JPH07109184B2 - Fuel supply device for accumulator type fuel injection device of diesel engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply device for a pressure-accumulation fuel injection device for a diesel engine, among which a plunger drive mechanism between a fuel injection cam and a fuel injection pump. In addition, the present invention relates to a type in which the pressure of fuel is used to prevent the occurrence of impact and noise due to intermittent gaps.

<Premise Structure> A fuel supply device for a pressure-accumulation fuel injection device for a diesel engine according to the present invention is, for example, as shown in FIG. 1 to FIG.
It is assumed that it has the following premise structure.

In this premise structure, the pressure of the fuel is used to prevent a gap in the plunger drive mechanism between the fuel injection cam and the plunger of the fuel injection pump. It is designed to eliminate the occurrence.

○ Premise structure That is, as shown in Fig. 3, the fuel is metered by the metering device (4) according to the load of the diesel engine, and the metered fuel is supplied by the pressure feed pump (5) to the fuel supply valve (57). ) And an inlet valve (10) to supply to a fuel injection pump (6), and the fuel injection pump (6) press-fits into a pressure accumulation type fuel injection device (7). A pump chamber (9), a plunger (8) inserted in the pump chamber (9) so as to be able to move forward and backward, and an inlet valve (1) that prevents reverse flow from the pump chamber (9) to the upstream side during discharge.
0) and, as shown in FIG. 1, a valve chamber (28) of the inlet valve (10) is formed in the plunger (8), and a spool (29) built in this valve chamber (28) is formed. ), A valve opening pressure chamber (35) is formed in the upper part of the valve chamber (28), and a stroke adjusting pressure accumulation chamber (36) is formed in the lower part of the valve chamber (28). The hollow portion (32) of the spool (29) is formed in a cylindrical shape with the upper end closed, and is formed in the inlet passage portion (31) formed in the peripheral wall of the spool (29) and the peripheral wall of the plunger (8). Entrance passage part (30)
Via an upstream side passageway (62) formed in the body (23) of the fuel injection pump (6) via the inlet valve (10), and the inlet valve (10) includes an inlet valve hole (33) and an outlet hole (34). Of the inlet valve hole (3
3) is formed in the lower part of the peripheral wall of the spool (29), and its outlet hole (34) is formed in the lower part of the peripheral wall of the plunger (8), and the outlet hole (34) is different from the inlet valve hole (33). The spool (29) communicates when the spool (29) is positioned below a predetermined height slightly lower than the top dead center (U ₂ ), whereas the spool (2
When the spool (29) is located at the top dead center (U ₂ ), the hollow portion (32) and the valve opening pressure chamber (35) are configured to be shut off when the spool 9 is located at a position higher than that. Communication passage (3
7) is formed on the upper part of the peripheral wall of the spool (29), and when the spool (29) is located at the bottom dead center (D ₂ ), the hollow part (32) is formed.
And the valve opening pressure chamber (35) are communicated with each other through the passages (84) (85) (38), the passage (38) of which is formed on the peripheral wall of the plunger (8). The above passage (38) and body (23) in (35)
The pressure accumulating chambers (41) (48) for stabilizing the urging force are connected to each other via the pressure transmission path (46) formed in the spool, and in the combustion supply process (B) shown in FIGS. 4 and 6 (B), the spool ( 29) is located at the bottom dead center (D ₂ ) and the plunger (8) is located at the top dead center (U ₁ ), the fuel supply valve (57) shown in FIG. The fuel metered by the device (4) passes through the pressure pump (5) through the upstream passage (62), the inlet passage portion (30) and the hollow portion (32) shown in FIG. ), The spool (29) is pushed up from the bottom dead center (D ₂ ), and in the fuel injection stroke (C) shown in FIG. 4 and FIG. The injection cam (80) discharges and drives from top dead center (U ₁ ) to bottom dead center (D ₁ ), and as shown in FIG. 6 (C), a part of the fuel (V2 in the pump chamber (9) ) But its ejection In the first half of the drive, it is pressed into the stroke adjusting pressure accumulating chamber (36) through the inlet valve (10), pushes up the spool (29), and closes the inlet valve (10). As shown, the remainder (V ₃ ) of the fuel in the pump chamber (9) is configured to be press-fitted into the pressure accumulating fuel injection device (7) in the latter stage of its discharge drive.

○ Operation of the premise structure Advantage (a) Prevention of impact and noise generation of the plunger drive mechanism Of the overall operation of the pressure accumulation type fuel injection device, the lift down stroke of the fuel injection cam (80) (to the initial state in Fig. 4) At time t-v during the return stroke (F), if there is a gap between the fuel injection cam (80) and the plunger (8), the lift-up stroke of the next fuel injection cam ( Time point c-i during the fuel injection stroke (C) in FIG. 4)
Then, the fuel injection cam (80) collides with the plunger (8),
The impact causes adverse effects such as noise and early wear and deformation.

In the above-described premise structure, in order to eliminate this adverse effect, no gap is formed between the fuel injection cam (80) and the plunger (8), and therefore one cycle of the plunger operation is shown in FIG. It will be described below based on the order of each process shown in A) to (D).

(A) Initial state See FIG. 6 (A) In this initial state, the spool (29) is at the bottom dead center (D ₂ ).
The plunger (8) is located at top dead center (U ₁ ). Inlet valve (10) is open, fuel supply valve (57) is closed, check valve (13)
Is closed by the internal pressure of the fuel pressure accumulating chamber (14).

Maximum discharge amount of the fuel injection pump (6) and (V _0), as the inlet valve (10) closed during the stroke adjustment accumulator maximum capacity (36) and (V _0), but the equal It is set.

(B) the fuel supply stroke FIG. 6 (B) refer to the fuel is supplied is metering amount metering unit (M) (V ₁₎ metering in accordance with the load of the engine.

When the fuel supply valve (57) opens, the metering supply amount (V) ₁ of fuel is pushed into the stroke adjusting pressure accumulating chamber (36) from the metering unit (M), and the spool (29) bottoms. Push it up from the point (D) ₂ to the top dead center (U ₂ ).

(C) Invalid discharge stroke See FIG. 6 (C) After the fuel supply valve (57) is closed, the fuel injection cam (80) enters the lift up stroke (81) and pushes down the plunger (8). Fuel in pump chamber (9) is inlet valve (10)
After that, the ineffective discharge amount (only V ₂ ) is press-fitted into the stroke adjusting pressure accumulating chamber (36). At this time, the check valve (13) is closed by the internal pressure of the fuel pressure accumulation chamber (14).

The fuel in the stroke adjusting pressure accumulating chamber (36) has the maximum volume (V ₁ ) when it is completely injected by the invalid discharge amount (V ₂ ), together with the metering supply amount (V ₁ ) that was in the previous amount. _{Reach 0} ). As a result, the spool (29) rises to the top dead center (U ₂ ), the internal pressure of the stroke adjusting pressure accumulating chamber (36) rises to the valve closing pressure, and the inlet valve (10) is pushed and closed.

The effective discharge amount (V ₃ ) of fuel remaining in the pump chamber (9) is the amount obtained by subtracting the invalid discharge amount (V ₂ ) from the maximum discharge amount (V ₀ ) and is the amount of the stroke adjustment pressure accumulating chamber (36). Maximum volume (V ₀ )
It becomes equal to the metering supply amount (V ₁ ) obtained by subtracting the invalid discharge amount (V ₂ ) from

(D) Effective discharge stroke See Fig. 6 (D). The plunger (8) is pushed further down and the bottom dead center (D ₁ )
The effective discharge amount in the pump chamber (9) (V ₃ <=
The metered supply amount V ₁ >) of the fuel is completely injected into the fuel pressure accumulating storage chamber (14) through the check valve (13).

Then, the effective discharge amount (V ₃ ) of fuel is injected from the pressure accumulating fuel injector (7) into the combustion chamber.

(E) Plunger return stroke See Fig. 6 (A) At the moment when the main timing setting valve (19b) in the metering unit (M) opens for a short time, the internal pressure of the stroke adjusting pressure accumulator (36) becomes Timing setting valve (19b)
The inlet valve (10) is opened by the elastic force of the valve opening pressure chamber (35).

When the fuel injection cam (80) enters the lift down stroke (82), the maximum volume (V ₀ ) of fuel stored in the stroke adjusting pressure accumulator chamber (36) is repressed in the valve opening pressure chamber (35). It is pressed into the pump chamber (9) by force through the inlet valve (10). This causes the spool (29) to move from top dead center (U ₂ ) to bottom dead center (D ₂ ).
The plunger (8) is pressed against the fuel injection cam (80) and is returned from the bottom dead center (D ₁ ) to the top dead center (U ₁ ) to keep contact with the plunger (8). No gap is created between the fuel injection cam (80).

Therefore, the lift-up stroke (81) of the next fuel injection cam (80) (Fig. 6 (C) = fuel injection stroke (C) of Fig. 4).
At the middle time point c-i), the fuel injection cam (80) does not collide with the plunger (8).

This completes one cycle of operation of the plunger (8).

Advantages (b) Reducing the operation delay error of the fuel injection start timing In the state before the fuel injection from the pressure accumulation type fuel injection device (7), the ignition fuel injection process (D) and the main fuel injection shown in FIG. The stroke (E), the effective discharge stroke in FIG. 6 (D), and the one shown in FIG. The plunger (8) is located at the bottom dead center (D ₁ ), the spool (29) is located at the top dead center (U ₂ ), and the inlet valve (10) is closed. As shown in FIG. 1, the passage cross-sectional area at the communicating portion between the upstream passage (62) and the inlet passage portion (30) is wide enough to allow the passage (38) and the pressure transmission passage (46) to communicate with each other. The passage cross-sectional area at the part is wide enough.

From this state, by opening the main timing setting valve (19b) of FIG. 3, the internal pressure of the stroke adjusting pressure accumulating chamber (36) passes through the main timing setting valve (19b) and then the pressure reducing chamber (20).
The pressure in the valve opening chamber (35) is pushed down by the pressure in the valve opening pressure chamber (35), and the inlet valve (10) opens.
Then, the internal pressure of the valve closing pressure chamber (12) in the pressure accumulation type fuel injection device (7) is changed to the inlet valve (10) and the main timing setting valve (19).
After passing through b), the pressure is released to the decompression chamber (20) and the pressure drops. Therefore, the valve closing force, which is the total force of the valve closing spring (43) of the injection valve (15) and the pressure (P ₁ ) of the valve closing pressure chamber (12), is the force of the fuel pressure accumulating chamber (14). It becomes weaker than the valve opening force consisting of, and the injection valve (15) opens, and the accumulator storage chamber (14)
The fuel inside begins to be injected from the injection hole (16).

At this time, the internal pressure of the valve opening pressure chamber (35) decreases while pushing down the spool (29) to open the inlet valve (10). However, as described above, the passage (3
Since the passage cross-sectional area at the communicating portion between the pressure transmitting passageway (46) and the pressure transmitting passageway (46) is wide enough, the internal pressure of the urging force stabilizing pressure accumulating chambers (41) (48) is the valve opening pressure chamber (35). Since it flows smoothly into the valve, the pressure drop rate of the valve opening pressure chamber (35) is reduced,
The valve opening pressure chamber (35) is maintained at high pressure while the inlet valve (10)
Open at high speed.

Moreover, since the passage cross-sectional area at the communicating portion between the upstream passage (62) and the inlet passage portion (30) is sufficiently wide as described above, when the inlet valve (10) is opened. , Since the pressure loss due to the passage resistance in the above communication part is small,
The pressure reduction from the valve closing pressure chamber (12) to the pressure reducing chamber (20) rapidly proceeds.

In this way, the opening speed of the inlet valve (10) also changes with the closing pressure chamber (12).
Since the depressurization speed is also high, the start timing of the main fuel injection has a very small error due to an operation delay and becomes highly accurate.

Advantage (c) As shown in the fuel supply stroke (B) and the fuel supply stroke of FIG. 6 (B) of FIG. 4, which shortens the supply time of the metering fuel (V ₁ ) and contributes to the high speed rotation of the engine. In addition, the metering unit (M) is used to adjust the amount of fuel (V ₁ ) to be stored in the accumulator (3
At the time of press-fitting into 6) (time point ab), since the plunger (8) is held at the top dead center (U ₁ ), the stroke adjusting pressure accumulating chamber (36) and the upstream side shown in FIG. Aisle (62)
The cross-sectional area of the passage is sufficiently wide at the communicating portion between the inlet passage portion (30) and the upstream passage portion (62) for communicating with each other, and the pressure loss due to the passage resistance is small.

As a result, the time required to pump the fuel of the metered fuel amount (V ₁ ) shown in FIG. 6 (B) from the metering unit (M) to the stroke adjusting pressure accumulating chamber (36) is short, and the engine is Can contribute to speeding up.

<Prior Art> In the above-described premise structure, the prior art is configured as follows.

That is, the plunger (8) in the fuel injection stroke (C) is top dead after the opening timing (a) of the fuel supply valve (57) in the fuel supply stroke (B) in FIG. Within the period (z) after the start of fuel supply and before the start of discharge from the point (U ₁ ) to before the start of the discharge drive (y) where
Due to the cam lift shape of the fuel injection cam (80), the plunger (8) is configured to be held at the normal top dead center position (U ₁ ) as shown by the solid line diagram (8a).

<Problems to be Solved by the Invention> ○ Generation and damping of vibration of the spool (29) generated in the premise structure In the above-mentioned premise structure, the spool vibrates and is damped as follows.

One cycle of the operation of the plunger (8) of the fuel injection pump (6) described above is rapidly completed in a short time, and the fuel supply in the fuel supply process (B) is rapidly performed in an instant. Be seen.

As shown in FIG. 6 (B), the fuel of the metered supply amount (V ₁ ) metered in the metering unit (M) is
Accumulation chamber (36) for stroke adjustment with the pressure pump (5) shown.
Is pressed into and pushes the spool (29) from the bottom dead center (D ₂ ) toward the top dead center (U ₂ ) up to the middle of the stroke.

At this time, the pressure in the stroke adjusting pressure accumulating chamber (36) rises sharply and pushes up the spool (29) rapidly.
Due to its motional inertia, the spool (29) exceeds the pressure balance point between the pressure in the stroke adjusting pressure accumulator chamber (36) and the pressure in the valve opening pressure chamber (35), and if there is a large overrun, the reaction Repeatedly pushing back downward at, and vibrating greatly around the pressure balance point.

The initial value of the vibration amplitude of the spool (29) is the dynamic inertial force (driving force) of the spool (29) due to the sudden increase in the pressure in the stroke adjusting pressure accumulator chamber (36) and the opening value accompanying the rise of the spool (29). It is determined by the rate of increase (braking force) of the pressure in the valve pressure chamber (35). The greater the motion inertial force and the smaller the rate of pressure increase, the greater the initial value of the amplitude of the spool (29).

The damping speed of the amplitude of the spool (29) depends on the compression increase rate (braking force) due to the volumetric compression of the valve opening pressure chamber (35) and the stroke adjustment pressure accumulating chamber (36) accompanying the vibration of the spool (29). The smaller the pressure increase rate, the slower the damping speed of the spool (29).

○ Problems of conventional technology The above-mentioned conventional technology has the following problems.

From the fuel supply process (B) to the fuel injection process (C) in FIG.
In the period (z) after the start of fuel supply and before the start of discharge, the plunger (8) is configured to be held at the normal top dead center position (U ₁ ) as shown by the solid line diagram (8a). Therefore, the passage opening at the communication portion between the passage (38) and the pressure transmission passage (46) for connecting the valve opening pressure chamber (35) and the urging force stabilizing pressure accumulating chamber (41) (48) shown in FIG. Since the area is wide enough, the valve opening pressure chamber (35) accompanying the sudden rise of the spool (29)
At the time of compression, the rising pressure in the valve opening pressure chamber (35) quickly escapes to the urging force stabilization pressure accumulating chambers (41) (48). Get smaller.

In addition, the passage cross-sectional area is sufficiently wide to open at the communication portion between the inlet passage portion (30) and the upstream passage portion (62) for communicating the stroke adjusting pressure accumulating chamber (36) and the upstream passage (62). Therefore, the pressure in the stroke adjusting pressure accumulating chamber (36) is increased as much as the pressure during the rising of the stroke adjusting accumulating chamber (36) due to the rapid lowering of the spool (29) quickly escapes to the upstream passage (62). The rate of increase is small.

In this way, since the pressure increase rate (braking force) of both the valve opening pressure chamber (35) and the stroke adjusting pressure accumulating chamber (36) becomes small,
The damping speed of the vibration of the spool (29) becomes slow, and the spool (29) continues to vibrate greatly for a long time. Then, the plunger (8) is driven downward, and the sixth
In the invalid discharge stroke of Fig. (C), even when the normal amount of invalid fuel (V ₂ ) of fuel is completely pressed from the pump chamber (9) into the stroke adjusting pressure accumulating chamber (36), the spool ( 29) still continues to vibrate. Therefore, while the spool (29) excessively moves downward during vibration, the invalid discharge amount (V ₂ ) becomes larger than the regular amount due to the extra opening of the inlet valve (10). The remaining effective discharge amount (V ₃ ) becomes small, the fuel injection amount becomes insufficient with respect to the load of the engine, the torque of the engine becomes insufficient, and the rotation speed decreases.

The subject of the present invention is to inject the fuel by the vibration of the spool (29) accompanying the supply of the fuel of the controlled fuel amount (V ₁ ) shown in FIG. 6 (B) to the stroke adjusting pressure accumulating chamber (36). Control the lack of quantity,
This is to prevent a reduction in rotation due to insufficient torque of the engine.

<Means for Solving the Problems> The present invention is characterized in that the following characteristic structure is added to the above-mentioned premise structure in order to achieve the above-mentioned problems, for example, as shown in FIG. 1 and FIG. And

That is, as shown in FIG. 4, the plunger (8) in the fuel injection stroke (C) is started after the valve opening start timing (a) of the fuel supply valve (57) in the fuel supply stroke (B). )
Is started from the top dead center (U ₁ ) and before the discharge drive start timing (y) that starts to fall, after the fuel supply is started and before the discharge is started (z), depending on the cam lift shape of the fuel injection cam (80). , The plunger (8) is configured to be excessively moved to the upper dead center upper position (UO) above the normal upper dead center position (U ₁ ) as shown by the broken line diagram (8b). In the state where the plunger (8) excessively moves to the upper dead center upper position (UO), on the one hand, the valve opening pressure chamber (35) and the urging force stabilization pressure accumulating chambers (41) (48) shown in FIG. Plunger (8) for communicating
Of the passage (38) and the pressure transmission passage (46) of the body (23) of the fuel injection pump (6), the lower edge (38) of the passage (38).
a) is biased to the upper side of the lower edge (46a) of the pressure transmission path (46) to reduce the passage cross-sectional area in the communication portion between the passage (38) and the pressure transmission path (46), and on the other hand, The lower edge (30a) of the inlet passage portion (30) formed in the plunger (8) is lower than the lower edge (62a) of the upstream passage (62) formed in the body (23) of the fuel injection pump (6). It is characterized in that it is biased to the upper side so as to reduce the passage cross-sectional area at the communicating portion between the upstream passage (62) and the inlet passage portion (30).

The passage cross-sectional area at the connection between the upstream passage (62) and the inlet passage portion (30) and the passage cross-sectional area at the connection between the passage (38) and the pressure transmission passage (46) are “decreased”. To "enable" includes blocking these passage cross-sectional areas.

<Operation and Effect of the Invention> The present invention has the following operation and effect (d) since the above-described characteristic structure is added to the above-described premise structure.

(D) Preventing the shortage of fuel injection amount due to vibration of the spool (29) From the fuel supply stroke (B) to the fuel injection stroke (C) in FIG.
Within the period (z) after the start of fuel supply and before the start of discharge over the previous period, the plunger (8) is located above the normal top dead center position (U ₁ ) and above the top dead center as shown by the broken line diagram (8b). It is configured to be excessively moved to the position (UO), and the passage (38) and the pressure transmission path (46) for connecting the valve opening pressure chamber (35) and the biasing force stabilization pressure accumulating chambers (41) (48). ) Is configured so as to reduce the passage cross-sectional area at the communicating portion, the compression of the valve opening pressure chamber (35) due to the sudden rise of the spool (29)
The rate of increase in pressure in the valve opening pressure chamber (35) increases as much as the rising pressure in the valve opening pressure chamber (35) becomes less likely to escape to the biasing force stabilization pressure accumulation chambers (41) (48).

In addition, the cross-sectional area of the passage is reduced even in the communication portion between the inlet passage portion (30) and the upstream passage portion (62) for communicating the stroke adjusting pressure accumulating chamber (36) and the upstream passage (62). Since it is configured, the stroke adjusting pressure accumulating chamber (36) is reduced by the amount that the pressure during the rising of the stroke adjusting accumulating chamber (36) accompanying the lowering of the spool (29) is less likely to escape to the upstream side passageway (62). The pressure rise rate of the

In this way, since the pressure increase rate (braking force) of both the valve opening pressure chamber (35) and the stroke adjusting pressure accumulating chamber (36) becomes large,
Vibration of the spool (29) is less likely to occur, and even if the spool (29) begins to vibrate, the vibration is damped in a short time.

As a result, the plunger (8) is driven downward, and in the invalid discharge stroke of FIG. 6 (C), the normal amount of invalid discharge (V ₂ )
At the time when the fuel has been press-fitted from the pump chamber (9) into the stroke adjusting pressure accumulating chamber (36), the vibration of the spool (29) is sufficiently prevented. Therefore, the "spool (2
The inlet valve (1
0) is opened by an extra amount, the invalid discharge amount (V ₂ ) becomes larger than the regular amount, and the remaining effective discharge amount (V ₃ ) becomes smaller. ” On the other hand, the fuel injection amount does not become insufficient, and it is possible to prevent the engine from decreasing in rotation due to insufficient torque.

<Embodiment> An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 is a vertical cross-sectional view of an inlet valve of a fuel injection pump for a pressure accumulation type fuel injection device according to the present invention when fuel is supplied from a pressure feed pump to a fuel injection pump, and FIG. 2 is the pressure accumulation type fuel in an initial state. FIG. 3 is a vertical cross-sectional view of a unit injector of the injection device, FIG. 3 is an equivalent circuit diagram of the pressure-accumulation fuel injection device, and FIG. 4 is a timing diagram showing operation timing of main parts of the pressure-accumulation fuel injection device. is there.

As shown in FIG. 3, the pressure-accumulation fuel injection device 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 27,
A fuel injection pump 6 and an accumulator 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 that supplies fuel to the pressure-accumulation fuel injector 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 increase or decrease 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 FIGS. 1 and 2, the fuel injection pump 6 described above.
Is separated from the upper surface (right surface in FIG. 2) of the body 23 of the unit injector U into a plunger insertion hole 24 which is recessed, and is divided by the plunger 8 below the plunger insertion hole 24. Pump room 9 and
An inlet valve 10 is provided.

The inlet valve 10 can be provided independently of the plunger 8, but in this case, it is incorporated in the plunger 8 in order to reduce the size of the unit injector U. That is, a substantially cylindrical valve chamber 28 whose upper end and lower end are slightly expanded is formed inside the plunger 8, and a spool 29 is slidably fitted in the valve chamber 28. . This spool 29
Is a hollow cylinder with a closed top,
32 is an upstream side formed in the body 23 through an inlet passage portion 31 that penetrates a portion of the peripheral wall of the spool 29 at an intermediate height and an inlet passage portion 30 that penetrates a portion of the plunger 8 at an intermediate height of the peripheral wall. It is always connected to the passage 62. Above inlet valve 10
Is an inlet valve hole 33 formed in the lower half of the peripheral wall of the spool 29.
And an outlet hole (hereinafter referred to as “outlet”) 34 formed in the lower half of the peripheral wall of the plunger 8, and when the spool 29 is positioned lower than a predetermined height slightly lower than the top dead center, the inlet valve hole 33 Is communicated with the outlet 34 to open the valve, and when the spool 29 is positioned higher than that, the inlet valve hole 33 is blocked from the outlet 34 and closed.

Inside the valve chamber 28, there is a valve-opening pressure chamber 35 in the upper part and a pressure-accumulating chamber 36 for adjusting the plunger stroke in the lower part.
It is divided by each. And spool 29
Is urged in the valve closing direction by the internal pressure P _{0 of} the hollow portion 32 communicating with the upstream side of the inlet valve 10 and the pressure accumulating chamber 36, and the internal pressure of the valve opening pressure chamber 35.
It is biased in the valve opening direction by P ₀ ′. The valve opening pressure chamber 35 has a hollow portion formed by a communication hole 37 formed in an upper portion of the peripheral wall of the spool 29 when the spool 29 is located at the top dead center.
When the spool 29 is located at the bottom dead center, the spool 29 is communicated with the hollow portion 32 through the communication hole 37 and the passage 38 formed in the upper portion of the peripheral wall of the plunger 8. Made of

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 accumulator fuel injector 7 is fitted and supported in the injection pipe insertion hole 25. .

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

The valve stem 42 of the injection valve 15 penetrates through the first fuel pressure accumulating and storing chamber 14a, the check valve chamber 39 and the valve closing pressure chamber 12, and the upper end thereof is closed in the upper half of the injection pipe 26. It is inserted into the valve spring chamber 41.

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. The valve closing spring 1 is directed toward the valve seat 13b formed by the enlarged diameter portion formed at the intermediate height of the valve mold 42 of the injection valve 15.
Uplifted by 3c. Therefore, this check valve 13
13a is the internal pressure of the valve closing pressure chamber 12 (= the internal pressure of the pump chamber 9).
The internal pressure P _{2 of} the first fuel pressure accumulating injection chamber 14a is activated by the valve opening at P ₁ ).
Is closed 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 first fuel pressure accumulation injection chamber 14
It will be opened only when the internal pressure P ₂ of a exceeds.

An injection valve is provided inside the valve closing spring chamber 41 through the valve stem 42.
A valve closing spring 43 for urging 15 in the valve closing direction is inserted.

Therefore, the injection valve 15 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 and storing chamber 14a. After the supply of fuel 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 opening spring chamber 41 is closed by a spring seat 44 that sets the biasing 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, and the valve closing spring chamber 41 is closed. The lower end portion communicates with the valve opening pressure chamber 35 of the inlet valve 10 via the pressure transmission passage 46 and the passage 38 formed in the plunger 8. Also, the injection pipe 26
A cap 47 that covers the spring seat 44 and the valve opening restrictor 45 is screwed onto the upper end of the space 48 formed between the cap 47 and the spring seat 44 and the valve opening restrictor 45. Are communicated with the valve closing spring chamber 41 via a communication passage 49 that is provided in the valve opening restrictor 45. By configuring in this way, the cap
A space 48 formed between the valve seat 47 and the spring seat 44 and the valve opening restrictor 45 absorbs a sudden pressure change in the valve opening pressure chamber 35 of the inlet valve 10 together with the valve closing spring chamber 41 for stabilizing the valve opening pressure. It will play the role of accumulator.

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 body 23 portion around it.
The second fuel pressure accumulating storage chamber 14b is provided with a check valve 50 and a pressure setting valve 5
It is connected via 1 to the first fuel pressure accumulator and injection chamber 14a.

This check valve 50 has the _second internal pressure P ₂ of the first fuel pressure accumulating injection chamber 14a
When the pressure becomes higher than the residual pressure of the fuel pressure accumulating chamber 14b (for example, about 700 atm), the valve is opened to move from the first fuel pressure accumulating injection chamber 14a
It is configured to allow the fuel to flow into the fuel pressure accumulating storage chamber 14b and prevent the backflow from the second fuel pressure accumulating storage chamber 14b to the first fuel pressure accumulating injection chamber 14a. In addition, the pressure setting valve
The valve 51 opens when the internal pressure P ₃ of the second fuel pressure accumulating chamber 14b rises to a pressure other than a predetermined residual pressure, and the fuel flows between the second fuel pressure accumulating chamber 14b and the first fuel pressure accumulating injection chamber 14a. acceptable, so that the internal pressure P ₃ of the second fuel accumulator reservoir 14b is 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 Made of

As shown in FIG. 3, the injection control device includes an ignition injection start command valve 21 incorporated in the unit injector U.
Further, it is provided with an ignition fuel injection decompression chamber 22 and an injection start command means 18 incorporated in the metering unit M.

The ignition 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. 1 and 2. That is, the injection start command valve 21 for ignition includes an injection start depressurizing passage 52 for communicating the pump chamber 9 and the valve chamber 28 below the outlet 34 of the inlet valve on the peripheral wall of the plunger 8, and the inlet valve hole. Spool below 33
It is composed of a valve groove 53 that is recessed all around the peripheral surface of 29, is lower than the top dead center of the spool 29, and is within a predetermined range including the position of the spool 29 at which the inlet valve 10 is opened and closed. When the spool 29 is located at the height, the injection start depressurizing passage 52 and the valve groove 53 are communicated with each other to open the valve.

The ignition fuel injection decompression chamber 22 includes an injection start 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 It communicates with the valve chamber 28 via a pressure reducing passage 54 formed through the peripheral wall portion. The ignition fuel injection decompression chamber 22 includes an injection start decompression passage 52 and a valve groove.
When communicating with 53, the pump chamber 9 is communicated with via the pressure reducing passage 54, the valve groove 53 and the injection starting pressure reducing passage 52. Further, the ignition fuel injection decompression chamber 22 is always communicated with the hollow portion 32 of the spool 29 through the minute passage 60 formed in the peripheral wall of the plunger 8 and the communication passage 61 formed in the peripheral wall of the spool 29. Made of

As shown in FIG. 3, the injection start command means 18 controls the inlet valve 10
Timing setting valve 19 and decompression chamber connected in sequence upstream of the
20 is provided, and the decompression chamber 20 is communicated with the upstream side of the inlet valve 10 when the timing setting valve 19 is opened at a predetermined crankshaft angle in conjunction with a crankshaft (not shown). . The timing setting valve 19 includes an advance control valve 19a for advancing or delaying the injection start timing according to the engine speed, and an advance control valve 1a within the advance range.
It is composed of a main timing setting valve 19b connecting the inlet valve 10 and the valve 9a. As shown in FIG. 3, the advance control valve 19a is composed of a hydraulically actuated spool valve, and the spool valve body 72 is pushed up and retarded by a balance spring 73 in the valve box 71. On the other hand, the fuel pressure in the hydraulic pressure operating chamber 74 is pushed down and pressurized toward the advance side, and is configured to be adjustable up and down to a position where the pushing down pressure and the pushing up elastic force are balanced. There is.

On the inlet side of the valve box 71, from the top, the retard side valve inlet 75
・ Intermediate timing valve inlet 76 ・ and advance side valve inlet 77 open,
A valve outlet 78 opens on the outlet side of the valve box 71. Spool disc
A spool valve body passage 79 is formed in 72 in a transverse shape. The spool valve body passage 79 has the retard side valve inlet 75 on the inlet side.
The intermediate timing valve inlet 76 and the advance side valve inlet 77 are selectively opened, while the outlet side is always communicated with the decompression chamber 20 via the valve outlet 78.

The hydraulic pressure working chamber 74 communicates with the outlet side of the pressure regulator 3 via a pressure communication passage 90. As the engine speed increases from low speed to medium speed to high speed, the pressure regulator 3
The fuel pressure on the outlet side of the valve goes from low pressure to high pressure through medium pressure, and the spool valve element 72 is at the operating pressure of the hydraulic pressure operating chamber 74, and from the upper retard position to the intermediate height position to the lower advance angle. The spool valve passage 79 is moved to the side position and communicates with the retard side valve inlet 75 through the intermediate timing valve inlet 76 to the advance side valve inlet 77.

The main timing setting valve 19b is composed of a rotary valve and has a valve box 8
The rotary valve body 89 is configured to rotate in the clockwise direction in conjunction with the crankshaft of the engine within 8.

A valve inlet 83 is opened at the inlet side of the valve box 88, and an advance side valve outlet 84 and an intermediate timing valve outlet 85 are sequentially provided at the outlet side from the upper side to the lower side in the rotating direction of the rotary valve body 89.・ And the retard side valve outlet 86 opens.

When the rotation angle of the crankshaft of the engine reaches the fuel injection start timing, the rotary valve body passage 87 of the rotary valve body 89 continues to communicate with the valve inlet 83 for a while at its inlet side, whereas it does not reach its outlet side. The advance side valve outlet 84, the intermediate timing valve outlet 85, and the retard side valve outlet 86 are sequentially communicated with each other.

The injection start command means 18 configured as described above is for closing the valve closing pressure chamber 12 by opening the rotary valve body 89 when the rotation angle of the engine crankshaft reaches the fuel injection start timing. By releasing the pressure P ₁ to the decompression chamber 20 via the inlet valve 10, the main timing setting valve 19b, and the advance control valve 19a,
The valve closing pressure P ₁ of the injection valve 15 of the pressure accumulation type fuel injector 7 is weakened, and the injection valve 15 is opened at the valve opening pressure P 2 due to the fuel accumulation pressure in the fuel pressure accumulation chamber 14 The fuel accumulated in the storage chamber 14 starts to be injected from the injection port 16 into the combustion chamber.

In this way, by opening the rotary valve body 89, the injection valve
When opening 15 to start fuel injection,
First of all, when the engine is rotating at high speed, the fuel pressure at the outlet of the pressure regulator 3 becomes high, so that the pressure in the hydraulic pressure working chamber 74 becomes high and the spool valve body 72 is moved to the advanced position. It is pushed down to open the spool valve disc passage 79 to the advance side valve disc inlet 77.

Therefore, when the rotation angle of the rotary valve body 89 reaches an early timing in the variable region of the fuel injection start timing, that is, the advance timing, and the rotary valve body passage 87 is opened to the advance side valve outlet 84. Then, the valve closing pressure P ₁ of the valve closing pressure chamber 12 escapes to the pressure reducing chamber 20 via the rotary valve body passage 87, the advance side valve outlet 84, the advance side valve inlet 77, and the spool valve body passage 79. The pressure is reduced and the pressure is reduced. As a result, the fuel injection timing is advanced to the advance timing.

Secondly, on the contrary, when the engine is rotating at a low speed, the fuel pressure at the outlet of the pressure regulator 3 becomes low, so that the pressure in the hydraulic pressure operating chamber 74 becomes low and the spool valve element 72
Is pushed up to the retard position by the balance spring 73, and the spool valve body passage 79 communicates with the retard side valve inlet 75.

Therefore, the rotary valve body passage 87 cannot communicate with the spool valve body passage 79 when it first communicates with the advance side valve outlet 84, and cannot communicate with the spool valve body passage 79 when it reaches the intermediate timing valve outlet 85 next. And, the communication is established only when the retard side valve outlet 86 is reached. As a result, the fuel injection timing is delayed to the retarded timing.

And third, when the engine is rotating at medium speed,
By operating in the same manner as in the case of the low speed rotation, the fuel injection timing is adjusted and controlled to the intermediate timing. Further, the injection start command means 18 is provided with a discharge return passage 55 that connects the decompression chamber 20 and the inlet valve 10 in parallel with the timing setting valve 19, and the timing setting that is once opened in the discharge return passage 55 is set. A discharge return valve 56 that is opened at a predetermined timing after the valve 19 is shut off and fuel injection is completed 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. An initial pressure adjusting pressure transmission path 58 that connects the outlet of the pressure adjusting device 3 to the upstream side of the edge filter 27 is connected in parallel with the pressure adjusting device 4, the pressure feed pump 5, and the fuel supply valve 57. 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 57, the timing setting valve 19, and the discharge return valve 56 described above.
Although the on-off valve 59 and the on-off valve 59 may be provided separately, each of these valves is opened and closed by a predetermined crankshaft, and therefore, as one combined timing control valve having a common rotary valve body linked to the crankshaft. It is possible to configure.

In summary, the features of the present invention are as follows.

That is, as shown in FIG. 4, the plunger (8) in the fuel injection stroke (C) is started after the valve opening start timing (a) of the fuel supply valve (57) in the fuel supply stroke (B). )
Is started from the top dead center (U ₁ ) and before the discharge drive start timing (y) that starts to fall, after the fuel supply is started and before the discharge is started (z), depending on the cam lift shape of the fuel injection cam (80). , The plunger (8) is configured to be excessively moved to the upper dead center upper position (UO) above the normal upper dead center position (U ₁ ) as shown by the broken line diagram (8b). In the state where the plunger (8) excessively moves to the upper dead center upper position (UO), on the one hand, the valve opening pressure chamber (35) and the urging force stabilization pressure accumulating chambers (41) (48) shown in FIG. Plunger (8) for communicating
Of the passage (38) and the pressure transmission passage (46) of the body (23) of the fuel injection pump (6), the lower edge (38) of the passage (38).
a) is biased to the upper side of the lower edge (46a) of the pressure transmission path (46) to reduce the passage cross-sectional area in the communication portion between the passage (38) and the pressure transmission path (46), and on the other hand, The lower edge (30a) of the inlet passage portion (30) formed in the plunger (8) is lower than the lower edge (62a) of the upstream passage (62) formed in the body (23) of the fuel injection pump (6). It is characterized in that it is biased to the upper side so as to reduce the passage cross-sectional area at the communicating portion between the upstream passage (62) and the inlet passage portion (30).

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, the timing setting valve 19, the discharge return valve 56, and the opening / closing valve 59 are all closed, and as shown in FIG. 2, the plunger 8 of the fuel injection pump 6 is closed. 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 ignition injection start command valve 21 is closed. The check valve 13 is closed by the valve closing spring 13c, and the injection valve 15 is closed by the valve closing spring 43. Further, the check valve 50 and the pressure setting valve 51 of the fuel pressure accumulating chamber 14 are both closed.

Further, in the initial state, the space inside the valve opening pressure chamber 35, the valve closing spring chamber 41 and the cap 47, which communicates with the hollow portion 32 of the inlet valve 10.
48 of the internal pressure P ₀ ', the internal pressure P ₀ of the accumulator 36, the internal pressure P ₄ of the ignition fuel injection 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 is equal predetermined Has become the initial pressure.
The internal pressure P ₂ of the first fuel pressure storage chamber 14a on the downstream side of the check valve 13 is equal to the residual pressure after the injection is completed (the internal pressure when the injection valve 15 is closed), and the internal pressure P of the second fuel pressure storage chamber 14b is ₃ is the closing pressure of the pressure setting valve 51 (for example, 700 atm).

(B) Fuel supply process (fuel supply to the injection pump 6) The supply of fuel to the fuel injection pump 6 is started in 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 pump 5 to the fuel injection pump 6 are switched.
The fuel whose pressure has been regulated and which has been regulated is pumped. This fuel is first pressed into the pressure accumulating chamber 36 via the inlet passage portions 30 and 31 and the hollow portion 32, and moves the spool 29 to the top dead center side.

At engine startup, under full load or overload, the maximum injection amount of fuel is pumped from the pump 5 and the spool 29 is moved to top dead center.
Is moved to an intermediate position between the bottom dead center and the top dead center, and the fuel supply valve 57 is closed at time b when the injection of fuel into the fuel injection pump 6 is completed.

At this time point b, the internal pressure P ₁ of the pump chamber 9 and the internal pressure of the pressure accumulating chamber 36
Although P ₀ and pressure P ₀ of the valve-opening pressure chamber 35 that is against the internal pressure P ₀ of the accumulator 36 'is increased from the initial pressure, than the internal pressure P ₂ of the first fuel injection accumulator 14a low pressure Therefore, the check valve 13 cannot be opened.

It should be noted that when the fuel is supplied to the injection pump 6, the plunger 8 supplies the pressure-accumulation fuel injector 7 from a predetermined timing after the fuel supply valve 57 is opened, as shown by a broken line in FIG. That is, it is to be raised above the normal top dead center for a predetermined timing until the ejection starts. As a result, as shown in FIG. 1, the connection flow passage cross-sectional area between the upstream side passage 62 and the inlet side passage portion 30 and the connection flow passage cross-sectional area between the passage 38 and the pressure transmission passage 46 are reduced, and the valve opening pressure is reduced. Chamber 35
Then, the spring constant of the internal pressure between the hollow portion 32 and the pressure accumulating chamber becomes large, and the motion inertia of the spool 29 is braked. Therefore, even if the spool 29, which is vigorously moved by the fuel supply pressure at the start of fuel supply from the pressure pump 5, vibrates around the pressure balance point, the valve opening pressure chamber 35 and
The vibration is eliminated by the braking action due to the increase of the spring constant of the internal pressure between the hollow portion 32 and the pressure accumulating chamber.

(C) Fuel injection stroke (injection of fuel into the pressure-accumulation fuel injector 7) The plunger 8 is moved from the top dead center by a cam (not shown) from the time point c to the time point i after the time point b at which the fuel supply to the injection pump 6 ends. Pushed down. Internal pressure of pump room 9
The internal pressure P ₀ of P ₁ and the pressure accumulating chamber 36 is further increased from the time point c, and the spool 29 is further raised to move from the pump chamber 9 to the pressure accumulating chamber.
Fuel is pressed into 36, and at time d, the spool 29 rises to a predetermined height near the top dead center and the inlet valve 10 is closed. As described above, the vibration of the spool 29 generated when the fuel is supplied to the injection pump 6 has been resolved by the time point d, so the inlet valve 10 is always at an ideal timing that does not take such vibration into consideration. It will be 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-accumulation 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 can be used between the time point c and the time point d. Therefore, the amount of fuel injected into the pressure accumulating chamber 36 corresponds to the difference between the maximum injection amount and the fuel supply amount injected 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 the movement of the plunger 8 from the top dead center to the bottom dead center is also equal to the maximum injection amount, after the time d, the plunger 8 reaches the bottom dead center until the time i. The amount of fuel injected into the accumulator fuel injector 7 from the pump chamber 9 is the maximum injection amount and c
It corresponds to the difference from the amount of fuel press-fitted from the pump chamber 9 into the pressure accumulating chamber 36 between time point e and time point e, that is, the fuel supply amount from the pressure feed pump 5.

In addition, the internal pressure of the ignition fuel injection decompression chamber 22 from the time point a to the time point d is set to the ignition fuel injection decompression chamber 22 before the time point d via the minute passage 60, the communication passage 61 hollow portion 32 and the inlet valve 10. Since it communicates with the pump chamber 9, the pressure accumulating chamber changes relatively slowly.
36 and the internal pressures P ₀ and P ₁ of the pump chamber 9 change similarly.

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 accumulation chamber 14a. Further, at the time h when the fuel pressure P ₁ (here, P ₂ ) from the pump chamber 9 to the first fuel pressure accumulating storage chamber 14a exceeds the set pressure of the pressure setting valve 51, the check valve 50 is opened and the check valve 50 is opened. Fuel is press-fitted from the first fuel pressure storage chamber 14a into the second fuel pressure storage chamber 14b.

Incidentally, the ignition injection start command valve 21 is opened before the d point, the inlet valve 10 from being closed at the d point, the pump chamber 9 As the internal pressure P ₁ of the pump chamber 9 is increased Through the ignition injection start command valve 21, the ignition fuel injection decompression chamber 22, the minute passage 60 and the communication passage 61, the hollow portion 32 of the spool 29 and the accumulator chamber 36.
A very small amount of fuel leaks, and this fuel causes the accumulator
The internal pressure P ₀ of 36 and the hollow 32 is slightly increased, and the spool 29
Is further pushed up from the position at time d. Ignition injection start command valve at time f shortly before spool 29 reaches top dead center
21 is closed, but after this, the decompression chamber for ignition fuel injection 22
Until the internal pressure P ₄ of the same becomes equal to the internal pressure P _{0 of the} hollow portion 32 and the pressure accumulating chamber 36, from the ignition fuel injection pressure reducing chamber 22 to the minute passage 60 and the communicating passage.
The fuel flows into the hollow portion 32 of the spool 29 and the pressure accumulating chamber 36 via 61. 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 terminated at the point i when the plunger 8 reaches the bottom dead center, and each check valve
13,50 are closed.

(D) Ignition fuel injection stroke 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 connected to the upstream side of the inlet valve 10. Thereby, the hollow portion 32 of the inlet valve 10 and the accumulator chamber
The internal pressure of 36 is reduced, the spool 29 starts to descend from the top dead center, and the ignition injection start command valve 21 is opened at time k when the spool 29 descends to a predetermined position slightly below the top dead center.
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 constant if the initial pressure of the decompression chamber 20 (the internal pressure before opening the timing setting valve 19) is constant. Be constant. By opening the ignition 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 ignition fuel injection decompression chamber 22, and the first fuel pressure accumulating chamber 14
At the time point l, when the internal pressure P ₁ of the valve closing pressure chamber 12 and the valve closing force of the biasing force of the valve closing spring 43 become weaker than the valve opening force of the internal pressure P ₂ (= P ₃ at this point). 15 is opened.

What should be noted here is that the ignition injection start command valve 21 and the ignition fuel injection decompression chamber 22 are incorporated into the plunger 8 of the fuel injection pump 6 so that the valve closing pressure chamber 12 of the pressure accumulating fuel injector 7 is provided. An ignition injection start command valve 21 and an ignition fuel injection decompression chamber 22 which are sequentially connected are arranged near the valve closing pressure chamber 12 of the accumulator fuel injector 7, and the ignition fuel injection decompression chamber 12 is opened from the valve closing pressure chamber 12 to the ignition fuel injection decompression chamber.
The distance to 22 should be as short as possible. In this way, from the valve closing pressure chamber 12 to the ignition fuel injection decompression chamber 22.
If the distance is shortened, the resistance of the flow path from the ignition injection start command valve 21 to the ignition fuel injection decompression chamber 22 becomes small, and the pressure reduction of the valve closing pressure chamber 12 after the ignition injection start command valve 21 is opened. The slope can be steep. As a result, the control sensitivity can be made sensitive, the range of variation in 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 depressurization here is the depressurization to the ignition fuel injection depressurization chamber 22 having a relatively small volume, the amount of the depressurized fuel of the internal pressure P ₁ of the valve closing pressure chamber 12 is comparatively small. Injection valve 15
The valve opening amount of 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 becomes equal to the internal pressure P ₄ of the ignition fuel injection decompression chamber 22, the ignition fuel injection decompression chamber 22 and the hollow portion 32 are caused by the minute passage 60 and the communication passage 61. Since they are communicated with each other, these internal pressures P ₁ (= P ₄ ) are gradually reduced. 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 valve opening amount of the injection valve 15 decreases from the maximum point m, and then the injection valve 15 is closed once and the fuel injection is interrupted at the point n. When the injection valve 15 is closed at time n, the first fuel pressure accumulation chamber 14a
While the depressurization is stopped, the fuel from the second fuel pressure accumulating and storing chamber 14b flows in due to the communication of the pressure setting valve 51, so that the internal pressure P ₂ of the first fuel pressure accumulating and storing chamber 14a increases again.

(E) Main fuel injection stroke By the way, the internal pressure P ₀ of the hollow portion 32 of the inlet valve 10 and the pressure accumulating chamber 36 is continuously reduced until time j becomes equal to the internal pressure P ₀ of the pressure accumulating chamber 20. 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 10 is opened, and the pump chamber 9 and the valve closing pressure chamber 12 are decompressed via the inlet valve 10 and the timing setting valve 19. Connected to chamber 20. As a result, the pump chamber 9
Also, the internal pressure P ₁ of the valve closing pressure chamber 12 is sharply and significantly reduced, the injection valve 15 is suddenly and largely opened, and a large amount of high-pressure fuel is injected all at once.

The time from the time point j when the spool 29 starts descending to the time point k when the ignition injection start command valve 21 is opened and the time from time point j to the time o when the inlet valve 10 is opened are reduced from the inlet valve 10. It is constant because it is determined by the flow path resistance to the chamber 20. 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 passage resistance from the valve closing pressure chamber 12 to the ignition fuel injection decompression 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, Ignite a small amount of injected fuel to prevent the generation of diesel knocks and reduce engine operating noise.In addition, when the fuel injected by the ignition injection is ignited, a large amount of fuel is injected by the main injection. It becomes possible to obtain a large output, and it is possible to successfully achieve both prevention of diesel knock and securing of a high output.

After the inlet valve 10 is opened, the internal pressure P ₀ of the hollow portion 32 of the inlet valve 10 and the pressure accumulating chamber 36 is further reduced, and the spool 29 is o
It continues to decline after that time. Then, the ignition injection start command valve 21 is closed at a time point p slightly after the time point o. After the time point o, the fuel injection pressure is the internal pressure P ₂ of the first fuel pressure accumulating chamber 14a.
It is the same as, and the pressure is gradually reduced. Then, the pressure setting valve 51 is closed at the time point q when the internal pressure P _{3 of} the second fuel pressure accumulating chamber 14b is reduced to the setting pressure of the pressure setting valve 51, and the depressurization of the first fuel pressure accumulating chamber 14a after this q time point is reduced. It gets even sharper. From the time point o to the time point q when the fuel injection rate is the second fuel pressure accumulation chamber
Although the high-pressure fuel flowing out of 14b is injected, it rises, but after the time point q, the internal pressure P ₂ of the first fuel pressure accumulating / storing chamber 14a decreases sharply, and the fuel injection rate decreases. 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, at the time s when the internal pressure P _{2 of} the first fuel pressure accumulating and storing chamber 14a is reduced to a predetermined residual pressure, the injection valve 15 is closed and the fuel injection ends.

The internal pressure P ₁ of the pump chamber 9 is rapidly and significantly reduced after the time point o when the inlet valve 10 is opened, and becomes the same as the internal pressure P ₀ of the hollow portion 32 within a short time. Also, a decompression chamber for ignition fuel injection
The internal pressure P ₄ of 22 is the same as the internal pressure P ₀ of the hollow portion 32 at the time point k, but when the ignition injection start command valve 21 is opened at the time point k, it rises very rapidly and within a short time. It becomes the same as the internal pressure P ₁ of the pump chamber 9. When the inlet valve 10 is opened at time o, the internal pressure P _{1 of the} pump chamber 9 and the decompression chamber for ignition fuel injection are increased.
The internal pressure P ₄ of 22 suddenly drops, but after the time point p when the spool 29 becomes below a predetermined height and the ignition injection start command valve 21 is closed, the decompression chamber 22 for ignition fuel injection and the pump chamber Since the communication with 9 is interrupted, the internal pressure P ₄ of the ignition fuel injection decompression chamber 22 is from now on through the minute passage 60 and the communication passage 61 to the hollow portion.
The pressure is gradually released to 32, and eventually the decompression chamber for ignition fuel injection 22
Has the same internal pressure as the internal pressures P ₀ and P ₁ of the hollow portion 32 and the pump chamber 9. At this time, the pressure accumulation chamber 36 is depressurized to the pressure reduction chamber 20 from the maximum injection amount plus the amount of fuel leaked from the pump chamber 9 to the pressure accumulation chamber 36 through the ignition fuel injection pressure reduction chamber 22 and the like. The amount of fuel corresponding to the amount obtained by subtracting the amount of the remaining fuel is left, and the spool 29 is located at a position higher than the bottom dead center.

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

However, as described above, the amount of fuel stored in the pressure accumulating chamber 36 at the time t is the maximum amount of fuel that leaks from the pump chamber 9 to the pressure accumulating chamber 36 through the ignition fuel injection decompression chamber 22 and the like. Is an amount corresponding to the amount obtained by subtracting the amount of fuel depressurized in the decompression chamber 20 from the amount added with, 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. 36
The plunger 8 is surely returned to the top dead center by being discharged back to. Further, when the plunger 8 is returned to the top dead center at time v in this way, the pressure accumulating chamber from the pump chamber 9 through the ignition fuel injection depressurizing chamber 22 and the like is provided between the depressurizing chamber 20 and the pump chamber 9. Since the fuel equivalent to the amount leaking to 36 is confined excessively, the internal pressure of these is higher than the initial pressure at time v. Therefore, by opening the opening / closing valve 59 for adjusting the initial pressure from a predetermined time point w after the time point v to the time point x, the inlet valve 10 is opened.
The internal pressures of the hollow portion 32, the pump chamber 9, the pressure accumulating chamber 36, the valve opening pressure chamber 35, the valve closing pressure chamber 12 and the ignition fuel injection decompression 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 ignition injection start command valve 21 is composed of a double spool valve incorporated in the plunger 8.
That is, the child spool 68 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 68 has a through hole 63 having a reduced diameter at the lower end portion and a peripheral wall of a large diameter portion of the through hole 63 facing each other. And a valve hole 64 formed to 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, which communicate with the valve groove 53 when the child spool 68 rises to the top dead center, are formed on the peripheral wall of the lower end of the spool 29, and the plunger 8 has the spool 29. The injection depressurizing passages 52, 54 are formed to communicate with the valve holes 65, 66 of the spool 29, respectively, when they are located at a height in a predetermined range slightly lower than the top dead center. The other structure is the same as that of the above-described embodiment, and the description thereof is omitted.

In this implementation order, 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 is sucked out to the depressurizing chamber 20 through the through hole 63. Is
Although the spool 29 descends, since the through hole 63 has a reduced diameter portion, a pressure difference is generated between the pressure accumulating chamber 36 and the hollow portion 32, and the child spool 68 is raised at the same time when the spool 29 descends. When the child spool 68 reaches the top dead center, the injection start depressurizing passages 52, 54 of the plunger 8, the spools 65, 66 and the valve groove 53 of the child spool 68 communicate with each other, and the ignition injection start command valve 21 Is opened, and the pump chamber 9 is ignited by the fuel injection pressure reducing chamber 22.
The internal pressure of the pump chamber 9 and the valve closing pressure chamber 12 is reduced by communicating with the pump chamber 9.

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

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an inlet valve of a fuel injection pump for a pressure-accumulation fuel injection device according to the present invention when fuel is supplied from a pressure-feed pump to a fuel injection pump, and FIG. 2 is the pressure-accumulation fuel injection device in an initial state. 3 is a longitudinal sectional view of a unit injector of FIG. 3, FIG. 3 is an equivalent circuit diagram of the pressure-accumulation fuel injection device, FIG. 4 is a timing diagram showing operation timings of main parts of the pressure-accumulation fuel injection device, and FIG. FIGS. 6 (A) to 6 (D) are views showing the operation sequence of the plunger (8), which is a longitudinal sectional view of a main part of another embodiment. 4 ... Metering device, 5 ... Pressure pump, 6 ... Fuel injection pump, 7 ... Accumulation type fuel injection device, 8 ... Plunger,
9 ... Pump room, 10 ... Inlet valve, 23 ... Body, 28 ...
Valve chamber, 29 …… Spool, 30 ・ 31 …… Inlet passage part, 30a
...... Lower edge, 32 …… Hollow part, 33 …… Inlet valve hole, 34 …… Outlet hole, 35 …… Valve opening pressure chamber, 36 …… Stroke adjusting pressure accumulating chamber,
37 …… communication passage, 38 …… passage, 38a …… lower edge, 41 ・ 48 ……
Accumulation chamber for stabilizing biasing force, 46 ... Pressure transmission path, 46a ... Lower edge, 57 ... Fuel supply valve, 62 ... Upstream passage, 62a ... Lower edge, 80 ... Fuel injection cam, 84/85 ... passage, B ... fuel supply stroke, C ... fuel injection stroke, D ₁ , D ₂ ... bottom dead center, U ₁
・ U ₂ …… Top dead center, UO …… Upper dead center upper position, V ₂ …… Part of fuel in pump chamber 9, V ₃ …… Remaining fuel, a …… Valve opening start time, y… Discharge drive start time, z: Period after start of fuel supply and before start of discharge.

Claims (1)

[Claims] 1. A fuel metering device (4) for metering fuel according to a load of a diesel engine, and a metering pump (5) for metering the fuel to a fuel supply valve (57) and an inlet valve (10). The fuel injection pump (6) is then supplied to the fuel injection pump (6).
The fuel injection pump (6) has a pump chamber (9), a plunger (8) inserted in the fuel injection pump (6) so as to be able to move forward and backward, and a pump chamber when discharging. Inlet valve (1 to prevent backflow from (9) to the upstream side
0) and the valve chamber (2) of the inlet valve (10) in the plunger (8).
8) forming the spool (2) built into this valve chamber (28)
9) allows the valve opening pressure chamber (35) to open in the upper part of the valve chamber (28).
At the bottom of the valve chamber (28) for adjusting stroke (3
6) are respectively formed into compartments, the spool (29) is formed into a cylindrical shape with its upper end closed, and the hollow portion (32) of this spool (29) is formed in the peripheral wall of the spool (29). Inlet passage part (30) formed in the peripheral wall of the part (31) and the plunger (8)
Via an upstream side passageway (62) formed in the body (23) of the fuel injection pump (6) via the inlet valve (10), and the inlet valve (10) includes an inlet valve hole (33) and an outlet hole (34). Of the inlet valve hole (3
3) is formed in the lower part of the peripheral wall of the spool (29), and its outlet hole (34) is formed in the lower part of the peripheral wall of the plunger (8), and the outlet hole (34) is different from the inlet valve hole (33). The spool (29) communicates when the spool (29) is positioned below a predetermined height slightly lower than the top dead center (U ₂ ), whereas the spool (2
When the spool (29) is located at the top dead center (U ₂ ), the hollow portion (32) and the valve opening pressure chamber (35) are configured to be shut off when the spool 9 is located at a position higher than that. Communication passage (3
7) is formed on the upper part of the peripheral wall of the spool (29), and when the spool (29) is located at the bottom dead center (D ₂ ), the hollow part (32) is formed.
And the valve opening pressure chamber (35) are communicated with each other through the passages (84) (85) (38), the passage (38) of which is formed on the peripheral wall of the plunger (8). The above passage (38) and body (23) in (35)
The pressure accumulating chambers (41) (48) for stabilizing the urging force are connected via the pressure transmission path (46) formed in, and the spool (29) is located at the bottom dead center (D ₂ ) in the combustion supply stroke (B). Then, from the state where the plunger (8) is located at the top dead center (U ₁ ), the fuel supply valve (57) is opened, and the fuel metered by the pressure regulator (4) is fed by the pressure pump (5). The fuel is supplied to the stroke adjusting pressure accumulating chamber (36) through the upstream side passage (62), the inlet passage portion (30), and the hollow portion (32), and pushes up the spool (29) from the bottom dead center (D ₂ ). In the press-fitting stroke (C), the plunger (8) is driven by the fuel injection cam (80) to discharge from the top dead center (U ₁ ) to the bottom dead center (D ₁ ) and a part of the fuel in the pump chamber (9) is discharged. (V2) is pressed into the stroke adjusting pressure accumulating chamber (36) through the inlet valve (10) in the first period of the discharge drive, pushing up the spool (29),
After closing the inlet valve (10), the remainder of the fuel (V ₃ ) in the pump chamber (9) is press-fitted into the pressure-accumulation fuel injection device (7) in the latter stage of its discharge drive. In the fuel supply device of the accumulator fuel injection device of a diesel engine, during the fuel injection process (C) after the valve opening start timing (a) of the fuel supply valve (57) during the fuel supply process (B). Of the fuel injection cam (80) after the start of fuel supply before the discharge drive start timing (y) at which the plunger (8) of the above (8) starts to descend from the top dead center (U ₁ ) ) Cam lift shape, the plunger (8) is configured to be excessively moved to a position above the top dead center (UO) above the normal top dead center position (U ₁ ). Is excessively moved to the upper dead center position (UO), on the one hand, Valve chamber (35) and the biasing force for stabilizing the accumulation chamber (41)
Plunger (8) passageway (38) to communicate with (48)
In the pressure transmission path (46) of the body (23) of the fuel injection pump (6), the lower edge (38a) of the passage (38) is located above the lower edge (46a) of the pressure transmission path (46). By deviating, the cross-sectional area of the passage in the communicating portion between the passage (38) and the pressure transmission passage (46) is reduced, and on the other hand, the lower edge (30a) of the inlet passage portion (30) formed in the plunger (8) is reduced. ) Is biased above the lower edge (62a) of the upstream passage (62) formed in the body (23) of the fuel injection pump (6), and the upstream passage (62) and the inlet passage portion (30). ) Is configured to reduce a passage cross-sectional area in a communicating portion with the fuel supply device for a pressure-accumulation fuel injection device for a diesel engine.