JPH0633734B2 - Injection control device for accumulator fuel injection device for diesel engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection control device for a pressure-accumulation fuel injection device for a diesel engine, which is particularly advantageous for increasing the engine speed and has an injection start timing. The present invention relates to an injection timing control device for a pressure-accumulation fuel injection device for a diesel engine, which is capable of improving the control accuracy of.

<Prior Art> Generally, a pressure accumulating fuel injection device for a diesel engine is
For example, as shown in FIG. 1 or FIG. 6, a pressure accumulation type fuel injector 7 and a fuel supply system for supplying fuel to this are provided.

The pressure accumulation type fuel injector 7 is, for example, 700 to 1200.
A fuel injector for injecting fuel stored under a high pressure such as atmospheric pressure, and for example, as shown in FIG. 1, FIG. 2, and FIG.
And a valve closing pressure chamber 12, a check valve 13, which are sequentially connected to the
The fuel pressure storage chamber 14, the injection valve 15 and the injection hole 14 and the valve closing spring 43 are provided, and the injection valve 15 is biased by the biasing force of the valve closing spring 43 and the internal pressure of the valve closing pressure chamber 12 to close the valve. Meanwhile,
The valve is biased by the internal pressure of the fuel pressure accumulating chamber 14. The injection valve 15 is constructed by a valve closing spring 43 that opposes the internal pressure of the fuel pressure accumulating / storing chamber 14.
From the fuel supply system, for example, 700-
High-pressure fuel at 1200 atm, fuel inlet 11, closed valve pressure chamber 1
2 and the check valve 13 are pressed into the fuel pressure accumulating chamber 14 and then the internal pressure of the valve closing pressure chamber 12 is depressurized so that the valve closing force of the valve accumulating chamber 14 is less than the valve opening force of the internal pressure of the fuel accumulating chamber 14. 1
The valve closing force including the internal pressure of 2 and the biasing force of the valve closing spring 43 is weakened to open the injection valve 15 and inject fuel from the injection hole 16.

The fuel supply system is usually configured as follows in order to inject the fuel into the pressure-accumulation fuel injector at a predetermined timing at the high pressure as described above. That is, as shown in FIGS. 1 and 6, fuel is pumped from a fuel tank 1 by a fuel pump (feed pump) 2, and the pressure of the pumped fuel is adjusted by a pressure regulator 3 to correspond to, for example, the engine speed. Pressure is adjusted by the metering device 4 according to the load condition of the engine, and then the pressure pump (transfer pump)
5, the fuel discharged from the pressure-feeding pump 5 is pressurized by the fuel injection pump 6 to a high pressure of a predetermined pressure or higher such as 700 to 1200 atm, and is injected into the pressure-accumulation fuel injector 7. There is. Further, the fuel injection pump 6 is usually composed of a plunger pump, and is provided with an inlet valve 10 on the upstream side of a pump chamber 9 into and out of which the plunger 8 moves in and out in order to prevent a backflow to the pressure pump 5 side.
The outlet side of is connected to the fuel inlet 11 of the pressure accumulating fuel injector 7.

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

Conventionally, the fuel injection pump 6 is also used as an injection control device of a pressure-accumulation fuel injection device for a diesel engine. That is, after the fuel is stored in the pressure-accumulation fuel injector 7, the plunger 8 is withdrawn from the pump chamber 9 to increase the volume of the pump chamber 9 and release the internal pressure of the valve closing pressure chamber 12 to the pump chamber 9. The injection valve 15 is configured to open by making the valve closing biasing force weaker than the valve opening biasing force of the injection valve 15.

<Problems to be Solved by the Invention> In such a fuel injection control device for a conventional pressure-accumulation fuel injection device, a cam for driving the plunger 9 to counter the internal pressure of the pump chamber 9 received by the plunger 8 or a cam for driving the plunger 9 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, which imposes a great limitation in increasing the rate of rise of the plunger. Further, the inertia of the plunger 8 also gives a certain limit to the rising speed of the plunger 8. The restriction on the rising speed of the plunger 8 imposes a large restriction on the expansion rate of the volume of the pump chamber 9, and the pressure reduction gradient of the internal pressure of the valve closing pressure chamber 12 cannot be made steeper than a certain level. Further, the range of variation in control of the injection start timing caused by some reason such as mechanical vibration due to impact of the drive device for driving the same or components in the drive device becomes large.

Then, as a result of earnestly researching, the present inventor has solved such conventional problems and improved the control accuracy of the injection start timing control. Hereinafter, the invention is referred to as a 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 inlet valve 10 of the fuel injection pump 6 is also used) is provided in the valve closing pressure chamber 12 of the pressure accumulating fuel injector 7. Injection start command means 1 for connecting the pressure release passage 17 via the injection start command valve 10 and opening and closing the injection start command valve 10 at a predetermined timing.
The technical means of providing 8 is taken.

In this prior invention, the injection start command valve 10 is a spool valve that is biased to be closed by the internal pressure of the flow passage on the upstream side thereof, and the injection start command means 18 and a timing setting valve 19 linked to the crankshaft. A pressure reducing chamber 20 connected to the flow passage on the upstream side of the injection start command valve 10 via the timing setting valve 19, and after a predetermined amount of fuel is injected from the fuel injection pump 6 into the pressure accumulating fuel injector 7. By opening the timing setting valve 19 at the crankshaft angle, the flow passage on the upstream side of the injection start command valve 10 and the decompression chamber 20 are communicated with each other to reduce the internal pressure of the flow passage on the upstream side of the injection start command valve 10. The inlet valve 10 as the injection start command valve is opened to reduce the internal pressures 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 an injection start command valve at a predetermined timing to reduce the internal pressure of the valve closing pressure chamber 12, so that the valve is closed more rapidly than the conventional example. The internal pressure of the pressure chamber 12 can be reduced, which is more advantageous in increasing the speed of the engine, and by setting the shape of the valve hole of the inlet valve 10 or the timing setting valve 19 as an injection start command valve. The opening amount of the inlet valve 10 is changed by the stroke of the spool, and the pressure reduction of the internal pressure of the pump chamber 9 and the valve closing pressure chamber 12 is controlled with time, and the injection is performed within the post-ignition period from the start of injection to the ignition. It is possible to suppress the valve opening amount to a small amount and to inject a small amount of fuel, and rapidly open the injection valve after ignition so that a large amount of fuel can be injected within a short time.

In this prior invention, the inlet valve 10 of the fuel injection pump 6 as an injection start command valve is provided in the vicinity of the pressure accumulation type fuel injector 7, whereas the timing setting valve 19 is linked with the crankshaft. In order to simplify the mechanism, it is supported at the shaft end of the crank shaft (or a rotary shaft such as a valve cam shaft interlocked with the crank shaft) and is far from the cylinder head to which the pressure accumulating fuel injector 7 is mounted. It is located in a position. The decompression chamber 20 is also arranged at a position away from the pressure accumulation type fuel injector 7, for example, built in the timing setting valve 19 in order to shorten the distance from the timing setting valve 19.

However, in this way, the valve closing pressure chamber 12 to the decompression chamber 20
If the path length between the injection start command valve 10 and the pump chamber 9, the fuel inlet 11, and the valve closing pressure chamber 12 is relatively large, the flow passage resistance between them increases. In order to increase the control sensitivity, the injection valve 15
It was found that dissatisfaction still remains in improving the control accuracy by narrowing the range of variation in the valve opening start timing control.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an injection control device for a pressure-accumulation fuel injection device for a diesel engine, which is capable of improving the control accuracy of the injection start timing. It is a thing.

<Means for Solving Problems> An injection control device for a diesel engine pressure-accumulation fuel injection device according to the present invention is, for example, as shown in FIGS. 1 to 3, a diesel engine pressure-accumulation fuel injection device. Is provided with an accumulator fuel injector 7 and a fuel supply system for supplying fuel to the accumulator fuel injector 7, and the accumulator fuel injector 7 has a fuel inlet 11;
The valve closing pressure chamber 12, the check valve 13, the fuel pressure accumulating storage chamber 14, the injection valve 15 and the injection hole 16 and the valve closing spring 43, which are sequentially connected thereto, are provided, and the injection valve 15 is a fuel pressure accumulating storage chamber. 14
While the valve opening is biased by the internal pressure of the valve, the valve is biased by the biasing force of the valve closing spring 43 and the internal pressure of the valve closing pressure chamber 12, and the fuel is supplied from the fuel supply system to the fuel inlet 11 and the valve closing valve. After press-fitting into the fuel pressure accumulating 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 urging force of the injection valve 15. In order to achieve the above object, in the injection control device of the pressure-accumulation fuel injection device for a diesel engine configured to open the injection valve 15 by making it weaker than the valve biasing force, the pressure-accumulation fuel injector 7 is closed. An injection start command valve 21 and an injection start decompression chamber 22 arranged in the valve pressure chamber 12 in the immediate vicinity thereof.
Is sequentially connected, and injection start command means 18 for opening the injection start command valve 21 at the predetermined timing is provided.
The injection start command means 18 is operated at the predetermined timing to open the injection start command valve 21 to release the internal pressure of the valve closing pressure chamber 12 to the injection start decompression chamber 22. The means 18 includes a timing setting valve 19 and a pressure reducing chamber 20, and communicates the pressure reducing chamber 20 with the valve closing pressure chamber 12 through the timing setting valve 19 and the inlet valve 10 in order. It is characterized in that the valve 21 is opened at a timing when a predetermined time has elapsed from the valve opening timing, and the internal pressure of the valve closing pressure chamber 12 is released to the decompression chamber 20.

The type of the injection start command valve 21 is not particularly limited, and may be a spool valve, for example, a poppet valve that can increase the rate of change of the valve opening amount, a needle valve that allows easy minute control of the valve opening amount, and the like. It is possible to use a seat valve of. Although the injection start command valve 21 can be provided independently of the inlet valve 10 of the fuel injection pump 6, for example, as shown in FIG. 2, FIG. 3, and FIG. Providing it integrally with the inlet valve 10 of the pump 6 is advantageous for downsizing.

The injection start command means 18 can be constituted by a mechanical mechanism that is interlocked with the crankshaft, but, for example, as shown in FIG. 1, the injection start command valve 21 is biased to be closed by fluid pressure. A timing setting valve 19 which is composed of a spool valve and is interlocked with and connected to a crankshaft in the same manner as the injection start command means 18 of the preceding invention, and the injection start command valve 21 is closed and biased via this timing setting valve 19. It is possible to configure the decompression chamber 20 that decompresses the valve closing force by inflowing the fluid.

<Operation> According to the present invention configured as described above, after the fuel is injected into the pressure-accumulation fuel injector, the injection start command means is operated at a predetermined timing to open the injection start command valve to accumulate the pressure. The valve closing pressure chamber of the type fuel injector is communicated with the injection starting pressure reducing chamber, the internal pressure of the valve closing pressure chamber is reduced, and the injection valve is opened. Here, since the injection start command valve and the injection start pressure reducing chamber are arranged in the vicinity of the valve closing pressure chamber, the resistance of the flow path from the valve closing pressure chamber to the injection starting pressure reducing chamber is small,
The decompression gradient of the valve closing pressure chamber becomes steep, the control sensitivity can be made sensitive, and the variation range of the valve opening start timing of the injection valve can be narrowed to improve the control accuracy of the injection start timing.
Further, since the injection starting decompression chamber 22 has a small volume, the valve closing pressure chamber 12 has a relatively small pressure reduction width and is still maintained at a high pressure. On the other hand, the internal pressure of the fuel pressure accumulating / storing chamber 14 decreases with the fuel injection, the valve opening force of the injection valve 15 due to this internal pressure weakens, and the injection valve 15 is once closed. As a result, the fuel injection for ignition prior to the main injection ends.

The injection valve 15 is closed and the fuel injection is interrupted until a predetermined time elapses after the ignition fuel injection is completed.

When the predetermined time has elapsed, the inlet valve 10 is opened, the internal pressure of the valve closing pressure chamber 12 is released to the pressure reducing chamber 20, the valve closing force due to this internal pressure becomes weak, and the injection valve 15 stores the fuel pressure accumulation. It is pushed again by the valve opening force due to the internal pressure of the chamber 14, and the main fuel injection is started.

In this way, since fuel injection is not performed from once ignition fuel injection is completed until main fuel injection is started, the fuel injection amount during the ignition delay period can be small and the subsequent explosion The rate of pressure increase during the dynamic combustion period is low, and diesel knock is less likely to occur.

<Example 1> An example of the present invention will be described below with reference to Figs.

FIG. 1 is an equivalent circuit diagram of a pressure-accumulation fuel injection device for a diesel engine according to the present invention, and FIG. 2 is a vertical cross-sectional view of a unit injector used in the fuel injection device in an initial state. FIG. 4 is a longitudinal sectional view of a main part of the unit injector when the injection start command valve is opened, and FIG. 4 is a timing diagram for explaining the operation of the unit injector and the injection start command means.

As shown in FIG. 1, the 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 regulator 3, a metering device 4, and a pressure pump 5.

The unit injector U includes an edge filter 2
7, a fuel injection pump 6 and a pressure accumulating fuel injector 7 are incorporated.

The pressure-accumulation fuel injection device for a diesel engine further includes an injection control device that controls the fuel injection start timing and injection characteristics of the pressure-accumulation fuel injector 7, and this injection control device will be described later. It is provided across the metering unit M and the unit injector U.

The fuel system for supplying fuel to the pressure-accumulation fuel injection pump 7 regulates the pressure of the fuel pumped from the fuel tank 1 by the fuel pump 2 by the pressure regulator 3 so as to increase or decrease in direct proportion to the engine speed, for example. The amount of fuel supplied by the pressure device 3 is adjusted by the amount adjusting device 4 so as to be increased or decreased in direct proportion to, for example, the load of the engine, and then the pressure pump 5 supplies the fuel injection pump 6 via the edge filter 27. It is configured to be pressure-fed, to be pressurized to a high pressure of, for example, 700 to 1200 atm by the fuel injection pump 6, and to be press-fitted into the pressure accumulating fuel injector 7.

As shown in FIG. 2 and FIG. 3, the fuel injection pump 6 is
Is the upper surface of the body 23 of the unit injector U (second
The plunger 8 is inserted into a plunger insertion hole 24 recessed from the right side in the figure) so as to be able to move forward and backward, a pump chamber 9 defined by the plunger 8 at the lower part of the plunger insertion hole 24, and an inlet valve 10. .

The inlet valve 10 can be provided independently of the plunger 8, but here it is built in the plunger 8 in order to reduce the size of the unit injector U. That is,
Inside the plunger 8, a substantially cylindrical valve chamber 28 whose upper end and lower end are slightly expanded in diameter is formed.
A spool 29 is slidably fitted therein. This spool 29 is formed into a hollow cylindrical shape with the upper end closed,
The hollow portion 32 is always on the side of the edge filter 27 via an inlet passage portion 31 that penetrates a portion of the spool 29 at an intermediate height of the peripheral wall and an inlet passage portion 30 that penetrates a portion of the peripheral wall of the plunger 8 at an intermediate height. It is connected to (upstream side). The inlet valve 10 includes an inlet valve hole 33 formed in the lower half portion of the peripheral wall of the spool 29 and an outlet 34 formed in the lower half portion of the peripheral wall of the plunger 8, so that the spool 29 is slightly smaller than the top dead center. The inlet valve hole 33 communicates with the outlet 34 to open the valve when it is positioned lower than a predetermined low height.
Is positioned above that, the inlet valve hole 33 is blocked from the outlet 34 and closed.

Inside the valve chamber 28, a valve opening pressure chamber 35 is defined at the upper part thereof, and a pressure storage chamber 36 for adjusting the plunger stroke is partitioned at the lower part thereof by a spool 29. The spool 29 has a hollow portion 32 that communicates with the upstream side of the inlet valve 10.
And the internal pressure P ₀ of the pressure accumulating chamber 36 biases the valve in the valve closing direction, and the internal pressure P ₀ ′ of the valve opening pressure chamber 35 biases the valve in the valve opening direction. When the spool 29 is located at the top dead center, the valve opening pressure chamber 35 is communicated with the hollow portion 32 by the communication hole 37 formed in the upper portion of the peripheral wall of the spool 29, and the spool 29 is bottom dead. When located at a point, the communication hole 37 and the passage 3 formed in the upper part of the peripheral wall of the plunger 8
And 8 to communicate with the hollow portion 32.

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

In the lower half portion of the injection pipe 26, the valve closing pressure chamber 12, the check valve chamber 39, and a part of the fuel pressure accumulating chamber 14 (hereinafter referred to as the first
A fuel pressure accumulating chamber) 14a are coaxially arranged in the vertical direction and are formed in series, and the valve seat of the injection valve 15 is formed on the peripheral surface of the lower end portion (left end in FIG. 2) of the first fuel pressure accumulating chamber 14a. A surface 40 is formed.

The valve stem 42 of the injection valve 15 is the first fuel pressure accumulating storage chamber 14
a, the check valve chamber 39 and the valve closing pressure chamber 12 are penetrated, and the upper end portion thereof is further projected into the valve closing spring chamber 41 formed in the upper half portion of the injection pipe 26.

The valve body 13a of the check valve 13 is slidably fitted in the check valve chamber 39 interposed between the valve closing pressure chamber 12 and the first fuel pressure accumulating injection chamber 14a. A valve seat 13b formed of an enlarged diameter portion formed at an intermediate height of the valve stem 41 of the injection valve 15.
The valve closing spring 13c is urged upward toward. Therefore, the valve body 13a of the check valve 13 is closed by the valve closing pressure chamber 1
The valve opening is energized by the internal pressure of 2 (= the internal pressure P ₁ of the pump chamber 9),
The internal pressure P _{2 of} the first fuel pressure accumulating injection chamber 14a is biased to close the valve, and the fuel is injected by the fuel injection pump 6 so that the internal pressure P ₁ of the valve closing pressure chamber 12 becomes the internal pressure P of the first fuel pressure accumulating injection chamber 14a.
Only when the number exceeds ₂ , the valve will be opened.

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

Therefore, the injection valve 1 is biased in the valve closing direction by the biasing force of the valve closing spring 43 and the internal pressure P ₁ of the valve closing pressure chamber 12, and is opened by the internal pressure P _{2 of} the first fuel pressure accumulating storage chamber 14a. After being energized, the fuel supply from the fuel injection pump 6 is completed and the check valve 13 is closed, the internal pressure P ₁ of the valve closing pressure chamber 12 is reduced and the above-mentioned valve closing force is opened. If it becomes smaller than the force, it will be opened.

The upper end of the valve closing spring chamber 41 is closed by a spring seat 44 that sets the urging force of the valve closing spring 43 and a valve opening restrictor 45 that sets the maximum valve opening amount of the injection valve 15. Four
The lower end of 1 is communicated with the valve closing pressure chamber 35 of the inlet valve 10 via a pressure transmission passage 46 and a passage 38 formed in the plunger 8. Further, the spring seat 4 is provided at the upper end of the injection pipe 26.
4 and the valve opening limiter 45 are screwed together, and the cap 47, the spring seat 44, and the valve opening limiter 4 are screwed together.
A space 48 formed between the valve closing spring chamber 41 and the valve opening 5 is communicated with the valve closing spring chamber 41 through a communication passage 49 provided in the valve opening restrictor 45. With this configuration, the cap 47
The space 48 formed between the valve seat 44 and the valve seat 44 and the valve opening restrictor 45 absorbs a sudden pressure fluctuation in the valve opening pressure chamber 35 of the inlet valve 10 together with the valve closing spring chamber 41. Will play the role of a room.

The remaining portion of the fuel pressure accumulating chamber 14 (hereinafter referred to as the second fuel pressure accumulating chamber) 14b is formed in an annular shape over the intermediate height portion of the injection pipe 26 and the portion of the body 23 around this portion. The fuel pressure accumulation chamber 14b is connected to the first fuel pressure accumulation injection chamber 14a via a check valve 50 and a pressure setting valve 51.

The check valve 50 is provided with an internal pressure P ₂ of the first fuel pressure accumulating injection chamber 14a.
Is the residual pressure of the second fuel pressure accumulating storage chamber 14b (for example, about 700
If the pressure becomes higher than (atmospheric pressure), the valve is opened to allow the fuel to flow from the first fuel pressure accumulating / storing chamber 14a into the second fuel pressure accumulating / storing chamber 14b and from the second fuel pressure accumulating / storing chamber 14b to the first fuel pressure accumulating / injecting chamber 14a. It is configured to block backflow. Further, the pressure setting valve 51 is used for the second fuel pressure accumulating storage chamber 1
When the internal pressure P _{3 of} 4b rises above a predetermined residual pressure, the valve is opened to open the second fuel pressure storage chamber 14b and the first fuel pressure injection chamber 14a.
Is allowed to flow between the second fuel pressure accumulating and storing chamber 14 and
b internal pressure P ₃ of the is adapted to the internal pressure P ₃ of the is reduced to a predetermined residual pressure second fuel accumulator reservoir 14b is closed so as not to fall below a predetermined residual pressure.

Now, as shown in FIG. 1, the injection control device has an injection start command valve 2 incorporated in the unit injector U.
1 and an injection start decompression chamber 22, and an injection start command means 18 incorporated in the metering unit M.

The injection start command valve 21 has a valve chamber 28 and a spool 29 which are common to the inlet valve 10 of the fuel injection pump 6, as shown in FIGS. 2 and 3. That is, the injection start command valve 21 is provided below the inlet valve passage 34 on the peripheral wall of the plunger 8 and below the inlet valve passage 34 for communicating the pump chamber 9 with the valve chamber 28, and the inlet valve hole 33. It is composed of a valve groove 53 that is recessed all around the circumference of the lower spool 29, and is lower than the top dead center of the spool 29.
When the spool 29 is positioned at a height within a predetermined range including the position of the spool 29 at which the inlet valve 10 is opened and closed, the injection start depressurizing passage 52 and the valve groove 53 are communicated with each other and opened. Made of

The injection starting decompression chamber 22 includes an injection starting decompression passage 52.
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
2 is communicated with the valve chamber 28 via a pressure reducing passage 54 formed through the peripheral wall portion of the plunger 8 facing the valve 2. The injection start decompression chamber 22 is provided in the injection start decompression passage 5
When the 2 and the valve groove 53 are communicated with each other, they are communicated with the pump chamber 9 through the pressure reducing passage 54, the valve groove 53 and the injection starting pressure reducing passage 52. Further, the injection-starting decompression chamber 22 is always provided with a minute passage 60 formed on the peripheral wall of the plunger 8 and a communication passage 61 formed on the peripheral wall of the spool 29.
It is adapted to communicate with the hollow portion 32 of the spool 29 via.

As shown in FIG. 1, the injection start command means 18 includes a timing setting valve 19 and a pressure reducing chamber 20 which are sequentially connected to the upstream side of the inlet valve 10, and the timing setting valve 19 is linked to a crankshaft (not shown). The pressure reducing chamber 20 is communicated with the upstream side of the inlet valve 10 when the valve is opened at a predetermined crankshaft angle. The timing setting valve 19
Is an advance control valve 19a for advancing or delaying the injection start timing according to the engine speed, and a main timing setting valve 19b for connecting the advance control valve 19a and the inlet valve 10 within the advance range. It consists of and. Also,
The injection start command means 18 includes a timing setting valve 19
A discharge return passage 55 that connects the decompression chamber 20 and the inlet valve 10 is provided in parallel with the discharge return passage 55. The discharge return passage 55 shuts off the timing setting valve 19 that was once opened, and a predetermined period after the fuel injection is completed. A discharge return valve 56 that is opened at a timing is interposed.

A fuel supply valve 57 is interposed between the pressure feed 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
A pressure transmission path 58 for initial pressure adjustment, which connects the outlet of the pressure regulator 3 to the upstream side of the edge filter 27, is connected in parallel with 7. An on-off valve 59 that is opened when the fuel injection ends and the fuel injection device returns to the initial state is interposed in the initial pressure adjusting pressure transmission path 58.

The fuel supply valve 56, the timing setting valve 19, the discharge return valve 55, and the opening / closing valve 58 may be separately provided, but since these valves are opened and closed by a predetermined crankshaft, they are interlocked with the crankshaft. It is possible to configure as one combined timing control valve having a common rotary valve body.

Next, the operation of the fuel injection device will be described focusing on the operation of the unit injector U and the injection control device.

(a) Initial state In the initial state, the fuel supply valve 57 and the timing setting valve 1
9, the discharge valve 55 and the open / close valve 58 are all closed, and 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 inlet valve 10 is opened and the injection start command valve 21 is closed. Further, the check valve 13 is the closing spring 1
The injection valve 15 is closed by the valve closing spring 43. Further, both the check valve 49 and the pressure setting valve 50 of the fuel injection pressure accumulating chamber 14 are closed.

Further, in the initial state, the valve opening pressure chamber 35, the valve closing spring chamber 41 and the cap 47, which communicate with the hollow portion 32 of the inlet valve 10.
Pressure P ₀ of the space 48 of the inner ', the internal pressure _{P 0} of the accumulator 36, the internal pressure _{P 4} of the injection start pressure reducing chamber 22, the internal pressure _{P 1} of the closing chamber 12 of the pump chamber 9 and an accumulator fuel injector 7 Equal to the predetermined initial pressure. The internal pressure P ₂ of the first fuel pressure accumulation storage chamber 14a on the downstream side of the check valve 13 is equal to the residual pressure at the end of injection (the internal pressure when the injection valve 15 is closed), and the second fuel pressure accumulation storage chamber 1
The internal pressure P ₃ of 4b is the closing pressure of the pressure setting valve 51 (for example, 70
0 atm).

(b) Fuel supply to the injection pump 6 Fuel supply to the fuel injection pump 6 is started FIG. 4a
At a time point (hereinafter, simply referred to as time point a and the same applies to each time point shown in FIG. 4 thereafter), the fuel supply valve 57 is switched from the closed state to the open state, and the pressure feed pump 5 changes from the fuel injection pump 6 to the fuel injection pump 6. The regulated and regulated fuel is pumped. First, the fuel is introduced into the inlet passage portions 30, 31 and the hollow portion 32.
Is press-fitted into the pressure accumulating chamber 36 via the, and the spool 29 is moved to the top dead center side.

When the engine is started, at the time of full load or at the time of overload, the maximum injection amount of fuel is pressure-fed from the pressure-feed pump 5 and the spool 29
Is moved to the top dead center, but the spool 29 is moved to a position intermediate between the bottom dead center and the top dead center at the time of partial load, and the fuel is supplied at time b when the injection of fuel into the fuel injection pump 6 is completed. The valve 57 is closed.

At this time point b, the internal pressure P ₁ of the pump chamber 9, the internal pressure P ₀ of the pressure accumulating chamber 36, and the internal pressure P ₀ ′ of the valve opening pressure chamber 35, which opposes the internal pressure P ₀ of the pressure accumulating chamber 36, are higher than the initial pressure. However, the internal pressure P _{2 of} the first fuel injection pressure accumulating chamber 14a is lower than the internal pressure P ₂ , and the check valve 13 does not open.

(c) Fuel injection into the pressure-accumulation fuel injector 7 From time c to time i after this, the plunger 8 is pushed down from the top dead center by a cam not shown. The internal pressure P ₁ of the pump chamber 9 and the internal pressure P ₀ of the pressure accumulating chamber 36 are further increased from the time point c, the spool 29 is further raised, and the fuel is pressed from the pump chamber 9 into the pressure accumulating chamber 36, and eventually d.
At that time, the spool 29 is raised to a predetermined height near the top dead center and the inlet valve 10 is closed. After the time point d, the internal pressure P ₁ of the pump chamber 9 is further increased until the time point i when the plunger 8 reaches the bottom dead center, and the fuel in the pump chamber 9 is pressed into the pressure accumulating fuel injector 7. .

Here, since the volume of the pressure accumulating chamber 36 that is expanded from the time point a to the time point d when the inlet valve 10 is closed is made equal to the maximum injection amount, the pump chamber 9 is changed from the time point c to the time point d. The amount of fuel injected into the pressure accumulating chamber 36 corresponds to the difference between the maximum injection amount and the amount of fuel supplied into the pressure accumulating chamber 36 from the time point a to the time point b. Further, since the volume of the pump chamber 9 which is reduced by moving the plunger 8 from the top dead center to the bottom dead center is equal to the maximum injection amount, after the time point d until the time point i when the plunger 8 reaches the bottom dead point. The amount of fuel injected into the accumulator fuel injector 7 from the pump chamber 9 is the maximum injection amount and from the pump 15 to the accumulator chamber 3 between the time point c and the time point e.
It corresponds to the difference from the amount of fuel press-fitted into 6, that is, the amount of fuel supplied from the pressure feed pump 5.

In addition, the internal pressure of the injection start decompression chamber 22 from the time point a to the time point d is the same as that of the minute passage 6 before the time point d.
0, the communication passage 61 communicates with the pump chamber 9 through the hollow portion 32 and the inlet valve 10, so that the internal pressures P ₀ and P ₁ of the pressure accumulating chamber 36 and the pump chamber 9 that change relatively slowly change. To do.

After the time point d, the internal pressure P ₁ of the pump chamber 9 and the valve closing pressure chamber 12 rapidly increases, and exceeds the internal pressure P ₂ of the first fuel pressure accumulating and storing chamber 14a from the time point e, the time point i when the plunger 8 reaches the bottom dead center. The check valve 13 is opened over, and the fuel is press-fitted into the first fuel pressure accumulating storage chamber 14a. Further, the fuel pressure P from the pump chamber 9 to the first fuel pressure accumulating and storing chamber 14a
₁ h time point exceeding the set pressure of the _(here = P ₂₎ pressure setting valve 51, the fuel pressed from the first fuel accumulator storage chamber 14a check valve 50 is opened to the second fuel accumulator reservoir 14b To be done.

The injection start command valve 21 is opened before time d,
After the inlet valve 10 is closed at the time point d, as the internal pressure P ₁ of the pump chamber 9 is increased, the injection start command valve 21, the injection decompression chamber 22, the minute passage 60, and the communication passage 61 are pumped from the pump chamber 9. A slight amount of fuel leaks to the hollow portion 32 of the spool 29 and the pressure accumulating chamber 36 via the, and the internal pressure P ₀ of the pressure accumulating chamber 36 and the hollow portion 32 is slightly increased by this fuel,
The spool 29 is pushed up further than the position at the time point d.
The injection start command valve 21 is closed at a time point f shortly before the spool 29 reaches the top dead center. However, after this, the internal pressure P ₄ of the injection start decompression chamber 22 is changed to the internal pressure of the hollow portion 32 and the pressure accumulation chamber 36. The hollow portion 3 of the spool 29 is passed from the injection decompression chamber 22 through the minute passage 60 and the communication passage 61 until it becomes the same as P _0.
2 and the fuel accumulator 36 flow into the fuel. Due to this inflow, the spool 29 is pushed up to the top dead center.

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

(d) Fuel injection for ignition At a predetermined time j after this, the timing setting valve 19 of the injection start command means 18 is opened and the decompression chamber 20 is communicated with the upstream side of the inlet valve 10. Thereby, the hollow portion 3 of the inlet valve 10
2 and the internal pressure of the pressure accumulating chamber 36 are reduced, the spool 29 starts to descend from the top dead center, and at a time point k when the spool 29 descends to a predetermined position slightly below the top dead center, the injection start command valve 21
Is opened. The control delay time from the opening of the timing setting valve 19 to the opening of the injection start command valve 21 is the decompression chamber 20.
If the initial pressure of (the internal pressure before opening the timing setting valve 19) is constant, it becomes constant. By opening the injection start command valve 21, the internal pressure P ₁ of the pump chamber 9 and the valve closing pressure chamber 12 is rapidly released to the injection start depressurizing chamber 22, and the internal pressure P _{2 of} the first fuel pressure accumulating storage chamber 14a ( At this time point, the internal pressure P ₁ of the valve closing pressure chamber 12 and the valve closing spring 43 are greater than the valve opening force of = P ₃ ).
When the valve closing force consisting of the urging force of
Is opened.

What should be noted here is that by incorporating the injection start command valve 21 and the injection start depressurizing chamber 22 into the plunger 8 of the fuel injection pump 6, the valve closing pressure chamber 12 of the pressure accumulating fuel injector 7 is closed.
An injection start command valve 21 and an injection start depressurization chamber 22 that are sequentially connected to each other are arranged in the vicinity of the valve closing pressure chamber 12 of the pressure accumulating fuel injector 7, and from the valve closing pressure chamber 12 to the injection starting depressurization chamber 22. The distance should be as short as possible. When the distance from the valve closing pressure chamber 12 to the injection start depressurization chamber 22 is shortened in this way, the resistance of the flow path from the injection start command valve 21 to the injection start depressurization chamber 22 decreases and the injection start command valve 21 opens. The pressure reduction gradient of the valve closing pressure chamber 12 after the valve can be made steep. As a result, the control sensitivity can be made sensitive, the range of variation of the valve opening start timing of the injection valve 15 can be reduced, and the control accuracy of the injection start timing can be improved.

Since the pressure release here is the pressure release to the injection start decompression chamber 22 having a relatively small volume, the internal pressure P ₁ of the valve closing pressure chamber 12 is reduced.
Since the amount of fuel to be depressurized is relatively small, the valve opening amount of the injection valve 15 is also kept small, and the fuel injection rate is kept small. When the internal pressure P _{1 of the} pump chamber 9 and the valve closing pressure chamber 12 and the internal pressure P ₄ of the injection start depressurization chamber 22 become equal, the injection start depressurization chamber 22 and the hollow portion 32 are connected by the minute passage 60 and the communication passage 61. Therefore, these internal pressures P
₁ (= P ₄ ) is gradually decompressed. On the other hand, the pressure reduction of the internal pressure P ₂ of the first fuel pressure accumulating and storing chamber 14a due to the fuel injection is more rapid than the pressure reduction of the internal pressure P ₁ of the valve closing pressure chamber 12, and the difference between the valve opening force and the valve closing force is The injection valve 15 from the maximum n time point
The valve opening amount is decreased, and eventually the injection valve 15 is once closed at time n to interrupt the fuel injection. When the injection valve 15 is closed at the time point n, the depressurization of the first fuel pressure accumulating storage chamber 14a stops, while the fuel from the second fuel pressure accumulating storage chamber 14b flows in due to the communication of the pressure setting valve 51. The internal pressure P ₂ of the fuel pressure accumulating storage chamber 14a increases again.

(e) Main fuel injection By the way, the internal pressure P ₀ of the hollow portion 32 of the inlet valve 10 and the pressure accumulation chamber 36 is continuously reduced until the internal pressure of the pressure reduction chamber 20 becomes equal to the internal pressure P ₀ of the pressure accumulation chamber 36 after time j. Then, the spool 29 is lowered almost independently of the fuel injection from the time point l to the time point n. When the spool 29 descends to a predetermined height lower than the top dead center, the inlet valve 1
0 is opened, and the pump chamber 9 and the valve closing pressure chamber 12 are connected to the inlet valve 1
0 and the timing setting valve 19 are connected to the decompression chamber 20. As a result, the internal pressure P ₁ of the pump chamber 9 and the valve closing pressure chamber 12 is sharply and significantly reduced, and the injection valve 15
Is suddenly opened, and a large amount of high-pressure fuel is injected.

The time from the point j when the spool 29 starts to descend to the point k when the injection start command valve 21 is opened and the time from point j to the point o when the inlet valve 10 is opened are from the inlet valve 10 to the decompression chamber 20. It is constant because it is determined by the flow path resistance up to. Further, the time from the time point k to the time point 1 at which the fuel injection is started is constant because it is determined by the flow path resistance from the valve closing pressure chamber 12 to the injection start depressurizing chamber 22. Therefore, the time from the time point l when the ignition injection starts to the time point o when the main injection starts becomes constant regardless of the engine speed, and by setting this time equal to the ignition delay time, Ignites a small amount of fuel injected by to prevent diesel knock and reduce engine operating noise, and when the fuel injected by ignition injection ignites, a large amount of fuel is injected by main injection. It becomes possible to obtain a large output.

In addition, after the inlet valve 10 is opened, the hollow portion 32 of the inlet valve 10 is opened.
And the internal pressure P ₀ of the pressure accumulating chamber 36 is further reduced, and the spool 29 continues to descend even after the time point o. Then, the injection start command valve 21 is closed at time point o or slightly later time point p.
After the time point o, the fuel injection pressure is the first fuel pressure accumulation chamber 14a.
It is the same as the internal pressure P ₂ of P and is gradually reduced. Then, the internal pressure P _{3 of} the second fuel pressure accumulating chamber 14b is the pressure setting valve 51.
The pressure setting valve 51 is closed at the time point q when the pressure is reduced to the set pressure, and the pressure reduction in the first fuel pressure accumulating chamber 14a after the time point q becomes more rapid. The fuel injection rate increases from time o to time q because high-pressure fuel flowing out from the second fuel pressure storage chamber 14b is injected, but after time q, the internal pressure P _{2 of} the first fuel pressure storage chamber 14a increases. The fuel injection rate is reduced. Then, r time after the valve opening force pressure P ₂ is reduced in the first fuel accumulator storage chamber 14a is equal to the closing force by the injection, the internal pressure P ₂ of the first fuel accumulator storage chamber 14a is further continued injection Therefore, the valve closing force becomes stronger than the valve opening force, and the injection valve 15 moves in the valve closing direction. Then, the internal pressure P _{2 of} the first fuel pressure accumulating and storing chamber 14a
At a time point s when the pressure is reduced to a predetermined residual pressure, the injection valve 15 is closed and the fuel injection ends.

In addition, the internal pressure P ₁ of the pump chamber 9 is 0 when the inlet valve 10 is opened.
After the time point, the internal pressure P ₀ of the hollow portion 32 becomes the same as the internal pressure P ₀ in a short time by rapidly and significantly reducing the pressure. Further, the internal pressure P ₄ of the injection start decompression chamber 22 is the same as the internal pressure P ₁ of the pump chamber 9 at the time point k, but when the injection start command valve 21 is opened at the time point k, it rises very rapidly, It becomes the same as the internal pressure P ₁ of the pump chamber 9 within a short time. And while the inlet valve 10 is pressure P ₄ of the internal pressure P ₁ with injection start decompression chamber 22 of the pump chamber 9 when the valve opening at the o point falls sharply, starting injection spool 29 falls below a predetermined height Command valve 2
After the time point p at which the valve 1 is closed, the communication between the injection start depressurization chamber 22 and the pump chamber 9 is cut off, so that the internal pressure P ₄ of the injection start depressurization chamber 22 starts from the minute passage 60 and the communication passage 61. The pressure is gradually released into the hollow portion 32 via the internal pressure of the injection starting decompression chamber 22, and the internal pressure of the injection starting decompression chamber 22 is gradually increased.
Becomes the same as the internal pressures P ₀ and P ₁ . At this time, the pressure accumulation chamber 36
To the maximum injection amount from the pump chamber 9 to the injection start decompression chamber 22.
The amount of fuel corresponding to the amount obtained by subtracting the amount of depressurized fuel from the decompression chamber is added to the amount of the amount of fuel leaked to the pressure accumulating chamber 36 via the spool 29 from the bottom dead center. Is also located in a high position.

(f) Return to initial state The plunger of the fuel injection pump 6 starts from a predetermined time point t after the internal pressures P ₀ , P ₁ and P _{4 of the} injection start decompression chamber 22, the hollow portion 32 and the pump chamber 9 become the same. 8 starts to rise, and as the plunger 8 rises, fuel is sucked from the pressure accumulating chamber 36 into the pump chamber 9.

However, as described above, the amount of fuel stored in the pressure accumulating chamber 36 at time t is the maximum amount of fuel that is the amount of fuel leaking from the pump chamber 9 to the accumulating chamber 36 via the injection start depressurizing chamber 22 and the like. The amount corresponds to the amount obtained by subtracting the amount of fuel depressurized in the decompression chamber 20, and is insufficient to raise the plunger 8 to the top dead center. Therefore, the discharge return valve 56 is opened from time u to time v that is considered to be necessary for the plunger 8 to reach the cam base of the cam, that is, the fuel depressurized into the pressure reducing chamber 20 is stored in the pressure accumulating chamber 20. The plunger 8 is surely returned to the top dead center by being discharged back to 36. In addition, when the plunger 8 is returned to the top dead center at time v in this way, the decompression chamber 2
Between 0 and the pump chamber 9, the fuel corresponding to the amount leaked from the pump chamber 9 to the pressure accumulating chamber 36 through the injection starting pressure reducing chamber 22 and the like is excessively confined. The internal pressure of is higher than the initial pressure at time v. Therefore, by opening the opening / closing valve 59 for initial pressure adjustment from a predetermined time point w after the time point v to the time point x, the hollow portion 32 of the inlet valve 10, the pump chamber 9, and the pressure accumulating chamber 3 are opened.
6, the internal pressures of the valve opening pressure chamber 35, the valve closing pressure chamber 12 and the injection starting pressure reducing chamber 22 are reduced to the initial pressure.

<Embodiment 2> FIG. 5 is a vertical cross-sectional view of a main portion of another embodiment of the present invention.

In this embodiment, the injection start command valve 21 is composed of a double spool valve incorporated in the plunger 8. That is, the child spool 62 is fitted in the lower end portion of the spool 29 so as to be able to move up and down, and the child spool 62 has a through hole 63 whose diameter is reduced at the lower end portion and a peripheral wall of the large diameter portion of the through hole 63 that faces each other. And a valve hole 64 formed so as to be formed. A valve groove 53 of the 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, on the peripheral wall of the lower end portion of the spool 29, when the child spool 62 rises to the top dead center, the valve groove 5
A pair of valve holes 65 and 66 communicating with the valve 3 are formed in the plunger 28. When the spool 29 is located at a height in a predetermined range slightly lower than the top dead center, the valve hole 65 of the spool 29 is formed in the plunger 28.
Injection depressurization passages 52, 54 communicating with the. The other structure is the same as that of the above-described embodiment, and the description thereof is omitted.

In this embodiment, when the timing setting valve 19 of the valve opening start command means 18 is opened to start depressurizing the hollow portion 32, the fuel in the pressure accumulating chamber 36 passes through the through hole 63, and the fuel in the accumulating chamber 36 is reduced.
Although the spool 29 is sucked up and descends, the through hole 63
Since there is a reduced diameter portion, a pressure difference is generated between the pressure accumulating chamber 36 and the hollow portion 32, and the child spool 62 is raised at the same time when the spool 29 is lowered. When the child spool 62 reaches the top dead center, the injection start depressurizing passage 5 of the plunger 8 is reached.
2, 54, 65, 66 of the spool 29 and the child spool 6
The two valve grooves 53 communicate with each other to open the injection start command valve 21, the pump chamber 9 communicates with the injection start depressurizing chamber 22, and the internal pressures of the pump chamber 9 and the valve closing pressure chamber 12 are reduced. become.

The other operations are the same as those in the above-described embodiment, and thus the description thereof will be omitted.

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

Further, since the injection starting decompression chamber 22 has a small volume, the valve closing pressure chamber 12 has a relatively small pressure reduction width and is still maintained at a high pressure. On the other hand, the internal pressure of the fuel pressure accumulating / storing chamber 14 decreases with the fuel injection, the valve opening force of the injection valve 15 due to this internal pressure weakens, and the injection valve 15 is once closed. As a result, the fuel injection for ignition prior to the main injection ends.

The injection valve 15 is closed and the fuel injection is interrupted until a predetermined time elapses after the ignition fuel injection is completed.

When the predetermined time has elapsed, the inlet valve 10 is opened, the internal pressure of the valve closing pressure chamber 12 is released to the pressure reducing chamber 20, the valve closing force due to this internal pressure becomes weak, and the injection valve 15 stores the fuel pressure accumulation. It is pushed again by the valve opening force due to the internal pressure of the chamber 14, and the main fuel injection is started.

In this way, since fuel injection is not performed from once ignition fuel injection is completed until main fuel injection is started, the fuel injection amount during the ignition delay period can be small and the subsequent explosion The rate of pressure increase during the dynamic combustion period is low, and diesel knock is less likely to occur.

[Brief description of drawings]

FIG. 1 is an equivalent circuit diagram of a pressure-accumulation fuel injection device for a diesel engine according to the present invention, FIG. 2 is a vertical sectional view of a unit injector used in the fuel injection device in an initial state, and FIG. FIG. 4 is a longitudinal sectional view of the main part of the unit injector when the command valve is opened, FIG. 4 is a timing diagram for explaining the operation of the unit injector and the injection start command means, and FIG. 5 is another embodiment of the present invention. FIG. 6 is a longitudinal sectional view of the essential part of FIG. 6, and FIG. 6 is an equivalent circuit diagram of the prior invention. 7 ... Accumulation type fuel injector, 10 ... Inlet valve, 11 ... Fuel inlet, 12 ... Valve closing pressure chamber, 13 ... Check valve, 14 ...
Fuel pressure storage chamber, 15 ... Injection valve, 16 ... Injection hole, 1
8 ... Injection start command means, 19 ... Timing setting valve,
20 ... decompression chamber, 21 ... injection start command valve, 22 ... injection decompression chamber, 43 ... valve closing spring.

Claims (1)

[Claims] 1. A pressure-accumulation fuel injector for a diesel engine is provided with a pressure-accumulation fuel injector (7) and a fuel supply system for supplying fuel to the pressure-accumulation fuel injector (7). 11), and a valve closing pressure chamber (12) and a check valve (1
3), a fuel pressure accumulating storage chamber (14), an injection valve (15) and an injection hole (16), and a valve closing spring (43). The injection valve (15) is provided in the fuel pressure accumulating storage chamber (14). While the valve opening is biased by the internal pressure, the valve closing bias is configured by the biasing force of the valve closing spring (43) and the internal pressure of the valve closing pressure chamber (12), and the fuel is supplied from the fuel supply system to the fuel inlet ( 11), valve closing pressure chamber (1
2) and the check valve (13) through the fuel pressure accumulating storage chamber (1
4) and then pressurizing the internal pressure of the valve closing pressure chamber (12) at a predetermined timing to depressurize the injection valve (1).
The valve closing force of 5) is made weaker than the valve opening force, and the injection valve (1
5) In the injection control device of the pressure-accumulation fuel injection device for a diesel engine configured to open the valve, the injection arranged close to the valve-closing pressure chamber (12) of the pressure-accumulation fuel injector (7). An injection start command means (18) for connecting the start command valve (21) and the small volume injection decompression chamber (22) in order and opening the injection start command valve (21) at the predetermined timing is provided. The injection start command valve (21) is opened by the operation of the injection start command means (18) at the above-mentioned predetermined timing to open the internal pressure of the valve closing pressure chamber (12) to a small volume injection start decompression chamber (22). The injection start command means (18) is provided with a pressure reducing valve (19) and a pressure reducing chamber (20).
0) is communicated with the valve closing pressure chamber (12) through the timing setting valve (19) and the inlet valve (10) in order, and the inlet valve (10) is set at a predetermined timing from the valve opening timing of the injection start command valve (21). When the time elapses, the valve is opened and the valve closed pressure chamber (1
An injection control device of a pressure-accumulation fuel injection device for a diesel engine, characterized in that the internal pressure of 2) is released to the decompression chamber (20).