JP2009075725A - Electronic controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately determine that a high state of an input signal changes to a low state when an external power supply voltage is lowered, in an electronic controller having a function of boosting the external power supply voltage via a boosting circuit to generate an operating voltage for a microcomputer. <P>SOLUTION: In an on-board electronic controller having a function of boosting a battery voltage (hereinafter referred to as VB) to generate the operating voltage of the microcomputer, a switch signal, which is set at VB as a high state when the switch is turned on and is set at a ground voltage as a low state when the switch is turned off, is used as an input signal. Then, the microcomputer detects the input signal and VB with a built-in A/D converter (S210, S220), and sets a threshold value Y for determining that the input signal changes from "high" to "low" to be a lower value as a detection value becomes lower according to the detection value of VB (S270). Additionally, the microcomputer, when determining that the detection value of the input signal≤the threshold value Y, takes the determination result of the input signal as "low" (S280). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electronic control device including a booster circuit for generating a microcomputer operating voltage from an external power supply voltage.

  2. Description of the Related Art Conventionally, an in-vehicle electronic control device having a booster circuit so as to be operable even when a battery voltage as an external power supply voltage is lowered is known, and engine start control is performed by such an electronic control device. This has also been proposed (see, for example, Patent Document 1).

  And this kind of electronic control unit is equipped with the microcomputer which performs control processing, and if the battery voltage is higher than the specified value, the operating voltage of the microcomputer is generated from the battery voltage, and the battery voltage is below the specified value. In this case, the operation voltage of the microcomputer is generated from the voltage obtained by boosting the battery voltage by the booster circuit.

Patent Document 2 describes that when a power supply voltage drops below a reference voltage, a signal input to a microcomputer is invalidated.
JP 2006-118481 A Japanese Patent No. 2527518

  According to the electronic control device including the booster circuit as described above, the minimum value of the operable battery voltage can be lowered, but when the battery voltage drops, the microcomputer erroneously inputs the input signal from the input port. There is a possibility of judging.

  For example, as shown in FIG. 11, when a switch is turned on, the battery voltage is set to a high state, and when the switch is turned off, a high active switch signal that is set to a low state and a ground voltage (= 0V) is an input signal. An example will be described. That is, the input signal of FIG. 11 is a voltage of a signal line that is pulled down to the ground voltage via the resistance component and connected to the battery voltage via the switch.

With this input signal, when the battery voltage decreases when the switch is turned on and in the high state, the voltage of the input signal also decreases.
On the other hand, even if the battery voltage drops, the microcomputer is supplied with a constant operating voltage by the action of the booster circuit, so that the threshold voltage for determining high / low is constant at the input port of the microcomputer. is there.

  For this reason, when the voltage of the input signal decreases due to a decrease in the battery voltage, the microcomputer is actually in the high state with the switch on, but the microcomputer has the input signal in the low state as shown by the solid line in the lowermost stage of FIG. It is erroneously determined that the switch is off.

As a result, the control process based on the input signal cannot be performed correctly due to a decrease in the battery voltage, even though the electronic control apparatus includes the booster circuit.
This problem is not limited to a high-active switch signal. When the switch is turned on, the low voltage is set to the ground voltage (= 0 V). When the switch is turned off, the voltage is set to the battery voltage or a voltage proportional to the battery voltage. The same applies to the active switch signal. That is, in the case of a low-active switch signal, it is erroneously determined that the switch is on even though the switch is actually off.

  In order to prevent the erroneous determination described above, if the idea of Patent Document 2 is used, as shown by the dotted line in the lowermost stage of FIG. 11, if the battery voltage becomes lower than the predetermined hold determination voltage, It can be considered that the high / low judgment result (switch on / off judgment result) of the input signal up to the above is held without being changed.

  However, with such a configuration, another problem arises that this time it is impossible to detect a change in the state of the input signal. For example, in the engine start control, the starter is driven on condition that the brake signal whose state changes in the same manner as the input signal in FIG. 11 by turning on / off the brake switch is in a high state indicating depression of the brake pedal. It is supposed to be. In this example, the brake switch is a switch that is turned on when the brake pedal is depressed. However, if such a high / low judgment result of the brake signal is held when the battery voltage decreases, even if the brake switch is turned off when the battery voltage decreases due to the starter driving, the brake The determination result of the signal remains high, and this cannot be detected and the drive of the starter is continued.

  The present invention has been made in view of these problems, and in an electronic control device having a function of generating an operating voltage of a microcomputer by boosting an external power supply voltage by a booster circuit, when the external power supply voltage is lowered, The purpose is to make it possible to accurately determine that the signal has changed from a high state to a low state.

  In the electronic control device according to claim 1, when the external power supply voltage supplied from the outside is higher than the specified value, the operating voltage of the microcomputer is generated from the external power supply voltage, and the external power supply voltage becomes less than the specified value. In some cases, the operating voltage of the microcomputer is generated from the voltage obtained by boosting the external power supply voltage by a booster circuit. For this reason, even if the external power supply voltage drops below the specified value, the microcomputer can operate.

  The microcomputer determines whether the input signal that is in the high state is the external power supply voltage or the voltage that is proportional to the external power supply voltage and becomes the ground voltage in the low state is high or low. And a control process for controlling the control target based on the determination result of the input signal by the signal determination process.

  In particular, the microcomputer performs a voltage detection process, a low threshold setting process, and a low-side determination process as a low determination process for determining that the input signal has become low in the signal determination process.

  First, in the voltage detection process, the voltage values of the input signal and the external power supply voltage are detected by an A / D converter that operates in response to the operating voltage. The A / D converter may be either built in the microcomputer or provided outside the microcomputer.

  Further, in the low threshold value setting process, the low determination threshold value for determining that the input signal has changed from high to low is smaller as the detection value is smaller according to the detection value of the external power supply voltage by the voltage detection process. Set to be a value.

  In the low-side determination process, the voltage detection value of the input signal obtained by the voltage detection process is compared with the low determination threshold value set by the low threshold setting process, and the voltage detection value of the input signal is determined to be equal to or lower than the low determination threshold value. In this case, the determination result of the input signal is set to low (that is, it is determined that the input signal is in the low state).

  According to such an electronic control device of claim 1, the lower the external power supply voltage is, the smaller the low determination threshold value is set. Therefore, when the input signal is in the high state, the external power supply voltage is Even if the voltage of the input signal decreases and the input signal decreases, it can be prevented that the input signal is erroneously determined to be in the low state. In addition, the high / low determination result of the input signal is not held, and it can be determined if the input signal really changes from the high state to the low state. Therefore, it is possible to accurately determine that the input signal has changed from the high state to the low state, and it is possible to correctly perform the control processing based on the input signal.

  By the way, in the signal determination process, as the high determination process for determining that the input signal becomes high, for example, the voltage detection value of the input signal by the voltage detection process is set to the low threshold value set by the low threshold setting process. A process of setting the input signal determination result to high when it is determined that the determination threshold value is exceeded is conceivable. That is, the low determination threshold can also be used as a high determination threshold for determining that the input signal has changed from low to high.

  Further, according to the second aspect of the present invention, it is possible to give hysteresis to the low determination threshold and the high determination threshold, and erroneously determine the state of the input signal (whether it is high or low) by noise. It is possible to reduce the possibility of doing so.

  That is, in the electronic control device according to the second aspect, the microcomputer performs a high threshold setting process and a high side determination process as the high determination process. First, in the high threshold setting process, the high determination threshold is set to a smaller value and a value larger than the low determination threshold according to the detection value of the external power supply voltage by the voltage detection process. Set as follows. In the high side determination process, the voltage detection value of the input signal by the voltage detection process is compared with the high determination threshold value set by the high threshold setting process, and the voltage detection value of the input signal is determined to be equal to or higher than the high determination threshold value. In this case, the determination result of the input signal is set to high (that is, it is determined that the input signal is in the high state).

  Next, in the electronic control device according to claim 3, in the electronic control device according to claims 1 and 2, in the voltage detection process, the microcomputer uses the A / D converter to set each voltage value of the input signal and the external power supply voltage. It is designed to detect continuously.

  According to this configuration, the voltage values of the input signal and the external power supply voltage can be detected with substantially the same tying, and the determination accuracy of the input signal can be improved. This is because the low determination threshold and the high determination threshold can be set according to the external power supply voltage when the voltage value of the input signal is detected.

  Next, according to a fourth aspect of the present invention, in the electronic control device according to the first to third aspects, each of the input signal and the external power supply voltage is input to the A / D converter via separate filter circuits. It is like that. The input signal filter circuit and the external power supply voltage filter circuit are configured to have the same time constant.

  That is, not only the input signal but also the external power supply voltage is input to the A / D converter through the filter circuit having the same time constant as the filter circuit of the input signal. In addition, a plurality of filter circuits are configured so that their time constants are the same. The form and components of these filter circuits are selected so that their time constants are the same. Means.

According to this configuration, since the phase shift between the input signal input to the A / D converter and the external power supply voltage can be eliminated, the determination accuracy of the input signal can be improved.
According to a fifth aspect of the present invention, in the electronic control device according to the first to fourth aspects, the input signal is also input to the input port of the microcomputer. If the microcomputer determines that the external power supply voltage is higher than a predetermined value, the microcomputer determines whether the input signal is high or low as the signal determination process. In general, in a microcomputer, logic 1 or logic 0, which is a determination result of high / low at an input port, is stored in a port register in the microcomputer. When the input port determines whether the input signal is high or low, the high / low determination result at the input port is read from the port register, and the read determination result is handled as the input signal determination result. It means that.

  According to such an electronic control device of claim 5, when the external power supply voltage is higher than a predetermined value, the state of the input signal is determined by the input port, so that the processing load on the microcomputer is reduced. Can do. The predetermined value may be set to a value of the external power supply voltage that is considered to cause no erroneous determination even if the state of the input signal is determined at the input port.

  Next, in the electronic control device according to a sixth aspect, in the electronic control device according to the first to fifth aspects, the external power supply voltage is a voltage of a battery mounted on the vehicle, and the input signal is in a high state when the engine is in the vehicle. Is a start permission condition signal which means that the drive of the starter for starting is permitted. Then, the microcomputer performs a process for controlling the starter as a control process. In the control process, when the determination result of the input signal changes from high to low during the starter drive, the starter drive is stopped. It has become.

  According to such an electronic control device, even if the battery voltage decreases due to the starter being driven and the voltage of the input signal in the high state decreases, it is erroneously determined that the input signal is in the low state. Therefore, the starter drive is not accidentally stopped. Further, if the input signal really changes from the high state to the low state, it is possible to determine that fact and to stop the starter drive reliably. Therefore, the starter control process can be performed correctly.

Next, in an electronic control device according to a seventh aspect, in the electronic control device according to the sixth aspect, the microcomputer shortens the execution interval of the signal determination process while the starter is being driven.
According to such an electronic control device, when the input signal as the start permission condition signal changes from the high state to the low state during driving of the starter, it is determined as soon as possible and the driving of the starter is immediately stopped. This is advantageous in terms of safety.

For example, the following methods (1) to (3) are conceivable as a specific method for shortening the execution interval of the signal determination process during driving of the starter.
(1) While the starter is actually driven, the execution interval of the signal determination process is shortened.
(2) The execution interval of the signal determination process is shortened for a certain time from the start of driving the starter.
(3) Since the battery voltage decreases when the starter driving is started, the execution interval of the signal determination process is shortened when the battery voltage is equal to or less than a certain value (a value expected to be driven by the starter). To do.

  Next, in the electronic control device according to an eighth aspect, in the electronic control device according to the sixth and seventh aspects, when the microcomputer determines that the input signal has changed from high to low during driving of the starter, a certain time from that point is determined. The signal determination process is not executed.

  According to such an electronic control device, even if noise is added to the input signal after the input signal becomes low while the starter is driven, it is erroneously determined that the input signal becomes high. Therefore, the possibility of erroneously driving the starter can be eliminated, which is advantageous in terms of safety. In general, the input signal as the start permission condition signal is a signal that changes between high and low in response to an operation on any operation unit by the vehicle driver like the brake signal described above. After changing from high to low, it is unlikely that it will immediately return to high. Therefore, there is no problem even if a fixed dead time during which the signal determination process is not executed is provided.

  Next, in an electronic control device according to a ninth aspect, in the electronic control device according to any one of the sixth to eighth aspects, when the external power supply voltage is not more than a specific value, the microcomputer Only the low determination process including the detection process, the low threshold value setting process, and the low side determination process is performed.

  According to this configuration, when the external power supply voltage becomes a specific value or less by driving the starter, only the low determination process using the A / D converter is performed. If it goes low, it is possible to accurately determine this and stop the drive of the starter. In addition, the noise of the high direction is added to the input signal until the external power supply voltage recovers and becomes higher than a specific value. Even if it gets on, there is no misjudgment that the input signal has become a high state, and the possibility of erroneously re-starting the starter can be eliminated. Therefore, safety can be improved.

  Next, in the electronic control device according to a tenth aspect, in the electronic control device according to the first to ninth aspects, the microcomputer reduces the operating voltage even if the external power supply voltage is boosted by the booster circuit, and the A / D converter. When the A / D conversion accuracy becomes lower than the lower limit value considered to deteriorate, the determination result of the input signal is not changed.

According to this configuration, it is possible to prevent the state of the input signal from being erroneously determined when the external power supply voltage is lowered to the extent that it cannot be boosted and the accuracy of the A / D converter deteriorates.
Next, in the electronic control device according to claim 11, the microcomputer performs the voltage detection processing, the low threshold setting processing, and the low side as the low determination processing in the signal determination processing, as in the electronic control device according to claim 1. Judgment processing is performed.

  According to this electronic control device, the lower the external power supply voltage, the smaller the low determination threshold value is set. Therefore, when the input signal is in the high state, the external power supply voltage decreases and the input Even if the voltage of the signal decreases, it can be prevented that the input signal is erroneously determined to be in the low state. Also, if the input signal really goes from the high state to the low state, this can be determined. Therefore, it can be accurately determined that the input signal has changed from the high state to the low state.

  Next, in an electronic control device according to a twelfth aspect, in the electronic control device according to the eleventh aspect, the microcomputer sets a high threshold value as in the electronic control device according to the second aspect as the high determination processing in the signal determination processing. Processing and high-side determination processing are performed.

  According to the electronic control device of the twelfth aspect, it is possible to give hysteresis to the low determination threshold and the high determination threshold, and erroneously determine the state of the input signal (whether it is high or low) by noise. The possibility that it will end up can be reduced.

The magnitude relationship between the “predetermined value” according to claim 5, the “specific value” according to claim 9, and the “lower limit value” according to claim 10 is [[predetermined value] ≧ “ Specific value ">" lower limit "].
Further, in the low-side determination processing according to claims 1 and 11, if it is continuously determined a plurality of times that the voltage detection value of the input signal is equal to or lower than the low determination threshold, the determination result of the input signal is set to low. Anyway. Similarly, in the high-side determination processing according to claims 2 and 12, if it is continuously determined a plurality of times that the voltage detection value of the input signal is equal to or higher than the high determination threshold, the determination result of the input signal is set to high. You may do it.

  Then, even if the voltage of the input signal fluctuates near the threshold due to noise, it is possible to prevent the determination result of the input signal from being switched. Further, such a noise removal method is also applied to the electronic control device according to claim 5 when the external power supply voltage is higher than a predetermined value and the input port determines whether the input signal is high or low. can do. Specifically, if the high / low determination result read from the port register is the same value for a plurality of consecutive times, the value may be set as the input signal determination result. .

Hereinafter, an electronic control device according to an embodiment to which the present invention is applied will be described. An electronic control device (hereinafter referred to as ECU) of this embodiment is a power supply control ECU that is mounted on a vehicle and performs control to supply power to other ECUs in the vehicle, and starts an engine of the vehicle. Start control is also performed.
[First Embodiment]
As shown in FIG. 1, the ECU 1 of the first embodiment includes a microcomputer 3, a power supply circuit 5, a booster circuit 7, and a drive circuit 9.

  The power supply circuit 5 is a constant for operating the microcomputer 3 from the battery voltage VB as the external power supply voltage supplied from the battery 11 mounted on the vehicle at the normal time when the boost instruction signal Su from the microcomputer 3 is not received. An operating voltage VD (for example, 5V) is generated and output.

  The microcomputer 3 operates in response to the operating voltage VD from the power supply circuit 5. During the operation, the microcomputer 3 detects the battery voltage VB by the built-in A / D converter, and the battery voltage VB is a specified value (this embodiment). If it is determined that the voltage is 7 V or less, the boost instruction signal Su is output to the power supply circuit 5.

  When the power supply circuit 5 receives the boost instruction signal Su, the power supply circuit 5 outputs the boost instruction signal Su to the booster circuit 7, and generates and outputs the operating voltage VD from the output voltage VU of the booster circuit 7. .

Further, when receiving the boost instruction signal Su, the booster circuit 7 boosts the battery voltage VB to a predetermined voltage or higher (for example, 7 V or higher) and outputs the boosted voltage to the power supply circuit 5.
For this reason, when the battery voltage VB is higher than the specified value (= 7V), the operating voltage VD of the microcomputer 3 is generated from the battery voltage VB. However, when the battery voltage VB becomes lower than the specified value. The operating voltage VD is generated from the voltage VU obtained by boosting the battery voltage VB by the booster circuit 7.

  On the other hand, the drive circuit 9 energizes the coil of the power supply relay 13 provided outside the ECU 1 in response to a power supply relay on command from the microcomputer 3. Then, the power relay 13 is turned on, and the battery voltage VB is supplied as power to the engine ECU 15 that controls the engine and other ECUs (not shown).

  The drive circuit 9 energizes the coil of the starter relay 17 provided outside the ECU 1 in response to a starter relay on command from the microcomputer 3. Then, the starter relay 17 is turned on, the battery voltage VB is supplied to the starter 19 for starting the engine, and the starter 19 is operated, whereby the engine is cranked.

  Further, the ECU 1 serves as an input circuit for inputting the battery voltage VB to the A / D conversion input terminal AD1 of the microcomputer 3, and is divided by the two resistors 21 and 22 that divide the battery voltage VB and the resistors 21 and 22. A filter circuit (low-pass filter circuit) including a resistor 23 and a capacitor 24 that integrates the pressed voltage and inputs the integrated voltage to the A / D conversion input terminal AD1 is provided.

  Further, the ECU 1 receives a start signal via the signal line 28 that is set to the battery voltage VB as the high state when the start switch 27 is turned on and becomes the ground voltage as the low state when the start switch 27 is turned off. Further, the brake signal 29 is input to the ECU 1 via the signal line 30 as a battery voltage VB as a high state when the brake switch 29 is turned on and as a ground voltage as a low state when the brake switch 29 is turned off. The start switch 27 is a push-type switch for starting the engine, and is turned on when being pushed by the vehicle driver. The brake switch 29 is a switch for detecting whether or not the vehicle driver is stepping on the brake pedal, and is turned on when the brake pedal is stepped on.

  The ECU 1 serves as an input circuit for inputting a start signal from the signal line 28 to the A / D conversion input terminal AD2 of the microcomputer 3, and includes two resistors 31, 32 for dividing the start signal, And a filter circuit including a resistor 33 and a capacitor 34 that integrate the voltage divided by 32 and input the voltage to the A / D conversion input terminal AD2.

  Similarly, the ECU 1 serves as an input circuit for inputting a brake signal from the signal line 30 to the A / D conversion input terminal AD3 of the microcomputer 3, and two resistors 41 and 42 for dividing the brake signal, and the resistor 41 , 42 is integrated, and a filter circuit composed of a resistor 43 and a capacitor 44 is provided to input to the A / D conversion input terminal AD3.

  The start signal becomes the ground voltage when the start switch 27 is turned off due to the pull-down action of the resistor 32, and the brake signal becomes the ground voltage when the brake switch 29 is turned off due to the pull-down action of the resistor 42. Is.

  In the present embodiment, the resistance ratio of the resistors 21 and 23, the resistors 31 and 32, and the resistors 41 and 42 is 3 to 1, and the voltage dividing ratio at these resistors is set to 1/4. Has been. That is, the battery voltage VB, the start signal, and the brake signal are each divided into ¼ and input to the A / D conversion input terminals AD1 to AD3 of the microcomputer 3. This is because the battery voltage VB may rise up to about 18V, and even if the battery voltage VB reaches the maximum value, the voltage input to the A / D conversion input terminals AD1 to AD3 of the microcomputer 3 is reduced. This is because the A / D conversion can be performed by the A / D converter in the microcomputer 3 while keeping the operating voltage VD (= 5 V) or less of the microcomputer 3 below.

  Furthermore, in this embodiment, the resistance values of the resistors 23, 33, and 43 that constitute each filter circuit are the same, and the capacitances of the capacitors 24, 34, and 44 are also the same. For this reason, the time constant of each filter circuit is the same.

  In such an ECU 1, the microcomputer 3 uses a built-in A / D converter to perform a high / low state of the start signal and the brake signal (in other words, the start switch 27 and The brake switch 29 is turned on / off).

  When the microcomputer 3 detects that the start switch 27 is turned on from the determination result of the input signal determination processing, the microcomputer 3 outputs a power relay on command to the drive circuit 9 to turn on the power relay 13, and the engine ECU 15 and the like. The battery voltage VB is supplied to the ECU.

Further, the microcomputer 3 executes the start control process of FIG. 2 at regular intervals when the engine is not in an operating state (when it is stopped or not in a complete explosion state).
As shown in FIG. 2, when the microcomputer 3 starts the start control process, first, in S110, it is determined whether or not the starter 19 is being driven. If the starter 19 is not being driven, the process proceeds to S120. Thus, it is determined whether or not the start switch 27 is turned on with reference to the determination result of the start signal by the input signal determination process (FIG. 3) described later.

  If it is determined that the start switch 27 is not turned on (S120: NO), the start control process is terminated as it is, but if it is determined that the start switch 27 is turned on (S120: YES), the process proceeds to S130.

If it is determined in S110 that the starter 19 is being driven (S110: YES), the process proceeds to S130.
In S130, it is determined whether or not the brake switch 29 is turned on with reference to a brake signal determination result by an input signal determination process (FIG. 3) described later, and it is determined that the brake switch 29 is turned on. (S130: YES), the process proceeds to S140.

  In S140, the starter relay on command is output to the drive circuit 9, and the starter relay 17 is turned on to drive the starter 19. And this state continues until the process of S160 mentioned later is performed.

  Next, in S150, it is determined whether or not the engine is in a complete explosion state. If the engine is not in a complete explosion state, the start control process is terminated as it is. In this case, at the next execution of the start control process, “YES” is determined in S110, and the process proceeds to S130. Therefore, when it is determined in S150 that the engine is not in the complete explosion state, it is determined again in S130 whether the brake switch 29 is on or off.

  When the starter 19 is driven and engine cranking is started, the engine ECU 15 starts fuel injection and ignition control for each cylinder of the engine. Then, the microcomputer 3 determines whether or not the engine is in a complete explosion state based on, for example, the engine speed. Further, the engine speed is acquired by data communication from the engine ECU 15, or a signal from a rotation sensor for detecting the engine speed is directly taken in and detected.

  If it is determined in S150 that the engine is in a complete explosion state, or if it is determined in S130 that the brake switch 29 is not turned on, the process proceeds to S160. In S160, the starter relay on command is stopped and the starter relay 17 is turned off to stop the starter 19 from being driven. Then, the start control process is finished.

  By such a start control process, if the start switch 27 is turned on while the brake switch 29 is on, the starter 19 starts to be driven. Thereafter, even if the start switch 27 is turned off, the engine is in a complete explosion state. The starter 19 is driven until Even before the engine reaches a complete explosion state, if the brake switch 29 is turned off, the drive of the starter 19 is stopped. That is, in the present embodiment, the brake signal indicating on / off of the brake switch 29 is the start permission condition signal.

Next, the input signal determination process of FIG. 3 executed by the microcomputer 3 will be described. This input signal determination process is executed at regular intervals.
As shown in FIG. 3, when the microcomputer 3 starts executing the input signal determination process, first, in S210, the input signal to be determined as high / low is A / D converted by the built-in A / D converter. In the present embodiment, the start signal input to the A / D conversion input terminal AD2 and the brake signal input to the A / D conversion input terminal AD3 are A / D converted. In the next S220, the battery voltage VB inputted to the A / D conversion input terminal AD1 is A / D converted. In the following, only one of the start signal and the brake signal will be described as an input signal, but the same processing is performed for the other signal.

  Next, in S230, based on the A / D conversion value of the battery voltage VB in S220, it is determined whether or not the current battery voltage VB is higher than a specific value (6 V in the present embodiment). Specifically, the microcomputer 3 uses a value obtained by multiplying the A / D conversion value of the battery voltage VB obtained in S220 by four times as a detection value of the battery voltage VB, and whether or not the detection value is higher than 6V. Determine. And when it determines with the battery voltage VB being higher than 6V, it progresses to S240.

  In S240, a high determination threshold value for determining that the input signal has changed from low to high (in other words, an on determination threshold value for determining that the switch for changing the input signal has been switched from OFF to ON) X Is set from the detected value of the battery voltage VB and a data map of characteristics shown by a dashed line graph in FIG. 4 (hereinafter referred to as a high determination threshold setting map).

  Further, in S240, a low determination threshold value for determining that the input signal has changed from high to low (in other words, an off determination threshold value for determining that the switch that changes the input signal has been turned from on to off). ) Y is set from the detected value of the battery voltage VB and a data map of characteristics shown by the solid line graph in FIG. 4 (hereinafter referred to as a low determination threshold setting map).

  That is, the high determination threshold value setting map is a data map indicating the relationship between the battery voltage and the high determination threshold value, and is set so that the high determination threshold value is proportional to the battery voltage. Similarly, the low determination threshold value setting map is also a data map showing the relationship between the battery voltage and the low determination threshold value, and is set so that the low determination threshold value is proportional to the battery voltage. Further, the high determination threshold value setting map and the low determination threshold value setting map are set so that the high determination threshold value is larger than the low determination threshold value when the battery voltage is the same.

  In S240, the high determination threshold corresponding to the detected value of the battery voltage VB in the high determination threshold setting map is set as the high determination threshold X used in the next S250, and the battery voltage VB in the low determination threshold setting map. The row determination threshold corresponding to the detected value is set as the row determination threshold Y used in the next S250.

  The high determination threshold setting map and the low determination threshold setting map are stored in advance in the internal memory of the microcomputer 3. On the other hand, a calculation formula showing the same contents as such a map is stored, and the high determination threshold value X and the low determination threshold value Y are set by substituting the detection value of the battery voltage VB into the calculation formula. Also good. This also applies to S270 described later.

Next, in S250, a high / low determination process is performed to determine whether the input signal has changed from low to high and from high to low.
That is, in the high / low determination process, the A / D conversion value of the input signal obtained in S210 is compared with the high determination threshold value X and the low determination threshold value Y set in S240, and the A / D conversion value of the input signal is compared. If the A / D conversion value of the input signal is less than or equal to the low determination threshold Y, the input value is set to “high”. Set the signal judgment value to “low”. Further, when the A / D conversion value of the input signal is smaller than the high determination threshold value X and larger than the low determination threshold value Y, the determination value of the input signal is not changed and is kept at the previous value.

  In this embodiment, since the input signal is a high-active switch signal, the input signal determination value “high” means that the switch for changing the input signal is “on”. On the other hand, the determination value of the input signal being “low” means that the switch for changing the input signal is “off”.

Then, in S250, when such a high / low determination process is completed, the input signal determination process is ended.
If it is determined in S230 that the battery voltage VB is not higher than 6V (below 6V), the process proceeds to S260 to determine whether or not the battery voltage is higher than 3V. If it is determined that the battery voltage VB is higher than 3V (ie, “3V <VB ≦ 6V”), the process proceeds to S270.

In S270, the low determination threshold Y is set from the detected value of the battery voltage VB and the low determination threshold setting map of FIG. 4 by the same procedure as in S240 described above.
In step S280, a low determination process is performed to determine that the input signal has changed from high to low.

  That is, in the low determination process, the A / D conversion value of the input signal obtained in S210 is compared with the low determination threshold Y set in S270, and if the A / D conversion value of the input signal is equal to or lower than the low determination threshold Y. For example, the determination value of the input signal is set to “low”. Further, when the A / D conversion value of the input signal is larger than the low determination threshold Y, the input signal determination value is not changed and is kept at the previous value.

Then, in S280, when such a row determination process is completed, the input signal determination process is ended.
If it is determined in S260 that the battery voltage VB is not higher than 3V (below 3V), the process proceeds to S290, and the input signal determination value is not changed and the previous value is left unchanged. Thereafter, the input signal determination process is terminated.

In addition, when the battery voltage VB is 6 V or less, the processing of S270 and S280 is performed without performing the processing of S240 and S250 for the following reason.
That is, as the battery voltage VB decreases, the difference (hysteresis) between the high determination threshold value X and the low determination threshold value Y decreases, so that the possibility of erroneously determining whether the input signal is high or low due to noise increases. In addition, since the input signal (particularly, the brake signal) is in the low state means that the engine start condition has been canceled and is related to safety, it is desired to detect a change in the input signal from high to low.

  Therefore, when the battery voltage VB is 6 V or less, it is not determined whether or not the input signal has changed from low to high, and only whether or not the input signal has changed from high to low is determined by the processing of S270 and S280. Like to do.

  Therefore, when the battery voltage VB becomes 6V or less in the state where the determination value of the input signal is “high”, until it is determined that “A / D conversion value of input signal ≦ low determination threshold Y” in S280, The determination value of the input signal remains “high”, and when it is determined that “A / D conversion value of input signal ≦ low determination threshold Y”, the determination value of the input signal changes from “high” to “low”. Thereafter, as long as the battery voltage VB is 6 V or less, the determination value of the input signal remains “low”.

  According to such processing, when the starter 19 is driven and the battery voltage VB becomes 6 V or less, if the brake switch 29 is turned off and the brake signal changes from the high state to the low state, it is determined. Thus, the drive of the starter 19 can be stopped, and even if high-level noise is applied to the brake signal until the battery voltage VB recovers and becomes higher than 6 V, the brake signal is in the high state. The possibility that the starter 19 is erroneously redriven even if the start switch 27 is turned on can be eliminated.

The reason why the determination value of the input signal is not changed when the battery voltage VB is 3 V or less is as follows.
That is, in the present embodiment, when the battery voltage VB becomes 3 V or less as the lower limit value, the booster circuit 7 cannot sufficiently boost the voltage, and the operating voltage VD output from the power supply circuit 5 decreases from the normal 5 V. there is a possibility. Since the operating voltage VD is also a reference voltage of the A / D converter, when the operating voltage VD is lowered, the A / D conversion accuracy is deteriorated. For this reason, when the battery voltage VB is 3 V or less, the determination of the input signal is not performed based on the A / D conversion result whose accuracy has deteriorated, and the determination result of the input signal is not changed. This prevents erroneous determination of the state of the input signal.

  According to the ECU 1 of the first embodiment as described above, as the battery voltage VB is lower, the low determination threshold value Y is set to a smaller value. Therefore, as illustrated in FIG. Even if the voltage of the brake signal in the high state decreases and the brake signal decreases, it can be prevented that the brake signal is erroneously determined to be in the low state, and the drive of the starter 19 is erroneously stopped. There is nothing. For example, if the battery voltage VB is about 3V (over 3V), the low determination threshold Y is set to about 0.5V as shown in FIG. Until the voltage becomes 2V (= 0.5V × 4) or less, it is not determined to be low, and there is a noise margin of 1V. On the other hand, if the configuration is such that the high / low level of the brake signal is determined by the normal input port of the microcomputer 3, the voltage of the brake signal becomes the high / low determination threshold value (normally) of the input port due to the decrease of the battery voltage VB If it becomes less than 2.5V, which is half of 5V), it will be erroneously determined that the brake signal has become low, and the noise margin is only 0.5V. Thus, according to the present embodiment, erroneous determination of an input signal to low can be prevented.

  Further, according to the ECU 1 of the present embodiment, as shown in FIG. 5, if the brake switch 29 is turned from on to off and the brake signal really changes from the high state to the low state, this can be determined. Thus, the drive of the starter 19 can be stopped reliably. Therefore, the start control process (control process of the starter 19) can be performed correctly.

  Furthermore, in the ECU 1 of the present embodiment, whether or not the input signal has changed from low to high is also determined using the A / D converter. The high determination threshold and the low determination threshold of the input signal are shown in FIG. Since hysteresis is provided as described above, it is possible to reduce the possibility of erroneously determining the high / low state of the input signal due to noise. In particular, while the starter 19 is being driven, the battery voltage VB is not stable, and the high determination and the low determination of the input signal may be repeated. Therefore, it is not possible to provide hysteresis for the high determination threshold and the low determination threshold. It is valid.

  Further, in the present embodiment, in the input signal determination process of FIG. 4, A / D conversion between the input signal and the battery voltage VB is performed continuously (S210, S220). Each voltage value with VB can be detected with substantially the same tying, and the determination accuracy of the input signal can be improved. This is because the low determination threshold Y and the high determination threshold X can be set according to the battery voltage VB when the voltage value of the input signal is detected.

  In the ECU 1 of the present embodiment, not only the input signal but also the battery voltage VB is input to the A / D conversion input terminal AD1 of the microcomputer 3 through the filter circuit having the same time constant as the filter circuit of the input signal. I am doing so. For this reason, it is possible to eliminate the phase shift between the input signal input to the A / D converter in the microcomputer 3 and the battery voltage VB and improve the determination accuracy of the input signal.

Further, by using an A / D converter built in the microcomputer 3, no new parts are required, and an increase in cost can be avoided.
In S250 and S280 of FIG. 3, if it is determined that the A / D conversion value of the input signal is equal to or lower than the low determination threshold Y for a plurality of times, the determination value of the input signal is set to “low”. May be. Similarly, in S250 of FIG. 3, if it is determined that the A / D conversion value of the input signal is equal to or higher than the high determination threshold value X a plurality of times, the determination value of the input signal is set to “high”. Also good. In this way, even if the voltage of the input signal fluctuates in the vicinity of the threshold due to noise, it is possible to prevent the determination value of the input signal from being switched.

On the other hand, in the present embodiment, the input signal determination process in FIG. 3 corresponds to the signal determination process, and the start control process in FIG. 2 corresponds to a control process for controlling the starter 19 as a control target. 3, S210 and S220 correspond to the voltage detection process, a part of S240 (a process for setting the low determination threshold Y) and S270 correspond to the low threshold setting process, and a part of S250 ( If the A / D conversion value of the input signal is equal to or lower than the low determination threshold Y, the process of setting the determination value of the input signal to “low”) and S280 correspond to the low-side determination process. A part of S240 (a process for setting the high determination threshold value X) corresponds to a high threshold setting process, and a part of S250 (if the A / D conversion value of the input signal is equal to or higher than the high determination threshold value X), The process of setting the determination value to “high”) corresponds to the high-side determination process.
[Second Embodiment]
The ECU 1 of the second embodiment is different from the ECU 1 of the first embodiment in that the microcomputer 3 further executes the frequency switching process shown in FIG. This frequency switching process is also executed at regular intervals.

Then, as shown in FIG. 6, when the microcomputer 3 starts executing the frequency switching process, first, in S310, it is determined whether or not the engine is being started.
In S310, for example, it is determined that the starter 19 is being started while the starter 19 is actually being driven, or it is determined that the starter 19 is being started for a certain period of time since the start of driving the starter 19. Further, since the battery voltage VB decreases when the starter 19 starts to be driven, when the battery voltage VB is equal to or lower than a certain value (a value that the starter 19 is expected to be driven) It may be determined.

  If it is determined in S310 that the engine is starting, in S320, the execution interval of the input signal determination process in FIG. 3 is set shorter than the normal value, and then the frequency switching process is performed. Exit. If it is determined in S310 that the engine is not started, the process proceeds to S330, the execution interval of the input signal determination process in FIG. 3 is set to a normal value, and then the frequency switching process is terminated. To do.

According to the ECU 1 of the second embodiment, the execution interval of the input signal determination process is changed to be shorter while the starter 19 is being driven. Therefore, when the brake signal as the start permission condition signal changes from the high state to the low state during the driving of the starter 19, it is possible to quickly determine that and stop the driving of the starter 19 immediately. Is advantageous.
[Third Embodiment]
The ECU 1 of the third embodiment is different from the ECU 1 of the first or second embodiment in that the microcomputer 3 further executes the starter driving process shown in FIG. The starter driving process is executed at regular intervals when the starter 19 is driven.

  Then, as shown in FIG. 7, when the microcomputer 3 starts executing the starter driving process, first, in S410, for each of the start signal and the brake signal, the determination value of the input signal by the input signal determination process is “high”. It is determined whether or not the state has changed from “low” to “low”.

  If “NO” is determined as negative in the determination of S410, the starter driving process is terminated as it is, but if the determination value of the input signal is changed from “high” to “low”, an affirmative determination is made, Proceed to S420.

  In S420, the process for determining high / low (specifically, the processes in S210, S240, S250, S270, and S280 in FIG. 3) for the input signal whose determination value has changed to “low” is constant. The starter is not executed only for a period of time, and then the starter driving process is terminated.

  According to the ECU 1 of the third embodiment, after the start signal or the brake signal is in a low state during driving of the starter 19, even if noise is added to the signal, the signal is in a high state. It is possible to eliminate the possibility of erroneously driving the starter 19 without erroneous determination. Therefore, it is advantageous in terms of safety.

The start signal and the brake signal are signals that change between high and low according to the operation of the vehicle driver, and the state does not change at high speed. Therefore, the starter driving process shown in FIG. 7 may be performed. There is no hindrance in vehicle function.
[Fourth Embodiment]
As shown in FIG. 8, the ECU 51 of the fourth embodiment has a start signal from the signal line 28 and a brake signal from the signal line 30 of the microcomputer 3 compared to the ECU 1 of the first to third embodiments. The input ports IO1 and IO2 are also input via resistors 53 and 55, respectively.

The microcomputer 3 executes the input signal determination process of FIG. 9 instead of the input signal determination process of FIG.
As shown in FIG. 9, in the input signal determination process of the fourth embodiment, first, in S510, the battery voltage VB input to the A / D conversion input terminal AD1 is A / D converted. This S510 is a process corresponding to S220 in FIG.

  Then, in the next S520, it is determined whether or not the current battery voltage VB is higher than a predetermined value (6V in the present embodiment) based on the A / D conversion value of the battery voltage VB in S510, and the battery If it is determined that the voltage VB is higher than 6V, the process proceeds to S530.

In S530, the high / low determination results at the input ports IO1 and IO2 are read from the port registers corresponding to the input ports IO1 and IO2.
In step S540, the value read from the port register (port reading) is set as the input signal determination value. That is, the value read from the port register of the input port IO1 is set as the determination value of the start signal, and the value read from the port register of the input port IO2 is set as the determination value of the brake signal. And after performing the process of S540, the said input signal determination process is complete | finished.

  In S540, for each input signal, if the value read from the port register is the same value a plurality of times in succession, the value is set as the determination value of the input signal, and the noise is processed. You may make it prevent the misjudgment by.

  If it is determined in S520 that the battery voltage VB is not higher than 6V (below 6V), the process proceeds to S550 and the input signal subject to high / low determination is converted into a built-in A / D converter. A / D conversion is performed by the instrument. That is, A / D conversion is performed on the start signal input to the A / D conversion input terminal AD2 and the brake signal input to the A / D conversion input terminal AD3. Note that S550 is processing corresponding to S220 in FIG. Then, after performing the process of S550, the same processes of S260 to S290 as in FIG. 3 are performed.

  In other words, in the fourth embodiment, when the battery voltage VB is higher than 6V, the microcomputer 3 determines whether the input signal is high or low by the input ports IO1 and IO2. . And according to such 4th Embodiment, when the battery voltage VB is higher than 6V, the processing load of the microcomputer 3 can be reduced.

  In FIG. 9, after S550, the same additional processing as in S510 is performed again, and in S270, the low determination threshold Y may be set using the detected value of the battery voltage VB obtained by the additional processing. . In this way, the A / D conversion timing of the input signal can be brought close to the A / D conversion timing of the battery voltage VB for setting the threshold value, and the determination accuracy of the input signal can be improved.

  In addition, the value of the battery voltage VB determined in S520 is not limited to 6V, and is set to the value of the battery voltage VB that is considered to cause no erroneous determination even if the state of the input signal is determined at the input port of the microcomputer 3. Just do it. Therefore, for example, when the battery voltage VB is higher than 8V, the processing of S530 and S540 in FIG. 9 is performed. When the battery voltage VB is lower than 8V and higher than 6V, the processing of S210, S240, and S250 in FIG. When the battery voltage VB is 6V or lower and higher than 3V, the processes of S210, S270, and S280 in FIG. 3 may be performed.

  Also, the value of the battery voltage VB that determines the high / low of the input signal at the input port, and the value of the battery voltage VB that determines the high / low of the input signal using the A / D converter In addition, by providing hysteresis, it may be possible to prevent the process of determining the high / low of the input signal from being frequently switched.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited to such Embodiment at all, Of course, in the range which does not deviate from the summary of this invention, it can implement in a various aspect. .

  For example, the input signal may be a low active switch signal. The low active switch signal may be configured to be input to the A / D conversion input terminal AD of the microcomputer 3 by an input circuit as shown in FIG.

  In FIG. 10, 59 is a signal line connected to the ground voltage when the switch 60 is turned on, and the signal line 59 is always pulled up to the battery voltage VB by the resistor 63. The low active switch signal, which is the voltage of the signal line 59, is divided into ¼ by the resistors 61 and 62 having a resistance value several tens to several hundred times larger than that of the resistor 63, and the A / D conversion of the microcomputer 3 is performed. Input to the input terminal AD. In the input circuit having such a configuration, when the switch 60 is off, the switch signal is approximately the battery voltage VB (specifically, the voltage is proportional to the battery voltage VB, and the battery voltage VB is converted into the resistor 63, the resistor 61, The voltage obtained by dividing the switch signal by the resistors 61 and 62 is input to the A / D conversion input terminal AD of the microcomputer 3. When the switch 60 is on, the switch signal becomes the ground voltage, and the ground voltage is input to the A / D conversion input terminal AD of the microcomputer 3. In FIG. 10, the filter circuit for noise removal is omitted.

On the other hand, the A / D converter may be provided outside the microcomputer 3.
When the transmission of the vehicle is a manual transmission, it is conceivable to use, for example, a switch signal that is turned on when the clutch pedal is depressed, instead of the brake signal, as the start permission condition signal.

It is a block diagram showing the structure of the electronic control apparatus of 1st Embodiment. It is a flowchart showing a start control process. It is a flowchart showing the input signal determination process of 1st Embodiment. It is explanatory drawing explaining the setting method of a high determination threshold value and a low determination threshold value. It is explanatory drawing explaining the effect | action of 1st Embodiment. It is a flowchart showing the frequency switching process performed in 2nd Embodiment. It is a flowchart showing the starter drive time process performed in 3rd Embodiment. It is a block diagram showing the structure of the electronic control apparatus of 4th Embodiment. It is a flowchart showing the input signal determination process of 4th Embodiment. It is explanatory drawing explaining another example. It is a time chart explaining a prior art and its problem.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,51 ... Electronic control ECU, 15 ... Engine ECU, 3 ... Microcomputer, 5 ... Power supply circuit, 7 ... Booster circuit, 9 ... Drive circuit, 11 ... Battery, 13 ... Power supply relay, 17 ... Starter relay, 19 ... Starter, 21 to 23, 31 to 33, 41 to 43, 53, 55, 61 to 63 ... resistor, 24, 34, 44 ... capacitor, 27 ... start switch, 29 ... brake switch, 28, 30, 59 ... signal line, 60 …switch

Claims (12)

When the external power supply voltage supplied from outside is higher than the specified value, the microcomputer operating voltage is generated from the external power supply voltage, and the external power supply voltage is less than the specified value. In this case, the operating voltage is generated from the voltage obtained by boosting the external power supply voltage by the booster circuit.
Furthermore, the microcomputer is a signal for determining whether the input signal that becomes the ground voltage when the external power supply voltage is in a high state or a voltage that is proportional to the external power supply voltage and that is in a low state is high or low. In an electronic control device that performs a determination process and a control process for controlling a control target based on a determination result of the input signal by the signal determination process,
The microcomputer is
Among the signal determination processes, as a low determination process for determining that the input signal has become low,
A voltage detection process of detecting each voltage value of the input signal and the external power supply voltage by an A / D converter operating in response to the operating voltage;
The low determination threshold value for determining that the input signal has changed from high to low is set to be smaller as the detection value is smaller in accordance with the detection value of the external power supply voltage by the voltage detection processing. Low threshold setting processing to be set;
When the voltage detection value of the input signal by the voltage detection process is compared with the low determination threshold value set by the low threshold setting process, and when the voltage detection value of the input signal is determined to be less than or equal to the low determination threshold value, Performing low-side determination processing for setting the input signal determination result to low,
An electronic control device. The electronic control device according to claim 1.
The microcomputer is
Among the signal determination processes, as a high determination process for determining that the input signal has become high,
According to the detection value of the external power supply voltage by the voltage detection process, the high determination threshold for determining that the input signal has changed from low to high, the smaller the detection value, and A high threshold setting process for setting the value to be larger than the low determination threshold;
When the voltage detection value of the input signal by the voltage detection process is compared with the high determination threshold value set by the high threshold setting process, and when the voltage detection value of the input signal is determined to be greater than or equal to the high determination threshold value, Performing high-side determination processing for setting the input signal determination result to high,
An electronic control device. The electronic control device according to claim 1 or 2,
The microcomputer continuously detects the voltage values of the input signal and the external power supply voltage by the A / D converter in the voltage detection process,
An electronic control device. The electronic control device according to any one of claims 1 to 3,
Each of the input signal and the external power supply voltage is input to the A / D converter via a separate filter circuit, and
The input signal filter circuit and the external power supply voltage filter circuit are configured to have the same time constant.
An electronic control device. The electronic control device according to any one of claims 1 to 4,
The input signal is also input to the input port of the microcomputer,
When the microcomputer determines that the external power supply voltage is higher than a predetermined value, the signal determination process includes a process of determining whether the input signal is high or low at the input port. What to do,
An electronic control device. The electronic control device according to any one of claims 1 to 5,
The external power supply voltage is a voltage of a battery mounted on the vehicle,
The input signal is a start permission condition signal that means that a high state permits driving of a starter for starting the engine of the vehicle;
The microcomputer performs processing for controlling the starter as the control processing. In the control processing, when the determination result of the input signal changes from high to low during driving of the starter, driving of the starter is performed. That it is supposed to stop,
An electronic control device. The electronic control device according to claim 6.
The microcomputer shortens an execution interval of the signal determination process during driving of the starter;
An electronic control device. The electronic control device according to claim 6 or 7,
When the microcomputer determines that the input signal has changed from high to low during driving of the starter, the microcomputer does not execute the signal determination processing for a certain period of time from that point.
An electronic control device. The electronic control device according to any one of claims 6 to 8,
When the external power supply voltage is equal to or lower than a specific value, the microcomputer uses the voltage detection process, the low threshold value setting process, and the low-side determination process among the signal determination processes. Only to process,
An electronic control device. The electronic control device according to any one of claims 1 to 9,
In the microcomputer, even if the external power supply voltage is boosted by the booster circuit, the operating voltage decreases and the A / D conversion accuracy of the A / D converter deteriorates, so that the A / D conversion accuracy is deteriorated. If so, the input signal determination result is not changed,
An electronic control device. In addition to having a microcomputer, the microcomputer determines whether the input signal that is in the high state is the external power supply voltage or a voltage that is proportional to the external power supply voltage and becomes the ground voltage in the low state is high or low. In the electronic control device that performs the signal determination process of
The microcomputer is
Among the signal determination processes, as a low determination process for determining that the input signal has become low,
Voltage detection processing for detecting each voltage value of the input signal and the external power supply voltage by an A / D converter;
The low determination threshold value for determining that the input signal has changed from high to low is set to be smaller as the detection value is smaller in accordance with the detection value of the external power supply voltage by the voltage detection processing. Low threshold setting processing to be set;
When the voltage detection value of the input signal by the voltage detection process is compared with the low determination threshold value set by the low threshold setting process, and when the voltage detection value of the input signal is determined to be less than or equal to the low determination threshold value, Performing low-side determination processing for setting the input signal determination result to low,
An electronic control device. The electronic control device according to claim 11,
The microcomputer is
Among the signal determination processes, as a high determination process for determining that the input signal has become high,
According to the detection value of the external power supply voltage by the voltage detection process, the high determination threshold for determining that the input signal has changed from low to high, the smaller the detection value, and A high threshold setting process for setting the value to be larger than the low determination threshold;
When the voltage detection value of the input signal by the voltage detection process is compared with the high determination threshold value set by the high threshold setting process, and when the voltage detection value of the input signal is determined to be greater than or equal to the high determination threshold value, Performing high-side determination processing for setting the input signal determination result to high,
An electronic control device.

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