JP2003343329A - Fuel injection control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain the fuel pressure in a fuel injection valve, when fuel injection is executed at the same cycle by the fuel injection valve at least twice, from fluctuating influenced by the pressure waves caused by the former fuel injection at the latter injection time, in a fuel injection control device with a fuel accumulation chamber and the fuel injection valve connected to the pressure accumulation chamber through a pipe. <P>SOLUTION: In the interval between the former fuel injection and the latter fuel injection when injection is performed twice, when the fuel pressure in the fuel injection valve 1 is increased higher than the fuel pressure in the pressure accumulation chamber 2 influenced by the former injection, the fuel in the fuel injection valve 1 is consumed without injecting fuel. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art For example, in order to supply fuel into a high pressure cylinder such as a compression stroke, a pressure accumulating chamber common to a plurality of cylinders is provided, and fuel pressurized in the pressure accumulating chamber is injected into each cylinder. A fuel injection control device for injecting fuel by a valve is known.

In each fuel injection valve, fuel injection is started when the injection hole is opened by the valve body, and stopped when the injection hole is closed by the valve body. When fuel injection is performed in this way, the fuel pressure in the fuel injection valve decreases, and this pressure decrease is propagated to the accumulator as a negative pressure wave. The negative pressure wave propagating to the pressure accumulating chamber is reflected by the pressure accumulating chamber as an open end, and is thus propagated to the fuel injection valve as a positive pressure wave. The positive pressure wave propagated to the fuel injection valve is reflected to the fuel injection valve as a closed end, and thus propagates to the pressure accumulating chamber as a positive pressure wave. Next, the positive pressure wave propagating to the pressure accumulating chamber is reflected with the pressure accumulating chamber as an open end, and becomes a negative pressure wave and propagates to the fuel injection valve. The negative pressure wave propagated to the fuel injection valve is reflected with the fuel injection valve as the closed end, and is propagated to the accumulator as the negative pressure wave. Such propagation of the pressure wave is repeated until the pressure wave disappears due to the attenuation.

Generally, the valve opening time of each fuel injection valve is controlled according to the fuel pressure in the pressure accumulating chamber, but what actually affects the fuel injection amount is the fuel pressure in the fuel injection valve. is there. The fuel pressure in the fuel injection valve is higher than the fuel pressure in the pressure accumulation chamber when the reflected wave from the pressure accumulation chamber arrives as a positive pressure wave, and is lower than the fuel pressure in the pressure accumulation chamber when it arrives as a negative pressure wave. However, since the pressure wave disappears due to damping by the time of fuel injection in the next cycle,
At the time of fuel injection in the next cycle, the fuel pressure in the fuel injection valve hardly changes due to the arrival of the pressure wave, and almost coincides with the fuel pressure in the pressure accumulator. Thereby, when each fuel injection valve performs one fuel injection in one cycle, it does not matter in particular if the valve opening time is controlled according to the fuel pressure in the pressure accumulating chamber at the time of fuel injection. .

[0005]

[Patent Document 1] Japanese Unexamined Patent Application Publication No.
In the case where pilot fuel injection and main fuel injection are carried out in each fuel injection valve as disclosed in Japanese Patent Laid-Open No. 000-18074, or when main fuel injection and post fuel injection are carried out, etc., they are the same. In the cycle, when at least two fuel injections are performed by the same fuel injection valve, the previous fuel injection (in the relationship between the pilot fuel injection and the main fuel injection, pilot fuel injection,
The relationship between the main fuel injection and the post fuel injection is the main fuel injection. The pressure wave generated by () is a fuel injection afterward (main fuel injection in the relationship between pilot fuel injection and main fuel injection, and post fuel injection in the relationship between main fuel injection and post fuel injection). It does not disappear in a short time until, and a pressure wave may arrive at a later fuel injection time and the fuel pressure in the fuel injection valve may fluctuate significantly. In such a case, even if the valve opening time is controlled according to the fuel pressure in the pressure accumulating chamber, a desired amount of fuel cannot be injected.

Therefore, an object of the present invention is to provide a fuel injection control device having a pressure accumulating chamber and a fuel injection valve connected to the pressure accumulating chamber by a pipe, and at least twice fuel injection is performed by the same fuel injection valve in the same cycle. Is carried out,
It suppresses the fluctuation of the fuel pressure in the fuel injection valve at the time of the subsequent fuel injection due to the influence of the pressure wave due to the previous fuel injection, and controls the valve opening time at the subsequent fuel injection according to the fuel pressure in the pressure accumulating chamber. Even so, it is possible to inject a desired amount of fuel.

[0007]

A fuel injection control device for an internal combustion engine according to a first aspect of the present invention comprises a pressure accumulating chamber and a fuel injection valve connected to the pressure accumulating chamber by a pipe.
In the case where at least two fuel injections are performed by the same fuel injection valve in the same cycle, between the previous fuel injection and the subsequent fuel injection in the at least two fuel injections, When the fuel pressure in the fuel injection valve is higher than the fuel pressure in the accumulator chamber due to the influence, the fuel in the fuel injection valve is consumed without injecting the fuel.

A fuel injection control device for an internal combustion engine according to a second aspect of the present invention is the fuel injection control device for an internal combustion engine according to the first aspect, wherein the fuel injection valve opens a control valve body. And by lowering the fuel pressure in the control chamber, the injection hole valve element opens the injection hole to inject fuel, and the control valve element can be controlled freely by an electrostrictive actuator. In order to consume the fuel in the fuel injection valve, the control valve body controls the fuel pressure in the control chamber to a set opening degree so as to reduce the fuel pressure in the control chamber to such an extent that the injection hole valve body does not open the injection hole. It is characterized in that the fuel is discharged from the control chamber.

A fuel injection control device for an internal combustion engine according to a third aspect of the present invention is the fuel injection control device for an internal combustion engine according to the first aspect, wherein the fuel injection valve controls the fuel pressure in the control chamber. The injection hole valve body opens the injection hole to inject fuel by lowering the pressure, and at least two fuel outflow passages are connected to the control chamber to consume the fuel in the fuel injection valve. In order to reduce the fuel pressure in the control chamber to such an extent that the injection hole valve body does not open the injection hole, one of the two fuel outflow passages having a smaller fuel outflow rate is used to remove the fuel from the control chamber. It is characterized by being discharged.

[0010]

1 is a schematic diagram showing a fuel injection control device according to the present invention. Reference numeral 1 is a fuel injection valve arranged for each cylinder, and 2 is a pressure accumulating chamber. Each fuel injection valve 1 and the pressure accumulation chamber 2 are connected by a pipe 3. Each fuel injection valve 1 injects high-pressure fuel pressurized in a pressure accumulating chamber 2 common to each cylinder, for example, in order to directly inject fuel into a cylinder of a diesel engine or a cylinder injection type spark ignition internal combustion engine. To do. Of course, the fuel injection valve 1 can also be used to inject fuel to a port other than the cylinder, for example, an intake port.

A high pressure pump (not shown) for maintaining the desired high fuel pressure in the pressure accumulating chamber 2 is connected to the pressure accumulating chamber 2. The high-pressure pump is generally of an engine-driven type, and for example, each time two fuel injection valves complete fuel injection, the amount of fuel consumed thereby is pumped to the pressure accumulating chamber 2. A pressure sensor 4 for detecting the fuel pressure in the pressure accumulating chamber 2 is arranged in the pressure accumulating chamber 2. Reference numeral 5 is a temperature sensor for detecting the fuel temperature in the pressure accumulating chamber 2.

The fuel injection valve 1 is provided with, for example, an injection hole valve body 11 which is slidable in the axial direction, and the tip of the injection hole valve body 11 opens and closes the injection hole 12. The fuel pressure in the front end side space 13 communicating with the injection hole 12 acts on the front end side of the injection hole valve body 11, and the base end side space 1 is formed on the base end side of the injection hole valve body 11.
The fuel pressure in 4 acts. A high-pressure fuel passage 15 is formed in the fuel injection valve 1. The high-pressure fuel passage 15 communicates with the proximal space 14 via an orifice 16 and the distal space 13 via an orifice. There is no communication. The pipe 3 leading to the pressure accumulating chamber 2 described above is connected to the high pressure fuel passage 15 in the vicinity of the base end side space 14.

A valve closing spring 17 for urging the injection hole valve element 11 in the valve closing direction is arranged in the proximal space 14. A control valve body chamber 19 in which the control valve body 18 is located is provided near the proximal space 14 and the control valve body chamber 19 is provided.
Communicates with the fuel tank via the low pressure fuel passage 20. The control valve body chamber 19 and the proximal space 14 communicate with each other through a communication passage 22 having an orifice 21, and the control valve body 18 can open and close the communication passage 22 by an actuator (not shown). Controlled by.

When the communication passage 22 is closed by the control valve body 18, the high-pressure fuel supplied from the high-pressure fuel passage 15 through the orifice 16 causes the high-pressure fuel passage 15 to have the same high fuel content as the high-pressure fuel passage 15. It becomes pressure. At this time, the pressure receiving area in the valve opening direction (opposing area of the base end side space 14) and the pressure receiving area in the valve closing direction (opposing area of the tip end side space 13) are each A1 (shown by a dashed line in a perspective view). Since they are equal to each other and the fuel pressure in the tip side space 13 is the same high fuel pressure as in the high pressure fuel passage 15, the pressing force in the valve closing direction that acts on the injection hole valve body 11 by the fuel pressure in the base end side space 14. And the fuel pressure in the tip side space 13 causes the injection hole valve element 1
The pressing force in the valve opening direction acting on 1 is equal to each other and cancels each other out, and the injection hole valve body 11 is closed by the pressing force in the valve closing direction by the valve closing spring 17.

Thus, when the nozzle hole valve body 11 is closed,
At the tip end side of the seat portion of the injection hole valve body 11, the tip end side space 1
The fuel pressure of 3 does not act, and the pressure receiving area on the front end side of the injection hole valve body 11, that is, the pressure receiving area in the valve opening direction decreases from A1 to a doughnut-shaped A2 (shown by a one-dot chain line as a perspective view).
On the other hand, the pressure receiving area in the valve closing direction on the base end side of the injection hole valve body 11 is still A1, and the fuel pressure P in the front end side space 13 and the base end side space 14 is equal, but the injection hole valve body 11 Is applied with a large pressing force in the valve closing direction by (A1−A2) P = P1, and a pressing force P2 in the valve closing direction by the valve closing spring 17 is applied to ensure reliable valve closing.

When the communication passage 22 is opened by the control valve body 18, the high pressure fuel in the proximal space 14 is discharged into the orifice 2
1 flows out into the control valve body chamber 19 through the communication passage 22 and is consumed, and is returned from the control valve body chamber 19 through the low pressure fuel passage 20 to the fuel tank. Thus, the proximal space 14
The fuel pressure in the inside decreases and P ′ = (A2 · P−P2) / A
When it becomes 1, the pressing force PC (A1 · P ′ + P2) acting on the injection hole valve body 11 in the valve closing direction and the pressing force PO (A
2P) becomes equal, and the fuel pressure further decreases slightly, the pressing force in the valve opening direction exceeds the pressing force in the valve closing direction, and the injection hole valve element 11 is opened, and the injection hole valve 12 is opened. Tip side space 1
The high pressure fuel in 3 is injected.

When the injection hole valve element 11 is opened, the pressure receiving area in the valve opening direction becomes equal to the pressure receiving area in the valve closing direction, and the control valve element 18 closes the communication passage 22 so that the inside of the proximal space 14 is closed. When the fuel pressure is equal to the high fuel pressure in the front end side space 13, the injection hole valve body 11 is closed and the fuel injection is stopped. Thus, the base end side space 14 is opened and closed by the control valve body 18 to control the fuel outflow, so that the injection hole valve body 11 is opened as the fuel pressure decreases, and the fuel pressure increases. Accordingly, it functions as a control chamber that closes the nozzle hole valve element 11.

FIG. 2 is a time chart showing changes in the fuel pressure in the space 13 on the front end side of the fuel injection valve 1.
The fuel pressure P is the initial fuel pressure in the front end side space 13 before the previous fuel injection is started, and is substantially equal to the high fuel pressure in the pressure accumulating chamber 2. Injection hole valve body 1 at time t0
1 is opened to start fuel injection, and at time t1, the injection hole valve element 11 is closed to stop fuel injection. As a result, the fuel pressure in the front end side space 13 is reduced and a negative pressure wave is generated. This negative pressure wave is reflected in the pressure accumulating chamber 2 and returns to the fuel injection valve at time t2 as a positive pressure wave, and the fuel pressure in the front end side space 13 is made higher than the fuel pressure in the pressure accumulating chamber 2 until time t3.

Then, the positive pressure wave thus generated at time t3 is reflected in the pressure accumulating chamber and returns to the fuel injection valve at time t4 as a negative pressure wave, until the time t5.
The fuel pressure inside is made lower than the fuel pressure inside the pressure accumulating chamber 2. Next, the negative pressure wave generated at time t5 is reflected in the pressure accumulating chamber and returns to the fuel injection valve as a positive pressure wave at time t6, and the fuel pressure in the front end side space 13 is higher than the fuel pressure in the pressure accumulating chamber 2 until time t7. To do. Thus, immediately after fuel injection, positive pressure waves and negative pressure waves alternately arrive at the fuel injection valve until the pressure wave disappears due to attenuation, and the fuel pressure in the fuel injection valve alternates with the fuel pressure in the pressure accumulator. Raise or lower.

In general, the injection hole valve element 11 of each fuel injection valve 1
The valve opening time of is controlled according to the fuel pressure in the pressure accumulating chamber 2. However, what actually affects the fuel injection amount is the fuel pressure in the fuel injection valve, strictly speaking, in the tip side space 13. Is the fuel pressure of. As described above, the fuel pressure in the tip end side space 13 changes due to the arrival of the pressure wave. As shown by the solid line in FIG. 2, the pressure wave arriving at the front end side space 13 gradually decreases due to attenuation each time it arrives, and disappears by the time of fuel injection in the next cycle. Therefore, if only the main fuel injection is performed by each fuel injection valve 1, it is assumed that the fuel pressure in the tip end side space 13 substantially matches the fuel pressure in the pressure accumulation chamber 2 at this time. Even if the valve opening period is set based on the fuel pressure, the problem does not occur so much.

When the same fuel injection valve performs at least two fuel injections in the same cycle, as in the case of performing pilot fuel injection or post fuel injection in addition to main fuel injection, the preceding fuel injection is performed. While the pressure wave generated immediately afterward reciprocates in the pipe 3 without disappearing, the fuel injection may be performed later. If the subsequent fuel injection is to be performed when the fuel pressure in the front end side space 13 is fluctuating due to this pressure wave, the intention is to set the valve opening period based on the fuel pressure in the pressure accumulating chamber 2. It is not possible to achieve the required fuel injection amount. Further, even if the fuel pressure in the tip end side space 13 is grasped by some method, it is difficult to set the valve opening time so as to realize the intended fuel injection amount, because the fuel pressure fluctuates greatly.

The fuel injection control system according to the present embodiment suppresses the fuel pressure in the tip side space 13 from varying during the subsequent fuel injection due to the influence of the pressure wave generated by the previous fuel injection, and the fuel in the pressure accumulating chamber is suppressed. It is intended to make it possible to inject a desired amount of fuel even if the valve opening time in the subsequent fuel injection is controlled according to the pressure. Practically, the fuel pressure in the pressure accumulating chamber 2 is constantly fluctuated by the pressure wave generated by the fuel injection of each fuel injection valve 1. Therefore, the average value is adopted as the fuel pressure in the pressure accumulating chamber 2. Will be done.

In order to prevent the fuel pressure in the tip end side space 13 from fluctuating, in this embodiment, the fuel injection valve is affected by the influence of the preceding fuel injection between the preceding fuel injection and the following fuel injection. When the fuel pressure inside the fuel injection chamber becomes higher than the fuel pressure inside the accumulator, that is, when a positive pressure wave arrives at the fuel injection valve, the fuel in the fuel injection valve is consumed without injecting the fuel in the fuel injection valve. There is. That is, at this time, the control valve body 18 is opened for a short time to allow the fuel to flow out from the proximal space 14 and consume the high-pressure fuel. Control valve body 18 only for a short time
Even if the valve is opened, the fuel pressure in the proximal space 14 does not drop below P ′ = (A2 · P−P2) / A1 described above, and the injection hole valve element 11 opens and the fuel is released. Is never jetted.

If the fuel pressure in the proximal space 14 is reduced in this way, a portion of the high-pressure fuel will flow from the high-pressure fuel passage 15 into the proximal space 14 via the orifice 16, so that the fuel It is possible to reduce the fuel pressure in the injection valve 1 and suppress the incoming positive pressure wave as shown by the dotted line in FIG. If the positive pressure wave can be suppressed in this way,
After that, the pressure wave that reciprocates in the pipe 3 disappears in a short time, and does not completely disappear, and even if the pressure wave arrives at the fuel injection valve 1 at a later fuel injection point, This pressure wave can be quite small, as shown by the dotted line at. As a result, the fuel pressure in the front end side space 13 does not fluctuate greatly and becomes apart from the fuel pressure in the pressure accumulation chamber 2, and the valve opening time is controlled according to the fuel pressure in the pressure accumulation chamber 2. However, it is possible to inject a desired amount of fuel in the subsequent fuel injection.

In this embodiment, as shown in FIG. 2, when the first reflected wave from the pressure accumulating chamber 2 reaches the fuel injection valve as a positive pressure wave, the fuel is consumed in the fuel injection valve 1. There is. In order to realize such control,
It must be judged that the fuel pressure in the fuel injection valve 1 is higher than the fuel pressure in the pressure accumulating chamber 2 due to the positive pressure wave. Therefore, a pressure sensor is provided in the space 13 on the front end side of the fuel injection valve 1, in the fuel injection valve 1, or in the vicinity of the fuel injection valve 1 in the pipe 3 to detect the fuel pressure in the fuel injection valve 1. It may be estimated based on the detected pressure. When the pressure sensor is provided in the pipe 3, a strain gauge or the like that detects strain of the pipe can be used as the pressure sensor, but it is generally difficult to provide the pressure sensor in the fuel injection valve 1.

In order to judge that the fuel pressure in the fuel injection valve 1 is higher than the fuel pressure in the pressure accumulating chamber 2 without providing a pressure sensor in the fuel injection valve and its vicinity, the pressure propagates in the fuel. The pressure wave generated by the previous fuel injection is determined based on the speed at which the pressure propagates, that is, the pressure propagation speed V.
It is only necessary to estimate that the fuel has propagated to and has reached the fuel injection valve 1 again by reflection. Space 13 on the tip side of the fuel injection valve 1
The distance from the accumulator to the accumulator 2 is L1 +, as shown in FIG.
It is L2, and the time T from the end of the previous fuel injection to the arrival of the reflected negative pressure wave in the front end side space 13 of the fuel injection valve 1 is 2
It can be calculated by (L1 + L2) / V. This time T is the time from time t1 to time t2 in FIG. Thus, after a lapse of time T from the end of the previous fuel injection, the positive pressure wave reaches the fuel injection valve 1. Therefore, at this time, the fuel may be consumed in the proximal space 14 of the fuel injection valve 1. Since the pressure propagation velocity changes depending on the temperature and pressure of the fuel and the property of the fuel, it is preferable to determine the pressure propagation velocity based on these.

Further, since it is actually the base end side space 14 that consumes the positive pressure wave fuel in the fuel injection valve 1, the fuel pressure in the vicinity of the orifice 16 in the high pressure fuel passage 15 of the fuel injection valve 1 is It is preferable to open the control valve element 18 when the fuel pressure in the pressure accumulating chamber 2 is higher than the fuel pressure. This time is immediately before and immediately after the positive pressure wave arrives at the front end side space 13. Further, the positive pressure wave to be suppressed is not limited to the first reflected wave from the pressure accumulating chamber 2, and may be the reflected wave from the pressure accumulating chamber 2 after the next time as long as it is before performing the subsequent fuel injection. The control valve element 18 may be opened each time it arrives.

The actuator of the control valve body 18 is generally of an electromagnetic type, and the control valve body 18 is divided into two stages of an open position for completely opening the communication passage 22 and a closed position for completely closing the communication passage 22. It is easy to control, but the control valve body 1
It is difficult to control 8 to an arbitrary position to make the opening degree of the communication passage 22 variable. Accordingly, when an electromagnetic actuator or the like is used as the actuator of the control valve element 18, the open position for completely opening the communication passage 22 when the fuel in the fuel injection valve 1 is consumed as described above. Therefore, the fuel pressure in the proximal space 14 will drop relatively quickly.

The fuel pressure in the proximal space 14 must not drop so much that the injection hole valve body 11 is opened, and for that purpose, the control valve body 18 is opened only for a short time. I can't. Practically, the valve opening time must be made very short in consideration of the control error, and the fuel pressure in the proximal space 14 cannot be lowered to the above-mentioned pressure where fuel is not injected. Thus, although the positive pressure wave can be suppressed to some extent in the fuel injection valve 1, it cannot be suppressed or eliminated sufficiently.

FIG. 3 shows a case where the electrostrictive actuator 30 is used as the actuator of the control valve body 18, and in this case, the position of the control valve body 18 controls the voltage applied to the electrostrictive actuator. Therefore, it is possible to accurately control, that is, the opening degree of the communication passage 22 can be freely controlled. As a result, the communication passage 22 can be opened at the set opening degree without being completely opened, and the flow rate can be reduced to allow the fuel to flow out. Thus, the fuel is allowed to flow out while the fuel pressure in the fuel injection valve 1 is higher than the fuel pressure in the pressure accumulating chamber 2, and the fuel pressure in the proximal space 13 is close to the above-mentioned pressure at which the fuel is not injected. Can be lowered sufficiently. Thereby, the positive pressure wave can be sufficiently suppressed or eliminated in the fuel injection valve 1.

Here, when the fuel pressure in the front end side space 13 of the fuel injection valve 1 is higher than the fuel pressure in the pressure accumulating chamber 2, the time t2 from the time t2 until the positive pressure wave arrives and is reflected, or the time t3. It is the time between time t6 and time t7. This time is approximately equal to the fuel injection time t0 to t1 because the pressure wave arriving at the fuel injection valve is due to the previous fuel injection. Assuming that the fuel pressure in the fuel injection valve is higher than the fuel pressure in the pressure accumulating chamber during this period, the control valve body 18 may be opened over this period.

Further, as described above, since it is the base end side space 14 that consumes the positive pressure wave fuel, the fuel pressure in the tip end side space 13 is included immediately before and immediately after the fuel pressure is increased by the arrival of the positive pressure wave. Assuming that the fuel pressure in the fuel injection valve is higher than the fuel pressure in the pressure accumulator, the control valve element 18 may be opened during this period.

In FIG. 3, the control valve body 18 closes the communication passage 22 when the maximum voltage is applied to the electrostrictive actuator 30, and the control valve body 18 opens the communication passage 22 as the applied voltage decreases. Is configured. Of course, the control valve body 18 may close the communication passage 22 when no voltage is applied to the electrostrictive actuator 30, and the control valve body 18 may open the communication passage 22 as the applied voltage increases. .

FIG. 4 shows a case where an actuator that can control the position of the control valve body 18 'in three steps is used as the actuator of the control valve body 18'. In the configuration shown in FIG. 4, the control valve body chamber 19 ′ has a second communication passage 24 having a first series passage 22 ′ having a first orifice 21 ′ and a second orifice 23 ′ having a smaller diameter than the first orifice 21 ′. 'To communicate with the proximal space 14. The low-pressure fuel passage 20 ′ opens into the control valve body chamber 19 so as to face the first series passage 22 ′.

The control valve body 18 'includes a first position (solid line) for closing the low pressure fuel passage 20', a second position (closed and dashed line) for closing the first series passage 22 ', the low pressure fuel passage 20' and It is possible to control in three stages with a third position (dotted line) in which none of the first series passages 22 'is closed. By setting the control valve body 18 'to the first position, the fuel in the proximal space 14 does not flow out through the first orifice 21' and the second orifice 23 ', and the fuel in the proximal space 14 does not flow out. Becomes equal to the fuel pressure in the front end side space 13, and the injection hole valve body 11
Is closed. Further, by setting the control valve body 18 ′ to the third position, the fuel in the proximal space 14 can be stored in the first orifice 2
Control valve body chamber 1 through 1'and second orifice 23 '
Since the fuel flows through 9'to the low-pressure fuel passage 20 ', the fuel pressure in the proximal space 14 decreases and the injection hole valve element 11 is opened.

Thus, in the configuration shown in FIG. 4, unlike the configurations shown in FIGS. 1 and 3, when the injection hole valve body 11 is closed, the inside of the control valve body chamber 19 'is not at atmospheric pressure but at the base end. The pressure is the same as that of the side space 14, and thus the injection hole valve body 1
The control chamber for opening and closing 1 is the proximal space 14 including the control valve body chamber 19 '.

When the control valve body 19 'is set to the second position, the fuel in the proximal space 14 flows out to the low pressure fuel passage 20' through the control valve body chamber 19 'only via the second orifice 23'. Therefore, as compared with the case where the fuel flows out through both the first orifice 21 ′ and the second orifice 23 ′ as the third position, the decrease rate of the fuel in the proximal space 14 becomes slower. can do. As a result, the injection hole valve element 11 opens, but the valve opening speed can be reduced.

If the valve opening speed is slowed in this way, the fuel injection rate at the start of fuel injection decreases, so in the main fuel injection at the time of high load, a large amount of fuel is injected at the start of injection, and this is done all at once. It is possible to prevent a large amount of noise from being generated by the ignition and combustion.

As described above, the first and second communication passages 22 for allowing the fuel to flow out from the base end side space 14 so that the valve opening speed of the injection hole valve body 11 can be reduced as necessary. When “, 24” is provided, the control valve element 1 is used when the fuel in the fuel injection valve 1 is consumed as described above.
By causing the fuel to flow out through the second communication passage 24 ′ with 8 ′ as the second position, it is possible to reduce the flow rate and allow the fuel to flow out as in the configuration of FIG. 3. Thus, the fuel is allowed to flow out while the fuel pressure in the fuel injection valve 1 is higher than the fuel pressure in the pressure accumulating chamber 2, and the base end side space 13
It is possible to sufficiently reduce the internal fuel pressure to the vicinity of the above-mentioned pressure at which the fuel is not injected. Thereby, even with such a configuration, the positive pressure wave can be sufficiently suppressed or eliminated in the fuel injection valve 1.

In particular, when the preceding fuel injection is the pilot fuel injection and the subsequent fuel injection is the main fuel injection, a relatively large amount of pilot fuel injection can be performed in order to sufficiently reduce combustion noise. Yes, at this time, in order to prevent the fuel from adhering to the cylinder bore due to the pilot fuel injection, the pilot fuel injection is performed twice. In the two pilot fuel injections, it is possible to more reliably prevent the fuel from adhering to the cylinder bores by decreasing the first pilot fuel injection amount and increasing the second pilot fuel injection amount.

When the pilot fuel injection is performed twice as described above, the negative pressure wave generated by the first pilot fuel injection is reflected through the pressure accumulating chamber 2 and returns to the fuel injection valve as a positive pressure wave to return the fuel. When the fuel pressure in the injection valve is made higher than the fuel pressure in the pressure accumulating chamber, if the second pilot fuel injection is performed, the second pilot fuel injection amount can be increased as intended, and As a result, the positive pressure wave that arrives at the fuel injection valve can be sufficiently suppressed, and similarly to the above, during the next main fuel injection, the fluctuation of the fuel pressure in the fuel injection valve due to the pressure wave can be sufficiently suppressed. Is possible.

[0042]

As described above, according to the fuel injection control device for the internal combustion engine of the present invention, the influence of the preceding fuel injection is provided between the preceding fuel injection and the following fuel injection in at least two fuel injections. Thus, when the fuel pressure in the fuel injection valve becomes higher than the fuel pressure in the pressure accumulator, the fuel in the fuel injection valve is consumed without injecting the fuel. As a result, the positive pressure wave that has reached the fuel injection valve due to the influence of the previous fuel injection can be suppressed, and when this positive pressure wave is reflected through the pressure accumulating chamber and returns to the fuel injection valve, The fluctuation of the fuel pressure is suppressed, and the desired amount of fuel can be injected even if the valve opening time in the subsequent fuel injection is controlled according to the fuel pressure in the pressure accumulating chamber.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a fuel injection control device according to the present invention.

FIG. 2 is a time chart showing a schematic variation of fuel pressure in the space on the tip end side of the fuel injection valve.

FIG. 3 is a schematic diagram in the vicinity of a control valve body chamber in a fuel injection valve.

FIG. 4 is a schematic diagram of the vicinity of another control valve body chamber in the fuel injection valve.

[Explanation of symbols]

1 ... Fuel injection valve 2 ... Accumulation chamber 3 ... Piping 11 ... Nozzle valve body 12 ... Nozzle 13 ... Tip side space 14 ... Base end side space 15 ... High-pressure fuel passage 18, 18 '... Control valve body 19, 19 '... Control valve body chamber 20 ... Low-pressure fuel passage

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02M 47/00 F02M 47/00 P 51/06 51/06 N (72) Inventor Genichi Murakami Toyota City, Aichi Prefecture Toyota Town No. 1 F-term in Toyota Motor Corporation (Reference) 3G066 AA07 AB02 AC09 AD12 BA12 BA13 BA51 CB12 CC06T CC08T CC08U CC14 CC26 CC64T CC64U CC67 CC68U CC70 CD26 CE13 CE27 DA01 DA09 DC15 DC18 3G301 HA02 HA04 JA11 JA18 LB11 MA23 MA13 MA11 MA11 MA13 MA27 MA28 NA06 NA09 NE11 NE12 PB08A PB08Z

Claims (3)

[Claims] 1. A pressure accumulating chamber and a fuel injection valve connected to the pressure accumulating chamber by a pipe, wherein at least two fuel injections are performed by the same fuel injection valve in the same cycle, the at least two Between the first fuel injection and the second fuel injection in the two fuel injections, when the fuel pressure in the fuel injection valve is higher than the fuel pressure in the pressure accumulating chamber due to the influence of the previous fuel injection, the fuel is injected. A fuel injection control device for an internal combustion engine, wherein the fuel in the fuel injection valve is consumed without being injected. 2. The fuel injection valve is configured to open a control valve body to reduce a fuel pressure in the control chamber so that the injection hole valve body opens the injection hole to inject fuel. The control valve body can be freely controlled by an electrostrictive actuator, and in order to consume the fuel in the fuel injection valve,
The control valve body is controlled to a set opening so that the fuel pressure in the control chamber is reduced to such an extent that the injection hole valve body does not open the injection hole, so that the fuel flows out from the control chamber. The fuel injection control device for an internal combustion engine according to claim 1. 3. The fuel injection valve is for injecting fuel by opening a nozzle hole of a fuel injection valve by lowering a fuel pressure in the control chamber, and at least two fuel outflows into the control chamber. The two fuel outflow passages are connected so that the fuel pressure in the control chamber is reduced to such an extent that the injection hole valve body does not open the injection hole in order to consume the fuel in the fuel injection valve. 2. The fuel injection control device for an internal combustion engine according to claim 1, wherein the fuel having a smaller flow rate of fuel outflow is used to flow out the fuel from the control chamber.