DE102014216521B4 - Boost power supply device - Google Patents

Abstract

Boost power supply device, which is arranged in a control device (31) that drives an injector (41) for injecting fuel into an internal combustion engine of a vehicle, the injector (41) being designed to prevent mechanical vibration caused by the internal combustion engine is transmitted to the injector (41), affects an operation of a valve body, the booster power supply device comprising: an output capacitor (34) that accumulates electric power that is discharged to an injector opening electric load (41a) for opening the injector (41); a Charging circuit (35) that boosts a battery voltage (VB) of the vehicle and charges the output capacitor (34); anda charging control circuit (36) which controls the charging circuit (35) such that a charging voltage for the output capacitor (34) becomes equal to a target voltage, the output capacitor (34) including a plurality of capacitors (C0, C1) connected in parallel which A boost power supply apparatus further comprises: a capacitance setting switch (T1) connected in series with a capacitor (C1) other than a particular one of the capacitors (C0, C1); anda switching device (38, S110 to S270, S310 to S340) which controls turning on and off of the capacitance setting switch (T1), the capacitance setting switch (T1) having the one capacitor (C1) connected in series with the capacitance setting switch (T1) , switches in parallel with the special capacitor (C0) when the capacitance setting switch (T1) is turned on, and wherein the capacitance setting switch (T1) interrupts the connection of the one capacitor (C1) connected in series with the capacitance setting switch (T1) and one electrostatic capacitance of the output capacitor (34) is reduced when the capacitance setting switch (T1) is turned off.

Description

The present invention relates to a booster power supply device disposed in a control device that drives an injector.

A control device that drives an injector that injects fuel into the internal combustion engine of a vehicle is equipped with a voltage converter. The voltage converter boosts the battery voltage of the vehicle in order to charge a capacitor, thereby causing the charging voltage of the capacitor to be equal to a target voltage which is higher than the battery voltage. This type of control device discharges the capacitor of the voltage converter to the coil of the injector when a drive operation of the injector is started, thereby promoting the opening of the injector (see for example JP 2009 - 22 139 A ).

For internal combustion engines mounted in vehicles, there is a technology for achieving highly efficient combustion to reduce emission: fuel injection from an injector is performed more than once during a fuel injection period of a cylinder (e.g., compression stroke to combustion stroke). This technology is known, for example, as multi-stage injection and also as closed injection.

In a control device that performs this multi-stage injection, it is necessary to energize (charge) the coil of an injector more than once in a short time. For this reason, the electrostatic capacity (hereinafter also simply referred to as capacity) of a capacitor of a voltage converter is set to a large value, so that the following can be carried out: Fuel injection is carried out a predetermined number of times within a predetermined time even, for example, without errors when not charging.

In a voltage converter, the charging time (hereinafter also referred to as the necessary charging time), which is necessary so that the charging voltage of a capacitor is equal to a target voltage, increases with an increase in the capacitance of the capacitor. For this reason, when the capacitance of a capacitor is constantly large, the charging voltage of the capacitor may be insufficient in some cases.

For example, the required charging time is also increased when the battery voltage is low. For this reason, the following can happen if the capacity of a capacitor is large: If the battery voltage drops, for example when the internal combustion engine is started, the required charging time increases further. As a result, the charging is too late and the charging voltage cannot reach the target voltage when the fuel injection is started. When this happens, the target voltage cannot be supplied to the coil of the injector and the opening of the injector is delayed, and this leads to a deterioration in the control accuracy of the fuel injection (in particular, a reduction in the injection amount).

The EP 2 015 431 B1 discloses a boost power supply device disposed in a control device that drives an injector to inject fuel into an internal combustion engine of a vehicle, the boost power supply device comprising: an output capacitor that accumulates electrical energy discharged to an injector electrical port load for opening the injector; a charging circuit that boosts a battery voltage of the vehicle and charges the output capacitor; and a charge control circuit that controls the charge circuit so that a charge voltage for the output capacitor becomes equal to a target voltage. The charging voltage is adjusted by switching a coil on and off.

The JP H11-289766 A describes a power supply circuit having a coil which is connected in series with an alternating current source and can be short-circuited with a coil switch connected in parallel with the coil, and a capacitor switch connected in series with a smoothing capacitor. The smoothing capacitor is one of several capacitors connected in parallel.

In view of this, it is an object of the present invention to provide a booster power supply device disposed in a control device that drives an injector. The booster power supply device prevents delay of opening of an injector caused when charging of a capacitor to a target voltage is performed too late.

According to one aspect of the present invention, there is provided a booster power supply device disposed in a control device that drives an injector for injecting fuel into an internal combustion engine of a vehicle, the injector preventing mechanical vibration from being transmitted from the internal combustion engine to the injector becomes, affects an operation of a valve body, the booster power supply device including: an output capacitor that accumulates electrical energy that is discharged to an injector electrical opening load for opening the injector; a charging circuit that boosts a battery voltage of the vehicle and charges the output capacitor; and a charge control circuit that controls the charge circuit such that a charge voltage for the output capacitor is equal to a target voltage. The output capacitor contains several capacitors that are connected in parallel to one another. The boosting power supply device also includes a capacitance setting switch connected in series with a capacitor other than a particular one of the capacitors; and a switching device that controls turning on and off of the capacity setting switch. The capacitance setting switch connects the one capacitor connected in series with the capacitance setting switch in parallel with the special capacitor when the capacitance setting switch is turned on. The capacitance adjusting switch interrupts the one capacitor (in other words, interrupts the connection of the charge / discharge path for the output capacitor) connected in series with the capacitance adjusting switch, and reduces an electrostatic capacitance of the output capacitor when the capacitance adjusting switch is turned off.

In this booster power supply device, the following can be performed by means of the switching device that turns off the capacitance setting switch: The electrostatic capacitance of the output capacitor can be decreased to shorten the charging time required for the charging voltage of the output capacitor to become equal to a target voltage. Therefore, the following can be prevented: Charging of the output capacitor to a target voltage occurs too late and opening of an injector is delayed.

• 1 ein schematisches Diagramm, das eine Kraftstoffeinspritzsteuervorrichtung gemäß einer ersten Ausführungsform darstellt;
• 2 eine Zeichnung zur Erläuterung des Betriebs einer Antriebssteuerschaltung;
• 3 ein Flussdiagramm eines ersten Bestimmungsprozesses gemäß der ersten Ausführungsform;
• 4 ein Flussdiagramm eines zweiten Bestimmungsprozesses gemäß der ersten Ausführungsform;
• 5 ein Flussdiagramm eines dritten Bestimmungsprozesses gemäß der ersten Ausführungsform;
• 6 ein Flussdiagramm eines vierten Bestimmungsprozesses gemäß der ersten Ausführungsform;
• 7 ein Flussdiagramm eines fünften Bestimmungsprozesses gemäß der ersten Ausführungsform;
• 8 ein Flussdiagramm eines Kapazitätswiederherstellungsprozesses gemäß der ersten Ausführungsform;
• 9 eine Zeichnung zur Erläuterung eines Problems; und
• 10 ein Flussdiagramm eines Kapazitätswiederherstellungsprozesses gemäß einer zweiten Ausführungsform.

The above and other objects, features and advantages of the present invention will become apparent from the following detailed description with reference to the accompanying drawings. Show it:

• 1 Fig. 3 is a schematic diagram illustrating a fuel injection control device according to a first embodiment;
• 2 a drawing for explaining the operation of a drive control circuit;
• 3 a flowchart of a first determination process according to the first embodiment;
• 4th a flowchart of a second determination process according to the first embodiment;
• 5 a flowchart of a third determination process according to the first embodiment;
• 6th a flowchart of a fourth determination process according to the first embodiment;
• 7th a flowchart of a fifth determination process according to the first embodiment;
• 8th a flowchart of a capacity recovery process according to the first embodiment;
• 9 a drawing for explaining a problem; and
• 10 a flowchart of a capacity recovery process according to a second embodiment.

In the following, a fuel injection control device according to various embodiments will be described with reference to the drawings.

The fuel injection control apparatus according to the embodiments drives four solenoid injectors, each of which injects fuel into individual cylinders # 1 to # 4 of a multi-cylinder internal combustion engine (four cylinders in this example) mounted in a vehicle. The energization start timing and energization time for the coil of each injector are controlled to control the timing and injection amounts of fuel injection into the individual cylinders # 1 to # 4. According to the embodiments, transistors used as switching elements are, for example, MOSFETs, but other types of transistors such as bipolar transistors and IGBTs (Insulated Gate Bipolar Transistors) can also be used.

First embodiment

Like it in 1 As shown, an electronic control unit (hereinafter referred to as ECU) 31 as a fuel injection control device includes a terminal CM to which one end (upstream side) of the coil 41a an injector to be driven 41 connected is; a terminal INJ to which the other end (downstream side) of the coil 41a connected is; a transistor T10 whose output port is connected to the INJ port; and a current detection resistor R10 that is between the other output terminal of the transistor T10 and a ground line is connected.

In the injector 41 fuel injection is performed or stopped as described below. When the coil 41a is excited as a valve-opening electric load, the valve body (so-called nozzle needle), which is not shown, is moved (in other words, raised) to the valve-opening position, and fuel injection is performed; and when the energization of the coil 4e1a is stopped, the valve body returns to the original valve closing position and the fuel injection stops.

1 shows only one injector 41 corresponding to the n-th cylinder #n (n is a number from 1 to 4) of the four injectors 41 , and the following description will be made of the driving of the one injector 41 . In fact, the connection CM is a common connection for the injectors 41 the individual cylinder, and the coil 41a of a respective injector 41 is connected to the connection CM. The INJ connection and the transistor T10 are for each injector 41 present (in other words, for each cylinder). The transistor T10 is a switching element for selecting an injector to be driven 41 (in other words, a cylinder to be injected with fuel) and is designed as a cylinder selection switch.

The ECU 31 contains a transistor T11 as a constant current switching element, an output terminal of which is connected to a power supply line Lp through which a battery voltage (the voltage of a vehicle battery) VB is supplied as a supply voltage; a backflow prevention diode D11 whose anode connects to the other output terminal of the transistor T11 is connected and the cathode of which is connected to the terminal CM; a current feedback diode D12 whose anode is connected to a ground line and whose cathode is connected to the terminal CM; and a voltage converter 33 .

When the user of the vehicle performs a predetermined ignition switch-on operation, the power supply line Lp is supplied with the battery voltage VB. Examples of the ignition-on operation include turning a key inserted into the ignition key cylinder to the ignition-on position, pressing a start button, and the like.

When the transistor T10 is turned on and the transistor turned on T11 is switched off, the diode leads D12 a current to the coil 41a back.

The voltage converter 33 is a boost DC / DC converter and contains an output capacitor 34 , in which electrical energy is accumulated, which is sent to the coil 41a is discharged, a transistor T1 as a capacitance adjusting switch for adjusting the electrostatic capacitance of the output capacitor 34 , a charging circuit 35 that the battery voltage VB for charging the output capacitor 34 amplified, and a charge control circuit 36 who have favourited the charging circuit 35 operates so that the charging voltage of the output capacitor 34 becomes equal to a target voltage.

The charging circuit 35 contains a coil L0 , an amplification transistor T0 , a backflow prevention diode D0 and a current detection resistor R0 .

The sink L0 has one end connected to the power supply line Lp and another end connected to an output terminal (drain) of the transistor T0 connected is. The resistance R0 is between the other output terminal (source) of the transistor T0 and a ground line is connected. The anode of the diode D0 is with the connection point between the coil L0 and the transistor T0 connected.

The output capacitor 34 consists of several (in this example two) capacitors C0 and C1 that are connected in parallel to each other. One end (positive pole) of the respective capacitors C0 and C1 is with the cathode of the diode D0 connected. The capacitors C0 and C1 are for example aluminum electrolytic capacitors, but can also be one type of capacitor.

The other end (negative pole) of the capacitor C0 is to the connection point between the transistor T0 and the resistance R0 connected. The transistor T1 is in series with the other end (negative pole) of the capacitor C1 switched; and the output terminal (source) of the transistor T1 on the opposite side of the capacitor C1 is to the connection point between the transistor T0 and the resistance R0 connected.

When the transistor T1 is turned on, the capacitor becomes C1 in parallel with the capacitor C0 switched. When the transistor T1 is turned off, the connection of the capacitor C1 interrupted with the charge / discharge path. Therefore, the following takes place when the electrostatic capacity of the capacitor C0 "Cap0" is and the electrostatic capacity of the capacitor C1 "Cap1" is: If the transistor T1 is turned on, the electrostatic capacity of the output capacitor becomes 34 equal to "Cap0 + Cap1"; and if the transistor T1 is switched off, the electrostatic capacity is reduced 34 of the output capacitor 34 to "Cap0".

In the voltage converter 33 the following takes place when the transistor T0 is turned on and off: There is a flyback voltage (back electromotive voltage) larger than the battery voltage VB at the connection point between the coil L0 and the transistor T0 generated; and the output capacitor 34 (more precisely C0 and / or C1) is caused by this flyback voltage across the diode D0 loaded. Because of this, the output capacitor becomes 34 charged with a voltage higher than the battery voltage VB.

The charge control circuit 36 is activated when a charge permission signal is received by the circuit 36 is supplied, has an active level, and it switches the transistor T0 on and off so that the following happens: The voltage VC on the positive pole of the output capacitor 34 (C0, C1) becomes equal to a preset target voltage (> VB). (This voltage VC is also the charging voltage of the output capacitor 34 and is also referred to as capacitor voltage in the following.)

The charge control circuit 36 monitors the capacitor voltage VC and also monitors the charging current of the output capacitor 34 based on the voltage across the resistor R0 arises. This will make the transistor T0 turned on and off, so the output capacitor 34 is loaded with an efficient cycle. When the capacitor voltage VC reaches the target voltage, the charge control circuit stops 36 the transistor T0 turned off to the charging of the output capacitor 34 to stop. Because of this, the output capacitor becomes 34 charged so that the capacitor voltage VC, which is its charging voltage, becomes equal to the target voltage.

The ECU 31 also contains a transistor T12 as a discharge switching element, which is the positive pole of the output capacitor 34 connects to terminal CM, an energy recovery diode D13 whose anode is connected to the INJ connection and whose cathode is connected to the positive pole of the capacitor C0 is connected, a drive control circuit 37 who have favourited the transistors T10 , T11 and T12 controls and thereby a current flowing through the coil 41a flows, controls, a microcomputer 38 and a power supply circuit 39 .

The power supply circuit 39 For example, the battery voltage VB is supplied from the power supply line Lp, and it generates and outputs a certain supply voltage Vcc (for example, 5 V) from the supplied battery voltage VB. The microcomputer 38 is connected to the supply voltage Vcc from the power supply circuit 39 operated. The power supply circuit 39 has a power-on reset function that the microcomputer 38 resets continuously for a certain period of time after the output of the supply voltage Vcc has started.

The microcomputer 38 contains a CPU 51 that runs programs, a ROM 52 in which programs, fixed data and the like are stored, a RAM 53 in which the results of the calculation of the CPU 51 and the like are stored, an A / D converter (ADC) 54 and similar.

The microcomputer 38 generates an injection command signal for the respective cylinders based on engine operating information such as an engine speed NE, an accelerator opening (accelerator opening) ACC, and an engine water temperature THW detected by various sensors (not shown). He then gives the signal to the drive control circuit 37 out. The injection command signal means the coil 41a of the injector 41 only when the signal is at an active level (HIGH in this embodiment) to excite, in other words, the injector 41 to open.

The microcomputer 38 performs the following processing when the injection command signals for the individual cylinders are all low (that is, when the fuel injection is not performed): it brings a charge permission signal to the charge control circuit 36 to an active level so that the capacitor voltage VC becomes equal to the target voltage.

The active level of the charge permission signal is, for example, a low level, and the microcomputer 38 brings the charge permission signal to the active level (LOW) from the above power reset timing on. Not just the microcomputer 38 but also the charge control circuit 36 and the drive control circuit 37 are operated using the battery voltage VB from the power supply line Lp as a power source. Because of this, the output capacitor becomes 34 from the time when the battery voltage VB is supplied to the power supply line Lp and the ECU 31 is started in the voltage converter 33 charged so that the capacitor voltage VC becomes equal to the target voltage.

The following is a description of the operation of the drive control circuit 37 regarding 2 .

Like it in 2 is shown, the drive control circuit performs 37 following processing when the injection command signal S # n for the n-th cylinder #n received from the microcomputer 38 output goes high: it holds the transistor T10 for the injector 41 of the n-th cylinder #n is turned on while the injection command signal S # n is high. When the injection command signal S # n becomes high, the drive control circuit switches 37 also the transistor T12 a.

As a result, the connection becomes the positive pole of the output capacitor 34 connected to the terminal CM, and the output capacitor 34 discharges its energy to the coil 41a . This discharge starts energizing the coil 41a .

After the transistor T12 has been switched on, the drive control circuit detects 37 the current flowing through the coil 41a flows, based on the voltage across the resistor R10 is applied. (The current flowing through the coil 41a flows, is also the drive current of the injector 41 and is hereinafter also referred to as coil current.) When the drive control circuit 37 detects that the coil current has reached the target maximum value IthP of the discharge current, it switches the transistor T12 out.

As described above, when the coil is energized 41a is started, the electrical energy that is in the output capacitor 34 has accumulated on the coil 41a discharged, and this accelerates the response time for opening the injector 41 .

After the drive control circuit 37 the transistor T12 has turned off, it performs constant current control and switches the transistor T11 on and off so that the following happens: The coil current, which is sensed from the voltage across the resistor R10 is applied, becomes a constant current, which is smaller than the nominal maximum value IthP.

A more detailed description follows. While the injection command signal S # n is high, the drive control circuit is conducting 37 performs the following control as constant current control: When it detects that the coil current has become equal to or less than a lower threshold value IthL, it switches the transistor T11 a; and when it detects that the coil current has become equal to or greater than an upper threshold value IthH, it switches the transistor T11 out. The relationship among the lower threshold value IthL, the upper threshold value IthH and the target maximum value IthP is as follows: IthL <IthH <IthP.

For this reason, when the coil current drops from the target maximum value IthP and becomes equal to or less than the lower threshold value IthL, the following takes place: The transistor T11 is turned on and off repeatedly, and the mean value of the coil current is controlled to a current between the upper threshold value IthH and the lower threshold value IthL.

The following processing is performed by this constant current control: After the transistor T12 has been turned off, a constant current flows from the power supply line Lp through the transistor T11 to the coil 41a , and the injector 41 is kept open by this constant storm. When the transistor turned on T11 is switched off, a current flows through the diode D12 to the coil 41a back. Like it in the second corner of the 2 shown becomes the transistor T11 kept on only for a moment after the injection command signal S # n goes high. This is due to the constant current control.

When the injection command signal S # n from the microcomputer 38 then goes from the high level to the low level, the drive control circuit switches 37 the transistor T10 out. It also stops the constant current control and also holds the transistor T11 switched off. As a result, the coil is energized 41a stopped to the injector 41 close, and the fuel injection of the injector 41 will be terminated. The other injectors 41 are also driven with the same procedure described above.

The description turns to 1 back. The ECU 31 also contains two resistors 57 and 58 that divide the battery voltage VB into an input voltage that the microcomputer 38 can use. A voltage (hereinafter referred to as partial voltage), which is a voltage applied at the connection point between the resistors 57 and 58 is applied and obtained by dividing the battery voltage VB is entered into the microcomputer 38 entered. The microcomputer 38 A / D converts the partial voltage from the resistors 57 and 58 by means of the A / D converter 54 and detects the battery voltage VB based on the resulting A / D converted value.

The ECU 31 also contains a thermistor 59 one end of which is connected to a ground line, and a pull-down resistor 60 , one end of which connects to the other end of the thermistor 59 is connected and at the other end of which the supply voltage Vcc is applied.

The thermistor 59 is a resistance element whose resistance value changes according to temperature and is in the vicinity of the output capacitor 34 (e.g. at a position adjacent to the output capacitor 34 ) in the ECU 31 assembled. Because of this, the resistance value of the thermistor changes 59 according to the internal temperature (also called ECU internal temperature) of the ECU 31 . The ECU internal temperature is also the ambient temperature of the output capacitor 34 .

A voltage (hereinafter also referred to as temperature monitoring voltage) applied to the connection point between the thermistor 59 and the resistance 60 changes according to the ECU internal temperature, and the temperature monitor voltage is input to the microcomputer 38 entered. The microcomputer 38 A / D converts the temperature monitor voltage by means of the A / D converter 54, and detects the ECU internal temperature from the resulting A / D converted value. The microcomputer 38 uses, for example, a data map or a calculation formula contained in the ROM 52 is stored in advance to convert the A / D converted value obtained from the temperature monitor voltage into the ECU internal temperature.

In the microcomputer 38 a starter signal STA is input which is brought to an active level (e.g. HIGH) when a starter cranks to start the internal combustion engine. The microcomputer 38 determines on the basis of this starter signal STA whether the starter is being operated or is in operation.

A more detailed description of the ECU follows 31 .

In this embodiment, the transistor T1 that is in series with the capacitor C1 is switched off when a drive signal from the microcomputer 38 is at a low level, and is turned on when the drive signal is at a high level. The microcomputer 38 brings the drive signal for the transistor T1 from the above power reset time (also the time at which the ECU 31 started) to a low level. The microcomputer 38 performs each of the first to fifth determination processes and the capacity recovery process described below, thereby switching the transistor T1 in and out. Each of these series of processing is carried out at certain time intervals, for example.

In the first determination process, the microcomputer determines 38 as it is in 3 it is shown whether the battery voltage VB is equal to or less than a predetermined voltage (in this example 6 V) ( S110 ). When it determines that the battery voltage VB is equal to or less than the predetermined voltage (S110: YES), it turns on the transistor T1 off (S120). In particular, it brings the drive signal for the transistor T1 to the low level. The predetermined voltage is set to a value of the battery voltage VB to which the voltage can drop when, for example, the starter is activated.

In the second determination process, the microcomputer determines 38 as it is in 4th it is shown whether the starter is operated (S130). When it determines that the starter is being operated (S130: YES), it turns on the transistor T1 off (S140).

In the third determination process, the microcomputer determines 38 as it is in 5 it is shown whether the engine speed NE is equal to or less than a predetermined speed (in this example 800 revolutions per minute) ( S150 ). When it determines that the engine speed NE is equal to or less than the predetermined speed (S150: YES), it turns on the transistor T1 off (S160). The predetermined speed is set to an idle speed or a value slightly larger than the idle speed.

In the fourth determination process, the microcomputer determines 38 as it is in 6th it is shown whether the number of continuous injections is equal to or less than a predetermined number (in this example two) ( S170 ). When it determines that the number of continuous injections is equal to or less than the predetermined number (S170: YES), it turns on the transistor T1 off (S180). The number of continuous injections means a number of fuel injections by means of which the injector 41 is caused to perform fuel injection in one fuel injection period. An example of a possible fuel injection period is a period from when the compression stroke is started to when the combustion stroke is ended. The fuel injection period may include part of the intake stroke or may be a period of the combustion stroke only.

In the fifth determination process, the microcomputer determines 38 as it is in 7th it is shown whether the ECU internal temperature is equal to or lower than a predetermined temperature (in this example, 0 ° C.) (S190). When it determines that the ECU internal temperature is equal to or lower than the predetermined temperature (S190: YES), it turns on the transistor T1 off (S200).

In the capacity recovery process, the microcomputer determines 38 as it is in 8th is shown in the first step S210 whether the transistor T1 is turned off. When the transistor T1 is not turned off (that is, if he is on), the microcomputer terminates 38 the capacity recovery process.

When the microcomputer 38 in S210 determines that the transistor T1 is switched off, he determines in the next step S220 whether the battery voltage VB is equal to or greater than a recovery voltage (8 V in this example) that is greater than the predetermined voltage shown in FIG S110 of the first determination process was determined. When the microcomputer 38 determines that the battery voltage VB is not equal to or greater than the recovery voltage (S220: NO), it ends the capacity recovery process. If it determines that the battery voltage VB is equal to or greater than the recovery voltage (S220: YES), it proceeds S230 .

In S230 determines the microcomputer 38 whether the starter is not operating (not operating). When the microcomputer 38 determines that the starter is being operated (S230: NO), it ends the capacity recovery process. When it determines that the starter is not being operated (S230: YES), it proceeds S240 .

In S240 determines the microcomputer 38 whether the engine speed NE is equal to or greater than a recovery speed (1000 revolutions per minute in this example). The recovery speed is greater than the predetermined speed used in the determination in S150 of the third determination process is used. When the microcomputer 38 determines that the engine speed NE is not equal to or greater than the recovery speed (S240: NO), it ends the capacity recovery process. When it determines that the engine speed NE is equal to or greater than the recovery speed (S240: YES), it proceeds S250 .

In S250 determines the microcomputer 38 whether the number of continuous injections is equal to or greater than a recovery number (three in this example). The number of times to be restored is greater than the predetermined number set in S170 of the fourth determination process is used. When the microcomputer 38 determines that the number of continuous injections is not equal to or greater than the recovery number (S250: NO), it ends the capacity recovery process. If it determines that the number of continuous injections is equal to or greater than the recovery number (S250: YES), it proceeds S260 .

In S260 determines the microcomputer 38 whether the ECU internal temperature is equal to or higher than a recovery temperature (20 ° C in this example). This recovery temperature is higher than the predetermined temperature used in S190 of the fifth determination process. When the microcomputer 38 determines that the ECU internal temperature is not equal to or higher than the recovery temperature (S260: NO), it ends the capacity recovery process. If it determines that the ECU internal temperature is equal to or higher than the recovery temperature (S260: YES), it proceeds S270 .

In S270 switches the microcomputer 38 the transistor T1 a. In particular, it brings the drive signal for the transistor T1 to a high level. As a result, the electrostatic capacity of the output capacitor becomes 34 from "Cap0" to "Cap0 + Cap1" restored. After that, the microcomputer ends 38 the capacity recovery process.

That is, the microcomputer 38 holds the transistor T1 from the moment the ECU 31 is started, switched off and thereby causes the electrostatic capacitance of the output capacitor 34 becomes smaller than the maximum value (Cap0 + Cap1). If all the conditions for the provisions in the steps S220 to S260 of the capacity restoration process apply, the microcomputer switches 38 the transistor T1 one to the electrostatic capacity of the output capacitor 34 to bring it back to the maximum value. If any of the terms of the provisions in the steps S110 , S130 , S150 , S170 and S190 of the first through fifth determination processes, the microcomputer switches 38 the transistor T1 out. It thereby causes the electrostatic capacity of the output capacitor 34 becomes smaller than the maximum value. If all the conditions for the provisions in the steps S220 to S260 of the capacity restoration process apply, the microcomputer switches 38 the transistor T1 again and thereby sets the electrostatic capacitance of the output capacitor 34 to the maximum value. The determination in S220 is equivalent to the recovery condition that is used when the transistor T1 is turned off in the first determination process, the determination in S230 is equivalent to the recovery condition used when the transistor T1 is turned off in the second determination process; the determination in S240 is equivalent to the recovery condition used when the transistor T1 is turned off in the third determination process; the determination in S250 is equivalent to the recovery condition used when the transistor T1 is turned off in the fourth determination process; and the determination in S260 is equivalent to the recovery condition used when the transistor T1 is turned off in the fifth determination process.

In the ECU 31 according to this embodiment, the boosting power supply device consists of the voltage converter 33 and the microcomputer 38 .

It is assumed that the following situation in the ECU 31 exists when fuel injection starts (that is, when energization of the coil 41a of the injector 41 is started): A charging of the output capacitor 34 a target voltage was reached too late and the capacitor voltage VC has not reached the target voltage. In this case, as indicated by the dotted line of the curve in the upper part of the 9 is shown, the following takes place: The time it takes for the coil current to reach the above-mentioned target maximum value IthP after the coil is energized 41a reached, becomes longer. This delays, as indicated by the dotted line in the lower part of the 9 the opening of the injector is shown 41 and the fuel injection control accuracy deteriorates (particularly, the injection amount decreases).

In the ECU 31 however, is the microcomputer 38 able to control the electrostatic capacity of the output capacitor 34 by turning off the transistor T1 to reduce. This reduction in the electrostatic capacity makes it possible to shorten the charging time (hereinafter also referred to as required charging time) that is required for the capacitor voltage VC to become equal to the target voltage. Therefore, the following situation can be prevented: Charging of the output capacitor 34 the target voltage is too late and the injector opens 41 delayed. (This situation is also referred to in the following as "Injector opening delay due to loading too late".)

The required charging time becomes longer with a decrease in the battery voltage VB, for example.

To handle this, the microcomputer switches 38 in the ECU 31 the transistor T1 off when the battery voltage VB is equal to or less than the predetermined voltage (S110: YES → S120). Therefore, an increase in the required charging time can be achieved due to a decrease in the battery voltage VB by decreasing the electrostatic capacity of the output capacitor 34 be prevented. As a result, injector opening delay due to late charging can be prevented.

At the engine starting timing when the starter is activated, the battery voltage VB is lower than that during engine operation.

To handle this, the microcomputer switches 38 the transistor T1 off when the starter is operated (S 130: YES → S140). Therefore, an increase in the required charging time due to a decrease in the battery voltage VB by the starter operation by reducing the electrostatic capacity of the output capacitor 34 be prevented. As a result, injector opening delay due to late charging can be prevented.

When the engine speed NE is low, no multi-stage injection is performed, even during engine operation. Therefore, the electrostatic capacity of the output capacitor is allowed 34 be lower than the maximum value "Cap0 + Cap1".

When the engine speed NE is equal to or less than the predetermined speed, the microcomputer switches 38 because of this the transistor T1 off (S150: YES → S160). As a result, even if, for example, the battery voltage VB drops at the time of low engine speed when the engine speed NE is equal to or less than the predetermined speed, the following can be performed: The required charging time can be prevented from being prolonged. As a result, injector opening delay due to late charging can be prevented.

When multi-stage injection is not performed, or when multi-stage injection is performed but the number of continuous injections is low, the electrostatic capacity of the output capacitor is allowed 34 be smaller than the maximum value "CapO + Cap1".

When the number of continuous injections is equal to or less than the predetermined number, the microcomputer switches 38 because of this the transistor T1 off (S170: YES → S180). Therefore, the following can be prevented when the number of continuous injections is equal to or less than the predetermined number and the electrostatic capacity of the output capacitor 34 may be less than "Cap0 + Cap1": An extension of the required charging time can be prevented, for example even if the battery voltage VB drops. As a result, injector opening delay due to late charging can be prevented.

The ESR (equivalent series resistance) of the output capacitor 34 increases with a Reduction of the ambient temperature, and this increases the required charging time.

To handle this, the microcomputer performs 38 performs the following processing: It detects the ECU internal temperature as the ambient temperature of the output capacitor 34 ; and when it determines that the detected ECU internal temperature is equal to or less than the predetermined temperature, it turns on the transistor T1 off (that is, if it determines that the ambient temperature of the output capacitor 34 is equal to or less than the predetermined temperature, it switches the transistor T1 off) (S190: YES → S200). Therefore, an increase in the required charging time may be due to a decrease in the ambient temperature of the output capacitor 34 by reducing the electrostatic capacitance of the output capacitor 34 be prevented. As a result, injector opening delay due to late charging can be prevented.

The ambient temperature of the output capacitor 34 can also be detected, for example, by having a temperature sensor on the outer wall surface of one of the capacitors C0 and C1 of the output capacitor 34 is arranged. The microcomputer 38 detects the ECU internal temperature as the ambient temperature of the output capacitor 34 ; therefore, it can easily detect the ambient temperature of the output capacitor.

When the ECU 31 in the engine compartment 61 (please refer 1 ) is arranged in which the internal combustion engine is housed in a vehicle, the microcomputer 38 perform the following processing: It can measure the temperature of the engine compartment 61 than the ambient temperature of the output capacitor 34 capture. This is possible because there is a correlation between the temperature of the engine compartment 61 and the ECU internal temperature (and thus to the ambient temperature of the output capacitor 34 ). With a temperature sensor for detecting the temperature of the engine compartment 61 can the microcomputer 38 for example the temperature of the engine compartment 61 based on the output of the temperature sensor.

The microcomputer 38 can be the temperature of a specific object, the temperature of which has a correlation to the temperature of the engine compartment 61 has, as the temperature of the engine compartment 61 (and thus the ambient temperature of the output capacitor 34 ) capture. Examples of the specific object are fuel that is supplied to the internal combustion engine, engine oil for the internal combustion engine, cooling water for the internal combustion engine, and the like. Among these objects, the temperature of the fuel probably has the highest correlation with the temperature of the engine compartment 61 on. The temperatures of the fuel, the engine oil and the cooling water are usually each measured with a fuel temperature sensor 63 , an oil temperature sensor 64 and a coolant temperature sensor 67 (please refer 1 ) recorded in the vehicle for other purposes. Therefore you can do this without an additional sensor by inputting the respective signals from these sensors 63 to 67 into the microcomputer 38 are recorded.

Whatever temperature than the ambient temperature of the output capacitor 34 is detected, the determination of high and low in S190 the 7th only needs to be performed in relation to the recorded temperature. This also applies to the step S260 in 8th .

Second embodiment

The following is a description of an ECU according to a second embodiment. The same reference number “31” is used for the ECU as in the first embodiment. In addition, the same reference numerals are used for the same components and processing steps as in the first embodiment. The same applies to the further described embodiments.

The ECU 31 according to the second embodiment differs from that of the first embodiment in that the microcomputer 38 the capacity recovery process according to 10 instead of the process according to the 3 to 8th performs. The capacity recovery process according to 10 is carried out, for example, at predetermined time intervals.

In the capacity recovery process, the microcomputer determines 38 In the first step S310 as it is in 10 it is shown whether the starter is not being operated. When the microcomputer 38 determines that the starter is being operated (S310: NO), it ends the capacity recovery process. If it determines that the starter is not operated (that is, not operated) (S310: YES), it proceeds to S320 .

In S320 determines the microcomputer 38 whether the battery voltage VB is equal to or greater than a predetermined normal determination value (8 V in this example). When the microcomputer 38 determines that the battery voltage VB is not equal to or greater than the normal determination value (S320: NO), it ends the capacity recovery process. When it determines that the battery voltage is equal to or greater than the VB normal determination value (S320: YES), it proceeds S330 .

In S330 determines the microcomputer 38 whether the engine speed NE is equal to or greater than an operation determination value (1000 revolutions per minute in this example) that is equal to or greater than the idling speed. When the microcomputer 38 determines that the engine speed NE is not equal to or greater than the operation determination value (S330: NO), it ends the capacity recovery process. When it determines that the engine speed NE is equal to or greater than the operation determination value (S330: YES), it proceeds to S340 .

In S340 switches the microcomputer 38 the transistor T1 and then ends the capacity recovery process.

A more detailed description follows. When the ECU 31 the battery voltage VB is supplied and the ECU 31 has started the microcomputer 38 the transistor T1 already switched off as described above. If the result of the determination in all steps S310 to S330 If YES, it determines that the engine start is complete and causes the transistor to be off T1 is switched on. At this point, the electrostatic capacity of the output capacitor changes 34 from "Cap0" to the normal value "Cap0 + Cap1".

With the ECU constructed as described above 31 it is possible to cause the electrostatic capacitance of the output capacitor 34 during a period from when the ECU 31 is started until the point in time at which the start of the internal combustion engine is completed, becomes equal to “Cap0”, which is smaller than the normal value “Cap0 + Cap1”.

For this reason, even if the battery voltage VB drops due to an operation of the starter when the internal combustion engine is started, the following can be performed: Because the electrostatic capacity of the output capacitor 34 is reduced until the start of the internal combustion engine is completed, an extension of the required charging time can be prevented. As a result, injector opening delay due to late charging can be prevented. Therefore, when the internal combustion engine is started, the injection amount is not decreased, and favorable starting property of the internal combustion engine can be ensured.

The microcomputer 38 determines whether the following conditions apply: the starter should not be operated (S310: YES); and the battery voltage VB should be equal to or greater than the normal determination value (S320: YES); and the engine speed should be equal to or greater than the operation determination value (S330: YES). Therefore, he can correctly determine that the start of the internal combustion engine has been completed.

Third embodiment

The ECU 31 according to the third embodiment differs from that of the second embodiment in that, after the microcomputer 38 the transistor T1 in the capacity recovery process of the 10 has switched on the processing in 10 does not perform. He leads the respective processes of the 3 to 8th for example at certain time intervals as in the first embodiment.

In this ECU 31 becomes the transistor T1 like in the ECU 31 according to the first embodiment, even after the engine start has been completed and the transistor turned on T1 switched off, switched on and off. Therefore, it has the same effects as with the ECU 31 achieved according to the first embodiment.

Modification 1

The microcomputer 38 may be configured not to perform the fourth process according to the first embodiment and the third embodiment. In this case you can use the steps S220 to S260 of the capacity recovery process of the 8th a step corresponding to the determination processing that is not performed can be omitted.

Modification 2

If the result of the determination in one or two of the steps S310 to S330 the 10 According to the second embodiment and the third embodiment, if YES, the microcomputer 38 determine that the start of the internal combustion engine has been completed, and the transistor T1 turn on.

If the result of the determination in all steps S310 to S330 If YES and it is determined that some other condition holds, the microcomputer may 38 determine that the start of the internal combustion engine has been completed, and the transistor T1 turn on. An example of a possible further condition is that the vehicle speed is equal to or greater than a predetermined value.

Modification 3

In each embodiment and modification described above, the output capacitor 34 have three or more capacitors. In this case too, the following measures can be taken: A transistor (the same as T1 in 1 ) can be used as a capacitance adjustment switch in series with any capacitor other than the one capacitor C0 to be ordered; and each of these transistors is turned on and off according to the circumstances.

So far, embodiments of the present invention have been described. However, the invention is not limited to the above-described embodiments and various modifications can be made. The above numerical values are only examples.

The functions of a component in the embodiments described above can, for example, be divided into several components or the functions of several components can be integrated into one component. At least a part of the configuration of any of the above-described embodiments can be replaced with a known configuration having similar functions. Part of the configuration of any of the above-described embodiments can be omitted as long as the problem can be solved. At least a part of the configuration of one of the above-described embodiments may be added to or replaced with a configuration of another of the above-described embodiments.

All modes included in the technical idea described above represent embodiments of the present invention. The injector 41 does not have to have a solenoid, for example, but may be an injector which has a piezo element as a valve opening electric load and in which the valve is opened by loading and expanding the piezo element. Apart from the amplification power supply device described above, the present invention can be carried out according to various modes including: a system including the amplification power supply device as a component; a program that causes a computer to serve as a boosting power supply device; a medium on which the program is recorded; a reinforcement process; and similar.

Note that a flowchart or the processing of the flowchart in the present application includes sections (also referred to as steps), each as, for example, S110 be represented. In addition, each section can be divided into multiple subsections, while multiple sections can be combined into a single section. In addition, each section configured in this way can also be referred to as a device, module or device.

While the present invention has been described with reference to the embodiments thereof, it should be understood that the invention is not limited to these embodiments and constructions. The present invention covers various modifications and equivalent arrangements. While various combinations and configurations have been described, other combinations and configurations including more, less, or a single element are also conceivable within the scope of the present invention.

Claims (12)

Boost power supply device, which is arranged in a control device (31) that drives an injector (41) for injecting fuel into an internal combustion engine of a vehicle, the injector (41) being designed to prevent mechanical vibration caused by the internal combustion engine being transmitted to the injector (41), affects an operation of a valve body, the booster power supply device comprising: an output capacitor (34) that accumulates electric power that is discharged to an injector opening electric load (41a) for opening the injector (41); a charging circuit (35) that boosts a battery voltage (VB) of the vehicle and charges the output capacitor (34); and a charging control circuit (36) which controls the charging circuit (35) in such a way that a charging voltage for the output capacitor (34) becomes equal to a target voltage, the output capacitor (34) containing a plurality of capacitors (C0, C1) connected in parallel, the boosting power supply device further comprises: a capacitance setting switch (T1) connected in series with a capacitor (C1) other than a particular one of the capacitors (C0, C1); and a switching device (38, S110 to S270, S310 to S340) which controls switching on and off of the capacitance setting switch (T1), wherein the capacitance setting switch (T1) connects the one capacitor (C1) connected in series with the capacitance setting switch (T1) is, switches in parallel with the special capacitor (C0) when the capacitance setting switch (T1) is turned on, and the capacitance adjusting switch (T1) breaking the connection of the one capacitor (C1) connected in series with the capacitance adjusting switch (T1) and reducing an electrostatic capacitance of the output capacitor (34) when the capacitance adjusting switch (T1) is turned off. Boost power supply device according to Claim 1 wherein the switching device (38, S110, S120) turns off the capacity setting switch (T1) when the battery voltage (VB) is equal to or less than a predetermined voltage. Boost power supply device according to Claim 1 or 2 wherein the switching device (38, S130, S140) turns off the capacity setting switch (T1) when a starter which cranks to start the internal combustion engine is in operation. Boost power supply device according to one of Claims 1 to 3 wherein the switching device (38, S150, S160) turns off the capacity setting switch (T1) when a speed of the internal combustion engine is equal to or less than a predetermined speed. Boost power supply device according to one of Claims 1 to 4th wherein the injector (41) injects the fuel into a cylinder of the internal combustion engine, and wherein the switching device (38, S170, S180) turns off the capacity setting switch (T1) when a number of fuel injections of the injector (41) during a fuel injection period of the cylinder equal or less than a predetermined number of fuel injections. Boost power supply device according to one of the Claims 1 to 5 wherein the switching device (38, S190, S200) turns off the capacitance setting switch (T1) when an ambient temperature around the output capacitor (34) is equal to or lower than a predetermined temperature. Boost power supply device according to Claim 6 wherein the switching device (38, S190, S200) detects an internal temperature of the control device (31) as an ambient temperature around the output capacitor (34). Boost power supply device according to Claim 6 , wherein the control device (31) is arranged in an internal combustion engine room (61) in which the internal combustion engine is mounted in the vehicle, and wherein the switching device (38, S190, S200) a temperature of the internal combustion engine room (61) as an ambient temperature around the output capacitor ( 34) recorded. Boost power supply device according to Claim 8 wherein the switching device (38, S190, S200) detects a temperature of an object, which has a correlation with the temperature of the internal combustion engine room (61), as the temperature of the internal combustion engine room (61). Boost power supply device according to Claim 9 , where the object is the fuel that is supplied to the internal combustion engine. Boost power supply device according to Claim 1 wherein the control device (31) and the booster power supply device are operated when the control device (31) is supplied with the battery voltage (VB) serving as a power source, the switching device (38, S310 to S340) turning off the capacity setting switch (T1), when the control device (31) is supplied with the battery voltage (VB) and the control device (31) starts its operation, and the control device (31) turns on the capacity setting switch (T1) when starting of the internal combustion engine is completed after the switching device (38 , S310 to S340) has switched off the capacity setting switch (T1). Boost power supply device according to Claim 11 , wherein the switching device (38, S310 to S340) determines that the starting of the internal combustion engine is completed when the control device (31) determines that a starter for cranking for starting the internal combustion engine is not in operation, the battery voltage (VB) is equal to or is greater than a predetermined normal determination value and the rotational speed of the internal combustion engine is equal to or greater than an operation determination value that is equal to or greater than an idling speed.

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