JP2011112037A - Fuel injection device of diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance further NOx reduction and fuel consumption rate improvement through the application of operation of injection rate control with a shelf in an operation range suitable for the injection rate control with a shelf, and improve reliability of the fuel injection rate control with a shelf by executing avoidance control through the detection of abnormalities when a cylinder not surely performing the fuel injection rate control with a shelf exists. <P>SOLUTION: A fuel injection device 2 which contains a fuel injection valve 4 for injecting fuel and a first and second solenoid valves 18, 20 in a first and second return pipes 14, 16 for returning fuel to a fuel tank 8, is equipped with a control device 38 for executing fuel injection with a shelf forming a shelf part for stagnating injection pressure for a given period with respect to fuel injection pressure injected from a fuel injection valve 4 by closing the second solenoid valve 20 and then the first solenoid valve 18 after certain timing, and switches between injection with a shelf and normal injection based on an engine rotation speed and engine load. When abnormalities are detected in an area of injection with a shelf, the operating condition is switched to the normal injection. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuel injection device that injects fuel into a combustion chamber from a fuel injection valve such as a direct injection diesel engine.

The combustion of a diesel engine is greatly influenced by the state of fuel injection into the combustion chamber, particularly the fuel injection rate. Fuel injection rate control is performed to make the exhaust gas clean and highly efficient. For example, with an electronically controlled unit pump injection device, as shown in FIG. 9, with a shelf that forms a shelf where the injection pressure stagnates for a certain period in the process of increasing the injection pressure with respect to a change in crank angle (elapsed time) Injection rate control is performed.
By performing this shelf-attached injection, in the initial stage of injection, the fuel supply amount is suppressed to suppress combustion and NOx generation is prevented, and in the late stage of injection, the fuel injection rate is increased to increase the efficiency of combustion. Both NOx reduction and fuel efficiency improvement can be achieved.

On the other hand, Japanese Patent No. 3716211 by the present applicant has been proposed as Patent Document 1 that discloses a technique related to the shelf-mounted injection. An outline of the fuel injection device disclosed in Patent Document 1 will be described with reference to FIG.
The fuel injection device 01 for injecting fuel includes a fuel injection valve 03, an injection pipe 05 for guiding the fuel to the fuel injection valve 03, and a fuel delivery means (fuel) for delivering fuel from the fuel tank 07 to the injection pipe 05 through a delivery pipe 09. Pump) 011, first return pipe 013 and second return pipe 015 for returning fuel from the injection pipe 05 to the fuel tank 07, first electromagnetic valve 017 for intermittently opening (closing) the first return pipe 013, and second return A second electromagnetic valve 019 that intermittently opens (closes) the pipe 015, a plunger 023 of a fuel injection pump 021 that pumps fuel sent from the fuel delivery means 011 to the fuel injection valve 03, and a cam 025 that drives the plunger 023 It has.
The first return pipe 013 is provided with a throttle 027 and a check valve 029. Similarly, the second return pipe 015 is provided with a throttle 031 and a check valve 033. Further, the delivery pipe 09 is provided with a relief valve 035 and a check valve 037.
The first electromagnetic valve 017 and the second electromagnetic valve 019 have different fuel flow rates at the time of opening due to the operation of the throttles 027 and 031. The fuel flow rate when the first electromagnetic valve 017 is opened is different from that of the second electromagnetic valve 019. It is set to be smaller than the fuel flow rate at the time of opening, and the operation of the first electromagnetic valve 017 and the second electromagnetic valve 019 is controlled by the control device 039.

An operation procedure of the fuel injection device 01 configured as described above will be described.
First, the first and second electromagnetic valves 017 and 019 are opened, and the plunger 023 is raised. The first electromagnetic valve 017 closes at the time when fuel injection is desired to start (T1, see FIG. 9). Thus, the fuel injection rate becomes the first stage injection rate shown from T1 to T2 in FIG. That is, when the first electromagnetic valve 017 is closed, only the second return pipe 015 returns the fuel from the injection pipe 05 to the fuel tank 07, the fuel pressure in the injection pipe 05 rises, and the fuel injection valve Injection is started when the valve opening pressure of 03 needle valve is exceeded.

Subsequently, after an arbitrary time has elapsed (T2), the first electromagnetic valve 017 is opened and at the same time the second electromagnetic valve 019 is closed. Since the fuel flow rate when the first solenoid valve 017 is opened is smaller than the fuel flow rate when the second solenoid valve 019 is opened, the fuel injection rate is shown by T2 to T3 in FIG. 9 by opening the first solenoid valve 017. This is the second stage injection rate.
Furthermore, the first electromagnetic valve 017 is also closed after an arbitrary time has elapsed (T3). As a result, the fuel injection rate becomes the third stage injection rate shown from T3 to T4.
Furthermore, the fuel injection is completed by opening the first electromagnetic valve 017 and the second electromagnetic valve 019 again at an arbitrary time (T4). And the characteristic of the injection rate with a shelf which controlled the fuel injection rate in three steps as shown in FIG. 9 can be acquired.

Japanese Patent No. 3716211

  However, Patent Document 1 discloses a system for controlling the injection rate with shelves by shifting the rising timing of the drive current with respect to the two solenoid valves as described above and opening and closing the solenoid valves with a phase difference. Is applied to improve the NOx reduction and fuel efficiency by applying the injection rate control operation with shelves in the region where the injection rate control with shelves is effective in relation to the engine operation region. In the driving range, the fuel injection rate control is emphasized without carrying out the injection rate control with shelves, and the injection rate control emphasizing the reduction of PM (particulate matter) emission is performed according to the driving region. It is not disclosed until the application of the injection rate control is switched.

Patent Document 1 does not disclose any avoidance control when the injection rate control with shelves is not reliably performed.
In order to reliably perform the injection rate control with a shelf, as shown in FIG. 3, it is necessary to ensure a sufficient shelf pressure so that the shelf pressure P is equal to or higher than the nozzle opening pressure for pushing up the needle valve of the injection nozzle. However, due to the influence of variations in the nozzle valve opening pressure of the injection nozzle and the change in the temperature of the fuel, the shelf pressure does not reliably exceed the nozzle opening pressure and the injection nozzle does not open at the specified timing. There is a problem that jets with shelves are not made.

In particular, in multiple cylinders, fuel temperature changes are likely to occur between cylinders depending on the piping position of the injection pipe, making it impossible to reliably realize shelf injection rate control in the required operating range for all cylinders, and robustness of injection rate control. There is a tendency to cause a problem that (system stability against disturbance) cannot be secured.
If this shelf-injection rate control is not performed reliably, the injection timing is substantially delayed, and adverse effects such as deterioration of the fuel consumption rate, unstable engine operation due to exhaust temperature rise and misfire, and discharge of unburned fuel, etc.

  Therefore, when there is a cylinder that cannot realize the injection rate control with a shelf, it is necessary to detect the abnormality of the cylinder immediately and take a countermeasure such as returning to the normal control without the shelf to protect the engine. .

  Therefore, in view of the problems of the related art, the present invention further improves NOx reduction and fuel efficiency improvement by applying the operation of the injection rate control with shelves in the operation region suitable for the injection rate control with shelves, It is an object of the present invention to improve the reliability of shelf-equipped injection rate control by detecting an anomaly when there is a cylinder for which the injection rate control with shelf is not reliably performed and performing avoidance control.

  In order to solve the above-described problems, the present invention provides a fuel injection valve that injects fuel, an injection pipe that guides the fuel to the fuel injection valve, and a fuel delivery means that delivers fuel from a fuel tank to the injection pipe. , First and second return pipes for returning fuel from the injection pipe to the fuel tank, a first valve mechanism for interrupting the first return pipe, and a second valve mechanism for interrupting the second return pipe. In the fuel injection device, the fuel flow rate when the first valve mechanism is opened is set to be smaller than the fuel flow rate when the second valve mechanism is opened, and when the fuel is supplied to the fuel injection valve, the second valve mechanism Fuel injection that performs shelf-attached injection in which the first valve mechanism is closed after a certain timing and a shelf portion is formed in which the fuel injection pressure injected from the fuel injection valve stagnate for a certain period of time. The fuel injection rate control Stage, characterized in that it has a switching control means for switching between normal injection simultaneously close the said shelf with injection first and second valve mechanism based on engine speed and engine load.

  According to this invention, since the injection with the shelf and the normal injection are switched and operated based on the engine speed and the engine load, the NOx reduction effect is achieved by the injection with the shelf in the region where the injection rate control with the shelf is effective depending on the operation region. And improving fuel efficiency by improving combustion efficiency, and performing normal injection without shelves in an area where the injection rate control with shelves is not appropriate makes it possible to reduce NOx and improve fuel efficiency in the entire operating range. Both can be further improved.

In the present invention, it is preferable that the switching control means switches so that the shelf-attached injection is performed in a load region in which the engine speed and the load are medium.
That is, in a high rotation and high load range, the fuel injection rate is more important than the exhaust gas purification function by the shelf-equipped injection, so the shelf-equipped injection is not suitable. In the middle rotation / middle load range, NOx is actively reduced and the exhaust gas purifying function is exhibited, which is suitable for shelf-equipped injection. In the low rotation and low load range, the injection pressure is low and the injection pressure is further reduced by the shelf injection, so there is a concern about the increase in PM (particulate matter) discharge. Not suitable.
That is, it is suitable for shelf injection because the NO reduction effect is large at medium rotation and medium load, but is not suitable for shelf injection because high fuel efficiency is important at high rotation and high load and PM reduction is important at low rotation and low load.
In this way, in the entire driving range, it is possible to switch between the shelf-equipped injection and the normal injection so as to achieve overall improvement in fuel efficiency, reduction in PM emissions, and NOx reduction.

  In the present invention, it is preferable that the fuel injection rate control means includes an injection abnormality determination unit with shelves that determines that there is a cylinder in which the shelf injection is not performed during the operation of the shelf injection. When the determination unit determines that the shelf-attached injection is not performed, the normal injection may be returned.

  By configuring in this way, when the injection with the shelf is not accurately performed at the time of the injection with the shelf, the fuel injection timing is substantially delayed, which is caused by the deterioration of the fuel consumption rate, the exhaust temperature rise or the misfire. When it is detected that fuel injection with shelves is not being performed, the adverse effects such as unstable engine operation and unburned fuel discharge can be avoided by returning to normal injection. Reliability of injection rate control with shelves can be improved.

  Further, the shelf-equipped injection abnormality determining means determines the abnormality of the shelf-equipped injection based on an increase amount or an increase rate with respect to the closing period of the second valve mechanism at the time of engine shipment based on the closing period of the second valve mechanism. Good.

  The closing period of the second valve mechanism corresponds to the energization time of the solenoid valve shown in FIGS. 3 and 7 and corresponds to the amount of fuel injected from the fuel injection valve. In a cylinder in which supplementary injection is normally executed, the injection amount is increased and the exhaust temperature is increased in order to ensure a constant output by using the output decrease in the abnormal cylinder as an engine. For this reason, it is possible to determine whether or not shelf-equipped injection is normally executed in all the cylinders by detecting an increase in the exhaust gas temperature and an increase in the fuel injection amount in the other cylinders. Therefore, with reference to the closing period of the second valve mechanism at the time of engine shipment, it can be determined whether or not there is a cylinder in which an abnormality in shelf injection has occurred, based on the amount of increase or the rate of increase.

  Further, the shelf-equipped injection abnormality determining means may determine abnormality of the shelf-equipped injection based on a variation in the exhaust temperature between the cylinders or an increase amount or a rate of increase with respect to the exhaust temperature at the time of engine shipment.

As described above, when there is a cylinder with an abnormal shelf injection, in the cylinder in which the shelf injection is normally executed, the injection amount is increased in order to compensate for a decrease in the output in the abnormal cylinder and ensure a constant output as an engine. As a result, the exhaust temperature rises. For this reason, when the exhaust temperature rise in other cylinders is detected and the absolute value of the exhaust temperature rises or the rate of increase with respect to the exhaust temperature at the time of shipment is normal for all cylinders It can be determined whether or not it is executed.
Furthermore, if there are cylinders that are not properly performing shelf-equipped injection, the exhaust temperature between the cylinders will vary, so the exhaust temperature of each cylinder is detected and an abnormality in shelf-based injection occurs based on the amount of variation. It can be determined whether or not a cylinder exists.

According to the present invention, since the shelf-mounted injection and the normal injection are switched and operated based on the engine speed and the engine load, the NOx reduction effect is achieved by the shelf-mounted injection in the region where the injection rate control with the shelf is effective depending on the operation region. And improving fuel efficiency by improving combustion efficiency, and performing normal injection without shelves in an area where the injection rate control with shelves is not appropriate makes it possible to reduce NOx and improve fuel efficiency in the entire operating range. And the PM reduction effect can be improved.
Furthermore, the reliability of the injection rate control with a shelf can be improved by detecting the abnormality when there is a cylinder for which the injection rate control with the shelf is not reliably performed and performing avoidance control.

1 is an overall configuration diagram showing an embodiment of the present invention. It is a block diagram of the configuration of the fuel injection rate control means. It is a time chart which shows the opening / closing operation | movement of the solenoid valve of injection with a shelf. It is explanatory drawing which shows the injection pressure characteristic of normal injection. It is explanatory drawing of an electricity supply timing map. It is explanatory drawing of the electricity supply timing map at the time of abnormality. It is explanatory drawing of the operation signal pattern to a solenoid valve. It is explanatory drawing of a prior art. It is explanatory drawing of a prior art.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention to that unless otherwise specified.

With reference to FIG. 1, the whole block diagram of the fuel-injection apparatus concerning this invention is demonstrated.
The fuel injection device 2 for injecting fuel includes a fuel injection valve 4, an injection pipe 6 that guides the fuel to the fuel injection valve 4, and a fuel pump that sends fuel from the fuel tank 8 to the injection pipe 6 through a delivery pipe 10 (fuel delivery). Means) 12, a first return pipe 14 and a second return pipe 16 for returning fuel from the injection pipe 6 to the fuel tank 8, and a first electromagnetic valve (first valve mechanism) for intermittently opening and closing the first return pipe 14 (first valve mechanism). 18, a second solenoid valve (second valve mechanism) 20 that intermittently opens (closes) the second return pipe 16, and a plunger of a fuel injection pump 22 that pumps fuel sent from the fuel pump 12 to the fuel injection valve 4. 24 and a cam 26 for driving the plunger 24.

The first return pipe 14 is provided with a throttle 28 and a check valve 30, and the second return pipe 16 is provided with only a check valve 32. Further, the delivery pipe 10 is provided with a relief valve 34 and a check valve 36.
The first solenoid valve 18 and the second solenoid valve 20 are composed of solenoid valves having the same flow characteristics, and the fuel flow rate in the solenoid valve itself when the first solenoid valve 18 and the second solenoid valve 20 are opened is the same. When the first electromagnetic valve 18 is opened, the throttle 28 is set so that the fuel flow rate flowing through the first return pipe 14 is smaller than the fuel flow rate flowing through the second return pipe 16 when the second electromagnetic valve 20 is opened. Has been.

  Further, an opening / closing signal is output from the control device (fuel injection rate control means) 38 to the first electromagnetic valve 18 and the second electromagnetic valve 20 to control the operation. The control device 38 mainly includes an energization timing switching means (switching control means) 40, a shelf-attached injection abnormality determination means 42, and an abnormality energization timing setting means 44.

  Before describing the operation of the fuel injection device 2 configured as described above with reference to the block diagram of FIG. 2, the shelf-mounted injection by the shelf-mounted injection control means 50 and the normal injection generated by the normal injection control means 52 are described. explain.

  In the shelf-equipped injection control means 50, as shown in FIG. 3, first, the plunger 24 ascends with the first and second electromagnetic valves 18, 20 open. The second solenoid valve 20 is closed at a time (crank angle) θ1 when it is desired to start fuel injection. As a result, the injection pressure becomes the first stage injection pressure indicated by θ1 to θ2, as shown in FIG. That is, when the second solenoid valve 20 is closed, only the first return pipe 14 returns the fuel from the injection pipe 6 to the fuel tank 8, and the fuel pressure in the injection pipe 6 rises gradually, and the fuel The injection is started when the valve opening pressure of the needle valve of the injection valve 4 is exceeded. However, since a part of the fuel is returned to the fuel tank 8 by the throttle 28 of the first return pipe 14, the pressure in the injection pipe 6 stagnates at a constant pressure to form a shelf A.

Subsequently, the first electromagnetic valve 18 is closed at an arbitrary time θ2 delayed by a predetermined timing from θ1 in the state in which the shelf A is formed. As a result, the first return pipe 14 and the second return pipe 16 are closed, and suddenly rise from the shelf A to become the second stage injection pressure.
Furthermore, the fuel injection is completed by opening the first electromagnetic valve 18 and the second electromagnetic valve 20 again at an arbitrary time θ3. And the characteristic of the two-step fuel injection rate which has the shelf A as shown in FIG. 3 can be obtained.
In the drive currents of the first solenoid valve 18 and the second solenoid valve 20, a indicates a rising transient current, b indicates a starting current, c indicates a holding current, and d indicates a falling transient current.

  Further, in the normal injection control means 52, as shown in FIG. 4, the first electromagnetic valve 18 and the second electromagnetic valve 20 are simultaneously closed with the relationship between θ1 and θ2 delayed by the predetermined timing at the same time. By doing so, one mountain-shaped injection rate characteristic that does not form the shelf A of FIG. 3 is generated.

  Next, the operation of the control device 38 will be described along the flow of the configuration block diagram of FIG. First, in the energization timing switching means 40, based on the input signals of the engine speed Ne and the engine load Le, it is determined whether the operation state is suitable for the shelf-equipped injection, and the shelf-equipped injection and the normal injection are switched. At the time of this switching, the energization timing is switched based on the energization timing map 54 as shown in FIG.

  The energization timing map 54 takes the engine speed Ne and the engine load Le on the vertical axis and the horizontal axis, and divides the entire range of use of the engine speed into, for example, an operating region of 10 divisions. For example, the operation area is divided into 10 divisions, and θ1 that is the closing timing of the second electromagnetic valve 20 and θ2 that is the closing timing of the first electromagnetic valve 18 are set at the intersections, respectively.

In the shaded area of FIG. 5 where the engine speed Ne and the engine load Le are medium-medium-load, θ1 and θ2 are set as separate timings, and are θ2 having a predetermined timing delay from θ1. Therefore, when the engine speed and the load are within the shaded area, the shelf-equipped injection control means 50 executes the shelf-equipped injection according to the energization timing of θ1 and θ2.
In the low rotation low load region or the high rotation high load region outside the shaded region of the energization timing map 54, one energization timing of θ1 = θ2 is set, and the first injection valve 52 is controlled by the normal injection control means 52. The second solenoid valve 20 is simultaneously controlled at the set timing to perform normal injection.
In the example of the energization timing map 54 shown in FIG. 5, θ1 and θ2 are shown as examples set at pre-top dead center (BTDC) angles.
Thus, by using the energization timing map 54, switching between the shelf-equipped injection and the normal injection can be easily performed based on the engine speed Ne and the load Le.

  Next, when the shelf-equipped injection control means 50 is executing the shelf-equipped injection, the shelf-equipped injection abnormality determining means 42 determines whether or not the shelf-equipped injection is reliably performed in each cylinder. The shelf-attached injection abnormality determining means 42 is supplied with signals of exhaust gas temperature for each cylinder and energization time for each cylinder. This energization time indicates the T time in FIG. 7 and indicates a period in which energization starts at the timing of θ1 in the second electromagnetic valve 20 and is fully closed.

  Based on the exhaust gas temperature for each cylinder and the energization time signal for each cylinder, in any one of the energization period increase determination unit 58, the exhaust temperature rise determination unit 60, or the exhaust temperature cylinder variation determination unit 62, Or the result of a some determination part is integrated and it is determined whether the injection with a shelf is performed normally.

  If there is a cylinder with an abnormal shelf-mounted injection, in the cylinder in which the shelf-mounted injection is normally executed, the injection amount is increased to compensate for a decrease in the output of the abnormal cylinder and ensure a constant output as an engine, and the exhaust temperature Rises. For this reason, it is possible to determine whether or not shelf-equipped injection is normally executed in all the cylinders by detecting an increase in the exhaust gas temperature and an increase in the fuel injection amount in the other cylinders.

Accordingly, the energization period increase determination unit 58 includes the reference energization calculated based on the fuel injection amount serving as a reference when the shelf-equipped injection is normally executed in all the cylinders when the engine speed Ne is the load Le. When the time t ₀ , that is, the reference energization time t ₀ at the time of shipment is set, and the increase rate of the energization time t in any cylinder reaches a certain ratio or more with respect to the reference energization time t ₀ . It is determined that an abnormal cylinder exists.
Alternatively, it is possible to determine that an abnormal cylinder exists when the absolute value of the energization time t in any of the cylinders exceeds the allowable value.

Like the conduction period increased determination unit 58 also in the exhaust temperature rise judgment unit 60, the reference exhaust temperature Tex 0 of the exhaust temperature in normal use _range, i.e. is set with reference exhaust temperature Tex ₀ factory, the It determines that the reference exhaust temperature Tex _0, increase the proportion of the exhaust gas temperature Tex of the one of the cylinders is abnormal cylinder is present when it reaches the above certain ratio.
Alternatively, it is possible to determine that an abnormal cylinder exists when the absolute value of the exhaust temperature Tex in any cylinder exceeds the allowable value.

  In the exhaust temperature cylinder-to-cylinder variation determination unit 62, if there is a cylinder in which the shelf-injection is not normally performed, the exhaust temperature between the cylinders varies. Therefore, the exhaust temperature variation varies from the detected exhaust temperature value of each cylinder. If the amount of variation is equal to or greater than a certain value, it can be determined that there is a cylinder in which the shelf-equipped injection abnormality has occurred.

The above-described energization period increase determination unit 58, the exhaust temperature increase determination unit 60, or the exhaust temperature inter-cylinder variation determination unit 62, or by integrating the results of the plurality of determination units, the shelf-equipped injection is normally performed. If it is determined that it is not performed, the normal injection control is performed at the energization timing set by the abnormal-time energization timing setting means 44.
In the abnormal-time energization timing setting means 44, the abnormal-time energization timing map 66 is changed from the shelf-equipped injection to the normal injection timing and returned to the normal injection.
In the abnormality energization timing map 66, as shown in FIG. 6, θ1 which is the closing timing of the second solenoid valve 20 and θ2 which is the closing timing of the first solenoid valve 18 are set to the same timing in the pre-operation region. Has been.

  As described above, according to the present embodiment, the energization timing map 54 is used to switch between the shelf-equipped injection and the normal injection based on the engine speed Ne and the engine load Le, and the rack is operated in the middle rotation middle load region. Since switching is performed so as to perform supplementary injection, it is possible to achieve overall improvements in fuel efficiency, reduction of PM emissions, and reduction of NOx in the entire operation range.

  That is, in the high rotation and high load range, the fuel efficiency is more important than aiming at the exhaust gas purification function by the shelf-equipped injection, so that it is not suitable for the shelf-equipped injection. In the middle rotation / middle load range, NOx is actively reduced and the exhaust gas purifying function is exhibited, which is suitable for shelf-equipped injection. In the low rotation and low load range, the injection pressure is low and the injection pressure is further reduced by the shelf injection, so there is a concern about the increase in PM (particulate matter) discharge. Not suitable. In this way, in the entire driving range, it is possible to switch between the shelf-equipped injection and the normal injection so as to achieve overall improvement in fuel efficiency, reduction in PM emissions, and NOx reduction.

  In addition, if the shelf injection is not performed accurately at the time of the shelf injection, the fuel injection timing is substantially delayed, and the engine operation becomes unstable or unburned due to deterioration in fuel efficiency, exhaust temperature rise or misfire. In order to cause an adverse effect such as fuel discharge, when the shelf-equipped injection abnormality determining means 42 detects that there is a cylinder that is not performing fuel injection with a shelf, it is easy to use the abnormality energization timing map 66. By returning to normal injection, these adverse effects can be avoided, and the reliability of injection rate control with shelves can be improved.

  According to the present invention, the shelf-equipped injection and the normal injection are switched and operated based on the engine speed and the engine load. And improving fuel efficiency by improving combustion efficiency, and performing normal injection without shelves in an area where the injection rate control with shelves is not appropriate makes it possible to reduce NOx and improve fuel efficiency in the entire operating range. The PM reduction effect can be improved. Further, by detecting the abnormality when there is a cylinder for which the injection rate control with shelves is not reliably performed and performing the avoidance control, the injection rate control with shelves is performed. Since the reliability can be improved, it is suitable for use in a fuel injection device of a diesel engine.

2 Fuel injection device 4 Fuel injection valve 6 Injection pipe 8 Fuel tank 10 Delivery pipe 12 Fuel pump (fuel delivery means)
14 1st return pipe 16 2nd return pipe 18 1st solenoid valve (1st valve mechanism)
20 Second solenoid valve (second valve mechanism)
28 Aperture 38 Control device (switching control means)
40 Energization timing switching means 42 Shelf injection abnormality determination means 44 Abnormality energization timing setting means 50 Shelf injection control means 52 Normal injection control means 54 Energization timing map 58 Energization period increase determination section 60 Exhaust temperature rise determination section 62 Exhaust temperature cylinder Interval variation determination part 66 Abnormality energization timing map

Claims (5)

A fuel injection valve for injecting fuel; an injection pipe for guiding the fuel to the fuel injection valve; a fuel delivery means for sending fuel from a fuel tank to the injection pipe; and a fuel return means for returning the fuel from the injection pipe to the fuel tank. 1 and a second return pipe, a first valve mechanism for interrupting the first return pipe, and a second valve mechanism for interrupting the second return pipe,
The fuel flow rate when the first valve mechanism is opened is set to be smaller than the fuel flow rate when the second valve mechanism is opened;
When the fuel is supplied to the fuel injection valve, the second valve mechanism is closed and then the first valve mechanism is closed after a certain timing, and the fuel injection pressure injected from the fuel injection valve is equal to the fuel injection pressure for a certain period. A fuel injection rate control means for performing injection with a shelf that forms a shelf portion in which
The fuel injection rate control means has switching control means for switching between the shelf-equipped injection and the normal injection for simultaneously closing the first and second valve mechanisms based on the engine speed and the engine load. A fuel injection device.   2. The fuel injection device according to claim 1, wherein the switching control unit performs switching so as to perform the shelf-attached injection in an engine speed and load in a middle-rotation load region.   The fuel injection rate control means has shelf-equipped injection abnormality determining means for determining that there is a cylinder that is not performing shelf-attached injection during the operation of the shelf-attached injection, and the determining means uses the shelf-attached injection. The fuel injection device according to claim 1, wherein when it is determined that the fuel injection is not performed, the normal injection is restored.   The shelf injection abnormality determining means determines an abnormality of shelf injection based on an increase amount or an increase rate with respect to the closing period of the second valve mechanism at the time of engine shipment based on the closing period of the second valve mechanism. The fuel injection device according to claim 3.   The shelf-equipped injection abnormality determining means determines whether the shelf-equipped injection is abnormal based on a variation in exhaust temperature of each cylinder between cylinders or an increase amount or an increase rate with respect to the exhaust temperature at the time of engine shipment. Item 4. The fuel injection device according to Item 3.

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