JP4581978B2 - Fuel injection control device - Google Patents

Description

  The present invention relates to an apparatus for driving an injector for injecting fuel, and more particularly to a fuel injection control apparatus for discharging high voltage energy charged in a capacitor to the injector to open the injector.

Conventionally, as a fuel injection control device that controls fuel injection by driving an injector, a booster circuit that generates a boosted voltage higher than a power supply voltage in a capacitor, a switching element that discharges the capacitor, and the switching element that is turned on / off A device including a control circuit that performs off control is known (see, for example, Patent Document 1). In such a device, at the start of the energization period (injector drive period) in which the injector is energized, a command to turn on the switching element (hereinafter referred to as an on command) is output from the control circuit to turn on the switching element, Discharge. Then, the boosted voltage generated in the capacitor is applied to the injector, and the injector is quickly opened. Thereafter, the injector is kept open until the energization period ends.
JP 2001-14046 A

  By the way, in recent years, it has become mainstream to perform so-called multistage injection for each cylinder of an internal combustion engine. In the fuel injection control device as described above, a capacitor having a larger capacity is used for performing multistage injection. Needed. An aluminum electrolytic capacitor can be considered as a large-capacity capacitor. Here, when this aluminum electrolytic capacitor is used, the variation in the time from when the ON command is output from the control circuit to when the injector opens (hereinafter referred to as valve opening arrival time) increases.

  First, regarding variations in valve opening arrival time, this is because the time from when the ON command is output from the control circuit until the switching element is turned on (hereinafter referred to as ON response time) is the response characteristic of the switching element. This is because of fluctuations. Another reason is that the time from when the voltage is applied to the injector due to the discharge of the capacitor until the injector opens (hereinafter, valve opening response time) varies. The valve opening response time is shortened when a voltage applied to the injector (hereinafter, applied voltage) is increased, and conversely, is increased when the applied voltage is decreased.

  As for the fluctuation of the applied voltage, for example, when the heat generation temperature of the element in the energization path to the injector rises or the internal resistance of the element increases, the voltage drop in the energization path increases, and the applied voltage becomes descend. That is, the applied voltage varies depending on the state of elements in the energization path. In addition, for example, the applied voltage varies even when the ambient temperature of the capacitor varies. Specifically, when the ambient temperature of the capacitor decreases, the equivalent circuit resistance (ESR) of the capacitor increases. Then, the voltage applied to the injector decreases. Further, when the ambient temperature of the capacitor rises, the ESR of the capacitor decreases, and the voltage applied to the injector increases. In particular, in an aluminum electrolytic capacitor, variation due to the ambient temperature of ESR is large. Therefore, when the aluminum electrolytic capacitor is used in the fuel injection control device, the variation in valve opening arrival time becomes large.

  When the on-response time or the valve-opening response time becomes longer (that is, when the valve-opening arrival time becomes longer), the fuel injection amount during the energization period decreases because the start timing of fuel injection to the internal combustion engine is delayed. To do. Further, for example, when the on-response time is normal and the valve-opening response time is short (that is, when the valve-opening arrival time is short), the start timing of fuel injection to the internal combustion engine is advanced. The fuel injection amount increases.

  If the amount of fuel injected into the internal combustion engine decreases too much, it is conceivable that NOx and particulate matter (PM) in the exhaust gas increase. On the other hand, if the fuel injection amount increases too much, the above-mentioned problems occur, and the fuel consumption deteriorates.

  The present invention has been made in view of these problems, and an object of the present invention is to provide a fuel injection control device that ensures a desired fuel injection amount in an internal combustion engine.

The fuel injection control device of the present application made to achieve the above object includes a capacitor, a high voltage generating means for generating a high voltage having a predetermined voltage value higher than the power supply voltage by charging the capacitor, and a capacitor The injector is opened by discharging from the internal combustion engine to inject fuel into the internal combustion engine, the setting means for setting the drive period of the injector, and the energization path of the injector, and is turned on from the capacitor to the injector And a switching element for discharging. When the discharge control means outputs an ON command for turning on the switching element to the switching element at the start timing of the driving period set by the setting means, the switching element is turned on and the capacitor is discharged from the injector. The

Then, the arrival time measuring means measures the arrival time from when the ON command is output from the discharge control means until the discharge current from the capacitor flowing to the injector reaches the specified value, and the difference time detecting means is the arrival time measuring means. The difference time obtained by subtracting the predetermined arrival time determined in advance from the arrival time measured by the above is detected. Further, the correction means, as a correction process for increasing and decreasing the fuel injection quantity of the internal combustion engine, according to the difference time the start timing of the driving period set by the setting means, soon as the difference time is greater in the positive direction The correction process is performed so as to be delayed as the difference time increases in the negative direction .

  The specified arrival time may be a theoretical arrival time that is calculated in advance from parameters of elements in the circuit. Further, the specified arrival time may be a standard arrival time calculated in advance by an experiment or the like.

  According to the fuel injection control device, the fuel injection amount to the internal combustion engine is increased or decreased according to the difference time, and the fuel injection amount is controlled to an appropriate amount. Therefore, it is possible to prevent the NOx and PM in the exhaust gas from increasing due to the excessive decrease in the fuel injection amount, while the above problem is caused by the excessive increase in the fuel injection amount. It is possible to prevent the occurrence or deterioration of fuel consumption.

  Here, for example, the fact that the above-mentioned difference time is positive means that the arrival time measured by the arrival time measuring means is longer than the prescribed arrival time, which means that the injector valve opening timing is delayed. It is that. When the injector opening timing is delayed, the fuel injection amount to the internal combustion engine is reduced according to the delay. Therefore, in this case, the correction means may increase the fuel injection amount to the internal combustion engine as the correction process.

  Also, the negative difference time means that the arrival time is shorter than the prescribed arrival time, which means that the valve opening timing is advanced. Then, the fuel injection amount to the internal combustion engine increases according to the earlier time. Therefore, in this case, the correction means may reduce the fuel injection amount to the internal combustion engine as the correction process.

In the apparatus of the present invention, as described above, the start timing of the drive period is corrected so as to be earlier as the difference time is larger in the positive direction, and is corrected so as to be later as the difference time is larger in the negative direction. . When the start timing of the drive period is advanced, the valve opening period is lengthened and the fuel injection amount is increased. When the start timing of the drive period is delayed, the valve opening period is shortened and the fuel injection amount is decreased. In the apparatus of the present invention, the correction means corrects the start timing of the drive period, whereby the fuel injection amount is controlled to an appropriate amount, and a desired fuel injection amount is ensured.
Further, as a method other aspects increasing or decreasing the fuel injection amount, it is conceivable to correct the period of open state of Lee Njekuta is maintained. That is, after the Lee Njekuta is opened, e Bei holding means for holding the open state, compensation means, as a correction process, the hold period the holding means to hold the injector open state, differential time Accordingly, the longer the difference time is in the positive direction, the longer the difference time is. The longer the difference time is in the negative direction, the shorter the difference time is.

The fuel injection amount increases as the holding period is longer, and the fuel injection amount decreases as the holding period is shorter.
According to such an apparatus, a desired fuel injection amount can be ensured by controlling the fuel injection amount to an appropriate amount by a relatively simple process of increasing or decreasing the holding period.

Further, in the apparatus of the present invention, as the correction process , the correction means increases the charging voltage of the capacitor by the high voltage generation means in accordance with the difference time as the difference time increases in the positive direction, and the difference time is in the negative direction. You may make it reduce, so that it is large.

  If the charging voltage of the capacitor increases, the voltage applied to the injector also increases, so that the valve opening timing is advanced and the amount of fuel injection to the internal combustion engine increases. Conversely, if the charging voltage of the capacitor decreases, the fuel injection amount to the internal combustion engine decreases.

  In this apparatus, when the fuel injection amount is increased or decreased, if the charging voltage of the capacitor is increased or decreased without increasing or decreasing the driving period, for example, the driving period becomes longer and the period between each fuel injection becomes smaller. Therefore, the capacitor is reliably charged. Therefore, it is possible to provide a fuel injection control device that can reliably perform fuel injection and that can control the fuel injection amount to an appropriate amount to ensure a desired fuel injection amount.

Furthermore, if increasing and decreasing the fuel injection amount may be increased or decreased the supply pressure of fuel to Lee Njekuta. Specifically, example Bei pressure control means for controlling the supply pressure of fuel to Lee Njekuta, compensation means, as a correction process, in accordance with the supply pressure to control the pressure control means to the difference time, the differential time It increased larger in the positive direction, that give decreased as the difference time is a negative direction high.

When the supply pressure increases, the fuel injection amount per unit time increases. Conversely, when the supply pressure decreases, the fuel injection amount per unit time decreases.
If the supply pressure is increased / decreased without increasing / decreasing the driving period in this device, the fuel injection can be surely performed for the reason described above, and the fuel injection amount is set to an appropriate amount. The desired fuel injection amount is ensured by the control.

Also, compensation means, differential time it is determined whether within a predetermined range, if not within a predetermined range is preferably adapted to not perform the correction process.

  This is because, for example, when the difference time is larger than a certain value, it is considered that an abnormality has occurred in the circuit, element, etc. When configured as described above, when an abnormality has occurred in the circuit, element, etc. This is because correction processing can be prevented from being performed. And when abnormality of a circuit, an element, etc. is suspected, it is good to implement a fail safe process etc.

  By the way, in this type of fuel injection control device, the internal resistance (ESR) of the capacitor greatly fluctuates in a certain temperature range, and the voltage applied to the injector also fluctuates with the fluctuation. Then, the fuel injection amount varies greatly.

There, so as comprising a temperature detecting means for detecting the ambient temperature of the capacitor, the correction means may ambient temperature detected by the temperature detecting means to determine whether a particular temperature range, to a specific temperature region In some cases, it is preferable to perform correction processing.

According to such an apparatus, the correction unit can be configured to perform the correction process in a temperature region in which the fuel injection amount greatly varies from an appropriate amount. In other words, the correction means can be configured not to perform the correction process in a temperature range where the fuel injection amount does not vary greatly from an appropriate amount and the fuel injection amount does not need to be particularly corrected. Therefore, the processing load on the apparatus can be suppressed, which is advantageous.

However, if those fuel injection control device is in the coolant temperature and is proportional to the ambient temperature and the internal combustion engine in our Ri該 capacitor provided in the vicinity of the internal combustion engine, it is considered that the following configuration. That is, the water temperature detecting means detects the cooling water temperature, and the proportionality determining means detects the cooling water temperature detected by the water temperature detecting means (hereinafter referred to as detected water temperature) and the ambient temperature of the capacitor detected by the temperature detecting means ( Hereinafter, it is determined whether or not the detected ambient temperature is proportional. Furthermore, when it is determined by the proportional determination means that the detected water temperature and the detected ambient temperature are not in a proportional relationship, the abnormality determination means estimates the ambient temperature of the capacitor from the difference time detected by the difference time detection means, The estimated ambient temperature of the capacitor is compared with the detected ambient temperature. Then, the abnormality determining means determines that an abnormality has occurred in the water temperature detecting means when both values can be regarded as the same value.

  In other words, if the proportional relationship between the cooling water temperature and the ambient temperature of the condenser breaks, at least one of the water temperature detection means or the temperature detection means may have an abnormality. It is not possible to determine whether an abnormality has occurred. Therefore, if the ambient temperature is estimated from the difference time and the ambient temperature and the detected ambient temperature can be regarded as the same value, the temperature detection means is estimated to be normal, and in this case, there is an abnormality in the water temperature detection means. It is determined that it has occurred.

According to this, by using the temperature detecting means it can further be able to detect the presence or absence of abnormality of the water temperature detecting means to obtain an excellent effect that. Further, there is no need to provide a separate mechanism for detecting an abnormality in the water temperature detection means, which is advantageous in terms of cost.

The apparatus of the present invention preferably includes a non-volatile time range storage unit that rewriteably stores a predetermined range used by the correction unit for determination of the ambient temperature.

This is because it is easy to change the predetermined range.
The predetermined range may be stored based on input from a vehicle manufacturer or a maintenance person, for example, or may be automatically stored. In the case of automatically storing the difference time, for example, it is conceivable to monitor a difference time and store a predetermined range in which a region in which the value of the monitored difference time is distributed is included. In other words, a predetermined range is optimized.

Moreover, it is preferable that the apparatus of the present invention includes a non-volatile temperature region storage unit that rewritably stores a specific temperature region used by the correction unit for determination of the ambient temperature.

This is because it is easy to change the specific temperature region.
In devices of other aspects, the high voltage generating means described above, the injector, a setting unit, a switching element, and a discharge control means is provided in the et, a temperature detecting means for detecting the ambient temperature of the condenser A correction unit that increases or decreases the fuel injection amount to the internal combustion engine according to the ambient temperature detected by the temperature detection unit may be provided .

  As described above, since the fuel injection amount to the internal combustion engine varies depending on the ambient temperature of the capacitor, in this apparatus, the correction means corrects (increases or decreases) the fuel injection amount according to the ambient temperature of the capacitor. ing. Specifically, the correction means increases the fuel injection amount as the ambient temperature is lower, and decreases the fuel injection amount as the ambient temperature is higher.

According to this device, the fuel injection amount is controlled to an appropriate amount by increasing or decreasing the fuel injection amount in accordance with the ambient temperature of the capacitor, and a desired fuel injection amount is ensured. When increasing or decreasing the amount of fuel injection can be configured as follows.

Specifically, the above-described holding means is provided, and the correction means, as correction processing, lengthens the holding period during which the holding means holds the injector in the valve-open state as the ambient temperature is low, according to the ambient temperature. Conversely, the holding period is shortened as the ambient temperature increases.

Also, Correction means, as the correction processing, the start timing of the driving period set by the setting means in accordance with the ambient temperature is corrected so as to quickly as when the ambient temperature is low. In other words, correction is performed so that the start timing is delayed as the ambient temperature increases.

In addition, the correction means increases the charging voltage of the capacitor by the high voltage generation means in accordance with the ambient temperature as the ambient temperature is lower as the correction process. Conversely, the charging voltage is decreased as the ambient temperature increases.

Furthermore, the pressure control means described above is provided, and the correction means increases the supply pressure controlled by the pressure control means in accordance with the ambient temperature as the ambient temperature is lower as the correction process. Conversely, the supply pressure is reduced as the ambient temperature increases.

According to such an apparatus, since the correction amount (increase / decrease amount) of the fuel injection amount has only to be determined based on the ambient temperature, the processing becomes relatively simple. Therefore, the processing load of the apparatus can be suppressed.

Also, compensation unit determines whether the ambient temperature is in the specific temperature region, when in a specific temperature range, it is preferably adapted to perform the correction process.

  As described above, in this type of fuel injection control device, there is a temperature region in which the fuel injection amount greatly fluctuates from an appropriate amount. Conversely, there is a temperature region where the fuel injection amount does not vary so much from an appropriate amount.

According to the device of the present application, in the temperature range where the fuel injection amount greatly fluctuates from an appropriate amount, the correction means performs the correction process. Conversely, the fuel injection amount does not fluctuate greatly from the appropriate amount, In the temperature range where the fuel injection amount does not have to be particularly corrected, the correction means can be configured not to perform the correction process. Therefore, the processing load on the apparatus can be suppressed, which is advantageous.

Further, in the apparatus of the present application, it is preferable that the compensation means comprises a temperature range storage means of the non-volatile rewritably storing specific temperature region used for the determination of the ambient temperature.

This is because it is easy to change the specific temperature region.
Also, if the fuel injection control apparatus is provided in the vicinity of an internal combustion engine, temperature detecting means may be configured so as to detect a coolant temperature of the internal combustion engine as ambient temperature.

  This is because, when the fuel injection control device is provided in the vicinity of the internal combustion engine, the cooling water temperature of the internal combustion engine and the ambient temperature of the condenser are proportional to each other, and the fuel injection amount is corrected using the cooling water temperature as the ambient temperature. This is because it is the same as correcting the fuel injection amount in accordance with the actual ambient temperature. Further, when a means for detecting the cooling water temperature is separately provided, a configuration in which the correction means uses the detected cooling water temperature as the ambient temperature is also conceivable. In this case, for example, even if the temperature detecting means has an abnormality and the ambient temperature cannot be detected, the correction process can be performed with the cooling water temperature regarded as the ambient temperature, and the fuel injection amount can be controlled. It is possible to provide a fuel injection control device that is made more reliable.

The fuel injection control system of the embodiment to which the present invention is applied will be described below.
As shown in FIG. 1, an engine 1 to be controlled by the fuel injection control system of the present embodiment is a four-cylinder diesel engine having four cylinders 2, and the fuel pumped from the high-pressure fuel pump 3 is a common rail. 4 is accumulated in a high pressure state, and fuel is supplied from the common rail 4 to electromagnetic coil unit injectors (hereinafter simply referred to as electromagnetic valves) 101 to 104 provided in each cylinder.

  In this fuel injection control system, an engine control electronic control unit (hereinafter referred to as ECU) 100 is operated based on a signal from an air flow sensor (also referred to as an air flow meter) 7 provided in an intake path of the engine 1. 1 is detected, and the pressure in the common rail 4 is detected based on a signal from a pressure sensor 8 provided in the common rail 4.

  Further, the ECU 100 includes an accelerator pedal sensor signal indicating the amount of operation of the accelerator pedal, a rotation signal in which a pulse edge is generated at every constant crank angle (for example, every 6 ° CA) in synchronization with the rotation of the crankshaft of the engine 1, an engine A water temperature sensor signal indicating a cooling water temperature of 1, an intake air temperature sensor signal indicating an intake air temperature of the engine 1, a boost sensor signal indicating a boost pressure, an ignition SW signal indicating ON / OFF of an ignition switch (SW), and an ON of a starter switch Various other signals such as a starter SW signal indicating / off are also input. Note that CA is a conventional subscript meaning a crank angle (a rotation angle of the crankshaft).

  The ECU 100 calculates various engine control parameters based on the various input signals and the detected values of the inflow air amount and the pressure in the common rail 4, and based on the calculation results, the high-pressure fuel pump 3 and the electromagnetic The valves 101 to 104 are driven.

Further, the engine 1 is provided with a known intake throttle valve 9, an EGR device 10, and a turbocharger 11 as actuators for emission control, and these actuators are also controlled by the ECU 100.
[Embodiment 1]
FIG. 2 is a diagram illustrating a configuration of the ECU 100 as the fuel injection control device of the first embodiment.

  In the first embodiment, the electromagnetic valves 101, 102, 103, and 104 are normally closed electromagnetic valves having coils 101a, 102a, 103a, and 104a, respectively. When the coils 101a to 104a are energized, A valve body (not shown) moves to the valve opening position against the urging force of the return spring, and fuel injection is performed.

  Further, when the energization of the coils 101a to 104a is cut off, the valve body returns to the original closed position, and fuel injection is stopped. And the energization time and energization timing to the coils 101a to 104a of the electromagnetic valves 101 to 104 are controlled, whereby the fuel injection amount and the fuel injection timing to each cylinder # 1 to # 4 of the engine 1 are controlled. The

  In the present embodiment, so-called multistage injection of fuel is performed for each cylinder. Specifically, in one combustion stroke, pre-injection for the purpose of activation in the cylinder, pilot injection for the purpose of reducing noise, vibration and NOx, main injection for the purpose of driving the piston, and combustion After-injection and post-injection for the purpose of re-combustion of the generated particulate matter (PM) are performed.

Further, in this apparatus, multiple injections are performed in which two electromagnetic valves are simultaneously driven to perform fuel injection, and the following configuration is adopted.
First, the solenoid valves 101 to 104 of all four cylinders are divided into two groups of two cylinders, and the solenoid valves 101 and 103 are made the same injection group, and one end on the upstream side of the coils 101a and 103a is connected to a terminal COM1 provided in the ECU 100 The solenoid valves 102 and 104 are set as the same injection group, and one end on the upstream side of the coils 102a and 104a is connected to a terminal COM2 provided in the ECU 100. Each injection group is composed of solenoid valves that are not driven at the same time. The grouping is determined by the design specifications of the engine 1 such as which cylinders perform multiple injection. In the following description, the constituent elements indicated by <> are for driving the solenoid valves 102 and 104.

  The ECU 100 includes terminals INJ1, INJ3 <INJ2, INJ4> to which the downstream ends of the coils 101a, 103a <102a, 104a> are connected in addition to the terminals COM1 <COM2> and the terminals INJ1, INJ3 <INJ2>. , INJ4> for transistors T10, T30 <T20, T40> having one output terminal connected thereto, and a current detection connected between the other output terminal of transistors T10, T30 <T20, T40> and the ground line. Resistor R10 <R20>, a transistor T11 <T21> having one output terminal connected to a power supply line Lp to which a vehicle-mounted battery voltage (hereinafter referred to as battery voltage) VB as a power supply voltage is supplied, and the transistor The anode is connected to the other output terminal of T11 <T21>, and the cathode A large current for quickly opening the solenoid valves 101, 103 <102, 104> is supplied to the coils 101 a, 103 a <102 a, and the backflow prevention diode D 11 <D 21> connected to the terminal COM 1 <COM 2>. 104a> and a booster circuit 50 that boosts the battery voltage VB, generates a voltage higher than the battery voltage VB, and charges the capacitor C10 <C20>. .

  Further, a discharge transistor T12 <T22> for connecting the positive side of the capacitor C10 <C20> to the terminal COM1 <COM2>, an anode is connected to the ground line, and a cathode is connected to the terminal COM1 <COM2>. A diode D12 <D22> that circulates current to the coils 101a, 103a <102a, 104a> when the transistor T11 <T21> is turned off from the on state with the transistors T10, T30 <T20, T40> turned on; A drive control circuit 120 that controls the transistors T10, T30 <T20, T40>, T11 <T21>, T12 <T22>, and the booster circuit 50, and a known microcomputer (hereinafter simply referred to as a microcomputer) including a CPU, ROM, RAM, and the like. 130) and the ECU 10 Between the temperature sensor H01 for detecting an internal temperature, and EEPROM10 is a memory nonvolatile rewritable information, it is provided.

  In the present embodiment, an aluminum electrolytic capacitor is used as the capacitor C10 <C20>. The aluminum electrolytic capacitor has a smaller volume ratio to the capacitance than, for example, a conventionally used film capacitor. Therefore, it is suitable for use when a high-capacity capacitor is required such as when performing multi-stage injection.

  Here, the microcomputer 130 determines the cylinder based on the operation information of the engine 1 represented by various signals as described above (in FIG. 2, only the rotational speed Ne, the accelerator opening ACC, and the cooling water temperature THW of the engine 1 are shown). Injection command signals S # 1 to S # 4 are generated for each of # 1 to # 4 and output to the drive control circuit 120. The injection command signals S # 1 to S # 4 are energized to the coils 101a to 104a of the electromagnetic valves 101 to 104 only when the level of the signal is high (that is, the electromagnetic valves 101 to 104 are opened). It has a meaning. For this reason, the microcomputer 130 energizes the coils 101a to 104a of the solenoid valves 101 to 104 (drive period of the solenoid valves 101 to 104) for each cylinder # 1 to # 4 based on the operation information of the engine 1. It can be said that the injection command signal of the corresponding cylinder is made high only during the energization period.

  The booster circuit 50 includes an inductor L00, a transistor T00, and a charge control circuit 110 that drives the transistor T00. The inductor L00 has one end connected to the power supply line Lp and the other end connected to one output terminal of the transistor T00.

  A current detection resistor R00 is connected between the other output terminal of the transistor T00 and the ground line. The charge control circuit 110 is connected to the gate terminal of the transistor T00, and the transistor T00 is turned on / off according to the output of the charge control circuit 110. As the charge control circuit 110, a self-excited oscillation circuit is used in detail.

  Furthermore, one end of the positive side of the capacitor C10 <C20> is connected to a connection point between the inductor L00 and the transistor T00 via a backflow prevention diode D13 <D23>. One end on the negative electrode side of the capacitor C10 <C20> is connected to a connection point between the transistor T00 and the resistor R00.

  In such a booster circuit 50, when the transistor T00 is turned on / off, a flyback voltage (back electromotive voltage) higher than the battery voltage VB is generated at the connection point between the inductor L00 and the transistor T00. The capacitor C10 <C20> is charged through the diode D13 <D23> by the back voltage. Thereby, capacitor C10 <C20> is charged to a voltage higher than battery voltage VB.

  Then, when the charge permission signal from the drive control circuit 120 becomes active level (for example, high level), the charge control circuit 110 turns on / off the transistor T00. At this time, the charge control circuit 110 turns on / off the transistor C00 <C20>. When the voltage is monitored and the voltage reaches a preset target value or the charge permission signal from the drive control circuit 120 becomes an inactive level, the transistor T00 remains off and the capacitor C10 <C20> is charged. Stop. Here, the target value is stored in a storage unit (not shown) included in the charge control circuit 110 and can be rewritten by the microcomputer 130. The charge control circuit 110 is provided with a voltage dividing circuit (not shown), and the charge control circuit 110 detects the voltage on the positive side of the capacitor C10 <C20> via the voltage dividing circuit.

  Next, the operation of the fuel injection control apparatus configured as described above will be described with reference to the time chart of FIG. As described above, the drive control circuit 120 receives the injection command signals S # 1 to S # 4 of the cylinders # 1 to # 4 from the microcomputer 130. Here, the first cylinder # 1 is used. The second cylinder # 2 will be described. FIG. 3 shows an operation example of multistage injection and multiple injection. As described above, the multi-stage injection includes pre-injection, pilot injection, main injection, after-injection, and post-injection. These injections are appropriately performed according to operation information of the engine 1 and the like.

  In FIG. 3, “S # 1” indicates an injection command signal for the first cylinder # 1, and “S # 2” indicates an injection command signal for the second cylinder # 2. Further, T10 is turned on when the injection command signal S # 1 becomes high, and T10 is turned off when S # 1 becomes low. The same applies to S # 2 and T20. As multi-stage injection in the first cylinder # 1, pilot injection is performed in the period t1, main injection is performed in the period t2, and as multiple injection, in the period t3, it overlaps with the main injection in the first cylinder # 1, Post injection is performed on the second cylinder # 2.

  First, before the start of pilot injection in the period t1, the drive control circuit 120 sets the charge permission signal to the charge control circuit 110 to an active level to operate the booster circuit 50, and the capacitors C10 and C20 have their voltages set to a predetermined value. The battery is charged until the target value is reached.

  As shown in FIG. 3, when the injection command signal S # 1 of the first cylinder # 1 from the microcomputer 130 to the drive control circuit 120 becomes high, the drive control circuit 120 turns on the transistor T10 as described above. At the same time, the transistor T12 is also turned on.

  Then, the voltage of the capacitor C10 is applied to the terminal COM1 that forms an energization path to the coil 101a, and the energy charged in the capacitor C10 is released to the coil 101a, thereby starting energization of the coil 101a. Is done. At this time, a large current for quickly opening the solenoid valve 101 flows through the coil 101a due to the discharge of the capacitor C10. In addition, when the capacitor C10 is discharged, the wraparound from the terminal COM1 side to the power supply line Lp side, which becomes a high potential, is prevented by the diode D11. In FIG. 3, “INJ1 current I” is a current (hereinafter simply referred to as current I) flowing through the coil 101a.

  Then, the microcomputer 130 and the drive control circuit 120 detect the current I flowing through the coil 101a based on the voltage generated in the resistor R10. Further, the drive control circuit 120 turns off the transistor T12 when the current I reaches the target current value Ip after turning on the transistors T10 and T12. Note that the voltage of the capacitor C10 may be detected instead of the detected value of the current I, and the on / off of the transistor T12 may be controlled based on the voltage.

  In this way, at the start of the energization period to the coil 101a, the transistors T10 and T12 are turned on, and the energy charged in the capacitor C10 is released to the coil 101a, whereby a large current flows through the coil 101a. The valve opening response of the electromagnetic valve 101 is accelerated.

  In addition, the drive control circuit 120 sets the charge permission signal to the charge control circuit 110 to an inactive level and stabilizes the discharge current from the capacitor C10 while the transistor T12 is turned on, and the booster circuit 50 The charging operation of the capacitor C10 by the above (that is, on / off of the transistor T00) is prohibited.

  Then, after turning off the transistor T12, the drive control circuit 120 turns on the transistor T11 so that the current I of the coil 101a detected by the voltage generated in the resistor R10 becomes a constant current smaller than the target current value Ip. / Off control.

  More specifically, the drive control circuit 120 determines that the current I of the coil 101a is the lower threshold IL as constant current control for flowing a constant current through the coil 101a while the injection command signal S # 1 is high. The control is performed so that the transistor T11 is turned on when the current is equal to or lower, and the transistor T11 is turned off when the current I of the coil 101a is equal to or higher than the upper threshold IH. The relationship between the lower threshold value IL, the upper threshold value IH, and the target current value Ip of current is “IL <IH <Ip”. In addition, the circuit portion for performing such constant current control can be configured by a window comparator having a voltage generated in the resistor R10 as an input.

  For this reason, when the current I of the coil 101a decreases from the target current value Ip and becomes equal to or lower than the lower threshold value IL, the transistor T11 is repeatedly turned on / off, and the average value of the current I of the coil 101a becomes higher. The current is controlled to be a constant current approximately in the middle between the threshold value IH and the lower threshold value IL.

  With such constant current control, after the transistor T12 is turned off, a constant current is supplied from the power supply line Lp to the coil 101a via the transistor T11 and the diode D11, and the solenoid valve 101 is opened by the constant current. Hold it. The diode D12 is a reflux diode for such constant current control, and the current flowing through the coil 101a when the transistor T11 is turned off is refluxed through the diode D12.

  Thereafter, when the injection command signal S # 1 from the microcomputer 130 changes from high to low, the drive control circuit 120 turns off the transistor T10 and ends the on / off control (that is, constant current control) of the transistor T11. The transistor T11 is also kept off. Then, energization of the coil 101a is stopped, the solenoid valve 101 is closed, and fuel injection by the solenoid valve 101 is ended.

  When the injection command signal S # 1 becomes low and the transistors T10 and T11 are turned off, flyback energy is generated in the coil 101a as shown in the fourth stage.

  Further, after turning off the transistor T12, the drive control circuit 120 returns the charge permission signal to the charge control circuit 110 to the active level, and performs the charging operation of the capacitor C10 by the booster circuit 50 (turning on / off the transistor T00). Let it resume. This is to prepare for the next solenoid valve drive.

  In FIG. 3, the injection command signal for the main injection in the first cylinder # 1 (period t2) overlaps the injection command signal for the post injection in the second cylinder # 2 (period t3). 102 are driven simultaneously. That is, multiple injection is performed. At this time, since the solenoid valves 101 and 102 belong to different injection groups, they are controlled independently of each other. As shown in FIG. 3, even if the injection timing overlaps, fuel injection is not affected by each other. Is implemented.

  Specifically, when the injection command signal S # 2 of the second cylinder # 2 becomes high in the period t3, the transistor T20 is turned on, the transistor T22 is turned on, and the post injection by the electromagnetic valve 102 is started. That is, the energy charged in the capacitor C20 when the transistors T20 and T22 are turned on is released to the electromagnetic valve 102. Thereby, a large current flows through the coil 102a of the electromagnetic valve 102, and the valve opening response of the electromagnetic valve 102 is accelerated. After the energy release from the capacitor C20, the transistor T21 is controlled to be turned on / off according to the drive current (INJ2 current i) detected by the current detection resistor R20, and a constant current is supplied to the solenoid valve 102 via the diode D21. Is supplied. As a result, the electromagnetic valve 102 is held in an open state.

Thereafter, when the injection command signal S # 2 of the second cylinder # 2 becomes low, the transistor T20 is turned off, the electromagnetic valve 102 is closed, and the post injection by the electromagnetic valve 102 is ended.
When the charge permission signal becomes an active level after T22 is turned off and the transistor T00 starts to be turned on / off, charging of the capacitor C20 by the booster circuit 50 is started.

  In the fuel injection control device of this embodiment, the microcomputer 130 sets the time from when the injection command signal S # 1 is set high until the current value in the coil 101a reaches the target current value Ip (hereinafter referred to as arrival time). ) And the energization period correction process of correcting the energization period to the coil 101a based on the measured arrival time.

  FIG. 4 is a flowchart showing the flow of the energization period correction process, and this energization period correction process is performed by the CPU provided in the microcomputer 130 or a dedicated logic circuit. Moreover, it implements about each cylinder # 1- # 4. Here, the case of the first cylinder # 1 will be described.

  In this process, the microcomputer 130 first starts a timer provided in the microcomputer 130 at the timing when the injection command signal S # 1 is set to high (S110). The measurement of the arrival time described above is started.

  Then, the timer is stopped at the timing when the current value flowing through the coil 101a reaches the target current value Ip (S120). As described above, the current flowing through the coil 101a is detected based on the voltage generated in the resistor R10. And the measurement of arrival time is complete | finished by the process of this S120. Here, in the following description, the time measured by the timer as the arrival time is represented by a symbol Tb such as arrival time Tb.

  In the process of S130, the arrival time Tb is read from the timer. Further, the theoretical time Ta, which is a theoretical value derived by calculation from the charging voltage value of the capacitor C10, the parameters of each element in the circuit, etc., is stored in advance in the ROM, and the microcomputer 130 performs the processing in S130. Then, a difference time Tc obtained by subtracting the theoretical time Ta from the arrival time Tb is calculated.

Here, why such a process is performed will be described with reference to FIG.
FIG. 5 is a time chart showing an example of the operation of the fuel injection control apparatus. Here, the electromagnetic valve 101 will be described. Of the waveforms of the INJ1 current I in FIG. 5, the waveform b represents a waveform based on actual measurement. On the other hand, the waveform a0 represents a waveform derived by calculation from the charging voltage value of the capacitor C10, the parameters of each element in the circuit, and the like as described above. Further, the waveform a1 represents a case where the time at which the waveform a0 appears is delayed by time t4.

  As shown in the waveform a0, theoretically, as soon as the injection command signal S # 1 becomes high, a current starts to flow through the coil 101a, and the electromagnetic valve 101 before the current value reaches the target current value Ip. Is opened and fuel injection into the engine 1 is started. Thereafter, the open state of the electromagnetic valve 101 is maintained, and fuel injection is continued while the electromagnetic valve 101 is open.

  However, in practice, there may be a delay time as indicated by a time t4 in FIG. 5 until the current starts to flow through the coil 101a after the injection command signal S # 1 becomes high. Such a delay time is the time from when the command for turning on the transistor T12 or the transistor T10 is output from the drive control circuit 120 until the transistor T12 or the transistor T10 is actually turned on (that is, the transistor T12 and the transistor T10). It may be caused by a delay in response time (T10).

  Further, there may be a delay in the time from when the current starts to flow through the coil 101a until the electromagnetic valve 101 opens. This is because, for example, when the ambient temperature of the capacitor C10 decreases and the internal resistance of the capacitor C10 increases, the voltage drop in the discharge path of the capacitor C10 increases, and the applied voltage decreases in the coil 101a. For this reason, as indicated by the waveform b, the rise of the current value becomes gradual as compared with the waveform a0 and the waveform a1. Then, as shown in FIG. 5, a delay time as shown by time t5 occurs with respect to the arrival time.

  When the delay times t4 and t5 occur in the arrival time as described above, the valve opening timing of the electromagnetic valve 101 is delayed, and the engine 1 does not inject the amount of fuel that should be injected. Therefore, the actual fuel injection amount is smaller than the theoretical fuel injection amount. Here, in FIG. 5, Qb schematically represents the actual fuel injection amount, and Qc schematically represents the fuel injection amount that is considered to be insufficient from the fuel injection amount that should originally be injected. It is a thing. That is, theoretically, the fuel injection amount should be Qb + Qc, but when the delay times t4 and t5 occur, the fuel injection amount becomes Qb. Thus, if the actual fuel injection amount is less than the theoretical fuel injection amount, problems such as an increase in NOx and PM in the exhaust gas may occur.

  In FIG. 5, time 0 represents the time when the injection command signal S # 1 becomes high, and time Te represents the time when the injection command signal S # 1 became low, that is, the electromagnetic valve 101 is closed. Time. In addition, the same sign as the above-described theoretical time Ta is used for the time Ta, but the time from the time 0 to the time Ta corresponds to the theoretical time Ta, and here, the same sign is used for convenience. Yes. The same applies to Tb.

  In addition, here, the case where the actual fuel injection amount is insufficient than the theoretical fuel injection amount has been described, but conversely, the actual fuel injection amount may increase beyond the theoretical fuel injection amount. . That is, there is no delay time after the injection command signal S # 1 becomes high, current flows through the coil 101a, and the time until the current value reaches the target current value Ip is shorter than the theoretical time. This is the case. In such a case, for example, as the ambient temperature of the capacitor C10 rises and the internal resistance of the capacitor C10 decreases, the voltage drop in the discharge path decreases, and the voltage applied to the coil 101a increases. There may be cases.

  When the voltage applied to the coil 101a increases, the rise of the flowing current value in the coil 101a increases, and the time until the current value reaches the target current value Ip is shortened. In such a case, the opening timing of the solenoid valve 101 is advanced, and excess fuel is injected from the theoretical fuel injection amount, which is a cause of increase in NOx and PM in the exhaust gas. It is not preferable from the viewpoint of fuel consumption.

  That is, if the arrival time Tb deviates significantly from the theoretical time Ta (that is, if the difference time Tc increases), it is considered that a desired fuel injection amount is not ensured, and thus such a problem may occur. For the purpose of verifying, the difference time Tc is calculated in the above-described processing of S110 to S130 (S130).

  In the energization period correction process of FIG. 4, the internal temperature of the ECU 100 (hereinafter simply referred to as the ECU internal temperature) is detected by the temperature sensor H01 (S140). Here, in the following description, the detected ECU internal temperature is represented as a detected temperature K1.

  By the way, as described above, when the ESR of the capacitor C10 varies depending on the ECU internal temperature (that is, the ambient temperature of the capacitor C10), the arrival time Tb also varies. Further, the arrival time Tb varies depending on the state of the elements other than the capacitor C10. For example, when a circuit abnormality or element deterioration occurs, the arrival time Tb is considered to vary greatly.

  In this apparatus, if the difference time Tc obtained by subtracting the theoretical time Ta from the arrival time Tb exceeds a preset allowable range, it is determined that a circuit abnormality or element deterioration has occurred. . In the present embodiment, the allowable range is stored in advance in the EEPROM 10 in association with the ECU internal temperature. That is, an allowable range is defined for each temperature (here, for each constant temperature range). The permissible range can be easily changed. For example, a vehicle maintenance person can rewrite the maintenance range of the apparatus.

  Further, the allowable range may be automatically stored (rewritten). In this case, it is conceivable that an allowable range is set (calculated) by a process (not shown) in the microcomputer 130 and written in the EEPROM 10. More specifically, the microcomputer 130 calculates the difference time Tc for a plurality of times of fuel injection, sets an allowable range so as to include a range in which the difference time Tc is widely distributed, and writes it in the EEPROM 10. be able to. As a result, the allowable range can be optimized.

In S150, an allowable range corresponding to the detected temperature K1 is read from the EEPROM 10.
Next, it is determined whether or not the difference time Tc is within the allowable range. If it is determined that the difference time Tc is within the allowable range (S160: YES), a process for adding the period corresponding to the difference time Tc to the energization period described above. (S170).

  For example, assuming that Tb−Ta = Tc> 0, as shown in FIG. 6, the time when the injection command signal S # 1 becomes low is delayed from the time Te by the difference time Tc. That is, the high period of the injection command signal S # 1 is extended by the difference time Tc. Then, it is possible to prevent the fuel injection amount in the engine 1 from increasing by Qc and increasing NOx and PM in the exhaust gas.

  For example, if Tb−Ta = Tc <0, although not shown, the time when the injection command signal S # 1 becomes low is advanced from the time Te by the difference time Tc. That is, the high period of the injection command signal S # 1 is shortened by the difference time Tc. Then, the fuel injection amount in the engine 1 is reduced by Qc, and the increase in NOx and PM in the exhaust gas of the engine 1 and the deterioration of fuel consumption can be prevented.

  Furthermore, as another embodiment, when Tb−Ta = Tc> 0, the injection command signal S # 1 is set at the time Te when the injection command signal S # 1 becomes low as shown in FIG. It is also possible to advance the time to be high from the time 0 by the difference time Tc. Also by this, the same effect as in the case of FIG. 6 can be obtained.

  In the case of Tb−Ta = Tc <0, although not shown, the time when the injection command signal S # 1 becomes low remains the time Te, and the time when the injection command signal S # 1 becomes high. It can be delayed from the time 0 by the difference time Tc. As a result, it is possible to prevent the fuel injection amount from being decreased and NOx and PM in the exhaust gas from increasing and fuel consumption from being deteriorated.

  When increasing the fuel injection amount, the time at which the injection command signal S # 1 becomes low is delayed from the time Te by the difference time Tc, or the time at which the injection command signal S # 1 is made high is different from the time 0. When the time is advanced by the time Tc or when the fuel injection amount is decreased, the time when the injection command signal S # 1 becomes low is advanced by the difference time Tc from the time Te or the injection command signal S # 1 is made high. Whether to delay the time to be performed by the difference time Tc from time 0 can be appropriately determined from the temporal relationship with the preceding and subsequent fuel injections.

  In S160, if it is determined that the difference time Tc is not within the allowable range (S160: NO), it is determined that the circuit abnormality or the element deterioration has occurred as described above (S180), and the circuit is used as fail-safe processing. Processing such as turning on a warning lamp for notifying the driver of the vehicle that an abnormality such as abnormality or element deterioration has occurred, or prohibiting energization of the solenoid valve 101 is performed ( S190).

In the present embodiment, the booster circuit 50 corresponds to high voltage generation means, the transistors T10 to T40, T12, T22 correspond to switching elements, the microcomputer 130 corresponds to setting means and correction means, and the drive control circuit 120. Corresponds to the discharge control means, the processing of S110 and S120 corresponds to the arrival time measurement means, the processing of S130 corresponds to the difference time detection means, the drive control circuit 120 and the transistors T11 and T21 correspond to the holding means, The temperature sensor H01 corresponds to a temperature detection unit, and the EEPROM 10 corresponds to a time range storage unit. The processing of S170 is equivalent to compensation means.

  According to the fuel injection control device of the present embodiment, the fuel injection amount is corrected according to the difference time Tc and the fuel injection amount to the engine 1 is controlled to an appropriate amount, so that a desired fuel injection amount is ensured. Will come to be.

Further, when the difference time Tc is not within the allowable range, it is determined that an abnormality has occurred in the circuit or element, and the processing for correcting the fuel injection amount is not performed, so the load on the apparatus is unnecessarily increased. Can be prevented.
[Second Embodiment]
Next, the fuel injection control apparatus of 2nd Embodiment is demonstrated. The fuel injection control device of the second embodiment has the same hardware configuration as the fuel injection control device of the first embodiment, and hereinafter, the same reference numerals are used. Moreover, in the following description, although the solenoid valve 101 is demonstrated as an effect | action of this apparatus, it is the same also about the other solenoid valves 102-104.

  In the second embodiment, the microcomputer 130 increases the target value of the charging voltage of the capacitor C10 as a process when the amount of deviation of the arrival time Tb from the theoretical time Ta (that is, the difference time Tc) increases. Corrections such as lowering or lowering are performed.

First, FIG. 8 is a flowchart showing the flow of voltage correction processing executed by the microcomputer 130 of the second embodiment.
This voltage correction process differs from the energization period correction process of FIG. 4 in the process of S170. In this voltage correction process, the microcomputer 130 performs correction to add the voltage value Vβ to the target value (here, Vα) of the charging voltage of the capacitor C10 in the process of S270 that moves from S160. As described above, the target value of the charging voltage of the capacitor C10 is stored in a storage unit (not shown) of the charging control circuit 110, and the microcomputer 130 uses the charging voltage target value Vα stored in the storage unit as Vα + Vβ. Rewrite to Here, this Vβ is set to a predetermined value according to the difference time Tc. Specifically, Vβ is stored in advance in the ROM in association with the difference time Tc. In the process of S270, Vβ is read from the ROM based on the difference time calculated in S130, and the target value Vα of the charging voltage is obtained. Is Vα + Vβ.

  For example, Tb−Ta = Tc> 0, and when the injected fuel is insufficient, Vβ is a positive voltage value. In this case, if the target value of the charging voltage of the capacitor C10 is corrected to Vα + Vβ, the applied voltage applied to the coil 101a increases as compared with the case where the target value of the charging voltage of the capacitor C10 is Vα. The rise of the current value flowing through the coil 101a is increased. That is, the time from when the current starts to flow to the coil 101a until the current value reaches the target current value Ip is shortened as compared with the case where the target value of the charging voltage of the capacitor C10 is Vα. Therefore, the opening timing of the solenoid valve 101 is advanced and the fuel injection amount is increased. Thereby, the fuel injection amount is controlled to an appropriate amount.

  Conversely, when Tb−Ta = Tc <0, and excess fuel is injected, Vβ is a negative voltage value. When the target value of the charging voltage of the capacitor C10 is corrected to Vα + Vβ (Vβ <0), the applied voltage applied to the coil 101a decreases. Therefore, the timing of opening the solenoid valve 101 is delayed and the fuel injection amount decreases. Thereby, the fuel injection amount is controlled to an appropriate amount.

  Here, it demonstrates further using FIG. FIG. 9 shows a time chart when the above-described voltage correction processing is performed when Tb−Ta = Tc> 0. For the INJ1 current I in FIG. 9 (hereinafter simply referred to as current I), the waveform indicated by the wavy line represents the change before the target value of the charging voltage of the capacitor C10 is corrected, and the waveform indicated by the solid line represents the waveform of the capacitor C10. This represents a change after the target value of the charging voltage is corrected to Vα + Vβ. In this example, the current I has reached the target current value Ip at time Tb before correction, but has reached the target current value Ip at time Tb-Tc after correction.

  That is, the arrival time is shortened by the difference time Tc, and the fuel injection amount Qc is secured during the difference time Tc. Therefore, by correcting the target value of the charging voltage of the capacitor C10 to Vα + Vβ, the fuel injection amount becomes an appropriate amount (Qb + Qc). That is, a desired fuel injection amount is ensured.

  In addition, in the case of Tb−Ta = Tc <0, although not shown, the time when the current I reaches the target current value Ip is corrected by correcting the target value of the charging voltage of the capacitor C10 as Vα + Vβ (Vβ <0). Tb + Tc. Then, in this case, the fuel injection amount Qc that has been injected excessively decreases, the fuel injection amount becomes an appropriate amount, and an increase in NOx and PM in the exhaust gas and a deterioration in fuel consumption are prevented. .

Incidentally, in the second embodiment, the processing of S270 is equivalent to compensation means.
In this second embodiment, the fuel injection amount can be corrected without changing the period (energization period) during which the injection command signal S # 1 is high, so the period between the fuel injections Will never be shortened. Therefore, since the charging period of the capacitor C10 is sufficiently secured, each fuel injection is surely performed, and the fuel injection amount is controlled to an appropriate amount so that a desired fuel injection amount is secured. Become.
[Third Embodiment]
Next, the fuel injection control apparatus of 3rd Embodiment is demonstrated. The fuel injection control device of the third embodiment has the same hardware configuration as the fuel injection control device of the first embodiment, and hereinafter, the same reference numerals are used. In the present embodiment, the ECU 100 is provided in the vicinity of the engine block in the engine room.

Moreover, in the following description, although the solenoid valve 101 is demonstrated as an effect | action of this apparatus, it is the same also about the other solenoid valves 102-104.
As described above, the time from when the injection command signal S # 1 becomes high to open the electromagnetic valve 101 until the current I flowing through the coil 101a reaches the target current value Ip (arrival time) is the transistor T12. Alternatively, it varies depending on the response time of the transistor T10 and the ambient temperature of the capacitor C10.

In this type of apparatus, the degree of fluctuation due to the ambient temperature of the capacitor C10 is greater than the degree of fluctuation due to the response time of the transistor T12 or the transistor T10.
Therefore, in the present embodiment, in particular, the fuel injection amount to the engine 1 is corrected by the ambient temperature of the capacitor C10. This will be specifically described below.

In the third embodiment, the microcomputer 130 performs the correction process shown in FIG.
In this correction process, the microcomputer 130 first detects the ECU internal temperature as the ambient temperature of the capacitor C10 (S210).

  Then, it is determined whether or not the detected temperature K1 is within a predetermined setting area. If it is within the setting area (S220: YES), a process of correcting the fuel injection amount to the engine 1 is performed. However, if the detected temperature K1 is not within the predetermined set range (S220: NO), the process for correcting the fuel injection amount to the engine 1 is not performed. The specific contents of the process of S230 will be described later.

  Here, as the setting region used in the determination process of S220, a temperature region in which the arrival time Tb deviates particularly greatly from the theoretical time Ta is set. As a result, in the temperature range where the arrival time Tb does not greatly deviate from the theoretical time Ta and the fuel injection amount does not need to be particularly corrected, the process for correcting the fuel injection amount is not performed. Can be suppressed.

Next, the contents of the process of S230 will be described.
As described above, the arrival time Tb varies depending on the ambient temperature of the capacitor C10. However, the variation amount can be predicted in advance. This is because the ESR of the capacitor C10 can be predicted from the ambient temperature of the capacitor C10. In the third embodiment, when the ECU internal temperature as the ambient temperature is at a specific temperature, a correction time predetermined corresponding to the specific temperature is adjusted with respect to the energization period. It has become.

  FIG. 11 is a graph showing the relationship between the ECU internal temperature and the correction time to be adjusted. Then, the fuel injection amount to the engine 1 is corrected (increased / decreased) by adding or subtracting the correction time calculated in FIG. 11 during the energization period. Further, data representing the relationship of FIG. 11 is stored in advance in a ROM provided in the microcomputer 130. It may be stored in the EEPROM 10 so that it can be easily rewritten.

  When the detected temperature K1 is in the set region (S220: YES), the microcomputer 130 calculates a correction time to be adjusted at the detected temperature K1 from data as shown in FIG. 11 stored in the ROM. At the same time, it increases or decreases with respect to the energization period. As shown in FIG. 11, the correction time that increases or decreases with respect to the energization period is 0 when the ECU internal temperature is 25 ° C., becomes tx when the ECU internal temperature is Tx, and is corrected as the ECU internal temperature is smaller. The time has been extended.

  When the energization period is lengthened, the time when the injection command signal S # 1 becomes low is delayed by the correction time from the time Te, and when the energization period is shortened, the injection command signal S # 1 becomes low. Is set earlier than the time Te by the correction time.

  The time when the injection command signal S # 1 becomes high may be corrected. In this case, in order to lengthen the energization period, the time when the injection command signal S # 1 becomes high is advanced by a correction time from time 0, and in order to shorten the energization period, the injection command signal S # 1 becomes high. This time may be delayed from the time 0 by the correction time. Further, both the time when the injection command signal S # 1 becomes high and the time when it becomes low may be corrected.

  Furthermore, in this apparatus, the presence or absence of abnormality of the water temperature sensor H02 that measures the engine water temperature THW can be detected from the correction time for the energization period in the solenoid valve 101 and the relationship between the ECU internal temperature and the engine water temperature THW. It has become. This will be specifically described below.

  As described above, the microcomputer 130 detects the ECU internal temperature from the temperature sensor H01, and detects the engine water temperature THW from the water temperature sensor H02. When the ECU 100 is provided in the vicinity of the engine block in the engine room as in the third embodiment, if the engine water temperature THW increases, the ECU internal temperature also increases, and conversely the engine water temperature THW decreases. Thus, the engine water temperature THW and the ECU internal temperature are in a proportional relationship such that the ECU internal temperature also decreases. If this proportional relationship does not hold, it can be considered that an abnormality such as a failure has occurred in at least one of the water temperature sensor H02 and the temperature sensor H01.

  Here, FIG. 12 is a graph showing the relationship between the engine coolant temperature THW and the ECU internal temperature. The normal region represents a region in which both are in a proportional relationship, and the abnormal region represents a region in which both are not in a proportional relationship. . That is, in FIG. 12, if the plotted points representing the engine coolant temperature THW and the ECU internal temperature are in the normal region, it can be said that the temperature sensor H01 and the water temperature sensor H02 are normal, but the plotted points are in regions other than the normal region. In some cases, it can be said that at least an abnormality has occurred in either the temperature sensor H01 or the water temperature sensor H02.

In the latter case, it cannot be specified which of the temperature sensor H01 and the water temperature sensor H02 is abnormal.
Therefore, in the third embodiment, when the proportional relationship is lost, the microcomputer 130 uses the arrival time Tb data for the solenoid valve 101 to check whether there is an abnormality in the temperature sensor H01 or the water temperature sensor H02. Judge about. Specifically, the microcomputer 130 executes the abnormality determination process shown in FIG. This abnormality determination process is executed at regular time intervals.

  In this abnormality determination process, the microcomputer 130 first determines whether or not the relationship between the detected value of the engine coolant temperature THW and the detected value of the ECU internal temperature is proportional (S310), and determines that it is proportional. (S310: YES), the process returns to the predetermined process as it is, but if it is determined that there is no proportional relationship (S310: NO), the arrival time is detected (S320). Then, the ECU internal temperature is estimated from the detected arrival time Tb (S330).

  As described above, for example, when the ambient temperature of the capacitor C10 decreases, the arrival time increases, and conversely, when the ambient temperature increases, the arrival time decreases. Between the ambient temperature of the capacitor C10 and the arrival time, for example. Have a certain relationship. And if one value is known about the ambient temperature and arrival time of the capacitor | condenser C10, the other value can also be estimated now.

  In this apparatus, data representing the relationship between the ambient temperature of the capacitor C10 and the arrival time is stored in advance in a ROM or the like included in the microcomputer 130, and the ambient temperature of the capacitor C10 is calculated based on the above data from the arrival time Tb. It has become.

  Then, the microcomputer 130 compares the detected ECU internal temperature with the estimated ambient temperature, and determines whether or not both can be regarded as the same value (S340). For example, if the difference between the two is within a certain range, it is regarded as the same value, and if the difference between the two is not within the certain range, it can be determined that the difference is not the same. If it is determined that both values can be regarded as the same value (S340: YES), it is determined that an abnormality has occurred in the water temperature sensor H02 (S350), and a warning that an abnormality has occurred in the water temperature sensor H02 is issued (S360). . For example, it is conceivable to turn on a warning lamp that notifies that an abnormality has occurred in the water temperature sensor H02. Further, a warning may be given by voice or the like.

  On the other hand, if it is determined that the detected ECU internal temperature and the estimated ambient temperature are not the same value (S340: NO), it is determined that an abnormality has occurred in at least one of the temperature sensor H01 and the water temperature sensor H02, and S360 Move on to processing. In S360 in this case, a warning is given that an abnormality has occurred in at least one of the water temperature sensor H02 and the temperature sensor H01 (S360). For example, it is conceivable to turn on a warning lamp that informs that an abnormality has occurred in the water temperature sensor H02 or the temperature sensor H01. Further, a warning may be given by voice or the like.

  Here, in the third embodiment, the correction time corresponding to the ambient temperature is adjusted with respect to the energization period according to the ambient temperature of the capacitor C10. The target value of the charging voltage of the capacitor C10 may be increased or decreased depending on the ambient temperature.

  In this case, the lower the ambient temperature of the capacitor C10, the higher the target value of the charging voltage value of the capacitor C10. When the ambient temperature of the capacitor C10 is small, the ESR of the capacitor C10 increases and the voltage applied to the coil 101a decreases, so the fuel injection amount to the engine 1 decreases. Then, if it correct | amends so that the target value of the charging voltage value of the capacitor | condenser C10 may be made high, since the applied voltage to the coil 101a will increase, it can increase a fuel injection amount and can be made into an appropriate amount.

  On the other hand, when the ambient temperature of the capacitor C10 is high, the fuel injection amount to the engine 1 increases, so that the target value of the charging voltage value of the capacitor C10 is corrected to be low. As a result, the fuel injection amount can be reduced so that excess fuel is not injected.

  Further, since the ambient temperature of the capacitor C10 and the engine coolant temperature THW are in a proportional relationship, the fuel injection amount may be corrected according to the engine coolant temperature THW. That is, the energization period may be increased or decreased according to the engine coolant temperature THW, or the target value of the charging voltage may be increased or decreased.

  In this case, the energization period is corrected so that the energization period becomes longer as the engine coolant temperature THW is lower, and the energization period is corrected as the engine coolant temperature THW is higher. As for the target value of the charging voltage, the target value of the charging voltage is increased as the engine coolant temperature THW is lower, and the target value of the charging voltage is decreased as the engine coolant temperature THW is higher.

In the present embodiment, the water temperature sensor H02 corresponds to the water temperature detection means, the processing in S310 corresponds to the proportional determination means, the processing in S340 and S350 corresponds to the abnormality determination means, and the EEPROM 10 serves as the temperature region storage means. It corresponds. The microcomputer 130, when correcting the target value of the case, and charging voltage for correcting the conduction period Te smell corresponds to compensation means.

  According to the third embodiment, by performing a relatively simple process of adjusting the correction time to the energization period according to the ambient temperature of the capacitor C10, the fuel injection amount can be appropriately controlled, and the desired fuel can be controlled. The injection amount can be ensured.

Further, in a temperature range where the fuel injection amount does not vary greatly from an appropriate amount, the process for correcting the fuel injection amount is not performed, so that the load on the apparatus is not increased.
Further, it is convenient to detect the presence or absence of abnormality of the temperature sensor H01, and consequently the presence or absence of abnormality of the water temperature sensor H02. And since it is not necessary to provide the mechanism for detecting the presence or absence of abnormality of the water temperature sensor H02, it is advantageous in terms of cost. Further, even when an abnormality occurs in the temperature sensor H01, the fuel injection amount can be corrected according to the engine water temperature THW detected by the water temperature sensor H02, so that a desired fuel injection amount can be ensured more reliably. can do.

  As a mechanism for detecting whether or not the water temperature sensor H2 is abnormal, a mechanism using a timer (hereinafter referred to as a soak timer) that counts the stop period of the microcomputer 130 can be considered. Specifically, the microcomputer 130 detects the engine coolant temperature THW immediately before the microcomputer 130 is stopped and immediately after the microcomputer 130 is started. The stop period of the microcomputer 130 is counted by the soak timer, and the microcomputer 130 also reads the count value of the soak timer immediately after activation. Then, the engine water temperature THW immediately after startup should decrease as the count value of the soak timer (that is, the stop period of the microcomputer 130) increases as seen from the engine water temperature THW immediately before the stop, and the engine water temperature immediately before the stop. If the count values of THW and the soak timer are known, the microcomputer 130 can estimate the engine coolant temperature THW immediately after startup. Therefore, the microcomputer 130 compares the estimated value with the actually detected value for the engine water temperature THW immediately after startup, and if it is determined that they differ by a certain value or more, the water temperature sensor H02 is abnormal. judge.

And according to this 3rd Embodiment, even if it does not provide the mechanism using such a soak timer separately, the presence or absence of abnormality of the water temperature sensor H02 can be detected.
[Fourth Embodiment]
Next, a fuel injection control device according to a fourth embodiment will be described.

  FIG. 14 is a configuration diagram of the fuel injection device according to the fourth embodiment. In the fourth embodiment, piezo injectors P101, P102, P103, and P104 are provided instead of the solenoid valves 101 to 104. The piezo injectors P101 to P104 are charged by discharging the capacitors C10 and C20. When the charging voltage reaches a specified value, pistons (not shown) inside the piezo injectors P101 to P104 are driven.

  In order to prevent an overcurrent from flowing when the capacitors C10 and C20 are discharged, the inductor L13 is connected to the energizing path between the transistor T12 and the terminal COM1, and the energizing path between the transistor T22 and the terminal COM2 is connected. Is connected to an inductor L23.

  Furthermore, in this apparatus, transistors T13 and T23 for discharging the piezo injectors P101 to P104 are provided. The transistor T13 has one output terminal connected to the energization path between the transistor T12 and the terminal COM1, and the other output terminal connected to the ground line. The transistor T23 has one output terminal connected to the energization path between the transistor T22 and the terminal COM2, and the other output terminal connected to the ground line.

  Hereinafter, the operation of this apparatus will be briefly described with reference to FIG. Here, the piezo injector P101 will be described, but the same applies to the other piezo injectors P102 to P104.

  First, predetermined energy is stored in the capacitor C10 in advance. When the injection command signal S # 1 for the piezo injector P101 becomes high (time 0), the transistor T10 is turned on, and further, although not shown, the transistor T12 is turned on / off. Then, the capacitor C10 is discharged, and the discharge energy is stored in the piezo injector P101 as shown in the charging period of FIG.

  The piezo injector P101 is provided with a piezoelectric element for driving the piston. When the charging voltage reaches the specified value Vp in the piezo injector P101, the piezoelectric element is deformed to drive the piston. As a result, fuel is injected into the engine 1.

  When a predetermined energization period has elapsed and the injection command signal S # 1 becomes low (time Te), the transistor T10 is turned off and the transistor T12 is also turned off. Further, the transistor T13 is turned on / off, and the piezo injector P101 is discharged. Then, the deformed state of the piezoelectric element is released, the piston returns to the original position, and fuel injection is stopped.

  In the fourth embodiment, the ambient temperature of the capacitor C10 is detected, and the energization period (high period of the injection command signal S # 1) is corrected according to the ambient temperature, whereby the fuel injection amount to the engine 1 is corrected. Increase or decrease. Specifically, the microcomputer 130 performs the same processing of FIG. 10 as in the third embodiment.

  That is, the ECU internal temperature is detected as the ambient temperature of the capacitor C10 (S210), and when the ambient temperature is in a predetermined setting region (S220: YES), the correction time calculated according to the ambient temperature is set as the energization period. (S230). The energization period is longer as the ambient temperature is lower and shorter as the ambient temperature is higher.

  This is because when the ambient temperature is low, the ESR of the capacitor C10 increases and the discharge energy decreases, and therefore, in the piezo injector P101, the charging period shown in FIG. 15 becomes longer and the fuel injection amount decreases. The energizing period is made longer. On the other hand, when the ambient temperature is high, the fuel injection amount is increased, so that the energization period is shortened.

  When the energization period is lengthened, the time when the injection command signal S # 1 becomes low is delayed by the correction time from the time Te, and when the energization period is shortened, the injection command signal S # 1 becomes low. Is set earlier than the time Te by the correction time.

  The time when the injection command signal S # 1 becomes high may be corrected. In this case, in order to lengthen the energization period, the time when the injection command signal S # 1 becomes high is advanced by a correction time from time 0, and in order to shorten the energization period, the injection command signal S # 1 becomes high. This time may be delayed from the time 0 by the correction time. Further, both the time when the injection command signal S # 1 becomes high and the time when it becomes low may be corrected.

  As another embodiment, the target value of the charging voltage of the capacitor C10 may be increased or decreased according to the ambient temperature. In this case, the target value of the charging voltage is increased as the ambient temperature is lower, and the target value of the charging voltage is decreased as the ambient temperature is higher. Then, the correction amount (increase / decrease amount) of the target value of the charging voltage may be stored in advance in the ROM or the like in association with the ambient temperature. That is, the increase / decrease amount corresponding to the ambient temperature is read from the ROM or the like.

  When the target value of the charging voltage of the capacitor C10 is increased, the time from when the voltage is applied to the piezo injector P101 until the piezo injector P101 is opened (the charging period in FIG. 15) is shortened, and the valve opening timing is increased. The fuel injection amount can be increased early. Further, when the target value of the charging voltage of the capacitor C10 is lowered, the charging period can be lengthened to delay the valve opening timing, and the fuel injection amount can be reduced.

According to the fuel injection control device of the fourth embodiment, even when the piezo injectors P101 to P104 are controlled, the fuel injection amount is controlled to an appropriate amount so that a desired fuel injection amount is ensured. Can do. In addition, a relatively simple process of correcting the fuel injection amount according to the ambient temperature of the capacitor C10 may be performed, which is advantageous in that the load on the apparatus can be suppressed.
[Fifth Embodiment]
Next, a fuel injection device according to a fifth embodiment will be described.

  As described above, in FIG. 1, the fuel pumped from the high pressure fuel pump 3 is accumulated in a high pressure state by the common rail 4, and the fuel is supplied from the common rail 4 to the electromagnetic valves 101 to 104 provided in each cylinder. It has become. Then, the ECU 100 controls the high-pressure fuel pump 3 to control the fuel pressure accumulated in the common rail 4.

  In particular, in the fuel injection control device of the fifth embodiment, the pressure of the fuel accumulated in the common rail 4 is further corrected according to the above-described difference time Tc. Specifically, the pressure of the fuel accumulated in the common rail 4 is corrected so as to increase as the difference time Tc increases in the positive direction, while the common rail 4 increases as the difference time Tc increases in the negative direction. The fuel pressure accumulated in is corrected so as to be small. Here, the correction amount (pressure increase / decrease amount) is stored in advance in a ROM or the like in association with the difference time Tc. In this apparatus, the correction amount is read from the ROM based on the difference time Tc. The microcomputer 130 controls the high-pressure fuel pump 3 according to the correction amount, and corrects the fuel pressure accumulated in the common rail 4.

  Thereby, the fuel injection amount to the engine 1 is set to an appropriate amount. This is because the amount of fuel injected into the cylinder 2 per unit time increases as the pressure of fuel accumulated in the common rail 4 increases, and conversely, as the pressure of fuel accumulated in the common rail 4 decreases. This is because the amount of fuel injected into the cylinder 2 in a certain unit time decreases.

  That is, if the difference time Tc is large in the positive direction, the fuel injection amount may be insufficient. In this case, the fuel injection amount is increased by increasing the pressure of the fuel accumulated in the common rail 4. To. Further, if the difference time Tc is large in the negative direction, it is considered that excess fuel is injected. In this case, the fuel pressure accumulated in the common rail 4 is reduced to reduce the fuel injection amount. To.

Thus, in this apparatus, the fuel injection amount to the engine 1 is controlled to an appropriate amount by controlling the pressure of the fuel accumulated in the common rail 4.
In the present fifth embodiment, the microcomputer 130, to together to correspond to the pressure control means corresponds to the compensation means.

And in this 5th Embodiment, you may make it correct | amend said pressure according to the ambient temperature of the capacitor | condenser C10. In this case, the pressure correction amount may be stored in the ROM or the like in association with the ambient temperature. Moreover, when correcting a pressure according to ambient temperature, the piezoelectric injectors P101-P104 may be used instead of the solenoid valves 101-104. Then, in a case of correcting the pressure of the fuel accumulated in the common rail 4 according to the ambient temperature, the microcomputer 130 corresponds to the compensation means.

  According to the fifth embodiment, since the energization period of the solenoid valves 101 to 104 is not adjusted, the period between each fuel injection is ensured and the capacitor C10 is reliably charged. Therefore, it is possible to provide a fuel injection control device that ensures fuel injection and ensures that a desired fuel injection amount is secured by controlling the fuel injection amount to an appropriate amount.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various form can be taken within the technical scope of this invention.
For example, in the above embodiment, the fuel injection control system for a diesel engine has been described. However, the present invention may be applied to a fuel injection control system for a gasoline engine.

  Moreover, in the said embodiment, as a method of correct | amending fuel injection quantity, (1) The method to increase / decrease an energization period, (2) The method to increase / decrease the target value of the charging voltage of capacitor | condenser C10, C20, and (3) Common rail 4 Although the method of increasing or decreasing the pressure of the fuel accumulated in the above has been described, they can be implemented in combination as appropriate.

  Further, in the energization period correction process or the voltage correction process, after the ECU internal temperature is detected in S140, if it is determined that the ECU internal temperature is within a predetermined setting region, the process proceeds to the next step S150. Also good. And when it determines with ECU internal temperature not being in a setting area | region, what is necessary is just to complete | finish an energization period correction process.

It is a block diagram of a fuel injection control system. It is a block diagram of a fuel-injection control apparatus. It is a time chart explaining operation | movement of a fuel-injection control apparatus. It is a flowchart showing the flow of an energization period correction process. It is a time chart explaining an example of operation of a fuel injection control device. It is a time chart explaining an example of an operation of a fuel injection control device. (Part 1) It is a time chart explaining an example of an operation of a fuel injection control device. (Part 2) It is a flowchart showing the flow of a voltage correction process. It is a time chart explaining an example of an operation of a fuel injection control device. (Part 3) It is a flowchart showing the flow of a correction process. It is a graph showing the relationship between ambient temperature and correction time. It is explanatory drawing explaining the relationship between ECU internal temperature and engine water temperature. It is a flowchart showing the flow of abnormality determination processing. It is a block diagram of the fuel-injection control apparatus of 4th Embodiment. It is a time chart explaining operation | movement of the fuel-injection control apparatus of 4th Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, 3 ... High pressure fuel pump, 4 ... Common rail, 5 ... Injector, 8 ... Pressure sensor, 10 ... EEPROM, 50 ... Booster circuit, 100 ... Electronic control unit (ECU), 101-104 ... Solenoid valve, 101a- 104a ... Coil, 110 ... Charge control circuit, 120 ... Drive control circuit, 130 ... Microcomputer, C10, C20 ... Capacitor, COM1, COM2 ... Terminal, D11, D21, D13, D23, D31, D32 ... Diode, H01 ... Temperature sensor , H02: Water temperature sensor, INJ1-INJ4 ... Terminal, L00 ... Inductor, Lp ... Power line, P101-P104 ... Piezo injector, R00, R01, R02, R10, R20 ... Resistance, S # 1-S # 4 ... Injection command Signal, T10 to T40, T11, T21, T12, T22... Transistor, V ... the battery voltage.

Claims (9)

A high voltage generating means that has a capacitor and generates a high voltage of a predetermined voltage value higher than the power supply voltage by charging the capacitor;
An injector that opens by discharging from the capacitor and injects fuel into the internal combustion engine;
Setting means for setting a drive period of the injector;
A switching element that is provided in a current-carrying path of the injector and discharges from the capacitor to the injector by turning on;
Discharge control means for outputting an ON command for turning on the switching element to the switching element at the start timing of the driving period set by the setting means;
In a fuel injection control device comprising:
An arrival time measuring means for measuring an arrival time from when the ON command is output until the discharge current from the capacitor flowing through the injector reaches a specified value;
A difference time detecting means for detecting a difference time obtained by subtracting a predetermined specified arrival time from the arrival time measured by the arrival time measuring means;
As a correction process for increasing / decreasing the fuel injection amount to the internal combustion engine according to the difference time , at least the start timing of the drive period set by the setting means is set according to the difference time. Correction means for performing correction so as to be faster as the difference is larger in the positive direction, and to be delayed as the difference time is larger in the negative direction ;
A fuel injection control device comprising: The fuel injection control device according to claim 1,
After the injector is opened, holding means for holding the valve open state,
The correction means, as the correction process, increases a holding period in which the holding means holds the injector in a valve-open state as the difference time increases in the positive direction according to the difference time. The shorter is the larger in the negative direction,
A fuel injection control device. In the fuel injection control device according to claim 1 or 2,
The correction means increases , as the correction process, the charging voltage of the capacitor by the high voltage generation means as the difference time increases in the positive direction according to the difference time , and the difference time is in a negative direction. To decrease the bigger the ,
A fuel injection control device. The fuel injection control device according to any one of claims 1 to 3,
Pressure control means for controlling the fuel supply pressure to the injector;
As the correction process, the correction unit increases the supply pressure controlled by the pressure control unit according to the difference time as the difference time increases in the positive direction, and the difference time in the negative direction. Decrease the larger,
A fuel injection control device. The fuel injection control device according to any one of claims 1 to 4,
The correction means determines whether or not the difference time is within a predetermined range. If the difference time is not within the predetermined range, the correction processing is not performed . The fuel injection control device according to any one of claims 1 to 5,
Temperature detecting means for detecting the ambient temperature of the capacitor;
Said correction means, said ambient temperature detected by said temperature detecting means is operable to determine whether a particular temperature range, when in a specific temperature range, which is the correction processing as intends row A fuel injection control device. The fuel injection control device according to claim 6 , wherein
The fuel injection control device is provided in the vicinity of the internal combustion engine, and the ambient temperature of the condenser and the cooling water temperature of the internal combustion engine are in a proportional relationship,
Water temperature detecting means for detecting the cooling water temperature;
A cooling water temperature detected by the water temperature detecting means (hereinafter referred to as a detected water temperature in this section) and an ambient temperature of the capacitor detected by the temperature detecting means (hereinafter referred to as a detected ambient temperature in this section). Proportional determination means for determining whether or not the proportional relationship exists;
When it is determined by the proportional determination means that the detected water temperature and the detected ambient temperature are not in the proportional relationship, the ambient temperature of the capacitor is estimated from the difference time, and the estimated ambient temperature of the capacitor and the estimated temperature An abnormality determination unit that determines that an abnormality has occurred in the water temperature detection unit when both of the detected ambient temperature are compared and can be regarded as the same value;
The fuel injection control apparatus characterized by comprising a. The fuel injection control device according to claim 5 , wherein
A fuel injection control apparatus comprising: a non-volatile time range storage means for rewriting and storing the predetermined range used by the correction means for determining the difference time . In the fuel injection control device according to claim 6 or 7 ,
A fuel injection control apparatus comprising: a non-volatile temperature region storage unit that rewritably stores the specific temperature region used by the correction unit for determining the ambient temperature .

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