JP6801487B2 - Fuel injection device - Google Patents

Description

The present invention relates to a fuel injection device, and more particularly to a fuel injection device for learning the fuel injection amount of an injector.

Japanese Unexamined Patent Publication No. 2014-5793 (Patent Document 1) discloses a fuel injection device for learning the fuel injection amount of an injector. This injector is mounted on a diesel engine. In this fuel injection device, the rail pressure of the common rail to which the injector is connected is variable. The learning of the fuel injection amount is periodically performed at a plurality of rail pressures (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-5793

The fuel injection amount from the injector is adjusted according to, for example, a command value received from the control device. The fuel injection amount corresponding to the command value and the actual fuel injection amount do not always match due to factors such as individual differences in the injectors and changes over time. Therefore, it is important to periodically learn the fuel injection amount of the injector and correct the command value.

In particular, the difference between the fuel injection amount corresponding to the command value and the actual fuel injection amount becomes large until the initial familiarization at the initial stage of use of the injector is completed. Therefore, it is preferable to shorten the learning cycle of the fuel injection amount until the initial familiarization of the injector is completed, thereby suppressing the deviation between the fuel injection amount corresponding to the command value and the actual fuel injection amount at an early stage.

Even when the fuel injection amount is learned at a plurality of rail pressures as in the fuel injection device disclosed in Patent Document 1, the command value is supported by shortening the learning cycle until the initial familiarization is completed. It is possible to reduce the influence of the difference between the fuel injection amount to be applied and the actual fuel injection amount. However, if the learning cycle of the fuel injection amount is maintained short even though the initial familiarization has been completed, unnecessary learning will be performed.

The present invention has been made to solve such a problem, and an object of the present invention is to prevent unnecessary learning from being performed in a fuel injection device that learns the fuel injection amount of an injector. is there.

A fuel injection device according to the present invention includes a common rail, an injector, and a control device. The rail pressure of the common rail can be changed. The injector is configured to inject fuel supplied from the common rail into the combustion chamber of the engine. The control device is configured to control the fuel injection amount of the injector by sending a command value to the injector. The control device periodically learns the fuel injection amount by calculating the difference between the fuel injection amount corresponding to the command value and the actual fuel injection amount at each of the plurality of rail pressures. Then, the control device performs a change process for lengthening the learning cycle according to the increase in the amount of heat received by the injector nozzle for each rail pressure .

When the amount of heat applied to the nozzle reaches a predetermined amount, the initial familiarization of the injector is completed. The present inventors have found that this predetermined amount differs depending on the rail pressure. In this fuel injection device, the learning cycle of the fuel injection amount is lengthened (change processing is performed) according to the increase in the amount of heat received by the nozzle of the injector for each rail pressure . Therefore, according to this fuel injection device, it is possible to suppress unnecessary learning from being performed by appropriately changing the learning cycle for each rail pressure.

In addition , in the change process , the control device has the same rail pressure when the rail pressure is the first rail pressure, when the amount of heat received is the same until the initial familiarization of the injector for each rail pressure is completed. The learning cycle is longer than that at the second rail pressure. The first rail pressure is higher than the second rail pressure.

The present inventors have found that the higher the rail pressure, the more the initial familiarization of the injector is completed when the amount of heat applied to the nozzle is small. In this fuel injection device, until the initial familiarization of the injector for each rail pressure is completed, when the amount of heat received is the same, the learning cycle is longer when the rail pressure is high than when it is low. become longer. Therefore, according to this fuel injection device, the case where the initial familiarization is approaching (the difference between the fuel injection amount corresponding to the command value and the actual fuel injection amount is small) is not approaching (command value). Since the learning cycle is longer than (the difference between the fuel injection amount corresponding to the above) and the actual fuel injection amount is large), it is possible to suppress unnecessary learning.

Preferably, in the change process at the first rail pressure , the control device makes a first after the amount of heat received at the first rail pressure reaches a predetermined first predetermined amount for the first rail pressure . The learning cycle at the rail pressure is maintained at a predetermined maximum cycle, the change process at the first rail pressure is stopped, and in the change process at the second rail pressure, the amount of heat received at the second rail pressure is the second . After reaching a predetermined second predetermined amount for the second rail pressure larger than the predetermined amount of 1, the learning cycle in the second rail pressure is maintained at the maximum cycle, and the change in the second rail pressure is performed. Stop processing .

In this fuel injection device, the learning cycle is set to the maximum cycle earlier in the case of the high rail pressure than in the case of the low rail pressure. Therefore, according to this fuel injection device, for example, every time the initial familiarization at each rail pressure is completed, the learning cycle change processing at each rail pressure can be stopped, and unnecessary learning cycle change processing can be performed. It can be suppressed.

Preferably, in the change process at the lowest rail pressure among the plurality of rail pressures to be learned , the control device reaches a predetermined predetermined amount for the rail pressure having the lowest heat amount at the lowest rail pressure. , the period of learning in lowest rail pressure is maintained at the maximum period, to stop the definitive change process to the lowest rail pressure.

In this fuel injection device, when the learning cycle is set to the maximum cycle at the lowest rail pressure, the learning cycle change process is stopped. Therefore, according to this fuel injection device, when the learning cycle at all rail pressures is set to the maximum cycle, the process of changing the learning cycle at all rail pressures is stopped, so that the learning cycle is unnecessary. It is possible to suppress the implementation of the change process.

According to the present invention, it is possible to suppress unnecessary learning in the fuel injection device that learns the fuel injection amount of the injector.

It is a schematic block diagram which shows the diesel engine. It is sectional drawing of a nozzle. It is a figure which shows the relationship between the initial familiarization period for every rail pressure, and the learning cycle for every rail pressure. It is a figure which shows the relationship between the heat quantity of a nozzle and a learning cycle at each rail pressure. It is a flowchart which shows the calculation processing procedure of the heat amount of a nozzle. It is a flowchart which shows the setting processing procedure of the learning cycle of a fuel injection amount.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals, and the description thereof will not be repeated.

[Diesel engine configuration]
FIG. 1 is a schematic configuration diagram showing a diesel engine including an embodiment of a fuel injection device according to the present invention. With reference to FIG. 1, the diesel engine 1 is a common rail type 4-cylinder in-line diesel engine, which is mounted on, for example, a vehicle.

The diesel engine (hereinafter, also simply referred to as “engine”) 1 includes an engine body 2. The engine body 2 is provided with four cylinders 3. Each cylinder 3 is provided with an injector 5 that injects fuel into the combustion chamber 4. Each injector 5 is connected to a common rail 6. The high-pressure fuel pressurized by the high-pressure pump 27 is stored in the common rail 6, and the high-pressure fuel stored in the common rail 6 is supplied to the injector 5. A nozzle 7 is provided at the tip of the injector 5.

FIG. 2 is a cross-sectional view of the nozzle 7. With reference to FIG. 2, the nozzle 7 includes a body 8 and a needle 9 movably housed in the body 8 in the axial direction. A plurality of injection holes 8a are formed at the tip of the body 8. By the action of an electromagnet (not shown) provided at the base end of the injector 5, the needle 8 moves in the axial direction of the body 9, and fuel is injected from each injection hole 8a.

With reference to FIG. 1 again, an intake passage 10 for sucking air into the combustion chamber 4 is connected to the engine body 2 via an intake manifold 11. The intake passage 10 is provided with an air cleaner 12, a compressor 14 of the turbocharger 13, an intercooler 15, and a throttle valve 16 from the upstream side to the downstream side. Further, an exhaust passage 17 for exhausting the exhaust gas after combustion is connected to the engine main body 2 via an exhaust manifold 18. The exhaust passage 17 is provided with a turbine 19 of the turbocharger 13 and a catalyst 20 with a DPF (Diesel Particulate Filter) from the upstream side to the downstream side.

Further, the engine 1 includes an EGR unit 21 that recirculates a part of the exhaust gas after combustion as exhaust gas recirculation (EGR (Exhaust Gas Recirculation)) gas into the combustion chamber 4. The EGR unit 21 is provided so as to connect the intake passage 10 and the exhaust manifold 18. The EGR unit 21 includes an EGR passage 22 for recirculating the EGR gas, an EGR valve 23 for adjusting the amount of recirculation of the EGR gas from the exhaust manifold 18 to the intake passage 10, and an EGR for cooling the EGR gas passing through the EGR passage 22. The cooler 24 includes a bypass passage 25 connected to the EGR passage 22 so as to bypass the EGR cooler 24, and a switching valve 26 for switching the flow path of the EGR gas to the EGR cooler 24 side or the bypass passage 25 side.

Further, the engine 1 includes a rotation speed sensor 28, an accelerator opening sensor 29, and an ECU (Electric Control Unit) 30. The rotation speed sensor 28 is configured to detect the rotation speed (engine rotation speed) of the engine 1. The accelerator opening sensor 29 is configured to detect the depression angle (accelerator opening) of the accelerator pedal.

The ECU 30 has a built-in CPU (Central Processing Unit) and a memory (not shown), and the engine 1 is based on the information stored in the memory and the information from each sensor (for example, the rotation speed sensor 28 and the accelerator opening sensor 29). Each device (high pressure pump 27, injector 5, throttle valve 16, EGR valve 23, switching valve 26, etc.) is controlled.

The ECU 30 can change the rail pressure of the common rail 6 by controlling the high-pressure pump 27, for example. The ECU 30 can adjust the rail pressure of the common rail 6 to any of R1 to R4 (described later), for example.

Further, the ECU 30 controls the fuel injection amount of the injector 5 by sending the command value of the fuel injection amount to the injector 5. Further, the ECU 30 learns the fuel injection amount of the injector 5. For example, the ECU 30 sends a command value for learning to the injector 5 when the engine 1 is in a no-load and fuel-cut state. The command value for learning is a command value for injecting a minute amount of fuel into the injector 5. The ECU 30 estimates the fuel injection amount actually injected from the injector 5 based on the change in the engine speed (detected by the speed sensor 28) caused by sending the command value for learning to the injector 5. The ECU 30 calculates the difference (deviation amount) between the fuel injection amount corresponding to the command value and the actual fuel injection amount. The ECU 30 learns the fuel injection amount by correcting the command value according to the calculated difference.

[Learning timing]
By operating the injector 5 in the early stage after the start of operation of the engine 1, the needle 9 and the body 8 (FIG. 2) in the nozzle 7 are rubbed together. By rubbing the needle 9 and the body 8 together, the needle 9 slides smoothly with respect to the body 8. It is also called an initial familiarization period until the needle 9 slides smoothly with respect to the body 8.

In the injector 5, the deviation between the fuel injection amount corresponding to the command value and the actual fuel injection amount becomes larger before the completion of the initial familiarization than after the completion of the initial familiarization. Therefore, before the completion of the initial familiarization of the injector 5, it is preferable to shorten the learning cycle of the fuel injection amount to suppress the deviation between the fuel injection amount corresponding to the command value and the actual fuel injection amount at an early stage.

For example, even when learning the fuel injection amount of the injector 5 at each of the plurality of rail pressures of the common rail 6, by shortening the learning cycle until the initial familiarization is completed, the fuel injection amount corresponding to the command value can be obtained. It is possible to reduce the influence of deviation from the actual fuel injection amount. However, if the learning cycle of the fuel injection amount is maintained short even though the initial familiarization has been completed, unnecessary learning will be performed.

When the amount of heat received by the nozzle 7 (FIG. 2) of the injector 5 reaches a predetermined amount, the initial familiarization of the injector 5 is completed. The present inventors have found that this predetermined amount differs depending on the rail pressure of the common rail 6. Therefore, in the engine 1 according to the present embodiment, the ECU 30 changes the learning cycle of the fuel injection amount according to the amount of heat received by the nozzle 7 of the injector 5 and the rail pressure of the common rail 6. Therefore, according to the engine 1, it is possible to suppress unnecessary learning from being performed by appropriately changing the learning cycle for each rail pressure of the common rail 6. In the engine 1 according to the present embodiment, the learning of the fuel injection amount is periodically performed at each of the plurality of rail pressures.

FIG. 3 is a diagram showing the relationship between the initial familiarization period for each rail pressure and the learning cycle for each rail pressure. With reference to FIG. 3, in the upper view, the horizontal axis represents the operating time of the engine 1 and the vertical axis represents the fuel injection amount. The learning timing when the rail pressure of the common rail 6 is R1, the learning timing when the rail pressure is R2, the learning timing when the rail pressure is R3, and the rail pressure are R4 in this order downward. The learning timing of the case is shown. In R1 to R4, the younger the number following R, the higher the pressure, which is the same in FIG.

At time t1, the initial familiarization when the rail pressure is R1 is completed. At the rail pressure R1, the learning cycle gradually becomes longer until the time t1, and after the time t1, the learning cycle becomes a predetermined cycle (a predetermined cycle). At time t2, the initial familiarization when the rail pressure is R2 is completed. At the rail pressure R2, the learning cycle gradually becomes longer until the time t2, and after the time t2, the learning cycle becomes a predetermined cycle. At time t3, the initial familiarization when the rail pressure is R3 is completed. When the rail pressure is R3, the learning cycle gradually becomes longer until the time t3, and after the time t3, the learning cycle becomes a predetermined cycle. At time t4, the initial familiarization when the rail pressure is R4 is completed. When the rail pressure is R4, the learning cycle gradually becomes longer until the time t4, and after the time t4, the learning cycle becomes a predetermined cycle.

FIG. 4 is a diagram showing the relationship between the amount of heat received by the nozzle 7 and the learning cycle at each rail pressure. With reference to FIG. 4, the horizontal axis represents the amount of heat received by the nozzle 7, and the vertical axis represents the learning cycle of the fuel injection amount of the injector 5.

When the amount of heat applied to the nozzle 7 reaches F1, the initial familiarization is completed at the rail pressure R1, and the learning cycle becomes T4 (T4> T3> T2> T1). That is, the amount of heat received F1 can be said to be the initial familiar completion threshold value at the rail pressure R1. When the amount of heat received by the nozzle 7 reaches F1, the learning cycle becomes T3 at the rail pressure R2, the learning cycle becomes T2 at the rail pressure R3, and the learning cycle becomes T1 at the rail pressure R4.

As described above, in the engine 1 according to the present embodiment, the ECU 30 injects fuel when the amount of heat received by the nozzle 7 is F1 and when the rail pressure of the common rail 6 is high pressure than when the rail pressure is low pressure. Lengthen the learning cycle of quantity. This is because the present inventors have found that the higher the rail pressure, the smaller the amount of heat applied to the nozzle 7, and the more the initial familiarization of the injector 5 is completed. Therefore, according to the engine 1, the case where the completion of the initial familiarization of the injector 5 is approaching (the difference between the fuel injection amount corresponding to the command value and the actual fuel injection amount is small) is not approaching (command). Since the learning cycle of the fuel injection amount is longer than the deviation s between the fuel injection amount corresponding to the value and the actual fuel injection amount), it is possible to suppress unnecessary learning.

Further, when the amount of heat received by the nozzle 7 reaches F2, the initial familiarization is completed at the rail pressure R2 (R1> R2), and the learning cycle becomes T4. Further, when the amount of heat received by the nozzle 7 reaches F3, the initial familiarization is completed at the rail pressure R3, and the learning cycle becomes T4. Further, when the amount of heat received by the nozzle 7 reaches F4, the initial familiarization is completed at the rail pressure R4, and the learning cycle becomes T4. That is, the heat amounts F2, F3, and F4 can be said to be the initial familiar completion thresholds at the rail pressures R2, R3, and R4, respectively.

As described above, in the engine 1 according to the present embodiment, the ECU 30 sets the learning cycle in the rail pressure R1 to T4 after the heat amount of the nozzle 7 reaches F1, and the heat amount of the nozzle 7 is F2 (F2). After reaching> F1), the learning cycle at the rail pressure R2 is set to T4. Therefore, according to the engine 1, for example, every time the initial familiarization at each rail pressure is completed, the learning cycle change processing at each rail pressure can be stopped, and the execution of unnecessary learning cycle change processing is suppressed. be able to.

[Procedure for calculating the amount of heat received by the nozzle]
FIG. 5 is a flowchart showing a procedure for calculating the amount of heat received by the nozzle 7. The process shown in this flowchart is executed at a predetermined cycle during the operation of the engine 1. That is, the calculation of the amount of heat received by the nozzle 7 is executed in a predetermined cycle (for example, on the order of milliseconds) regardless of the learning timing of the fuel injection amount.

With reference to FIG. 5, the ECU 30 calculates the heat temperature of the nozzle 7 based on the engine speed detected by the rotation speed sensor 28 and the command value of the fuel injection amount sent by the ECU 30 to the injector 5 ( Step S100). For example, the ECU 30 stores a map showing the relationship between the engine speed, the command value, and the heated temperature in the internal memory, and calculates the heated temperature of the nozzle 7 by referring to this map.

The ECU 30 calculates the amount of heat received in this cycle based on the calculated heat-heated temperature and the cycle in which this flowchart is executed (step S110). For example, the ECU 30 stores a map showing the relationship between the heat generation temperature, the cycle in which this flowchart is executed, and the heat resistance amount in the internal memory, and by referring to this map, the nozzle 7 is covered in this cycle. Calculate the amount of heat. After that, the ECU 30 updates the cumulative value of the amount of heat received by integrating the calculated amount of heat received with the cumulative value of the amount of heat received (step S120). As a result, the cumulative value of the amount of heat received by the nozzle 7 is sequentially updated. The cumulative value of the amount of heat received is stored in, for example, the internal memory of the ECU 30.

[Learning cycle setting processing procedure]
FIG. 6 is a flowchart showing a procedure for setting the learning cycle of the fuel injection amount. The processing shown in this flowchart is executed at the learning timing of the fuel injection amount, and is executed at each of the plurality of rail pressures at which the fuel injection amount learning is performed. That is, when the learning timing of the fuel injection amount arrives, the ECU 30 sequentially changes the rail pressure to execute the process shown in this flowchart at each of the plurality of rail pressures.

With reference to FIG. 6, the ECU 30 acquires the cumulative value of the amount of heat received by the nozzle 7 from the internal memory (step S200). The cumulative value of the amount of heat received by the nozzle 7 is a value that is sequentially updated through the processing of the flowchart of FIG.

The ECU 30 determines whether or not the acquired cumulative value of the amount of heat received is larger than the initial familiarization completion threshold value (step S210). For example, when the rail pressure is R1, the ECU 30 determines whether or not the cumulative value of the amount of heat received is larger than the amount of heat received F1 (FIG. 4).

When it is determined that the cumulative value of the amount of heat received is equal to or less than the initial familiar completion threshold value (NO in step S210), the ECU 30 calculates the learning cycle of the fuel injection amount based on the cumulative value of the amount of heat received and the rail pressure (NO). Step S220). For example, the ECU 30 stores a map showing the relationship between the amount of heat received by the nozzle 7, the rail pressure, and the learning cycle in the internal memory as shown in FIG. 4, and calculates the learning cycle by referring to this map. To do.

On the other hand, when it is determined that the cumulative value of the amount of heat received is larger than the initial familiarization completion threshold value (YES in step S210), the ECU 30 sets the learning cycle to a predetermined cycle (for example, the learning cycle T4 shown in FIG. 4) ( Step S230). After that, the ECU 30 stops the process of changing the learning cycle at the current rail pressure (step S240).

That is, the higher the rail pressure, the earlier the learning cycle change process is stopped. Therefore, when the learning cycle at the lowest rail pressure among the plurality of rail pressures to be learned is set to a predetermined cycle, the learning cycle The change process of is completely stopped. Therefore, according to the engine 1, it is possible to suppress the execution of unnecessary learning cycle change processing.

As described above, in the engine 1 according to the present embodiment, the ECU 30 changes the learning cycle of the fuel injection amount according to the amount of heat received by the nozzle 7 of the injector 5 and the rail pressure of the common rail 6. Therefore, according to the engine 1, it is possible to suppress unnecessary learning from being performed by appropriately changing the learning cycle for each rail pressure of the common rail 6.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims, not the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Diesel engine, 2 Engine body, 3 cylinders, 4 combustion chambers, 5 injectors, 6 common rails, 7 nozzles, 8 bodies, 9 needles, 10 intake passages, 11 intake manifolds, 12 air cleaners, 13 turbo superchargers, 14 compressors, 15 Intercooler, 16 Throttle valve, 17 Exhaust passage, 18 Exhaust manifold, 19 Turbine, 20 Catalyst, 21 EGR unit, 22 EGR passage, 23 EGR valve, 24 EGR cooler, 25 Bypass passage, 26 Switching valve, 27 High pressure pump, 28 rotation speed sensor, 29 accelerator opening sensor, 30 ECU.

Claims (3)

With a common rail that can change the rail pressure,
An injector configured to inject fuel supplied from the common rail into the combustion chamber of the engine.
A control device configured to control the fuel injection amount of the injector by sending a command value to the injector is provided.
The control device is
Learning of the fuel injection amount by calculating the difference between the fuel injection amount corresponding to the command value and the actual fuel injection amount is periodically performed at each of the plurality of rail pressures.
The have row change process to lengthen the period of the learning according to the increase of the heat amount of the nozzle of the injector rail圧毎,
In the change process, when the amount of heat received is the same until the initial familiarization of the injector for each rail pressure is completed, the rail pressure is higher when the rail pressure is the first rail pressure. Make the cycle longer than at the second rail pressure.
The fuel injection device , wherein the first rail pressure is higher than the second rail pressure . The control device is
In the change process at the first rail pressure, after the amount of heat received at the first rail pressure reaches a predetermined first predetermined amount for the first rail pressure , the first rail The cycle at the pressure is maintained at a predetermined maximum cycle, the change process at the first rail pressure is stopped, and the change process is stopped .
In the change process at the second rail pressure, the amount of heat received at the second rail pressure is larger than the first predetermined amount to a predetermined second predetermined amount for the second rail pressure. after reaching and maintaining said period in the second rail pressure to the maximum period, stopping the changing process in the second rail pressure, fuel injection device according to claim 1. The control device is
In the change process at the lowest rail pressure among the plurality of rail pressures to be learned, after the amount of heat received at the lowest rail pressure reaches a predetermined amount predetermined for the lowest rail pressure . the lowest maintaining the cycle at rail pressure to the maximum period, stopping the changing process definitive to the lowest rail pressure, the fuel injection device according to claim 2.

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