JP2008208772A - Fuel injection device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection device for an engine capable of more accurate fuel injection control. <P>SOLUTION: When control process of a controller 18 shifts to idling control routine, each operation information is read respectively and it is judged whether the engine 1 is under an idling state or not (step s1, s2). If it is judged as idling after warming up, drive width pulse Ta#1-Ta#4 of each cylinder is measured and stored in injection quantity operation process (step s12) after execution of idling speed control (step s7). After that, learning result of drive pulse width Ta#1-Ta#4 for each cylinder is correlated to learning auxiliary injection quantity map and is reflected to fuel injection drive control executed in main routine of the fuel injection device A after that to control injection of each fuel injection valve 2 (step s18). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an engine fuel injection device capable of performing the injection amount control of a fuel injection device with higher accuracy.

  In a direct injection engine, for example, a common rail diesel engine, fuel is increased in pressure by a fuel injection pump, the high pressure fuel is sent to a common rail, and the common rail guides the fuel injection valve provided in each cylinder. Each fuel injection valve includes an electromagnetic injection control valve (needle valve), and the injection control valve is controlled to open and close according to the fuel injection amount, the injection timing, and the number of injections.

  By the way, in order to further improve the exhaust gas performance of the engine or to further suppress the noise generated when the engine is driven, the injection amount is set so that the fuel amount injected from the fuel injection device becomes a target value as intended. It is important to increase accuracy. In particular, the precision of injection quantity is improved by more accurately controlling small injection quantities such as pre-injection and pilot injection, which are performed prior to main injection in normal injection, or after injection and post-injection after main injection. This is very important.

Here, taking the pilot injection as an example, the relationship between the injection amount and the generation of smoke and noise will be described.
FIG. 10 is a graph showing an example of the degree of smoke and noise generation with respect to the pilot injection amount. In this graph, the upper curve shows the noise generation characteristic with respect to the pilot injection amount, and the lower curve shows the smoke generation characteristic with respect to the pilot injection amount.
As shown in FIG. 10, when the pilot injection amount is large, both noise and smoke tend to be deteriorated. Conversely, when the amount is too small, noise tends to be extremely deteriorated. For this reason, in order to suppress smoke and noise, it is necessary to perform injection amount control of sub-injection such as pilot injection and post injection more accurately.

However, sub-injection such as pilot injection and post-injection has a smaller injection amount than main injection, and is easily affected by individual differences in fuel injection valves (injectors), deterioration over time, and the like. Therefore, the fuel injection amount in the normal injection has been corrected conventionally.
For example, in Japanese Patent Application Laid-Open No. 2004-183657 (Patent Document 1), the drive time of the injector is increased or decreased to cause the internal combustion engine to generate a constant rotational speed, and the drive time at which the constant rotational speed is generated is minimized. A control method for a fuel metering system that stores the drive time is disclosed.

JP 2004-183657 A

By the way, it is required to stabilize the fuel injection by adjusting the fuel injection amount more accurately.
The present invention has been made paying attention to the above-described problems, and an object of the present invention is to provide an engine fuel injection device capable of performing injection amount control with higher accuracy.

  In order to achieve the above-mentioned object, the invention of claim 1 is directed to a fuel injection valve provided in a cylinder of an engine and a rotation of the engine by controlling a fuel injection amount when the engine is in a predetermined operating range. The first feedback control means for feedback-controlling the number to a predetermined target rotational speed and storing the control result of the fuel injection amount as a basic fuel injection amount; and when in the predetermined operating range, by the first feedback control means The fuel of the basic fuel injection amount is injected at a retarded injection timing delayed from the injection timing of fuel injection at the time of control, and the basic fuel injection amount at an injection timing advanced from the retarded injection timing. Separately, preliminary fuel injection is performed, and the injection amount of the preliminary fuel injection is controlled to feedback control the engine speed to the predetermined target engine speed. A second feedback control means for storing the control result of the quantity as a corrected fuel injection quantity; and a correcting means for correcting a control command for the fuel injection valve at a normal time based on the corrected fuel injection quantity. And

  According to a second aspect of the present invention, in the fuel injection device for an engine according to the first aspect, the engine is a multi-cylinder engine having a plurality of cylinders, and the fuel injection valve is provided in each of the plurality of cylinders. The correction means corrects a control command for each of the fuel injection valves for each of the plurality of cylinders.

  According to a third aspect of the present invention, in the fuel injection device for an engine according to the first or second aspect, the predetermined operating range is an idle operating range.

  According to the first aspect of the present invention, the control result of the fuel injection amount when the engine is subjected to the first feedback control to the predetermined target rotational speed is set as the basic fuel injection amount, and the engine is further subjected to the second feedback control to the target rotational speed, Control the injection amount of the preliminary fuel injection by retarding the basic fuel injection amount and performing the preliminary fuel injection at an advanced injection timing separately from the basic fuel injection amount. The result is stored as a corrected fuel injection amount, and the control command for the normal fuel injection valve is corrected based on the corrected fuel injection amount, so that the accuracy of the injection control amount can be made more accurate. Thereby, since the injection control amount can be stabilized, the generation of noise and smoke can be suppressed.

  According to the second aspect of the invention, since the injection control amount of the fuel injection valve for each cylinder is corrected based on the corrected fuel injection amount, the accuracy of the injection control amount for each cylinder is made more accurate even in a multi-cylinder engine. And generation of noise and smoke can be suppressed.

  According to the third aspect of the present invention, the accuracy of the injection control amount can be made more accurate by correcting the control command in an idle operation region where the engine rotation is relatively stable.

FIG. 1 schematically shows a common rail diesel engine (hereinafter simply referred to as engine 1) provided with an engine fuel injection device A as an embodiment of the present invention.
The engine 1 is a multi-cylinder direct injection type (in this embodiment, an example of four cylinders is described, and only one cylinder among the four cylinders is shown in FIG. 1), and a cylinder equipped with a fuel injection valve 2 for each cylinder. A combustion chamber 7 is formed by the head 3, the cylinder block 4, and the cavity 6 of the piston 5. The engine 1 is provided with an intake passage 8 and an exhaust passage 9 communicating with each cylinder. The intake passage 8 is provided with a compressor 12 (back side in FIG. 1) of the supercharger 11, and the exhaust passage 9 is provided with a turbine 13 of the supercharger 11.

  The supercharger 11 of this embodiment is a variable capacity turbo (VGT). The supercharger 11 uses the energy of the exhaust gas to rotate the turbine 13 and rotates the compressor 12 located on the same axis to boost the intake air. When the intake air is pressurized, high-density air is sent into the combustion chamber 7 and the fuel injected through the fuel injection valve 2 is mixed and burned, and the output of the engine 1 is increased.

  An air cleaner 14 is disposed upstream of the compressor 12 in the intake passage 8, and an air flow sensor 15 serving as intake air amount detection means is disposed in the casing of the air cleaner 14. An intercooler 16 and an intake throttle valve 20 are provided downstream of the compressor 12. The intercooler 16 performs intake air cooling, thereby improving the volumetric efficiency of the intake air of the engine 1 and thereby increasing the output. The intake throttle valve 20 is a normally open valve that adjusts the intake flow rate in a timely manner, and is used for generating negative pressure for increasing the EGR. On the other hand, the turbine 13 of the supercharger 11 is provided in the exhaust passage 9, and the exhaust gas purifying device 17 is provided downstream thereof.

The fuel injection device A of the engine 1 includes a fuel supply device 19, a fuel injection valve 2 that injects fuel into the combustion chamber 7, and a controller (engine ECU) 18 that serves as these injection control means.
The fuel injection valve 2 attached to the cylinder head 3 has an exciting coil 21 in its main body, a needle valve 22 that opens when the exciting coil 21 is energized, and is opened and closed by the needle valve 22 and fed from the common rail 23. And a nozzle 24 capable of injecting the high-pressure fuel into the combustion chamber 7.
A glow plug 30 is attached to the cylinder head 3 in the vicinity of the fuel injection valve 2. This is connected to the controller 18 and is driven so as to improve combustion at the time of cold start and operation of the engine.

The fuel supply device 19 includes a common rail 23, a fuel injection pump 25 connected to the common rail 23, a fuel tank 26, and a fuel pressure sensor 27 that outputs a common rail pressure Pr.
The fuel stored in the common rail 23 is supplied via a high-pressure pipe 29 from a fuel injection pump 25 that is driven by the rotational force of the engine 1. A fuel pressure (common rail pressure Pr) signal stored in the common rail 23 is input to the controller 18 by the fuel pressure sensor 27.

  The controller 18 selectively sets one of a plurality of set rail pressures according to the operating conditions of the fuel injection pump 25, that is, the engine 1. Then, a control signal is directly transmitted from the controller 18 to the fuel pressure adjuster 251 so that the common rail pressure Pr detected by the fuel pressure sensor 27 becomes the set rail pressure. Thereby, the fuel pressure can be adjusted so that the pressure Pr in the common rail 23 becomes a set rail pressure that is selectively set. In FIG. 1, reference numeral 31 denotes a fuel return pipe that returns low-pressure oil from the fuel injection valve 2 to the fuel tank 26.

Here, the controller 18 sets the injection control amount based on the detection information from the above-described sensors, and calculates the injection control amount (injection pulse width) for realizing the target injection amount. Thereafter, the fuel pressure regulator 251 of the fuel injection pump 25 is controlled to control the common rail pressure Pr to a set value. Further, each fuel injection valve 2 is set to a single injection mode (by the single injection control means A01 in FIG. 7) M1, a normal (pilot) injection mode (by the normal injection control means A02 in FIG. 7) M2, and a preliminary fuel injection mode ( A function of performing an injection operation with any of M3) by the preliminary fuel injection control means A03 of FIG.
Specifically, the controller 18 drives the fuel injection valve 2 by selectively using three injection methods.
[Normal injection mode]
As shown in FIG. 2A, when the controller 18 selects the normal injection mode M2, the fuel injection valve 2 performs the main injection injected at the drive pulse width Tm at the injection timing tm and the injection timing tp preceding this. Pilot injection is performed with the drive pulse width Tp. At this time, as shown in FIG. 2B, the fuel injection valve 2 performs the injection with the injection amount Qp corresponding to the drive pulse width Tp and the injection amount Qm corresponding to the drive pulse width Tm. In this normal injection mode M2, fuel injection at the target injection amount is performed separately for main injection Tm and pilot injection Tp.
[Single injection mode]
As shown in FIG. 3A, when the controller 18 selects the single injection mode M1, the fuel injection valve 2 performs single injection that is injected at the injection timing td with the drive pulse width Td. At this time, as shown in FIG. 3B, the fuel injection valve 2 performs the injection with the injection amount Qd corresponding to the drive pulse width Td. In the single injection mode M1, fuel injection of the target injection amount is performed only by the single injection Td. Here, as will be described later, at the basic rotational speed N1 (target rotational speed) that is a predetermined idle rotational speed, the basic injection Td1 that is a single injection is determined by the first feedback control, and the drive pulse width at that time is stored. It is processed.
[Preliminary fuel injection mode]
In the preliminary fuel injection modes M3 and M4 shown in FIGS. 4 (a), 4 (b), 5 (a), and 5 (b), the second feedback control is performed while the basic engine speed N1 that is a predetermined idle engine speed is maintained. Is done.
In the preliminary fuel injection mode M3, basic injection Td1 performed at the injection timing td and preliminary fuel injection (driving pulse width Ta) performed at the injection timing ta preceding this are executed. The drive pulse width Ta at this time is stored in the controller 18.
The basic injection Td1 injected in the preliminary fuel injection mode M3 is an injection at the injection timing td where the basic injection amount Qd1 shown in FIGS. 3A and 3B is retarded to the expansion stroke side. This basic injection Td1 is performed, for example, with the injection timing td fixed at ATDC: 10 °.

In the preliminary fuel injection mode M4, the basic injection Tm1 performed at the injection timing tm, the pilot injection Tp performed at the injection timing tp preceding this, and the preliminary fuel injection (drive pulse width Ta) performed at the injection timing ta preceding this. Are executed. The drive pulse width Ta of the preliminary fuel injection at this time is stored in the controller 18.
The basic injections Tm1 and Tp injected in the preliminary fuel injection mode M4 include the injection amount Qp in the pilot injection Tp and the injection amount Qm1 in the main injection Tm shown in FIGS. The fuel is injected at the injection timings tp and tm retarded to the side. The injection in this case is also performed, for example, with the injection timing tp fixed at ATDC: 10 °, as in the preliminary fuel injection mode M3.

  Hereinafter, the preliminary injection mode M3 of FIG. 4 will be described as an example. As shown in FIG. 6, when the basic injection Td1 is retarded, the output generation amount is reduced and the engine speed is reduced despite injection of the same basic injection amount Qd1 as that in the single injection mode M1. Decreases. Therefore, in order to compensate for the decrease in the engine speed, the injection amount qa necessary for maintaining the engine speed (the basic engine speed N1 that is the idling engine speed) by the second feedback control is changed to the single injection Td1 (main injection). Prior to injection, injection is performed at a predetermined injection timing (for example, BTDC 5 °). This injection is the preliminary fuel injection Ta, and the injection amount at this time is the preliminary fuel injection amount qa.

As a result, the second feedback control for holding the basic rotation speed N1 that is the idle rotation speed is performed, and the drive pulse width Ta of the preliminary fuel injection at that time is stored in the controller 18. The drive pulse width Ta is stored for each cylinder (Ta # 1 to Ta # 4) as will be described later. Such a preliminary fuel injection mode M3 is employed only when the engine 1 is in a predetermined operating range. The predetermined operating range here is set as a case where the basic engine speed N1 is a predetermined idle engine speed and the engine load is zero.
The situation described above using the preliminary injection mode M3 as an example is the same for the preliminary injection mode M4.

  As shown in FIG. 1, the controller 18 includes an input / output device (not shown), a storage device (ROM, RAM, DRAM, etc.) used for storing control programs and control maps, a central processing unit (CPU), a timer (not shown). A counter is provided. On the input end side of the controller 18, an accelerator sensor 32 for detecting an accelerator operation amount θa, an air flow sensor 15, a crank angle sensor 21 for detecting crank angle information Δθ, a fuel pressure sensor 27 for detecting a common rail pressure Pr, and a water temperature wt. Various sensors such as a water temperature sensor 28 to detect, a vehicle speed sensor 33 for detecting the vehicle speed Vc, an air conditioner switch 40, and an intake pressure sensor 60 for detecting the pressure Pb in the intake pipe are connected. The crank angle information Δθ here is used by the controller 18 to derive the engine speed Ne.

On the other hand, various devices such as the fuel injection valve 2, the fuel injection pump 25, the glow plug 30, and the intake throttle valve 20 are connected to the output side of the controller 18.
The controller 18 performs a well-known engine control function and also functions as an engine fuel injection device A that characterizes the present invention. As shown in FIG. 7, the controller 18 includes a single injection control means A01, a normal injection control means A02, a preliminary fuel injection control means A03, a target injection amount setting means A1, a pulse width storage means A2, and a correction means A3. I have. Here, the single injection control means A01, the normal injection control means A02, and the auxiliary fuel injection control means A03 exhibit a control function in association with each other, and these means constitute the fuel injection control means A0. Yes. The fuel injection control means A0 selectively drives the single injection control means A01, the normal injection control means A02, and the preliminary fuel injection control means A03 according to the operation information at that time.

The target injection amount setting means A1 of the fuel injection device A takes in the accelerator opening θa, the engine rotational speed Ne, and the like, which are engine operation information, for each cylinder of the engine 1, and obtains the basic fuel injection amount INJb based on these.
The pulse width storage means A2 is performing single injection when it is determined that the engine has reached the idle operation range, and at the time of basic injection amount measurement (S0) at the start of measurement after entering idle operation control. The basic injection Td1 is determined by the first feedback control, and the drive pulse widths Td1 # 1 to Td1 # 4 for each cylinder at that time are stored (control function of the first feedback control means Af1). Thereafter, in the preliminary injection amount measurement (S1), the second feedback control is entered, and the drive pulse width of the preliminary fuel injection Ta, which is the result of feedback control so that the engine reaches the target rotational speed, is stored.

In the second feedback control, the preliminary fuel injection amount qa is adjusted so as to maintain the basic rotational speed N1. Then, the operation in the preliminary fuel injection mode M3 that maintains the basic rotational speed N1 is performed during the preliminary injection amount measurement (S1), and the drive pulse width (Ta # 1 to Ta # 4) for each cylinder at that time is determined by the controller. 18 and stored (control function of second feedback control means Af2).
The correction means A3 takes in and learns the drive pulse widths Ta # 1 to Ta # 4 for each cylinder stored in the second feedback control means Af2 of the pulse width storage means A2, and corrects the drive pulse width corresponding to the target injection amount. I do.

Note that the amount of preliminary fuel injection amount qa required in accordance with the retard amount of the basic injection Td1 is stored in advance in the learning preliminary injection amount map or the like in the controller 18.
Next, each control process of the controller 18 of FIG. 1 will be described along the idle control routine of FIG. 8 and the injection amount calculation routine of FIG. These routines are executed at predetermined time intervals by the CPU in the controller 18.
When the control process of the controller 18 shifts to the idle control routine, first, in step s1, the intake air amount sensor 15, the crank angle sensor 21, the fuel pressure sensor 27, the water temperature sensor 28, the accelerator opening sensor 32, the vehicle speed sensor 33, the air conditioner switch 40, Based on various signals from the intake pressure sensor 60 and the like, each operation information of the intake air amount Qa, the engine speed Ne, the fuel pressure Pr, the cooling water temperature wt, the accelerator opening degree θa, the vehicle speed Vc, the air conditioner signal Sa, and the intake pressure Pb, respectively. Is read.

Subsequently, in step s2, it is determined whether or not the engine 1 is in an idle state that is a predetermined operating range set in advance. This determination is made based on the engine speed Ne being a predetermined idle speed N1, the accelerator opening θa being fully closed, the vehicle speed Vc being equal to or less than the stop determination value, and the like. If the engine is not in the idle state, the process proceeds to step s4, the process proceeds to the fuel injection amount control process during non-idle operation, and the process returns to the main routine (not shown). On the other hand, if it is in the idling speed range, the process proceeds to step s3.
In step s3, it is determined whether or not the coolant temperature wt read this time is higher than the warm-up determination value wt1, and if it is lower, it is determined that the warm-up is not yet performed, and the process returns to a main routine (not shown).

On the other hand, when the cooling water temperature wt exceeds the warm air determination value wt1 in step s3, it is determined that the engine is idling after warm air. Here, the process proceeds to step s5 and enters a feedback control (ISC) in which the engine speed Ne is corrected so as to maintain the target idle speed N1 assuming that it is in a predetermined idle operating range. Note that the target idle speed N1 here is set in advance to a value that can cope with engine load, for example, driving in the case of air-conditioner driving.
When the process proceeds to step s6 through step s5, an injection amount calculation process is performed here.

As shown in FIG. 9, in this injection amount calculation process, at the time of basic injection amount measurement (S0) after it is determined in step a1 that the engine has reached the idle operation region, the fuel injection valve 2 of each cylinder. In the standard single injection mode M1, the first feedback control is performed so as to maintain the idle speed N1. Then, the drive pulse width Td1 # 1 of one cylinder is measured and stored. Subsequently, similarly, the drive pulse width Td1 # 2 of one cylinder (for example, No. 2 cylinder) is measured and stored, and the drive pulse widths Td1 # 3 and Td1 # 4 are sequentially measured for No. 3 and 4 cylinders. The data is stored in a storage area in the controller 18.
In step a2, it is confirmed whether or not the current operation region is in the idle operation region while maintaining the idle speed N1. When it is not in the idling range, the process returns to step s5 of the idling control routine.

When the result of step a2 is Yes and the process proceeds to step a3, the fuel injection valve 2 is driven in the preliminary fuel injection mode M3 (see FIG. 4) at the time of preliminary injection amount measurement (S1). At this time, the second feedback control is performed so as to maintain the basic rotational speed N1, and the drive pulse width Ta at the time of preliminary fuel injection is adjusted.
Next, at step a4, it is determined whether or not the basic rotational speed N1 is stable. When the process proceeds to the No side in step a4, the process proceeds to step s5 ′, and the same ISC control as in step s5 described above is performed to stabilize the basic rotational speed N1.

When the basic rotational speed N1 is stabilized and the process proceeds to step a5, the drive pulse widths Ta # 1 to Ta # 4 of each cylinder at the time of preliminary injection amount measurement (S1) are measured and stored in a predetermined storage area of the controller 18 here. Is done.
After performing the processing in step s6 (injection amount calculation processing in FIG. 9), the process proceeds to step s7. Here, the learning results of the drive pulse widths Ta # 1 to Ta # 4 for each cylinder are stored at the time of the above learning. Correlate with the pre-injection map. Then, this is reflected in the fuel injection drive control performed in the main routine of the fuel injection device A thereafter, and the injection control of each fuel injection valve 2 is performed.

  In this way, the accuracy of the actual injection amount (injection control amount) with respect to the target injection amount can always be kept appropriate by a relatively simple process. In particular, by reflecting the learning results of the drive pulse widths Ta # 1 to Ta # 4 in the fuel injection drive control, it is possible to more accurately vary the small amount of injection without being affected by individual differences of the fuel injection valves 2 or deterioration over time. Therefore, the fuel injection control can be performed more finely and accurately, so that the generation of smoke and noise can be suppressed.

  In the present embodiment, it has been described that the controller 18 selectively learns each cylinder by setting one of a plurality of rail pressures. However, each cylinder is learned for one rail pressure Pr1. Thereafter, learning of each cylinder can be performed sequentially for other rail pressures (Pr2, Pr3, etc.). Thus, accurate fuel injection control can be maintained without being affected by the set injection pressure that varies depending on the operating range.

It is a schematic block diagram of the engine provided with the fuel-injection apparatus of the engine as one Embodiment of this invention. FIG. 2 is a characteristic explanatory diagram of a normal injection mode performed by the fuel injection device of FIG. 1. It is a characteristic explanatory view of the single injection mode which the fuel injection device of the engine of FIG. 1 performs. FIG. 2 is a characteristic explanatory diagram of a preliminary fuel injection mode performed by the fuel injection device of FIG. 1. FIG. 2 is a characteristic explanatory diagram of a preliminary fuel injection mode performed by the fuel injection device of FIG. 1. It is switching control characteristic explanatory drawing of the single injection mode of the fuel-injection apparatus of FIG. 1, and a preliminary | backup fuel injection mode. It is a functional block diagram of the fuel-injection apparatus of FIG. 3 is a flowchart of an idle operation control routine of the fuel injection device of FIG. 1. It is a flowchart of the injection amount calculation process routine of the fuel injection device of FIG. It is a noise with respect to the pilot injection quantity in a conventional internal combustion engine, and a smoke characteristic diagram.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Fuel injection valve 18 Controller 19 Fuel supply apparatus A Fuel injection apparatus A0 Fuel injection drive means A01 Single injection control means A02 Normal injection control means A03 Preliminary fuel injection control means A1 Target injection amount calculation means A2 First measurement time calculation means A3 Correction means Af1 First feedback control means Af2 Second feedback control means

Claims (3)

A fuel injection valve provided in the cylinder of the engine;
When the engine is in a predetermined operating range, the fuel injection amount is controlled to feedback-control the engine speed to a predetermined target speed, and the control result of the fuel injection amount is stored as a basic fuel injection amount First feedback control means;
When in the predetermined operating range, the basic fuel injection amount of fuel is injected at a retarded injection timing delayed from the injection timing of fuel injection at the time of control by the first feedback control means, and the retarded angle Preliminary fuel injection is performed separately from the basic fuel injection amount at an injection timing advanced from the injection timing, and the engine speed is fed back to the predetermined target speed by controlling the injection amount of the preliminary fuel injection. Second feedback control means for controlling and storing the control result of the injection amount of the preliminary fuel injection as a corrected fuel injection amount;
Correction means for correcting a control command for the fuel injection valve at normal time based on the corrected fuel injection amount;
An engine fuel injection device comprising: The fuel injection device for an engine according to claim 1,
The engine is a multi-cylinder engine having a plurality of cylinders;
The fuel injection valve is provided in each of the plurality of cylinders;
The engine fuel injection device, wherein the correction means corrects a control command for each of the fuel injection valves for each of the plurality of cylinders. The engine fuel injection device according to claim 1 or 2,
The engine fuel injection device, wherein the predetermined operating range is an idle operating range.

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