JP2009264333A - Fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain an injection quantity of a fuel injection valve, even when the opening area of a nozzle port is changed. <P>SOLUTION: This fuel injection device 1 has the fuel injection valve 2 for forming the nozzle port 2a for injecting fuel, a common rail 5 for maintaining the fuel supplied to this fuel injection valve 2 in a high pressure state, and an ECU 8 for determining a change in the opening area of the nozzle port by controlling pressure of the fuel in the common rail 5. The ECU 8 controls the pressure of the fuel when determining reduction in the opening area of the nozzle port 2a, and maintains the injection quantity of the fuel injection valve 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel injection device for an engine.

  In a diesel engine, fuel is injected into a combustion chamber from an injection hole formed in a fuel injection valve, and combustion is realized. Deposits generated by combustion may adhere to the tip of the fuel injection valve exposed in the combustion chamber. When deposits adhere to the vicinity of the injection hole of the fuel injection valve, the opening area of the injection hole is reduced as compared with a state where no deposit is attached. That is, the cross-sectional area of the fuel flow path is reduced. For this reason, unless special measures are taken, the amount of fuel injected from the nozzle hole decreases.

  When the fuel injection control device disclosed in Patent Document 1 determines that the deposit has adhered to the vicinity of the injection hole, it extends the opening time of the injection hole and extends the fuel injection time. As a result, the amount of fuel required for combustion is supplied into the combustion chamber by increasing the injection amount.

JP-A-9-151770

  However, if the fuel injection time is extended, the afterburning period of the fuel may be extended, and the emission amount of PM (Pattern Matter) may increase.

  Therefore, an object of the present invention is to maintain the injection amount of the fuel injection valve even when the opening area of the injection hole is changed.

  The fuel injection device of the present invention that solves such a problem includes a fuel injection valve in which an injection hole into which fuel is injected is formed, a fuel accumulator that maintains fuel supplied to the fuel injection valve in a high pressure state, A first determination unit that determines that the opening area of the nozzle hole is reduced; and when the first determination unit determines that the opening area of the nozzle hole is reduced, the fuel pressure in the fuel pressure accumulating unit is And a first control means for controlling (Claim 1). With such a configuration, even if the opening area of the injection hole is reduced, the fuel injection amount can be ensured without changing the injection time. In the fuel injection device of the present invention, the fuel injection pressure into the combustion chamber is changed by changing the fuel pressure in the fuel pressure accumulating means. That is, the control means controls the fuel pressure in the fuel pressure accumulating means, and controls the fuel injection pressure into the combustion chamber.

  In particular, in such a fuel injection device, when the first determination unit determines that the opening area of the nozzle hole has been reduced, the first control unit increases the fuel pressure of the fuel pressure storage unit. It can be set as a structure (Claim 2). By adopting such a configuration, the fuel injection amount can be maintained, and a reduction in engine output can be prevented. In addition, since the fuel injection amount is maintained in this way, an increase in PM can be suppressed without extending the injection time.

  In such a fuel injection device, the fuel injection device further includes background noise acquisition means for acquiring a volume of background noise for the combustion sound of the fuel injected from the fuel injection valve, and the first determination means includes the background noise acquisition means. When it is determined that the volume of the acquired background noise exceeds a threshold value and it is determined that the opening area of the nozzle hole is reduced, the first control unit can be configured to increase the fuel pressure. (Claim 3). By setting it as such a structure, a combustion noise can be made inconspicuous by background noise. The combustion noise increases as the fuel pressure increases. However, when the background noise is large, the combustion noise that increases can be made inconspicuous. For this reason, the fuel injection device can inject a predetermined amount of fuel suitable for the driving state and obtain a desired engine output without giving a driver or other occupant discomfort due to an increase in combustion noise.

  In such a fuel injection device, the first determination means may be configured to determine a reduction in the opening area of the nozzle hole based on an injection amount deterioration learning value corresponding to a cumulative travel distance of the vehicle. (Claim 4). As the traveling distance of the vehicle increases, the amount of deposits attached to the vicinity of the nozzle hole increases, and the opening area of the nozzle hole decreases. Among them, a value obtained by integrating the travel distances operated in an operation state in which deposits are particularly likely to be generated is set as an injection amount deterioration learning value. The fuel injection device can estimate the amount of deposit near the injection hole from the injection amount deterioration learning value with respect to the cumulative travel distance, and can grasp the state in which the opening area of the injection hole is reduced. The fuel injection device can control the injection pressure on the basis of the state of the opening area of the injection hole thus grasped.

  Furthermore, the fuel injection device of the present invention includes a fuel injection valve in which an injection hole into which fuel is injected is formed, a fuel accumulating means for maintaining the fuel supplied to the fuel injection valve in a high pressure state, A second determining means for determining that the opening area has increased; and a second determining means for reducing the fuel pressure of the fuel accumulating means when the second determining means determines that the opening area of the nozzle hole has increased. And a second control means (claim 5). By setting it as such a structure, even when the opening area of a nozzle hole expands, the injection quantity suitable for the driving | running state can be maintained, without changing injection time. In particular, if the injection pressure is not changed even though the opening area of the injection hole is enlarged, the amount of fuel injected becomes excessive. For this reason, the injection quantity suitable for the driving | running state can be obtained by reducing an injection pressure.

  In the fuel injection device of the present invention, when the change in the opening area of the injection hole is determined, the fuel injection pressure from the fuel injection valve is changed, so that an injection amount suitable for the operating state is obtained, The engine output can be maintained.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing a schematic configuration of a four-cylinder diesel engine (hereinafter simply referred to as “engine”) 10 incorporating the fuel injection device 1 of the present invention. In the explanatory view of FIG. 1, a fuel injection valve 2 that injects one cylinder is shown. The fuel injection device 1 includes a fuel injection valve 2, a fuel tank 3, a fuel pump 4, and a common rail 5. The fuel injection valve 2 has a configuration in which a valve body is disposed inside a nozzle body in which an injection hole 2a for injecting fuel is formed. The valve body of the fuel injection valve 2 is pulled up by an actuator that is activated by energization. As a result, the nozzle hole 2 a formed in the fuel injection valve 2 is opened, and fuel is injected into the combustion chamber 6.

  The fuel tank 3 is a tank that stores fuel. The fuel in the fuel tank 3 is sucked into the fuel pump 4 and supplied to the common rail 5. The fuel sucked into the fuel pump 4 passes through a fuel filter 7 disposed between the fuel tank 3 and the fuel pump 4. At this time, impurities in the fuel are removed by the fuel filter 7. The common rail 5 corresponds to the fuel pressure accumulating means of the present invention. The common rail 5 maintains the fuel to be supplied to the fuel injection valve 2 in a high pressure state and supplies the high pressure fuel to the fuel injection valve 2. The common rail 5 is provided with a pressure reducing valve 5a. The pressure reducing valve 5 a allows the fuel in the common rail 5 to escape to the fuel tank 3 and depressurizes the inside of the common rail 5. The common rail 5 is provided with a rail pressure sensor 5b that detects the pressure in the common rail 5.

  The fuel injection device 1 further includes an ECU (Electronic Control Unit) 8 and a drive unit 9. The ECU 8 is electrically connected to the rail pressure sensor 5b of the common rail 5, and acquires pressure information in the common rail 5. The ECU 8 corresponds to the first control means of the present invention, and determines whether or not the pressure reducing valve 5a is to be opened based on the acquired pressure information in the common rail 5. If ECU8 judges about the state which the pressure reducing valve 5a opens and closes, the information regarding this will be transmitted to the drive unit 9. FIG. The drive unit 9 switches the open / close state of the pressure reducing valve 5a in accordance with information sent from the ECU 8. When the pressure in the common rail 5 exceeds the target rail pressure, the ECU 8 sends a signal for opening the pressure reducing valve 5a. As a result, the pressure reducing valve 5a is opened, the fuel in the common rail 5 is reduced, and the pressure in the common rail 5 is reduced. On the other hand, the ECU 8 sends a signal for closing the pressure reducing valve 5a when the pressure in the common rail 5 does not reach the target rail pressure. As a result, the pressure reducing valve 5a is closed. While the pressure reducing valve 5 a is in the closed state, fuel is supplied from the fuel pump 4 into the common rail 5. Thereby, the fuel in the common rail 5 increases, and the pressure in the common rail 5 rises. As described above, the ECU 8 controls the pressure in the common rail 5. Thereby, the injection pressure of the fuel injection valve 2 in each cylinder is controlled. Further, the ECU 8 determines the open / close state of the fuel injection valve 2 from the operating state of the engine 10, and controls the open / close state of the fuel injection valve 2 via the drive unit 9.

  FIG. 2 is an explanatory diagram showing the relationship between the injection amount of the fuel injection valve 2 and the energization time to the fuel injection valve 2. FIG. 2 shows three injection pressures of 32 MPa, 100 MPa, and 180 MPa. Such an injection pressure is determined by the pressure in the common rail 5 adjusted by the ECU 8. The energization time is related to the time during which the fuel injection valve 2 is open. That is, if the energization time is the same, the time during which the valve element is open is the same. As shown in FIG. 2, the fuel injection valve 2 increases the injection amount as the injection pressure increases if the valve opening time is the same. The values of 32 MPa, 100 MPa, and 180 MPa are examples, and the ECU 8 can control the injection pressure of the fuel injection valve 2 within the pressure range that the common rail 5 can maintain.

  Furthermore, as shown in FIG. 1, the fuel injection device 1 includes a vehicle speed sensor 11 and an NE sensor 12. The vehicle speed sensor 11 and the NE sensor 12 are electrically connected to the ECU 8, and the ECU 8 acquires information about the speed of the vehicle from the vehicle speed sensor 11 and acquires information about the rotational speed of the engine 10 from the NE sensor 12. Further, when the vehicle speed acquired from the vehicle speed sensor 11 exceeds a predetermined value, that is, when the vehicle speed is high, road noise and wind noise are large. For this reason, ECU8 judges that background noise exceeds a threshold value. Such a vehicle speed sensor 11 and the ECU 8 constitute the background noise estimating means of the present invention.

  ECU8 comprises the 1st determination means of this invention which determines that the opening area of the nozzle hole 2a changed. Hereinafter, the control process of the ECU 8 that estimates the state of the nozzle hole 2a of the fuel injection valve 2 and calculates the target injection pressure of fuel will be described. FIG. 3 is a flowchart showing an example of processing related to determination of the reduction of the nozzle hole area and calculation of the target injection pressure by the ECU 8.

  In step S1, the ECU 8 calculates an injection amount deterioration learning value (hereinafter simply referred to as “learning value”) Ta corresponding to the accumulated travel distance. The learning value Ta is a value obtained by integrating travel distances driven in an operation state in which deposits are easily generated. The operating state in which such deposits are likely to be generated is determined from the average effective pressure and the rotational speed of the engine 10, and is experimentally obtained in advance. It is presumed that as the operation is performed in such an operation state, deposits are likely to adhere to the vicinity of the nozzle hole 2a, and the opening area of the nozzle hole 2a is reduced. When the ECU 8 finishes the process of step S1, the ECU 8 proceeds to step S2.

  In step S2, the ECU 8 collates the learning value Ta calculated in step S1 with the nozzle hole area reduction determination map. FIG. 4 is an explanatory diagram showing an example of the nozzle hole area reduction determination map. The vertical axis in FIG. 4 indicates the injection amount deterioration learning value, and the horizontal axis indicates the cumulative travel distance. Further, the map has a determination value. The learning value Ta tends to increase as the cumulative travel distance increases. For this reason, as shown in FIG. 4, the injection amount deterioration learning value Ta increases corresponding to the cumulative travel distance. If the learning value Ta exceeds the determination value, it is determined that the opening area of the nozzle hole 2a is reduced in the following steps. When this determination value is a constant value, it is possible to capture a case where the learning value Ta increases rapidly in a region where the cumulative travel distance is small, that is, a case where the opening area of the injection hole is rapidly reduced. It is not possible to deal with it. For this reason, when the cumulative travel distance is small, a low value is set as the determination value. In consideration of such circumstances, the determination value is set to increase stepwise as the cumulative travel distance increases. When the ECU 8 finishes the process of step S2, the ECU 8 proceeds to step S3.

  In step S3, the ECU 8 compares the learning value Ta with the determination value A and determines whether or not the learning value Ta exceeds the determination value A. If the ECU 8 determines YES in step S3, that is, if the ECU 8 determines that the learning value Ta exceeds the determination value A, the ECU 8 proceeds to step S4 and step S5.

  In step S4, the ECU 8 determines that the opening area of the nozzle hole 2a is reduced. FIG. 5 is an explanatory diagram comparing the injection amount before the opening area of the nozzle hole 2a is reduced and the injection amount after the opening area is reduced. The vertical axis in FIG. 5 indicates the injection amount of the fuel injection valve 2, and the horizontal axis indicates the energization time to the fuel injection valve 2. Further, the solid line in FIG. 5 shows a state before the opening area of the nozzle hole 2a is reduced, and the dotted line shows a state after the opening area of the nozzle hole 2a is reduced. As shown in FIG. 5, when the opening area of the nozzle hole 2a is reduced, the injection amount during the same energization time is reduced as compared to before the opening area of the nozzle hole 2a is reduced. For example, when the energization time to the fuel injection valve 2 is t1, the injection amount in the new state is Q1, whereas the injection amount when the opening area of the injection hole 2a is reduced is Q2 (Q2 <Q To Q1).

  In step S5, the ECU 8 fixes the energization time required for opening the fuel injection valve 2 to a reference value. That is, the energization time is not extended or shortened. This reference value is a value adopted as a reference in order to inject a predetermined amount of fuel. When the ECU 8 finishes the process of step S5, the process proceeds to step S6.

  In step S6, the ECU 8 calculates a target injection pressure based on an injection pressure correction map obtained in advance from experiments or the like. FIG. 6 is an explanatory diagram showing an injection pressure correction map. The vertical axis in FIG. 6 indicates the injection pressure change amount ΔP, and the horizontal axis indicates the learning value Ta. Here, the learning value Ta acquired in step S1 is collated with the injection pressure correction map, and the injection pressure change amount ΔP is calculated. For example, if the learned value Ta calculated in step S1 is Ta1, the injection pressure change amount ΔP is calculated as ΔP1 based on the injection pressure correction map of FIG. Further, the ECU 8 adds the injection pressure change amount ΔP obtained here to the current injection pressure to calculate the target injection pressure. The ECU 8 controls the fuel pressure in the common rail 5 based on the target injection pressure calculated here, and controls the injection pressure of the fuel injection valve 2. When the ECU 8 finishes the process of step S6, the process proceeds to step S7.

  In step S7, the ECU 8 determines whether the background noise exceeds a threshold value. The ECU 8 determines that the background noise exceeds the threshold when the vehicle speed acquired from the vehicle speed sensor 11 is equal to or greater than v (km / h). When the background noise exceeds the threshold value, that is, when the vehicle speed is high, road noise and wind noise are large, so that combustion noise that increases due to an increase in the target injection pressure can be eliminated. For this reason, when the background noise exceeds the threshold value, the ECU 8 increases the target injection pressure and executes fuel injection.

Also, in the following cases, since the background noise increases, it can be determined that the background noise exceeds the threshold value.
1) When engine 10 is operated at N (rpm) or more 2) When wiper switch is ON 3) When air conditioner fan is fully open

  For example, in the case of 1), the engine noise is large without increasing the injection pressure. In the case of 2), the sound of rainfall is generated. In the case of 3), the indoor blowing sound is loud, and the combustion noise is drowned out. Furthermore, it may be determined that the background noise exceeds the threshold by combining these states, including the case based on the speed of the vehicle.

  If the ECU 8 determines YES in step S7, that is, if the ECU 8 determines that the background noise is high, the process proceeds to step S8. In step S8, the ECU 8 performs fuel injection at the set target injection pressure. The ECU 8 returns after completing the process of step S8. On the other hand, if the ECU 8 determines NO in step S7, that is, if the ECU 8 determines that the background noise is not high, the process returns to step S4.

  By the way, when the ECU 8 determines NO in step S3, that is, when it is determined that the learning value Ta is equal to or less than the determination value A, the process proceeds to step S8. In step S8, the ECU 8 performs fuel injection at the set target injection pressure. Here, the target injection pressure does not change while reaching step S8. That is, the injection is performed with the injection pressure remaining unchanged. When it is determined NO in step S3, it is not determined that the opening area of the nozzle hole 2a is reduced. In this case, an injection amount corresponding to the operating state can be obtained without changing the injection pressure.

  Next, the effect by the processing of the ECU 8 will be described. FIG. 7 is an explanatory diagram comparing the injection amount when the fuel injection pressure is in an initial state and the injection amount when the fuel injection pressure is increased when the opening area of the injection hole 2a is reduced. The vertical axis in FIG. 7 indicates the injection amount of the fuel injection valve 2, and the horizontal axis indicates the energization time for the fuel injection valve 2. In FIG. 7, the injection amount when the fuel injection pressure is in the initial state is indicated by a dotted line, and the injection amount when the fuel injection pressure is increased is indicated by a broken line. When it is determined by the ECU 8 that the area of the injection hole 2a is reduced, the relationship between the energization time of the fuel injection valve 2 and the injection amount is in the state indicated by the dotted line shown in FIG. In this state, during the energization time t1, the fuel necessary for combustion cannot be injected, and the injection amount is insufficient. In such a state, the fuel injection device 1 calculates the target injection pressure based on the injection pressure correction map and sets it as a new injection pressure P2 (P2> P1 (initial injection pressure)). The process here is step S6 of the process procedure of the ECU 8 described above. The relationship between the energization time of the fuel injection valve 2 by the injection pressure calculated here and the injection amount is as shown by the broken line shown in FIG. Thereby, in energization time t1, the injection amount before the area of the nozzle hole 2a reduces is obtained. Thereby, the fuel according to a driving | running state is injected and it can prevent the output fall of an engine.

  Next, a second embodiment of the present invention will be described. The fuel injection device of the present embodiment has the same configuration as that of the fuel injection device 1 of the first embodiment. However, the fuel injection device of the present embodiment is different from the first embodiment in the control process performed by the ECU 8. Hereinafter, a processing procedure of control of the ECU 8 in the present embodiment will be described. The ECU 8 also corresponds to the second control means of the present invention, and the ECU 8 and the NE sensor 12 correspond to the second determination means of the present invention. In addition, since the structure of the fuel-injection apparatus of a present Example is the same as Example 1, it demonstrates using the same reference number.

  The outline of the control process performed by the ECU 8 of this embodiment will be described. First, the ECU 8 estimates the actual injection amount of the fuel injection valve 2 and calculates the difference from the command injection amount. Next, the ECU 8 determines a deposit accumulation state in the nozzle hole 2a from the difference between the obtained actual injection quantity and the command injection quantity, that is, changes in the opening area of the nozzle hole 2a, and takes corresponding measures.

  First, the process of the ECU 8 that estimates the actual injection amount of the fuel injection valve and calculates the difference from the command injection amount will be described. FIG. 8 is a flowchart showing an example of a processing procedure of the ECU 8 (hereinafter referred to as “injection amount difference calculation process”) for calculating the difference between the actual fuel injection amount from the fuel injection valve 2 and the command injection amount. It is.

First, the ECU 8 performs injection for learning the injection amount of the fuel injection valve (hereinafter simply referred to as learning injection). This learning injection is a so-called very small amount of pilot injection. In step S11, the ECU 8 determines whether or not a condition for performing the learning injection is satisfied. Specifically, it is determined that the following condition is satisfied.
1) No injection when the command injection amount for the fuel injection valve 2 is zero.
2) The transmission is in a neutral state (for example, during a shift change).
3) A predetermined rail pressure is maintained.

  If the ECU 8 determines YES in step S11, that is, if it determines that the condition for implementing the learning injection is satisfied, the ECU 8 proceeds to step S12. For the transmission to be in the neutral state, for example, the shift position (shift lever operating position) is in the neutral position, or the clutch is in the OFF state, that is, the engine power is cut off from the drive wheels. (In this case, the shift position is not necessarily in the neutral position). Further, when the fuel injection device 1 is equipped with an EGR device, a diesel throttle, a variable turbo, and the like, the opening of the EGR valve, the opening of the diesel throttle, the opening of the variable turbo, etc. are used for performing the learning injection. It can also be added to the conditions.

  In step S12, the ECU 8 performs learning injection. The amount of fuel to be injected by this learning injection corresponds to the pilot injection command injection amount Qc. Next, in step S13, the ECU 8 takes in the signal from the NE sensor 12 and detects the engine speed ω. The engine speed ω is detected immediately before fuel is injected from the fuel injection valve 2 in order to detect fluctuations with high accuracy.

  Next, in step S14, the ECU 8 calculates a rotational speed fluctuation amount Δω (i) for each cylinder. For example, taking the third cylinder as an example, the difference Δω3 (i) between ω3 (i) and ω3 (i + 1) is calculated. This Δω (i) decreases monotonously when there is no injection. Let Δω (i) when monotonously decreasing during no injection be Δωp (i). On the other hand, immediately after the learning injection is performed, Δω (i) increases in each cylinder.

  Next, in step S15, the ECU 8 calculates a rotational speed increase amount δ due to learning injection for each cylinder, and calculates an average value δx. The rotational speed increase amount δ is obtained as a difference between Δωp (i) when learning injection is not performed and Δω (i) calculated in step S14. Note that Δωp (i) when learning injection is not performed decreases monotonously when there is no injection, and can be easily estimated from Δωp (i−1) before learning injection.

  Next, the ECU 8 calculates an actual injection amount Qr in step S16. The torque proportional amount Tp is calculated from the product of δx calculated in step S15 and the engine speed ω0 when the learning injection is performed. This torque proportional amount Tp is proportional to the generated torque T of the engine 10 generated by the learning injection. Further, in the engine 10, the generated torque T and the actual injection amount Qr are proportional. For this reason, the actual injection amount Qr is proportional to the calculated torque proportional amount Tp. Therefore, the actual injection amount Qr can be estimated by the following formula (1) based on the product of the torque proportional amount Tp and the proportional constant k calculated in advance.

      Qr = k · δx · ω0 (∵Tp = δx · ω0) (1)

  Thus, the actual injection amount Qr is estimated by the processing of the ECU 8. The ECU 8 proceeds to step S17 after step S16. In step S17, the ECU 8 calculates a difference ΔQ between the actual injection amount Qr of the learning injection in step S12 and the command injection amount Qc. Here, as shown by the following equation (2), the difference ΔQ is obtained by subtracting the command injection amount Qc from the actual injection amount Qr. That is, the difference ΔQ may be a negative value.

                  ΔQ = Qr−Qc (2)

  The ECU 8 returns after completing the process of step S17. By the way, when the ECU 8 determines NO in step S11, that is, when it determines that the learning execution condition is not satisfied, it returns.

  In this way, the ECU 8 calculates the difference ΔQ between the actual injection amount Qr and the command injection amount Qc. Next, the control process of the ECU 8 for estimating the state of the injection hole 2a of the fuel injection valve 2 and calculating the target injection pressure based on the difference ΔQ calculated in this way will be described. FIG. 9 is a flowchart illustrating an example of processing for calculating the target injection pressure by the ECU 8.

  In step S21, the ECU 8 executes an injection amount difference calculation process. This process is the process shown in the flowchart of FIG. By this process, a difference ΔQ between the actual injection amount Qr and the command injection amount Qc in the fuel injection valve 2 is calculated.

  In step S22, the ECU 8 compares the difference ΔQ with the determination value B, and determines whether or not the difference ΔQ is equal to or less than the determination value B. Here, the determination value B is an allowable threshold for the decreasing injection amount and is a preset value. Here, the determination value B is a negative value. If the ECU 8 determines YES in step S22, that is, if it is determined that the difference ΔQ is equal to or less than the determination value B, the ECU 8 proceeds to step S23 and step S24.

  The ECU 8 determines in step S23 that the opening area of the nozzle hole 2a is reduced. In step S24, the ECU 8 fixes the energization time required for opening the fuel injection valve 2 to a reference value. Steps S23 and S24 correspond to steps S4 and S5 in the control process of the ECU 8 in the first embodiment. Here, detailed description thereof is omitted. When the ECU 8 finishes the processes of step 23 and step S24, it proceeds to step S25.

  In step S25, the ECU 8 calculates a target injection pressure based on an injection pressure correction map obtained in advance from experiments or the like. FIG. 10 is an explanatory view showing an injection pressure correction map. FIG. 10 shows the injection pressure change amount ΔP on the vertical axis and the difference ΔQ on the horizontal axis. Here, the difference ΔQ acquired in step S21 is collated with the injection pressure correction map to calculate the injection pressure change amount ΔP. Further, the ECU 8 adds the injection pressure change amount ΔP obtained here to the current injection pressure to calculate the target injection pressure. For example, if the difference ΔQ calculated in step S21 is ΔQb, the injection pressure change amount ΔP is calculated as ΔPb based on the injection pressure correction map of FIG. When the ECU 8 finishes the process of step S25, the process proceeds to step S26.

  In step S26, the ECU 8 determines whether the background noise exceeds a threshold value. This process corresponds to step S7 in the control process of the ECU 8 in the first embodiment. Since the processing content here is also the same, the detailed description is abbreviate | omitted. If the ECU 8 determines YES in step S26, that is, if the ECU 8 determines that the background noise is high, the process proceeds to step S27. In step S27, the ECU 8 performs fuel injection at the set target injection pressure. The ECU 8 returns after completing the process of step S27. On the other hand, if the ECU 8 determines NO in step S26, that is, if the ECU 8 determines that the background noise is not high, the process returns to step S23.

  By the way, when the ECU 8 determines NO in step S22, that is, when it is determined that the difference ΔQ is larger than the determination value B, the process proceeds to step S28. In step S28, the ECU 8 compares the difference ΔQ with the determination value C, and determines whether or not the difference ΔQ is equal to or greater than the determination value C. Here, the determination value C is a threshold value that is set in advance and is a threshold at which combustion is normally performed even when the actual injection amount Qr exceeds the command injection amount Qc. If the ECU 8 determines YES in step S28, that is, if the ECU 8 determines that the difference ΔQ is greater than or equal to the determination value C, the ECU 8 proceeds to step S29.

  In step S29, the ECU 8 determines that the opening area of the nozzle hole 2a is enlarged. Deposits that have adhered to the vicinity of the nozzle hole 2a may be peeled off for some reason. When the deposit is peeled off, the opening area of the nozzle hole 2a is enlarged. If it is determined that the difference ΔQ is greater than or equal to the determination value C, it is determined that the opening area of the nozzle hole 2a has increased.

  Next, in step S30, the ECU 8 fixes the energization time required for opening the fuel injection valve 2 to an initial value. That is, the energization time is not extended or shortened. When the ECU 8 finishes the process of step S30, the process proceeds to step S31.

  In step S31, the ECU 8 calculates a target injection pressure based on the injection pressure correction map of FIG. Here, the difference ΔQ acquired in step S21 is collated with the injection pressure correction map to calculate the injection pressure change amount ΔP. Further, the ECU 8 adds the injection pressure change amount ΔP obtained here to the current injection pressure to calculate the target injection pressure. If the opening area of the injection hole 2a is expanded in the state where the target injection pressure is increased in step S25, if the fuel is continuously injected at the increased target injection pressure, the supply of fuel becomes excessive. In step S31, a measure is taken to restore the fuel injection pressure. When the ECU 8 finishes the process of step S31, it proceeds to step S27, injects fuel, and returns.

  By the way, when the ECU 8 determines NO in step S28, that is, when it is determined that the difference ΔQ is larger than the determination value C, the ECU 8 proceeds to step S27 to inject fuel and return. If NO is determined in step S28, the injection hole 2a of the fuel injection valve 2 is injected so as to have an appropriate injection amount with respect to the injection hole area, so that the state is maintained as it is.

  In the present embodiment, in addition to the effects of the fuel injection device 1 of the first embodiment, when the opening area of the injection hole 2a is expanded, the fuel injection pressure is decreased to inject fuel suitable for the operating state. it can. Thereby, excessive fuel injection can be suppressed.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited thereto. Various modifications of these embodiments are within the scope of the present invention. It is apparent from the above description that various other embodiments are possible within the scope.

It is explanatory drawing which showed schematic structure of the diesel engine incorporating the fuel-injection apparatus of this invention. It is explanatory drawing which showed the relationship between the injection quantity of a fuel injection valve, and the energization time to a fuel injection valve. It is the flowchart which showed an example of the process regarding determination of reduction of the nozzle hole area and calculation of target injection pressure which ECU performs. It is explanatory drawing which showed an example of the nozzle hole area reduction determination map. It is explanatory drawing which compared the injection quantity before the opening area of a nozzle hole reduces, and the injection quantity after the opening area of a nozzle hole reduced. It is explanatory drawing which showed the injection pressure correction map of Example 1. FIG. When the opening area of the injection hole is reduced, it is an explanatory diagram comparing the injection amount when the fuel injection pressure is in an initial state and the injection amount when the fuel injection pressure is increased. It is the flowchart which showed an example of the process of ECU which calculates the difference of the actual injection quantity of fuel from a fuel injection valve, and instruction | command injection quantity. It is the flowchart which showed an example of the process which calculates target injection pressure by ECU. It is explanatory drawing which showed the injection pressure correction map of Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection apparatus 2 Fuel injection valve 2a Injection hole 5 Common rail 8 ECU
9 Drive unit 10 Engine 11 Vehicle speed sensor 12 NE sensor

Claims (5)

A fuel injection valve in which an injection hole into which fuel is injected is formed;
Fuel accumulating means for maintaining the fuel supplied to the fuel injection valve in a high pressure state;
First determination means for determining that the opening area of the nozzle hole is reduced;
When the first determination means determines that the opening area of the nozzle hole is reduced, the first control means for controlling the fuel pressure in the fuel pressure storage means;
A fuel injection device comprising: The fuel injection device according to claim 1, wherein
The fuel injection apparatus according to claim 1, wherein when the first determination means determines that the opening area of the nozzle hole is reduced, the first control means increases the fuel pressure of the fuel accumulating means. The fuel injection device according to claim 1, wherein
A background noise acquisition means for acquiring a volume of background noise about the combustion sound of the fuel injected from the fuel injection valve;
When the first determination unit determines that the volume of the background noise acquired by the background noise acquisition unit exceeds a threshold and determines that the opening area of the nozzle hole is reduced, the first control is performed. The fuel injection device characterized in that the means increases the pressure of the fuel. The fuel injection device according to claim 1, wherein
The fuel injection device according to claim 1, wherein the first determination unit determines reduction of the opening area of the injection hole based on an injection amount deterioration learning value corresponding to a cumulative travel distance of the vehicle. A fuel injection valve in which an injection hole into which fuel is injected is formed;
Fuel accumulating means for maintaining the fuel supplied to the fuel injection valve in a high pressure state;
Second determination means for determining that the opening area of the nozzle hole has increased,
A second control means for lowering the fuel pressure of the fuel accumulating means when the second determining means determines that the opening area of the nozzle hole has expanded;
A fuel injection device comprising:

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