic stop control selection switch, and the like input to the engine control device 10.

  If it is determined in step S7 that the automatic stop condition is satisfied, discharging of the second capacitor C2 (FIG. 1A) is started in step S8. Specifically, the second output port 13C is pulled down to the ground voltage. When the second output port 13C is already pulled down to the ground voltage, the discharging of the second capacitor C2 is continued by maintaining the pull-down state. The charge state of the first capacitor C1 is maintained. Step S8 corresponds to the process performed in the period from time t6 to time t7 in FIG.

  If it is determined in step S7 that the automatic stop condition is not satisfied, charging of the second capacitor C2 is started in step S9, and then charging of the first capacitor C1 is started. The charge start of the second capacitor C2 corresponds to the process at time t1 in FIG. 2, and the charge start of the first capacitor C1 corresponds to the process at time t2 in FIG. If charging of the second capacitor C2 has already been started, charging is continued as it is. This process corresponds to the process from time t1 to time t3 in FIG. If charging of the first capacitor C1 has already been started, charging is continued as it is. This process corresponds to the process from time t2 to time t3 in FIG.

  In the above embodiment, the control state of the engine at the time of the occurrence of a momentary power loss is stored by the charge stored in the second capacitor C2. Therefore, it is not necessary to use a non-volatile memory for storing the control state of the engine. As a result, it is possible to avoid a decrease in reliability due to the number of rewrites of the non-volatile memory approaching the upper limit of the number of rewrites. Furthermore, there is no need to perform maintenance work such as replacement of non-volatile memory.

  Next, the effect of making the second time constant of charge and discharge of the second capacitor C2 longer than the first time constant of charge and discharge of the first capacitor C1 will be described. If the second time constant is shorter than the first time constant, the second voltage V2 may be less than the second voltage threshold Vt2 at time t4 shown in FIG. If the second voltage V2 becomes less than the second voltage threshold Vt2 at time t4, it is erroneously determined that the engine is automatically stopped even though the engine is not automatically stopped at the moment of a power failure. It will By making the second time constant equal to or greater than the first time constant, this erroneous determination can be avoided.

  In the embodiment, since the first voltage threshold Vt1 and the second voltage threshold Vt2 are equal, when the second time constant is equal to the first time constant, the first voltage V1 is the first voltage at time t4. If it is more than threshold value Vt1, 2nd voltage V2 will also become more than 2nd voltage threshold value Vt2. Therefore, in theory, the first time constant may be equal to the second time constant. However, when the circuit constants of the instantaneous interruption determination circuit 11 and the holding circuit 12 (FIG. 1A) are designed so that the first time constant and the second time constant become equal, variations in manufacturing of the capacitor and the resistor occur. The second time constant may be shorter than the first time constant.

  Designing the circuit constants of the instantaneous interruption determination circuit 11 and the holding circuit 12 (FIG. 1A) such that the second time constant is longer than the first time constant, the component constants of the capacitor and resistor fall within the allowable range Even if the second time constant is shorter than the first time constant does not easily occur. Therefore, an erroneous determination is less likely to occur in the determination as to whether or not the engine is automatically stopped. In order to avoid an erroneous determination, the lower limit value within the range of the variation of the second time constant is within the range of the variation of the first time constant in consideration of the variation of the component constant of the capacitor and the resistor. It is preferable to determine design values of the first time constant and the second time constant so as to be longer than the upper limit value.

  Next, the effect of starting charging of the first capacitor C1 after starting charging of the second capacitor C2 in step S9 (FIG. 3B) will be described.

  FIG. 4 shows an example of a change in voltage according to a comparative example in which charging of the first capacitor C1 and the second capacitor C2 is simultaneously started. The ignition key is turned on at time t10, and step S9 (FIG. 3B) is executed at time t11. At this time, in the comparative example, charging of the first capacitor C1 and charging of the second capacitor C2 are simultaneously started. Since the first time constant is shorter than the second time constant, the rising slope of the first voltage V1 is steeper than the rising slope of the second voltage V2. The case where a momentary loss of power occurs at time t12 when the second voltage V2 has not risen to the second voltage threshold Vt2 will be described.

  Since the first time constant is shorter than the second time constant, the first voltage V1 exceeds the first voltage threshold Vt1 at time t12. The first voltage V1 is maintained above the first voltage threshold Vt1 also at time t13 when the power is restored. On the other hand, the second voltage V2 is less than the second voltage threshold Vt2. In this case, from the correspondence table shown in FIG. 3A, it may be erroneously determined that the engine has been in the automatic stop state when a power failure occurs.

  In the embodiment shown in FIG. 2, the charging of the first capacitor C1 is started at the time t2 when a certain elapsed time has elapsed from the time t1 at which the charging of the second capacitor C2 was started. Therefore, a period in which the first voltage V1 is equal to or higher than the first voltage threshold Vt1 and the second voltage V2 is lower than the second voltage threshold Vt2 is shorter than that in the example of FIG. It will not exist. In the example shown in FIG. 2, charging of the first capacitor C1 is started after the second voltage V2 exceeds the second voltage threshold Vt2. For this reason, a period in which the first voltage V1 is equal to or higher than the first voltage threshold Vt1 and the second voltage V2 is lower than the second voltage threshold Vt2 does not occur.

  As a waiting time (time from time t1 to time t2) from when charging of the second capacitor C2 is started to when charging of the first capacitor C1 is started, the first time constant and the second time constant are used. It is possible to set a fixed value in advance based on this. As an example, it is preferable to make the standby time longer than the time until the second voltage V2 reaches the second voltage threshold Vt2.

  If the standby time is too long, it takes a long time for the first voltage V1 to reach the first voltage threshold Vt1 from time t0. If, from time t0, the engine is automatically stopped during a period until the first voltage V1 reaches the first voltage threshold Vt1 and a momentary power loss occurs at restart, the engine is also automatically stopped. Regardless, it is erroneously determined that the control unit 13 (FIG. 1A) has been reset by turning on the ignition key. Since the period until the engine is automatically stopped after the ignition key is turned on is indefinite, in order to avoid this erroneous determination, when the second voltage V2 becomes equal to or higher than the second voltage threshold Vt2, It is preferable to start charging the first capacitor C1 early. As an example, after the ignition key is turned on, the engine is automatically stopped for the first time and discharging of the second capacitor C2 is started, until the second voltage V2 becomes lower than or equal to the second voltage threshold Vt2. If the voltage V1 of the voltage V1 is equal to or higher than the first voltage threshold Vt1, the automatic stop state can be accurately determined in the reset process after the power failure.

  Instead of predetermining the length of the waiting time, charging of the first capacitor C1 may be started based on the value of the second voltage V2. For example, when it is detected that the second voltage V2 has reached the second voltage threshold Vt2, charging of the first capacitor C1 may be started.

  FIG. 1B shows a block diagram and an equivalent circuit diagram of an engine control device 10 according to a modification of the embodiment. In this modification, the interconnection point between the first capacitor C1 and the first resistor R1 is connected to the first input port 13B via the third resistor R3. Furthermore, the interconnection point between the second capacitor C2 and the second resistor R2 is connected to the second input port 13D via the fourth resistor R4.

  When the power supplied to the engine control device 10 is shut off, the first input port 13B and the second input port 13D of the control unit 13 may be pulled down to the ground potential. When the input impedance of the first input port 13B at this time is equal to or lower than that of the first resistor R1, the time constant of discharge of the first capacitor C1 is the input impedance of the first input port 13B. It is affected by The third resistor R3 has a function of maintaining high effective input impedance when looking at the first input port 13B from the connection point between the first capacitor C1 and the first resistor R1. Similarly, the fourth resistor R4 has a function of maintaining high effective input impedance when the second input port 13D is viewed from the connection point between the second capacitor C2 and the second resistor R2. Have.

  When the first input port 13B and the second input port 13D maintain the high impedance state even when the power to the engine control device 10 is shut off, as shown in FIG. The connection point between the capacitor C1 and the first resistor R1 may be directly connected to the first input port 13B. Similarly, the connection point between the second capacitor C2 and the second resistor R2 may be directly connected to the second input port 13D.

  Although the present invention has been described above according to the embodiments, the present invention is not limited thereto. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

DESCRIPTION OF REFERENCE NUMERALS 10 engine control device 11 momentary interruption judging circuit 12 holding circuit 13 control device 13A first output port 13B first input port 13C second output port 13D second input port 20 starter 21 engine C1 first capacitor C2 first capacitor 2 capacitor R1 1st resistor R2 2nd resistor R3 3rd resistor R4 4th resistor V1 1st voltage V2 2nd voltage Vt 1 1st voltage threshold Vt 2 2nd voltage threshold

Claims (4)

An engine control apparatus for controlling an engine of a vehicle, comprising:
An instantaneous interruption determination circuit including a first capacitor, and a first resistor charging / discharging the first capacitor with a first time constant;
A holding circuit including a second capacitor, and a second resistor that charges and discharges the second capacitor with a second time constant longer than the first time constant;
A control unit that controls the engine based on voltage states of the first capacitor and the second capacitor;
The control unit discharges the second capacitor and maintains the charge state of the first capacitor when the condition for transitioning the engine to the automatic stop state is satisfied, and transitions to the automatic stop state . When the condition to be satisfied is not satisfied, the charging of the first capacitor is started after the charging of the second capacitor is started, and the voltage of the first capacitor is restarted when restarted from the low voltage reset. Is greater than or equal to the first voltage threshold and the voltage of the second capacitor is less than the second voltage threshold, the engine control determines that the state immediately before the low voltage reset is the automatic stop state apparatus.   The engine control device according to claim 1, wherein the controller starts charging the first capacitor when a predetermined standby time has elapsed after the charging of the second capacitor is started.   The engine according to claim 1, wherein the controller starts charging the first capacitor when the voltage of the second capacitor reaches a voltage threshold after starting charging of the second capacitor. Control device. A sum of an assumed value of the instantaneous power interruption time and an elapsed time until the control unit determines the control state of the engine based on the voltage state of the first capacitor and the second capacitor after power is restored The engine control device according to any one of claims 1 to 3, wherein the second time constant is longer than a value.

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