JPS63289232A - Injection controller of accumulator fuel injection device for diesel engine - Google Patents

Abstract

PURPOSE:To make it possible to generate large output due to combustion of plenty of fuel after ignition by operating an injection starting command mean after fuel is pressed in an accumulator fuel injection device so as to open an ignited fuel injection starting command valve then open a main injection starting command valve. CONSTITUTION:In a device which has a fuel tank 1, a metering unit M and a unit injector U composed of a fuel injection pump 6 and an accumulator fuel injection device 7 and the like, are provided an injection starting command valve for ignition 21 and a decompression chamber for ignited fuel injection 22 which are arranged in the unit injector U, and an injection starting command mean 18 arranged in the metering unit M. Fuel for ignition is injected by means of that the command valve 21 is opened at the defined injection starting time and the inner pressure of an injection-valve closing pressure chamber 12 is depressurized to the decompression chamber 22 so as to open an injection valve 15. In addition, a main injection starting command valve 10 is opened after a defined ignition lag time and controlled so as to perform main fuel injection.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an injection control device for a pressure accumulation type fuel injection device for a diesel engine, and in particular, it is capable of preventing the occurrence of diesel knock without reducing output, and furthermore, The present invention relates to an injection timing control device for a pressure accumulation type fuel injection device for a diesel engine that is capable of increasing control accuracy of injection start timing.

<Prior art> In general, accumulator fuel injection devices for diesel engines are
For example, as shown in FIG. 1 or FIG. 6, the fuel injector includes an accumulator fuel injector 7 and a fuel supply system that supplies fuel thereto.

The pressure accumulation type fuel injector 7 is, for example, 700 to 1200
This is a fuel injector that injects fuel stored under high pressure such as atmospheric pressure, and as shown in FIGS. 1, 2, and 6, for example, it has a fuel inlet 11 that receives and receives fuel from the outside; It has a valve-closing pressure chamber 12, a check valve 13, a fuel pressure storage chamber 14, an injection valve 15, an injection hole 16, and a valve-closing spring 43, which are sequentially connected to this. The valve is configured to be biased to open by the internal pressure of the storage chamber 14, and biased to close by the biasing force of the valve-closing spring 43 and the internal pressure of the valve-closing pressure chamber 12. This fuel injection valve 15 is
With the injection valve 15 closed by the valve-closing spring 43 opposing the internal pressure of the fuel pressure storage chamber 14, high-pressure fuel of, for example, 700 to 1200 atmospheres is supplied from the fuel supply system to the fuel inlet 1.
1. After the fuel is pressurized into the fuel pressure storage chamber 14 through the valve-closing pressure chamber 12 and the check valve I3, the internal pressure of the valve-closing pressure chamber 12 is released to create a valve-opening force formed from the internal pressure of the fuel pressure storage chamber 14. The valve closing force made up of the internal pressure of the valve closing pressure chamber 12 and the biasing force of the valve closing spring 43 is weakened to open the injection valve 15, and the fuel in the fuel pressure storage chamber 14 is injected from the injection hole 16. It is composed of

The fuel supply system is configured to inject fuel into the accumulator fuel injector 7 at a high pressure as described above at a predetermined timing.
It is usually configured as follows. That is, the first
As shown in FIG. 6 and FIG. 6, fuel is pumped from a fuel tank 1 by a fuel pump (feed pump) 2, and the pressure of the pumped fuel is regulated by a pressure regulating device 3 in accordance with, for example, the engine rotation speed. Furthermore, the metering device 4 measures the fuel according to the load condition of the engine, and then the pressure pump (transfer pump) 5 pumps the fuel. The fuel is pressurized to a predetermined pressure or higher, such as atmospheric pressure, and then pressurized into the accumulator fuel injector 7. In addition, the fuel injection pump 6 is usually constituted by a plunger pump, and in order to prevent backflow to the pressure pump 5 side, an inlet valve 10 is provided on the upstream side of the pump chamber 9 where the plunger 8 goes in and out. The outlet side of 9 is the fuel inlet 11 of the pressure accumulator fuel injector 7.
connected to.

By the way, in the pressure accumulation type fuel injection device for a diesel engine configured as described above, the injection control device is configured to release the internal pressure of the valve closing pressure chamber 12 and open the injection valve 15 at a predetermined timing. is required.

Conventionally, the above-mentioned fuel injection pump 6 is also used as an injection control device for a pressure accumulation type fuel injection device for a diesel engine. That is, after accumulating fuel i+ in the high-pressure fuel injector 7, the plunger 8 is withdrawn from the pump chamber 9, thereby increasing the volume of the pump chamber 9 and transferring the internal pressure of the valve-closing pressure chamber 12 to the pump chamber 9. The valve opening biasing force of the injection valve 15 is reduced compared to the opening biasing force of the injection valve 15 to open the injection valve 15.

<Problems to be Solved by the Invention> In such a conventional fuel injection control device for a pressure accumulation type fuel injection device, in order to counter the internal pressure of the pump chamber 9 that the plunger 8 receives, a cam that drives the plunger 9 or a It is necessary to provide a relatively large contact area with the interlocking transmission mechanism. Therefore, it is difficult to form a cam profile that causes the plunger 8 to rise rapidly, and a large restriction is imposed on increasing the rate of rise of the plunger. Further, the inertia of the plunger 8 also imposes a certain limit on the rising speed of the plunger 8. The fact that the rising speed of the plunger 8 is limited means that the rate of expansion of the volume of the pump chamber 9 is greatly limited, and the gradient of the internal pressure in the valve-closing pressure chamber 12 cannot be made steeper than a certain level. In addition, the range of variation in control of the injection start timing increases due to some reason such as mechanical vibration due to impact between the drive device that drives the drive device or components within the drive device. Furthermore, while reducing the amount of fuel injected during the ignition delay period to prevent diesel knock,
After ignition, it is difficult to operate the plunger to inject a large amount of fuel and obtain a large output.

Therefore, as a result of intensive research, the present inventor has developed an injection control device ( (hereinafter referred to as "prior invention") was invented prior to the present invention.

That is, in this prior invention, as shown in FIG. 6, an injection start command valve (here, the large mouth valve 10 of the fuel injection pump 6 is also used) is provided in the valve closing pressure chamber 12 of the pressure accumulator fuel injector 7. injection start command means 1 for opening and closing the injection start command valve 10 at predetermined timing;
Technical measures have been taken to provide 8.

In this prior invention, the injection start command valve 1o is composed of a spool valve that is biased to close by the internal pressure of the flow path on the upstream side, and the injection start command means 18 is configured with a timing setting valve 19 that is interlocked with the crankshaft. , and a decompression chamber 20 connected to the flow path upstream of the injection start command valve 10 via this timing setting valve 19, and after pressurizing fuel from the fuel injection pump 6 into the pressure accumulation type fuel injector 7, By opening the timing setting valve 19 at the crankshaft angle, the flow path on the upstream side of the injection start command valve 10 and the pressure reduction chamber 20 are communicated, and the internal pressure in the flow path on the upstream side of the injection start command valve 10 is reduced. , the large mouth valve 10 serving as an injection start command valve is opened to reduce the internal pressure of the pump chamber 9 and the valve closing pressure chamber 12.

In this case, the injection start command means 18 opens the inlet valve 10 as the injection start command valve at a predetermined timing to reduce the internal pressure of the valve closing pressure chamber 12, so the valve closes more rapidly than in the conventional example described above. The internal pressure of the pressure chamber 12 can be reduced, which is more advantageous in increasing the speed of the engine, and by appropriately setting the shape of the valve hole of the large mouth valve 10 or the timing setting valve 19, it can be used as an injection start command valve. The opening amount of the large mouth valve IO is changed by the stroke of the spool, and the reduction of the internal pressure of the pump chamber 9 and the valve closing pressure chamber 12 is controlled over time. The fuel injection amount can be reduced by keeping the valve opening amount small, and the injection valve can be suddenly fully opened after ignition to inject a large amount of fuel within a short period of time. Therefore, while preventing diesel knock, it is also possible to inject a large amount of fuel after ignition to obtain high output.

In this prior invention, the inlet valve 10 of the fuel injection pump 6 as an injection start command valve is provided near the pressure accumulation type fuel injector 7, whereas the timing setting valve 19 is interlocked with the crankshaft. In order to simplify the mechanism, it is supported by the shaft end of the crankshaft (or a rotating shaft such as a valve train camshaft that is interlocked with the crankshaft) and is located quite far from the cylinder head to which the accumulator fuel injector 7 is attached. placed in position. Moreover, the pressure reduction chamber 20 is also disposed at a position away from the pressure accumulation type fuel injector 7, such as by being built into the timing setting valve 19, for example, in order to shorten the distance from the timing setting valve 19.

However, in this way, the closed valve pressure chamber 12 and the reduced pressure chamber 20
If the path length is long, the flow resistance between them will be large, and the gradient of the internal pressure reduction in the pump chamber 9, fuel inlet 11, and valve closing pressure chamber 12 after the injection start command valve 10 is opened will be relatively low. It has been found that the problem arises that the control becomes slow, the control sensitivity is relatively low, and the control of the opening timing of the injection valve 15 becomes large. Furthermore, it has been found that accurate fuel injection rate control is not possible in fuel injection rate control, which is disadvantageous in achieving both prevention of diesel knock and acquisition of high output.

The present invention has been made in consideration of the above circumstances, and is a pressure accumulator type for diesel engines that can prevent the occurrence of diesel knock without reducing the output, and can improve the control accuracy of the injection start timing. An object of the present invention is to provide an injection control device for a fuel injection device.

(Means for Solving the Problems) In the injection control device for a pressure accumulation type fuel injection device for a diesel engine according to the present invention, for example, as shown in FIGS. 1 to 3, the pressure accumulation type fuel injection device for a diesel engine A pressure accumulation type fuel injector 7 and a fuel supply system for supplying fuel thereto are provided. 13, a fuel pressure accumulation chamber 14, an injection valve 15, an injection hole 16, and a valve closing spring 43, and the injection valve 15 has a fuel pressure accumulation chamber 14, an injection valve 15, an injection hole 16, and a valve closing spring 43.
The valve is biased to open by the internal pressure of the valve IL 4, while the valve is biased to close by the biasing force of the valve closing spring 43 and the internal pressure of the valve closing pressure chamber 12, and fuel is supplied from the fuel supply system to the fuel population IL when the valve is closed. After the fuel is pressurized into the pressure storage chamber 14 through the pressure chamber 12 and the check valve 13, the internal pressure of the valve-closing pressure chamber 12 is released at a predetermined timing to open the valve-closing force of the injection valve 15. In an injection control device for a pressure accumulation type fuel injection device for a diesel engine configured to open the injection valve 15 with a force weaker than the valve biasing force, in order to achieve the above object, the pressure accumulation type fuel injector 7 is closed. The ignition injection start command valve 21 and the ignition fuel injection pressure reduction chamber 22 arranged close to the valve pressure chamber 12 are sequentially connected, while the main injection start command valve 10 and the main injection pressure reduction chamber 20 are closed. The ignition injection start command valve 21 is opened at a predetermined injection start time, and the internal pressure of the closed valve pressure chamber 12 is connected to the ignition fuel injection pressure reduction chamber 22.
The ignition fuel is injected by releasing the pressure and opening the injection valve 15, and when a predetermined time has elapsed from the opening of the ignition fuel injection start command valve 21, the main injection start command valve 1 is activated.
0 is opened, and the internal pressure of the closed valve pressure chamber 12 is transferred to the main injection pressure reducing chamber 2.
The present invention is characterized in that an injection start command means 18 is provided for injecting main fuel by opening the injection valve 15 by releasing the pressure.

The ignition injection start command valve 21 and the main injection start command valve 1
The type of valve 0 is not particularly limited, and it is also possible to use a spool valve. For example, a seat valve such as a poppet valve that can increase the rate of change in the valve opening amount or a needle valve that allows minute control of the valve opening amount can be used. It is possible to do so. Further, the injection start command valve 21, the main injection start command valve 10, and the fuel injection pump 6
However, as shown in FIGS. 2, 3, and 5, the inlet valve 10 of the fuel injection pump 6 can be provided independently from the main injection start command valve. It is advantageous for miniaturization to provide the main injection start command valve 10 and the ignition injection start command valve 21 integrally.

The injection start command means 18 can also be constituted by a mechanical mechanism interlocked with the crankshaft, but for example, as shown in FIG. 1, the injection start command valve 21 is biased to close by fluid pressure. A timing setting valve 19 composed of a spool valve and connected to the crankshaft in the same manner as the injection start command means 18 of the prior invention described above, and a timing setting valve 19 that closes the injection start command valve 21 through the timing setting valve 19. It is possible to configure the valve with a pressure reducing chamber 20 that reduces the pressure of the valve closing force by allowing fluid to flow therein. In this case, the decompression chamber 20 has both the function of the decompression chamber 20 of the injection start command means 18 and the function of the decompression chamber 20 for main injection.

According to the present invention configured as described above, after fuel is pressurized into the pressure accumulation type fuel injector, the injection start command means is operated at a predetermined timing to open the ignition injection start command valve. This causes the closed valve pressure chamber of the accumulator fuel injector to communicate with the ignited fuel injection pressure reducing chamber, and the internal pressure of the closed valve pressure chamber is relieved from the ignited fuel injection pressure reduced chamber, opening the injection valve. .

Here, since the ignition injection start command valve and the ignition fuel injection pressure reduction chamber are arranged close to the valve closing pressure chamber, the resistance of the flow path from the valve closing pressure chamber to the ignition fuel injection pressure reduction chamber 22 is small. , the pressure reduction gradient of the valve-closing pressure chamber becomes steeper, the control sensitivity becomes more sensitive, and the opening speed of the injection valve can be increased. Thereby, it is possible to reduce the variation in the opening start timing of the injection valve, and it is possible to improve the control accuracy of the injection start timing.

In addition, since the decompression chamber for ignition fuel injection is formed with a small volume, the amount of fuel injected for ignition fuel by opening the ignition injection start command valve is kept small, and by igniting a small amount of fuel, diesel Knocking can be prevented and driving noise can be reduced. On the other hand, since the main injection pressure reduction chamber is formed to have a large volume, the amount of fuel injected for main injection by opening the main injection start command valve can be increased. Since the time from the opening of the ignition injection start command valve 21 to the opening of the main injection start command valve 10 is set to a predetermined ignition delay time, a large amount of fuel is combusted after ignition, resulting in a large output. It is possible.

<Example> Hereinafter, an example of the present invention will be described based on FIGS. 1 to 4.

FIG. 1 is an equivalent circuit diagram of a pressure accumulator fuel injection device for a diesel engine according to the present invention, FIG. 2 is a longitudinal sectional view of a unit injector used in the fuel injection device in an initial state, and FIG. The figure is a longitudinal cross-sectional view of the essential parts of the unit injector when the injection 1;n start command valve is opened, and FIG. 4 is a timing diagram illustrating the operation of the unit injector and the injection start command means.

As shown in FIG. 1, this pressure accumulation type fuel injection device for a diesel engine includes a fuel tank 1, a metering unit M, and a unit injector U.

The metering unit M includes a fuel pump 2, a pressure regulating device 3, a metering device 4, and a pressure pump 5.

The unit injector U has an edge filter 27.
, a fuel injection pump 6 and an accumulator fuel injector 7 are incorporated.

The pressure accumulation type fuel injection device for a diesel engine further includes an injector m device that controls the fuel injection start timing and injection characteristics of the pressure accumulation type fuel injector 7, and this injection control device is configured as described below. metering unit M
and the unit injector U.

The fuel system that supplies fuel to the accumulator fuel injection pump 7 uses a pressure regulator 3 to regulate the pressure of the fuel pumped from the fuel tank 1 by the fuel pump 2 so that it increases or decreases in direct proportion to the engine speed. The amount of fuel supplied, whose pressure is regulated by the pressure device 3, is adjusted by the metering device 4 so as to increase or decrease in direct proportion to the engine load, for example, and then sent to the fuel injection pump 6 by the pressure pump 5 via the edge filter 27. The fuel is pressure-fed, raised to a high pressure of, for example, 700 to 1200 atmospheres by a fuel injection pump 6, and then pressurized into an accumulator fuel injector 7.

As shown in FIGS. 2 and 3, the fuel injection pump 6
is the upper surface of the body 23 of the unit injector U (second
A plunger 8 is inserted movably into a plunger insertion hole 24 recessed from the right side (in the figure), a pump chamber 9 partitioned by a plunger 8 at the lower part of the plunger insertion hole 24, and a large mouth valve 10. There is.

This artificial valve 10 can be provided independently of the plunger 8, but here it is built into the plunger 8 in order to downsize the unit injector U. That is,
A substantially cylindrical valve chamber 28 whose upper and lower ends are slightly enlarged in diameter is formed inside the plunger 8.
A spool 29 is slidably fitted inside. This spool 29 is formed into a hollow cylindrical shape with a closed upper end,
This hollow portion 32 is always connected to the edge filter 27 via an inlet passage portion 31 passing through an intermediate height portion of the circumferential wall of the spool 29 and an inlet passage portion 30 passing through an intermediate height portion of the circumferential wall of the plunger 8. (upstream side). The artificial valve 10 has a large mouth valve hole 33 formed in the lower half of the peripheral wall of the spool 29, and an outlet 34 formed in the lower half of the peripheral wall of the plunge +8, so that the spool 29 is slightly lower than the top dead center. When the large mouth valve hole 33 is located lower than a predetermined height, the large mouth valve hole 33 is communicated with the outlet 34 and opened, and the spool 29 is opened.
When the inlet valve hole 33 is located above this point, the inlet valve hole 33 is blocked from the outlet 34 and the valve is closed.

The valve chamber 28 is partitioned by a spool 29 into a valve opening pressure chamber 35 in its upper part and a pressure accumulation chamber 36 for plunger stroke adjustment in its lower part. The spool 29 is connected to a hollow portion 32 communicating with the upstream side of the inlet valve lO.
It is urged in the valve closing direction by the internal pressure P0 of the pressure accumulating chamber 36, and is urged in the valve opening direction by the internal pressure P0° of the valve opening pressure chamber 35.

Note that this valve opening pressure chamber 35 is communicated with the hollow portion 32 through a communication hole 37 formed in the upper part of the peripheral wall of the spool 29 when the spool 29 is located at the top dead center, and when the spool 29 is located at the bottom dead center. When located at a point, the plunger 8 is communicated with the hollow portion 32 through the communication hole 37 and a passage 38 formed in the upper part of the peripheral wall of the plunger 8.

An injection tube insertion hole 25 is formed in the body 23 of the unit injector U in parallel with the plunger insertion hole 24, and an injection tube 26 of the pressure accumulation type fuel injector 7 is fitted and supported in the injection tube insertion hole 25. .

In the lower half of the injection pipe 26, there is a valve closing pressure chamber 12, a check valve chamber 39, and a portion of the fuel pressure storage chamber 14.
The first fuel pressure accumulation chamber 14a (referred to as the fuel pressure accumulation chamber) 14a is vertically arranged coaxially and formed in a series, and the valve seat of the injection valve 15 is provided on the circumferential surface of the lower end (left end in FIG. 2) of the first fuel pressure accumulation chamber 14a. A surface 40 is formed.

The valve stem 42 of this injection valve 15 is connected to the first fuel pressure storage chamber 14a.
, check valve chamber 39 and valve closing pressure chamber 12! The upper end thereof is inserted into the valve-closing spring chamber 41 formed in the upper half of the injection pipe 26.

A valve body 13a of the check valve 13 is slidably fitted into a check valve chamber 39 interposed between the valve closing pressure chamber 12 and the first fuel accumulation injection chamber 14a, and this valve body 13a Valve seat 13b consists of an enlarged diameter portion formed at the middle height of the valve stem 41 of the injection valve 15
It is biased upward by the valve closing spring 13c. Therefore, the valve body 13a of this check valve 13 is connected to the valve closing pressure chamber 12.
The valve is urged to open by the internal pressure (=internal pressure p+ of the pump chamber 9), the valve is urged to close by the internal pressure Pt of the first fuel accumulation injection chamber 14a, and fuel is pressurized by the fuel injection pump 6 to close the valve pressure chamber 12. The internal pressure P of the first fuel accumulation injection chamber 14a is
The valve will be opened only when the

A valve-closing spring 43 is inserted into the valve-closing spring chamber 41 and biases the injection valve 15 in the valve-closing direction via the valve stem 42 .

Therefore, the injection valve 15 is urged in the valve-closing direction by the urging force of the valve-closing spring 43 and the internal pressure P of the valve-closing pressure chamber 12.
It is urged in the valve opening direction by the internal pressure P2 of the fuel pressure storage chamber 14a, and after the fuel supply from the fuel injection pump 6 is finished and the check valve 13 is closed, the internal pressure P1 of the valve closing pressure chamber 12 is reduced. When the above-mentioned valve-closing force becomes smaller than the above-mentioned valve-opening force, the valve is opened.

The upper end of the valve-closing spring chamber 41 is closed by a spring receiving seat 44 that sets the urging force of the valve-closing spring 43 and a valve-opening limiter 45 that sets the maximum opening amount of the injection valve 15. 4
The lower end of the valve 1 communicates with the valve-closing pressure chamber 35 of the artificial valve 10 via a pressure transmission path 46 and a passage 38 formed in the plunger 8 . Further, a spring seat 4 is provided at the upper end of the injection pipe 26.
A cap 47 that covers the valve opening limiter 4 and the valve opening limiter 4 is screwed on.
The space 4 formed between the valve opening limiter 45 and the valve opening limiter 45 communicates with the valve closing spring chamber 41 via a communication passage 49 connected to the valve opening limiter 45. By configuring in this way, camp 47
A space 48 formed between the spring receiving seat 44 and the valve opening limiter 45 is a pressure accumulator for stabilizing the opening pressure to absorb sudden pressure fluctuations in the opening pressure chamber 35 of the large mouth valve 10 together with the closing spring chamber 41. It will play the role of a room.

The remaining part of the fuel pressure storage chamber 14 (hereinafter referred to as the second fuel pressure storage chamber) 14b is formed in an annular shape over the middle height part of the injection pipe 26 and the part of the body 23 surrounding this. The fuel pressure storage chamber 14b has a check valve 5o.
and the first fuel pressure accumulation injection chamber 14a via the pressure setting valve 51.
connected to.

This check valve 50 prevents the internal pressure P of the first fuel pressure accumulation injection chamber 14a!
is the residual pressure in the second fuel pressure storage chamber 14b (for example, about 700
When the pressure becomes higher than the atmospheric pressure (atmospheric pressure), the valve is opened and fuel flows from the first fuel accumulation injection chamber 14a into the second fuel accumulation storage chamber 14b, and at the same time, a backflow from the second fuel accumulation injection chamber 14b to the first fuel accumulation injection chamber 14a occurs. is configured to prevent Further, the pressure setting valve 51 is connected to the second fuel pressure storage chamber 14.
When the internal pressure P of b increases to a predetermined residual pressure or higher, the valve opens to allow the flow of fuel between the second fuel pressure accumulation chamber 14b and the first fuel pressure accumulation injection chamber 14a, and the second fuel pressure accumulation chamber 14a is opened. Room 14b
When the internal pressure P of the second fuel pressure storage chamber 14b is reduced to a predetermined residual pressure, the internal pressure P of the second fuel accumulation storage chamber 14b.

The valve is closed so that the residual pressure does not fall below a predetermined residual pressure.

Now, as shown in FIG. 1, the injection control device includes an ignition injection start command valve 21 and an ignition fuel injection pressure reduction chamber 22 built into a unit injector U, and an injection start control valve built into a metering unit M. A command means 18 is provided.

As shown in FIGS. 2 and 3, the ignition injection start command valve 21 has a common valve chamber 2 with the large mouth valve 10 of the fuel injection pump 6.
8 and a spool 29.

That is, the ignition injection start command valve 21 includes an injection start pressure reduction passage 52 that connects the pump chamber 9 and the valve chamber 28 below the large mouth valve passage 34 of the peripheral wall of the plunger 8, and the artificial valve hole 33. It is composed of a valve groove 53 recessed all around the circumferential surface of the spool 29 below the spool 29, and is lower than the top dead center of the spool 29. When the spool 29 is located at a height within a predetermined range including
2 and the valve groove 53 are communicated with each other to open the valve.

The decompression chamber 22 for ignition fuel injection is formed between the inner peripheral surface of the plunger insertion hole 24 and the outer peripheral surface of the plunger 8 by recessing the outer peripheral surface of the peripheral wall portion of the plunger 8 facing the decompression passage 52 for starting injection. , and communicates with the valve chamber 28 via a pressure reduction passage 54 formed through a peripheral wall portion of the plunger 8 facing the injection start pressure reduction passage 52 .

This ignition fuel injection pressure reduction chamber 22 is connected to the pressure reduction passage 5 when the injection start pressure reduction passage 52 and the valve groove 53 are communicated with each other.
4. It is configured to communicate with the pump chamber 9 via a valve groove 53 and a pressure reduction passage 52 for starting injection.

Further, this ignition fuel injection decompression chamber 22 is always connected to a micro passage 60 formed in the peripheral wall of the plunger 8 and a spool 29.
The spool 29 is connected to the hollow portion 32 of the spool 29 through a communication passage 61 formed in the peripheral wall of the spool 29 .

As shown in FIG. 1, the injection start command means 18 includes a timing setting valve 19 sequentially connected upstream of the large mouth valve 1
and a decompression chamber 20, such that when the timing setting valve 19 is opened at a predetermined crankshaft angle in conjunction with a crankshaft (not shown), the depressurization chamber 20 is communicated with the upstream side of the large mouth valve IO. It has become. Furthermore, this timing setting valve 1
Reference numeral 9 denotes an advance angle control valve 19a that advances or delays the injection start timing in accordance with the engine speed, and a main timing setting valve that connects the advance angle control valve 19a and the inlet valve 10 within the advance angle range. 19b. The injection start command means 18 also includes a timing setting valve 1.
A discharge return passage 55 is provided in parallel with the discharge return passage 55 that connects the decompression chamber 20 and the large mouth valve 10, and the timing setting valve 19 that is once opened is shut off in this discharge return passage 55, and the timing setting valve 19 is cut off once the timing setting valve 19 is opened. The discharge return valve 56 is opened at the timing of
This is an intervention.

A fuel supply valve 57 is interposed between the pressure pump 5 of the fuel supply system and the edge filter 27, and between the outlet of the pressure regulator 3 of the fuel supply system and the edge filter 27, Pressure regulator 4, pressure pump 5, and fuel supply valve 5
An initial pressure adjustment pressure transmission path 58 connecting the outlet of the pressure adjustment device 3 to the upstream side of the edge filter 27 is connected in parallel with the pressure adjustment device 7 .

Interposed in this initial pressure adjustment pressure transmission path 58 is an on-off valve 59 that is opened when the fuel injection device returns to its initial state after the fuel injection ends.

The above-mentioned fuel supply valve 56, timing setting valve 19, discharge return valve 55, and on-off valve 58 may be provided separately, but since these valves are each opened and closed by a predetermined crankshaft, they are interlocked and connected to the crankshaft. It is possible to construct one composite timing control valve with a common rotary valve body.

Next, the operation of this fuel injection system will be described with a focus on the operations of the UNISOTO injector U and the injection control system.

+81 Initial state In the initial state, the fuel supply valve 57 and the timing setting valve 19
, the discharge return valve 55 and the on-off valve 58 are all closed,
As shown in FIG. 2, the plunger 8 of the fuel injection pump 6
is located at the top dead center, and the spool 29 is located at the bottom dead center. Therefore, the large mouth valve 10 is opened, and the ignition injection start command valve 21 is closed. Further, the check valve 13 is closed by a valve closing spring 13e, and the injection valve 15 is closed by a valve closing spring 43. Furthermore, the fuel injection pressure accumulation chamber 1
The check valve 49 and pressure setting valve 50 of No. 4 are both closed.

In the initial state, the valve opening pressure chamber 35, the valve closing spring chamber 41, and the cap 4 are connected to the hollow part 32 of the large mouth valve 10.
The internal pressure P of the space 48 in 7, ゛, the internal pressure Po of the pressure accumulation chamber 36,
The internal pressure P4 of the reduced pressure chamber 22 for ignition fuel injection, the internal pressure P of the pump chamber 9 and the valve closing pressure chamber 12 of the accumulator fuel injector 7 are equal to a predetermined initial pressure. The first downstream side of the check valve 13
The internal pressure P2 of the fuel accumulation chamber 14a is the residual pressure at the end of injection (
The internal pressure P3 of the second fuel pressure storage chamber 14b is equal to the closing pressure of the pressure setting valve 51 (for example, 700 atmospheres).

fbl Fuel supply to the injection pump 6 FIG. 4a where the supply of fuel to the fuel injection pump 6 is started
At a time point (hereinafter simply referred to as time point a, and each time point shown in FIG. 4 thereafter is also referred to in the same manner), the fuel supply valve 57 is switched from the closed state to the open state, and the pressure pump 5 is switched from the fuel injection pump 6 to the fuel injection pump 6. The pressure is regulated and the measured amount of fuel is pumped. This fuel is first applied to the artificial passage section 30, 31 and the hollow section 3.
2 into the pressure accumulation chamber 36, and moves the spool 29 to the top dead center side.

When the engine starts, is fully loaded, or is overloaded, the maximum amount of fuel is pumped from the pressure pump 5 and the spool 29
is moved to the top dead center, but at partial load, the spool 29 is moved to a position halfway between the bottom dead center and the top dead center, and the fuel supply starts at point b when the injection of fuel into the fuel injection pump 6 is completed. Valve 57 is closed.

At this point b, the internal pressure P3 of the pump chamber 9, the internal pressure P0 of the pressure accumulating chamber 36, and the internal pressure P,° of the valve opening pressure chamber 35 opposing the internal pressure Pa of the accumulating chamber 36 are higher than the initial pressure. , the pressure is lower than the internal pressure P2 of the first fuel injection pressure accumulation chamber 14a, and the check valve 13 is not opened.

(C1 Pressure injection of fuel into the pressure accumulator fuel injector 7 After this, the plunger 8 is pushed down from the top dead center by a cam (not shown) from time C to time i. Internal pressure P of the pump chamber 9
1 and the internal pressure P0 of the pressure accumulation chamber 36 are further increased from time C, the spool 29 is further raised and fuel is pressurized from the pump chamber 9 into the pressure accumulation chamber 36, and eventually, at time d, the spool 29 reaches a position near the top dead center. The inlet valve 10 rises to a predetermined height.
will be closed. After this time d, the internal pressure of the pump chamber 9 is P until the time i when the plunger 8 reaches the bottom dead center.
, is further increased, and the fuel in the pump chamber 9 is forced into the accumulator fuel injector 7.

Here, since the volume of the pressure accumulation chamber 36 expanded from time a to time d when the inlet valve 10 is closed is equal to the maximum injection amount, the pump chamber 36 increases from time C to time d. The amount of fuel pressurized into the pressure accumulator 36 from then on corresponds to the difference between the maximum injection amount and the amount of fuel supplied under pressure into the pressure accumulator 36 from time point a to time point b. In addition, the volume of the pump chamber 9 that is reduced when the plunger 8 moves from the top dead center to the bottom dead center is also equal to the maximum injection amount, so from time 4 until time i when the plunger 8 reaches the bottom dead center. The amount of fuel that is pressurized from the pump chamber 9 into the pressure accumulator fuel injector 7 is the amount of fuel that is injected from the pump 15 into the pressure accumulation chamber 3 between the maximum injection amount and time C to time e.
This corresponds to the difference between the amount of fuel pressurized into pump 6, that is, the amount of fuel supplied from pressure pump 5.

Incidentally, the decompression chamber 22 for ignition fuel injection from time a to time d
The internal pressure changes relatively slowly because the ignition fuel injection decompression chamber 22 is connected to the pump chamber 9 via the micro passage 60, the communication passage 61 hollow part 32, and the large mouth valve 10 before time d. The internal pressures P, , P of the pressure accumulation chamber 36 and the pump chamber 9 change in the same way.

After time 6, the internal pressure P in the pump chamber 9 and the valve-closing pressure chamber 12 rises rapidly, and this exceeds the internal pressure P2 in the first fuel accumulation chamber 14a from time 0 to time i when the plunger 8 reaches the bottom dead center. The check valve 13 is opened and fuel is pressurized into the first fuel pressure storage chamber 14a. Moreover, the fuel pressure P+(
Here, = P2) exceeds the set pressure of the pressure setting valve 51 h
At this point, the check valve 50 is opened and the first fuel pressure storage chamber 1 is opened.
Fuel is pressurized from 4a into the second fuel pressure storage chamber 14b.

The ignition injection start command valve 21 is opened before time d, and after the large mouth valve 10 is closed at time d, as the internal pressure P of the pump chamber 9 increases, the pressure from the pump chamber 9 increases. A very small amount of fuel leaks into the hollow part 32 of the spool 29 and the pressure accumulation chamber 36 through the ignition injection start command valve 21, the pressure reduction chamber 22 for ignition fuel injection, the micro passage 60, and the communication passage 61, and this fuel causes the pressure accumulation chamber to 36 and the internal pressure P of the hollow part 32. is slightly raised, and the spool 29 is further pushed up from the position at time d. The ignition injection start command valve 21 is closed at time f, just before the spool 29 reaches the top dead center.
After this, the process continues from the reduced pressure chamber 22 for ignited fuel injection to the micro passage 60 and the communication path 61 until the internal pressure P4 of the reduced pressure chamber 22 for ignited fuel injection becomes the same as the internal pressure P of the hollow part 32 and the pressure accumulation chamber 36.
Fuel flows into the hollow portion 32 of the spool 29 and the pressure accumulation chamber 36 through the spool 29 . This inflow pushes the spool 29 up to the top dead center.

The injection of fuel from the fuel injection pump 6 into the fuel injector 7 is terminated at time i when the plunger 8 reaches the bottom dead center, and each check valve 13, 50 is closed.

Td+ Fuel injection for ignition At a predetermined time point thereafter, the timing setting valve 19 of the injection start command means 18 is opened, and the decompression chamber 2° is communicated with the upstream side of the large mouth valve 10. As a result, the hollow part 3 of the large mouth valve 10
2 and the internal pressure of the pressure storage chamber 36 are reduced, the spool 29 begins to descend from the top dead center, and when the spool 29 has descended to a predetermined position slightly below the top dead center, the ignition injection start command valve 21 opens. be excused. Note that the control delay time from the opening of the timing setting valve 19 to the opening of the ignition injection start command valve 21 is as long as the initial pressure of the decompression chamber 20 (the internal pressure before the timing setting valve 19 opens) is constant. becomes constant. By opening the ignition injection start command valve 21, the internal pressure PI of the pump chamber 9 and the valve closing pressure chamber 12 is rapidly relieved to the ignition fuel injection pressure reduction chamber 22, and the internal pressure Pg of the first fuel pressure storage chamber 14a is
The injection valve 15 is opened at the 4th point in time when the valve-closing force consisting of the internal pressure P1 of the valve-closing pressure chamber 12 and the biasing force of the valve-closing spring 43 becomes weaker than the valve-opening force consisting of (-P at this point). .

What should be noted here is that by incorporating the ignition injection start command valve 21 and the ignition fuel injection pressure reduction chamber 22 into the plunger 8 of the fuel injection pump 6, the valve closing pressure chamber 12 of the accumulator fuel injector 7 Ignition injection start I command valve 2 connected sequentially
1 and the decompression chamber 22 for ignition fuel injection are arranged close to the valve closing pressure chamber 12 of the pressure accumulation type fuel injector 7, and the distance from the valve closing pressure chamber 12 to the decompression chamber 22 for ignition fuel injection is made as short as possible. It is that you are. By shortening the distance from the valve-closing pressure chamber 12 to the reduced pressure chamber 22 for ignition fuel injection, the resistance of the flow path from the ignition injection start command valve 21 to the reduced pressure chamber 22 for ignited fuel injection becomes smaller. Injection start command valve 21
The gradient of pressure reduction in the valve-closing pressure chamber 12 after the valve is opened can be made steep. As a result, the system? 11 sensitivity can be made more sensitive, the range of variation in the opening start timing of the injection valve 15 can be reduced, and the control precision of the injection start timing can be improved.

Since the pressure relief here is to the pressure reduction chamber 22 for ignition fuel injection, which has a relatively small volume, the amount of fuel that is relieved from the internal pressure P of the valve-closing pressure chamber 12 is relatively small. The opening amount of the injection valve 15 is also kept small, and the fuel injection rate is kept small. Internal pressure P of the pump chamber 9 and valve closing pressure chamber 12,
When the internal pressure P4 of the reduced pressure chamber 22 for ignited fuel injection becomes equal to the reduced pressure chamber 22 for ignited fuel injection and the hollow part 32, which are communicated with each other by the micro passage 60 and the communication path 61, the internal pressure PI (=P4) is gradually depressurized.

On the other hand, the first fuel pressure storage chamber 14 by fuel injection
The decrease in the internal pressure P2 of a is more rapid than the decrease in the internal pressure P1 of the valve-closing pressure chamber 12, and the difference between the valve-opening force and the valve-closing force becomes maximum m
From this point on, the opening amount of the injection valve 15 decreases, and eventually, at the point n, the injection valve 15 is temporarily closed and fuel injection is interrupted. n
When the injection valve 15 is closed at this point, the pressure reduction in the first fuel pressure storage chamber 14a stops, and as a result of the communication of the pressure setting valve 51, the fuel from the second fuel pressure storage chamber 14b flows into the first fuel pressure storage chamber 14a. The internal pressure P2 of the pressure accumulation chamber 14a increases again.

Fel Main fuel injection By the way, the pressure reduction of the internal pressure P0 of the hollow part 32 of the large mouth valve 10 and the pressure accumulating chamber 36 is performed continuously from time 3 until the internal pressure of the pressure reducing chamber 2° becomes equal to the internal pressure P0 of the pressure accumulating chamber. 29 is lowered almost independently of the fuel injection from time j to time n.

Then, at time 0 when the spool 29 has descended to a predetermined height lower than the top dead center, the large mouth valve 1o is opened and the pump chamber 9
and the valve closing pressure chamber 12 is the inlet valve 1o and the timing setting valve 1
It is connected to the decompression chamber 2o via 9. As a result, the internal pressure P of the pump chamber 9 and the valve closing pressure chamber 12 suddenly increases.
The pressure is significantly reduced, the injection valve 15 is suddenly and widely opened, and a large amount of high-pressure fuel is injected at once.

The time from time j when the spool 29 starts descending to the time when the ignition injection start command valve 21 is opened, and the large mouth valve lO is opened from time j. The time up to this point is determined by the flow path resistance from the large mouth valve lO to the decompression chamber 2o, and is therefore constant. Further, the time from time k to time 1 when fuel injection is started is constant because it is determined by the flow path resistance from the valve closing pressure chamber 12 to the reduced pressure chamber 22 for ignited fuel injection. Therefore, the time from time j when ignition injection starts to time 0 when main injection starts is constant regardless of the engine speed, and by setting this time equal to the ignition delay time, the ignition injection A small amount of injected fuel is ignited to prevent diesel knock and reduce engine operating noise, and a large amount of fuel is injected by main injection where the fuel injected by ignition injection ignites. It is now possible to obtain large output, making it possible to successfully prevent diesel knock and ensure high output.

After the artificial valve 10 is opened, the hollow part 32 of the large mouth valve 10
The internal pressure P0 of the pressure accumulating chamber 36 continues to be reduced, and the spool 29 continues to descend even after the zero point. Then, the ignition injection start command valve 21 is closed at time point p, which is a little after time point 0. After time 0, the fuel injection pressure is the same as the internal pressure P of the first fuel pressure storage chamber 14a, and is gradually reduced.

Then, at time q when the internal pressure P of the second fuel pressure storage chamber 14b is reduced to the set pressure of the pressure setting valve 51, the pressure setting valve 51 is closed, and after this time q, the first fuel pressure storage chamber 14a
The depressurization becomes even more rapid. The fuel injection rate is from time 0 to q
Up to this point, the fuel pressure rises because the high-pressure fuel flowing out from the second fuel pressure accumulation chamber 14b is injected, but after point q, the internal pressure P2 of the first fuel pressure accumulation chamber 14a decreases rapidly, and the fuel injection rate decreases. do. After the time point r when the internal pressure P2 of the first fuel pressure storage chamber 14a decreases due to the injection and the valve opening force becomes equal to the valve closing force, the internal pressure P of the first fuel pressure storage chamber 14a further increases due to the continued injection. As it continues to decrease,
The valve closing force becomes stronger than the valve opening force, and the injection valve 15 moves in the valve closing direction. Then, at time S when the internal pressure P2 of the first fuel pressure storage chamber 14a is reduced to a predetermined residual pressure, the injection valve 15 is closed and the fuel injection ends.

Note that the internal pressure P of the pump chamber 9 is 0 when the inlet valve lo is opened.
After that point, the pressure is rapidly and significantly reduced and becomes equal to the internal pressure P0 of the hollow portion 32 within a short period of time. Moreover, the internal pressure P4 of the decompression chamber 22 for ignition fuel injection is the same as the internal pressure P1 of the pump chamber 9 at time k, but rises very rapidly when the ignition injection start command valve 21 is opened at time k. , becomes the same as the internal pressure P of the pump chamber 9 within a short time. When the large mouth valve 10 opens at time 0, the internal pressure P of the pump chamber 9 and the internal pressure P4 of the decompression chamber 22 for ignition fuel injection drop rapidly, but the spool 29 becomes below a predetermined height and the ignition fuel injection After time point p when the injection start command valve 21 is closed, the communication between the decompression chamber 22 for ignited fuel injection and the pump chamber 9 is cut off, so the internal pressure P4 of the decompression chamber 22 for ignited fuel injection is changed from now on to the minute passage. 60 and the communication passage 61 into the hollow part 32, and eventually the internal pressure of the decompression chamber 22 for ignition fuel injection reaches the internal pressure Po of the hollow part 32 and the pump chamber 9.

It becomes the same as Pl. At this time, the pressure in the pressure accumulation chamber 36 is reduced to the pressure reduction chamber 20 from the sum of the maximum injection amount and the amount of fuel that has leaked from the pump chamber 9 to the pressure accumulation chamber 36 via the ignition fuel injection pressure reduction chamber 22 and the like. An amount of fuel corresponding to the amount of fuel remaining after deducting the amount of fuel remaining is left, and the spool 29 is positioned at a position higher than the bottom dead center.

(fl Return to initial state Ignition fuel injection decompression chamber 22, hollow part 32 and pump chamber 9
The plunger 8 of the fuel injection pump 6 begins to rise at a predetermined time t after the internal pressures Po, P+, and Pa become the same, and as the plunger 8 rises, fuel is sucked into the pump chamber 9 from the pressure accumulation chamber 36.

However, as described above, the amount of fuel stored in the pressure accumulation chamber 36 at time t is equal to the maximum injection amount. This amount corresponds to the amount obtained by subtracting the amount of fuel decompressed into the decompression chamber 20 from the amount added to the amount of the plunger 8.
It is insufficient to raise it to top dead center. Therefore, the discharge return valve 56 is opened for the time considered necessary for the plunger 8 to reach the cam base of the cam, that is, for one point from the point U, and the fuel depressurized into the decompression chamber 2o is transferred to the pressure accumulating chamber 36. This is to ensure that the plunger 8 returns to the top dead center. In addition, when the plunger 8 is returned to the top dead center at point 7 in this way, the pressure accumulation chamber is connected from the pump chamber 9 to the pump chamber 9 via the ignition fuel injection decompression chamber 22, etc. Since the fuel corresponding to the amount leaked to 36 is trapped in excess, these internal pressures are higher than the initial pressure at time 7. Therefore, by opening the initial pressure adjustment on-off valve 59 from a predetermined time W after time 1 to time X, the hollow part 32 of the large mouth valve 10, the pump chamber 9,
The internal pressures of the pressure accumulation chamber 36, the valve opening pressure chamber 35, the valve closing pressure chamber 12, and the ignition fuel injection pressure reduction chamber 22 are reduced to the initial pressure.

<Example 2> FIG. 5 is a vertical sectional view of the main part of another embodiment of the present invention.

In this embodiment, the ignition injection start command valve 21 is comprised of a double spool valve built into the plunger 8. That is, a child spool 62 is fitted into the lower end of the spool 29 so as to be movable up and down, and the child spool 62 has a through hole 63 whose diameter is reduced at the lower end, and a peripheral wall of a large diameter portion of the through hole 63 that faces each other. A valve hole 64 is formed.

Further, a valve groove 53 of the ignition injection start command valve 21 is formed on the outer peripheral surface of the peripheral wall of the reduced diameter portion of the through hole 63 over the entire circumference. On the other hand, a pair of valve holes 65 and 66 are formed in the peripheral wall of the lower end of the spool 29, which communicate with the valve groove 53 when the child spool 62 rises to the top dead center. is located at a height within a predetermined range slightly lower than top dead center, each valve hole 6 of the spool 29
An injection starting pressure reduction passage 52.5.4 communicating with the fuel injection valve 52.5.4 is formed. The rest of the configuration is the same as that of the above embodiment, so the explanation thereof will be omitted.

In this embodiment, when the valve opening start command means 1 day's timing setting valve 19 is opened to start depressurizing the hollow portion 32, fuel in the pressure accumulating chamber 36 is sucked into the depressurizing chamber 20 through the through hole 63. The spool 29 descends, but since the through hole 63 has a reduced diameter section, a pressure difference is created between the pressure accumulation chamber 36 and the hollow section 32, causing the child spool 62 to rise at the same time as the spool 29 descends. It will be done. Then, when the child spool 62 reaches the top dead center, the injection start pressure reducing passage 52 of the plunger 8.
54, 65 and 66 of the spool 29 and the valve 453 of the child spool 62 communicate with each other to open the ignition injection start command valve 21, and the pump chamber 9 communicates with the reduced pressure chamber 22 for ignition fuel injection to open the pump chamber 9. And the internal pressure of the valve-closing pressure chamber 12 is reduced.

The other operations are the same as those in the above embodiment, so the explanation thereof will be omitted.

<Effects of the Invention> As described above, according to the injection control device for a pressure accumulation type fuel injection device for a diesel engine according to the present invention, the valve opening command valve and the pressure reducing chamber for ignited fuel injection are arranged close to the closing valve pressure chamber. Therefore, the resistance of the flow path from the valve closing pressure chamber to the ignition fuel injection pressure reduction chamber is small, and the pressure reduction gradient of the valve closing pressure chamber becomes steep. As a result, the control sensitivity can be increased, and the range of variation in the opening start timing of the injection valve can be narrowed to improve the control accuracy of the injection start timing.

In addition, since the decompression chamber for ignition fuel injection is formed with a small volume, the amount of fuel injected for ignition fuel by opening the ignition injection start command valve is kept small, and by igniting a small amount of fuel, diesel Knocking can be prevented and driving noise can be reduced. On the other hand, since the decompression chamber 20 that functions as a depressurization chamber for main injection is formed with a large volume, in the main injection by opening the main injection start command valve, the opening amount of the injection valve is increased to reduce the fuel injection amount. Can be made in large quantities. Since the time from the opening of the ignition injection start command valve to the opening of the main injection start command valve is set to a predetermined ignition delay time, it is possible to obtain large output by burning a large amount of fuel after ignition. This makes it possible to successfully prevent diesel knock and ensure high output.

[Brief explanation of the drawing]

Fig. 1 is an equivalent circuit diagram of a pressure accumulator fuel injection device for a diesel engine according to the present invention, Fig. 2 is a vertical cross-sectional view of a unit injector used in the fuel injection device in its initial state, and Fig. 3 is an ignition type fuel injection device. FIG. 4 is a longitudinal cross-sectional view of the essential parts of the unit injector when the injection start command valve is opened, FIG. 4 is a timing diagram illustrating the operation of the unit injector and the injection start command means, and FIG. 5 is another embodiment of the present invention. FIG. 6, which is a vertical sectional view of the main part of the example, is an equivalent circuit diagram of the prior invention. 7... Pressure accumulation type fuel injector, IO... Large mouth valve (main injection start command valve), 11... Fuel inlet, 12... Valve closing pressure chamber, 13... Check valve, 14...・・Fuel accumulation storage chamber, 1
5... Injection valve, 16... Injection hole, 18... Injection start command means, 20... Pressure reduction chamber (main injection pressure reduction chamber), 2
DESCRIPTION OF SYMBOLS 1... Injection start command valve for ignition, 22... Pressure reduction chamber for ignition fuel injection, 43... Valve closing spring. Patent applicant: Kubota Iron Works Co., Ltd. 36 Crankshaft angle (θ)

Claims (1)

[Claims] 1. A pressure accumulation type fuel injection device for a diesel engine is provided with a pressure accumulation type fuel injector 7 and a fuel supply system that supplies fuel to the pressure accumulation type fuel injector 7. Valve pressure chamber 12, check valve 13, fuel accumulation storage chamber 14, injection valve 15, injection hole 16, and valve closing spring 4
3, the injection valve 15 is biased to open by the internal pressure of the fuel pressure storage chamber 14, and biased to close by the biasing force of the valve closing spring 43 and the internal pressure of the valve closing pressure chamber 12. The fuel is supplied from the fuel supply system to the fuel inlet 11 and the valve closing pressure chamber 12.
After the fuel is pressurized into the pressure storage chamber 14 via the check valve 13, the internal pressure of the valve-closing pressure chamber 12 is released at a predetermined timing, thereby changing the valve-closing force of the injection valve 15 to the valve-opening force. In an injection control device for a pressure accumulation type fuel injection device for a diesel engine, which is formed horizontally so as to open the injection valve 15 at a weaker level than that of The ignition injection start command valve 21 and the small volume ignition fuel injection pressure reduction chamber 22 are connected in sequence, while the main injection start command valve 10 and the large volume main injection pressure reduction chamber 20 are connected to the valve closing pressure chamber 12. are connected in order to open the ignition injection start command valve 21 at the start of a predetermined injection, relieve the internal pressure of the valve closing pressure chamber 12 to the ignition fuel injection pressure reduction chamber 22, and open the injection valve 15. By doing so, the ignition fuel is injected, and when a predetermined ignition delay time has elapsed from the opening of the ignition injection start command valve 21, the main injection start command valve 10 is opened to reduce the internal pressure of the valve closing pressure chamber 12. A pressure accumulation type fuel injection device for a diesel engine, characterized in that an injection start command means 18 is provided for injecting main fuel by depressurizing the main injection pressure reduction chamber 20 and opening the injection valve 15. injection control device