JPH0735759B2 - Accumulator fuel injection system for engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a pressure accumulating fuel injection device for an engine.

<Prior invention> The pressure accumulating fuel injection device for an engine of the present invention is, for example, the first
As shown in FIGS. 3 to 3, it is premised on the prior invention configured as follows.

This prior invention was invented by the inventor of the present invention prior to the present invention.

◎ Structure That is, the fuel tank 20, the metering device 23, and the push pump 24
・ The switching valve V, the spool valve 12, the injection pump chamber 9, the valve closing pressure chamber 5, the check valve 8, the pressure accumulating chamber 6, and the injection valve 3 are connected in this order to the injection port 1, and the injection valve 3 is closed. A spring closing force of the spring 38 elastically pushes the valve toward the valve closing side, and a piston 4 is provided on the valve shaft of the injection valve 3 between the valve closing pressure chamber 5 and the check valve 8. The pressure in the chamber 5 is received to generate a pressure receiving valve closing force to press the injection valve 3 toward the valve closing side, while the pressure in the pressure accumulating chamber 6 is received to generate a pressure receiving valve opening force to perform injection. The valve 3 is configured to be pressed toward the valve opening side, and the remaining differential pressure opening force obtained by subtracting the pressure receiving valve closing force from the pressure receiving valve opening force of the piston 4 is the spring closing valve of the valve closing spring 38. If the force is smaller than the force, the injection valve 3 is closed, whereas if it is larger than the force, the valve is opened. Communicates the suction pump 45 via the Le valve 12, and the switching valve V, the changeover valve V, to the spool valve 12, pushing the pump
Push pump connection position to connect 24 and suction pump
It is configured to sequentially switch to the suction pump connection position for connecting 45, and the spool valve 12 is configured so that the spool 26 in the spool chamber 27,
It is configured to press the valve closing side by the accumulated valve closing force due to the accumulated pressure in the valve closing pressure accumulating chamber 43, while pressing it toward the valve opening side by the bias valve opening force due to the elastic pressure in the bias chamber 36. The valve closing pressure accumulating chamber 43 is communicated with the injection pump chamber 9 through the valve holes 33 and 32 of the spool valve 12, and the spool 26 is
While the valve holes 33 and 32 are separated from each other in the state of reaching the valve closing end, the valve is closed, while the valve hole 33, 32 moves from the valve closing end to the valve opening end, The holes 33 and 32 meet each other to open the valve.

The switching valve V is operatively connected to the crankshaft of the engine simply via the timing transmission device. This allows
The switching timing of the switching valve V is always constant with respect to the rotation angle of the crankshaft of the engine.

◎ Operation 1. From fuel supply to injection Refer to FIGS. 1 to 3 First, with the switching valve V in the push pump connection position,
The fuel in the fuel tank 20 is metered by the metering device 23 to an amount according to the load of the engine, is pressure-fed by the pushing pump 24, and is supplied to the injection pump chamber 9 through the switching valve V / spool valve 12. Here, the pressure is increased by the plunger 10, and the pressure is accumulated in the pressure accumulating chamber 6 through the valve closing pressure chamber 5 and the check valve 8.

At the end of this pressure accumulation, the check valve 8 is closed and the valve closing pressure chamber 5 is closed.
Has a high pressure that is substantially equal to the pressure stored in the pressure storage chamber 6. Therefore, the differential pressure valve opening force acting on the piston 4 due to the pressure difference between the pressure accumulating chamber 6 and the valve closing pressure chamber 5 becomes smaller than the spring valve closing force by the valve closing spring 38, and this difference force causes the injection valve 3 Closes the valve to keep the pressure accumulating chamber 6 in a pressure accumulating state.

Next, when the switching valve V is switched to the suction pump connection position, the pressure in the valve closing pressure chamber 5 is released to the suction pump 45, and the differential pressure valve opening force is larger than the spring valve closing force. Then, the injection valve 3 is opened. The fuel accumulated in the pressure accumulating chamber 6 is injected from the injection port 1 into the fuel chamber of the engine.

When the fuel injection progresses and the internal pressure of the pressure accumulating chamber 6 decreases to the valve closing set pressure, the differential pressure valve opening force becomes smaller than the spring valve closing force, and the injection valve 3 is closed to inject the fuel. Is over.

◎ Operation 2. Spool valve / plunger operation Refer to FIGS. 12 (A) to (D). FIGS. 12 (A) to (D) show each operation stroke of the spool valve 26 and the plunger 10 during one cycle. It operates in the following order.

(1) Metering fuel supply process state of FIG. 12 (A) The fuel of the full stroke amount V ₅ is completely injected from the valve closing pressure accumulating chamber 43 into the injection pump chamber 9. This allows
The plunger 10 is pushed back from the discharge end position 61 to the return end position 62 and pressed against the base circular surface 66 of the fuel injection cam 65.

The accumulated pressure in the valve-accumulation chamber 43 is equal to that of the spool 26 of the spool valve 12.
Is lower than the valve closing set pressure of, and the spool 26 is opened by the bias valve opening force due to the elastic pressure in the bias chamber 36.

The fuel of the metering supply amount V ₁ that has been metered and pumped according to the load of the engine is press-fitted into the valve closing pressure accumulating chamber 43. As a result, the accumulated pressure in the valve closing pressure accumulating chamber 43 increases, but the valve closing set pressure of the spool 26 has not yet been reached, and the spool 26 remains open.

(2) Invalid discharge stroke state of FIG. 12 (B) With the switching valve V closed with respect to the spool valve 12, the lift-up surface 67 of the fuel injection cam 65 drives the plunger 10 to discharge. Flow stroke amount in injection pump chamber 9 V ₅
When a partial amount (ineffective discharge amount) V ₂ of the fuel is sent back into the valve closing accumulator chamber 43, the valve closing accumulator chamber
The fuel in 43 becomes the full pressure accumulation amount V ₄ (equal amount to the above-mentioned full stroke amount V ₅ ) and the pressure accumulation in the valve closing pressure accumulation chamber 43 and the injection pump chamber 9 is increased to the valve closing set pressure of the spool 26. hand,
Close the spool 26.

(3) Effective discharge stroke The state of Fig. 12 (C) The plunger 10 is continuously driven to discharge, and the injection pump chamber 9
The remaining amount (effective discharge amount) V ₃ of the fuel is discharged and injected into the pressure accumulating chamber 6 from the check valve 8.

This effective discharge amount V ₃ becomes the same amount as the metering supply amount V _{1 according} to the following equation.

Condition V ₅ = V ₂ + V ₃ V ₄ = V ₁ + V ₂ V ₅ = V ₄ Calculation formula V ₅ = V ₂ + V ₃ = V ₄ = V ₁ + V ₂ V ₅ −V ₂ = V ₃ = V ₄ −V ₂ = V ₁ Answer ∴ V ₃ = V ₁ (4) Plunger return stroke Fig. 12 (D) State The working surface of the fuel injection cam 65 changes from the lift top surface 68 to the lift down surface 69 to the base circular surface 66. Move on.

Then, immediately, the pressure in the injection pump chamber 9 is lowered to become lower than the valve closing set pressure of the spool 26,
26 opens.

The fuel of the full accumulated pressure V ₄ in the valve closing accumulator 43 is stored in the spool 26
After that, the fuel is press-fitted into the injection pump chamber 9 and becomes the fuel of the full stroke amount V ₅ . As a result, the plunger 10 is pushed back from the discharge end position 61 by the full stroke and is returned to the return end position.
It reaches 62 and abuts the base circular surface 66 of the fuel injection cam 65.

◎ Advantages of plunger return For this reason, at the time of the next discharge drive of the plunger 10, the fuel injection cam 65 and the plunger 10 are always in contact with each other, and no gap is created. The problems such as impact sound, abnormal wear, deformation and damage due to are solved.

<Problems to be Solved by the Invention> The preceding invention has the following problems.

(B) Advance control of fuel injection timing The valve switching timing of the switching valve V is always constant with respect to the rotation angle of the crankshaft of the engine.

Therefore, the timing at which the pressure in the valve closing pressure chamber 5 is released from the switching valve V to the pump 45 is constant, the opening timing of the injection valve 3 is also constant, and the fuel injection timing is also constant. It is not possible to advance the fuel injection timing according to the rotation speed of the.

(B) Insufficient amount of combustion injection When the switching valve V is switched to the suction pump connection position, the pressure in the valve closing pressure chamber 5 is released to the suction pump 45 and reduced in pressure, and the injection valve 3 is opened. , Fuel injection is performed.

At this time, the pressurized fuel in the fuel-filled space from the valve closing pressure chamber 5 to the switching valve V via the injection pump chamber 9 and the valve closing pressure accumulating chamber 43 is used for depressurization required for depressurization. Since only the escape amount goes out to the suction pump 45 and is not returned to the fuel-filled space, the decompression escape amount becomes insufficient.

As a result, next time, the fuel of the effective discharge amount V ₃ becomes smaller than the fuel of the metering supply amount V _{1 by} the depressurizing escape amount, and the fuel injection amount becomes insufficient accordingly.

An object of the present invention is to enable advance control of fuel injection timing in a pressure-accumulation fuel injection system for an engine, and for a metered supply amount of fuel metered corresponding to an engine load, It is to eliminate the shortage of fuel injection amount.

<Means for Solving the Problems> In order to solve the above problems, the present invention adds the following characteristic structure to the above prior art structure, as shown in, for example, FIGS. 1 to 3. Characterize.

That is, the switching valve V is configured to be advanced by the timer mechanism 15 in accordance with the engine speed, and the switching valve V and the constant pressure supply circuit C are provided in the valve closing pressure accumulating chamber 43 of the spool valve 12. A constant pressure supply means E is connected via the switching valve V to the spool valve 12, and
It is configured to circulate and switch to the push pump connection position where 24 is connected, the suction pump connection position where the suction pump 45 is connected next, and the constant pressure supply circuit connection position where the constant pressure supply circuit C is connected. It is characterized by

<Operation> The present invention operates as follows.

(A) Advance control of fuel injection timing The timer mechanism 15 is operated to advance, and as the engine speed increases, the switching timing of the switching valve V is advanced with respect to the rotation angle of the crankshaft, and the suction is performed. Advance the timing of switching to the pump connection position.

As a result, the valve opening timing of the injection valve 3 is also advanced, the fuel injection timing is advanced, and the advance angle control is performed.

(B) Solving the shortage of the fuel injection amount After the fuel of the effective discharge amount V ₃ shown in FIG. 12 (C) has been discharged from the injection pump chamber 9, the plunger shown in FIG. 12 (D)
After the resetting operation of 10, the metering supply amount V ₁ shown in FIG.
The switching valve V is switched from the suction return pump connection position to the constant pressure replenishment circuit connection position within a period before starting to press-fit the fuel into the valve closing pressure accumulating chamber V ₁ .

Then, from the constant pressure supply circuit C, through the switching valve V, the fuel of the supply set pressure is injected into the fuel filling space composed of the valve closing pressure accumulating chamber 43, the injection pump chamber 9, and the closed space communicating with this. When the inside of the fuel-filled space has reached the replenishment set pressure, the fuel injection is completed.

In addition, the shortage of the pressure reducing escape amount of the pressurized fuel in the fuel-filled space described in the section “(b) Insufficient fuel injection amount” in the section <Problems to be solved by the invention> The supply pressure of the constant pressure supply circuit C is set so that the supply of the supply supply pressure from the constant pressure supply circuit C of the present invention equals the amount of supply of the fuel pressurization supply amount into the fuel filling space. It is set in advance.

As a result, the pressurized fuel in the fuel-filled space is replenished by the replenishment amount of the fuel pressurization replenishment amount only for the shortage of the depressurization escape amount, so that next time, the fuel of the effective discharge amount V ₃ is It is possible to solve the shortage of the fuel injection amount by preventing the amount of fuel supplied from the metering supply amount V ₁ from decreasing by the amount of the pressure reducing escape amount.

<Effects of the Invention> The present invention is configured and operates as described above,
It has the following effects.

(A) Advance control of fuel injection timing The timer mechanism 15 advances and retreats the valve opening timing of the injection valve 3 by advancing and retreating the switching timing of the switching valve V to the suction pump connection position according to the engine speed. The fuel injection timing is adjusted and the fuel injection timing is advanced.

As a result, the fuel injection timing of the pressure accumulation type fuel injection device can be advanced.

(B) No new research and development of a timer mechanism is required. In a general fuel injection device that is not a pressure accumulation type, a timer is used to adjust the fuel injection timing, and in particular, an automatic timer has become widespread.

Since a timer such as this existing automatic timer can be used as the timer mechanism 15 of the present invention, it is not necessary to newly research and develop the timer mechanism 15, and a high-performance timer mechanism can be easily obtained at low cost.

(C) Resolving shortage of fuel injection amount In the above-mentioned <Problems to be solved by the invention>, “(b) Insufficient fuel injection amount” The shortage of the depressurization escape amount and the amount of replenishment of the fuel pressure replenishing amount into the fuel filling space by the supply of the replenishment set pressure from the constant pressure replenishing circuit C of the present invention are equal to each other. The replenishment set pressure of the constant pressure replenishment circuit C is set in advance.

As a result, the pressurized fuel in the fuel-filled space is replenished by the replenishment amount of the fuel pressurization replenishment amount only for the shortage of the depressurization escape amount, so that next time, the fuel of the effective discharge amount V ₃ is It is possible to solve the shortage of the fuel injection amount by preventing the amount of fuel supplied from the metering supply amount V ₁ from decreasing by the amount of the pressure reducing escape amount.

<Examples> Examples of the present invention will be described below with reference to the drawings.

◎ Structure As shown in FIGS. 1 to 3, the pressure-accumulation fuel injection device of this engine has a unit injector U, a fuel supply circuit F for supplying fuel to the unit injector U, and a constant pressure supply circuit C,
An advance angle control circuit T is provided between the fuel tank 20 shared by the fuel supply circuit F and the constant pressure supply circuit C and the unit injector U.

The fuel supply circuit F, the constant pressure supply circuit C, and the advance control circuit T are connected to the spool valve 12 of the unit injector U by a switching valve V.

The fuel supply circuit F includes a fuel tank 20 and a constant pressure supply means E.
Has a fuel pump 21, a pressure regulator 22, a regulator (governor) 23, and a push-in pump 24, and is configured to supply the unit injector U with fuel of a predetermined pressure that is regulated in accordance with the engine speed. ing. The timing of this fuel supply is
It is determined by the switching valve V.

The unit injector U has a main body B as shown in FIG.
The injection pipe 2 is integrally assembled with the injection pipe 2, and a plurality of injection ports 1 are opened at the lower end of the injection pipe 2. This injection pipe 2
A needle valve 3 as an injection valve is arranged therein so as to be capable of advancing and retracting so as to open and close the injection pipe 2 in the vicinity of the injection port 1.

A piston 4 is formed on the valve shaft of the needle valve 3, and a closed valve pressure chamber 5 is formed in a portion of the injection pipe 2 opposite to the injection port 1, and a small capacity is formed in a portion of the injection pipe 2 on the injection port 1 side. First
The pressure accumulating chambers 6 are partitioned.

A communication passage 7 that connects the valve closing pressure chamber 5 and the pressure accumulation chamber 6 is formed between the piston 4 and the inner peripheral surface of the injection pipe 2, and the pressure accumulation chamber 6 side of the piston 4 is provided with an end face thereof. A check valve 8 is inserted which is brought into contact with and separated from the inner peripheral surface of the injection pipe 2, and the peripheral surface thereof is slidably contacted.

An injection pump chamber 9 is connected to the valve closing pressure chamber 5 via a communication passage 25.
Is connected, and the plunger 10 is inserted into this injection pump chamber 9 so as to be able to move forward and backward. A spool valve 12 that opens and closes an intake passage 11 to the injection pump chamber 9 is provided in the plunger 10.

That is, the plunger 10 is supported by the main body B so as to be able to move back and forth in the vertical direction, and the spool chamber 27 for accommodating the spool 26 therein.
Is formed.

This spool 26 has a hollow hole that extends from the lower end to the vicinity of the upper end.
Communication passages 29, 30 having the valve 28 and communicating with the switching valve V are formed at intermediate height portions of the spool 26 and the plunger 10.

Further, valve holes 31 and 32 for communicating the injection pump chamber 9 with the valve closing pressure accumulating chamber 43 below the spool chamber 27 are formed at a position slightly above the lower end of the plunger 10. A valve hole 33 corresponding to the valve holes 31 and 32 is penetrated through the peripheral wall of the spool 26 at a predetermined height from the lower end thereof.

Further, a bias passage 34 is formed on the peripheral wall of the spool 26 so as to communicate from the upper end of the hollow hole 28 to the peripheral surface. This bias road
34 is a bias chamber 36 above the spool chamber 27 and a valve closing spring chamber in the main body B via a passage 35 formed in the plunger 10.
Connected to 37.

The valve-closing spring chamber 37 is disposed above the valve-closing pressure chamber 5, and the upper end of the valve shaft of the needle valve 3 is made to project into the valve-closing spring chamber 37 so as to be able to move up and down. Further, in the valve closing spring chamber 37, a valve closing spring 38 for urging the valve shaft downward is inserted.

The first pressure accumulation chamber 6 is connected to a large capacity second pressure accumulation chamber 41 via a check valve 39 and a pressure setting valve 40 in parallel. The second pressure accumulating chamber 6 is formed in the body B in an annular shape surrounding the upper part of the valve shaft of the needle valve 3.

In the check valve 39, the internal pressure of the first pressure accumulating chamber 6 is, for example, 700 to 1
The valve is opened when the pressure is as high as 000 atm, and the fuel is configured to flow from the first pressure accumulation chamber 6 to the second pressure accumulation chamber 41.

The pressure setting valve 40 is opened when the internal pressure of the first pressure accumulating chamber 6 drops to a predetermined pressure higher than the valve closing pressure due to the opening of the needle valve 3, and the first pressure accumulating chamber 6 and the second pressure accumulating chamber 41 are opened. Valve closing spring 4 when the internal pressure reaches a predetermined valve closing pressure (for example, 270 atm)
Closed by 2.

In addition, one of the two valve holes 31, 32 formed in the plunger 10
1 is formed to have a much smaller diameter than the other valve hole 32, and is opened above the other valve hole 32 from the bottom dead center of the spool 26.

The constant pressure supply circuit C is branched from the fuel supply circuit F downstream of the pressure regulator 22. The advance control circuit T includes a switching valve V whose valve opening timing is controlled by a timer mechanism 43 and a suction pump 45.
It has and.

The suction pump 45 includes a plunger 47 inserted into the plunger chamber 46 so as to be able to move forward and backward, and the plunger 47.
It is composed of a spring 48 for urging in a direction in which the volume of 46 expands, and is driven by a cam that interlocks with a crank shaft (not shown).

Incidentally, 50 is a valve closing spring of the check valve 8 and 51 is a valve closing spring of the check valve 39.

◎ Operation In the above-mentioned configuration, at the time point a in FIG. 11 when fuel is supplied to the unit injector U, the spool 2 is located at the bottom dead center and the plunger 10 is located at the top dead center as shown in FIG. Located.

At this time point a, the spool valve 12 is opened and the check valve 8,
The check valve 39 and the pressure setting valve 40 are closed, and the bias chamber 36 communicates with the hollow hole 28 of the spool 26.

When fuel is started to be supplied while the plunger 10 is positioned at the top dead center from this point a, the spool 26 rises from the bottom dead center, and as shown in FIG.
The hollow hole 28 in 26 is cut off, and the spool is placed at a position where the pressures in the bias chamber 36 and the valve closing accumulator chamber 43 are balanced at time b.
26 stops and the fuel supply is terminated.

At the time point c in FIG. 11, the fuel injection cam 65 shown in FIG. 12 starts lowering the plunger 10. As a result, the volume of the injection pump chamber 9 starts to decrease. As the volume decreases, fuel flows from the injection pump chamber 9 into the pressure accumulating chamber 43 through the valve holes 31 and 32, and the spool 26 rises again. This spool 26
The internal pressures of the valve closing pressure chamber 5, the injection pump chamber 9 and the pressure accumulating chamber 3 rise while the pressure rises.

Eventually, the state shown in FIG. 5 is reached, the spool valve 12 is closed at the time point d in FIG. 11, and the internal pressure of the valve closing pressure accumulating chamber 43 becomes constant. At this time point d, the check valve 8 is opened, the plunger 10 is further lowered, and the internal pressures of the valve closing pressure chamber 5, the injection pump chamber 9 and the first pressure accumulating chamber 6 are further increased.

After the time point e when the pressure becomes equal to or higher than a predetermined pressure, the check valve 39 is opened, the plunger 10 reaches the bottom dead center as shown in FIG. 6, and the valve closing pressure chamber 5, the injection pump chamber 9, and the first accumulator chamber are reached. As shown in FIG. 7, the check valve 8 and the check valve 39 are closed at the time point f when the internal pressures of 6 and the second pressure accumulating chamber 41 are balanced.

After this, the switching valve V is switched to move the suction passage 11 through the advance control circuit T.
, The internal pressure of the hollow hole 28 of the spool 2 and the pressure accumulating chamber 43 decreases, while the spool 26 descends due to the pressure difference between the bias chamber 36 and the pressure accumulating chamber 43.

As shown in FIG. 8, the internal pressure of the valve closing pressure chamber 5 gradually decreases from the time point h when the small diameter valve hole 31 is connected to the valve hole 33.
Due to this interlocking, the differential pressure acting on the piston 4 gradually increases.

The needle valve 3 is gradually opened from the time point i where the differential pressure overcomes the internal pressure of the valve closing spring chamber 37 acting on the needle valve 3 and the force of the valve closing spring 38. As a result, fuel injection is performed, but at this stage, only a small amount of fuel in the first pressure accumulating chamber 6 is injected, and the injection rate is suppressed to a low level.

As a result, the rising of the spool 26 at the time of ignition continues further, and at time j after the large-diameter valve hole 32 communicates with the valve hole 33 almost at the same time as the ignition, the internal pressure of the valve closing pressure chamber 5 decreases more rapidly, and
As shown in the figure, the needle valve 3 is further opened.

Although the internal pressure of the first pressure accumulating chamber 6 is further reduced by this valve opening,
The pressure setting valve 40 opens, and a large amount of fuel is ejected from the second pressure accumulation chamber 41 via the first pressure accumulation chamber 6 and the injection port 1.

When the internal pressures of the first pressure accumulating chamber 6 and the second pressure accumulating chamber 41 drop to a predetermined value, the differential pressure acting on the piston 4 decreases and the valve closing spring
At time k when the pressure acting on the valve shaft from the valve closing valve 38 and the valve closing spring chamber 37 becomes larger than the pressure difference acting on the piston 4, the needle valve 3 is closed and the fuel injection is completed.

After this, the plunger 10 rises from the bottom dead center to the top dead center from the time point l to the time point m. The spool 26 descends to an intermediate height by the end of fuel injection, as shown in FIG. 11 (2), but further descends to the bottom dead center when the plunger 10 rises, and moves the plunger 10 from the bottom dead center. Push it up to top dead center.

In the above-described embodiment, the valve holes 31 and 32 are formed as large and small circular holes as shown in FIG. 10 (1). For example, as shown in FIG. 10 (2), the circular holes 32 and 32 And a small groove 31 that is continuous with each other. For example, as shown in FIG. 10 (3), it may be an egg-shaped hole in which a small diameter portion 31 and a large diameter portion 32 are continuous. .

[Brief description of drawings]

FIG. 1 is an equivalent circuit diagram of an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of a lead angle device of a pressure accumulation type fuel injection device, and FIGS.
The figure is a longitudinal sectional view showing the operating state of the unit injector in order, Fig. 10 (1) is a front view showing the valve hole of the plunger, and Fig. 10 (2) and 10 (3) are the valve holes of the plunger, respectively. It is a front view which shows the modification. (1) to (6) of FIG. 11 are time charts showing the action of each part. FIG. (1) shows a change in internal pressure of the valve closing pressure accumulating chamber under the spool chamber, and FIG. (2) shows a change of spool position. (3) is the position change of the plunger, (4) is the internal pressure change of the injection pump chamber, (5) is the lift amount change of the needle valve, (6)
Shows the internal pressure change and the fuel injection rate change of the first pressure accumulating chamber and the second pressure accumulating chamber, respectively. 12 (A) to 12 (D) are operation stroke diagrams showing the respective operation strokes of the spool valve and the plunger in order, FIG. 12 (A) is a metering fuel supply stroke chart, and FIG. 12 (B) is the invalid discharge stroke. The figure, figure (C) is an effective discharge stroke diagram, and figure (D) is a plunger return stroke diagram. 1 ... Injection port, 3 ... Injection valve (needle valve), 4 ... Piston, 5 ... Closed pressure chamber, 6 ... Accumulation chamber, 8 ... Check valve, 9 ... Injection pump chamber, 10 ... … Plunger, 12 …… Spool valve, 15 …… Timer mechanism, 20 …… Fuel tank, 23…
… Metering device, 24 …… Push pump, 26 …… Spool, 27…
… Spool chamber, 32 ・ 33 …… Valve hole, 36 …… Bias chamber, 38
...... Valve closing spring, 43 ...... Valve closing pressure chamber, 45 ...... Suction pump, C ...... Constant pressure supply circuit, E ...... Constant pressure supply means, V ......
Switching valve

Claims (1)

[Claims] 1. A fuel tank (20) having a metering device (23), a pushing pump (24), a switching valve (V), a spool valve (12), an injection pump chamber (9), and a valve closing pressure chamber (5). ) ・ Check valve (8) ・
The injection port (1) is communicated through the pressure accumulating chamber (6) and the injection valve (3) in order, and the injection valve (3) is elastically pressed toward the valve closing side by the spring closing force of the valve closing spring (38). A piston (4) is provided on the valve shaft of the injection valve (3) between the valve closing pressure chamber (5) and the check valve (8), and the piston (4) is inside the valve closing pressure chamber (5). To generate a pressure receiving valve closing force to press the injection valve (3) toward the valve closing side, while receiving a pressure in the pressure accumulating chamber (6) to generate a pressure receiving valve opening force, The injection valve (3) is configured to be pressed toward the valve opening side, and the differential pressure opening force remaining after subtracting the pressure receiving valve closing force from the pressure receiving valve opening force of the piston (4) is the valve closing spring. (3
If it is smaller than the spring closing force of 8), the injection valve (3)
Is closed, whereas it is opened when it is large, and the valve closing pressure chamber (5) is connected via the plunger chamber (9), the spool valve (12), and the switching valve (V). The suction pump (45) communicates with each other, and the switching valve (V) is connected to the spool valve (12) by a push pump connecting position where the push pump (24) is connected.
The spool valve (12) is configured to be sequentially switched to the suction pump connection position to be connected to the suction pump (45), and the spool valve (12) has the spool (26) in the spool chamber (27) and the valve closing pressure accumulation chamber (43). Bias chamber (3
The bias valve opening force due to the elastic force in 6) pushes the valve to the valve opening side. The valve closing pressure accumulating chamber (43) is formed in the valve holes (33) and (32) of the spool valve (12). Through the injection pump chamber (9), and the spool (26) reaches the valve closing side end, and the valve holes (33) and (32) are separated from each other to close the valve. On the other hand, from the state of moving from the valve closing side end to the valve opening side end, the valve holes (33) and (32) meet each other to open the engine. In the pressure-accumulation fuel injection device, the switching valve (V) is configured to adjust the advance angle according to the engine speed by a timer mechanism (15), and the valve-accumulation chamber for closing the spool valve (12) ( 43) is connected to a constant pressure supply means (E) via a switching valve (V) and a constant pressure supply circuit (C), and the switching valve (V) is a spool valve (12). In contrast, the push-pump connection position to first connect the push pump (24),
An engine characterized by being configured so as to sequentially circulate and switch to the suction pump connection position to which the suction pump (45) is connected, and then to the constant pressure supply circuit connection position to which the constant pressure supply circuit (C) is connected. Accumulator fuel injection device.