JP4276401B2 - Fuel injection control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND 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]
[Prior art]
For example, in this type of fuel injection control device employed in a common rail type diesel engine, various control amounts such as injection timing and injection time are determined based on the engine operating state when controlling fuel injection. The fuel injection valve is driven and controlled based on the controlled amount. Thus, basically, an amount of fuel suitable for the engine operating state is injected and supplied to the internal combustion engine, and the operation of the engine is also properly maintained.
[0003]
However, as is well known, fuel usually decreases in bulk modulus and viscosity as its temperature increases. This causes a decrease in 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.
[0004]
Therefore, even when the fuel injection valve is driven to open for the same time, different amounts of fuel are injected and supplied from the fuel injection valve to the internal combustion engine depending on whether the fuel temperature is high or low. As a result, an unnecessary change in the cylinder pressure of the internal combustion engine is caused. This causes inconveniences such as a decrease in the durability of the internal combustion engine due to an excessive increase in the cylinder pressure and an unstable engine output.
[0005]
Therefore, conventionally, for example, as disclosed in Japanese Patent Application Laid-Open No. 9-60542, the fuel temperature is detected, and the opening time of the fuel injection valve, that is, the injection time (injection amount) is corrected according to the detected fuel temperature. A device that performs the above has also been proposed. By performing such correction processing, 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 the above-described unnecessary change in the cylinder pressure can be suppressed. It becomes like this.
[0006]
[Problems to be solved by the invention]
As shown in FIG. 5, the electromagnetically driven fuel injection valve is usually a needle 41 that is a valve body, a spring 42 that urges the needle 41 in the valve closing direction, an electromagnetic coil 43, and an armature 44. And a spring 45 that urges the armature 44 in a direction in which the armature 44 is separated from the electromagnetic coil 43 is housed integrally in the case 46. Further, in the case 46, there are provided fuel passages connected to a fuel pressure accumulation pipe (common rail) and a return pipe to the fuel tank, respectively, including an injection hole 47 for injecting fuel to the cylinder of the internal combustion engine. It has been.
[0007]
When the fuel injection valve is driven to open, the armature 44 is moved in a direction against the urging force of the spring 45, that is, in a direction of suction toward the electromagnetic coil 43, by energizing the electromagnetic coil 43. As a result, the pressure balance between the fuel passages connected to the common rail and the return pipe changes, and accordingly, the needle 41 is moved in a direction that allows communication between the nozzle hole 47 and the common rail. That is, fuel injection from the injection hole 47 is started.
[0008]
On the other hand, energization of the electromagnetic coil 43 is stopped when the fuel injection valve is driven to close. As a result, the armature 44 is moved to the position shown in FIG. 5 by the biasing force of the spring 42. At this time, since the fuel passages are also blocked and the pressure balance is maintained, the needle 41 is moved in a direction to block the communication between the nozzle hole 47 and the common rail by the biasing force of the spring 42. That is, fuel injection from the injection hole 47 is stopped.
[0009]
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 attractive force is accurately transmitted through the electromagnetic coil 43. It is desirable to control well. However, the attraction force acting on the armature 44 is unnecessarily increased in a very short period immediately after the engine is cold started even if the amount of current supplied to the electromagnetic coil 43 is constant. Have been confirmed.
[0010]
Hereinafter, the reason will be described with reference to FIGS.
Normally, when the operation of the internal combustion engine is started, the armature 44 starts sliding in the fuel injection valve, and frictional heat is generated on the sliding surface. Here, since the volume of the armature 44 is extremely small compared to 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 increases. After that, when the drive control of the fuel injection valve is continued, the temperature of the case 46 gradually increases, and accordingly, the temperature difference gradually decreases. In other words, paying attention to a very short period immediately after the engine is started at a low temperature, a large difference occurs in the thermal expansion amount between the armature 44 and the case 46.
[0011]
Depending on the fuel injection valve, the gap Gp between the electromagnetic coil 43 and the armature 44 in the valve open state is temporarily reduced due to such a difference in thermal expansion amount. That is, as shown in FIG. 6, the relationship between the gap Gp and the attractive force acting on the armature 44, even when the electromagnetic force generated by the electromagnetic coil 43 is constant, The suction force acting on the armature 44 is increased.
[0012]
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 when starting fuel injection, the gap Gp is 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) where the armature 44 is not small. As a result, as shown in FIG. 8, the fuel injection rate is higher when the gap Gp indicated by the alternate long and short dash line in FIG. 8 is smaller than the steady-state fuel injection rate indicated by the solid line. For example, an unnecessary increase in the fuel injection amount is caused.
[0013]
In addition, the total amount of magnetic flux acting on the armature 44 in one fuel injection increases as the lift speed and the lift timing of the armature 44 in the valve opening direction become earlier. That is, the magnetic flux remaining in the magnetic circuit when energization to the electromagnetic coil 43 is stopped increases. For this reason, even after the energization of the electromagnetic coil 43 is stopped, the decrease of the magnetic flux acting on the armature 44 is prolonged, and the lift speed and the lift timing of the armature 44 in the valve closing direction are also delayed (see FIG. 7). As a result, the decrease in the fuel injection rate is also delayed by that amount (see FIG. 8), and an unnecessary increase in the fuel injection amount is unavoidable.
[0014]
In addition, 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 pressure of the internal combustion engine, and if this becomes excessive, the durability of the internal combustion engine is also affected. It will be affected.
[0015]
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 the fuel injection amount based on the estimated temperature of each part. It is also conceivable to compensate for the above-described unnecessary increase in the fuel injection amount by correcting the amount to decrease. However, the reduction in the gap Gp between the electromagnetic coil 43 and the armature 44 described above occurs only in a very short period immediately after the engine cold start, whereas the fuel temperature changes almost within such a period. do not do. For this reason, when the fuel injection amount reduction correction is simply performed based on the fuel temperature, the above problem cannot be solved.
[0016]
The present invention has been made in view of such circumstances, and an object of the present invention is to more accurately control the fuel injection mode at the time of cold start of an internal combustion engine including an electromagnetically driven fuel injection valve. An object of the present invention is to provide a fuel injection control device for an internal combustion engine.
[0017]
[Means for Solving the Problems]
In the following, means for achieving the above object and its effects are described.
First, the invention according to claim 1 includes an electromagnetically driven fuel injection valve that 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, In a fuel injection control device for an internal combustion engine in which an injection timing and an injection amount of fuel supplied to a fuel injection valve are controlled in accordance with an energization timing and energization time of the electromagnetic coil, the engine is started at a low temperature Occurs in the predetermined period immediately after Gap between the electromagnetic coil and the armature Temporarily shrink caused by Increase in the injection amount 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 amount of reduction correction of the fuel amount injected from the fuel injection valve is increased. To Correction is performed during the predetermined period The gist is to provide a correcting means.
[0018]
According to the above configuration, when the engine is started at a low temperature, in other words, when the temperature of the fuel injection valve is low, the engine is started, so that the gap between the electromagnetic coil and the armature is temporarily increased. Shrink Even if you want to Shrink It becomes possible to correct the change in the fuel injection mode accompanying the. Therefore, the fuel injection mode at the time of low-temperature start can be controlled more accurately for the internal combustion engine including the electromagnetically driven fuel injection valve.
[0020]
Also According to the above configuration, when the amount of fuel injected from the fuel injection valve unnecessarily increases as the gap between the electromagnetic coil and the armature temporarily decreases, the elapsed time after the engine start operation and the fuel injection valve Based on the estimated temperature, a reduction degree of the gap can be obtained, and the fuel amount can be corrected for reduction according to the obtained reduction degree. Therefore, an unnecessary increase in the amount of fuel injected from the fuel injection valve can be suitably compensated.
[0022]
here The above-described degree of reduction of the gap, and hence the increase in 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 regard, according to the above-described configuration, it is possible to perform a decrease correction for the fuel amount in accordance with such a tendency, and it is possible to appropriately compensate for the unnecessary increase.
[0023]
The invention according to claim 2 includes an electromagnetically driven fuel injection valve that is opened in response to a lift operation in a direction in which the armature is attracted toward the electromagnetic coil by energizing the electromagnetic coil, In a fuel injection control device for an internal combustion engine in which an injection timing and an injection amount of fuel supplied to a fuel injection valve are controlled in accordance with an energization timing and energization time of the electromagnetic coil, the engine is started at a low temperature Occurs in the predetermined period immediately after Gap between the electromagnetic coil and the armature Temporarily shrink caused by Increase in the injection amount 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 pressure reduction correction amount of the pressure of the fuel supplied to the fuel injection valve is reduced. Make big Correction is performed during the predetermined period The gist of the invention is that it comprises a correcting means.
[0025]
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, the injection pressure is corrected by reducing the injection pressure according to the reduction degree of the gap. , Contract Claim 2 According to the invention described in claim 1 Effects similar to those of the invention described in Gain Be able to.
[0026]
The invention according to claim 3 includes an electromagnetically driven fuel injection valve that 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, In a fuel injection control device for an internal combustion engine in which an injection timing and an injection amount of fuel supplied to a fuel injection valve are controlled in accordance with an energization timing and energization time of the electromagnetic coil, the engine is started at a low temperature Occurs in the predetermined period immediately after Gap between the electromagnetic coil and the armature Temporarily shrink caused by Increase in cylinder pressure due to increase in injection amount 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 delay correction of the injection timing of the fuel injected from the fuel injection valve Increase the amount Correction is performed during the predetermined period The gist of the invention is that it comprises a correcting means.
[0027]
As is well known, when the injection timing of the fuel injected from the fuel injection valve is retarded, the peak value of the cylinder pressure in the internal combustion engine decreases. Therefore, according to the above configuration, at least an unnecessary increase in the in-cylinder pressure due to the temporary reduction of the gap is suitably suppressed by correcting the delay of the injection timing according to the degree of reduction of the gap. Will be able to.
[0029]
In addition, When the in-cylinder pressure increases as the gap is temporarily reduced, the degree of increase is greater as the elapsed time after the engine start 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 correct the retard of the injection timing according to such a tendency, and it is possible to suitably compensate for an unnecessary increase in the cylinder pressure.
[0030]
According to a fourth aspect of the present invention, there is provided an electromagnetically driven fuel injection valve that 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, In a fuel injection control device for an internal combustion engine in which an injection timing and an injection amount of fuel supplied to a fuel injection valve are controlled in accordance with an energization timing and energization time of the electromagnetic coil, the engine is started at a low temperature Occurs in the predetermined period immediately after Gap between the electromagnetic coil and the armature Temporarily shrink caused by Of the increase in the injection amount and the increase in the cylinder pressure due to the increase in the injection amount, at least the increase in the cylinder pressure Based on the elapsed time after the start operation of the engine and the estimated temperature of the fuel injection valve, the amount of fuel injected from the fuel injection valve is corrected, and the fuel injection valve Performing at least one of a pressure reduction correction of the pressure of the supplied fuel and a delay correction of the injection timing of the fuel injected from the fuel injection valve, and the shorter the elapsed time after the start operation of the engine, and The lower the estimated temperature of the fuel injection valve, the larger the reduction correction amount for the amount of fuel injected from the fuel injection valve. Corrections to be made during the predetermined period As for the pressure of the fuel supplied to the fuel injection valve, the decompression correction amount is set large. Corrections to be made during the predetermined period The delay correction amount is increased for the injection timing of the fuel injected from the fuel injection valve. Correction is performed during the predetermined period The gist of the invention is that it comprises a correcting means.
[0032]
Claim 4 According to the invention described in, both the unnecessary increase in the amount of fuel injected from the fuel injection valve and the unnecessary increase in the cylinder pressure accompanying the temporary reduction of the gap, or at least the cylinder pressure is unnecessary. Therefore, it is possible to suitably compensate for the increase.
[0033]
Note that when estimating the temperature of the fuel injection valve, the temperature is estimated based on engine parameters in which the temperature is preferably reflected, that is, for example, claims 5 According to the configuration, such as estimating based on the cooling water temperature of the engine 6 As described above, a configuration in which estimation is performed based on the temperature of air taken into the engine can be employed. Both the cooling water temperature and the intake air temperature can be measured by a sensor normally provided in the internal combustion engine, and no new sensor is required for estimating the temperature of the fuel injection valve. Of course, a sensor or the like that directly measures the temperature of each part of the fuel injection valve may be provided if there is room or cost.
[0034]
Claims 7 The invention described in claim 1 6 In the fuel injection control device for an internal combustion engine according to any one of the above, the correction means is limited to a predetermined period from when the start of the engine is completed until the temperature of each part of the fuel injection valve becomes substantially uniform. The gist is to execute the correction.
[0035]
According to the above configuration, the correction for the change in the fuel injection mode is executed only during a period in which the gap may be temporarily reduced, so that more accurate correction in accordance with the actual situation is realized. Become.
[0036]
Claims 8 The invention described in claim 1 7 The fuel injection control device for an internal combustion engine according to any one of the above, wherein the engine includes means for stocking the fuel supplied to the fuel injection valve, and the fuel injected from the fuel injection valve directly into the cylinder The gist of the invention is that it is an in-cylinder injection type internal combustion engine.
[0037]
Usually, in an in-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. Therefore, the fuel is accumulated in the fuel injection valve at an extremely high pressure. Supplied at. For this reason, when the gap is temporarily reduced and the armature lift speed or lift timing changes, an error in the amount of fuel injected from the fuel injection valve becomes noticeable. In this regard, 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.
[0038]
Claims 9 The invention described in claim 8 In the fuel injection control device for an internal combustion engine described above, the gist is that the internal combustion engine is a common rail type diesel engine.
[0039]
Among the in-cylinder injection type internal combustion engines, the common rail type diesel engine has a very high pressure in the cylinder during the combustion stroke, and therefore the injection pressure is set to be extremely high. For this reason, when the gap is temporarily reduced, an error in the amount of fuel injected from the fuel injection valve becomes significant, and the durability of the engine when the in-cylinder pressure rises accordingly is increased. Concerns about the decline also increase. In this regard, according to the above configuration, in such a common rail type diesel engine, it is possible to suitably suppress an unnecessary increase in the cylinder pressure that may affect the durability of the diesel engine. .
[0040]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a combustion injection control device for an internal combustion engine according to the present invention will be described with reference to FIGS.
[0041]
FIG. 1 shows a schematic configuration of a fuel injection control device for an internal combustion engine according to the present embodiment, more specifically, a system related to fuel injection of a pressure accumulation type (common rail type) diesel engine mounted on a vehicle.
[0042]
As shown in FIG. 1, the diesel engine 1 is provided with a plurality of cylinders (four cylinders in the present embodiment) # 1 to # 4, and the combustion chambers of the cylinders # 1 to # 4 are provided. An electromagnetically driven fuel injection valve 2 for injecting fuel is disposed. Fuel injection from the fuel injection valve 2 to each cylinder # 1 to # 4 of the engine 1 is controlled by switching between energization of the electromagnetic coil 43 provided in the valve 2 and interruption of the energization. In addition, as this fuel injection valve 2, the fuel injection valve which has the structure illustrated in previous FIG. 5 is assumed.
[0043]
The fuel injection valve 2 is connected to a common rail 4 serving as a pressure accumulating pipe common to each cylinder, and while the electromagnetic coil 43 is energized, that is, while the valve is driven to open, The fuel is injected from the fuel injection valve 2 into each cylinder # 1 to # 4 of the engine 1. The common rail 4 continuously accumulates fuel at a pressure high enough to enable such fuel injection.
[0044]
The common rail 4 is connected to the discharge port 6 a of the fuel pump 6 through the supply pipe 5. A check valve 7 is provided in the middle of the supply pipe 5. The check valve 7 allows fuel to be supplied from the fuel pump 6 to the common rail 4 and restricts the backflow of fuel from the common rail 4 to the fuel pump 6.
[0045]
The fuel pump 6 is connected to the fuel tank 8 through the suction port 6b, and a filter 9 is provided in the middle thereof. The fuel pump 6 is driven by reciprocating a plunger by a cam (not shown) synchronized with the rotation of the engine 1. As a result, the fuel pump 6 draws 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.
[0046]
Further, a pressure control valve 10 is provided in the vicinity of the discharge port 6 a of the fuel pump 6. The pressure control valve 10 closes its valve body in response to the ON signal, and allows the supply of fuel from the discharge port 6a toward the common rail 4. The pressure control valve 10 opens its valve body in response to the off signal, and surplus fuel that is 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 return to the tank 8. The fuel pressure (and hence 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.
[0047]
The common rail 4 is provided with a relief valve 12, 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.
[0048]
The engine 1 is provided with the following various sensors and the like in order to detect the state. That is, an accelerator sensor 21 for detecting the depression amount (accelerator opening) ACC is provided in the vicinity of the accelerator pedal 15.
[0049]
Further, the cylinder block of the engine 1 is provided with a water temperature sensor 22 for detecting the temperature THW of the cooling water.
In addition, an intake air temperature sensor 23 for detecting the temperature THA of the air taken into the engine 1 is provided in the vicinity of an air cleaner (not shown) provided upstream of the intake passage 13 of the engine 1.
[0050]
In addition, the return pipe 11 has a fuel temperature sensor 24 for detecting the fuel temperature THF, and the common rail 4 has a fuel pressure sensor for detecting the pressure (and hence the injection pressure) PF of the fuel in the common rail 4. 25 are provided.
[0051]
In the present embodiment, a crank angle sensor 26 is provided in the vicinity of a pulsar provided on a crankshaft (not shown) of the engine 1. Further, the rotation of the crankshaft is transmitted to a camshaft (not shown) for opening / closing the intake valve 31 and the exhaust valve 32 via a timing belt or the like.
[0052]
The camshaft is set to rotate at a rotational speed that is 1/2 of the crankshaft. A cam angle sensor 27 is provided in the vicinity of the pulsar provided on the camshaft. In the present embodiment, the engine rotational 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 cylinder # 1 to # 4 is calculated. (Cylinder is discriminated).
[0053]
The engine 1 is provided with a starter (not shown) for starting the engine 1. This starter is provided with a starter switch 28 for detecting its operating state. The starter switch 28 is operated when an ignition switch (not shown) is operated from the OFF position to the start position by the driver when the engine 1 is started, and the starter is in operation (when in the cranking state). The signal ST is output as “ON”. Further, the starter switch 28 generates a starter signal ST when the start of the engine 1 is completed (in an autonomous operation state) or when the start of the engine 1 fails and the ignition switch is returned from the start position to the ON position. Output as “Off”.
[0054]
In the present embodiment, an electronic control device 33 is provided for managing various controls of the engine 1. The electronic control device 33 takes in output signals from 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, and the like. . 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 that are grasped based on these output signals.
[0055]
Hereinafter, the outline of the fuel injection control according to the present embodiment will be described.
The electronic control unit 33 performs fuel injection control from the fuel injection valve 2 as part of the various controls. This fuel injection control is performed as follows.
[0056]
That is, first, the electronic control unit 33 calculates the fuel injection amount (“final injection amount Qf”) and the fuel injection timing according to the operating state of the engine 1. Then, the injection time required for the injection of the amount corresponding to the calculated final injection amount Qf is calculated according to the engine rotational speed NE and the injection pressure PF at that time.
[0057]
When the fuel injection timing calculated here is reached, the electronic control unit 33 starts energization of the electromagnetic coil 43 of the fuel injection valve 2 and each cylinder # 1 to # 4 of the high-pressure fuel supplied from the common rail 4 is started. Start injection into Thereafter, the energization to the electromagnetic coil 43 is maintained for the calculated injection time and a necessary amount of fuel is injected, and then the energization to the electromagnetic coil 43 is interrupted to end the fuel injection.
[0058]
In addition, the electronic control unit 33 performs such fuel injection control while also controlling the pressure (injection pressure) of fuel accumulated in the common rail 4. This injection pressure control is performed as follows.
[0059]
That is, first, the electronic control unit 33 calculates a reference injection pressure that 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 controls the pressure control valve 10 and the relief valve 12 to adjust the fuel pressure PF in the common rail 4 so as to hold the calculated reference injection pressure.
[0060]
Here, as described above, in the engine 1, a temperature difference is generated between the case 46 and the armature 44 of the fuel injection valve 2 in a very short period immediately after the low temperature start, and accordingly, the electromagnetic coil 43 and the armature 44. The gap Gp (FIG. 5) between these is temporarily reduced. In addition, as described above, the amount of fuel injected from the fuel injection valve 2 unnecessarily increases due to this.
[0061]
The inventors have confirmed that the degree of such temporary reduction of the gap Gp changes according to the elapsed time after the start 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 temperature difference is larger and the gap Gp is smaller as the temperature of the fuel injection valve 2 is lower. Further, when the drive control of the engine 1, and hence the fuel injection valve 2, is continued, the temperature difference gradually decreases accordingly, and the temporary reduction of the gap Gp is also eliminated.
[0062]
Therefore, in the present embodiment, paying attention to such a change tendency of the gap Gp, the final injection amount Qf is reduced and corrected based on the elapsed time after the start operation of the engine 1 and the estimated temperature of the fuel injection valve 2. An unnecessary increase in the amount of fuel injected from the valve 2 is compensated. In the present 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 temperature is favorably reflected, is substituted.
[0063]
Specifically, as a tendency of the correction, as shown in FIG. 2, a map used for calculating the correction coefficient K1 calculated at the time of correction, the lower the intake air temperature THA and the shorter the elapsed time after the engine start, The correction coefficient K1 is calculated as a large value. The correction coefficient K1 is calculated as a number equal to or greater than “1”.
[0064]
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 injection time is calculated based on the calculated target injection amount Qt. Yes.
Target injection amount Qt ← Qf × (1 / K1) (1)
Accordingly, the target injection amount Qt is reduced (injection time is shortened) as the correction coefficient K1 is calculated as a large value, and the fuel amount injected from the fuel injection valve 2 is reduced. An unnecessary increase caused by the temporary reduction of the gap Gp is compensated.
[0065]
Hereinafter, the detailed processing procedure of the calculation process of the injection time including the correction process at the time of low temperature start of the engine 1 will be described with reference to the flowchart shown in FIG. The series of processing shown in this flowchart is repeatedly executed by the electronic control device 33 with a predetermined control cycle. Further, this processing is executed only after the engine 1 is in an autonomous operation state, that is, after the start is completed.
[0066]
In this process, first, the engine parameters ACC, THW, THA, THF, PF, NE, ST are detected through the sensors 21 to 27 and the starter switch 28 (step S100). Then, after determining the operating state of the engine 1 based on these engine parameters, 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).
[0067]
Then, the low temperature start correction process is executed (steps S102 to S105).
In this process, first, it is determined whether or not all of the following (condition a) to (condition c) are satisfied (step S102).
(Condition a): The coolant temperature THW is lower than a predetermined temperature T1 (for example, 0 ° C.).
(Condition b): The intake air temperature THA is lower than a 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 “ON” is less than a predetermined time C (for example, 5 minutes).
[0068]
Each of the predetermined temperatures T1 and T2 and the predetermined time C is a predetermined period from the completion of the engine start until the temperature of each part of the fuel injection valve becomes substantially uniform (conditions a) to (conditions). The value that can be determined through c) is determined in advance after being obtained through experiments or the like. Specifically, when all of these (Conditions a) to (Condition c) are satisfied, the gap Gp is temporarily reduced, and as a result, an 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 inviting.
[0069]
Then, when all of these (condition a) to (condition c) are satisfied (step S102: YES), the amount of fuel injected from the fuel injection valve 2 may increase unnecessarily, as described above. Then, the correction coefficient K1 is calculated based on the map shown in FIG. 2 (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 start. The relationship between the intake air temperature THA, the elapsed time after the engine start and the correction coefficient K1 is experimentally determined. After being obtained, it is stored in advance in an appropriate memory of the electronic control unit 33.
[0070]
On the other hand, if any one of the above (conditions a) to (condition c) is not satisfied (step S102: NO), the amount of fuel injected from the fuel injection valve 2 is not likely to increase unnecessarily. The correction coefficient K1 is set to “1” (step S104).
[0071]
After the correction coefficient K1 is calculated or set in this way, the target injection amount Qt is calculated from the above equation (1) based on the correction coefficient K1 and the final injection amount Qf (step S105).
[0072]
After that, based on the engine rotational speed NE and the injection pressure PF, an injection time required for injecting and supplying an amount of fuel corresponding to the target injection amount Qt to the engine 1 is calculated (step S106). ).
[0073]
Hereinafter, how the fuel injection control described above is performed will be described with reference to a timing chart shown in FIG.
FIG. 4 shows an example of a change in the correction amount with respect to 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-up increase processing is also performed. This post-startup increase process is a process executed to stabilize the engine speed NE immediately after the engine 1 reaches the complete explosion state. The correction coefficient K2 for the target injection amount Qt is based on the coolant temperature THW. Is set. Specifically, the correction coefficient K2 is calculated as a larger value as the cooling water temperature THW is lower. The correction coefficient K2 is calculated as a number greater than “1”. The target injection amount Qt is calculated from the following equation based on the final injection amount Qf and the correction coefficients K1 and K2.
Qt = Qf × (1 / K1) × K2
Now, when the start operation of the engine 1 is performed (timing t1), the low temperature start correction process and the post-start-up increase process described above are performed in a period until the engine 1 enters the autonomous operation state (timing t1 to t2). The target injection amount Qt that can be smoothly shifted to the autonomous operation state of the engine 1 is calculated through a separate process without being executed. Therefore, during this period, the correction amount for the target injection amount Qt is set to “0”.
[0074]
After that, when the engine 1 enters an autonomous operation state (timing t2), the low temperature start correction process and the post-startup increase process are both started. At this time, in the post-startup increase process, the correction coefficient K2 is calculated as a value that increases 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 correction coefficient K1 is calculated as a value for reducing the target injection amount Qt by the amount indicated by the arrow E in FIG. Accordingly, the correction amount for the target injection amount Qt at this time is an amount corresponding to a value obtained by multiplying the correction coefficients K1 and K2 (in this example, the correction amount is set to an amount on the side where the target injection amount Qt is reduced). ).
[0075]
Thereafter, when the operation of the engine 1 is continued (after timing t2), the coolant temperature THW gradually increases. Accordingly, as indicated by a one-dot chain line in FIG. 4, the correction coefficient K2 calculated by the post-startup increase process changes so as to gradually decrease the increase degree with respect to the target injection amount Qt. On the other hand, the correction coefficient K1 calculated by the low-temperature start correction process changes so as to gradually decrease the amount of reduction with respect to the target injection amount Qt. Then, the correction amount at this time changes corresponding to a value obtained by multiplying the correction coefficients K1 and K2 as indicated by a solid line in FIG. 4 (in this example, the target injection amount Qt is gradually increased). ).
[0076]
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 corrected by the correction coefficient K2 calculated by the post-startup increase process thereafter. It changes according to the change of. That is, the amount of increase with respect to the target injection amount Qt is gradually decreased (after timing t3).
[0077]
Thereafter, when the cooling water temperature THW rises sufficiently and the correction coefficient K1 calculated by the post-startup increase processing becomes “1” (timing t4), the correction amount becomes “0”.
[0078]
As described above, according to the present embodiment, the effects described below can be obtained.
(1) In the present embodiment, the target injection amount Qt is corrected to decrease based on the elapsed time after the start operation of the engine 1 and the estimated temperature of the fuel injection valve 2. As a result, when the amount of fuel injected from the fuel injection valve 2 unnecessarily increases as the gap Gp between the electromagnetic coil 43 and the armature 44 is temporarily reduced, the degree of reduction of the gap Gp is obtained. Accordingly, it is possible to shorten the injection time corresponding to the obtained degree of reduction, and thus to correct the amount of fuel injected from the valve 2. Accordingly, an unnecessary increase in the amount of fuel injected from the fuel injection valve 2 can be suitably compensated so that the amount of fuel can be more accurately controlled when the engine 1 is started at a low temperature. Become.
[0079]
(2) Further, in the present embodiment, the target injection amount Qt is reduced as the elapsed time after the start 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 according to 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.
[0080]
(3) Further, in the present embodiment, the target injection amount Qt is corrected to decrease only for a predetermined period after the start of the engine is completed until the temperature of each part of the fuel injection valve 2 becomes substantially uniform. . For this reason, the injection time can be shortened only during a period in which the gap Gp may be temporarily reduced, and the low-temperature start correction process can be executed efficiently.
[0081]
(4) Further, in the present embodiment, the fuel injection control device for the in-cylinder internal combustion engine that supplies the fuel injected from the fuel injection valve 2 directly into the cylinder for the above-described reduction correction of the target injection amount Qt. It was made to execute by. Here, normally, 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 supplied on the other hand. 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 is very large. On the other hand, according to the present embodiment, in such a direct injection internal combustion engine, an unnecessary increase in the amount of fuel injected from the fuel injection valve 2 can be suitably compensated. Become.
[0082]
(5) Particularly in the present embodiment, the reduction correction of the target injection amount Qt described above is executed by the fuel injection control device of the common rail type diesel engine 1. 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. 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 becomes extremely large, and an excessive increase in the in-cylinder pressure is caused. Concerns about the rise and, consequently, the decrease in the durability of the engine 1 also increase. On the other hand, according to the present embodiment, in such a common rail type diesel engine 1, it is possible to suitably suppress an unnecessary increase in the in-cylinder pressure that may affect the durability thereof. become.
[0083]
The embodiment described above may be modified as follows.
In the above embodiment, the predetermined temperature T2 may be set as a value that can be determined through (Condition b) that there is a risk of excessive increase in the cylinder pressure. Here, as is well known, in an internal combustion engine, the lower the intake air temperature THA, the higher the efficiency of charging air into the cylinder, and the cylinder pressure during the compression stroke increases. Therefore, as the intake air temperature THA is lower, the increase in the cylinder pressure tends to become excessive. In this regard, according to the above-described configuration, it is possible to execute the above-described low-temperature start correction process only during a period in which an excessive increase in the cylinder pressure is likely to occur.
[0084]
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 Qt is reduced only when the cylinder pressure exceeds a predetermined pressure. It is also possible to adopt a configuration for correcting.
[0085]
In the above embodiment, the target injection amount Qt is corrected to decrease and the injection time is shortened. Alternatively, the reference injection pressure may be corrected to reduce pressure. 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. Accordingly, by correcting the reference injection pressure to be reduced according to the degree of reduction of the gap Gp, an unnecessary increase in the amount of fuel injected from the fuel injection valve 2 can be suitably compensated, and consequently the engine 1 The amount of the fuel can be controlled more accurately during the cold start of the engine. Note that the pressure reduction correction amount for the reference injection pressure may be increased as the elapsed time after the start operation of the engine 1 is shorter and the estimated temperature of the fuel injection valve 2 is lower.
[0086]
In addition, instead of correcting the target injection amount Qt to decrease or correcting the reference injection pressure to be reduced, the fuel injection timing may be corrected to be retarded. 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 cylinder pressure in the internal combustion engine decreases. Accordingly, it is possible to suitably suppress at least an unnecessary increase in the in-cylinder pressure due to the temporary reduction of the gap Gp by correcting the delay of the injection timing in a manner corresponding to the degree of reduction of the gap Gp. become.
[0087]
On the other hand, as described above, the temporary reduction of the gap Gp is caused by temporarily increasing the lift speed and the lift timing of the armature 44. That is, when the gap Gp is temporarily reduced, the injection timing is unnecessarily advanced. On the other hand, according to the above-described configuration in which the injection timing is retarded in accordance with the degree of reduction of the gap Gp, it is possible to appropriately compensate for such unnecessary advancement of the injection timing.
[0088]
It should be noted that the increase width in the unnecessary increase in the cylinder pressure and the advance angle width in the unnecessary advance of the injection timing are shorter as the elapsed time after the start operation of the engine 1 is shorter and the temperature of the fuel injection valve 2 is lower. It ’s big. Therefore, the retard correction amount of the injection timing may be increased as the elapsed time after the start operation of the engine 1 is shorter and the estimated temperature of the fuel injection valve 2 is lower. As a result, it becomes possible to correct the delay of the injection timing in accordance with the range of increase in the cylinder pressure and the advance angle of the injection timing from time to time, and an unnecessary increase in the cylinder pressure and unnecessary injection timing can be achieved. It is possible to favorably compensate for the early advancement.
[0089]
Further, any two of the above-described correction for shortening the injection time, correction for reducing the injection pressure, and correction for retarding the injection timing may be executed in combination, or all of them may be executed together. In short, it is only necessary to suitably compensate for a change in the fuel injection mode such as the injection amount, the injection timing, or the injection pressure that occurs with the temporary reduction of the gap Gp.
[0090]
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 not limited to the intake air temperature THA, and any engine parameter that suitably reflects the temperature of the fuel injection valve 2, such as the coolant temperature THW, can be used as appropriate. In addition, if there is a space or cost margin, instead of estimating the temperature of the fuel injection valve 2 based on such engine parameters, the temperature of each part of the valve 2 is directly adjusted by providing a new sensor or the like. It is of course possible to measure.
[0091]
In the above embodiment, the fuel injection control device according to the present invention is applied to the common rail diesel engine 1. The fuel injection control device according to the present invention can be applied to other types of diesel engines, in-cylinder injection type gasoline engines, intake port injection type gasoline engines, and the like.
[Brief description of the 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 for processing for calculating an injection time.
FIG. 4 is a timing chart showing an example of a transition of a target injection amount correction mode according to the 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 attractive force acting on the armature.
FIG. 7 is a graph showing an example of the transition of the armature lift amount;
FIG. 8 is a graph showing an example of a change in fuel injection rate.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Diesel engine, 2 ... Fuel injection valve, 4 ... Common rail, 5 ... Supply piping, 6 ... Fuel pump, 6a ... Discharge port, 6b ... Intake 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 ... Fuel Temperature sensor, 25 ... Fuel pressure sensor, 26 ... Crank angle sensor, 27 ... Cam angle sensor, 28 ... Starter switch, 31 ... Intake valve, 32 ... Exhaust valve, 33 ... Electronic control unit, 41 ... Needle, 42 ... Spring, 43 ... Electromagnetic coil, 44 ... Armature, 45 ... Spring, 46 ... Case, 47 ... Injection hole.

Claims (9)

An internal combustion engine of fuel that is provided with an electromagnetically driven fuel injection valve that is opened in response to a lift operation in a direction in which the armature is attracted to the electromagnetic coil by energizing the electromagnetic coil, and is supplied to the fuel injection valve In the fuel injection control device for an internal combustion engine in which the injection timing and the injection amount are controlled according to the energization timing and energization time to the electromagnetic coil,
A means for correcting an increase in the injection amount caused by a temporary reduction in a gap between the electromagnetic coil and the armature that occurs in a predetermined period immediately after the engine is cold-started, and an elapsed time after the engine starting operation And a correction means for performing a correction for increasing the reduction correction amount of the amount of fuel injected from the fuel injection valve in the predetermined period as the estimated temperature of the fuel injection valve is lower and the estimated temperature of the fuel injection valve is lower. A fuel injection control device for an internal combustion engine. An internal combustion engine of fuel that is provided with an electromagnetically driven fuel injection valve that is opened in response to a lift operation in a direction in which the armature is attracted to the electromagnetic coil by energizing the electromagnetic coil, and is supplied to the fuel injection valve In the fuel injection control device for an internal combustion engine in which the injection timing and the injection amount are controlled according to the energization timing and energization time to the electromagnetic coil,
A means for correcting an increase in the injection amount caused by a temporary reduction in a gap between the electromagnetic coil and the armature that occurs in a predetermined period immediately after the engine is cold-started, and an elapsed time after the engine starting operation And a correction unit that performs correction for increasing the pressure reduction correction amount of the pressure of the fuel supplied to the fuel injection valve in the predetermined period as the estimated temperature of the fuel injection valve is lower. A fuel injection control device for an internal combustion engine. An internal combustion engine of fuel that is provided with an electromagnetically driven fuel injection valve that is opened in response to a lift operation in a direction in which the armature is attracted to the electromagnetic coil by energizing the electromagnetic coil, and is supplied to the fuel injection valve In the fuel injection control device for an internal combustion engine in which the injection timing and the injection amount are controlled according to the energization timing and energization time to the electromagnetic coil,
Means for correcting an increase in in- cylinder pressure due to an increase in the injection amount due to a temporary reduction in a gap between the electromagnetic coil and the armature that occurs in a predetermined period immediately after the engine is cold-started, A correction for increasing the retard correction amount of the injection timing of the fuel injected from the fuel injection valve as the elapsed time after the start operation is shorter and the estimated temperature of the fuel injection valve is lower is the predetermined period. A fuel injection control device for an internal combustion engine, comprising: a correction unit that performs the correction. An internal combustion engine of fuel that is provided with an electromagnetically driven fuel injection valve that is opened in response to a lift operation in a direction in which the armature is attracted to the electromagnetic coil by energizing the electromagnetic coil, and is supplied to the fuel injection valve In the fuel injection control device for an internal combustion engine in which the injection timing and the injection amount are controlled according to the energization timing and energization time to the electromagnetic coil,
At least one of an increase in the injection amount due to a temporary reduction in a gap between the electromagnetic coil and the armature that occurs in a predetermined period immediately after the engine is cold-started , and an increase in cylinder pressure due to the increase in the injection amount A means for correcting an increase in the cylinder pressure , based on an elapsed time after the start operation of the engine and an estimated temperature of the fuel injection valve, and a correction for reducing the amount of fuel injected from the fuel injection valve; and At least one of a pressure reduction correction of the pressure of the fuel supplied to the fuel injection valve and a delay correction of the injection timing of the fuel injected from the fuel injection valve is executed, and an elapsed time after the start operation of the engine shorter, and, as the estimated temperature is lower in the fuel injection valve, the fuel amount injected from the fuel injection valve performs a correction for a large the reduction correction amount in the predetermined period, the fuel injection valve The correction for the pressure of the fuel to be fed is that large that vacuum correction amount performed in the predetermined period, the injection timing of the fuel injected from the fuel injection valve is the correction to be large and the retard correction amount A fuel injection control device for an internal combustion engine, comprising correction means for performing a predetermined period . The fuel injection control device for an internal combustion engine according to any one of claims 1 to 4, wherein the correction means estimates the temperature of the fuel injection valve based on a coolant temperature of the engine. The fuel injection control device for an internal combustion engine according to any one of claims 1 to 4, wherein the correction means estimates the temperature of the fuel injection valve based on the temperature of air taken into the engine. The correction unit performs the correction only for a predetermined period from when the start of the engine is completed until the temperature of each part of the fuel injection valve becomes substantially uniform. Fuel injection control device for internal combustion engine. The fuel injection control device for an internal combustion engine according to any one of claims 1 to 7,
The engine is an in-cylinder injection type internal combustion engine that includes means for stocking the fuel supplied to the fuel injection valve and that directly supplies the fuel injected from the fuel injection valve into the cylinder. A fuel injection control device for an internal combustion engine. The fuel injection control device for an internal combustion engine according to claim 8, wherein the internal combustion engine is a common rail diesel engine.

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