JP2016205224A - Increasing pressure control device for fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an increasing pressure control device for a fuel injection valve capable of improving a starting characteristic of an internal combustion engine while assuring a reduction in consumption power at the time of stopping of the internal combustion engine.SOLUTION: This invention relates to an increasing pressure control device for a fuel injection valve for controlling an increasing value of voltage applied to a fuel injection valve 4 arranged at an internal combustion engine 3. This control device includes: a voltage increasing circuit 20 for increasing a battery voltage VB; applying means 2 for applying an increased voltage VC increased by the voltage increasing circuit 20 to the fuel injection valve 4 in order to open the fuel injection valve 4; waiting voltage setting means 2 for setting a waiting voltage VR to be held at least as the increased voltage VC; and control means 2 for stopping a voltage increasing operation performed by the increasing circuit 20 when the internal combustion engine 3 is stopped, and restarting the voltage increasing operation performed by the increasing circuit 20. Waiting voltage setting means sets the waiting voltage VR to be increased more as the battery voltage VB keeps its lower value.SELECTED DRAWING: Figure 3

Description

  The present invention is applied to a hybrid vehicle, a vehicle in which idle stop is executed, and the like, and a booster for a fuel injection valve that controls boosting of a voltage applied to an electromagnetic fuel injector provided in the internal combustion engine. The present invention relates to a control device.

  2. Description of the Related Art Conventionally, for example, a device disclosed in Patent Document 1 is known as an application of a boost control device for a fuel injection valve to an engine control device for a vehicle in which idle stop is executed. This engine control device is provided with a booster circuit for boosting the power supply voltage supplied from the onboard battery, and by applying the boosted high voltage to the fuel injector, the response of the fuel injector is improved. The valve is opened quickly. Further, in this engine control device, while the engine is stopped due to idling stop when the vehicle is stopped, the boosting operation of the booster circuit is stopped, and when the engine start operation is started, the boosting operation is restarted and the fuel injection control is started. In the meantime, the boosted voltage is controlled to be boosted to a predetermined target high voltage.

  In the engine control device, when the boosting operation by the boosting circuit is stopped, the voltage stored in the high-voltage capacitor of the boosting circuit, that is, the voltage output to be applied to the fuel injection valve (hereinafter referred to as “output voltage”). ) Gradually decreases due to natural discharge to a resistor or the like included in the booster circuit. Note that the output voltage that decreases in this way is maintained at a voltage substantially equal to the power supply voltage of the vehicle-mounted battery.

JP 2010-265811 A

  In the above-described engine control device, the boosting operation by the boosting circuit is stopped while the engine is stopped due to idle stop, so that the power consumption of the vehicle-mounted battery can be reduced accordingly. However, as described above, the output voltage of the booster circuit gradually decreases with the stop of the boost operation, so that when the duration of the idle stop is long, the stop time of the boost operation becomes long, and as a result, the output of the boost circuit The voltage drops to the same level as the power supply voltage of the in-vehicle battery. For this reason, when restarting the engine, it takes time to boost the reduced output voltage to the target high voltage, and it also takes time to restart the engine. In addition, when the power supply voltage of the in-vehicle battery is reduced, the output voltage of the booster circuit is further decreased, thereby taking more time to restart the engine and taking more power from the in-vehicle battery, As a result, the engine may not be restarted properly. The above problems are remarkable in the case of a hybrid vehicle having an engine and a motor as power sources, particularly a hybrid vehicle that travels for a relatively long time by driving only the motor with the engine stopped.

  The present invention has been made to solve the above-described problems, and is for a fuel injection valve capable of improving startability of an internal combustion engine while ensuring reduction of power consumption when the internal combustion engine is stopped. An object of the present invention is to provide a step-up control device.

  In order to achieve the above object, the invention according to claim 1 is a boost control device for a fuel injection valve that controls boosting of a voltage applied to an electromagnetic fuel injection valve 4 provided in an internal combustion engine 3. The booster circuit 20 boosts the voltage VB of the power source (battery 11 in the embodiment (hereinafter the same in this section)) and the booster circuit 20 boosts the voltage to open the fuel injection valve 4. Applying means (ECU2) for applying the boosted voltage (capacitor voltage VC) to the fuel injection valve 4, standby voltage setting means (ECU2) for setting a predetermined standby voltage VR to be held at least as the boosted voltage VC, and the internal combustion engine 3 Is stopped (step 1: NO), the boosting operation by the booster circuit 20 is stopped (step 8), and the boosted voltage VC that gradually decreases accordingly is equal to or lower than the set standby voltage VR. (Step 7: YES), the control means (ECU2, step 9) for restarting the boosting operation by the booster circuit 20 is provided, and the standby voltage setting means reduces the standby voltage VR as the power supply voltage VB is lower. It is characterized by being set to be high.

  According to this configuration, the voltage of the power supply is boosted by the booster circuit, and the boosted voltage is applied to the fuel injector, whereby the fuel injector can be opened quickly with high responsiveness. Further, when the internal combustion engine stops, the boosting operation by the boosting circuit is stopped by the control means. Specifically, for example, in a hybrid vehicle having an internal combustion engine and a motor as a power source, the vehicle travels by driving only the motor and the internal combustion engine stops, or has only the internal combustion engine as a power source and performs an idle stop. In the vehicle to be operated, when the internal combustion engine stops due to execution of idle stop, the boosting operation by the booster circuit is stopped. Thereby, the power consumption of the power supply voltage can be reduced by the amount of power used in the booster circuit for performing the boosting operation.

  Further, in this case, with the stop of the boosting operation, the boosted voltage boosted by the booster circuit gradually decreases due to natural discharge to a resistor or the like included in the booster circuit. When the boosted voltage becomes equal to or lower than a predetermined standby voltage, the boosting operation by the booster circuit is resumed by the control means. The standby voltage is a voltage that should be held at least as a boosted voltage. By appropriately setting the standby voltage, the boosted voltage of the booster circuit is excessively lowered or the boosting takes time. It is possible to prevent the excess.

  Further, the standby voltage is set to be higher as the power supply voltage is lower. Therefore, for example, even when the power supply voltage decreases as the electrical load in the vehicle increases, the standby voltage is set higher than in the prior art, so that the boosted voltage can be held at a relatively high voltage. Thereby, when the boosting operation by the booster circuit is resumed, the boosted voltage can be quickly boosted to a desired high voltage, and the startability of the internal combustion engine can be improved.

  According to a second aspect of the present invention, in the boost control device for a fuel injection valve according to the first aspect, a startability parameter (engine water temperature TW, HV vehicle altitude AL) indicating the degree of startability of the internal combustion engine 3 is detected. Startability parameter detecting means (water temperature sensor 61, atmospheric pressure sensor 62, outside air temperature sensor 63 and ECU 2) for performing the control, and the control means is configured such that the detected startability parameter has a predetermined threshold value (predetermined temperature TWREF, When the predetermined altitude (ALREF) is a value representing deterioration of startability (step 4: NO, step 5: YES), the predetermined normal boost control by the booster circuit 20 is executed (step 2). Features.

  According to this configuration, when the startability parameter representing the degree of startability of the internal combustion engine is detected and the value is a value on the side representing deterioration of the startability with respect to the predetermined threshold value, the booster circuit Predetermined normal boosting control is executed. For example, the engine water temperature or the vehicle altitude can be used as the startability parameter, and when the engine water temperature is lower than the temperature as the predetermined threshold, or the vehicle altitude is When the internal combustion engine is in a deteriorated startability state, such as when it is higher than the altitude, normal boost control by the booster circuit is executed in advance even when the internal combustion engine is stopped. Thereby, the high voltage which should be applied to a fuel injection valve is ensured previously, and the startability of an internal combustion engine can be improved.

1 is a diagram schematically showing a boost control device for a fuel injection valve according to an embodiment of the present invention, together with an internal combustion engine to which the boost control device is applied. It is a circuit diagram which shows the drive circuit for driving a fuel injection valve. It is a flowchart which shows a pressure | voltage rise control process. It is a table for setting a standby voltage.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a boost control device for a fuel injection valve applied to a hybrid vehicle (not shown) (hereinafter referred to as “HV vehicle”) having an internal combustion engine (hereinafter referred to as “engine”) 3 and a motor 5 as power sources. . An engine 3 shown in the figure is, for example, a gasoline engine having four cylinders (not shown). Each cylinder is provided with a fuel injection valve (hereinafter referred to as “injector”) 4, and combustion is performed from the injector 4. Fuel is directly injected into the chamber (not shown). The operation of the injector 4 is controlled by an ECU 2 described later.

  The injector 4 is of an electromagnetic type, and although not shown, an electromagnet fixed to the upper end in the casing, an armature disposed below the electromagnet, and disposed between these electromagnets and the armature. It comprises a spring and a valve body provided integrally below the armature. The electromagnet has a yoke and a coil 4a wound around the yoke, and a drive circuit 10 shown in FIG. 2 is connected to the coil 4a. Further, the spring is provided so as to bias the valve body toward the valve closing side.

  FIG. 2 shows the drive circuit 10 included in the ECU 2. As shown in the figure, the drive circuit 10 drives the injector 4 by applying a voltage to the booster circuit 20 for boosting the voltage of the battery 11 (power source) mounted on the HV vehicle and the coil 4a of the injector 4. It is comprised by the injector drive circuit 30 for doing. The operations of these circuits 20 and 30 are controlled by a CPU 40 described later. The battery 11 is charged using a generator (not shown) that uses the engine 3 as a power source.

  The booster circuit 20 includes a first switch 21, a second switch 22, a coil 23, a diode 24, and a capacitor 25. The first switch 21 is composed of an N-channel FET, and its drain is connected to the output side of the coil 23 connected to the battery 11. The source and gate of the first switch 21 are connected to the ground and the CPU 40, respectively. When the first drive signal SD1 is input to the gate from the CPU 40, the first switch 21 is turned on and the drain-source is energized.

  The second switch 22 is also composed of an N-channel type FET, and its drain is connected between the first switch 21 and the coil 23. The source and gate of the second switch 22 are connected to the capacitor 25 and the CPU 40, respectively. When the second drive signal SD2 is input to the gate from the CPU 40, the second switch 22 is turned on and the drain-source is energized.

  The diode 24 is provided in parallel with the second switch 22, the anode side thereof being connected to the drain of the second switch 22, and the cathode side being connected to the source of the second switch 22.

  In the booster circuit 20, a boosting operation is performed as follows. First, the first drive signal SD1 is output, and the first switch 21 is turned on. As a result, when the voltage VB of the battery 11 (hereinafter referred to as “battery voltage”) VB is applied to the coil 23, the coil current IL flows through the coil 23 and electric energy is stored.

  From this state, the output of the first drive signal SD1 is stopped, the first switch 21 is turned OFF, and immediately after that, the second drive signal SD2 is output and the second switch 22 is turned ON. As a result, the electrical energy stored in the coil 23 is supplied to the capacitor 25 via the second switch 22 and stored. As a result, the coil current IL decreases and the voltage of the capacitor 25 (hereinafter referred to as “capacitor voltage”) VC increases.

  Thereafter, the output of the second drive signal SD2 is stopped, the second switch 22 is turned OFF, and immediately thereafter, the first drive signal SD1 is output and the first switch 21 is turned ON, whereby the coil 23 is electrically connected. Energy is stored again. Thereafter, similarly, the boosting operation is performed by alternately switching the ON operation of one of the first and second switches 21 and 22 and the OFF operation of the other of the first and second switches 21 and 22 in synchronization with each other.

  The injector drive circuit 30 includes third to fifth switches 31 to 33 each formed of an N-channel FET, a Zener diode 34, and the like.

  The drain, source, and gate of the third switch 31 are connected to the booster circuit 20, one end of the coil 4a of the injector 4, and the CPU 40, respectively. When the third drive signal SD3 is input from the CPU 40 to this gate, the third switch 31 is turned on and the drain-source is energized.

  The drain, source, and gate of the fourth switch 32 are connected to the battery 11, one end of the coil 4a of the injector 4, and the CPU 40, respectively. When the fourth drive signal SD4 is input from the CPU 40 to this gate, the fourth switch 32 is turned on, and the drain-source is energized.

  The drain, source, and gate of the fifth switch 33 are connected to the other end of the coil 4a of the injector 4, the ground, and the CPU 40, respectively. When the fifth drive signal SD5 is input from the CPU 40 to this gate, the fifth switch 33 is turned on and the drain-source is energized.

  The Zener diode 34 has an anode side connected to the ground and a cathode side connected to the other end of the coil 4 a of the injector 4.

  With the above configuration, in this injector drive circuit 30, the third to fifth switches 31 to 33 are switched on / off in accordance with the third to fifth drive signals SD3 to SD5 from the CPU 40, and the coil 4a of the injector 4 is switched. The operation of the injector 4 is controlled by controlling the voltage application state.

  Specifically, when the third to fifth switches 31 to 33 are in the OFF state, the coil 4a of the injector 4 is not applied, and the drive current IAC does not flow through the coil 4a. By being located at the valve closing position by the urging force of the spring, the valve is kept closed.

  When the third and fifth switches 31 and 33 are turned on from this state, a boosted capacitor voltage VC (for example, 40 V) is applied to the coil 4a of the injector 4, whereby a large drive current IAC flows through the coil 4a. The electromagnet of the injector 4 is overexcited (overexcitation control). By this overexcitation, the valve body is pulled toward the open side against the biasing force of the spring, whereby the injector 4 is opened and fuel is injected from the injector 4.

  After that, when the third switch 31 is turned off to finish the application of the capacitor voltage VC and the fourth switch 32 is turned on, the battery voltage VB (for example, 12V) is applied to the coil 4a of the injector 4. As a result, when the small drive current IAC flows through the coil 4b, the injector 4 is held in the valve open state, and fuel injection is continued (holding control).

  When the fourth and fifth switches 32 and 33 are turned off from this state, the application of the battery voltage VB is completed, and accordingly, the valve body is returned to the valve closing position where the valve body is fully closed by the biasing force of the spring. The injector 4 is closed, and the fuel injection is completed. Further, the current remaining in the coil 4a of the injector 4 flows to the ground via the Zener diode 34, whereby the electromagnet of the injector 4 is brought into a non-excited state.

  As described above, when the injector 4 is opened, by first performing overexcitation control, by applying the boosted capacitor voltage VC to the coil 4a of the injector 4 and overexciting the electromagnet, Sufficient magnetic force is secured to quickly open the injector 4 against the high fuel pressure. Further, subsequently, holding control is executed, and the battery voltage VB is applied to the coil 4a, whereby the valve open state of the injector 4 is held.

  As shown in FIGS. 1 and 2, the drive circuit 10 and the booster circuit 20 are provided with voltmeters 51 and 52 (shown only in FIG. 1), respectively. The former voltmeter 51 detects the voltage VB of the battery 11 and outputs the detection signal to the CPU 40, while the latter voltmeter 52 detects the capacitor voltage VC and outputs the detection signal to the CPU 40.

  As shown in FIG. 1, the ECU 2 is electrically connected to a water temperature sensor 61, an atmospheric pressure sensor 62, an outside air temperature sensor 63 (startability parameter detecting means), and a crank angle sensor 64. The water temperature sensor 61 detects the engine water temperature TW, which is the temperature of the cooling water circulating in the cylinder block of the engine 3, and outputs a detection signal to the ECU 2. The atmospheric pressure sensor 62 detects the atmospheric pressure PA, the outside air temperature sensor 63 detects the outside air temperature TA, and outputs those detection signals to the ECU 2. The ECU 2 calculates the altitude AL at which the HV vehicle is running or stopped based on the detected atmospheric pressure PA and the outside temperature TA.

  Further, the crank angle sensor 64 outputs a CRK signal and a TDC signal, which are pulse signals, to the ECU 2 as the crankshaft (not shown) of the engine 3 rotates. The CRK signal is output every predetermined crank angle (for example, 1 degree). The ECU 2 calculates the rotational speed of the engine 3 based on the CRK signal. The TDC signal is a signal indicating that a piston (not shown) is in a predetermined crank angle position slightly before the top dead center at the start of the intake stroke in any cylinder. When the engine 3 is a 4-cylinder type as described above, it is output every 180 degrees of crank angle.

  The CPU 40 constitutes an ECU 2 including a microcomputer together with a RAM, a ROM, an I / O interface (all not shown), and the like. The ECU 2 controls the ON / OFF of the first and second switches 21 and 22 in accordance with a control program stored in the ROM, and controls the boosting operation of the booster circuit 20 and the third to fifth switches 31 to 31. By controlling ON / OFF of 33, the injector 4 is driven to execute fuel injection control for controlling the fuel injection amount and fuel injection timing. The ECU 2 corresponds to the application means, standby voltage setting means, control means, and startability degree detection means of the present invention.

  FIG. 3 is a flowchart showing the boost control process. This process is repeatedly executed at a predetermined cycle. In this process, first, in step 1 (illustrated as “S1”, the same applies hereinafter), it is determined whether or not the engine 3 is in operation. When the determination result is YES, normal boost control is executed (step 2), and this process is terminated. This normal boost control is a boost control performed to drive the injector 4 during operation of the engine 3 by executing the above-described overexcitation control and holding control.

  On the other hand, when the step 1 is NO and the engine 3 is stopped or stopped, it is determined whether or not the engine start flag F_ENGSTART is “1”. The engine start flag F_ENGSTART is a flag indicating that the stopped engine 3 is in a state to be started. Specifically, the engine start flag F_ENGSTART is a predetermined value that should start the engine 3 when the HV vehicle is traveling by driving only the motor 5 or when the idle stop is executed in the stopped HV vehicle. It is set to “1” when the condition is satisfied. The engine start flag F_ENGSTART is reset to “0” when the engine 3 is started.

  If the determination result in step 3 is NO and the engine 3 start condition is not satisfied, it is determined whether or not the engine water temperature TW (startability parameter) is equal to or higher than a predetermined temperature TWREF as a threshold value ( Step 4) When the determination result is YES, it is determined whether or not the altitude AL (startability parameter) of the HV vehicle is equal to or higher than a predetermined altitude ALREF as a threshold value (step 5).

  When the determination result of step 4 is NO and the engine water temperature TW is low, or when the determination result of step 5 is YES and the altitude AL of the HV vehicle is high, it is assumed that the engine 3 is in a state in which startability has deteriorated. In order to improve the startability of the engine 3, the normal boost control in step 2 is executed, and this process is terminated. Thereby, a high voltage to be applied to the injector 4 can be secured in advance, and the startability of the engine 3 can be improved.

  On the other hand, when the determination result of step 4 is YES and the determination result of step 5 is NO, the process proceeds to step 6, and the standby voltage VR is set by searching the standby voltage setting table of FIG. 4 according to the battery voltage VB. calculate. As shown in the figure, in this standby voltage setting table, the standby voltage VR is set higher as the battery voltage VB is lower.

  Next, it is determined whether or not the capacitor voltage VC of the booster circuit 20 is equal to or lower than the standby voltage VR calculated in step 6 above. If the determination result is NO and the capacitor voltage VC exceeds the standby voltage VR, the boosting operation is stopped and the present process is terminated in order to reduce the power consumption of the battery 11.

  When the determination result of step 3 is YES, that is, when the engine start flag F_ENGSTART is “1” and the start condition of the engine 3 is satisfied, or when the start condition is satisfied, the boost operation by the boost circuit 20 is executed. (Step 9). In this case, simultaneously with the start of the boosting operation, the time counting by the up-counting timer is started, and the boosting time TUP that is the elapsed time is measured.

  Next, in step 10, it is determined whether or not the capacitor voltage VC of the booster circuit 20 is equal to or higher than a drive voltage VINJ (for example, 40 V) for driving the injector 4. When the determination result is YES, it is not necessary to increase the capacitor voltage VC boosted by the boosting operation by the boosting circuit 20 any more. Therefore, the step 8 is executed, that is, the boosting operation is stopped, and this processing is performed. Exit. On the other hand, when the determination result in step 10 is NO, it is determined whether or not the boost time TUP is equal to or longer than the predetermined time TUPREF (step 11). The predetermined time TUPREF is set to be longer than the time required for the capacitor voltage VC to reach the drive voltage VINJ after the boost operation is started in the normal boost circuit 20.

  When the determination result in step 11 is NO, the boosting operation is being executed, and this process is terminated as it is. On the other hand, when the determination result in step 11 is YES, since the capacitor voltage VC has not reached the desired drive voltage VINJ even after a predetermined time TUPREF has elapsed since the start of the boost operation, the boost circuit 20 fails. If so, the failure process is executed (step 12). In this step-up circuit failure process, for example, when a step-up operation by the step-up circuit 20 is being executed, the step-up operation is stopped and a predetermined fail-safe operation is executed.

  As described above in detail, according to the present embodiment, during the operation of the engine 3, the normal boost control by the boost circuit 20 is performed, while the boost operation by the boost circuit 20 is stopped when the engine 3 is stopped. . Thereby, the power consumption of the battery voltage VB can be reduced by the amount of power used in the booster circuit 20 to perform the boost operation. As the boosting operation is stopped, the capacitor voltage VC of the booster circuit 20 gradually decreases due to natural discharge to a resistor included in the booster circuit 20, but the capacitor voltage VC becomes equal to or lower than a predetermined standby voltage VR. The boosting operation by the booster circuit 20 is resumed. As a result, the capacitor voltage VC is maintained at the standby voltage VR or higher, so that it is possible to prevent the capacitor voltage VC from being excessively lowered or resulting from taking too much time for boosting.

  Further, since the standby voltage VR is set to be higher as the battery voltage VB is lower, for example, even when the battery voltage VB is reduced as the electrical load in the HV vehicle increases, Since VR is set high, the capacitor voltage VC can be maintained at a relatively high voltage. Thus, when the boosting operation by the booster circuit 20 is resumed, the boosted voltage can be quickly boosted to a desired high voltage, and the startability of the engine 3 can be improved.

  In addition, this invention can be implemented in various aspects, without being limited to the said embodiment described. For example, in the embodiment, the case where the present invention is applied to a hybrid vehicle has been described. However, the present invention can also be applied to a vehicle having only an engine as a power source and executing an idle stop.

  In the embodiment, the engine water temperature TW and the altitude of the HV vehicle are employed as the startability parameters of the present invention. However, when determining the degree of startability of the engine 3, the engine water temperature TW and the altitude of the HV vehicle are determined. The above determination may be performed with only one of these, or another appropriate parameter may be employed as the startability parameter.

  In addition, the injector 4 of the embodiment is for a direct injection gasoline engine for a vehicle, but is not limited thereto, a port injection engine, a diesel engine, and an outboard motor in which a crankshaft is arranged vertically. It may be used for various industrial internal combustion engines such as marine vessel propulsion engines. In addition, the detailed configuration can be changed as appropriate within the scope of the gist of the present invention.

2 ECU (applying means, standby voltage setting means, control means and startability degree detecting means)
3 Internal combustion engine 4 Fuel injection valve 5 Motor 10 Drive circuit 11 Battery (power supply)
20 Booster circuit 61 Water temperature sensor (starting parameter detection means)
62 Atmospheric pressure sensor (starting parameter detection means)
63 Outside air temperature sensor (startability parameter detection means)
VB battery voltage
VC capacitor voltage
TW engine water temperature (startability parameter)
PA atmospheric pressure
TA outside temperature
AL HV vehicle altitude (startability parameter)
TWREF Predetermined temperature (threshold)
ALREF Predetermined altitude (threshold)
VR standby voltage
TUP boost time F_ENGSTART engine start flag

Claims (2)

A boosting control device for a fuel injection valve that controls boosting of a voltage applied to an electromagnetic fuel injection valve provided in an internal combustion engine,
A booster circuit for boosting the voltage of the power supply;
Applying means for applying a boosted voltage boosted by the booster circuit to the fuel injector in order to open the fuel injector;
Standby voltage setting means for setting at least a predetermined standby voltage to be held as the boosted voltage;
When the internal combustion engine is stopped, the boosting operation by the boosting circuit is stopped, and when the boosting voltage that gradually decreases with the internal combustion engine becomes equal to or lower than the set standby voltage, the boosting operation by the boosting circuit is resumed. Control means;
With
The boost voltage control device for a fuel injection valve, wherein the standby voltage setting means sets the standby voltage to be higher as the power supply voltage is lower. Startability parameter detecting means for detecting a startability parameter representing a degree of startability of the internal combustion engine, further comprising:
The control means performs predetermined normal boost control by the booster circuit when the detected startability parameter is a value representing a deterioration in startability with respect to a predetermined threshold value. The boost control device for a fuel injection valve according to claim 1.

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