JP2006291756A - Solenoid valve drive control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make residual magnetic force generated at a time of stop of excitation of a solenoid valve small. <P>SOLUTION: The solenoid valve 32 is used for a fuel injection valve 3 injecting and supplying fuel to an engine 1, and includes a valve element 32a and a core 32b attracting the valve element 32a by electromagnetic force generated by a coil, and influences on response of injection stop by intensity of residual magnetic force generated at a time of stop of excitation of the coil. The solenoid valve drive control device controlling excitation characteristics of the coil of the solenoid vale 32 according to an operation condition of the engine 1 is provided with a solenoid valve individual difference adjustment means setting excitation electric charge value before injection stop of excitation characteristics during injection to the minimum excitation electric charge value Ihc (Ihco) with which injection condition of the fuel injection valve 3 having the solenoid valve 32 mounted thereon can be maintained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solenoid valve drive control device, and is suitably applied to, for example, a drive control device for a solenoid valve used in a fuel injection valve that injects and supplies fuel to an internal combustion engine.

  Conventionally, as a fuel injection device for an internal combustion engine, for example, a device for injecting and supplying fuel into a cylinder of a diesel engine is known. In this apparatus, fuel is injected and supplied by an electromagnetic valve type fuel injection valve. This type of solenoid valve is a valve body that directly or indirectly drives a needle on the fuel injection valve main body that injects and stops fuel injection, and a suction member that sucks the valve body by electromagnetic force generated in a coil. A core is provided, and by controlling energization of the coil and energization stop, the needle is opened and closed to inject and stop the fuel injection.

  In recent years, there have been social demands for diesel engines to tighten exhaust gas regulations and reduce combustion noise. Correspondingly, there is a demand for high responsiveness of solenoid valves.

On the other hand, in the technique disclosed in Patent Document 1, the valve opening responsiveness is improved by flowing a transient current larger than the energizing current after the valve opening as the energizing characteristic to the solenoid valve during one injection. Yes. In this technology, the valve opening state is maintained and the power consumption is reduced by controlling the energization current after the valve opening to a predetermined constant current value.
Japanese Patent Laid-Open No. 8-17783

  The minimum current value for maintaining the valve opening has individual differences among the solenoid valves, and is different for each solenoid valve. However, in the prior art, since the predetermined constant current value is set to a value that is added to the margin current value, the residual magnetic force generated in the coil is increased when the power supply to the coil is stopped. There is a problem that the valve closing response time becomes slow.

  The present invention has been made in view of such circumstances, and an object of the present invention is to make it possible to reduce the residual magnetic force generated when the energization of the solenoid valve is stopped.

  Another object is to make it possible to reduce the residual magnetic force generated when the energization of the solenoid valve is stopped, and in the case of injection divided into a plurality of times in one combustion stroke, the proximity injection between the pre-injection and the post-injection It is an object of the present invention to provide an electromagnetic valve drive control device that can prevent injection overlap due to the above.

  In order to achieve the above object, the present invention comprises the following technical means.

The invention according to any one of claims 1 to 6 is used in a fuel injection valve for injecting and supplying fuel to an internal combustion engine, and includes a valve body and a suction member that sucks the valve body by electromagnetic force generated in the coil. Solenoid valve driving control that controls the response characteristics of injection stop by the magnitude of the residual magnetic force generated when the energization of the engine is stopped, and controls the energization characteristics of the coil of the solenoid valve according to the operating state of the internal combustion engine In the device
Among the energization characteristics during one injection, there is provided an electromagnetic valve individual difference adjusting means for setting the energized charge value before injection stop to the minimum energized charge value that can maintain the injection state of the fuel injection valve on which the solenoid valve is mounted. It is characterized by being.

  Thus, the energized charge value that can maintain the injection state before the injection stop can be set to the minimum energized charge value unique to the solenoid valve mounted on the fuel injection valve, and the residual generated when the energization of the coil is stopped. The magnitude of the magnetic force can be reduced regardless of individual differences between the solenoid valves.

In the invention according to claim 2 of the present invention, the electromagnetic valve individual difference adjusting means is
Holding charge value changing means for changing the energized charge value before stopping the injection from the holding charge value that holds the injection state regardless of individual differences of the solenoid valves;
Determining means for detecting an operating state of the internal combustion engine and determining whether or not the rotational fluctuation of the internal combustion engine is equal to or greater than a predetermined value based on the operating state;
When the energized charge value before stopping the injection is gradually changed from the held charge value and it is determined that the rotational fluctuation is a predetermined value or more, the energized charge value is set to the minimum energized charge value.

  According to this, as a method of setting the minimum energized charge value before injection stop unique to the solenoid valve mounted on the fuel injection valve, initially, before the adjustment, the energized charge value before injection stop is related to the individual difference of the solenoid valve. First, the held charge value for holding the injection state is set, and gradually changed from the held charge value, and the energized charge value when the rotational fluctuation becomes a predetermined value or more is determined as the minimum energized charge value. As a result, the predetermined value is set to a rotational fluctuation that does not affect the performance of the internal combustion engine, thereby affecting the responsiveness of the injection stop when the fuel injection valve having the electromagnetic valve is mounted on the internal combustion engine. The magnitude of the residual magnetic force can be adjusted to be small.

  In the invention according to claim 3 of the present invention, the minimum energized charge value can be obtained by adding a charge value specific to the solenoid valve to the energized charge value when it is determined that the rotational fluctuation is equal to or greater than a predetermined value. It is said.

  According to this, it is preferable that the minimum energized charge value is obtained by adding a charge value unique to the solenoid valve to the energized charge value when it is determined that the rotational fluctuation is equal to or greater than a predetermined value. As a result, the minimum energized charge value before the injection stop inherent to the solenoid valve mounted on the fuel injection valve can be set to the minimum value at which the injection state is reliably maintained.

In the invention according to claim 4 of the present invention, the energization characteristic is such that an energization pulse corresponding to the injection period during one injection is formed,
The period for setting the minimum energized charge value is characterized in that it is set to a predetermined time regardless of the energization pulse length in the region before injection stop in the energization pulse.

  In general, the injection amount of fuel supplied from the fuel injection valve to the internal combustion engine is adjusted by the energization period of the coil, that is, the energization pulse width, and the energization pulse width is the optimum injection according to the operating state of the internal combustion engine. Since it is determined according to the amount, the stability of the fuel injection characteristics is required even if the injection amount requirement changes.

  On the other hand, in the invention according to claim 4, the period for setting the minimum energization charge value is limited to a predetermined time regardless of the energization pulse length in the region before the injection stop in the energization pulse. Even when the amount request changes, particularly when a small injection amount is required, it is possible to ensure the stability of the fuel injection characteristics.

  Further, in the invention according to claim 5 of the present invention, the holding time changing means for changing the predetermined time from the holding time for holding the injection state regardless of the individual difference of the electromagnetic valve, and the operating state of the internal combustion engine are detected. Determining means for determining whether or not the rotational fluctuation of the internal combustion engine is greater than or equal to a predetermined value based on the operating state, and gradually changing the predetermined time from the holding time to determine that the rotational fluctuation is greater than or equal to the predetermined value. In this case, the predetermined time is set as the maximum holding time unique to the solenoid valve.

  According to this, as a method for setting the predetermined time, when the rotation fluctuation is determined to be greater than or equal to a predetermined value by gradually changing from the holding time for holding the injection state regardless of individual differences of the electromagnetic valves, the predetermined time Is preferably the maximum holding time specific to the solenoid valve. As a result, the current-carrying charge state inherent to the solenoid valve mounted on the fuel injection valve before the injection stop is determined, and the minimum current-carrying charge value that maintains the injection state as much as possible and the longest holding time for maintaining the minimum current-carrying charge value It can be. Therefore, it is possible to accurately reduce the magnitude of the residual magnetic force that affects the responsiveness of stopping the injection.

Moreover, in invention of Claim 6 of this invention, the solenoid valve drive control apparatus as described in any one of Claims 1-5 is inject | poured several times during one combustion stroke according to the driving | running state. In the operation region in which at least the proximity injection is performed between the pre-injection in which the injection is performed first and the post-injection in which the injection is performed after the pre-injection among the plurality of injections.
Of the energization characteristics corresponding to the pre-injection, the energized charge value before the injection stop is set to the minimum energized charge value.

  According to this, in the case of performing at least close injection of the pre-injection that performs the injection first and the post-injection that performs the injection after the pre-injection among the plurality of injections, the injection stop of the energization characteristics corresponding to the pre-injection It is preferable to set the previous energized charge value to the minimum energized charge value.

  If energization for the post-injection is started while the residual magnetic force generated when the injection is stopped remains in the pre-injection or the injection state of the fuel injection valve is maintained due to the influence of the residual magnetic force, the post-injection injection The start may be accelerated, and as a result, a phenomenon may occur in which the pre-injection and the post-injection overlap.

  On the other hand, in the invention according to claim 6, the energization charge value before the stop of the injection among the energization characteristics corresponding to the pre-injection is set to the minimum energization charge value. It is possible to prevent the residual state of the pre-injection from remaining until it is started, or the fuel injection valve from continuing the injection state due to the influence of the residual force. Therefore, it is possible to prevent the overlapping of the injection by the proximity injection of the pre-injection and the post-injection.

  Hereinafter, embodiments in which the electromagnetic valve drive control device of the present invention is applied to an accumulator fuel injection control device will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a configuration diagram showing the overall configuration of a fuel injection control device to which the electromagnetic valve drive control device of the present embodiment is applied. FIG. 2 is a schematic cross-sectional view of a fuel injection valve equipped with the electromagnetic valve in FIG. FIG. 3 is a flowchart showing a control method for controlling energization characteristics for energizing the coil of the solenoid valve in the ECU shown in FIG. FIG. 4 is a time chart showing the relationship among the injection signal, the energization characteristic of the electromagnetic valve, and the injection characteristic of the fuel injection valve. 5 and 6 are graphs for explaining the operational effects of the present embodiment. FIG. 5 shows the relationship between the residual magnetic force and the energized charge value, and FIG. 6 shows the relationship between the valve closing start time and the residual magnetic force. It is a graph to show.

  An accumulator fuel injection device (hereinafter referred to as a common rail fuel injection device) is a fuel injection system that injects and supplies fuel to, for example, a diesel engine (hereinafter referred to as an engine) 1. As shown in FIG. 1, the common rail type fuel injection device includes a common rail 2 as a pressure accumulator for storing high-pressure fuel, a fuel injection valve 3 for injecting and stopping injection by driving an electromagnetic valve 32, and a high-pressure fuel. A supply pump 4 as a fuel supply pump for pumping and a control device (hereinafter referred to as ECU) 5 as a control means for controlling them are configured.

  The engine 1 includes a plurality of cylinders that continuously perform intake, compression, expansion, and exhaust strokes as a combustion cycle. FIG. 1 shows a four-cylinder engine as an example. It may be an engine having

  The common rail 2 is a pressure accumulator that accumulates high-pressure fuel supplied to the fuel injection valve 3, and the high-pressure fuel is supplied via a fuel pipe 6 serving as a high-pressure fuel flow path so that a common rail pressure corresponding to the fuel injection pressure is accumulated. Is connected to the discharge port of the supply pump 4 for pressure feeding. The high-pressure fuel supplied to the fuel injection valve 3 is discharged from the fuel injection valve 3 using a part of surplus fuel or the like as leak fuel, and the leak fuel from the fuel injection valve 3 is a relief pipe as a fuel return path. 7 is returned to the fuel tank 8.

  A pressure limiter 11 is attached to a relief pipe 9 from the common rail 2 to the fuel tank 8. The pressure limiter 11 is a pressure safety valve, and is configured to open when the fuel pressure in the common rail 2 exceeds the limit set pressure, and suppresses the fuel pressure in the common rail 2 to be equal to or lower than the limit set pressure.

  The fuel injection valve 3 is mounted for each cylinder of the engine 1 and supplies fuel into the cylinder. The fuel injection valve 3 is connected to the downstream ends of a plurality of high-pressure fuel pipes 10 branched by the common rail 2 and accumulates pressure in the common rail 2. The supplied high-pressure fuel is injected into each cylinder. The fuel injection valve 3 is an electromagnetic valve type fuel injection valve that performs fuel injection and stops injection by controlling the operation of the electromagnetic valve 32. Specifically, as shown in FIG. 2, the fuel injection valve 3 includes an injection hole 38 for injecting fuel, a needle 33 as a valve member that blocks and allows fuel injection from the injection hole 38, A control pressure chamber 31 for lifting the needle 33 by the fuel pressure and an electromagnetic valve 32 for increasing / decreasing the fuel pressure in the control pressure chamber 31 are configured. The needle 33 closes and opens as the fuel pressure in the control pressure chamber 31 controlled by the electromagnetic valve 32 increases or decreases. Thus, the needle is not limited to being indirectly driven by the electromagnetic valve 32, and the needle 33 may be directly driven by the electromagnetic valve 32.

  The electromagnetic valve 32 is driven by electromagnetic force generated in the coil, and includes a valve body 32a and a fixed core 32b as a suction member that sucks the valve body 32a with electromagnetic force generated in the coil. In the electromagnetic valve 32, when energization to the coil is stopped and the coil is not excited, no magnetic attractive force is generated in the fixed core 32b, so the valve body 32a is seated on a valve seat (not shown). In this case, the communication between the control chamber 31 and the fuel circulation path 7 on the fuel tank 8 side is cut off, and the fuel pressure in the control chamber 31 becomes the same as the common rail pressure guided to the nozzle chamber 37. The needle 31 is pressed against the nozzle seat 38 with the same fuel pressure as the common rail pressure and closes.

  When energization of the coil is stopped, residual magnetic force is generated according to the magnitude of the energized charge value (hereinafter referred to as energization current) during energization (see FIG. 5). This residual magnetic force acts between the fixed core 32b and the valve body 32a, delays the valve closing start timing of the electromagnetic valve 32 (see FIG. 6), and affects the valve closing response. And the valve closing start time of the needle 31 is delayed, and the response of injection stop is affected.

  On the other hand, when the coil is energized and the coil is excited, a magnetic attraction force is generated in the fixed core 32b, and the attraction force acts on the valve body 32a, so that the valve body is attracted and separated from the valve seat. Yes. In this case, the control chamber 31 and the fuel circulation path 7 communicate with each other via the orifice 34, and the fuel pressure in the control chamber 31 is reduced. This pressure reduction reduces the pressing force of the needle 31 toward the nozzle seal 38, so that the needle 31 is separated from the nozzle seat 38 and opened. The pressure reduction speed is set according to the size of the orifice 34.

  The supply pump 4 is a pump that pumps high-pressure fuel to the common rail 2. Specifically, the supply pump 4 includes a feed pump that sucks the fuel in the fuel tank 8 into the supply pump 4 and a high-pressure pump that compresses the fuel sucked up by the feed pump to a high pressure and pumps it to the common rail 2. The feed pump and the high-pressure pump are driven by a common camshaft 12. The camshaft 12 is rotationally driven by the crankshaft 13 of the engine 1 or the like.

  The supply pump 4 is equipped with a metering control valve (not shown) that adjusts the amount of fuel sucked into the high-pressure pump, that is, the discharge amount that is high-pressure pumped to the common rail 2. The common rail pressure is adjusted by being controlled by the ECU 5.

  The ECU 5 is a CPU for performing control processing and arithmetic processing, a storage device (ROM, standby RAM or EEPROM, memory such as RAM) for storing various programs and data, an input circuit, an output circuit, a power supply circuit, and an electromagnetic of the fuel injection valve 3. A micro of a well-known structure configured to include functions such as a drive circuit for the valve 32 (hereinafter referred to as an electromagnetic valve drive circuit) and a drive circuit for a metering control valve of the supply pump 4 (hereinafter referred to as a pump drive circuit). A computer is provided. Various arithmetic processes are performed based on sensors signals read into the ECU 5. In the ECU 5 in FIG. 1, reference numeral 51 denotes a control unit including a CPU, a storage device, an input circuit, an output circuit, etc., 52 denotes an electromagnetic valve drive circuit, and 53 denotes a pump drive circuit.

  As shown in FIG. 1, the sensors connected to the ECU 5 include an accelerator sensor 21 that detects the accelerator opening degree Accp, a rotation speed sensor 22 that detects the engine rotation speed Ne, and a water temperature that detects the cooling water temperature Tw of the engine 1. There are a sensor 23, a fuel pressure sensor (hereinafter referred to as a common rail pressure sensor) 24 for detecting a common rail pressure Pc, and other sensors 25.

  As shown in FIG. 1, the solenoid valve drive circuit 52 in the ECU 5 includes a charge circuit 52 a that stores and increases a battery voltage from an in-vehicle battery (not shown) as an in-vehicle power source, a discharge control switching element 52 b, and a discharge A discharge control circuit 52c for intermittently controlling the control switching element 52b. These configurations constitute a transient current generating circuit (hereinafter referred to as a maximum current generating circuit) that instantaneously applies a high voltage and a large current to the solenoid valve 52.

  As shown in FIG. 3, the initial maximum current generating circuit is configured such that a solenoid valve is operated in a drive pulse section (hereinafter referred to as a transient current drive pulse section) Tp corresponding to an energization start portion of the drive signal Tinj during one injection. The energization characteristic to 32 is formed in a transient current waveform having a peak current value of Ip. More specifically, when the discharge control circuit 52c receives the drive signal output from the control unit 51, the discharge control circuit 52c turns on the discharge control switching element 52b to start energization of the electromagnetic valve 32, and thereafter, a current (not shown) When the energization current value detected by the detection unit reaches a predetermined threshold value (for example, discharge stop threshold value Ip), the transient current waveform transient current is supplied to the solenoid valve 32 by turning off the discharge control switching element 52b. To do.

  Further, the solenoid valve drive circuit 52 includes a constant current control circuit (not shown). The constant current control circuit supplies a transient current to the solenoid valve 32, and then, as shown in FIG. In the drive pulse section (hereinafter referred to as a holding current drive pulse section) Tp corresponding to the latter half portion of the power supply current characteristic, the energizing current characteristic is divided into a plurality of levels of current values held in a constant current state (two stages in this embodiment). To switch to. A holding current having a constant constant current value (in this example, two-stage current values of Ih and Ihc shown in FIG. 3) is supplied to the solenoid valve 32. Here, the current waveform of the current value Ih is referred to as a first holding current, and the current waveform of the current value Ihc is referred to as a second holding current.

  Here, the ECU 5 includes an injection unit that controls the injection operation of the fuel injection valve 3, and the injection unit includes a target injection amount determination unit, an injection timing determination unit, an injection period determination unit, and a fuel. And injection valve driving means. The target injection amount determining means determines an optimal target injection amount Qfin according to the operating state of the engine 1 detected by various sensors. The injection timing determining means determines a command injection timing (energization pulse timing) Tfin based on the target injection amount Qfin and the engine speed Ne. The injection period determining means determines a command injection period (energization pulse time) Tinj based on the common rail pressure Pc and the target injection amount Qfin.

  The fuel injection valve driving means applies a substantially pulsed energization current to the electromagnetic valve 32 of the fuel injection valve 3 of each cylinder until the injection command pulse time (Tinj) elapses from the command injection timing (Tfin). . More specifically, the fuel injection valve driving means includes a peak current waveform generating means for controlling the current supply characteristic to the electromagnetic valve 32 to a transient current value Ip, and a two-stage holding current for the current supply characteristic to the electromagnetic valve 32. Holding current waveform generating means for performing constant current control to Ih and Ip.

  The holding current waveform generating means includes electromagnetic valve individual difference adjusting means, and the electromagnetic valve individual difference adjusting means has holding current value changing means and determination means. The holding current value changing means temporarily sets the second holding current value Ihc with the corrected holding current value Ihi (see FIG. 3) changed from the first holding current value Ih in order to determine the second holding current. The determination means determines the influence on the operating state of the engine 1 when the solenoid valve 32 is energized and controlled with the corrected holding current Ihi changed from the first holding current value Ih. The second holding current value Ihc corresponds to the energized charge value before stopping the injection described in the claims.

  Next, a control method for the accumulator fuel injection apparatus having the above-described configuration, particularly a control method for controlling the energization characteristics of the coil of the electromagnetic valve 32 in order to control the injection operation of the fuel injection valve 3, will be described with reference to FIG. To do. As shown in FIG. 4, in S301 (S is a step), the first holding current value Ih is read, and the corrected holding current value Ihi for determining the second holding current value Ihc is initialized with the first holding current value Ih. To do. In addition, an energization period (hereinafter referred to as a second holding current energization period) Thc energized at the second holding current value Ih is initialized to a predetermined energization time.

  In S302, in order to gradually change the corrected holding current value Ihi, the corrected holding current value Ihi is reduced by a predetermined current value ΔI, and the solenoid valve 32 is energized and controlled with the corrected holding current Ihi. In S303, the fluctuation ΔNe of the engine speed Ne at this time is measured.

  In S304, it is determined whether or not the rotational fluctuation ΔNe has reached a predetermined value ΔNa. When the rotational fluctuation ΔNe does not reach the predetermined value ΔNa, the magnitude of the corrected holding current value Ihi that is gradually changed is the minimum holding current value (specific to the solenoid valve 32 mounted on the engine 1) ( Ihco) is not reached, and the process returns to S302. On the other hand, when the rotational fluctuation ΔNe has reached the predetermined value ΔNa, the process proceeds to S305. The predetermined value ΔNa is set to a rotational fluctuation amount for determining that the engine 1 is affected by the injection state of the fuel injected from the fuel injection valve 3 having the electromagnetic valve 32. When the predetermined value ΔNa is reached, the injection amount starts to vary from the fuel injection valve 3 by energization control to the electromagnetic valve 32.

  In S305, the corrected holding current value Ihi at that time is determined as the minimum energization current value (referred to as holding limit current value) Ihco that can hold the injection state of the fuel injection valve 3 before the stop of injection, and the holding limit current value Ihco is determined as the corrected holding current value Ihi (Ihco = Ihi).

  In S306, a value obtained by adding a current value unique to the solenoid valve 32 (hereinafter referred to as a margin current value) di to the holding limit current value Ihco determined in S305 is set as a required holding current value, and set as the second holding current value Ihc. To do.

  In S307, on the premise of the determined second holding current value Ihc, the corrected holding current energizing period Tchi is gradually changed to change the corrected holding current energizing period Tchi for determining the second holding current energizing period Thc. The electromagnetic valve 32 is energized and controlled during the corrected holding current energization period Tchi. In S308, the fluctuation ΔNe of the engine speed Ne at this time is measured.

  In S304, it is determined whether or not the rotational fluctuation ΔNe has reached a predetermined value ΔNa. When the rotational fluctuation ΔNe does not reach the predetermined value ΔNa, the magnitude of the correction holding current energization period Tchi that is gradually changing is the maximum holding current energization unique to the solenoid valve 32 mounted on the engine 1. It is determined that the period (Thco) has not been reached, and the process returns to S307. On the other hand, when the rotational fluctuation ΔNe has reached the predetermined value ΔNa, the process proceeds to S309.

  In S309, the corrected holding current energizing period Tchi at that time is determined as the maximum energizing period (referred to as a holding limit energizing period) Thco that can maintain the injection state of the fuel injection valve 3 before the injection stop, and the holding limit energizing period. Thco is determined as the corrected holding current conduction period Tchi (Thco = Thci).

  In S310, a holding current correction period in which a value obtained by subtracting an energization period (hereinafter referred to as a margin energization period) di unique to the solenoid valve 32 to the holding limit energization period Thco determined in S309 is switched to the second holding current value Ihc. And set as the second holding current energization period Thc.

  Here, the control process of S302 constitutes the holding current value changing means. The control process in S304 constitutes the determination means. The control processing from S301 to S306 constitutes the individual solenoid valve difference adjusting means described in the claims. Further, the control processing from S307 to S310 may be included in the electromagnetic valve individual difference adjusting means.

  By the above control method, as the current-carrying characteristics to the solenoid valve 32, the current-carrying current value before the injection stop in the current waveform composed of the transient current and the first holding current value Ih is used as the engine 1 in which the solenoid valve 32 is mounted. Is determined to be the minimum energization current value (holding limit current value Ihco) that can hold the injection state determined based on the operating state, and the solenoid valve 32 is energized with the second holding current value Ihc corresponding to the holding limit current value Ihco. Be controlled. Therefore, the magnitude of the residual magnetic force generated when the energization of the electromagnetic valve 32 is stopped can be reduced regardless of the individual difference of the electromagnetic valves 32.

  The current-carrying current value before stopping the injection in the prior art is set to a holding current value Ih (corresponding to the first holding current value in this embodiment) that can hold the injection state regardless of individual differences of the solenoid valves 32. On the other hand, in the present embodiment, the holding limit current value Ihco that can hold the injection state is determined based on the actual solenoid valve 32 mounted on the electromagnetic valve 32, and the second holding current value Ihc corresponding to this is determined. Since energization control of the solenoid valve 32 is performed, the magnitude of the residual magnetic force can be reduced as shown in FIG. 5 (see FIG. 5), and the valve closing start time Tdc of the solenoid valve 32 shown in FIG. 4 can be shortened (see FIG. 6). Therefore, the valve closing response of the electromagnetic valve 32 can be improved. As a result, as shown by the characteristic of the injection rate q in FIG. 4, the response of stopping fuel injection can be improved as compared with the conventional characteristic indicated by the broken line.

  Since the second holding current value Ihc is obtained by adding the marginal current value di inherent to the solenoid valve 32 to the holding limit current value Ihco, the second holding current value Ihc can be set to the minimum energization current value that can reliably hold the injection state. .

  Furthermore, on the premise of the determined second holding current value Ihc, the energization period set by the second holding current value Ihc is substantially set to the maximum energization period (holding limit energization period Thco) that can maintain the injection state. The energization of the solenoid valve 32 is controlled in the second holding current energizing period Thc corresponding to the holding limit energizing period Thco.

  Next, the operation and effect of the present embodiment will be described. (1) In the present embodiment, as a method of controlling the energization characteristic to the solenoid valve 32, among the energized current waveform composed of the transient current and the first holding current value Ih. Is determined to be the minimum energizing current value (holding limit current value Ihco) that can maintain the injection state in the engine 1 in which the solenoid valve 32 is actually mounted, and corresponds to the holding limit current value Ihco. The energization characteristic to the solenoid valve 32 is controlled by the second holding current value Ihc.

  The current-carrying current value before stopping the injection in the prior art is set to a holding current value Ih (corresponding to the first holding current value in this embodiment) that can hold the injection state regardless of individual differences of the solenoid valves 32.

  On the other hand, in the present embodiment, the holding limit current value Ihco that can hold the injection state is determined based on the actual solenoid valve 32 that is mounted on the solenoid valve 32, and the second holding current value Ihc corresponding to this is determined. Since the valve 32 is energized and controlled, the magnitude of the residual magnetic force can be reduced regardless of the individual differences of the electromagnetic valves 32. As a result, the valve closing start time Tdc of the electromagnetic valve 32 can be shortened, so that the valve closing response of the electromagnetic valve 32 can be improved. For example, at the injection rate q, the response of stopping fuel injection can be improved compared to the conventional characteristics.

  (2) In the present embodiment, the holding current value changing means for gradually changing the holding current value Ih to be smaller than the first holding current value Ih and the operating state of the engine 1 are detected, and the engine rotation fluctuation ΔNe is determined based on this operating state. Determination means for determining whether or not the value (ΔNa) or more exists. As a result, when the solenoid valve 32 is energized and controlled with the corrected holding current Ihi that is gradually changed smaller than the first holding current value Ih, and it is determined that the rotational fluctuation ΔNe has reached a predetermined value (ΔNa), The corrected holding current Ihi can be determined as the holding limit current value Ihco.

  Therefore, by setting the predetermined value ΔNe to a rotational fluctuation that does not affect the performance of the engine 1, the fuel injection valve 3 having the electromagnetic valve 32 is influenced by the injection stop response when the engine 1 is mounted. It is possible to adjust so as to reduce the magnitude of the residual magnetic force.

  (3) Furthermore, in the present embodiment, the second holding current value Ihc is preferably a value obtained by adding the margin current value ΔI inherent to the solenoid valve 32 to the holding limit current value Ihco. Thereby, the energization current value before stopping the injection can be set to the minimum energization current value that can reliably maintain the injection state.

  (4) In the present embodiment, the second holding current energization period Thc for setting the second holding current value Ihc is set to the length of the energization pulse period Tinj in the region before injection stop in the drive signal (energization pulse). Regardless, it is set to a predetermined period (predetermined time).

  In general, the injection amount of fuel supplied from the fuel injection valve 3 is adjusted by the energization pulse width Tinj, and the energization pulse width is determined corresponding to the optimal injection amount according to the operating state of the engine 1. Therefore, the stability of fuel injection characteristics is required even when the injection amount requirement changes.

  On the other hand, in the present embodiment, the second holding current energization period Thc is limited to a predetermined time regardless of the length of the energization pulse Tinj, so that the injection amount request changes, particularly when a small injection amount is required. Even so, it is possible to ensure the stability of the fuel injection characteristics.

  (5) Further, as a method of setting the predetermined time, the electromagnetic valve 32 is set to the corrected holding current energization period Tchi gradually changed from the predetermined holding time for holding the injection state regardless of individual differences of the electromagnetic valves 32. When energization control is performed and it is determined that the rotation fluctuation Ne has reached a predetermined value, the corrected holding current energization period Tchi is preferably set to the maximum holding time unique to the solenoid valve 32. As a result, the energization current state before the injection stop inherent to the solenoid valve 32 mounted on the fuel injection valve 3 is changed to the second holding current value Ihc defined by the holding limit current value Ihco that holds the injection state as much as possible. The longest holding time Thc for maintaining the second holding current value Ihc can be set. Therefore, it is possible to accurately reduce the magnitude of the residual magnetic force that affects the responsiveness of stopping the injection.

(Second Embodiment)
Hereinafter, other embodiments to which the present invention is applied will be described. In the following embodiments, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and description thereof will not be repeated.

  In the second embodiment, as shown in FIG. 7, the ECU 5 has injection means for injecting a plurality of times (in this embodiment, twice) during one combustion stroke according to the operating state of the engine 1. FIG. 7 is a time chart showing the relationship between the energization characteristic to the solenoid valve and the injection characteristic of the fuel injection valve according to the embodiment. FIG. 7 shows a case in which the pre-injection in which the injection is performed first and the post-injection in which the injection is performed after the pre-injection among the plurality of injections are made close to each other. An example is shown and the characteristic of the broken line shows an example of the prior art.

  In general, for the post-injection, the residual magnetic force generated when the injection is stopped remains in the pre-injection or the injection state of the fuel injection valve 3 is maintained by the influence of the residual magnetic force (see the broken line characteristics in the figure). When the energization is started, there is a possibility that the start of post-injection may be accelerated as shown by the broken line characteristics of the hatched frame in the drawing. As a result, a phenomenon may occur in which the pre-injection and the post-injection overlap. In a state where such a phenomenon occurs, the injection start timing of the post-injection fluctuates within the hatched frame in the drawing, and there is a possibility that the injection amount of the post-injection varies.

  On the other hand, in the present embodiment, in the case where the pre-injection and the post-injection are at least closely injected, the energization current value before the stop of the injection among the energization characteristics corresponding to the pre-injection can be maintained. The second holding current value Ihc defined by the value Ihco is set. Thereby, it is possible to prevent the residual magnetic force of the pre-injection from remaining immediately before the energization for the post-injection is started or the injection state of the fuel injection valve 3 from being continued due to the influence of the residual magnetic force. It is.

  In other words, the magnetic force with which the fixed core 32b attracts and holds the valve element 32a at the end of injection is greater than the necessary attraction force for a solid (plus-side variation solid) that generates a large magnetic force by the same current flow. The magnetic force was generated. On the other hand, the residual magnetic force can be reduced by adjusting the minus so that the required amount of the attractive magnetic force is secured by the above-described energization current setting at the injection end timing as the present technology. As a result, it is possible to prevent the overlapping of the injection by the proximity injection of the pre-injection and the post-injection.

  In addition, in the comparison of the attractive magnetic force at the injection end timing in the plus-side variation solids described above and the attractive magnetic force at the injection end timing in the adoption of the present technology, the adoption of the present technology actually ends the injection from the injection end command. It is possible to set a short injection end delay, which is the time until the start. As a result, regarding the interval time between injections from the end of the pre-injection to the start of the post-injection, in the comparison in which both the conventional and the present technology are set to the same target time, the adoption of the present technology is more The time between can be set short. This has the effect of contributing to improving the overall performance of output and emissions in recent years.

(Other embodiments)
In the present embodiment described above, the fuel injection valve 3 equipped with the electromagnetic valve 32 is indirectly controlled by the needle 33 by the increase / decrease of the fuel pressure in the control pressure chamber 31 controlled by the electromagnetic valve 32, thereby injecting fuel. However, the needle 33 may be directly driven by the electromagnetic valve 32 as well as the needle 33 that is indirectly driven by the electromagnetic valve 32.

It is a block diagram which shows the whole structure of the fuel-injection control apparatus to which the solenoid valve drive control apparatus of the 1st Embodiment of this invention is applied. It is typical sectional drawing of the fuel injection valve which mounts the solenoid valve in FIG. 2 is a flowchart illustrating a control method for controlling energization characteristics of energizing a coil of an electromagnetic valve in the ECU in FIG. 1. It is a time chart which shows the relationship between the injection signal, the electricity supply characteristic to a solenoid valve, and the injection characteristic of a fuel injection valve. It is a graph explaining the effect of 1st Embodiment. It is a graph explaining the effect of 1st Embodiment. It is a time chart which shows the relationship between the electricity supply characteristic to the solenoid valve concerning 2nd Embodiment, and the injection characteristic of a fuel injection valve.

Explanation of symbols

1 engine (internal combustion engine)
2 Common rail (accumulator that stores high-pressure fuel supplied to the fuel injection valve)
3 Fuel injection valve 4 Supply pump (fuel supply pump)
5 ECU (control device)
24 Common rail pressure sensor (fuel pressure sensor)
31 Control pressure chamber 32 Solenoid valve 32a Valve body 32b Fixed core (core, suction member for sucking valve body by electromagnetic force generated in coil)
33 Needle (Valve member)
36 Nozzle seat (valve seat)
38 nozzle hole

Claims (6)

Used in a fuel injection valve that injects fuel into an internal combustion engine, and has a valve body and a suction member that sucks the valve body with electromagnetic force generated in the coil, and has a residual magnetic force generated when energization of the coil is stopped. An electromagnetic valve that influences the response of injection stop depending on the size, and in the electromagnetic valve drive control device that controls the energization characteristic to the coil of the electromagnetic valve according to the operating state of the internal combustion engine.
Solenoid valve individual difference adjustment that sets the energized charge value before the injection stop of the energization characteristics during one injection to the minimum energized charge value that can maintain the injection state of the fuel injection valve on which the solenoid valve is mounted. An electromagnetic valve drive control device characterized by comprising means. The electromagnetic valve individual difference adjusting means is
Holding charge value changing means for changing the energized charge value before stopping the injection from the holding charge value holding the injection state regardless of individual differences of the solenoid valves;
Determining means for detecting an operating state of the internal combustion engine, and determining whether or not the rotational fluctuation of the internal combustion engine is greater than or equal to a predetermined value based on the operating state;
When the energized charge value before stopping the injection is gradually changed from the held charge value, and it is determined that the rotational fluctuation is equal to or greater than a predetermined value, the energized charge value is set to the minimum energized charge value. The electromagnetic valve drive control device according to claim 1, wherein   The solenoid valve drive according to claim 2, wherein the minimum energized charge value is obtained by adding a charge value unique to the solenoid valve to an energized charge value when it is determined that the rotational fluctuation is equal to or greater than a predetermined value. Control device. In the energization characteristic, an energization pulse corresponding to an injection period during the one injection is formed,
The period for setting the minimum energization charge value is set to a predetermined time in the region before injection stop in the energization pulse regardless of the energization pulse length. The electromagnetic valve drive control device according to any one of the above. Holding time changing means for changing the predetermined time from a holding time for holding the injection state regardless of individual differences of the solenoid valves;
Determining means for detecting an operating state of the internal combustion engine, and determining whether or not the rotational fluctuation of the internal combustion engine is greater than or equal to a predetermined value based on the operating state;
The predetermined time is gradually changed from the holding time, and when it is determined that the rotation fluctuation is greater than or equal to a predetermined value, the predetermined time is set as a maximum holding time unique to the solenoid valve. 5. The electromagnetic valve drive control device according to 4. The electromagnetic valve drive control device according to any one of claims 1 to 5 is used for the fuel injection valve that injects a plurality of times during one combustion stroke according to the operation state,
In the operation region in which the operation state causes at least a close injection of a pre-injection that performs the injection first in the plurality of injections and a post-injection that performs the injection after the pre-injection
The solenoid valve drive control device, wherein an energization charge value before injection stop in the energization characteristic corresponding to the pre-injection is set to the minimum energization charge value.

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