WO2016084446A1

WO2016084446A1 - Engine control device

Info

Publication number: WO2016084446A1
Application number: PCT/JP2015/074650
Authority: WO
Inventors: 泰敏平野; 貴矩敬寛; 英斗塚越; 豊秋元
Original assignee: 株式会社ケーヒン
Priority date: 2014-11-25
Filing date: 2015-08-31
Publication date: 2016-06-02
Also published as: JP2016098752A; JP6530597B2

Abstract

The present invention provides an engine control device that controls an engine of a vehicle, having: an instantaneous-interruption determining circuit; a holding circuit; and a control unit. The instantaneous-interruption determining circuit includes a first capacitor and a first resistor that discharges and charges the first capacitor at a first time constant. The holding circuit includes a second capacitor and a second resistor that discharges and charges the second capacitor at a second time constant equal to or larger than the first time constant. The control unit controls the engine on the basis of the voltage states of the first capacitor and the second capacitor. Furthermore, the control unit starts to charge the first capacitor after starting to charge the second capacitor. Even if the control unit of the engine control device is reset due to a temporary reduction in battery voltage, information indicating the engine control state immediately before the reset can be held.

Description

Engine control device

The present invention relates to an engine control device.

In order to reduce exhaust gas and reduce fuel consumption, a vehicle that automatically stops the engine when a predetermined engine stop condition is established by waiting for a signal or the like has been put into practical use. If the accelerator is operated in the automatic stop state, the engine is automatically restarted.

If the vehicle is equipped with an automatic engine stop function and a firelight such as a headlamp is used while the engine is automatically stopped, there is a concern that the amount of power stored in the battery may drop rapidly. There has been proposed a technique for automatically dimming or extinguishing a fire when the automatic stop state of the engine continues for a predetermined time or longer (see Patent Document 1).

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

JP 2004-108191 A

Since the battery of saddle-ride type vehicles has a smaller capacity than the battery of a four-wheeled vehicle, the amount of stored electricity tends to decrease due to the use of a fire when the engine is stopped. When the starter motor is driven for the automatic restart of the engine in a state where the amount of stored electricity 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 is recovered and the CPU is restarted, whether the engine control state at the time of CPU reset was an automatic stop state or not an automatic stop state in order to perform appropriate engine control Is preferably determined.

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

However, when the number of times the flag information is rewritten approaches the upper limit of the number of times that the nonvolatile memory can be rewritten, the reliability of the flag information decreases. Furthermore, when the number of rewrites of the flag information exceeds the upper limit of the number of times that the nonvolatile memory can be rewritten, it may become impossible to rewrite.

An object of the present invention is to provide an engine control device capable of holding information indicating the control state of the engine immediately before the reset even when the control unit of the engine control device 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 provides:
An engine control device for controlling a vehicle engine,
An instantaneous interruption determination circuit including a first capacitor and a first resistor that charges and discharges 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 equal to or greater than the first time constant;
A controller that controls the engine based on voltage states of the first capacitor and the second capacitor;
The controller starts charging the first capacitor after starting charging the second capacitor.

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 has elapsed after starting charging the second capacitor.

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

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,
Sum of an assumed value of 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 the power is restored The second time constant is longer than the value.

In the engine control apparatus according to the first aspect, for example, when a condition for transitioning the engine to a predetermined control state is satisfied, discharging of the second capacitor is started and the charged state is maintained for the first capacitor. To do. When the control unit is reset due to a temporary voltage drop (power supply interruption), the control state of the engine immediately before the voltage drops is controlled by detecting the charge / discharge state of the second capacitor. It can be determined whether or not it was in a state. Whether the reset is caused by a momentary power interruption or a normal power activation can be determined by the charge / discharge state of the first capacitor.

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

If a power supply interruption occurs during a period when the second capacitor is not sufficiently charged, the condition for transitioning to the predetermined control state even though the condition for transitioning the engine to the predetermined control state is not satisfied Will be erroneously determined to be satisfied. In the engine control apparatus according to the first aspect, since it is difficult to generate a period in which the second capacitor is not sufficiently charged, 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 erroneous determination.

In the engine control apparatus according to the fourth aspect, the state of charge of the second capacitor can be substantially maintained until the voltage state of the second capacitor is determined after the power is turned off. For this reason, it is possible to determine the control state of the engine based on the voltage state of the second capacitor at the time of power-off.

FIG. 1A is a block diagram and an equivalent circuit diagram of an engine control device according to the embodiment, and FIG. 1B is an equivalent circuit diagram of a momentary interruption determination circuit and a holding circuit of the engine control device according to a modification of the embodiment. FIG. 2 is a graph showing an example of a time change of the power supply voltage, the voltage of the first capacitor of the instantaneous interruption determination circuit, and the voltage of the second capacitor of the holding circuit. FIG. 3A is a chart showing the relationship between the voltages of the first capacitor and the second capacitor after the reset 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 reset of a part. FIG. 4 is a graph showing an example of a time change of the power supply voltage, the voltage of the first capacitor of the instantaneous interruption determination circuit, and the voltage of the second capacitor of the holding circuit in the engine control apparatus according to the comparative example.

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

The instantaneous interruption determination circuit 11 is configured by 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. The first capacitor C1 is charged / discharged 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. For this reason, 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 with the first time constant via the first resistor R1. When the first output port 13A is pulled down to the ground voltage, the first capacitor C1 is discharged through the first resistor R1 with the first time constant.

The holding circuit 12 is composed 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. For this reason, 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 with the second time constant via the second resistor R2. When the second output port 13C is pulled down to the ground voltage, the second capacitor C2 is discharged through the second resistor R2 with the second time constant. The second time constant is longer than the first time constant.

Information such as the vehicle speed, cooling water temperature, engine speed, automatic stop control selection switch, ignition key, etc. of the vehicle on which the engine control device 10 is mounted is input to the engine control device 10. The automatic stop control selection switch is used by the driver to select whether to enable or disable the engine automatic stop function. 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 larger than the resistance values of the first resistor R1 and the second resistor R2, and are substantially infinite. Can think. The output impedances of the first output port 13A and the second output port 13C of the control unit 13 are considered to be substantially zero compared to the resistance values of the first resistor R1 and the second resistor R2 and substantially zero. be able to.

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

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

In 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 where 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 or not the engine automatic stop condition 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, first, the control unit 13 (FIG. 1A) starts to charge the second capacitor C2 by pulling up the second output port 13C to the voltage Vdd. As a result, the second voltage V2 increases toward the voltage Vdd with the second time constant. After starting the charging of the second capacitor C2, at time t2, the control unit 13 starts to charge the first capacitor C1 by pulling up the first output port 13A to the voltage Vdd. As a result, the first voltage V1 increases toward the voltage Vdd with the first time constant. Since the second time constant is longer than the first time constant, the rising slope of the second voltage V2 is more gradual than the rising slope of the first voltage V1.

An example in which the power supply is momentarily interrupted during the period from time t3 to time t4 will be described. When the power is cut 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 with the first time constant. Further, the second capacitor C2 is discharged, and the second voltage V2 decreases with the 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. For this reason, 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 activated at time t4, the control unit 13 controls the first voltage V1 and the first voltage of the first capacitor C1 at time t5 as in the case of time t1. The second voltage V2 of the second capacitor C2 is read. Since the instantaneous power interruption time is short, the first voltage V1 does not decrease to the first voltage threshold Vt1, and the second voltage V2 does not decrease 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 instantaneous power interruption time. As an example, the second voltage threshold value Vt2 is the same as the first voltage threshold value Vt1, and is ½ of the voltage Vdd.

If the first output port 13A and the second output port 13C (FIG. 1A) remain pulled down to the ground voltage after the power supply is recovered at time t4, the first capacitor C1 and the second capacitor until the time t5. The discharge of the second capacitor C2 is continued. In this case, the assumed value of the instantaneous power interruption time and the elapsed time from when the power is restored until the control unit 13 determines the engine control state 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 (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) indicates that the engine is in a non-automatic stop state. It is determined that a power interruption has occurred. When the state of the engine before the instantaneous interruption is a non-automatic stop state, the control unit 13 starts charging the second capacitor C2 and then charges the first capacitor C1 in the same manner as at time t1. Start. During the period up to 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 engine automatic stop condition is satisfied and the engine automatically stops at time t6. When determining that the engine automatic stop condition is satisfied at time t6, the control unit 13 (FIG. 1A) discharges the second capacitor C2 by pulling down the second output port 13C to the ground voltage. The charged state is maintained for the first capacitor C1. When a time sufficiently longer than the time constant of discharge of the second capacitor C2 (second time constant) has elapsed, the second voltage V2 becomes approximately 0V.

FIG. 2 shows an example in which the power supply is momentarily interrupted during a period from time t7 to time t8 when the second voltage V2 is substantially 0V. At time t7, the second voltage V2 is less than the second voltage threshold Vt2. When the power supply is cut off at time t7, the first capacitor C1 is discharged, and the first voltage V1 decreases with the first time constant. At time t8 when the power supply recovers, 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 the 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. V1 and the second voltage V2 of the second capacitor C2 are read. Since the power supply interruption time is short, the first voltage V1 does not decrease to the first voltage threshold value Vt1. The second voltage V2 is 0V.

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

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

When the time from when the power supply to the control unit 13 is shut off until the power supply recovers is sufficiently longer than the first time constant, the first power supply recovery point (for example, time t0 in FIG. 2) The voltage V1 of 1 has decreased to less than the first voltage threshold Vt1. In this case, it is determined that the control unit 13 has been reset by a factor other than a momentary power interruption, specifically, by turning on the ignition key.

In the reset process of the control unit 13, when it is determined that the first voltage V1 is equal to or higher than the voltage threshold, it is determined that the control unit 13 is reset due to a momentary power interruption. If the engine is in the automatic stop state when the instantaneous power interruption occurs, 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 value Vt1 and the second voltage V2 is lower than the second voltage threshold value 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 at the time of the momentary power interruption (the non-automatic stop state), the second voltage V2 is set to the second voltage threshold as in the voltage state at time t3 in FIG. 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 power It is determined that a disconnection has occurred.

FIG. 3B shows a flowchart of processing executed by the control unit 13 when the control unit 13 (FIG. 1A) is reset. When the control unit 13 is reset due to ignition switch-on, power supply interruption, etc., in step S1, the first voltage V1 of the first capacitor C1 is read from the first input port 13B (FIG. 1A), and The second voltage V2 of the second capacitor C2 is read from the second input port 13D. Resetting the control unit 13 due to a decrease in power supply voltage is referred to as “low voltage reset”.

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

If it is determined in step S2 that the first voltage V1 is equal to or higher than the first voltage threshold Vt1, the second voltage V2 of the second capacitor C2 is equal to or higher than the second voltage threshold Vt2 in step S3. 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 that an instantaneous power supply interruption occurred as shown in FIG. 3A.

If it is determined in step S3 that the second voltage V2 is equal to or greater than the second voltage threshold Vt2, it is determined in step S4 that the engine is not in the automatic stop state when the power is momentarily interrupted. 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 an automatic stop state at the time of instantaneous power interruption. This determination result corresponds to the determination result at time t9 in FIG.

In any of steps S4 to S6, when the cause of the low voltage reset of the control unit 13 is specified, it is determined in step S7 whether or not an automatic engine stop condition is satisfied. This determination is made 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 has already been pulled down to the ground voltage, the second capacitor C2 is continuously discharged by maintaining the pull-down state. The charged state is maintained for the first capacitor C1. Step S8 corresponds to the processing executed in the period from time t6 to 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 thereafter charging of the first capacitor C1 is started. The charging start of the second capacitor C2 corresponds to the process at time t1 in FIG. 2, and the charging start of the first capacitor C1 corresponds to the process at time t2 in FIG. If the charging of the second capacitor C2 has already started, the 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 started, the 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 momentary power interruption is stored by the electric charge accumulated in the second capacitor C2. For this reason, it is not necessary to use a non-volatile memory for storing the engine control state. Thereby, it is possible to avoid a decrease in reliability caused by the number of times of rewriting of the nonvolatile memory approaching the upper limit value of the number of times of rewriting. Further, there is no need to perform maintenance work such as replacement of the nonvolatile memory.

Next, the effect of making the second time constant of charging / discharging of the second capacitor C2 longer than the first time constant of charging / discharging of the first capacitor C1 will be described. When the second time constant is shorter than the first time constant, the second voltage V2 may become less than the second voltage threshold Vt2 at time t4 shown in FIG. When the second voltage V2 becomes less than the second voltage threshold Vt2 at time t4, it is erroneously determined that the engine was automatically stopped even though the engine was not automatically stopped when the instantaneous power interruption occurred. End up. 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 value Vt1 and the second voltage threshold value 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 equal to or higher than the threshold value Vt1, the second voltage V2 is also equal to or higher than the second voltage threshold value Vt2. Therefore, theoretically, the first time constant and the second time constant may be equal. However, if 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 are equal, due to manufacturing variations of capacitors and resistors. The second time constant may be shorter than the first time constant.

When the circuit constants of the instantaneous interruption determination circuit 11 and the holding circuit 12 (FIG. 1A) are designed so that the second time constant is longer than the first time constant, the component constants of the capacitor and the resistor vary within an allowable range. Even if there is, an event in which the second time constant is shorter than the first time constant is unlikely to occur. Therefore, an erroneous determination is unlikely to occur in determining whether or not the engine has been automatically stopped. In order to avoid misjudgment, when considering variations in the component constants of the capacitor and the resistor, the lower limit value within the variation range of the second time constant is within the variation range of the first time constant. 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 the first capacitor C1 after starting charging 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 started simultaneously. 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 started simultaneously. 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. A case where a power interruption 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 at or above the first voltage threshold Vt1 even at time t13 when the power supply recovers. 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 is erroneously determined that the engine was in the automatic stop state when the instantaneous power interruption occurred.

In the embodiment shown in FIG. 2, charging of the first capacitor C1 is started at time t2 when a certain elapsed time has elapsed from time t1 when charging of the second capacitor C2 was started. Therefore, the period in which the first voltage V1 is equal to or higher than the first voltage threshold Vt1 and the second voltage V2 is less than the second voltage threshold Vt2 is shorter than that in the example of FIG. No longer exists. 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 value 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 less than the second voltage threshold Vt2 does not occur.

The first time constant and the second time constant are set as a standby time (time from time t1 to t2) from the start of charging of the second capacitor C2 to the start of charging of the first capacitor C1. Based on this, it is possible to set a fixed value in advance. As an example, it is preferable that the standby time is longer than the time until the second voltage V2 reaches the second voltage threshold Vt2.

If the standby time is too long, the time from the time t0 until the first voltage V1 reaches the first voltage threshold value Vt1 becomes long. If the engine is automatically stopped during the period from time t0 until the first voltage V1 reaches the first voltage threshold value Vt1, and the power supply is interrupted at the time of restart, the engine is 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 automatically stops 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 at an early stage. As an example, after the ignition key is turned on, the engine is automatically stopped for the first time and the discharge of the second capacitor C2 is started until the second voltage V2 becomes equal to or lower than the second voltage threshold Vt2. If the voltage V1 is equal to or higher than the first voltage threshold value Vt1, the automatic stop state can be accurately determined by the reset process after the instantaneous power interruption.

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

FIG. 1B shows a block diagram and an equivalent circuit diagram of an engine control apparatus 10 according to a modification of the embodiment. In this modification, the connection 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 cut 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. Will be affected. The third resistor R3 has a function of maintaining a high effective input impedance when the first input port 13B is viewed from the interconnection point between the first capacitor C1 and the first resistor R1. Similarly, the fourth resistor R4 maintains a high effective input impedance when the second input port 13D is viewed from the interconnection 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 cut off, as shown in FIG. An interconnection point between the capacitor C1 and the first resistor R1 may be directly connected to the first input port 13B. Similarly, an interconnection 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 with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

DESCRIPTION OF SYMBOLS 10 Engine control apparatus 11 Instantaneous interruption determination circuit 12 Holding circuit 13 Control apparatus 13A 1st output port 13B 1st input port 13C 2nd output port 13D 2nd input port 20 Starter 21 Engine C1 1st capacitor C2 1st Second capacitor R1 First resistor R2 Second resistor R3 Third resistor R4 Fourth resistor V1 First voltage V2 Second voltage Vt1 First voltage threshold Vt2 Second voltage threshold

Claims

An engine control device for controlling a vehicle engine,
An instantaneous interruption determination circuit including a first capacitor and a first resistor that charges and discharges 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 controller that controls the engine based on voltage states of the first capacitor and the second capacitor;
The control unit is an engine control device that starts charging the first capacitor after starting charging the second capacitor.
The engine control device according to claim 1, wherein the control unit starts charging the first capacitor when a predetermined standby time has elapsed after starting charging the second capacitor.
2. 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. 3. Control device.
Sum of an assumed value of 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 the power is restored The engine control apparatus according to any one of claims 1 to 3, wherein the second time constant is longer than a value.