JPH05195903A - Fuel injection control device for diesel engine - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent adverse effects on the injection due to the lift position of the needle of the injection nozzle. [Structure] Oil feeding rate varying means 1 for varying the fuel feeding rate of fuel
A fuel injection device for a diesel engine, comprising: a fuel injection pump 2 having a fuel injection pump 2; and an injection nozzle 3 for injecting fuel in multiple stages by lifting a needle stepwise according to the pressure of fuel sent from the fuel injection pump 2. The oil feed rate control means 4 for controlling the fuel feed rate of the fuel of the injection pump 2 to a low oil feed rate in the low load range and to the high oil feed rate in the high load range, and an opening for detecting the lever opening of the fuel injection pump. Degree sensor 5, a rotation speed sensor 6 for detecting the rotation speed of the fuel injection pump or the engine, and area determination means 7 for determining an area where the lift amount of the needle of the injection nozzle 3 in the subsequent stage becomes small from these detection signals. A correction control means 8 is provided to relatively increase the fuel transfer rate of the fuel when it is in this region.

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 a diesel engine.

[0002]

2. Description of the Related Art Various fuel injection pumps and injection nozzles have been proposed in order to ensure good performance of diesel engines (Japanese Patent Laid-Open No. 61-218769, Sho 57-2).
5159, 63-168272, etc.).

As this fuel injection pump, there is a fuel injection pump which changes the fuel feed rate, and by changing the prestroke of the plunger of the pump and shifting the pressure feed section of the fuel, a low feed rate is achieved in the section where the plunger speed is slow. High oil transfer rate is obtained in the section where the plunger speed is high.

On the other hand, as the injection nozzle, a plurality of springs for urging the needle to close the valve are provided in parallel, and the first spring operates when the needle is in the initial lift (previous lift) stage, and in addition to this when the initial lift is exceeded. There is a multi-stage injection nozzle that injects the needle while gradually lifting the needle against the fuel pressure by lowering the initial injection rate by operating the second spring.

With such a fuel injection pump and injection nozzle, the fuel can be accurately ignited, the injection period of the fuel of the injection nozzle can be lengthened in the low load region of the engine, and NOx and HC can be reduced at the same time. .

In the high load and high speed range of the engine, a sufficient amount of fuel is injected from the injection nozzle within a limited period to improve the output performance.

[0007]

However, when the above-mentioned multi-stage injection nozzle is used, the lift position of the needle may affect the fuel injection.

That is, in the injection nozzle as described above, the fuel is completely injected into the low rotation region only by the lift of the front stage of the needle, but between this region and the high rotation region where the needle is sufficiently lifted in the rear stage, Sometimes the needle lifts slightly later.

Therefore, when the needle enters the valve closing position from the slight lift position, the front stage lift acts as a buffer region against the action of the spring, and the seating speed of the needle is reduced.

This is shown in FIG. 26 (oil feed rate variable) and FIG. 27 (oil feed rate fixed).

Therefore, the fuel consumption at the end of injection becomes worse, and smoke or the like may increase.

The present invention aims to solve such problems.

[0013]

The present invention, as shown in FIG. 1, has a fuel injection pump 2 having an oil feed rate varying means 1 for varying the fuel feed rate of fuel, and fuel sent from the fuel injection pump 2. In a fuel injection device of a diesel engine including an injection nozzle 3 for injecting fuel in multiple stages by gradually lifting a needle in accordance with the pressure of the fuel, the fuel injection rate of the fuel injection pump 2 is reduced to a low load region. The oil feed rate control means 4 for controlling the oil feed rate to a high oil feed rate in the high load range, the opening sensor 5 for detecting the lever opening of the fuel injection pump, and the rotational speed of the fuel injection pump or the engine are detected. The rotation speed sensor 6, a region determination means 7 for determining a region where the lift amount of the needle of the injection nozzle 3 in the latter stage of the injection nozzle 3 is small, and a fuel feed rate of the fuel relative to the region determination means 7 are relatively in the region. A correction control means 8 for increasing correction is provided. That.

Further, as shown in FIG. 1, an increment setting means 9 is provided for setting the increment of the oil feed rate according to the number of revolutions of the fuel injection pump 2.

Further, as shown in FIG. 2, the fuel injection pump 1 has an oil feed rate varying means 11 for varying the fuel feed rate of fuel.
2 and a fuel injection device for a diesel engine, which includes an injection nozzle 13 in which needles are lifted in stages according to the pressure of fuel sent from the fuel injection pump 12 to inject fuel in multiple stages. Oil feed rate control means 14 for controlling the oil feed rate to a low oil feed rate in the low load range and a high oil feed rate in the high load range, and a lift sensor for detecting the lift amount of the needle of the injection nozzle 13 or fuel A pressure sensor 15 for detecting the pressure, a lift determination means 16 for determining whether or not the lift amount of the subsequent stage of the needle has reached a predetermined value from this detection signal, and when the lift amount has not reached the predetermined value, the lift amount becomes a predetermined value. And a correction control means 17 for increasing and correcting the fuel feeding rate.

[0016]

In the region where the lift amount of the injection nozzle after the needle becomes small, or when the lift amount of the needle after the needle does not reach the predetermined value from the signal of the sensor that detects the lift amount of the needle or the fuel pressure, , Correct the oil feed rate to the increase side, that is, speed up the oil feed of the fuel injection pump to increase the fuel pressure and thereby increase the lift amount in the latter stage of the needle by a predetermined amount to ensure a quick seating speed of the needle. However, the influence on the fuel injection due to the position of the needle is prevented.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

First, FIG. 3 shows an example of the fuel injection pump 20, which is a so-called column type fuel injection pump (see Japanese Patent Laid-Open No. 61-218769), and the cam 21 driven synchronously with the engine. The rotation causes the plunger 22 to move up and down, and the fuel in the pressurizing chamber 23 is pressure-fed to the injection nozzle 40 via the fuel valve 24.

A control sleeve 25 is mounted around the plunger 22 as shown in FIG. 4, and the control sleeve 25 connects a fuel chamber 26 into which fuel is fed and a pressurizing chamber 23 with a passage 27 provided in the plunger 22. The suction port 28 to the fuel chamber 26 side is opened and closed.

As shown in FIGS. 5 and 6, when the plunger 22 rises with the lift of the cam 21 and the suction port 28 of the passage 27 is closed by the lower end of the sleeve 25, the communication with the fuel chamber 26 is cut off and added. The pressure in the pressure chamber 23 begins to increase, and the pressure feeding of fuel is started. Suction port 28
The plunger 22 has a prestroke until is closed.

Then, as shown in FIGS. 7 and 8, the plunger 22 further rises, and a spill port 30 provided with a groove 29 branching from the suction port 28 in the middle of the sleeve 25.
When the pressure chamber 23 communicates with the fuel chamber 26, the pressure chamber 23 communicates with the fuel chamber 26 again, and the pressure feeding of the fuel ends.

Since the branch groove 29 is opened as an inclined groove around the plunger, the rotation position around the axis of the plunger 22 is changed by the rotation control mechanism 31, so that the communication timing with respect to the spill port 30, that is, the end of the pressure feeding of the fuel. The timing can be changed and the fuel injection amount can be controlled.

On the other hand, the position control mechanism 32 can move the control sleeve 25 up and down. Further, the lift characteristic of the cam 21 is as shown in FIG. 9, and the speed of the plunger 22 increases as the lift speed increases.

As shown in FIG. 4, the position control mechanism 32 includes a drive rod 34 that engages with the control sleeve 25 via a pin 33.
And a rotary actuator 35. By rotating the drive rod 34, the control sleeve 25 moves up and down.

That is, the fuel pressure feeding speed can be changed by moving the position of the control sleeve 25 up and down by the position control mechanism 32 (oil feeding rate changing means). In this case, if the position of the control sleeve 25 is lowered, the plunger is moved. When the speed is slow, the fuel feed section becomes a low oil feed rate, and when the position of the control sleeve 25 is raised, when the plunger speed is fast, the fuel feed section becomes a high fuel feed rate.

Next, FIG. 10 shows an example of the injection nozzle 40 (see Japanese Patent Application No. 1-190460), in which a needle 42 is arranged inside a nozzle holder 41, and the needle 42 has first and second needles. The seats 45 are seated by the springs 43, 44 of.

When the pressure applied to the needle 42 rises above a predetermined pressure due to the fuel pressure from the fuel injection pump 20 introduced into the fuel pressure chamber 47, while compressing the first spring 43 via the push rod 46, Needle 4
2 is an initial lift (previous lift).

When the fuel pressure exceeds the set pressure of the second spring 44, the needle 42 is largely lifted (the latter lift is lifted) while the second spring 44 is compressed through the spring seat 48 in addition to the first spring 43. ) Do.

That is, when the increase in the fuel pressure is small, the fuel is injected by the front lift of the needle 42, and when the increase of the fuel pressure is large, a small amount of the initial injection is performed by the front lift of the needle 42. After being broken, a predetermined amount of fuel is injected by the subsequent lift.

According to the present invention, the controller (oil feed rate control means, area determination means, correction control means, increment setting means) 50 shown in FIG. 11 controls the fuel via the position control mechanism 32 based on the operating conditions. The oil feed rate of the injection pump 20 is controlled.

The controller 50 is a CPU of the arithmetic part,
A rotation speed sensor 51, which is composed of a ROM and a RAM of a storage portion, a microcomputer including an I / O of an input / output portion, and detects the rotation speed of the fuel injection pump 20 (or the rotation speed of the engine) via the I / O. Signal from the fuel injection pump 20
An opening signal from an opening sensor 52 that detects the lever opening (or the accelerator opening of the engine) is input.

As shown in FIG. 12, the controller 50 calculates the target oil feed rate from a predetermined data map set in advance based on the pump rotation speed from the rotation speed sensor 51 and the lever opening degree from the opening degree sensor 52. (Steps 101 to 10
3), the oil feed rate of the fuel injection pump 20 is controlled via the position control mechanism 32 so as to obtain the target oil feed rate (step 1).
04).

This target oil feed rate is basically a low oil feed rate in a low load range where the lever opening is small, a medium oil feed rate in a medium load range where the lever opening is medium, and a large lever opening. In the region where the oil feeding rate is set to be high in the high load region and the lift of the needle 42 of the injection nozzle 40 in the subsequent stage is slight, the amount is increased by a predetermined value as shown in FIG. 13 in accordance with the pump rotation speed. Set to the target oil transfer rate.

That is, the controller 50 basically obtains a low oil feeding rate in the low load area, a medium oil feeding rate in the medium load area, and a high oil feeding rate in the high load area according to the lever opening. As described above, while controlling the oil feed rate of the fuel injection pump 20 through the position control mechanism 32, the pump rotation speed and the lever opening degree are used to determine the region where the lift of the needle 42 of the injection nozzle 40 in the subsequent stage is slight, Even in the low load range, the medium oil feed rate is high in the region where the pump rotation speed is relatively high, the high oil feed rate is high in the medium load area where the pump rotation speed is relatively low, and the pump rotation speed is particularly high even in the high load area. In order to get the maximum oil transfer rate in the low region,
The feed rate of the fuel injection pump 20 is corrected and controlled via the position control mechanism 32.

In this case, since the increase in the oil feed rate is determined according to the pump rotation speed, an appropriate oil feed rate can be obtained.

The oil feed rate is divided into four from the low oil feed rate to the maximum oil feed rate, but it can be divided into more detailed sections in each area.

With this configuration, fuel is injected by the lift in the front stage of the needle 42 of the injection nozzle 40 in the low load and low rotation range of the engine, and by the lift in the front stage in the operation range where the load and rotation are high. After the initial injection, the needle 42 is largely lifted to the subsequent stage to inject a predetermined amount of fuel, while the fuel injection is not hindered in the region between them.

That is, in the region where the lift of the needle 42 of the injection nozzle 40 is small after the needle 42, the position control mechanism 32 corrects so as to relatively increase the oil feed rate of the fuel injection pump 20. Controlled. Therefore, the pressure of the fuel sent to the injection nozzle 40 increases, and the needle 42
The lift amount of the latter stage is expanded.

Therefore, when the needle 42 enters the valve closing state, the movement of the needle 42 does not slow down in the preceding lift section, and the repulsive force of the springs 44 and 43 causes the needle 42 to quickly seat (see FIG. 13). ) As a result, it is possible to maintain good fuel cutoff at the end of injection, ensure optimum injection, and reliably prevent the occurrence of smoke and the like.

14 to 16 show another embodiment of the present invention, in which the injection nozzle 40 is provided with a lift sensor 60 for directly detecting the lift amount of the needle 42.

As shown in FIG. 16, the controller (lift determining means, correction control means) 61 sets a target from a predetermined data map based on the pump rotation speed from the rotation speed sensor 51 and the lever opening degree from the opening degree sensor 52. The oil feed rate is calculated (steps 201 to 203), and the oil feed rate of the fuel injection pump 20 is controlled via the position control mechanism 32 so as to obtain the target oil feed rate (step 204). And measure the lift of the needle 42 (step 20
5) If the lift amount does not reach the predetermined value during the subsequent lift of the needle 42, the oil feed rate is increased (steps 206 to 208), and the position control mechanism is adjusted so that the lift amount reaches the predetermined value. The oil feed rate of the fuel injection pump 20 is corrected and controlled via 32.

That is, the maximum lift of the needle 42 is shown in FIG.
7, it is good in FIG. 19, but at the lift amount in FIG. 18, the oil feed rate is increased to increase the lift amount.

As described above, if the lift amount of the needle 42 is directly detected and corrected, more accurate control can be obtained, and the influence of the lift position of the needle 42 on the injection can be more reliably prevented.

Further, in this case, it is possible to cope with a difference in fuel property (viscosity) or a change in fuel temperature which affects the lift of the needle 42.

20 to 22 similarly show another embodiment of the present invention, in which a pressure sensor 70 for detecting the fuel pressure of the injection nozzle 40 is provided, and the lift state of the needle 42 is judged from the fuel pressure. is there.

The controller (lift determination means, correction control means) 71 uses a predetermined data map as a target based on the pump rotation speed from the rotation speed sensor 51 and the lever opening degree from the opening degree sensor 52 as shown in FIG. The oil feed rate is calculated (steps 301 to 303), the oil feed rate of the fuel injection pump 20 is controlled via the position control mechanism 32 so as to obtain the target oil feed rate (step 304), and the signal of the pressure sensor 70 is sent. The lift state of the needle 42 is determined from (step 30
5) When the lift of the needle 42 at the subsequent stage is under a pressure at which the lift does not reach the predetermined value, the oil feed rate is increased (steps 306 to 308), and the position control mechanism is adjusted so that the lift reaches the predetermined value. The oil feed rate of the fuel injection pump 20 is corrected and controlled via 32.

That is, the maximum fuel pressure is as shown in FIGS.
24 is good, but at the time of the pressure in FIG. 24, the oil feed rate is increased to increase the pressure and the lift amount of the needle 42 is expanded.

Also in this case, it is possible to cope with a difference in fuel property (viscosity) or a change in fuel temperature.

[0049]

As described above, according to the present invention, the fuel injection pump having the oil feeding rate changing means for varying the fuel feeding rate of the fuel, and the needle in a stepwise manner according to the pressure of the fuel fed from the fuel injection pump. In a fuel injection device of a diesel engine equipped with an injection nozzle that lifts and injects fuel in multiple stages, the fuel injection rate of the fuel injection pump is set to a low load range, a low oil transfer rate, and a high load range. Rate control means for controlling the fuel injection pump, an opening sensor for detecting the lever opening of the fuel injection pump, a rotation speed sensor for detecting the rotation speed of the fuel injection pump or the engine, and an injection nozzle of the injection nozzle based on these detection signals. Since the area determination means for determining the area where the lift amount after the needle becomes small and the correction control means for relatively increasing the fuel transfer rate when the area is in the area are provided, the fuel consumption may be changed depending on the operating range. In the jet of Without a cause, it is possible to ensure the always precise injection, it is possible to improve the engine performance.

Further, since the increase in the oil feed rate is set according to the number of revolutions of the fuel injection pump, the fuel injection can be controlled more accurately.

Further, the fuel injection pump having an oil feed rate varying means for varying the fuel feed rate, and the needle lifted stepwise in accordance with the pressure of the fuel sent from the fuel injection pump to inject the fuel in multiple stages. In a fuel injection device for a diesel engine equipped with an injection nozzle that operates, an oil feed rate control for controlling the fuel feed rate of a fuel injection pump to a low oil feed rate in a low load range and a high oil feed rate in a high load range Means, a lift sensor for detecting the lift amount of the needle of the injection nozzle or a pressure sensor for detecting the pressure of the fuel, and a lift determination means for determining whether or not the lift amount in the subsequent stage of the needle has reached a predetermined value from this detection signal. By providing correction control means for increasing and correcting the fuel feeding rate so that the lift amount becomes a predetermined value when the lift amount is not reached, it is possible to accurately grasp the lift position of the needle, Together accommodate Jo differences like can ensure a more proper injection of fuel.

[Brief description of drawings]

FIG. 1 is a configuration diagram of the present invention.

FIG. 2 is a configuration diagram of the present invention.

FIG. 3 is a sectional view of a fuel injection pump.

FIG. 4 is a perspective view of a main part of a fuel injection pump.

FIG. 5 is an operation explanatory view of a fuel injection pump.

FIG. 6 is an operation explanatory view of a fuel injection pump.

FIG. 7 is an operation explanatory view of a fuel injection pump.

FIG. 8 is an operation explanatory diagram of a fuel injection pump.

FIG. 9 is a cam lift characteristic diagram.

FIG. 10 is a sectional view of an injection nozzle.

FIG. 11 is a block diagram of a controller.

FIG. 12 is a flowchart of control operation.

FIG. 13 is a characteristic diagram showing an oil feed rate and a needle operation.

FIG. 14 is a cross-sectional view of an injection nozzle of another embodiment.

FIG. 15 is a block diagram of a controller.

FIG. 16 is a flowchart of control operation.

FIG. 17 is a control characteristic diagram of the needle.

FIG. 18 is a control characteristic diagram of a needle.

FIG. 19 is a control characteristic diagram of the needle.

FIG. 20 is a cross-sectional view of an injection nozzle of another embodiment.

FIG. 21 is a block diagram of a controller.

FIG. 22 is a flowchart of control operation.

FIG. 23 is a control characteristic diagram of the needle.

FIG. 24 is a control characteristic diagram of the needle.

FIG. 25 is a control characteristic diagram of the needle.

FIG. 26 is a needle operating characteristic diagram of a conventional example.

FIG. 27 is a needle operation characteristic diagram of a fixed oil feed rate in a conventional example.

[Explanation of symbols]

20 Fuel Injection Pump 21 Cam 22 Plunger 25 Control Sleeve 28 Suction Port 29 Groove 30 Spill Port 31 Rotation Control Mechanism 32 Position Control Mechanism (Oil Feed Rate Variable Means) 40 Injection Nozzle 42 Needle 43 Spring 44 Spring 50 Controller (Oil Feed Rate Control) Means, area determination means,
Correction control means, increment setting means) 51 rotation speed sensor 52 opening sensor 60 lift sensor 61 controller 70 pressure sensor 71 controller

Claims (3)

[Claims] 1. A fuel injection pump having an oil feed rate varying means for varying the fuel feed rate of fuel, and a needle lifted stepwise according to the pressure of the fuel sent from the fuel injection pump to inject fuel in multiple stages. In a fuel injection device for a diesel engine equipped with an injection nozzle that operates, an oil feed rate control for controlling the fuel feed rate of a fuel injection pump to a low oil feed rate in a low load range and a high oil feed rate in a high load range Means, an opening sensor for detecting the lever opening of the fuel injection pump, a rotation speed sensor for detecting the rotation speed of the fuel injection pump or the engine, and a lift amount in the subsequent stage of the needle of the injection nozzle is small from these detection signals. A fuel injection control device for a diesel engine, comprising: a region determination means for determining a region in which the fuel injection rate is increased, and a correction control device for relatively increasing and correcting the fuel feeding rate when in the region. 2. The fuel injection control device for a diesel engine according to claim 1, further comprising an increment setting means for setting an increment of the oil feed rate in accordance with a rotation speed of a fuel injection pump. 3. A fuel injection pump having an oil feed rate varying means for varying the fuel feed rate of fuel, and a needle lifted in stages according to the pressure of the fuel fed from the fuel injection pump to inject fuel in multiple stages. In a fuel injection device for a diesel engine equipped with an injection nozzle that operates, an oil feed rate control for controlling the fuel feed rate of a fuel injection pump to a low oil feed rate in a low load range and a high oil feed rate in a high load range Means, a lift sensor for detecting the lift amount of the needle of the injection nozzle, or a pressure sensor for detecting the pressure of the fuel, and a lift determination means for determining whether or not the lift amount in the subsequent stage of the needle has reached a predetermined value from this detection signal. A fuel injection control device for a diesel engine, further comprising: a correction control unit that increases and corrects a fuel feed rate so that the lift amount becomes a predetermined value when the lift amount is not reached.