JP5558135B2 - Drive control method for pressure control valve in common rail fuel injection control device and common rail fuel injection control device - Google Patents

Description

  The present invention relates to a driving method of an electromagnetic pressure control valve in a common rail fuel injection control device, and in particular, to ensure consistency between the electrical characteristics of the electromagnetic pressure control valve alone and the required performance in the common rail fuel injection control device. Etc.

   As a fuel injection control device for an internal combustion engine such as a diesel engine, a fuel is pressurized by a high-pressure pump, is pumped to a common rail that is an accumulator, is accumulated, and the accumulated high-pressure fuel is supplied to the injector. Common rail fuel injection control devices that enable high-pressure fuel injection to engines are known for their excellent fuel efficiency and emission characteristics. Various improvements to operating characteristics have been proposed and put to practical use. ing.

  As a method for controlling the fuel pressure of the common rail in such a common rail fuel injection control device, a high pressure fuel is pumped to the common rail so that the fuel pressure of the common rail becomes a target common rail pressure set according to the operating state of the engine. Generally, a method of controlling energization to a metering valve for metering the discharge amount of the pump device and an electromagnetic pressure control valve for reducing the fuel pressure of the common rail by an electronic control unit is often used.

  By the way, the operation characteristics of the electromagnetic control valve are generally configured so that the state of the on-off valve can be continuously controlled from zero energization current depending on the structure of the magnetic circuit and the difference in magnetic characteristics, etc. However, the electromagnetic pressure control valve in the above-described common rail fuel injection control device is continuously controlled from zero energization current from the viewpoint of freedom of control. It is desirable to use a configuration that can be used.

On the other hand, in a motor vehicle equipped with a common rail fuel injection control device, various failure diagnosis is generally performed for various devices including the common rail fuel injection control device.
For example, as a solenoid valve failure diagnosis method as described above, in a so-called PWM driven solenoid valve, there is a method for determining whether or not a failure has occurred depending on whether or not a voltage generated in the solenoid valve by energization satisfies a predetermined value. Various proposals and practical applications have been made (see, for example, Patent Document 1).

JP 2007-242332 A (page 3-6, FIG. 1 to FIG. 2)

By the way, the electromagnetic pressure control valve of the above-described common rail fuel injection control device is also usually subject to failure diagnosis. However, for failure diagnosis, the solenoid valve needs to be in the minimum energized state. Is done.
For this reason, even if the pressure control valve itself has a configuration that can be driven from zero energization current, the energization range of the electromagnetic pressure control valve in rail pressure control is the minimum current required for failure diagnosis or its vicinity. Therefore, there is a problem that it is impossible to cope with the case where rail pressure control at zero energization current is required, and rail pressure control that makes full use of the original operating characteristics of the electromagnetic pressure control valve is not possible. .
A similar problem is not only for the pressure control valve of the common rail fuel injection control device, but it is desirable that the current flow is zero, that is, the duty of the PWM signal is zero. The failure diagnosis timing also occurs in various types of electronic devices and electronic devices that are PWM-controlled and used in electronic devices that require a predetermined small current flow.

The present invention has been made in view of the above circumstances, and a common rail fuel injection control device capable of satisfying operation requirements in various operations of the device as much as possible while fully utilizing the original operation characteristics of the electromagnetic pressure control valve. And a common rail type fuel injection control device.
Another object of the present invention is that a state in which the energization current is zero is desired. On the other hand, for failure diagnosis of the electromagnetic actuator, a predetermined small current energization state is required at the timing of failure diagnosis. Provided is a drive control method suitable for PWM-controlled electromagnetic actuators used in various electronic devices and electronic devices.

In order to achieve the above object of the present invention, a drive control method for a pressure control valve of a common rail fuel injection control device according to the present invention includes:
A high-pressure pump device that pumps fuel to the common rail, a pressure control valve provided in a return passage of fuel from the common rail, and an electronic control unit that controls driving of the high-pressure pump device and the pressure control valve,
The electronic control unit conducts energization of the pressure control valve by feedback control by PWM control, and is configured to be controllable so as to be a target rail pressure calculated based on engine operation information. A drive control method of the pressure control valve in an apparatus,
When the target duty for PWM control of the pressure control valve calculated and calculated by the electronic control unit is not more than a predetermined minimum value, the energization current of the pressure control valve is set to zero, and the pressure control When the driving state of the valve energizing current zero is continued beyond a predetermined specified time, the energizing current of the pressure control valve is set as a predetermined diagnostic current required for failure diagnosis processing. The fault diagnosis process is configured to be executable.
In order to achieve the above object of the present invention, a common rail fuel injection control device according to the present invention includes:
A high-pressure pump device that pumps fuel to the common rail, a pressure control valve provided in a return passage of fuel from the common rail, and an electronic control unit that controls driving of the high-pressure pump device and the pressure control valve,
The electronic control unit conducts energization of the pressure control valve by feedback control by PWM control, and is configured to be controllable so as to be a target rail pressure calculated based on engine operation information. A device,
The electronic control unit calculates a target duty for PWM control of the pressure control valve, and when the calculated target duty is equal to or less than a predetermined minimum value, an electric current of the pressure control valve is calculated. When it is determined that the driving state of zero current supply current of the pressure control valve is in a state of continuing beyond a predetermined specified time, the current supply current of the pressure control valve is used for failure diagnosis processing. A failure diagnosis process can be executed as a predetermined diagnostic current required.

  According to the present invention, when there is a need to reduce the current flowing through the pressure control valve while the pressure control valve failure diagnosis process is not being performed, the current flowing is set to zero and the failure diagnosis process is performed. When the operation is performed, the energization current of the pressure control valve is returned to the predetermined current value necessary for failure diagnosis. The effect is that the requirement can be satisfied as much as possible.

It is a block diagram which shows one structural example of the common rail type | mold fuel-injection control apparatus in embodiment of this invention. It is a longitudinal cross-sectional view which shows schematic structure of the pressure control valve of the electromagnetic control type used for the common rail type fuel injection control apparatus shown by FIG. 4 is a subroutine flowchart showing a procedure of a pressure control valve drive control process executed by an electronic control unit constituting the common rail fuel injection control device shown in FIG. 1. FIG. 2 is a schematic characteristic diagram showing an example of a schematic change characteristic between an energization current and a rail pressure of an electromagnetic control type pressure control valve used in the common rail type fuel injection control device shown in FIG. 1.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4.
The members and arrangements described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.
First, a configuration example of an internal combustion engine injection control apparatus to which a pressure control valve drive control method according to an embodiment of the present invention is applied will be described with reference to FIG.
Specifically, the internal combustion engine injection control device shown in FIG. 1 is particularly configured as a common rail fuel injection control device.

The common rail fuel injection control device includes a high pressure pump device 50 that pumps high pressure fuel, a common rail 1 that stores the high pressure fuel pumped by the high pressure pump device 50, and a high pressure fuel supplied from the common rail 1 as a diesel engine. A plurality of fuel injection valves (injectors) 2-1 to 2-n (hereinafter referred to as “engines”) for injection and supply to three cylinders, fuel injection control processing, metering valve drive control processing described later, and the like are executed. The electronic control unit (noted as “ECU” in FIG. 1) 4 is configured as a main component.
Such a configuration itself is the same as the basic configuration of this type of fuel injection control apparatus that has been well known.

The high-pressure pump device 50 has a known and well-known configuration that is mainly configured by a feed pump 5, a metering valve 6, and a high-pressure pump 7 as a fuel supply pump.
In such a configuration, the fuel in the fuel tank 9 is pumped up by the feed pump 5 and supplied to the high-pressure pump 7 through the metering valve 6. As the metering valve 6, an electromagnetic proportional control valve is used, and the amount of energization is controlled by the electronic control unit 4, so that the flow rate of fuel supplied to the high-pressure pump 7, in other words, the discharge of the high-pressure pump 7. The amount is to be adjusted.

A return valve 8 is provided between the output side of the feed pump 5 and the fuel tank 9 so that excess fuel on the output side of the feed pump 5 can be returned to the fuel tank 9. .
The feed pump 5 may be provided separately from the high-pressure pump device 50 on the upstream side of the high-pressure pump device 50, or may be provided in the fuel tank 9.

  The fuel injection valves (injectors) 2-1 to 2-n are provided for each cylinder of the diesel engine 3, respectively, and are supplied with high-pressure fuel from the common rail 1 and perform fuel injection by injection control by the electronic control unit 4. It is like that.

  In the common rail 1 of the present invention, a return passage (not shown) for returning surplus high-pressure fuel to the tank 9 is provided with an electromagnetically controlled pressure control valve (hereinafter referred to as “PCV” as necessary for convenience of explanation). Is provided together with the metering valve 6 to control the rail pressure.

The electronic control unit 4 has, for example, a microcomputer (not shown) having a known and well-known configuration, a storage element (not shown) such as a RAM and a ROM, and a fuel injection valve 2- A drive circuit (not shown) for driving 1 to 2-n and an energization circuit (not shown) for energizing the metering valve 6 and the pressure control valve 12 are configured as main components. It has become a thing.
In addition to the detection signal of the pressure sensor 11 that detects the pressure of the common rail 1 being input to the electronic control unit 4, various detection signals such as the engine speed and the accelerator opening are used to control the operation of the engine 3 and fuel injection. It is input to be used for control.

  There are a plurality of methods for rail pressure control by changing the operation states of the metering valve 6 and the pressure control valve 12 by the electronic control unit 4, but in the embodiment of the present invention, there are several methods. Is based on the premise that a PCV control mode in which rail pressure control is performed at least by driving control of the pressure control valve 12 is executed.

  That is, the PCV control mode is a rail pressure control state in which a desired rail pressure is obtained by adjusting the valve opening degree of the pressure control valve 12 while the metering valve 6 is fully opened, and the pressure control valve 12 is driven. The control is performed by so-called feedback control using so-called PWM (Pulse width Modulation) control.

Here, a schematic configuration of the pressure control valve 12 in the embodiment of the present invention will be described with reference to FIG.
The pressure control valve 12 is configured with a valve body 21, a valve needle 22, an electromagnetic coil 23, and a pressing spring 24 as main components, and such a configuration itself is well known in the art. .
A needle hole 25 in which the valve needle 22 is slidably housed in the longitudinal axis direction is formed in the valve body 21, and the rear end side of the valve needle 22 is formed on the rear end side of the valve needle 22. An armature storage section 27 in which a disk-shaped armature 26 to be attached is disposed is formed to communicate with each other. Further, at the center of the armature storage section 27, the armature 26 is sandwiched between the valve needle 22 and the opposite side. In this position, a spring accommodating portion 28 in which the pressing spring 24 is accommodated is recessed.

In the needle hole 25, a seat portion 29 is formed in which the tip end portion of the valve needle 22 is seated and separated, and one end side of the rail communication path 30 formed in the valve body 21 is at the center of the seat portion 29. The other end of the rail communication passage 30 is open to the outer surface of the valve body 21 and is connected to the common rail 1 although not shown.
Further, a return fuel communication passage 31 communicating with the needle hole 25 is formed in the valve body 21 at a portion relatively close to the tip end side of the valve needle 22, and the return fuel communication passage 31 of the valve body 21 of the return fuel communication passage 31 is formed. The end that opens on the outer surface is connected to the return fuel passage (not shown).

Further, an electromagnetic coil 23 is disposed in the valve body 21 in the vicinity of the armature storage portion 27 so as to surround the needle hole 25 in an annular shape, and the energization thereof can be controlled by the electronic control unit 4.
In such a configuration, the valve needle 22 of the pressure control valve 12 is tapered by the pressing spring 24 housed in the spring housing portion 28 so as to relatively gently press the armature 26 in a state where the electromagnetic coil 23 is not energized. The tip formed in the shape is seated on the seat portion 29 relatively gently.

In this state, when the fuel pressure of the common rail 1 becomes a certain level or higher, the tip of the valve needle 22 is separated from the seat portion 29 by the fuel pressure, and the fuel in the common rail 1 passes through the needle hole 25. It flows from the rail communication path 30 to the return fuel communication path 31 and is returned to the return fuel path (not shown).
On the other hand, when the electromagnetic coil 23 is energized, the valve needle 22 is pressed toward the seat portion 29 with a force corresponding to the energization amount, and the pressure control valve 12 is closed.

Next, the pressure control valve drive control process executed by the electronic control unit 4 will be described with reference to FIGS. 3 and 4.
First, when the electronic control unit 4 executes the drive control processing of the pressure control valve in the embodiment of the present invention, it is assumed that the vehicle is an automatic vehicle as described below.
That is, first, the energization characteristic of the pressure control valve 12 itself can continuously vary the energization current from zero, and the pressing force against the seat portion 29 of the valve needle 22 increases as the current increases. It has become. In other words, the tip of the valve needle 22 cannot be separated from the seat portion 29 unless the fuel pressure in the common rail 1 is increased.
Therefore, for example, if there is no restriction on the current flowing through the pressure control valve 12 by the failure diagnosis process described below, the control characteristics of the rail pressure with respect to the current flowing through the pressure control valve 12 are schematically shown in FIG. As shown in the characteristic, the rail pressure can be continuously increased as the conduction current increases from zero.

However, in the failure diagnosis processing for various vehicle operations performed in the electronic control unit 4, failure diagnosis of the pressure control valve 12 is one item, and the failure diagnosis is executed (for example, whether there is a disconnection or the like). In this case, the pressure control valve 12 is required to be energized with a very small predetermined diagnostic current Iins (see FIG. 4).
For this reason, in the conventional apparatus, a predetermined diagnostic current Iins or a current in the vicinity thereof is set as the minimum value of the energization current of the pressure control valve 12, and the range of the rail pressure control is determined in a range exceeding this, Rail pressure control was performed.

Therefore, in the conventional apparatus, although the pressure control valve 12 can control the operation even when the pressure is less than the predetermined diagnostic current Iins, this range is excluded from rail pressure control.
However, in a certain operation state of the vehicle, the rail pressure when the energization current of the pressure control valve 12 is zero may be required.
The drive control process of the pressure control valve in the embodiment of the present invention enables the rail pressure control when the energization current of the pressure control valve 12 is zero as described above without affecting the failure diagnosis process. Is.

  Further, the energization control of the pressure control valve 12 is performed by so-called PWM control as in the conventional device. That is, the energization control is performed by changing the average current value of the current flowing through the pressure control valve 12 by changing the duty of the pulse voltage signal applied to the pressure control valve 12.

Under such a premise, when the pressure control valve drive control processing by the electronic control unit 4 is started, it is first determined whether or not the target PCV drive duty falls below the duty-off threshold (FIG. 3). Step S102).
Here, when the rail pressure control is performed in the PCV control mode described above by the rail pressure control process executed by the electronic control unit 4, the target PCV drive duty is the operation of the engine 3 by the pressure control process. This is a target duty of a pulse voltage signal that is a PWM signal applied to the pressure control valve 12 that is calculated by a predetermined calculation formula based on the state or the like.

Further, the duty-off threshold is the minimum value of the duty of the pulse voltage signal applied to the pressure control valve 12. This minimum value is a value other than zero, and a specific value is appropriately set individually based on the scale of the common rail fuel injection control device, the range of rail pressure control, and the like. In the embodiment of the present invention, the duty-off threshold value is set to the predetermined diagnostic current Iins.
Since the target PCV drive duty is calculated and calculated in other processing executed by the electronic control unit 4 as described above, the calculated value may be used, and is calculated again in step S102. It is not necessary.
Further, since the duty-off threshold is predetermined, the value is stored in an appropriate storage area of the electronic control unit 4 and is read and used when executing step S102. You can do it.

  Therefore, if it is determined in step S102 that the target PCV drive duty <duty-off threshold is satisfied (in the case of YES), the pressure control valve 12 is turned on based on the operating state of the engine 3 and the like. On the other hand, the process proceeds to the process of step S104, which will be described below, assuming that a request for zero is made. On the other hand, if it is determined that the target PCV drive duty <duty-off threshold is not satisfied (NO), Assuming that the process is not suitable for executing the process, the series of processes is terminated, and the process returns to the main routine (not shown).

In step S104, the PCV drive duty is set to 0% by the electronic control unit 4, and at the same time, feedback control of the pressure control valve 12 is stopped (see step S106 in FIG. 3), and the pressure control valve 12 is energized. The current will be zero.
Next, it is determined whether or not the driving state of the pressure control valve 12 has been continued for a specified time or longer (see step S108 in FIG. 3).

And when it determines with continuing for more than regulation time (in the case of YES), it progresses to the process of step S110 mentioned below, On the other hand, when it determines with not continuing more than regulation time (in the case of NO) In this case, the series of processes is terminated, and the process returns to the main routine (not shown).
Whether or not the state in which the energization current of the pressure control valve 12 is zero is continued for a specified time or more in step S108 is determined based on the failure diagnosis process. It is for determining whether or not the duration has been continued for a time to affect
Therefore, the specified time is preferably set with reference to a cycle in which the failure diagnosis of the pressure control valve 12 is repeated.

  In step S110, the electronic control unit 4 outputs the disconnection detection duty to a drive circuit of the pressure control valve 12 (not shown), and the pressure control valve 12 is driven and controlled by the duty. Here, the disconnection detection duty is a duty required to obtain a predetermined diagnostic current Iins (see FIG. 4).

Next, in the electronic control unit 4, it is determined whether or not a disconnection failure of the pressure control valve 12 is detected in a failure diagnosis process that is executed separately (see step S <b> 112 in FIG. 3).
When it is determined in the failure diagnosis processing that a disconnection failure of the pressure control valve 12 has been detected (in the case of YES), the disconnection failure processing in the failure diagnosis processing is executed (see step S114 in FIG. 3). This process is terminated. Note that the disconnection failure processing in the failure diagnosis processing is, for example, generation of an alarm, and the content thereof is not limited to a specific one and should be arbitrarily set.

On the other hand, if it is determined in step S112 that a disconnection failure of the pressure control valve 12 has not been detected (in the case of NO), the failure diagnosis process is normally executed, and at least the pressure control valve 12 has also failed. The drive control of the pressure control valve 12 is returned to the drive state before entering the failure diagnosis (see S104 and S106 in FIG. 3), that is, the state where the energization current is zero, in other words, the energization stop state. (Refer to step 116 in FIG. 3), a series of processing ends.
In the above-described embodiment of the present invention, the rail pressure control characteristic with respect to the energizing current of the pressure control valve 12 is such that the rail pressure increases as the energizing current increases as shown in FIG. Although described, it is not necessary to be limited to such a characteristic, and conversely, a so-called reverse characteristic in which the rail pressure decreases as the energization current increases may be used.

In the above-described embodiment of the present invention, the drive control control method for the pressure control valve 12 of the common rail fuel injection control device has been described. However, the present invention is not necessarily limited to the pressure control valve 12.
That is, the above-described drive control method of the pressure control valve 12 in the embodiment of the present invention is a PWM-controlled electromagnetic actuator used in various electronic apparatuses and devices, and one of the drive states thereof is an energization current. Is set to zero, that is, the duty of the PWM signal is set to zero. On the other hand, as described in the embodiment of the present invention, in order to diagnose the failure of the electromagnetic actuator, at the timing of the failure diagnosis, a predetermined value is used. The present invention is basically applicable to electromagnetic actuators that require a small current flow state. In addition, as an electromagnetic actuator, a linear motor, an electric motor, etc. may be sufficient besides the control valve like embodiment of this invention.

The common rail type fuel injection for which further improvement of controllability is desired because the request for driving the pressure control valve 12 in the rail pressure control and the request for driving the pressure control valve 12 in the failure diagnosis process are compatible. Suitable for control device.
Further, while a state with a duty of zero is desired, for various types of electronic devices and electronic devices that require a predetermined small current energization state at the time of failure diagnosis for failure diagnosis of electromagnetic actuators. Also suitable for PWM controlled electromagnetic actuators used.

DESCRIPTION OF SYMBOLS 1 ... Common rail 2-1-2-n ... Fuel injection valve 3 ... Diesel engine 4 ... Electronic control unit 11 ... Pressure sensor 12 ... Pressure control valve 50 ... High-pressure pump apparatus

Claims (6)

A high-pressure pump device that pumps fuel to the common rail, a pressure control valve provided in a return passage of fuel from the common rail, and an electronic control unit that controls driving of the high-pressure pump device and the pressure control valve,
The electronic control unit conducts energization of the pressure control valve by feedback control by PWM control, and is configured to be controllable so as to be a target rail pressure calculated based on engine operation information. A drive control method of the pressure control valve in an apparatus,
When the target duty for PWM control of the pressure control valve calculated and calculated by the electronic control unit is not more than a predetermined minimum value, the energization current of the pressure control valve is set to zero, and the pressure control When the driving state of the valve energizing current zero is continued beyond a predetermined specified time, the energizing current of the pressure control valve is set as a predetermined diagnostic current required for failure diagnosis processing. A drive control method for a pressure control valve in a common rail fuel injection control device, wherein a failure diagnosis process can be executed. The predetermined specified time, the drive control method of the pressure control valve in the common rail fuel injection control device according to claim 1, wherein the equivalent to the repetition period of the failure diagnosis process. 3. The common rail fuel injection control apparatus according to claim 2 , wherein when the failure of the pressure control valve is not detected by executing the failure diagnosis process, the drive control of the pressure control valve is returned to a normal state. Drive control method for pressure control valve. A high-pressure pump device that pumps fuel to the common rail, a pressure control valve provided in a return passage of fuel from the common rail, and an electronic control unit that controls driving of the high-pressure pump device and the pressure control valve,
The electronic control unit conducts energization of the pressure control valve by feedback control by PWM control, and is configured to be controllable so as to be a target rail pressure calculated based on engine operation information. A device,
The electronic control unit calculates a target duty for PWM control of the pressure control valve, and when the calculated target duty is equal to or less than a predetermined minimum value, an electric current of the pressure control valve is calculated. When it is determined that the driving state of zero current supply current of the pressure control valve is in a state of continuing beyond a predetermined specified time, the current supply current of the pressure control valve is used for failure diagnosis processing. A common rail fuel injection control device configured to be able to execute a failure diagnosis process as a predetermined diagnostic current required. 5. The common rail fuel injection control device according to claim 4 , wherein the predetermined specified time is equal to a repetition period of the failure diagnosis process. The electronic control unit is configured to return the drive control of the pressure control valve to a normal state when a failure of the pressure control valve is not detected by execution of the failure diagnosis process. 5 common rail fuel injection control apparatus according.

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