JP2002341067A - Electronic control device and off-period measurement method of power switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure a period wherein a power switch is kept off by a control part with a simple structure and without consuming much power, in an electronic control device. SOLUTION: In an ECU 1 having a control part such as a microcomputer 9 operated by feeding power from a battery 3 when an IGSW 7 is on, the microcomputer 9 clears an involatile counter and charges a capacitor 17 to a specified value by a charging circuit 21 when the IGSW 7 is on. While the IGSW 7 is off, an operation is repeated such that a voltage monitoring circuit 23 turns on a power feeding relay 5 every time the voltage Vc of the capacitor 17 drops to Vth (< the specified value), thereby the microcomputer 23 is operated to add one to the counter and turns off the relay 5 after charging the capacitor 17 to the specified value. When the IGSW 7 is turned on, the microcomputer 9 obtains the off period of the IGSW 7 from the counter value before the counter is cleared.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic control device having a control unit which operates by being supplied with power from a battery when a power switch is turned on, wherein the control unit turns off the power switch. The present invention relates to a technique for measuring time spent.

[0002]

2. Description of the Related Art Conventionally, for example, in an electronic control device for controlling an engine of an automobile, various electronic devices including a microcomputer (hereinafter referred to as a microcomputer) are mainly used as a control unit for performing various processes and operations for controlling the engine. A circuit (such as an A / D converter or a signal waveform shaping circuit) is provided, and its control unit operates such that power is supplied from a battery when an ignition switch as a power switch is turned on. Has become.

In recent years, in this type of electronic control device, the time during which the ignition switch is turned off (that is, the time during which substantial operating power is not supplied to the electronic control device, There is a demand that the control unit knows the off time.

For example, in the case of a heat storage system in which an object is heated by the cooling water of the engine, if the ignition switch is turned off, it means that the engine is stopped. By measuring the temperature of the engine, it is possible to predict how much the temperature of the cooling water of the engine, and consequently, the temperature of the object has dropped.

Therefore, as a method for measuring the power-off time by the control unit, for example, a time-measuring device provided with a clock for measuring the time when the ignition switch is off is provided inside or outside the electronic control device. Along with the provision, the power is always supplied from the battery to the timing device, and when the ignition switch is turned on and the control unit of the electronic control device starts operating, the control unit communicates the timing result from the timing device by communication. It is possible to receive it.

[0006]

However, in the above-described method, not only the clock device but also an auxiliary circuit for performing data communication between the clock device and the control unit is required. The hardware inside and outside will be greatly enlarged. Also, in the software executed by the control unit, communication software for acquiring data from the timing device increases, and as a result, the software becomes complicated.

[0007] Further, in order to construct a timepiece, an oscillation circuit for generating a clock is required, so that the power consumption becomes relatively large and the battery may run out. A method of measuring time using a clock is reliable in terms of accuracy and is suitable for measurement in units of one minute and one second, but when measurement accuracy is not so necessary (for example, 1
If measurement in units of hours or days is sufficient), an excessive system will result.

If the operating power is constantly supplied to the control unit, the off time of the ignition switch can be easily measured. However, in such a case, the power consumption of the battery when the ignition switch is turned off is reduced. In addition to the fact that becomes very large, the measurement of the power-off time, which is the time when the substantial operating power is not supplied to the electronic control device,
It deviates from the original purpose.

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and an electronic control device having a control unit that operates by being supplied with power from a battery when a power switch is turned on has a simple configuration and It is another object of the present invention to enable the control unit to measure the time during which the power switch is off without consuming a large amount of battery power.

[0010]

According to a first aspect of the present invention, there is provided a method of measuring an off time of a power switch, wherein power is supplied from a battery when the power switch is turned on. In an electronic control device having a control unit that operates in a controlled manner, the control unit measures the time during which the power switch is turned off.

In this off-time measuring method, (1): First, while the power switch is turned on, the control unit clears the value of the non-volatile counter and sets the capacitor to the value of the capacitor. The battery is charged so that the charging voltage becomes a predetermined specified value. In the following description, such charging is also referred to as “charging a capacitor to a specified value”.

(2) Next, from the time when the power switch is turned off to the time when the power switch is turned on next (that is, while the power switch is turned off), the charging voltage of the capacitor is maintained at the voltage. The following procedure is performed each time the voltage drops to a predetermined threshold value smaller than the specified value.

That is, when the charging voltage of the capacitor falls to the threshold value, first, power from the battery is supplied to the control unit, and the control unit causes the counter to count up and charge the capacitor. When the charging voltage of the capacitor reaches the specified value, the power supply to the control unit is stopped.

(3): When the power switch is turned on again, before the control unit clears the value of the counter, the control unit informs the control unit of the time during which the power switch was turned off based on the value of the counter. Is calculated. In other words, the value of the counter when the power switch is turned on represents the number of times the capacitor has been charged and discharged while the power switch is turned off, and the discharge voltage causes the charging voltage of the capacitor to exceed a specified value. The time required to decrease to a value (discharge time) Th and the time required for the charge voltage of the capacitor to rise from a threshold value to a specified value by charging (charge time) Tj are determined by the charge / discharge characteristics of the capacitor. Therefore, the approximate time during which the power switch has been turned off can be obtained from the value of the counter when the power switch is turned on. For example, assuming that the value of the counter when the power switch is turned on is N (where N is an integer of 1 or more), the time Tof when the power switch is turned off
f is changed from “Th + (N−1) × (Tj + Th)” to “T
h + N × (Tj + Th) ”.

According to the off-time measuring method of the first aspect, it is not necessary to constantly supply power to the control unit while the power switch is off, and the charging voltage of the capacitor is reduced to a specified value. Each time the voltage drops to the threshold value, power may be supplied to the control unit only while the capacitor is charged to the specified value. In addition, power must always be supplied only by means for detecting that the charging voltage of the capacitor has dropped to the threshold value and causing the control unit to supply power from the battery. Can be suppressed to be smaller than that of a circuit constituting a timepiece (for example, an oscillation circuit for generating a clock).

Further, according to the off-time measuring method of the first aspect, there is no need for a circuit for the controller to perform data communication with another device or complicated communication software. Therefore, according to this off-time measuring method, the control unit can measure the time during which the power switch is off with a simple configuration and without consuming a large amount of battery power.

The off-time measuring method according to claim 1 can be implemented by the electronic control device according to claim 3. That is, first, in addition to the control unit that is operated by supplying power from the battery when the power switch is turned on, the electronic control device according to claim 3 supplies the control unit with the power from the battery even when the power switch is turned off. , A capacitor that is charged by the control unit based on the power from the battery, and a capacitor voltage monitoring unit that monitors the charging voltage of the capacitor.

The driving means is switching means provided on a power supply line connecting a terminal of the electronic control unit and the battery for supplying electric power from the battery to the control unit. The power supply switching means for operating the control unit by connecting the line (that is, causing the control unit to supply power from the battery) is turned on in response to a drive command from the outside.

When the capacitor voltage monitoring means detects that the charging voltage of the capacitor has dropped to a predetermined threshold value, the capacitor voltage monitoring means outputs the drive command to the driving means, and the power supply switching means is connected to the driving means. Turn on. still,
When the power supply switching means is turned on, the power supply line is connected, so that the control unit operates by receiving power from the battery.

Further, in the electronic control device according to claim 3,
The control unit determines whether or not the control unit has been operated by turning on the power switch. If the determination is affirmative, the control unit determines that the capacitor has a predetermined charge voltage that is higher than the threshold value. The first charge control means for charging so as to have the prescribed value, and the operation of the capacitor voltage monitoring means instead of turning on the power switch to determine whether or not the control section has been operated. Outputting the drive command to the drive means, maintaining the ON state of the power supply switching means, counting up a non-volatile counter, and further charging the capacitor, and the charging voltage of the capacitor becomes the specified value. And a second charge control means for stopping the output of the drive command to the drive means and turning off the power supply switching means. Then, when the first charging control unit makes an affirmative determination, the control unit calculates the time during which the power switch is off based on the value of the counter, and then clears the value of the counter. It is configured.

In the electronic control device of the third aspect, when the power switch is turned on and the control unit operates, the first charging control means of the control unit operates the control unit by turning on the power switch. And the capacitor is charged to the specified value. Also, the control unit
If the first charge control means makes a positive determination, the value of the nonvolatile counter is cleared.

For this reason, the control unit clears the counter value and charges the capacitor to the specified value while the power switch is turned on. Is realized. Thereafter, when the power switch is turned off, the power supply to the control unit is stopped, and the capacitor is discharged.

When the charging voltage of the capacitor drops to the threshold value, the capacitor voltage monitoring means detects this, outputs a drive command to the drive means, and turns on the power supply switching means. . Then, the power supply line is connected, and the control unit operates by receiving power from the battery.

When the charging voltage of the capacitor drops to the threshold value and the control unit operates, the second charging control means of the control unit operates not by turning on the power switch but by the function of the capacitor voltage monitoring means. Makes a positive determination that the control unit has operated, and outputs a drive command to the drive unit to maintain the ON state of the power supply switching unit (that is, a state in which power is supplied from the battery to the control unit). At the same time, the counter is counted up, and the capacitor is charged. When the charged voltage of the capacitor reaches a specified value, the output of the drive command to the drive unit is stopped and the power supply switching unit is turned off.
Note that the power supply switching means is turned off when the output of the drive command by the second charge control means is stopped. At that time, the charging voltage of the capacitor has a specified value larger than the threshold value. This is because the output of the drive command from the capacitor voltage monitoring means to the driving means has already been completed.

Then, the power supply to the control unit is stopped, and the capacitor is discharged again. When it is detected by the capacitor voltage monitoring means that the charged voltage of the capacitor has dropped to the threshold value, the capacitor is again discharged. The above operation by the second charging control means of the control unit is performed.

For this reason, while the power switch is turned off, every time the charging voltage of the capacitor decreases to a threshold value smaller than the specified value, the power supply from the battery to the control unit is performed. However, the counter is counted up, the capacitor is charged, and when the charged voltage of the capacitor reaches the specified value, the power supply to the control unit is stopped. " The procedure of 2) is realized.

Then, when the power switch is turned on again from off, the first charge control means of the control section again determines that the control section has been operated by turning on the power switch, and sets the capacitor to the specified value. Charge. Further, when the first charging control unit makes an affirmative determination, the control unit clears the value of the counter as described above, but before the clearing, the power switch is reset based on the current value of the counter. The off-time Toff is calculated, and the operation (3) is realized by such an operation.

According to the electronic control device of the third aspect, it is not necessary to constantly supply power to the control unit while the power switch is turned off, and the charging voltage of the capacitor becomes a threshold value from a specified value. Each time the value is reduced to a value, power may be supplied to the control unit only while the capacitor is charged to the specified value. The only thing that must be constantly supplied is the capacitor voltage monitoring means for detecting that the charging voltage of the capacitor has dropped to the threshold value and causing the control unit to supply power from the battery. Since the capacitor voltage monitoring means can be constituted by a simple and power-saving circuit using a comparator, power consumption can be suppressed smaller than that of an oscillation circuit or the like constituting a timepiece. Further, according to this electronic control device, there is no need to add a circuit or complicated communication software for the control unit to perform data communication with another device. Therefore, according to the electronic control device of the third aspect, the off time T of the power switch can be reduced with a simple configuration and without consuming a large amount of battery power.
off can be measured by the control unit.

Further, according to the electronic control device of the third aspect, the control unit operates periodically during the period in which the power switch is turned off. Supplementary processing for improving the measurement accuracy of the off-time can also be performed. For example, when the control unit operates, the battery voltage and the degree of change in the charging voltage of the capacitor are detected, and based on the detected value,
By correcting the specified value, which is the charge target value of the capacitor, the above-described discharge time Th and charge time Tj are always constant, and the measurement accuracy of the off time can be improved.

Further, for example, the control section detects the degree of change of the battery voltage, the charging voltage of the capacitor, and the like, and
If it is determined based on the detected value that the charged amount of the battery is lower than the predetermined amount, the operation of measuring the off time thereafter is stopped to prevent the battery from running out. Is also good.

In this case, for example, when a power switch is turned on in a signal path for transmitting a drive command output from the capacitor voltage monitoring means to the drive means, the signal path continues even after the power switch is turned off. When a reset signal is received from the control unit when the power switch is turned off, a circuit that is in a reset state that cuts off the signal path is provided, and the control unit determines that the charged amount of the battery exceeds a predetermined amount. If it is determined that the power is also reduced, a reset signal may be output to the circuit so that power is not supplied to the control unit until the power switch is turned on.

In particular, in the off-time measuring method according to the first aspect or the electronic control apparatus according to the third aspect,
As described in above, when the power switch is an ignition switch of an automobile and the control unit controls an engine of the automobile, it is more important to suppress the power consumption when the ignition switch is turned off. However, also in this case, the control unit can measure the off time of the power switch without consuming a large amount of battery power, which is very effective.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electronic control unit according to an embodiment to which the present invention is applied will be described with reference to the drawings. First, FIG. 1 is a circuit diagram showing the electronic control device 1 of the first embodiment and wiring of a power supply system thereof.

An electronic control unit (hereinafter referred to as an ECU)
A main power supply terminal 1 controls an engine mounted on the vehicle, and is connected to a positive terminal of a battery 3 of the vehicle via a main relay 5 as a power supply switching means, as shown in FIG. J1 and battery 3
IGSW terminal J3 connected to a positive terminal of the battery 3 via an ignition switch (hereinafter referred to as IGSW) 7 as a power switch, and a positive terminal of the battery 3. And a main relay drive terminal J4 connected to the other end of the coil L of the main relay 5 having one end connected to the main relay 5.
In the present embodiment, the wiring H1 provided with the main relay 5 between the main power supply terminal J1 and the battery 3 corresponds to a power supply line.

The ECU 1 includes a microcomputer 9 for executing various processes for controlling the engine, and analog values such as various sensor signals (not shown) and a battery voltage (ie, a voltage of the battery 3) used for engine control. A / D converter 11 which converts a digital value into a digital value and inputs the digital value to the microcomputer 9 and a battery voltage (hereinafter referred to as VIG) input from the IGSW terminal J3 via the IGSW 7 From the input circuit 13 which converts the level into an IGSW signal and outputs the signal to the microcomputer 9, and the battery voltage (hereinafter referred to as V + B) input from the main power supply terminal J 1 via the main relay 5.
A main power supply voltage Vm for operating the / D converter 11 is generated and output, and a standby RAM incorporated in the microcomputer 9 is obtained from a battery voltage (hereinafter referred to as VBAT) constantly input from the sub power supply terminal J2. Includes a power supply circuit 15 that generates and outputs a sub power supply voltage Vs for constantly retaining data.

The power supply circuit 15 starts outputting the main power supply voltage Vm in response to the supply of V + B, and thereafter, the microcomputer 9 operates for a predetermined period of time when the main power supply voltage Vm is considered to be stable.
A so-called power-on reset function for outputting a reset signal to the power supply is also provided. Further, the input circuit 13 is composed of only electronic components that do not require a power supply.

Further, the ECU 1 is connected in parallel with the capacitor 17 that is charged and discharged to measure the time during which the IGSW 7 is turned off,
In accordance with a resistor (discharging resistor) 19 forming a discharge path of the capacitor 17 and a charge instruction signal output from the microcomputer 9 in a high active state, the capacitor 1 is determined based on V + B.
7 operates in response to the sub power supply voltage Vs constantly output from the power supply circuit 15 and monitors whether the charging voltage Vc of the capacitor 17 has dropped to a predetermined threshold voltage Vth. Then, when the charging voltage Vc becomes equal to or lower than the threshold voltage Vth, the capacitor voltage monitoring circuit 23 that outputs a high active discharge completion signal and VIG is supplied from the IGSW terminal J3 or the capacitor voltage monitoring circuit 23 When a charge / discharge completion signal is output or a high-active main relay drive signal is output from the microcomputer 9, a current flows through the coil L of the main relay 5 to turn on the main relay 5 (for details, And a main relay control circuit 25).

In the ECU 1 of this embodiment, V + B from the main power supply terminal J1 and the charging voltage Vc of the capacitor 17 are input to the A / D converter 11, and the microcomputer 9
Detects the values of these voltages via the A / D converter 11. Furthermore, the microcomputer 9 includes:
A discharge completion signal from the capacitor voltage monitoring circuit 23 is also input.

Here, the charging circuit 21 operates in response to V + B, and the operational amplifier OP1 in which the charging instruction signal from the microcomputer 9 is input to the non-inverting input terminal (+ terminal).
, And V + B to generate a reference voltage Vref lower than the voltage level (= main power supply voltage Vm) of the charging instruction signal, and input the reference voltage Vref to the inverting input terminal (−terminal) of the operational amplifier OP1. Two series voltage dividing resistors 31 and 33, a diode 35 having an anode connected to the output terminal of the operational amplifier OP1, one end connected to the cathode of the diode 35, and the other end opposite to the ground potential side of the capacitor 17. Resistor 37 connected to the side terminal
It is composed of

The charging circuit 2 configured as described above
In 1, when a charging instruction signal is output from the microcomputer 9 while receiving V + B from the main power supply terminal J1, a voltage based on V + B is output from the output terminal of the operational amplifier OP1. The capacitor 17 is charged via the diode 35 and the resistor 37.

The resistance value of the resistor 19 forming the discharge path of the capacitor 17 is set to a very large value (for example, several hundred KΩ) in order to discharge the capacitor 17 slowly. The resistance value of the resistor 37 is set to a value sufficiently smaller than that of the resistor 19 so that the capacitor 17 can be charged quickly. The diode 35 is provided to prevent a current from flowing backward from the capacitor 17 to the output terminal side of the operational amplifier OP1.

On the other hand, the capacitor voltage monitoring circuit 23
It operates by receiving the sub power supply voltage Vs from the power supply circuit 15 based on the BAT, and operates while charging the capacitor 17 with the charging voltage Vc.
Is input to the non-inverting input terminal.
And the sub power supply voltage Vs is divided to obtain the threshold voltage V
th, and the two series voltage dividing resistors 41 and 43 for inputting the threshold voltage Vth to the inverting input terminal of the comparator CMP1 and the output terminal of the comparator CMP1 and the auxiliary power supply voltage Vs. PNP in which the resistor 45 and the output terminal of the comparator CMP1 are connected to the base
It comprises a transistor 47 and a resistor 49 connected between the emitter of the transistor 47 and the auxiliary power supply voltage Vs. The resistor 45 is connected to the comparator CMP1
Since the output terminal is an open collector type capable of only drawing current, its output terminal is pulled up to the sub power supply voltage Vs so that a high level signal can be output from the comparator CMP1.

In the capacitor voltage monitoring circuit 23 thus configured, the charging voltage Vc of the capacitor 17 is
Is higher than the threshold voltage Vth, the comparator C
The output of MP1 goes high, turning off the PNP transistor 47. On the other hand, the capacitor 17
Is lower than the threshold voltage Vth, the output of the comparator CMP1 goes low and the PNP
The transistor 47 turns on. Then, the collector voltage of the PNP transistor 47 becomes high level (= sub power supply voltage Vs), and the collector voltage is output to the main relay control circuit 25 and the microcomputer 9 as a high level discharge completion signal.

The main relay control circuit 25 has an IG
The VIG from the SW terminal J3, the charge / discharge completion signal from the capacitor voltage monitoring circuit 23, and the main relay drive signal from the microcomputer 9 are wired-ORed by a diode or the like to the NPN transistor 51 supplied to the base. The collector of the NPN transistor 51 is connected to the main relay drive terminal J4.

In such a main relay control circuit 25, the IGSW 7 is turned on and the IGSW terminal J3 is connected to the VI
When G is supplied, a charge / discharge completion signal is output from the capacitor voltage monitoring circuit 23, or a main relay drive signal is output from the microcomputer 9, the NPN transistor 51
Is turned on, the transistor 51 draws current from the coil L of the main relay 5, and the main relay 5 is turned on accordingly.

When the main relay 5 is turned on, E
In the CU 1, electric power is supplied from the battery 3 to the microcomputer 9, the A / D converter 11, and the charging circuit 21, and these units 9, 11, and 21 operate. That is, the main power supply voltage Vm from the power supply circuit 15 based on V + B is supplied to each of the microcomputer 9 and the A / D converter 11, and V + B is directly supplied to the charging circuit 21. .

In the present embodiment, the microcomputer 9, the A / D converter 11, and the charging circuit 21 that operate based on V + B from the main power supply terminal J1 correspond to a control unit. The capacitor voltage monitoring circuit 23, which always operates based on the VBAT, corresponds to the capacitor voltage monitoring means. The main relay control circuit 25 corresponds to a driving unit, and the charge / discharge completion signal from the capacitor voltage monitoring circuit 23 and the main relay driving signal from the microcomputer 9 correspond to a driving command.

The ECU 1 having the hardware configuration as described above
Then, when the IGSW 7 is turned on and the main relay 5 is turned on by the action of the main relay control circuit 25, substantial operating power is supplied from the battery 3 via the main power supply terminal J1, and the microcomputer 9 and the A / D converter The control unit 11 and the like operate to control the engine.

Particularly, in the ECU 1 of the present embodiment,
The microcomputer 9 executes the off-time measuring process shown in FIG. 2 during operation, and the time during which the IGSW 7 is off (hereinafter simply referred to as “
Off time). Therefore, next, the contents of the off-time measurement processing executed by the microcomputer 9 will be described. The off-time measuring process is executed at regular intervals of several ms to several tens ms while the microcomputer 9 is operating.

As shown in FIG. 2, when the microcomputer 9 starts executing the off-time measuring process, first, in step (hereinafter simply referred to as "S") 110, it is determined whether or not the IGSW 7 is on. The determination is made based on the IGSW signal from the input circuit 13. If it is determined that the IGSW 7 is on (S110: YES), it is determined that the microcomputer 9 is operating because the IGSW 7 is turned on. S
After it is determined in step 110 that the IGSW 7 is in the on state, it is determined whether or not the off time of the IGSW 7 has already been measured.

If it is determined that the off time has not been measured (S120: NO), the process proceeds to S130, and the off time of the IGSW 7 is calculated based on the value of the trip counter incremented in S190 described later. .
The method of calculating the off-time will be described later with reference to FIG.

When the off time is calculated in S130, the value of the trip counter is cleared to 0 in the next S140, and thereafter, the off time measuring process is temporarily terminated. It should be noted that the trip counter is provided by the standby RAM in the microcomputer 9 (that is, the sub power supply voltage Vs from the power supply circuit 15).
This is a non-volatile counter set in a non-volatile RAM (Non-volatile RAM) that can always hold data in response to the request. The above S1
When the off-time is calculated at 30, the IGSW is performed at S110.
As long as it is continuously determined that 7 is in the on state, in S120 from the next time, the affirmative determination is made that the off time has been measured.

If it is determined in S120 that the off-time has been measured, the process proceeds to S150 to set the capacitor 17 to a voltage higher than the threshold voltage Vth compared by the capacitor voltage monitoring circuit 23. Predetermined prescribed value Vk
Charge until. That is, the microcomputer 9 controls the A / D converter 1
The charging instruction signal is output to the charging circuit 21 so that the charging voltage Vc of the capacitor 17 detected via the signal 1 becomes the specified value Vk, and the charging circuit 21 charges the capacitor 17. Then, after performing the process of S150, the process for measuring off time is temporarily terminated. Note that the above S150
By the above process, the charging voltage Vc of the capacitor 17 is maintained at the specified value Vk while the IGSW 7 is turned on.

On the other hand, if it is determined in step S110 that the IGSW 7 is not in the on state (ie, in the off state), the flow shifts to step S160, where the capacitor voltage monitoring circuit 2
Then, it is determined whether a discharge completion signal has been output from 3. Here, if the discharge completion signal has been output (S
160: YES), the microcomputer 9 is operated by the action of the capacitor voltage monitoring circuit 23 instead of turning on the IGSW 7 (that is, the charging voltage Vc of the capacitor 17 is reduced to the threshold voltage Vth by discharging, and the capacitor voltage monitoring circuit 23, the main relay 5 is turned on and the microcomputer 9 is operated by the output of the discharge completion signal to the main relay control circuit 25.
Proceed to.

In step S170, the main relay drive signal is output to the main relay control circuit 25, so that the main relay 5 is in the ON state and the substantial operating power is supplied from the battery 3 via the main power supply terminal J1. Is maintained. Then, in subsequent S180, it is determined whether or not the trip counter has been incremented. If not, the trip counter is not incremented (S18).
(0: NO), the process proceeds to S190, and the trip counter is incremented (one count up).

When the trip counter is incremented in S190, as long as it is continuously determined in S110 that the IGSW 7 is not on, in S180 from the next time, it is determined that the trip counter has been incremented. . Then, in step S190, the trip counter is incremented, or in step S1.
At 80, when it is determined that the trip counter has been incremented, the process proceeds to S200, where the capacitor 1
7, so that the charging voltage Vc returns to the specified value Vk.
A charging instruction signal is output to the charging circuit 21 to charge the capacitor 17.

Then, in S210, it is determined whether or not the charging voltage Vc of the capacitor 17 detected via the A / D converter 11 has reached the specified value Vk. If Vk has not been reached (S210: N
O) While the charging instruction signal to the charging circuit 21 is output, the off-time measurement process is temporarily ended.

In step S210, the capacitor 17
Is determined to have reached the specified value Vk, it is determined that the charging of the capacitor 17 has been completed, and S2
Proceeding to 20, the output of the main relay drive signal started in S170 is stopped. Then, at this time, the charge voltage Vc of the capacitor 17 is higher than the threshold voltage Vth, and the discharge completion signal as a drive command is no longer output from the capacitor voltage monitoring circuit 23 to the main relay control circuit 25. When the microcomputer 9 stops outputting the main relay drive signal, the main relay 5 is turned off, and the operation of each unit other than the capacitor voltage monitoring circuit 23 in the ECU 1 is stopped.

On the other hand, if it is determined in S160 that the discharge completion signal has not been output from the capacitor voltage monitoring circuit 23, the flow shifts to S230, where the capacitor 17
Is being charged (that is, the last time S20 is being charged).
0 is performed and a negative determination is made in S210).

Then, in S230, the capacitor 1
If it is determined that charging is being performed on S7, S2
The process proceeds to S00, and the processes of S200 and S210 are performed again. If it is determined in step S230 that the capacitor 17 is not being charged, the microcomputer 9
Is a state in which the main relay drive signal is being output for a purpose other than the purpose of measuring the off time of the IGSW 7, and in this case, the processing for measuring the off time is immediately finished, and another processing is performed.

That is, in the off-time measuring process, S
At 110, it is determined whether or not the IGSW 7 is turned on and the microcomputer 9, which forms the center of the control unit, has been operated. If the determination is affirmative (S110: YES), the charging instruction signal is output to the charging circuit 21 , The capacitor 17 is charged so that its charging voltage Vc becomes the specified value Vk (S1).
50).

Further, IG is performed by S110 and S160.
It is determined whether or not the microcomputer 9 has operated by the action of the capacitor voltage monitoring circuit 23 instead of turning on the SW7,
If an affirmative determination is made (S160: YES), first, a main relay drive signal is output to the main relay control circuit 25 to maintain the ON state of the main relay 5 (S17).
0), and increment the trip counter (S19).
0), and thereafter, the capacitor 17 is charged (S20).
0), when the charging voltage Vc reaches the specified value Vk (S210: YES), the output of the main relay drive signal is stopped, the main relay 5 is turned off, and the operating power is cut off (S220). ).

Further, in this off-time measuring process, when it is first determined that the microcomputer 9 has been operated by turning on the IGSW 7 in S110, the off-time of the IGSW 7 is calculated based on the value of the trip counter. Then, the value of the trip counter is cleared (S140).

In this embodiment, S1 in the microcomputer 9
The processes of S10 and S150 and the charging circuit 21 correspond to first charging control means in the control unit.
The processing of S110 and S160 to S220 in the above and the charging circuit 21 correspond to a second charging control unit in the control unit.

In the ECU 1 of the present embodiment as described above,
When the IGSW 7 is turned on, the main relay 5 is turned on, and the microcomputer 9, the A / D converter 11, and the charging circuit 21
Is operated by receiving the electric power from the battery 3. When the control unit is operated by turning on the IGSW 7, as shown in FIG.
7 is charged to the specified value Vk by the processing of S150 of the microcomputer 9 and the charging circuit 21, and the value of the nonvolatile trip counter is cleared to 0 by the processing of S140 of the microcomputer 9. Therefore, while the IGSW 7 is turned on, the charging voltage Vc of the capacitor 17 is maintained at the specified value Vk, and the value of the trip counter is initialized to zero.

Thereafter, as shown in FIG. 3, when the IGSW 7 is turned off from the on state, the main relay 5 is turned off and the power supply to the control unit is stopped.
Discharges through the resistor 19. And capacitor 1
7, the capacitor voltage monitoring circuit 23 detects that the charging voltage Vc has dropped to the threshold voltage Vth, and outputs a discharge completion signal as a drive command to the main relay control circuit 25 to control the main relay control. The circuit 25 turns on the main relay 5. Then, in FIG.
The control unit receives the power from the battery 3 and operates again, as indicated by the upward arrow indicating “start”.

When the control unit operates with the charging voltage Vc of the capacitor 17 lowered to the threshold voltage Vth in this way, the microcomputer 9 makes an affirmative determination in S160 and returns to S160.
By the process of 170, the microcomputer 9 outputs a main relay drive signal as a drive command to the main relay control circuit 25, whereby the main relay 5 is turned on (that is, power from the battery 3 is supplied to the control unit). State) is maintained. And further, S190 of the microcomputer 9
By the processing of, the trip counter is incremented (+
1) At the same time, the capacitor 17 is charged by the processing of S200 of the microcomputer 9 and the charging circuit 21, and when the charging voltage Vc of the capacitor 17 reaches the specified value Vk, the main relay control is performed by the processing of S220 of the microcomputer 9. The output of the main relay drive signal to the circuit 25 is stopped, and as a result, the main relay 5 is turned off and the ECU 1 is turned off, as shown by the downward arrow marked “ECU power off” in FIG.
Supply of operating power to the power supply is cut off. FIG.
In FIG. 5, the period during which the main relay 5 is turned on while the IGSW 7 is off and the operating power is supplied to the ECU 1 is indicated by oblique lines.

Then, the capacitor 17 is discharged again. When the capacitor voltage monitoring circuit 23 detects that the charged voltage Vc of the capacitor 17 has dropped to the threshold voltage Vth, the main relay 5 is turned on again. Then, the above operation is performed.

For this reason, while the IGSW 7 is turned off, the power from the battery 3 is supplied to the control unit every time the charging voltage Vc of the capacitor 17 decreases to the threshold voltage Vth smaller than the specified value Vk. Then, the control unit increases the value of the trip counter by 1 and charges the capacitor 17. When the charging voltage Vc of the capacitor 17 reaches the specified value Vk, power is supplied to the control unit (that is, the operating power of the ECU 1 is reduced). The operation of stopping the supply) and discharging the capacitor 17 is repeated.

When the IGSW 7 is turned on from the off state, the capacitor 17 is charged again to the specified value Vk by the processing of S150 of the microcomputer 9 and the charging circuit 21. Further, when the IGSW 7 is turned on, the microcomputer 9 clears the value of the trip counter to 0 by the processing of S140 in FIG. 2, but the microcomputer 9 executes the current trip in the processing of S130 immediately before the clearing. Based on the value of the counter, the off time Toff of the IGSW 7 is calculated as follows.

First, the value of the trip counter when the IGSW 7 is turned on represents the number of times the capacitor 17 has been charged and discharged as shown in FIG. 3 while the IGSW 7 has been turned off. The time (discharge time) Th required for the charging voltage Vc to decrease from the specified value Vk to the threshold voltage Vth,
7 from the threshold voltage Vth to the specified value Vk
The time (charge time) Tj required to increase the charge / discharge characteristics of the capacitor 17 (specifically, the capacitor 1
7, each element constant of the discharging resistor 19 and the charging circuit 21)
Since it is a known value determined by the IGSW 7, the approximate time during which the IGSW 7 has been turned off can be obtained from the value of the trip counter when the IGSW 7 is turned on.

Then, if the value of the trip counter is N (where N is an integer of 1 or more) in S130 of FIG. 2, the microcomputer 9 sets the off time Tof of the IGSW 7 to OFF.
f from “Th + (N−1) × (Tj + Th)” to “T
h + N × (Tj + Th) ”.

According to the ECU 1 of the present embodiment as described above, it is not necessary to constantly supply power to the control unit during the period in which the IGSW 7 is turned off, and the charging voltage Vc of the capacitor 17 is reduced from the specified value Vk. Every time the voltage drops to the threshold voltage Vth, power may be supplied to the control unit only while the capacitor 17 is charged to the specified value Vk. Further, only the capacitor voltage monitoring circuit 23 for detecting that the charging voltage Vc of the capacitor 17 has dropped to the threshold voltage Vth and turning on the main relay 5 only needs to constantly supply power, Since the capacitor voltage monitoring circuit 23 is a simple and power-saving circuit using the comparator CMP1, the power consumption can be suppressed smaller than that of an oscillation circuit or the like forming a timepiece. And further
According to the ECU 1, there is no need to add a circuit or complicated communication software for the control unit to perform data communication with another device.

Therefore, according to the ECU 1 of the present embodiment,
The off-time of the IGSW 7 can be measured by the control unit with a simple configuration and without greatly consuming the power of the battery 3. In particular, when the IGSW 7 is turned off, the engine stops and the battery 3 is not charged, so it is important to keep the power consumption of the battery 3 low.
The configuration and method of U1 are effective.

On the other hand, the configuration and method of the ECU 1 of the present embodiment are added to a system for measuring the off-time of the IGSW 7 with a high accuracy by a timer provided with a clock different from the ECU 1, and the timer is operated normally. It can also be used for diagnosis for determining whether or not it is operating.

Further, according to the ECU 1 of the present embodiment, while the IGSW 7 is turned off, the microcomputer 9 forming the center of the control unit operates periodically. Supplementary processing for improving the measurement accuracy of the off time of the IGSW 7 can also be performed.

For example, each time the microcomputer 9 operates during the off period of the IGSW 7, the degree of change of the charging voltage Vc of the capacitor 17 via the A / D converter 11 (that is,
By detecting at least one of the change degree of Vc during charging) and the battery voltage, and correcting the specified value Vk as the charging target value of the capacitor 17 based on the detection result, the discharge time Th and the discharge time Charging time Tj
Is always constant, the measurement accuracy of the off-time can be improved.

Further, for example, every time the microcomputer 9 operates during the off period of the IGSW 7, the above detection result (the change degree of the battery voltage or the charging voltage Vc of the capacitor 17) is obtained.
It is determined whether the charged amount of the battery 3 is lower than the predetermined amount based on the following formula, and if it is determined that the charged amount of the battery 3 is lower than the predetermined amount, The measurement operation may be stopped to surely prevent the battery from running out.

In this case, for example, as shown in FIG. 4, a signal path K for transmitting the discharge completion signal output from the capacitor voltage monitoring circuit 23 to the main relay control circuit 25 is
When the IGSW 7 is turned on, a set state is established in which the signal path K is continuously communicated even after the IGSW 7 is turned off. When a reset signal from the microcomputer 9 is received when the IGSW 7 is turned off, a reset that cuts off the signal path K is performed. When the microcomputer 9 determines that the charged amount of the battery 3 is lower than the predetermined amount, the microcomputer 9 outputs a reset signal to the switching circuit 61, and thereafter the IGSW 7 is turned on. Until the main relay 5 is turned on (that is, power is not supplied to the control unit including the microcomputer 9).

The switching circuit 61 operates upon receiving, for example, the sub power supply voltage Vs from the power supply circuit 15, and receives the IGSW signal from the input circuit 13 to the set terminal (S). Latch circuit 63 in which the reset signal is input to reset terminal (R)
The signal path K is connected to the signal path K when the output of the latch circuit 63 is at a high level (when the latch circuit 63 is in a set state) and when the output of the latch circuit 63 is at a low level ( (When the latch circuit 63 is in the reset state)
And a buffer circuit 65 that cuts off the signal path K.

Next, an ECU according to a second embodiment will be described with reference to FIG. Note that, in FIG. 5, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. As shown in FIG. 5, the ECU 2 of the second embodiment
Is different from the ECU 1 of the first embodiment only in the following points (A) and (B).

(A): The main relay control circuit 25
VIG is not input from the GSW terminal J3. Therefore, when the charge / discharge completion signal is output from the capacitor voltage monitoring circuit 23 or the main relay drive signal is output from the microcomputer 9, the main relay control circuit 25 applies a current to the coil L of the main relay 5. The main relay 5 is turned on.

(B): Instead, IGSW terminal J3
And V + B from the main power supply terminal J1 are wired-ORed by the diodes D1 and D2 and supplied to the power supply circuit 15 and the charging circuit 21. Then, the power supply circuit 15 generates the main power supply voltage Vm from the wired-OR voltage (ie, VIG or V + B), and
Operate at the wired-OR voltage.

That is, in the ECU 2 of the second embodiment, I
When the GSW 7 is turned on, operating power is supplied from the IGSW terminal J3. And such a second
The ECU 2 of the first embodiment is also used by the ECU 2 of the first embodiment.
1 operates in exactly the same way as the ECU 1, and the same effects as those of the ECU 1 are obtained.

The structure of the second embodiment can be similarly applied to the modification of the first embodiment shown in FIG. As mentioned above, although one Embodiment of this invention was described, it cannot be overemphasized that this invention can take various forms.

For example, in each of the above embodiments, a data rewritable nonvolatile ROM such as a flash ROM or an EEPROM may be used as the memory for the trip counter instead of the standby RAM. Although the ECU of each of the above embodiments uses the IGSW of the vehicle as a power switch, the present invention also relates to an electronic control device that uses a switch other than the IGSW as a power switch.
Exactly the same can be applied.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating an electronic control device according to a first embodiment and wiring of a power supply system thereof.

FIG. 2 is a flowchart showing off-time measurement processing executed by a microcomputer of the electronic control unit.

FIG. 3 is a time chart illustrating an operation of the electronic control device according to the first embodiment.

FIG. 4 is a circuit diagram illustrating an electronic control device of a modified example and wiring of a power supply system thereof.

FIG. 5 is a circuit diagram illustrating an electronic control device according to a second embodiment and wiring of a power supply system thereof.

[Explanation of symbols]

1, 2,... Electronic control unit (ECU), 3,.
Main relay, 7 ... Ignition switch (IGS
W), 9: microcomputer, 11: A / D converter, 13: input circuit, 15: power supply circuit, 17: capacitor, 21: charging circuit, 23: capacitor voltage monitoring circuit, 25: main relay control circuit, 19, 31, 33, 37, 41, 43,
45, 49: resistor, 35, D1, D2: diode, O
P1: operational amplifier, CMP1: comparator, 47: P
NP transistor, 51 ... NPN transistor, 61 ...
Switching circuit, 63 latch circuit, 65 buffer circuit, H1 wiring as power supply line, J1 main power terminal, J2 auxiliary power terminal, J3 IGSW terminal, J4 main relay drive terminal

Claims (4)

[Claims] An electronic control device having a control unit that operates by being supplied with power from a battery when a power switch is turned on, wherein the control unit measures the time that the power switch is turned off. A method for measuring an off time of a power switch, wherein the control unit clears a value of a non-volatile counter while the power switch is turned on, and sets a capacitor to a predetermined charging voltage. In the period from when the power switch is turned off to when the power switch is next turned on, the charging voltage of the capacitor is reduced to a predetermined threshold value smaller than the specified value. Each time the voltage drops, the controller supplies power from the battery to the controller, causing the controller to count up the counter, When the charging voltage of the capacitor reaches the specified value, the power supply to the control unit is stopped.When the power switch is turned on again, the control unit changes the value of the counter. Before the clearing, the control unit calculates the time during which the power switch has been turned off based on the value of the counter. 2. The method of measuring the off time of a power switch according to claim 1, wherein the power switch is an ignition switch of a vehicle, and the control unit controls an engine of the vehicle. Characteristic power switch off time measurement method. 3. An electronic control device having a control unit that operates by being supplied with electric power from a battery when a power switch is turned on, wherein the electronic control unit supplies electric power from the battery to the control unit. A drive unit that is provided on a power supply line that connects a terminal of a control device and the battery and that turns on the power supply switching unit that operates the control unit by connecting the power supply line by turning on the power supply unit; When the control unit detects that the capacitor is charged based on the power from the battery and that the charged voltage of the capacitor has decreased to a predetermined threshold, the control unit outputs the drive command to the drive unit, The driving means further includes a capacitor voltage monitoring means for turning on the power supply switching means, and the control unit further comprises: As a result, it is determined whether or not the control unit has been operated. If the determination is affirmative, the capacitor is charged so that the charging voltage of the capacitor becomes a predetermined specified value larger than the threshold value. A first charge control unit, and determining whether or not the control unit has been operated by the action of the capacitor voltage monitoring unit instead of turning on the power switch, and if the determination is affirmative, the drive command is transmitted to the drive unit. To maintain the ON state of the power supply switching means, count up a non-volatile counter, further charge the capacitor, and when the charged voltage of the capacitor reaches the specified value, drive the drive. Second charging control means for stopping the output of the drive command to the power supply means and turning off the power supply switching means, and the first charging control means. When the determination is affirmative, the electronic control unit is configured to calculate the time during which the power switch is turned off based on the value of the counter, and then clear the value of the counter. apparatus. 4. The electronic control device according to claim 3, wherein the power switch is an ignition switch of an automobile, and the control unit controls an engine of the automobile. Control device.