JP2003232244A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

(57) Abstract: Provided is a fuel injection control device for an internal combustion engine having an electromagnetically driven fuel injection valve, which can more accurately control a fuel injection mode at a low temperature start. The device includes an electromagnetically driven fuel injection valve (2). The fuel injection valve 2 has an armature whose electromagnetic force is generated by an electromagnetic force generated by energizing the electromagnetic coil 43.
The valve is opened by being sucked to the side. The injection timing and injection amount of the fuel injected from the fuel injection valve 2 are determined by the electromagnetic coil 43.
It is controlled according to the power supply timing and power supply time. Institution 1
The amount of fuel injected from the fuel injection valve 2 is reduced based on the elapsed time after the start operation and the estimated temperature of the fuel injection valve 2. The decrease correction amount is set to be larger as the elapsed time after the start operation of the engine 1 is shorter and as the estimated temperature of the fuel injection valve 2 is lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for an internal combustion engine provided with an electromagnetically driven fuel injection valve.

[0002]

2. Description of the Related Art In a fuel injection control device of this type used in, for example, a common rail type diesel engine, various control variables such as an injection timing and an injection time are controlled based on an engine operating state when controlling fuel injection. The fuel injection valve is obtained and the drive control of the fuel injection valve is performed based on the obtained control amount. As a result, basically, an amount of fuel suitable for the engine operating condition at each time is injected and supplied to the internal combustion engine, and the operation of the engine is appropriately maintained.

However, as is well known, the bulk elastic modulus and viscosity of the fuel usually decrease as the temperature of the fuel rises. This causes a decrease in the fuel pumping efficiency, such as a decrease in the valve opening speed of the fuel injection valve and an increase in the amount of fuel leakage from various valves provided in the fuel supply passage.

Therefore, even when the fuel injection valve is driven to open for the same time, different amounts of fuel from the same fuel injection valve are supplied to the internal combustion engine depending on whether the fuel temperature is high or low. The fuel is supplied by injection, which in turn causes an unnecessary change in the cylinder internal pressure of the internal combustion engine. This is one of the causes of inconveniences such as deterioration of durability of the internal combustion engine and instability of engine output due to excessive increase in cylinder pressure.

Therefore, conventionally, for example, Japanese Patent Laid-Open No. 9-6054 is used.
As disclosed in Japanese Patent Laid-Open No. 2 (1994), there is proposed a device that detects the fuel temperature and corrects the valve opening time of the fuel injection valve, that is, the injection time (injection amount) according to the detected fuel temperature. By performing such a correction process, it becomes possible to inject and supply a desired amount of fuel to the internal combustion engine regardless of the temperature of the fuel, and it is possible to suppress the above-mentioned unnecessary change in the cylinder pressure. Like

[0006]

An electromagnetically driven fuel injection valve normally has a needle 41 as a valve body and a spring 42 for urging the needle 41 in the valve closing direction, as illustrated in FIG. , Electromagnetic coil 43, and armature 44
And a spring 45 for urging the armature 44 in a direction of separating the armature 44 from the electromagnetic coil 43 are integrally housed in a case 46. Further, in the case 46, there are provided a fuel passage connected to a fuel accumulation pipe (common rail) and a return pipe to a fuel tank, including an injection hole 47 for injecting fuel into a cylinder of an internal combustion engine. Has been.

When the fuel injection valve is opened, the electromagnetic coil 43 is energized to move the armature 44 in a direction against the urging force of the spring 45, that is, in a direction in which the armature 44 is attracted to the electromagnetic coil 43 side. . As a result, the pressure balance between the fuel passages connected to the common rail and the return pipe is changed, and the needle 41 is accordingly changed.
Are moved in a direction that allows the injection hole 47 and the common rail to communicate with each other. That is, fuel injection from the injection hole 47 is started.

On the other hand, when driving the fuel injection valve to close, the energization of the electromagnetic coil 43 is stopped. This allows
The armature 44 is moved by the biasing force of the spring 42 in FIG.
Move to the position shown in. At this time, the fuel passage is also cut off and the pressure balance is maintained, so that the needle 41 causes the injection hole 47 to move by the urging force of the spring 42.
It is moved in the direction of blocking communication with the common rail.
That is, the fuel injection from the injection hole 47 is stopped.

In the fuel injection valve having such a structure, in order to accurately inject and supply a desired amount of fuel to the internal combustion engine, the magnetic flux acting on the armature 44, in other words, the attraction force is applied to the electromagnetic coil. It is desirable to control accurately through 43. However, the attraction force acting on the armature 44 may unnecessarily increase in a very short period immediately after the cold start of the engine even under the condition that the amount of current supplied to the electromagnetic coil 43 is constant. Have been confirmed by others.

The reason will be described below with reference to FIGS. 6 to 8. Normally, when the operation of the internal combustion engine is started, the armature 44 starts sliding along with the fuel injection valve, and frictional heat is generated on the sliding surface. Here, since the armature 44 has an extremely small volume as compared with the case 46 of the fuel injection valve, the heat capacity is also small. Therefore, when the engine is cold-started, that is, when the temperature of the fuel injection valve is low, the temperature of the armature 44 first rises. Then, after that, when the drive control of the fuel injection valve is continued, the temperature of the case 46 also gradually rises, and accordingly, the temperature difference between them also gradually becomes smaller. In other words, if attention is paid to a very short period immediately after the cold start of the engine, a large difference will occur in the amount of thermal expansion between the armature 44 and the case 46.

Depending on the fuel injection valve, due to such a difference in the amount of thermal expansion, the electromagnetic coil 4 in the valve open state may be changed.
The gap Gp between 3 and the armature 44 is temporarily reduced. That is, as shown in FIG. 6 which shows the relationship between the gap Gp and the attraction force acting on the armature 44, even if the electromagnetic force generated by the electromagnetic coil 43 is constant,
As the gap Gp becomes smaller, the suction force acting on the armature 44 becomes larger.

Therefore, as shown in FIG. 7 as an example of the transition of the lift amount of the armature 44, when the gap Gp is small at the time of starting fuel injection, when the gap Gp becomes small, as shown in FIG.
As indicated by the alternate long and short dash line, the lift speed and the lift timing of the armature 44 in the valve opening direction are faster than in the steady state (solid line) in which the gap Gp is not small. As a result, as shown in FIG. 8, the fuel injection rate is higher when the gap Gp shown by the alternate long and short dash line in FIG. 8 is smaller than the steady-state fuel injection rate shown by the solid line. As a result, the fuel injection amount is unnecessarily increased.

Further, as the lift speed and lift timing of the armature 44 in the valve opening direction are increased in this way, the total amount of magnetic flux acting on the armature 44 in one fuel injection increases. That is, the magnetic flux remaining in the magnetic circuit becomes large when the power supply to the electromagnetic coil 43 is stopped. Therefore, even after the power supply to the electromagnetic coil 43 is stopped, the decrease in the magnetic flux acting on the armature 44 is prolonged,
As a result, the lift speed and lift timing of the armature 44 in the valve closing direction also become slower (see FIG. 7). As a result, the decrease in the fuel injection rate is delayed by that amount (see FIG. 8), and this also inevitably causes an unnecessary increase in the fuel injection amount.

Such an unnecessary increase in the amount of fuel injection at the time of engine cold start eventually leads to an unnecessary increase in the cylinder internal pressure of the internal combustion engine, and when this becomes excessive, the durability of the internal combustion engine is reduced. Will also have an effect.

As described above, in the case of detecting the fuel temperature, the temperature of each part of the fuel injection valve is estimated based on the detected fuel temperature, and based on the estimated temperature of each part. It is also conceivable to compensate the unnecessary increase in the fuel injection amount described above by correcting the fuel injection amount in a reduced amount. However, the electromagnetic coil 43 and the armature 44 described above
The reduction of the gap Gp between and occurs only in a very short period immediately after the engine cold start, whereas the fuel temperature hardly changes within such a period. Therefore, the correction of the reduction of the fuel injection amount based on the fuel temperature alone does not solve the above problem.

The present invention has been made in view of the above circumstances, and an object thereof is to more accurately control the fuel injection mode at the cold start of an internal combustion engine having a fuel injection valve electromagnetically driven. An object of the present invention is to provide a fuel injection control device for an internal combustion engine that can do the above.

[0017]

[Means for Solving the Problems] Means for achieving the above-mentioned objects and their effects will be described below. First, the invention according to claim 1 is provided with an electromagnetically driven fuel injection valve in which a fuel injection mode is determined through an armature lift operation based on energization of an electromagnetic coil, and a fuel supplied to the fuel injection valve is supplied. In a fuel injection control device for an internal combustion engine in which an injection timing and an injection amount with respect to an internal combustion engine are controlled according to an energization timing and an energization time to the electromagnetic coil, in the cold start of the engine, the electromagnetic coil and the armature are The gist of the present invention is to include a correction unit that corrects the change in the fuel injection mode due to the change in the gap.

According to the above construction, the engine is cold-started, in other words, the engine is started when the temperature of the fuel injection valve is low, so that the gap between the electromagnetic coil and the armature is temporarily changed. Even in such a case, it becomes possible to correct the change in the fuel injection mode due to the change in the gap. Therefore, the internal combustion engine including the electromagnetically driven fuel injection valve can more accurately control the fuel injection mode during cold start.

The invention described in claim 2 is the same as claim 1.
In the fuel injection control device for an internal combustion engine as described above, the fuel injection valve is opened in response to a lift operation in a direction in which the armature is attracted to the electromagnetic coil side by energizing the electromagnetic coil. The gist of the correction means is to reduce the amount of fuel injected from the fuel injection valve based on the elapsed time after the starting operation of the engine and the estimated temperature of the fuel injection valve. .

According to the above construction, when the amount of fuel injected from the fuel injection valve unnecessarily increases with the temporary reduction of the gap between the electromagnetic coil and the armature, the elapsed time after the engine starting operation and the fuel It is possible to obtain the degree of reduction of the gap based on the estimated temperature of the injection valve and correct the amount of fuel reduction according to the obtained degree of reduction. Therefore, it becomes possible to suitably compensate for an unnecessary increase in the amount of fuel injected from the fuel injection valve.

The invention described in claim 3 is the same as that of claim 2
In the fuel injection control device for the internal combustion engine according to the description, the correction means, the shorter the elapsed time after the starting operation of the engine,
The gist of the invention is that the lower the estimated temperature of the fuel injection valve is, the larger the correction amount for reducing the amount of fuel injected from the fuel injection valve is.

The degree of reduction of the above-described gap, and consequently the degree of increase of the amount of fuel injected from the fuel injection valve, is greater as the elapsed time after the engine starting operation is shorter and the temperature of the fuel injection valve is lower. . In this respect, according to the above configuration, it is possible to perform the reduction correction for the fuel amount according to such a tendency, and it is possible to suitably compensate for the unnecessary increase.

The invention described in claim 4 is the same as in claim 1.
In the fuel injection control device for an internal combustion engine as described above, the fuel injection valve is opened in response to a lift operation in a direction in which the armature is attracted to the electromagnetic coil side by energizing the electromagnetic coil. The gist of the correction means is to correct the pressure of fuel supplied to the fuel injection valve based on the elapsed time after the engine starting operation and the estimated temperature of the fuel injection valve. To do.

The invention according to claim 5 is the invention according to claim 4
In the fuel injection control device for the internal combustion engine according to the description, the correction means, the shorter the elapsed time after the starting operation of the engine,
The gist is that the lower the estimated temperature of the fuel injection valve, the larger the decompression correction amount of the pressure of the fuel supplied to the fuel injection valve.

As is well known, when the pressure (injection pressure) of the fuel supplied to the fuel injection valve is reduced, the amount of fuel injected from the valve decreases. Therefore, according to the invention described in claim 4, the same effect as that of the invention described in claim 2 can be obtained by performing the pressure reduction correction of the injection pressure in accordance with the degree of reduction of the gap. According to the invention, the same effect as that of the invention described in claim 3 can be obtained.

The invention according to claim 6 is the same as claim 1.
In the fuel injection control device for an internal combustion engine as described above, the fuel injection valve is opened in response to a lift operation in a direction in which the armature is attracted to the electromagnetic coil side by energizing the electromagnetic coil. The correction means retards the injection timing of the fuel injected from the fuel injection valve based on the elapsed time after the starting operation of the engine and the estimated temperature of the fuel injection valve. Use as a summary.

As is also well known, when the injection timing of the fuel injected from the fuel injection valve is retarded, the peak value of the in-cylinder pressure in the internal combustion engine decreases. Therefore,
According to the above configuration, the injection timing is retarded according to the degree of reduction of the gap, so that an unnecessary increase in the in-cylinder pressure associated with the temporary reduction of the gap can be appropriately suppressed. become able to.

The invention according to claim 7 is the same as claim 6
In the fuel injection control device for the internal combustion engine according to the description, the correction means, the shorter the elapsed time after the starting operation of the engine,
The gist of the invention is that the lower the estimated temperature of the fuel injection valve, the larger the retard correction amount of the injection timing of the fuel injected from the fuel injection valve.

When the pressure in the cylinder rises due to the temporary reduction of the gap, the degree of rise is larger as the elapsed time after the engine starting operation is shorter and the temperature of the fuel injection valve is lower. In this respect, according to the above configuration,
It becomes possible to correct the injection timing retard according to such a tendency, and it is possible to suitably compensate for the unnecessary increase in the cylinder pressure.

The invention described in claim 8 is the same as claim 1.
In the fuel injection control device for an internal combustion engine as described above, the fuel injection valve is opened in response to a lift operation in a direction in which the armature is attracted to the electromagnetic coil side by energizing the electromagnetic coil. The correction means corrects the decrease in the amount of fuel injected from the fuel injection valve based on the elapsed time after the starting operation of the engine and the estimated temperature of the fuel injection valve, and supplies the fuel to the fuel injection valve. The gist of the invention is to perform at least one of the correction of the pressure decrease of the fuel and the correction of the retardation of the injection timing of the fuel injected from the fuel injection valve.

The invention described in claim 9 is the same as that of claim 8.
In the fuel injection control device for the internal combustion engine according to the description, the correction means, the shorter the elapsed time after the starting operation of the engine,
Further, the lower the estimated temperature of the fuel injection valve, the larger the reduction correction amount for the fuel amount injected from the fuel injection valve, and the decompression correction amount for the pressure of the fuel supplied to the fuel injection valve. Is made large, and the gist is to make the retard correction amount large for the injection timing of the fuel injected from the fuel injection valve.

According to the invention as set forth in claim 8 or claim 9, an unnecessary increase in the amount of fuel injected from the fuel injection valve and an unnecessary increase in the cylinder pressure are caused by the temporary reduction of the gap. Together, or at least an unnecessary increase in cylinder pressure can be suitably compensated.

When the temperature of the fuel injection valve is estimated, the temperature of the fuel injection valve is estimated on the basis of the engine parameter on which the temperature is preferably reflected, that is, on the basis of the engine cooling water temperature, for example. It is possible to employ a configuration in which the estimation is performed based on the temperature of the air sucked into the engine. Both the temperature of the cooling water and the temperature of the intake air can be measured by a sensor normally provided in the internal combustion engine, and a new sensor or the like is not necessary when estimating the temperature of the fuel injection valve. It should be noted that, if space or cost allowance, a sensor or the like for directly measuring the temperature of each portion of the fuel injection valve may be provided.

According to a twelfth aspect of the present invention, in the fuel injection control device for an internal combustion engine according to any one of the first to eleventh aspects, the correction means includes the fuel after the start of the engine is completed. The gist is that the correction is executed only for a predetermined period until the temperature of each portion of the injection valve becomes substantially uniform.

According to the above arrangement, the correction for the change in the fuel injection mode is executed only during the period in which the gap may be temporarily reduced, and the more accurate correction according to the actual situation is realized. Become so.

According to a thirteenth aspect of the present invention, in the fuel injection control device for an internal combustion engine according to any one of the first to twelfth aspects, the engine stores the pressure of the fuel supplied to the fuel injection valve. The gist of the invention is to be an in-cylinder injection type internal combustion engine that includes a means and that directly injects the fuel injected from the fuel injection valve into the cylinder.

Normally, in a cylinder injection type internal combustion engine, it is necessary to directly inject and supply fuel into a cylinder in which the internal pressure is increased, so that the fuel is accumulated in the fuel injection valve at an extremely high pressure. Have been supplied. Therefore, when the gap is temporarily reduced and the lift speed or lift timing of the armature changes, an error in the amount of fuel injected from the fuel injection valve due to this changes becomes noticeable. In this respect, according to the above configuration, in such an in-cylinder injection type internal combustion engine, an unnecessary change in the fuel injection mode can be suitably corrected.

The invention of claim 14 is the fuel injection control device for an internal combustion engine according to claim 13, wherein the internal combustion engine is a common rail type diesel engine.

Among the in-cylinder injection type internal combustion engines, the common rail type diesel engine has an extremely high injection pressure because the in-cylinder pressure in the combustion stroke is extremely high. Therefore, when the gap becomes temporarily small, an error in the amount of fuel injected from the fuel injection valve appears remarkably, and the durability of the engine in the case where the in-cylinder pressure increases due to the error Concerns about the decline will increase. In this respect, according to the above configuration, in such a common rail type diesel engine, it is possible to preferably suppress the unnecessary increase in the cylinder pressure that may affect the durability thereof. .

[0040]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a combustion injection control device for an internal combustion engine according to the present invention will be described below with reference to FIGS.
Will be described with reference to.

FIG. 1 shows a schematic structure of a fuel injection control device for an internal combustion engine according to this embodiment, more specifically, a system for fuel injection of a pressure-accumulation (common rail) diesel engine mounted on a vehicle.

As shown in FIG. 1, the diesel engine 1 includes a plurality of cylinders (four cylinders in the present embodiment) # 1 to # 4.
# 4 is provided, and an electromagnetically driven fuel injection valve 2 that injects fuel into the combustion chambers of the cylinders # 1 to # 4 is provided. From the fuel injection valve 2 to each cylinder # 1 to # 4 of the engine 1
Fuel injection is controlled by switching between energization and interruption of energization of the electromagnetic coil 43 provided in the valve 2. In addition, as the fuel injection valve 2, as shown in FIG.
It is assumed that the fuel injection valve has the structure illustrated in FIG.

This fuel injection valve 2 is connected to a common rail 4 as a pressure accumulating pipe common to each cylinder, and while the electromagnetic coil 43 is being energized, that is, while being opened, the common rail 4 is operated. The fuel in 4 is injected from the fuel injection valve 2 into each cylinder # 1 to # 4 of the engine 1. Fuel having a pressure high enough to enable such fuel injection is continuously accumulated in the common rail 4.

The common rail 4 is connected to the discharge port 6a of the fuel pump 6 via the supply pipe 5. A check valve 7 is provided in the middle of the supply pipe 5. The check valve 7 allows the fuel supply from the fuel pump 6 to the common rail 4 and regulates the reverse flow of the fuel from the common rail 4 to the fuel pump 6.

The fuel pump 6 is connected to the fuel tank 8 via the suction port 6b, and a filter 9 is provided in the middle thereof. The fuel pump 6 is driven by reciprocating the plunger by a cam (not shown) synchronized with the rotation of the engine 1. As a result, the fuel pump 6 sucks the fuel from the fuel tank 8 through the filter 9, raises the fuel to a required predetermined pressure, and supplies the fuel to the common rail 4.

Further, a pressure control valve 10 is provided near the discharge port 6a of the fuel pump 6. The pressure control valve 10 closes its valve body in response to the ON signal, and allows the fuel supply from the discharge port 6a toward the common rail 4. Further, the pressure control valve 10 opens its valve body in response to the OFF signal, and the excess fuel not discharged from the discharge port 6a is supplied from the return port 6c provided in the fuel pump 6 through the return pipe 11 to the fuel. It is designed to be returned to the tank 8. The fuel pressure (and thus the discharge amount) discharged from the discharge port 6a to the common rail 4 side is adjusted by the on / off control (open / close valve control) of the pressure control valve 10.

The common rail 4 has a relief valve 12
Is provided, and the relief valve 12 is opened when a predetermined condition is satisfied. As a result, the high-pressure fuel in the common rail 4 is returned to the fuel tank 8 via the return pipe 11, and the pressure in the common rail 4 is reduced.

The engine 1 is provided with the following various sensors and the like to detect its state. That is, an accelerator sensor 21 for detecting the amount of depression (accelerator opening) ACC is provided near the accelerator pedal 15.

Further, in the cylinder block of the engine 1,
Water temperature sensor 2 for detecting the temperature THW of the cooling water
Two are provided. In addition, in the vicinity of an air cleaner (not shown) provided upstream of the intake passage 13 of the engine 1,
An intake air temperature sensor 23 for detecting the temperature THA of the air taken into the engine 1 is provided.

In addition, the return pipe 11 is provided with a fuel temperature sensor 24 for detecting the fuel temperature THF, and the common rail 4 for detecting the fuel pressure (and thus the injection pressure) PF in the common rail 4. Fuel pressure sensors 25 are provided respectively.

Further, in the present embodiment, the crank angle sensor 26 is provided near the pulsar provided on the crankshaft (not shown) of the engine 1. Further, the rotation of the crankshaft is transmitted to a camshaft (not shown) for opening and closing the intake valve 31 and the exhaust valve 32 via a timing belt or the like.

This camshaft is set so as to rotate at a rotation speed of 1/2 rotation of the crankshaft.
A cam angle sensor 27 is provided near the pulser provided on the cam shaft. Then, in the present embodiment, the engine rotation speed NE and the crank angle are calculated from the pulse signals output from both the sensors 26 and 27, and the top dead center of the piston in each of the cylinders # 1 to # 4 is calculated. (Cylinder is determined).

Further, the engine 1 is provided with a starter (not shown) for starting the engine 1. The starter is provided with a starter switch 28 that detects the operating state of the starter. The starter switch 28 is operated by the driver from the OFF position of the ignition switch (not shown) to the start position when the engine 1 is started, and the starter is operated (when the cranking state is set). Signal ST is "on"
Output as. Also, this starter switch 28 is
When the start of the engine 1 is completed (in the autonomous operating state),
Alternatively, when the engine 1 fails to start and the ignition switch is returned from the start position to the ON position, the starter signal ST is output as "OFF".

In the present embodiment, an electronic control unit 33 for controlling various controls of the engine 1 is provided. The electronic control unit 33 takes in the output signals of the accelerator sensor 21, the water temperature sensor 22, the intake air temperature sensor 23, the fuel temperature sensor 24, the fuel pressure sensor 25, the crank angle sensor 26, the cam angle sensor 27, the starter switch 28, etc. . Then, the electronic control unit 33 controls the fuel injection valve 2, the pressure control valve 10, the relief valve 12 and the like according to the operating conditions of the engine 1 which are grasped based on these output signals.

The outline of the fuel injection control according to this embodiment will be described below. The electronic control unit 33 controls the fuel injection from the fuel injection valve 2 as a part of the various controls described above. This fuel injection control is performed as follows.

That is, first, the electronic control unit 33 causes the fuel injection amount ("final injection amount Q" depending on the operating state of the engine 1).
f ”) and the fuel injection timing are calculated. Then, the injection time required for injection of an amount corresponding to the final injection amount Qf calculated above is calculated according to the engine rotational speed NE and the injection pressure PF at that time.

Then, at the fuel injection timing calculated here, the electronic control unit 33 starts energizing the electromagnetic coil 43 of the fuel injection valve 2 to supply the high pressure fuel from the common rail 4 to each cylinder # 1. ~ The injection to # 4 is started. After that, the electromagnetic coil 43 is kept energized for the calculated injection time and a required amount of fuel is injected, and then the electromagnetic coil 43 is de-energized to complete the fuel injection.

Further, the electronic control unit 33 controls the fuel injection pressure (injection pressure) of the fuel accumulated in the common rail 4 while controlling the fuel injection. This injection pressure control is performed as follows.

That is, first, the electronic control unit 33 calculates a reference injection pressure which is a preferable injection pressure according to the engine rotational speed NE and the final injection amount Qf at that time. Then, the electronic control unit 33 includes the pressure control valve 10 and the relief valve 12
Is adjusted to maintain the fuel pressure PF in the common rail 4 at the calculated reference injection pressure.

Here, as described above, in the engine 1, the fuel injection valve 2 is operated for a very short period immediately after the cold start.
A temperature difference occurs between the case 46 and the armature 44, and the gap Gp (FIG. 5) between the electromagnetic coil 43 and the armature 44 is temporarily reduced accordingly. Further, as described above, the amount of fuel injected from the fuel injection valve 2 is unnecessarily increased due to this.

The inventors have confirmed that the degree of temporary reduction of the gap Gp changes depending on the elapsed time after the starting operation of the engine 1 and the temperature of the fuel injection valve 2. Specifically, focusing on the condition that the elapsed time after the starting operation of the engine 1 is constant, the lower the temperature of the fuel injection valve 2, the larger the temperature difference and the smaller the gap Gp. Further, when the drive control of the engine 1 and by extension the fuel injection valve 2 is continued, the temperature difference is gradually reduced accordingly, and the temporary reduction of the gap Gp is also eliminated.

Therefore, in the present embodiment, paying attention to such a changing tendency of the gap Gp, the final injection amount Qf is reduced and corrected based on the elapsed time after the starting operation of the engine 1 and the estimated temperature of the fuel injection valve 2. Thus, the unnecessary increase in the amount of fuel injected from the valve 2 is compensated. In this embodiment, the temperature of the fuel injection valve 2 is estimated based on the intake air temperature THA. Specifically, as the estimated temperature of the fuel injection valve 2, the intake air temperature THA, which is an engine parameter in which the same temperature is appropriately reflected, is substituted.

Specifically, as a tendency of the above correction, as shown in FIG. 2, a map used for calculating the correction coefficient K1 calculated at the time of the correction, the intake air temperature THA is lower and the elapsed time after the engine is started is increased. The shorter the value, the larger the correction coefficient K1 is calculated. In addition,
The correction coefficient K1 is calculated as a number of "1" or more.

Then, the target injection amount Qt is calculated from the following equation (1) based on the final injection amount Qf and the correction coefficient K1, and the calculated target injection amount Q is also calculated.
The injection time is calculated based on t. Target injection amount Qt ← Qf × (1 / K1) (1) As a result, the larger the correction coefficient K1 is calculated, the more the target injection amount Qt is reduced (the injection time is shortened). Therefore, the unnecessary increase in the amount of fuel injected from the fuel injection valve 2 caused by the temporary reduction of the gap Gp is compensated.

The detailed procedure of the injection time calculation process including the correction process when the engine 1 is started at a low temperature will be described below with reference to the flowchart shown in FIG. The series of processes shown in this flowchart are repeatedly executed by the electronic control unit 33 at a predetermined control cycle. Further, this processing is executed only after the engine 1 is in the autonomous operating state, that is, after the start is completed.

In this process, first, the sensors 21 to 2 are
7 and the starter switch 28, each engine parameter ACC, THW, THA, THF, PF, NE, ST
Is detected (step S100). After that, the operating state of the engine 1 is determined based on these engine parameters, and then the final injection amount Qf, the fuel injection timing, and the reference injection pressure corresponding to the operating state are calculated as described above ( Step S101).

Then, the cold start correction process is executed (steps S102 to S105). In this process, first, it is determined whether all of the following (condition a) to (condition c) are satisfied (step S102). (Condition a): The cooling water temperature THW is lower than a predetermined temperature T1 (for example, 0 ° C.). (Condition b): The intake air temperature THA is lower than the predetermined temperature T2 (for example, 0 ° C.). (Condition c): The elapsed time after the engine starting operation, that is, the elapsed time after the starter signal ST is turned on is less than a predetermined time C (for example, 5 minutes).

The predetermined temperatures T1 and T2 and the predetermined time C are the predetermined period (condition a) from the completion of the engine start until the temperature of each part of the fuel injection valve becomes substantially uniform. A value that can be determined through (condition c) is set in advance after being obtained by an experiment or the like. Specifically, by satisfying all of these (condition a) to (condition c), the gap Gp is temporarily reduced, and accordingly, the unnecessary increase in the amount of fuel injected from the fuel injection valve 2 is accompanied. It is judged that there is a risk of being invited.

When all of these (condition a) to (condition c) are satisfied (step S102: YE
S), assuming that the amount of fuel injected from the fuel injection valve 2 may unnecessarily increase, the correction coefficient K1 is calculated based on the map shown in FIG. 2 as described above (step S103). ). The above map is a map for calculating the correction coefficient K1 from the intake air temperature THA and the elapsed time after the engine is started. The relationship between the intake temperature THA, the elapsed time after the engine is started, and the correction coefficient K1 is experimentally determined. After being obtained, it is stored in an appropriate memory of the electronic control unit 33 in advance.

On the other hand, if any one of the above (condition a) to (condition c) is not satisfied (step S10)
2: NO), and the correction coefficient K1 is set to "1" (step S104) on the assumption that the amount of fuel injected from the fuel injection valve 2 does not unnecessarily increase.

After the correction coefficient K1 is calculated or set in this way, the target injection amount Qt is calculated from the equation (1) based on the correction coefficient K1 and the final injection amount Qf (step S105).

Then, based on the engine rotational speed NE and the injection pressure PF, the injection time required for injecting and supplying the engine 1 with an amount of fuel corresponding to the target injection amount Qt is calculated. (Step S106).

Hereinafter, how the above-described fuel injection control is specifically performed will be described with reference to the timing chart shown in FIG. Note that FIG. 4 shows an example of the transition of the correction amount for the target injection amount Qt when the fuel injection control according to the present embodiment is applied to the engine 1 in which the post-start increase process is also performed. This post-starting amount increase process is a process executed to stabilize the engine rotational speed NE immediately after the engine 1 is in the complete explosion state, and the correction coefficient K2 for the target injection amount Qt is the cooling water temperature THW.
It is set based on. Specifically, this correction coefficient K2 is
The lower the cooling water temperature THW, the larger the calculated value. The correction coefficient K2 is calculated as a number of "1" or more. The target injection amount Qt is the final injection amount Q.
It is calculated from the following equation based on f and the correction coefficients K1 and K2. Qt = Qf × (1 / K1) × K2 Now, when the starting operation of the engine 1 is performed (timing t
1) After that, during the period until the engine 1 enters the autonomous operation state (timing t1 to t2), the above-described low temperature start correction process and the post-start increase amount process are not executed, and the autonomous operation of the engine 1 is performed through a separate process. A target injection amount Qt that enables a smooth transition to the operating state is calculated. Therefore, during this period, the correction amount for the target injection amount Qt is set to "0".

After that, when the engine 1 enters the autonomous operating state (timing t2), both the low temperature start correction process and the post-start increase process are started. At this time, in the post-starting amount increase processing, the correction coefficient K2 is calculated as a value for increasing the target injection amount Qt by the amount indicated by the arrow D in FIG.
On the contrary, in the low temperature start correction process, the arrow E in FIG.
The correction coefficient K1 is calculated as a value that reduces the target injection amount Qt by the amount indicated by. Therefore, the correction amount for the target injection amount Qt at this time is calculated by the correction coefficients K1, K
The amount corresponds to a value obtained by multiplying by 2 (in this example, the target injection amount Qt is set to the amount on the side of decreasing).

After that, when the operation of the engine 1 is continued (after the timing t2), the cooling water temperature THW gradually rises. Along with this, as indicated by the alternate long and short dash line in FIG. 4, the correction coefficient K2 calculated by the post-start increase processing is
The amount of increase in the target injection amount Qt is gradually reduced. On the other hand, the correction coefficient K1 calculated by the low temperature start correction process changes so as to gradually reduce the degree of decrease in the target injection amount Qt. Then, the correction amount at this time changes corresponding to the value obtained by multiplying the correction coefficients K1 and K2 as shown by the solid line in FIG. 4 (in this example, the target injection amount Qt is gradually increased). Transition to).

In the low temperature start correction process, when the correction coefficient K1 calculated from the map (FIG. 2) becomes "1" (timing t3), the correction amount is calculated by the post-start increase process. It changes according to the change of the correction coefficient K2. That is, the amount of increase in the target injection amount Qt is gradually reduced (after the timing t3).

After that, when the cooling water temperature THW rises sufficiently and the correction coefficient K1 calculated by the post-start increase processing becomes "1" (timing t4), the correction amount becomes "0".

As described above, according to this embodiment, the effects described below can be obtained. (1) In the present embodiment, the target injection amount Q is calculated based on the elapsed time after the starting operation of the engine 1 and the estimated temperature of the fuel injection valve 2.
The amount t is corrected to be reduced. As a result, when the amount of fuel injected from the fuel injection valve 2 unnecessarily increases with the temporary reduction of the gap Gp between the electromagnetic coil 43 and the armature 44, the degree of reduction of the gap Gp is calculated. Therefore, it becomes possible to shorten the injection time according to the degree of reduction thus obtained, and consequently to correct the reduction of the amount of fuel injected from the valve 2. Therefore, the unnecessary increase in the amount of fuel injected from the fuel injection valve 2 can be suitably compensated, and the amount of fuel can be controlled more accurately when the engine 1 is cold started. Become.

(2) In the present embodiment, the target injection amount Qt is reduced as the elapsed time after the starting operation of the engine 1 is shorter and the estimated temperature of the fuel injection valve 2 is lower. As a result, the injection time can be shortened depending on the temperature characteristics of the fuel injection valve 2, and an unnecessary increase in the amount of fuel injected from the valve 2 can be suitably compensated. Become.

(3) Further, in the present embodiment, the target injection amount Qt is reduced and corrected only during a predetermined period from the completion of the start of the engine until the temperatures of the respective parts of the fuel injection valve 2 become substantially uniform. I did it. Therefore, the injection time can be shortened only during the period in which the gap Gp may be temporarily reduced, and the cold start correction process can be efficiently executed.

(4) Further, in the present embodiment, the correction of the target injection amount Qt described above is performed by the fuel of the in-cylinder injection type internal combustion engine for directly injecting the fuel injected from the fuel injection valve 2 into the cylinder. It is designed to be executed by the injection control device. Generally, in a cylinder injection internal combustion engine, since it is necessary to directly inject and supply fuel into a cylinder in which the internal pressure is increased, the fuel is accumulated in the fuel injection valve at an extremely high pressure. It is being supplied. For this reason, when the gap Gp is temporarily reduced, the amount of increase in the amount of fuel injected from the fuel injection valve 2 associated therewith also becomes extremely large. On the other hand, according to the present embodiment, in such an in-cylinder injection type internal combustion engine, the fuel injection valve 2
It becomes possible to suitably compensate for an unnecessary increase in the amount of fuel injected from.

(5) In particular, in the present embodiment, the above-described reduction correction of the target injection amount Qt is executed by the fuel injection control device of the common rail type diesel engine 1. Among the cylinder injection type internal combustion engines, the common rail type diesel engine has an extremely high injection pressure because the cylinder pressure in the combustion stroke is extremely high. Therefore, when the gap Gp becomes temporarily small, the amount of increase in the amount of fuel injected from the fuel injection valve 2 becomes extremely large, and the in-cylinder pressure resulting from this increases excessively. There is also a great concern about an increase and eventually a decrease in the durability of the engine 1. On the contrary,
According to the present embodiment, in such a common rail type diesel engine 1, it is possible to preferably suppress an unnecessary rise in the cylinder pressure that may affect the durability thereof.

The above embodiment may be modified and implemented as follows. In the above-described embodiment, the predetermined temperature T2 may be set as a value that makes it possible to determine through (condition b) that an excessive increase in cylinder pressure may occur. Here, as is well known, in an internal combustion engine, the lower the intake air temperature THA, the higher the efficiency of filling air into the cylinder, and the higher the cylinder pressure in the compression stroke. Therefore, the lower the intake air temperature THA, the more likely the cylinder pressure will increase excessively.
In this respect, according to the above configuration, it is possible to execute the above-described low temperature start correction process only during the period in which the cylinder pressure is likely to be excessively increased.

Further, in order to suppress an excessive increase in the cylinder pressure, a sensor for detecting the cylinder pressure is separately provided, and the target injection amount is limited only when the cylinder pressure exceeds a predetermined pressure. It is also possible to adopt a configuration in which Qt is reduced and corrected.

In the above embodiment, the target injection amount Qt is reduced and the injection time is shortened, but instead of this, the reference injection pressure may be reduced and corrected.
As is also well known, when the pressure (injection pressure) of the fuel supplied to the fuel injection valve is reduced, the amount of fuel injected from the valve decreases. Therefore, by correcting the reference injection pressure in accordance with the degree of reduction of the gap Gp, it is possible to suitably compensate for an unnecessary increase in the amount of fuel injected from the fuel injection valve 2, and thus the engine 1 It becomes possible to more accurately control the same fuel amount at the time of low temperature starting. In addition, the decompression correction amount for the reference injection pressure, the shorter the elapsed time after the starting operation of the engine 1,
Moreover, the lower the estimated temperature of the fuel injection valve 2, the higher the temperature.

Further, instead of correcting the target injection amount Qt by reducing the amount or correcting the reference injection pressure by reducing the amount, the fuel injection timing may be corrected by retarding. It is also well known that when the injection timing of the fuel injected from the fuel injection valve is retarded, the peak value of the in-cylinder pressure in the internal combustion engine decreases. Therefore, by correcting the injection timing in accordance with the degree of reduction of the gap Gp, it is possible to suitably suppress at least an unnecessary increase in the cylinder pressure due to the temporary reduction of the gap Gp. become.

On the other hand, as described above, the gap Gp
The temporary contraction of the armature 44 occurs because the lift speed and the lift timing of the armature 44 temporarily increase. That is, when the gap Gp is temporarily reduced, the injection timing is unnecessarily advanced. On the contrary,
According to the above-mentioned configuration in which the injection timing is retarded according to the degree of reduction of the gap Gp, it becomes possible to suitably compensate for such an unnecessary advance of the injection timing.

Incidentally, the increase width in the unnecessary increase in the cylinder pressure and the advance width in the unnecessary advancement of the injection timing become shorter as the elapsed time after the starting operation of the engine 1 becomes shorter.
Further, the lower the temperature of the fuel injection valve 2, the greater the value. Therefore, the shorter the elapsed time after the starting operation of the engine 1 is and the lower the estimated temperature of the fuel injection valve 2 is, the larger the retard correction amount of the injection timing may be made. As a result, it becomes possible to retard the injection timing according to the increase width of the cylinder internal pressure and the advance width of the injection timing at any given time, and unnecessary increase of the cylinder internal pressure or unnecessary injection timing can be achieved. It becomes possible to favorably compensate for the early stage.

Any one of the above-mentioned injection time shortening correction, injection pressure decompression correction, and injection timing retard correction 2
It is also possible to execute a combination of two or all of them. In short, the above gap Gp
It suffices that the change in the fuel injection mode such as the injection amount, the injection timing, or the injection pressure caused by the temporary reduction of the fuel injection amount can be appropriately compensated.

In the above embodiment, the temperature of the fuel injection valve 2 is estimated based on the intake air temperature THA. The engine parameter used for this estimation is the intake air temperature TH.
Not limited to A, for example, the cooling water temperature THW, the fuel injection valve 2
Any engine parameter that appropriately reflects the temperature can be appropriately adopted. Further, if there is a margin in space or cost, instead of estimating the temperature of the fuel injection valve 2 based on such engine parameters, a new sensor is provided to directly measure the temperature of each part of the valve 2. Of course, it is possible to measure.

In the above embodiment, the fuel injection control device according to the present invention is used in the common rail type diesel engine 1
I applied it to. Not limited to this, the fuel injection control device according to the present invention can be applied to other types of diesel engines, in-cylinder injection gasoline engines, intake port injection gasoline engines, and the like.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a fuel injection control device for an internal combustion engine according to the present invention.

FIG. 2 is a schematic diagram showing a map structure of a map used for calculating a correction coefficient.

FIG. 3 is a flowchart showing a processing procedure of processing for calculating an injection time.

FIG. 4 is a timing chart showing an example of the transition of the correction mode of the target injection amount according to the same embodiment.

FIG. 5 is a front sectional view showing a front sectional structure of the fuel injection valve.

FIG. 6 is a graph showing the relationship between the gap and the suction force acting on the armature.

FIG. 7 is a graph showing an example of changes in the lift amount of the armature.

FIG. 8 is a graph showing an example of changes in fuel injection rate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Diesel engine, 2 ... Fuel injection valve, 4 ... Common rail, 5 ... Supply pipe, 6 ... Fuel pump, 6a ... Discharge port, 6b ... Suction port, 6c ... Return port, 7 ... Check valve, 8 ... Fuel tank , 9 ... Filter, 10 ... Pressure control valve, 11 ... Return piping, 12 ... Relief valve, 13 ... Intake passage, 15 ... Accelerator pedal, 21 ... Accelerator sensor, 22 ... Water temperature sensor, 23 ... Intake temperature sensor, 24 ... Combustion Temperature sensor, 25 ... Fuel pressure sensor, 26 ... Crank angle sensor, 27 ... Cam angle sensor, 28 ... Starter switch, 3
DESCRIPTION OF SYMBOLS 1 ... Intake valve, 32 ... Exhaust valve, 33 ... Electronic control device, 41
... needle, 42 ... spring, 43 ... electromagnetic coil, 44 ... armature, 45 ... spring, 46 ... case, 47 ... injection hole.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takehiro Tanaka             14 Iwatani Shimohakaku-cho, Nishio-shi, Aichi Stock Association             Company Japan Auto Parts Research Institute (72) Inventor Takeshi Sato             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Yukihisa Yamamoto             2-1, Toyota-cho, Kariya City, Aichi Stock Association             Inside Toyota Toyota Industries F-term (reference) 3G301 HA02 HA04 JA03 JA21 KA02                       LB11 LC01 MA11 MA18 NE06                       NE12 NE23 PA10Z PB01Z                       PB08Z PE04Z PE08Z PF03Z                       PF16Z

Claims (14)

[Claims] 1. An electromagnetically driven fuel injection valve, the fuel injection mode of which is determined by an armature lift operation based on energization of an electromagnetic coil, and an injection timing of fuel supplied to the fuel injection valve to an internal combustion engine and In a fuel injection control device for an internal combustion engine, the injection amount of which is controlled in accordance with the energization timing and energization time of the electromagnetic coil, the fuel resulting from a change in the gap between the electromagnetic coil and the armature during cold start of the engine. A fuel injection control device for an internal combustion engine, comprising a correction means for correcting a change in an injection mode. 2. The fuel injection valve is opened in response to a lift operation in a direction in which the armature is attracted to the electromagnetic coil side by energizing the electromagnetic coil, and the correction means includes: The fuel injection control device for an internal combustion engine according to claim 1, wherein the amount of fuel injected from the fuel injection valve is reduced and corrected based on the elapsed time after the starting operation of the engine and the estimated temperature of the fuel injection valve. . 3. The correction means for reducing the amount of fuel injected from the fuel injection valve as the elapsed time after the engine starting operation is shorter and the estimated temperature of the fuel injection valve is lower. 3. The fuel injection control device for an internal combustion engine according to claim 2, wherein 4. The fuel injection valve is opened in response to a lift operation in a direction in which the armature is attracted to the electromagnetic coil side by energizing the electromagnetic coil, and the correction means includes: The fuel injection control of an internal combustion engine according to claim 1, wherein the pressure of the fuel supplied to the fuel injection valve is corrected based on the elapsed time after the starting operation of the engine and the estimated temperature of the fuel injection valve. apparatus. 5. The correction means reduces the pressure of fuel supplied to the fuel injection valve as the elapsed time after the engine starting operation is shorter and the estimated temperature of the fuel injection valve is lower. The fuel injection control device for an internal combustion engine according to claim 4, wherein the amount is large. 6. The fuel injection valve is opened in response to a lift operation in a direction in which the armature is attracted toward the electromagnetic coil due to energization of the electromagnetic coil, and the correction means includes: The fuel for an internal combustion engine according to claim 1, wherein the injection timing of the fuel injected from the fuel injection valve is retarded on the basis of the elapsed time after the starting operation of the engine and the estimated temperature of the fuel injection valve. Injection control device. 7. The correction means delays the injection timing of the fuel injected from the fuel injection valve as the elapsed time after the starting operation of the engine is shorter and the estimated temperature of the fuel injection valve is lower. The fuel injection control device for an internal combustion engine according to claim 6, wherein the angle correction amount is large. 8. The fuel injection valve is opened in response to a lift operation in a direction in which the armature is attracted to the electromagnetic coil side due to energization of the electromagnetic coil, and the correction means includes: Based on the elapsed time after the starting operation of the engine and the estimated temperature of the fuel injection valve, a reduction correction of the amount of fuel injected from the fuel injection valve and a reduction of the pressure of the fuel supplied to the fuel injection valve are performed. The fuel injection control device for an internal combustion engine according to claim 1, wherein at least one of correction and retard correction of an injection timing of fuel injected from the fuel injection valve is executed. 9. The correction means reduces the amount of fuel injected from the fuel injection valve as the elapsed time after the engine starting operation is shorter and the estimated temperature of the fuel injection valve is lower. The correction amount is set large, and the pressure reduction correction amount of the fuel supplied to the fuel injection valve is set large.
9. The fuel injection control device for an internal combustion engine according to claim 8, wherein the retard correction amount is set large with respect to the injection timing of the fuel injected from the fuel injection valve. 10. The correction means estimates the temperature of the fuel injection valve based on the cooling water temperature of the engine.
10. A fuel injection control device for an internal combustion engine according to any one of 9 above. 11. The fuel injection control device for an internal combustion engine according to claim 2, wherein the correction means estimates the temperature of the fuel injection valve based on the temperature of the air sucked into the engine. 12. The correction means executes the correction only during a predetermined period from the completion of the start of the engine to the temperature of each part of the fuel injection valve becoming substantially uniform.
11. A fuel injection control device for an internal combustion engine according to any one of 1 to 11. 13. A fuel injection control device for an internal combustion engine according to any one of claims 1 to 12, wherein the engine comprises means for accumulating fuel supplied to the fuel injection valve, and the fuel injection valve. A fuel injection control device for an internal combustion engine, which is an in-cylinder injection type internal combustion engine that directly injects fuel injected from a cylinder. 14. The fuel injection control device for an internal combustion engine according to claim 13, wherein the internal combustion engine is a common rail type diesel engine.