JP2004278411A - Driving device of solenoid valve for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injector driving device capable of realizing an excellent property of fuel injection quantity at low cost even if there exist variations of wire resistance, etc., from an electromagnetic coil or the driving device to the injector. <P>SOLUTION: Time while voltage supply switches from a first power source to a second power source is actively stabilized by controlling pre-energizing current. Fuel flow, maximum operating fuel pressure, and other properties of the injector can be improved without reducing tolerance of the injector and its driving circuit. As the tolerance can be enlarged if the properties are the same, the injector and its driving circuit can be manufactured at low cost. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel injection valve, and more particularly, to a fuel injection valve control device and its software.
[0002]
[Prior art]
2. Description of the Related Art Some engines that obtain power by burning fuel, particularly internal combustion engines, supply and control pressurized fuel to the engine by a fuel injection valve (hereinafter, referred to as an injector) in order to control the combustion and operation of the engine. As a principle of operation of the injector, a type in which a fuel control valve is opened and closed using a magnetic force of an electromagnetic coil is generally used. Since the flow rate of fuel injected from the injector is mainly determined by the pressure difference between the fuel and the downstream of the valve and the valve opening time, the magnetic force of the electromagnetic coil must be quickly and accurately controlled. As a means for quickly generating an effective magnetic force, it is known to adjust the value of the current flowing through the electromagnetic coil to a value that is not yet sufficient to operate the valve before the actual control (for example, see Patent Reference 1). In addition, two types of power supplies are provided, and the first power supply voltage, which is a large voltage, is applied at the initial stage of driving to quickly start the current of the electromagnetic coil, and thereafter, a second power supply voltage of a lower power supply voltage is supplied, and It is also common to reduce the current decrease delay when the valve is closed by switching to and holding a low current value.
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 55-040391
[Problems to be solved by the invention]
However, the resistance value of the electromagnetic coil, the number of turns, and the characteristics of the magnetic circuit, that is, the inductance of the magnetic coil vary due to restrictions on the manufacture of the injector. This has caused variations in the time from the start of energization to the full opening, and thus variations in the fuel injection amount. Further, it is extremely difficult and expensive to manufacture an electromagnetic coil having a very accurate resistance value and inductance.
[0005]
It is an object of the present invention to realize a good fuel injection amount characteristic even if there is a variation in a wiring resistance from an electromagnetic coil or a driving device to an injector in an injector driving device, and to realize the same at low cost. .
[0006]
[Means for Solving the Problems]
An object of the present invention is a device for opening and closing a solenoid valve with a drive circuit from a power source, the device having at least two power supply voltages, detecting means for detecting a current flowing through the solenoid valve, and switching from a first power supply voltage to a second power supply voltage. A solenoid valve current switching threshold value, a means for comparing the current detection value detected by the detection means with the current switching threshold value, and starting driving with a first power supply voltage, so that the solenoid valve current becomes Power supply voltage switching means for switching to the second power supply voltage after the threshold value is exceeded; control means for holding current for holding the solenoid valve open after switching to the second power supply voltage; and first power supply voltage. First power supply time detection means for detecting the time from the start of application to the end thereof or the start of the first holding current, and a current of such a magnitude that the solenoid valve does not completely respond yet. The first power supply Pre-current supply means for supplying the pre-current before applying pressure, first power supply time comparison means for comparing the first power supply time with a reference value of the first power supply time, and the pre-current supply based on the comparison result. The problem is solved by a drive device for a solenoid valve for an internal combustion engine, characterized by having a pre-current adjusting means for adjusting the time.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in detail with reference to the drawings with reference to the exemplary embodiments.
[0008]
The control target of the embodiment is an electromagnetic coil of an injector in an internal combustion engine. This injector generally has a fuel flow path through which fuel passes, an orifice that keeps the amount of fuel per injection time constant, a plunger valve that allows fuel to pass only when necessary, and shuts off the rest, and a plunger valve when power is not supplied. The main structure is a return spring for closing the valve and an electromagnetic coil for attracting the plunger valve by magnetic force when energized. When the pressure difference between the upstream and downstream of the plunger valve is constant, this injector takes advantage of the fact that the fuel injection amount per injection is determined according to the time that the plunger valve is open, and the fuel supply amount of the internal combustion engine is determined. Used for control.
[0009]
FIG. 1 schematically shows a typical control method of an internal combustion engine to which the present invention is applied. This is a piston type internal combustion engine. Fuel is pressurized by a fuel pump 5 and stored in a fuel delivery 8 at a high pressure. When the output shaft of the engine rotates and reaches a predetermined time or angle, fuel is injected from the injector 1 to the vicinity of the combustion chamber, and combustion is performed by discharging a high-voltage current generated in the ignition coil 4 by the ignition plug 7. . The fuel pressure is detected by the fuel pressure sensor 2, and the ECU 9 (engine control device) controls the fuel pump 5 so that the pressure becomes a target value. The ECU 9 includes a CPU that executes calculations by software, a ROM, a RAM, an I / O, a timer, an injector control device, and the like.
[0010]
FIG. 2 schematically shows an injector control unit of the ECU 9. The high-voltage upstream transistor 101 for controlling the energization of V_boost, the low-voltage upstream transistor 100 for controlling the energization of VB, and the downstream transistor 103 described in the preceding claims switch and connect an appropriate power supply to the injector 1 disposed therebetween. I do. Further, a current detection resistor 109 is disposed in the flow path of the injector current to detect the current flowing through the injector and control the current value at each time. This current detection method may be a Hall element, a current mirror circuit, or the like. In this embodiment, the two injectors share the upstream transistors 100 and 101 and are selectively energized by the downstream transistor 103. There is also a method in which the upstream is independent. In order to control these transistor groups, the embodiment includes an injector drive control circuit 104 that controls the energization of the electromagnetic coil based on an injector drive signal or the like issued from the PCU 105 that performs arithmetic control of the entire engine. This control circuit receives, for example, an injector operation signal 107 and a precharge signal 108 from the CPU 105, and switches the transistor group based on current values determined by internal or external current setting resistors 110, 111, 112, 113, for example. Drive. A part of the signal to be sent to the transistor, for example, the high-voltage upstream transistor drive signal 106 is connected to the CPU 105 in order to implement the method of the present invention. You can know when.
[0011]
FIG. 3 shows the relationship between the current value flowing through the electromagnetic coil of the injector controlled by the injector drive control circuit 104 and related signals. When the injector operation signal 107 is at a high level and the precharge signal is at a high level, precharge is started, and the current gradually increases as indicated by 205. When the precharge current reaches a predetermined value, the injector drive control circuit 104 keeps the precharge current 204 at a constant value. Thereafter, when the precharge signal 108 goes low and only the injector operation signal 107 goes high, the high voltage upstream transistor (101) in FIG. 2 is operated to start supplying a high voltage. The supply of V_boost causes the current in the electromagnetic coil to increase significantly, as shown at 203, and V_boost is supplied until the specified maximum current value 211 is reached. Thereafter, VB is supplied as shown, and the current decreases as indicated by 210 in accordance with the supply voltage difference. Thereafter, in order to forcibly reduce the current, for example, after the grounding operation 212 is performed, the holding current values 215 and 217 are separately controlled. The energization of the electromagnetic coil is basically shut off after transitioning to this state. Incidentally, the holding currents of 215 and 217 may be single.
[0012]
In order to move the plunger valve shutting off the fuel from the fuel shutoff position to the stable injection position as quickly as possible during the period of supplying V_boost of the above 203, in order to provide the maximum current that can be supplied in a short term. And has a close relationship with the operation of the injector plunger valve.
[0013]
Among the important fuel injection amount characteristics of the injector are the minimum injection amount and the maximum operating fuel pressure, the minimum injection amount, that is, the minimum injection amount that maintains the linearity of the injector opening time and the injection amount characteristic, is appropriate. Generally, a minimum electromagnetic coil energization period is set. That is, the plunger valve needs to reach the stable position at least a little, usually at the point where the supply of V_boost ends and the holding current 213 starts. That is, it means that the energizing time to the electromagnetic coil cannot be shorter than the start time of the holding current 213. Therefore, when the manufacturing variation of the injector 1, the wiring, and the ECU 9 is taken into consideration, it is assumed that there is a solid combination such as 202, in which the current rise of the electromagnetic coil is slow and the time until the transition to the holding current 213 is delayed. The minimum energization time had to be determined relatively large. For this reason, the minimum flow characteristic of the injector was apparently deteriorated due to this restriction.
[0014]
On the other hand, the maximum operating fuel pressure is the maximum pressure at which the plunger valve of the injector can be opened by the thrust of the electromagnetic coil. The pressure here is the differential pressure between the upstream and downstream of the plunger valve. This characteristic changes with the current integral value during the period 200 during which V_boost is supplied, that is, the current waveform area at the time of V_boost supply in terms of the injector current waveform. Generally, the larger this value is, the better the maximum operating fuel pressure characteristic is. From this, when the current of the electromagnetic coil rises quickly as in 201, the above-described current integrated value decreases, and the maximum operating fuel pressure characteristic deteriorates.
[0015]
In order to solve the above problem, the present invention operates the precharge operation, accurately controls the time T_peak 200 from when V_boost is supplied to when the maximum current value 211 is reached, and considers the variation 209. To reduce the variation of this characteristic by securing the sufficient current integration value during V_boost supply by improving the minimum energizing time of the electromagnetic coil, and consequently improving the minimum fuel injection amount characteristic, and also ensuring the maximum operating fuel pressure characteristic. Performance can be improved. If the injectors have the same performance, the tolerances of the electromagnetic coil, wiring electric resistance, injector control circuit, and the like can be increased, and these can be manufactured at low cost.
[0016]
FIG. 4 illustrates a method of operating T_peak by precharging based on two types of embodiments. These are the same in changing T_peak 408. The first embodiment A is a method of changing the magnitude C_pre 409 of the precharge current. Since the relationship between T_peak 408 and precharge current C_pre 409 is as indicated by 403, if the injector drive control circuit (104) of FIG. 2 is provided with a means for varying the precharge current stepwise or continuously, the T_peak becomes the reference value. When T_peak is smaller than 410, T_peak is increased by decreasing the precharge current C_pre 409 as indicated by 402. Conversely, when T_peak is larger than the reference value 410, T_peak is increased by increasing the precharge current C_pre 409 as indicated by 400. So-called feedback control (hereinafter referred to as feedback control) can be realized, and the energization control of the electromagnetic coil such that the actual T_peak 408 is always close to the reference value 410 can be performed.
[0017]
Another embodiment B is a simpler method, and the circuit shown in FIG. 2 is suitable for this embodiment. In this method, a means for changing the control current value C_pre 409 of the precharge is fixed without being provided, and the same effect as that of making the precharge current variable is obtained by making the precharge energizing time T_pre405 variable. is there. Since the relationship between T_peak 408 and precharge time T_pre 405 is as indicated by 407, if the precharge control current is fixed and increased or no current control is performed, the precharge current gradually increases due to the influence of the inductance of the electromagnetic coil. Utilizing this, the precharge current at the start of V_boost supply can be varied by changing the precharge time T_pre405. This method does not require a resistance value switching means for specifying a variable current for the injector drive control circuit, a signal line for indicating the current value, and a circuit therefor, so that the ECU can be manufactured at low cost.
[0018]
Although any of the above methods can be realized by using an electric circuit, it is more reasonable to realize the method by software processing of a CPU built in the ECU 9.
[0019]
FIG. 5 shows an embodiment of the present invention in which the method of FIG. 4B is realized by software processing. Normally, the ECU 9 executes the engine control software processing in a time-division manner, and executes an interrupt processing for processing that must be executed asynchronously at that time. In general, the control of the injector is generally automatically started as an interruption process when a predetermined fuel injection start timing comes. Reference numeral 500 denotes a base point of an interrupt process for performing a fuel injection process on software, and this time is a time to start energizing the injector. Generally, this interrupt processing is started when a predetermined time has elapsed from the rotation angle of the engine output shaft or a predetermined rotation angle. Reference numeral 501 denotes a fuel injection process in which various calculations are performed. In the fuel injection process, a process described between 503 and 512 is a part to be particularly added in the present invention. In the process 504, the precharge is controlled to be energized for the period of T_pre updated at the time of the previous fuel injection process, and when the time T_pre elapses, the application of V_boost is started in the process 505. In processes 506 and 507, V_boost monitors whether or not the injector drive control circuit (104) in FIG. 2 has cut off V_boost, and measures the time from the application of V_boost to the cutoff. This means measuring T_peak (200) in FIG. When the application of V_boost is completed, the actual T_peak in the current injection is determined in process 508. This T_peak determination process may be automatically performed using, for example, a function of a timer circuit. The target T_peak determined in advance in the process 509 or separately calculated is compared with the actual T_peak, and if there is no difference or does not exceed a predetermined width, the T_pre is updated without updating the T_pre. In process 512, T_pre for the next injection is determined. If the actual T_peak is larger than the target T_peak in the judgment 509, T_pre is increased by a predetermined amount and an upper limit in a process 511, and a T_pre for the next injection is determined in a process 512. If the actual T_peak is smaller than the target T_peak in the judgment 509, the T_pre is decreased by a predetermined amount and the lower limit as a limit, and in the process 512, the T_pre for the next injection is determined. Processes 505 to 512 are T_peak feedback processes, and this portion may be processed as a function calculation. These processes may be performed inside the injector drive control circuit 104 instead of the CPU 105. Further, when the electromagnetic coil and other physical characteristics change due to deterioration or the like, the above T_peak changes. Therefore, it is possible to detect a defect by referring to the T_peak. Further, if the precharge time T_pre is recorded in the CPU even after the main power supply is cut off, it is possible to control the power supply so that an appropriate T_peak is obtained from the first fuel injection after the power supply is supplied.
[0020]
The present invention actively stabilizes the time from supply of a first power supply voltage (hereinafter, V_boost) to switching to a second power supply voltage (hereinafter, VB) by controlling the above-described pre-current (hereinafter, precharge). It is.
[0021]
ADVANTAGE OF THE INVENTION According to this invention, the electrical required tolerance of an electromagnetic coil or a power supply and a control circuit can be expanded, and also an injector, wiring, and a control circuit can be inexpensive.
[0022]
【The invention's effect】
According to the present invention, the fuel flow rate, the maximum operating fuel pressure, and other characteristics of the injector can be improved without reducing the tolerance of the injector and its drive circuit. In addition, if the characteristics are the same, the tolerance can be increased, so that an inexpensive injector and its driving circuit can be manufactured.
[Brief description of the drawings]
FIG. 1 is a drawing showing an example of an organization to which the present invention can be applied.
FIG. 2 is an example of an injector drive control circuit configuration.
FIG. 3 is a relationship diagram between a current waveform of an injector electromagnetic coil and a control signal.
FIG. 4 is a diagram showing a relationship between precharge and T_peak.
FIG. 5 is a flowchart when the present invention is performed by software.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Injector, 5 ... Fuel pump, 9 ... ECU (engine control unit), 100 ... Low-voltage side upstream transistor, 101 ... High-voltage upstream transistor, 103 ... Downstream side transistor, 104 ... Injector drive control circuit, 105 ... CPU (Central Processing Unit), 200: V_boost supply period (T_peak), 204: precharge current (C_pre), 209: variation of T_peak, 211: maximum current value (C1), 213: first holding current (C2) , 216: second holding current (C3), 403: characteristics of precharge current C_pre and T_peak, 407: characteristics of precharge time T_pre and T_peak, 500 to 502: interruption of fuel injection, 503 to 512: T_pre Update processing flow.

Claims (9)

Apparatus for opening and closing an electromagnetic valve with a drive circuit from a power supply, having at least two power supply voltages, means for detecting current flowing through the electromagnetic valve, and an electromagnetic valve for switching from a first power supply voltage to a second power supply voltage A current switching threshold, a means for comparing the current detection value detected by the detection means with the current switching threshold, and starting driving with the first power supply voltage, wherein the solenoid valve current is lower than the current threshold. Power supply voltage switching means for switching to the second power supply voltage after the increase, after switching to the second power supply voltage, holding current control means for opening and holding the solenoid valve, after starting to apply the first power supply voltage A first power supply time detecting means for detecting a time until it ends or a predetermined time until the first holding current is started, and a first power supply for supplying a current of a magnitude that the solenoid valve does not completely respond to yet. Give voltage And a first power supply time comparing means for comparing the first power supply time with a reference value of the first power supply time, and adjusting the precurrent supply time based on the comparison result. A drive device for an electromagnetic valve for an internal combustion engine, comprising a pre-current adjusting means. 2. The solenoid valve driving device according to claim 1, wherein the precurrent adjustment is performed based on the precurrent supply time or the current value. 2. The driving apparatus for an electromagnetic valve for an internal combustion engine according to claim 1, wherein the first power supply time comparison means adjusts the magnitude of the first power supply voltage based on a result of the comparison. Means for forcibly reducing the solenoid valve current during the period from the first power supply stop to the second power supply start, the first power supply time comparing means, and 2. The driving apparatus for an electromagnetic valve for an internal combustion engine according to claim 1, wherein a forced current reduction period of the electromagnetic valve current to be reduced is adjusted. In the case of controlling to two or more current values during the supply of the second power supply voltage, the point of switching from one current to the other is switched based on the first power supply time comparison means and the comparison result. The drive device for an electromagnetic valve for an internal combustion engine according to claim 1. 2. The electromagnetic valve for an internal combustion engine according to claim 1, wherein the solenoid valve is a fluid control solenoid valve, and the first power supply time comparison unit and the pressure of the fluid are adjusted based on the comparison result. . 2. The solenoid valve driving device for an internal combustion engine according to claim 1, wherein the magnitude of the first power supply voltage is adjusted by a first power supply time comparison unit and the magnitude of the voltage based on the comparison result. . The abnormality of the solenoid valve is detected as the abnormality of the solenoid valve when the first power supply time comparison means and the result of the comparison result are larger or smaller than a predetermined difference. 2. The driving device for an electromagnetic valve for an internal combustion engine according to claim 1. The storage device has a storage unit that retains a value even when the main power supply of the control device is shut off, and the storage unit has a difference between the first power supply time and the reference value, or an instantaneous or average first power supply time, The driving device for an electromagnetic valve for an internal combustion engine according to claim 1, which stores:

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