JPS59162356A - Fuel injection device - Google Patents

Abstract

PURPOSE:To obtain the optimum injection pressure suited for an operating condition by controlling a control valve with pressure in a pressure feed pump chamber so as to adjust the back pressure, and relatively increasing injection pressure in the low rotation range, while relatively reducing the injection pressure in the high rotation range. CONSTITUTION:As a pressure feed plunger 12 is lowered, the pressure in the pressure feed pump chamber 13 rises. The pre-flow pressure in the pressure feed pump chamber 13 before the main reed 28 of the pressure feed plunger 12 closes a feed port 17, a pressure receiving port 60, and a pressure adjusting port 61, acts on a pressure adjusting chamber 63 through the pressure receiving port 60 and a pressure adjusting passage 62, depressing a nozzle spring seat 64. Thereby, a nozzle spring 54 is deflected increasing the valve opening pressure of a needle valve 51, while a rod 64a approaches the needle valve 51, restricting the amount of the lift of the needle valve 51.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection device for supplying fuel to a diesel engine or the like.

In recent years, with the improvement of combustion characteristics of diesel engines, there has been a demand for increasing fuel injection pressure. For this purpose, the cam that rotates in synchronization with the engine operates the pressure-feeding granger via the cam follower, pressurizes the fuel in the pressure-feeding pump chamber by the pressure-feeding sylanger, and injects the fuel by the hydraulic pressure in the pressure-feeding pump chamber. The development of a device that operates a plunger to pressurize fuel in an injection pump chamber and supplies this high-pressure fuel to an injection nozzle to perform high-pressure injection is underway.

In this case, the amount of fuel injected needs to be controlled based on the engine operating conditions, such as engine speed and load, so the injection pump chamber is filled with fuel that has been adjusted in advance to match the engine operating conditions. The metered fuel is pressurized to a high pressure by the injection sill/jar and injected from the injection nozzle.

However, in such a fuel injection device, the pressure plunger is driven by a cam on the engine side, so due to the characteristics of the cam, the fuel pressure generated in the pressure pump chamber is low when the engine is running at low speeds, and low when the engine is running at high speeds. Fuel pressure tends to increase. The above fuel injection device has the advantage of being able to relatively increase the injection pressure, but in the low engine speed range the injection pressure is lower than the required pressure, which may result in insufficient atomization of the fuel. On the other hand, in the high rotation range of the engine, the injection pressure becomes too high, resulting in poor performance in terms of fuel consumption, exhaust gas, noise, torque, etc.

The present invention was made based on the above circumstances, and its purpose is to relatively increase the injection pressure in the low engine speed range and to relatively lower the injection pressure in the high engine speed range. The present invention aims to provide a fuel injection device that can obtain the optimum injection pressure suitable for engine operating conditions.

That is, the present invention introduces a part of the fuel pressurized in the pressure pump chamber as a back pressure that acts as a resistance to opening the control valve and the injection nozzle, and controls the opening amount of the control valve according to the pressure in the pressure pump chamber. The invention is characterized in that the back pressure of the injection nozzle is controlled by controlling the back pressure of the injection nozzle, thereby changing the valve opening pressure of the injection nozzle, so that the injection pressure can be adjusted.

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

In the figure, 1 indicates a unit injector, and this unit injector 1 is fitted into a mounting hole 3 formed in a cylinder head 2 of a diesel engine. There is an O-ring 4 between the unit injector 1 and the cylinder head 2.
. . . An annular main gear rally 5 divided into sections is formed.

The unit injector 1 is assembled by integrally connecting a pressure cylinder 6, an injection cylinder 7, and a nozzle holder 8 with a holder nut 9 screwed onto the pressure cylinder body 6. Incidentally, on the inner surface of the holder nut 9, an annular sub-gear rally 10 is formed, with the above-mentioned pressure-feeding cylinder located between the die 6 and the injection cylinder 7, and this sub-gear rally 10 has a plurality of through holes 11...
It communicates with the main gear rally 5 through.

A pressure plunger 12 is slidably inserted into the pressure cylinder head 6 and forms a pressure pump chamber 13 . The pressure-feeding plunger 12 is connected to a cam 7 follower 14, and the cam follower 14 is driven downward in the drawing by a cam rotating in synchronization with an engine (not shown), either directly or indirectly via a rocker arm or the like. Between the cam follower 14 and the pressure-feeding cylinder body 6, a 7-lower spring 15 is mounted.
5, the cam follower 14 and the pressure-feeding silane gloss 12
is returned upwards. Note that 16 is an air vent hole. A feed port 17 is opened on the inner surface of the pressure-feeding cylinder body 6, and this feed port 17 communicates with the sub-gearry 10. A timing port 18 is opened above the feed port 17 in the drawing. This timing port 18 communicates with a solenoid valve mechanism 20 via a timing passage 19. The electromagnetic valve mechanism 20 operates a spool valve 22 by a solenoid 21, and when the solenoid 21 is energized, the spool valve 22 connects the timing passage 19 to the drain passage 23. The drain passage 23 communicates with the sub-gearry 10. The solenoid valve mechanism 20 is operated by a control circuit 100 such as a computer, which will be described later.

A metering passage 25 connected to the supply port 24 is formed in the pressure-feeding cylinder body 6, and this metering passage 25 communicates with a metering port 26th. Another metering port 26b is formed opposite to these metering ports 2, 6a.
b is connected to the injection pump chamber 3, which will be described later, via another metering passage 27.
It is connected to 7.

A main lead 28 is formed on the lower surface of the pressure-feeding plunger 12, and this main lead 28 is connected to the pressure-feeding plunger 1
2, the timing port 18 and feed port 17 are closed. Further, an annular groove 30 is formed in the pressure-feeding plunger 12, and a timing lead 31 for opening and closing the timing port 18 is provided in the annular groove 30.
and a spill lead 32 are formed. This annular groove 30 is connected to the pressure pump chamber 1 through a horizontal hole 33 and a vertical hole 34.
It is connected to 3. Furthermore, a metering annular groove 35 is formed in the pressure-feeding plunger 12 to allow the metering ports 26a, 2'6'b to be electrically connected to each other. An injection syringer 36 is slidably inserted into the injection cylinder 7 to form an injection chamber 37. The injection silane gloss 36 is also formed to have a smaller diameter than the pressure feeding plant gloss 12. A pressure receiving chamber 38 communicating with the pressure pump chamber 13 is formed on the upper surface side of the injection plunger 36 . A spill port 39 is formed in the injection cylinder 7, and this spill port 39 communicates with the aforementioned metering passage 25 via a spill passage 40.

Also, a drain port 41 is formed above the spill port 39, and this drain port 41 is located above the spill port 39.
This leads to sub-gearry 10. Injection plunger 3
6 is also formed with an annular groove 42, and the lower surface of this annular groove 42 forms a spill lead 43 for opening and closing the spill port 39. This annular groove 42 has horizontal holes 44 and vertical holes 45.
It communicates with the injection pump chamber 37 via.

Note that the upper surface of the injection plunger 36 forms a drain lead 46 that opens and closes the drain port 41.

The injection pump chamber 37 communicates with the metering passage 27 and also with the fuel passage 47.

This fuel passage 47 communicates with an injection nozzle 50 attached to the nozzle holder 8 described above. The injection nozzle 50 is supported by the nozzle holder 8 by a retainer nut 56, and this injection nozzle 50 is known in the art. Depending on the fuel pressure, the needle valve 51 is connected to the nozzle spring 52.
Since the nozzle hole 53 is opened against the pressure, the fuel is injected from this nozzle hole 53. The nozzle spring 52 is attached to the nozzle holder 8
The nozzle spring chamber 54 is housed in a nozzle spring chamber 54 formed in the nozzle spring chamber 54. This nozzle spring chamber 54- communicates with the sub-gearry 10 via a drain passage 55.

Therefore, the pressure-feeding plunger 1 is provided in the pressure-feeding pump chamber 13.
A pressure receiving port 60 and a pressure regulating port 61 which are opened and closed by the main lead 28 and the spill lead 32 of No. 2 are opened. The pressure receiving port 60 communicates with a pressure regulating chamber 63 via a pressure regulating passage 62 . A spring seat 64 facing the nozzle spring chamber 54 is slidably fitted into the pressure regulating chamber 63 . This spring seat 64 supports the upper end of the nozzle spring 52, and the pressure adjustment chamber 6
3 increases and pushes down the spring seat 64, the nozzle spring 52 bends accordingly, and the force pushing down the needle valve 51 increases. Therefore, the needle valve 51 has a higher starting pressure, in other words, a higher opening opening pressure, and therefore fuel is fed from the fuel passage 47 at a higher pressure than the above-mentioned predetermined opening pressure.

Otherwise, the valve will not open. Therefore, the pressure regulating chamber 63 generates back pressure that acts as a resistance to opening the injection nozzle 50.

The pressure regulating port 61 is a control valve chamber 6 formed in the injection cylinder 7.
5. The control valve chamber 65 has a control valve 66 driven by the pressure introduced through the pressure regulating port 6.
is slidably inserted. This control valve 66 is always urged upward by a spring 67. A spill port 68 is opened at a lower position in the control valve chamber 65 9 , and this spill port 68 communicates with the sub-gearry 10 . In addition, a spill port 68 is also located above the control valve chamber 65, and a first port 69 and a second port 2 are connected to each other.
0 are formed opposite each other. The first port 69 communicates with the metering passage 62, and the second port 70 communicates with the sub-gearry 10. Furthermore, a drain port 71 is opened in the control valve chamber 65 at an upper position, and this drain port 71 is connected to the sub gear 1
Connected to 0.

The control valve 66 is formed with an annular groove 72 for opening and closing the first port 69 and the second port 70, and a drain lead 73 for opening and closing the drain port 7 is formed on the upper end surface.

80 shown in FIG. 1 is a first feed pump, which handles fuel from a fuel tank 81 and transfers this fuel to a pressure regulating valve 82.
The fuel is regulated to a predetermined pressure by the pressure control and fed to the main gear gallery 5 via the feed passage 83 and the filter 84. Note that an overflow passage 85 is communicated with the main gear rally 5, and this overflow passage 85 returns surplus fuel in the main gear rally 5 to the fuel tank 81 via a throttle valve 86 and a check valve 87. .

A second feed pump 90 handles fuel from the fuel tank 8 , regulates this fuel to a predetermined pressure by a pressure regulating valve 91 , and sends it to a surge tank 92 . The surge tank 92 stabilizes the fuel pressure by the achievator 93,
This fuel is sent through a passage 94 and a filter 95 to a metering solenoid valve 96 as a metering device. The metering solenoid valve 96 is opened and closed by a signal from the aforementioned control circuit 100, and the amount of fuel to be injected is regulated by the opening time of the metering solenoid valve 96. The fuel metered by the metering solenoid valve 96 is sent to the supply port 24 of the unit injector 1 via a passage 97, a throttle valve 98, and a check valve 99. And the metering fuel with the metering annular groove 35 is the metering port 2.
6th, 26b are electrically connected, the metering passage 26
, the metering port 26a, the metering annular groove 3'5, the metering port 26b, and the metering passage 27 to the injection pump chamber 37.

The control circuit 100 receives engine speed, accelerator pedal depression amount, engine temperature, surge tank pressure, and other engine operating conditions as signals from sensors (not shown), and based on these signals, determines the opening time and amount of the metering solenoid valve 96. It calculates the closing timing of the electromagnetic valve mechanism 20 and gives command signals to these electromagnetic valves.

The operation of the embodiment with such a configuration will be explained.

When the pressure pump chamber 13 is at the top dead center, fuel is filled into the pressure pump chamber 13 from the feed port I7 via the main gear rally 5, the through hole 11, . . . the sub gear gear 10. At this time, the metering annular groove 35 conducts the metering ports 25a and 25b, and the fuel metered by the metering solenoid valve 96 is injected from the metering passage 27 in accordance with the operating condition of the engine. It is fed into the pump chamber 37. Therefore, the injection syringer 36 moves upwards depending on the metered fuel in the injection pump chamber 37.
It is pushed up and filled. When the cam follower 14 is pushed down by the operation of a cam (not shown), the pressure-feeding syringe 1
2 also descends together and feeds the fuel in the pressure pump chamber 13? -) Discharge from 77. When the main lead 28 of the pumping granger 12 closes the feed port 17, the spill lead 32 opens the timing port 18. In this case, before the main lead 28 closes the feed port 17, the solenoid 21 of the electromagnetic valve mechanism 20 is energized to open the spool valve 22, thereby establishing continuity between the timing passage 19 and the drain passage 23. .

Therefore, the spill lead 32 is the timing boat 1.
When 8 is opened, fuel is discharged through the vertical hole 34, horizontal hole 33, annular groove 3θ and timing boat 18 in the pressure pump chamber 13. Then, when a command is received from the control circuit 100 to set the optimum injection timing according to the engine speed, load, etc., the energization to the solenoid 21 of the electromagnetic valve mechanism 20 is stopped, and the spool valve 22 is closed. 19 and the drain passage 23 are disconnected. Therefore, the fuel in the pressure-feeding bonzo chamber 13 has no place to escape and is therefore pressurized.

The high pressure in the pressure feeding I pump chamber 13 is transferred to the pressure receiving chamber 38 of the injection cylinder 7.
can be conveyed to. Therefore, the injection plunger 36 pressurizes the fuel in the injection pump chamber 37 at a speed increased by the pressure receiving area ratio with the pressure-feeding plunger 12.

The high-pressure fuel in the injection bomb f chamber 37 is transferred to the fuel passage 47.
is sent to the injection nozzle 50 via.

Note that the injection pump chamber 37 communicates with the metering passage 27, but at this stage, the pressure feeding plant gear 12 is lowered and the metering annular groove 35 is connected to the metering boat 2 b a +
Since the metering boats 26a and 26b are also located below the metering boat 26b, they are closed by the pressure-feeding sylanger 12, so that fuel will not flow back from the injection bonzo chamber 37 to the metering passage 25 side. .

The fuel sent to the injection nozzle 50 is transferred to the nozzle spring 5
When the pressure exceeds the valve opening pressure determined by the biasing force 2, the needle valve 5 is opened and the liquid is injected through the valve hole 53.

As the pressure-feeding plunger 12 continues to descend, the injection plunger 36 moves downward, and the spill lead 42 moves into the spill hole 3.
9 is opened, the fuel in the injection pump chamber 37 is returned to the metering passage 25 via the vertical hole 45, the horizontal hole 44, the annular groove 43, the spill hole 39, and the spill passage 40. As a result, the pressure inside the injection pump chamber 37 decreases, so the needle valve 51 of the injection nozzle 50 closes the valve hole 53, and injection ends.

The pressure-feeding plunger 12 then further descends, pushing down the injection syringer 36. When the drain lead 46 of the injection gland 36 opens the drain boat 41, the high pressure fuel in the pressure-feeding bong chamber I3 flows into the pressure receiving chamber 38, the drain, the port 41, the sub-gearry 10. The fuel is returned to the fuel tank 81 via the main gear rally 5 and the overflow passage 85. At this point, the driving of the injection silant gloss 36 is stopped.

The pressure feed planar 12 continues to descend further, and when the spill reed 28 opens the feed boat 17, the pressure feed bonnet chamber 13
The fuel is fee r,? -) It is also discharged from 17. Then, the pumping plant gear 12 continues to descend, reaches the bottom dead center, and stops.

As the cam operates, the cam follower 14 is raised by the urging force of the follower spring 15, and the pressure-feeding grunge 12 is also raised and stops at the top dead center. Thereafter, the above-mentioned operation is repeated.

By the way, the above-mentioned operation is performed at engine speed NF,
The injection pressure increases accordingly. That is, the fuel pressure in the pressure feed ponzo chamber 13 pressurized by the pressure feed granger 12 driven by the cam is low when the engine speed N8 is low, and increases as the engine speed N8 increases. . As a result, normally the injection pressure is as shown in characteristic A in Fig. 4, and when the rotation speed N6 is low, the injection pressure is also low.
Moreover, as the rotational speed N8 increases, the injection pressure also increases proportionally.

However, in this embodiment, the operation is as follows.

That is, as the pressure feed pump chamber 13 descends, the pressure within the pressure feed pump chamber 13 increases. The main lead 28 of the pressure feeding plunger 12 is connected to the feed boat 17 and the pressure receiving boat 6.
0 and the pressure-feeding Ponzo chamber 13 before closing the pressure regulating boat 61
The pressure inside is called preflow pressure, and this preflow pressure acts on the pressure regulation chamber 63 via the pressure receiving boat 6θ and the pressure regulation passage 62, and causes the nozzle spring seat 64 to move into the nozzle spring 5.
It has the effect of pushing down against 4. When the pre-flow pressure increases and the nozzle spring seat 64 is pushed down, the nozzle gelling 54 is bent to increase the opening pressure of the needle valve 5, and the rod 64m formed on the nozzle spring seat 64 moves the needle valve 5 no. to restrict the lift of the needle valve 51. In addition, the lift tit of the needle valve 51 and the valve hole 5
Figure 2 shows the relationship between the hole surface thickness of No. 3.

On the other hand, the preflow pressure acts to push down the control valve 66 via the pressure regulating boat 61. When the preflow pressure increases and pushes down the control valve 66 against the spring 67,
As the control valve 66 descends, the first waste e9,
The second (Di-door 0 is opened and then the drain boat 7) is opened. Therefore, the relationship between the downward stroke of the control valve 66 and the opening area of the boats 69, 70 and 71 is as shown in FIG.

In the timing chart shown in FIG. 4, when the engine speed N8 is less than or equal to n1, the preflow pressure is low, so the nozzle spring seat 64 is hardly pressed down, and therefore the nozzle spring 52 does not bend. The amount of downward lift of the control valve 66 is still small and each port 69,70 is closed. In this state, the main lead 28 of the pressure-feeding plunger 12 closes the feed port 12, the pressure receiving pressure yh=-trot o, and the pressure regulating port 61, and when the solenoid valve mechanism 20 is closed at a predetermined injection timing, the injection occurs as described above. The plunger 36 is driven to pressurize the metered fuel in the injection 2 pump chamber 37 and send it to the injection nozzle 50. On this occasion,
The opening pressure of the needle valve 51 is relatively low because the nozzle spring 52 is not bent, and the maximum lift of the needle valve 51 is also large because the spring seat 640 and the rod 64a are separated. Therefore, the injection pressure follows characteristic A.

When the engine speed exceeds nl, the preflow pressure gradually increases, but the control valve 66 does not open the first port 69 and the second boat 70. At this stage, the Luer 0-pressure acts on the pressure regulating chamber 63 to push down the nozzle gelling sheet 6'4 and bend the nozzle gelling 54. Therefore, the opening pressure of the needle valve 51 increases, and since the needle valve 51 is regulated by the rod 64a, the maximum amount is small and the opening area of the valve hole 53 is reduced. Therefore, as shown by characteristic B, the injection pressure increases compared to the normal case (% characteristic A), and the injection period also becomes longer. Therefore, the fuel is atomized and the combustibility at low speeds is improved. In this state, the control valve 66 is connected to the first and second ports 69.
This continues until vo is opened, and the pressure in the pressure regulating chamber 63 increases as the synflow pressure increases, thereby increasing the valve opening pressure, reducing the needle valve lift it, and increasing the injection pressure.

When the engine speed exceeds n2, the downward lift amount of the control valve 66 increases, and the annular groove 72 causes the first port 69 and the second port 70 to communicate with each other. The first eye? - Toro 9 is connected to the pressure regulating passage 62, and the second 7Jz-) 7 (7 is open to the sub gear rally 10, so the pressure regulating passage 62
pressure is released to the sub-gearry 10. That is, the pressure in the internal pressure chamber 63 is
Since the air is released to the sub-gear lary 1θ according to the opening area of It rises. Therefore, when the rotational speed is in the range from n2 to n3, the injection pressure gradually increases so as to approach the normal characteristic A.

When the engine speed is in the range from n3 to n4, the control valve 66
is lowered and the annular groove 72 fully opens the first port 69, 70, but the drain boat 71 is not yet opened, and at this stage, all the pressure in the pressure regulating chamber 63 is released, so the sub-gearry 10 is closed. (equivalent to pressure)
, the same as the normal injection pressure (characteristic A).

When the rotational speed further increases and exceeds Jn4, the synflow pressure at this time causes the control valve 66 to close the drain lead 7.
3 to open 7J. Then, some of the fuel in the pressure pump chamber 13 drains into the pressure regulating boat 61! Since the pre-flow pressure is discharged to the sub-gear 2s 10 via -' p71, the pre-flow pressure is also lower than when it is normal (as shown by the broken line). Therefore, the pressure increase required for fuel injection within the pressure-feeding ponzo chamber 13 is delayed, so that the injection pressure becomes lower than in the normal case. In other words, in a high rotation range of n or more, the injection pressure is lower than that of characteristic A, which makes it possible to improve fuel consumption, smoke, exhaust gas, noise, torque, etc.

Note that these characteristics can be freely selected and set as follows. That is, point a shown in FIG. 4 can be lower than the rotation speed n1 by expanding the pressure receiving area of the nozzle spring seat 64 facing the pressure regulating chamber 63 or by setting the opening pressure of the needle valve low. Can be set in the area. Moreover, if it is reversed, the rotational speed nl can also be set in a higher range.

Point b and point 0 can be placed on the low speed side by increasing the area receiving the press-low pressure of the control valve 66 or reducing the set load of the sgel ring 67, and vice versa.

Also, the change in pressure from point b to point 0 is determined by the first port 69.
, if the opening area of the second port 70 is made smaller, the rate of increase in pressure will increase, and conversely, if the opening area is made larger, the rate of pressure increase will be reduced, making it possible to match characteristic A at a rotation speed lower than n3. can.

Further, the point d can be shifted to the low speed 1 rule by moving the drain port 71 closer to the first port 69 and the second port 70.

In this way, the change point a-=d of each characteristic can be freely changed by selection.

Another embodiment of the present invention shown in FIG. 5 will be described. This embodiment differs from the embodiment shown in FIG. 1 in that a nozzle spring seat 201 and a lift guide 202 are constructed separately, and the lift guide 202
3 and this lift guide 20
The point is that a rod 204 is formed at 2.

According to such a configuration, the opening pressure of the needle valve 51 does not change, and since the rod 204 is lowered by receiving the preflow pressure by the lift guide 202, only the needle valve lift amount is regulated.

Further, a further modification of the present invention shown in FIG. 6 will be explained. What is different from FIG. 1 is that the metering block groove 35 of the pressure-feeding flan glosser 12 and the metering ports 25a and 25b of the pressure-feeding cylinder 6 have been abolished. This is the point where it communicates with the chamber 37.

According to this configuration, the fuel metered by the metering solenoid valve 96 (first round) passes through the metering passage 25 and passes through the check valve 3.
01 is pushed open against the spring 302 and fed into the injection pump chamber 37 via the metering port 303. As in the first embodiment, the pressurized fuel in the injection pump chamber 37 is injected from the injection nozzle 50 when the pressure-feeding granger 12 is lowered, but the fuel is injected at the end of injection when the spill reed 43 opens the spill hole 39. The fuel in the pump chamber 37 is discharged from the spill passage 40 to the metering passage 25. Since this discharged fuel is returned to the injection pump chamber 37 through the check valve 201 together with the next metered fuel, metering efficiency can be increased.

In each embodiment, the pressure receiving port 60 and the pressure regulating port 61 are opened at positions where they can be closed at the same timing as the feed port 17, but when the preflow pressure is used in a low state, the pressure receiving port 60 and the pressure regulating port 61 are opened earlier. Closed position, tsumifid yJ? -1-1y may be formed above in the drawing, and may be set in the opposite direction when used at a high preflow pressure.

Although the metering device in each of the above embodiments uses the metering solenoid valve 96, the present invention is not limited thereto, and for example, a known distribution type fuel injection pump may be used.

According to the present invention described in detail above, a part of the fuel pressurized in the pressure pump chamber is guided as back pressure that acts as resistance to opening the control valve and the injection nozzle, and the control valve is connected to the pressure pump By controlling the pressure in the chamber and changing the opening tray, the above-mentioned back pressure is adjusted and the injection pressure of the nozzle is controlled. Therefore, when the engine speed is low, the injection pressure can be relatively increased, and The injection pressure can be made relatively low when the engine speed is high. Therefore, the optimum injection pressure can be obtained depending on the engine speed, which is effective for combustion characteristics, fuel efficiency, torque, exhaust gas measures, etc.

[Brief explanation of drawings]

1 to 4 show one embodiment of the present invention, FIG. 1 is a configuration diagram showing a unit injector and a metering device, and FIG.
3 is a characteristic diagram, and FIG. 4 is a timing chart. FIGS. 5 and 6 each show another embodiment of the present invention and are sectional views of a unit injector. DESCRIPTION OF SYMBOLS 1... Unit injector, 12... Force feeding plunge i113... Force feeding pump chamber, 14... Cam follower, 36... Injection plunger, 37... Injection pump chamber, 50... Injection nozzle, 51 ...Needle valve, 52...
・Nozzle spring, 20...Solenoid valve mechanism, 6o...
・Pressure boat, 6... Pressure regulating boat, 63... Pressure regulating chamber, 64... Nozzle spring seat, 66... Control valve, 69.70... Port, 71... Drain port , 96... metering solenoid valve. Applicant's representative Patent attorney Takehiko Suzue Figure 2 Lift amount of 40 valves → Figure 3 system? Figure 4 of Futodo Hall, -

Claims (1)

[Claims] The cam, which rotates in synchronization with the engine, operates the pressure-feeding granular to pressurize the fuel in the pressure-feeding pump chamber, and the injection granular is driven by the hydraulic pressure in the pressure-feeding pump chamber to preliminarily adjust the pressure according to the engine operating conditions. The fuel in the injection pump chamber into which the injection amount of fuel has been metered and introduced is pressurized by the injection silant, and this pressurized fuel is supplied to the injection nozzle to open the injection nozzle and inject it. In the fuel injection device, a part of the fuel pressurized in the pressure pump chamber is introduced as a back pressure that regulates the opening of the control valve and the injection nozzle, and the amount of opening of the control valve is controlled by the pressure pump chamber. A fuel injection device characterized in that the injection pressure is adjusted by controlling the back pressure of the injection nozzle by controlling the pressure of the injection nozzle.