JP2828033B2 - Fuel injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for a diesel engine.

[0002]

2. Description of the Related Art As a fuel injection device used for a diesel engine, one disclosed in Japanese Patent Publication No. 7-59919 is known. The general configuration of this fuel injection device will be described with reference to FIG. 6. The fuel injection device includes a nozzle needle 50a for injecting fuel into a combustion chamber (not shown) and an injection control chamber 5 for controlling the opening and closing of the nozzle needle 50a.
0b, the fuel is automatically driven by the driving force generated by the rotation of the engine.
0, a first fuel passage 54 communicating the high pressure generation chamber of the pressure pump 52 with the injection control chamber 50b, and a branch from the first fuel passage 54. Fuel release passage 55 for releasing fuel to the low pressure side
And a first fuel passage 54 and a fuel release passage 55, which are arranged at a branch portion, communicate with the injection control chamber 50b and the fuel release passage 55 at the time of starting the fuel injection, and communicate with the injection control chamber 50b at the end of the fuel injection. It mainly comprises a three-way solenoid valve 56 communicating with the fuel passage 54, and a second fuel passage 57 communicating the pressure pump 52 with the fuel reservoir 50c of the nozzle needle 50a.

According to this fuel injection device, when the three-way solenoid valve 56 is electrically excited (ON state), the communication between the high-pressure generation chamber and the injection control chamber 50b is cut off, and the injection control chamber 50b is closed. It is communicated with the fuel release passage 55. Therefore, the fuel from the pump 52 is supplied to the second fuel passage 57.
The fuel is supplied to the fuel storage chamber 50c through the fuel cell. When the difference between the fuel pressure in the fuel storage chamber 50c and the fuel pressure in the injection control chamber 50b exceeds the force of the spring 51, the nozzle needle 50a opens to perform fuel injection.

When the preset injection period ends, the excitation of the three-way solenoid valve 56 is interrupted (OFF state), and the communication between the injection control chamber 50b and the fuel release passage 55 is cut off.
The injection control chamber 50b is connected to the pressure pump 52. Thus, high-pressure fuel flows from the pressure pump 52 through the first fuel passage 54 into the injection control chamber 50b. Eventually, when the force of the spring 51 exceeds the difference between the fuel pressure in the fuel storage chamber 50c and the fuel pressure in the injection control chamber 50b, the nozzle needle 50a is pushed down, and the injection ends.

However, the three-way solenoid valve 56 used in the above-described fuel injection device needs to use a large one in order to control the high-pressure fuel supplied from the pressure pump 52 to the automatic valve type injection nozzle 50. . Since the three-way solenoid valve 56 is generally disposed above the automatic valve type injection nozzle 50, the problem is that if the three-way solenoid valve 56 is large, the size of the fuel injection device increases, making it difficult to reduce the size of the fuel injection device. There was a point. In addition, if the three-way solenoid valve 56 is large, the arrangement position of the solenoid valve is restricted, and the degree of freedom in the layout of each member above the automatic valve type injection nozzle 50 is reduced.

Therefore, in order to reduce the size of the fuel injection device, it has been proposed to configure the fuel injection device using a two-way solenoid valve that is smaller than a three-way solenoid valve. In this fuel injection device, a fuel supply passage having a first orifice and a fuel escape passage having a second orifice are separately provided in an injection control chamber by eliminating a three-way solenoid valve 56, and a fuel escape passage is provided. Is provided with a two-way solenoid valve. According to this fuel injection device, the fuel injection is performed by controlling the opening and closing of the two-way solenoid valve to adjust the fuel pressure inside the injection control chamber. In the fuel injection device, the characteristics at the beginning of the fuel injection are determined by the cross-sectional area of the second orifice, and the characteristics at the latter stage of the fuel injection are determined by the cross-sectional area of the first orifice.

[0007]

By the way, the characteristics of the fuel injection are said to be good in that the fuel injection amount gradually increases in the early stage of the injection, and the cut of the injection is sharp at the end of the injection, particularly at the end of the injection. . In order to obtain such fuel injection characteristics, it is conceivable to reduce the cross-sectional area of the second orifice and increase the cross-sectional area of the first orifice. Is substantially symmetrical with respect to the middle of the injection, it is difficult to make the waveforms of the initial injection and the late injection different. Further, the fuel injection device has a characteristic that if the cross-sectional area of one of the orifices is increased or decreased in order to change the fuel injection characteristics, the cross-sectional area of the other orifice must also be increased or decreased similarly. It is difficult to reduce the size of the second orifice and increase the size of the first orifice. Therefore,
Improving the characteristics of the early stage of injection deteriorates the characteristics of the latter stage of injection, and conversely, improving the characteristics of the latter period of injection deteriorates the characteristics of the early stage of injection, and improving both the characteristics of the early stage of injection and the characteristics of the latter period of injection. Have difficulty.

Therefore, for example, when the cross-sectional area of the second orifice is reduced, the injection characteristics in the initial injection period and the late injection period become gentle as shown by the solid line A in FIG. With this characteristic, the initial injection amount can be reduced, but the cutoff of the injection at the end of the injection becomes poor, atomization of the fuel is hindered, and the spray droplets may become large. When the size of the spray droplets is large, there is a problem that the combustion state deteriorates, black smoke increases, and fuel efficiency also decreases. Conversely,
For example, when the cross-sectional area of the first orifice is increased, the injection characteristics in the initial injection period and the late injection period become sharper, as indicated by the broken line B in FIG. With this characteristic, the cut of the injection at the end of the injection can be sharpened, but the initial injection amount is increased, and the fuel may be rapidly burned at the initial stage of the injection. When rapid combustion of fuel occurs, there is also a problem that the combustion temperature increases and NOx increases.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and to reduce the fuel injection amount in the early stage of the injection in the fuel injection device using the two-way solenoid valve, and to perform the injection in the latter period of the injection, especially at the end of the injection. It is an object of the present invention to provide a fuel injection device that can sharpen the cut.

[0010]

According to a first aspect of the present invention, there is provided a fuel injection valve having a fuel injection nozzle for injecting fuel into a combustion chamber, and an injection control chamber for controlling opening and closing of the fuel injection nozzle, and a fuel injection valve. Supply means for supplying high-pressure fuel to the fuel cell, a fuel passage connecting the injection control chamber and the fuel supply means to each other, a first orifice provided in the fuel passage, and a bypass passage bypassing the first orifice. , Disposed in the bypass passage, closing the bypass passage at the start of fuel injection,
First valve means for opening a bypass passage at the end of fuel injection;
A return passage for discharging fuel from the injection control chamber to the low pressure side outside the injection control chamber; and a second passage provided in the return passage.
And an orifice, and a second valve means disposed in the return passage for opening the return passage at the start of fuel injection and closing the return passage at the end of fuel injection.

According to a second aspect of the present invention, in the fuel injection device according to the first aspect, the second valve means is disposed downstream of the second orifice, and the first valve means is provided in the return passage in the second position. The valve closes when the fuel pressure between the second orifice and the first valve means falls below the fuel pressure supplied from the fuel supply means, and opens when the fuel pressure approaches the fuel pressure supplied from the fuel supply means. The configuration is a switching valve.

According to a third aspect of the present invention, in the fuel injection device according to the first aspect, the position of the second valve means is upstream of the second orifice, and the first valve means and the second valve means are provided. Are integrally formed by an electromagnetic solenoid type spool valve.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration diagram of the fuel injection device.
In FIG. 1, reference numeral 1 denotes a fuel injection valve used for a diesel engine. The fuel injection valve 1 mainly includes a fuel injection nozzle 2 that injects fuel into a combustion chamber (not shown), and an injection control chamber 3 that controls opening and closing of the fuel injection nozzle 2.

A needle valve 6 for intermittently connecting the fuel reservoir 4 and the injection hole 5 is slidably stored inside the fuel injection nozzle 2. A feed hole 7 for supplying fuel to the fuel reservoir 4 is connected to the fuel reservoir 4. The end of the feed hole 7 opposite to the end connected to the fuel reservoir 4 is connected to fuel supply means described later.

Above the needle valve 6, the injection control chamber 3 is arranged. A needle valve control piston 9 that presses the upper end surface of the needle valve 6 via a flange 8 is slidably stored inside the injection control chamber 3. A spring 10 is disposed between the bottom surface of the injection control chamber 3 and the flange 8 to press the needle valve 6 to close the injection hole 5.

A fuel supply means 11 for supplying fuel to the injection control chamber 3 and the fuel reservoir 4 is connected to the injection control chamber 3 via a fuel passage 12. Further, a return passage 20 for discharging the fuel inside the injection control chamber 3 to a reserve tank (not shown) communicates with the injection control chamber 3. The fuel pressure in the reserve tank is set lower than that in the injection control chamber 3. The return passage 20 has a second orifice 21 for limiting the amount of fuel discharged from the injection control chamber 3 to the reserve tank, and a second orifice 21 that opens the return passage 20 at the start of fuel injection and closes the return passage 20 at the end of fuel injection. Two-way solenoid valve 22 as valve means
Are arranged in series from the injection control chamber 3 side.

The fuel supply means 11 includes a fuel pressurizing pump 13 for pressurizing the fuel and an accumulator 1 for storing the pressurized fuel.
4 and a pressure control solenoid valve 15 disposed between the fuel pressurizing pump 13 and the pressure accumulator 14. The pressure control solenoid valve 15 opens when the fuel pressure inside the accumulator 14 drops below a predetermined value, and supplies the fuel pressurized from the fuel pressurizing pump 13 to the accumulator 14. The fuel pressurizing pump 13 includes a plunger reciprocated by a cam driven in association with a crankshaft of an engine (not shown), and a pump chamber into which the plunger is inserted and to which a feed pump is connected. ing. The fuel supplied from the feed pump is pressurized in the pump chamber by driving the plunger and is sent to the accumulator 14 under pressure.

The fuel passage 12 is provided with a first orifice 16 for limiting the amount of fuel supplied from the fuel supply means 11 to the injection control chamber 3. The injection control chamber 3 has a first
A bypass passage 17 that bypasses the orifice 16 and communicates with the fuel passage 12 is connected. A switching valve 18 is disposed in the middle of the bypass passage 17 as first valve means for closing the bypass passage 17 at the start of fuel injection and opening the bypass passage 17 at the end of fuel injection. Here, assuming that the cross-sectional area of the first orifice 16 is D1, and the cross-sectional area of the second orifice 21 is D2, D1 and D2 satisfy D1 <
The relationship of D2 is satisfied.

The switching valve 18 is a pressure switching valve which is switched by a change in fuel pressure. As shown in FIGS. 2 (a) and 2 (b), the switching valve 18 is slidably inserted into the cylinder 25. The cylinder 25 includes a plunger 28 that divides the interior of the cylinder 25 into a first pressure chamber 26 and a second pressure chamber 27, and a spring 29 that urges the plunger 28 toward the first pressure chamber 26. .

At the center of the cylinder 25, a plunger 2
One end 17b of a bypass passage 17 that is disconnected from the first pressure chamber 26 by the position 8 is connected. First
The other end 17a of the bypass passage 17 is communicated with the pressure chamber 26. The return passage 2 is provided in the second pressure chamber 27.
A pressure passage 30 (see FIG. 1) communicating between the second orifice 21 and the two-way solenoid valve 22 is connected. When the plunger 28 is in contact with the inner wall of the first pressure chamber 26, the communication passage 28 connects the one end 17b and the other end 17a of the bypass passage 17 to each other.
a is formed.

Next, the fuel injection operation of the fuel injection device will be described. First, an initial state of the fuel injection device before fuel injection is performed will be described. Since the excitation of the two-way solenoid valve 22 is shut off, the return passage 20 is shut off, and the fuel in the injection control chamber 3, the fuel reservoir 4, the fuel passage 12, the bypass passage 17, the return passage 20, and the pressure passage 30 The pressure is equal to the fuel pressure from the fuel supply means 11. As shown in FIG. 2A, since the fuel pressures inside the first pressure chamber 26 and the second pressure chamber 27 are also equal to each other, the plunger 28
Is pressed against the inner wall of the first pressure chamber 26. Since the fuel pressures inside the injection control chamber 3 and the fuel reservoir 4 are also equal to each other, the needle valve 6 is pressed against the seat portion of the fuel reservoir 4 by the urging force of the spring 10.

When the two-way solenoid valve 22 is electrically excited by a fuel injection signal from a fuel injection control device (not shown), the return passage 20 is connected to connect the injection control chamber 3 to the reserve tank. When the two-way solenoid valve 22 is opened, the fuel in the injection control chamber 3 is discharged to the reserve tank via the second orifice 21. On the other hand, the pressure passage 30
Since the fuel in the second pressure chamber 27 is also discharged to the reserve tank, the fuel in the second pressure chamber 27 is also discharged to the reserve tank, and the fuel pressure in the second pressure chamber 27 drops rapidly. When the sum of the fuel pressure in the second pressure chamber 27 and the urging force of the spring 29 is lower than the fuel pressure in the first pressure chamber 26, the plunger 28 moves to the second pressure chamber 27 side. Start moving. Further, the fuel pressure in the second pressure chamber 27 and the spring 29
When the difference between the sum of the urging forces and the fuel pressure in the first pressure chamber 26 increases, the plunger 28 abuts against the inner wall of the second pressure chamber 27 as shown in FIG. The communication between one end 17b and the other end 17a of the bypass passage 17 is cut off.

When the bypass passage 17 is shut off, the pressure in the injection control chamber 3 gradually decreases. When the sum of the fuel pressure in the injection control chamber 3 and the urging force of the spring 10 becomes lower than the fuel pressure in the fuel reservoir 4, the needle valve 6 starts to open and gradually injects fuel into the combustion chamber. When the needle valve 6 rises by a predetermined amount, the momentum is accelerated by the fuel pressure exerted on the surface of the seat.

When the preset injection period ends, the excitation of the two-way solenoid valve 22 is interrupted, and the return passage 20 is shut off. By shutting off the return passage 20, the fuel pressure in the injection control chamber 3, the return passage 20, and the pressure passage 30 increases, and the fuel pressure in the second pressure chamber 27 also increases. When the sum of the fuel pressure in the second pressure chamber 27 and the urging force of the spring 29 exceeds the fuel pressure in the first pressure chamber 26, the plunger 28 moves to the first pressure chamber 26 side. Start moving. When the plunger 28 moves and the plunger 28 comes into contact with the inner wall of the first pressure chamber 26 as shown in FIG.
communicates with a.

Due to the communication of the bypass passage 17, the fuel pressure in the injection control chamber 3 rises sharply and the needle valve control piston 9
Press down. The needle valve 6 is pressed by the seat portion by the pressing force of the needle valve control piston 9 and the urging force of the spring 10, and the fuel injection ends.

FIG. 3 is a characteristic diagram showing the relationship between the fuel injection rate and the crank angle (time). In the drawing, a solid line C is a characteristic line according to the first embodiment, a dashed line D is a characteristic line when the cross-sectional areas of the first and second orifices are both reduced, and a dashed line E is the first and second orifices. Respectively show characteristic lines when the cross-sectional areas of both are increased. As is clear from this characteristic diagram, the fuel injection rate is low at the early stage of the injection, and the cut of the injection becomes sharp at the latter stage of the injection, particularly at the end of the injection. As a result, an increase in the combustion temperature at the beginning of combustion is suppressed, NOx is reduced, and noise due to rapid combustion can also be prevented. In addition, the occurrence of back dripping of fuel can be prevented, fuel efficiency can be improved, and black smoke can be reduced.

Next, a second embodiment is shown in FIG. 4, and this embodiment will be described. In the figure, the same members as those shown in FIG. 1 are denoted by the same reference numerals as those used in FIG. 1, and the description thereof will be omitted, and different points will be described. An electromagnetic solenoid type spool valve 40 as first valve means that closes the bypass passage 17 at the start of fuel injection and opens the bypass passage 17 at the end of fuel injection is provided in the middle of the bypass passage 17. The electromagnetic solenoid type spool valve 40 communicates with a return passage 41 for discharging fuel inside the injection control chamber 3 to a reserve tank.
The return passage 41 has a second orifice 21 for limiting the amount of fuel discharged from the injection control chamber 3 to the reserve tank.
Is arranged.

The electromagnetic solenoid type spool valve 40 has a first
In addition to the operation as the valve means, the return passage 41 is opened at the start of fuel injection, and the return passage 4 is opened at the end of fuel injection.
An operation as a second valve means for closing 1 is also performed. That is, the electromagnetic solenoid type spool valve 40 performs the operations of the first valve means and the second valve means with one electromagnetic valve. As shown in FIGS. 5A and 5B, the electromagnetic solenoid type spool valve 40 includes a cylinder 42 to which the return passage 41 and one end 17b and the other end 17a of the bypass passage 17 are connected, respectively. Is slidably inserted in the
A spool valve 43 connecting one end 17b of the bypass passage 17 to the other end 17a or the return passage 41, and a spool valve 43 interposed between the spool valve 43 and the inner wall of the cylinder 42; 17a
And an electromagnetic valve 45 that moves the spool valve 43 against the urging force of the spring 44 during fuel injection.

The spool valve is formed in a round bar shape having a plurality of stages, and the projections of the stages open and close the fuel inlet / outlet provided on the wall of the cylinder 42 to allow the fuel to flow from the other end 17 a of the bypass passage 17. It is introduced into one end 17b or from one end 17b into the return passage 41, respectively.

Next, the fuel injection operation of the fuel injection device according to the second embodiment will be described. First, a state before the fuel injection of the fuel injection device before the fuel injection is performed will be described. Since the excitation of the solenoid valve 45 is shut off, the spool valve 43
Is pressed against the inner wall. In this state, the spool valve 43
Connects the one end 17b and the other end 17a of the bypass passage 17 so that the fuel pressure in the injection control chamber 3 is substantially equal to the fuel pressure in the fuel reservoir 4, the fuel passage 12, and the bypass passage 17. Therefore, the needle valve 6 is pressed against the seat portion of the fuel reservoir 4 by the urging force of the spring 10 because the fuel pressure inside the injection control chamber 3 and the fuel reservoir 4 is substantially equal.

When the solenoid valve 45 is electrically excited by a fuel injection signal from a fuel injection control device (not shown), the spool valve 43 opposes the urging force of the spring 44, and
As shown in FIG. By the movement of the spool valve 43, one end 17b on the side of the injection control chamber 3 is connected to the return passage 41, and the fuel in the injection control chamber 3 is discharged to the reserve tank via the second orifice 21. When the fuel pressure in the injection control chamber 3 gradually decreases and the sum of the fuel pressure in the injection control chamber 3 and the urging force of the spring 10 becomes lower than the fuel pressure in the fuel reservoir 4, the needle valve 6 Begins to open and gradually injects fuel into the combustion chamber. When the needle valve 6 rises by a predetermined amount, the momentum is accelerated by the fuel pressure exerted on the surface of the seat.

When the preset injection period ends, the excitation of the solenoid valve 45 is interrupted, and the spool valve 43 is turned off as shown in FIG.
As shown in (a), the urging force of the spring 44 presses the inner wall of the cylinder 42. One end 17 of the bypass passage 17
b and the other end 17a communicate with each other, so that the injection control chamber 3
Is supplied from the fuel supply means 11, and the fuel pressure in the injection control chamber 3 rises sharply. When the fuel pressure in the injection control chamber 3 approaches the fuel pressure in the fuel reservoir 4, the needle valve 6 is pressed by the pressing force of the needle valve control piston 9 and the urging force of the spring 10.
Is pressed by the seat portion, and the fuel injection ends.

The characteristic line indicating the relationship between the fuel injection rate and the crank angle (time) of the fuel injection device of the second embodiment also shows a gradual increase in the fuel injection amount at the beginning of the injection as shown by the solid line C in FIG. However, it shows a characteristic that the cut of the injection becomes sharp at the end of the injection, particularly at the end of the injection. Then, as in the first embodiment, the fuel injection rate is low at the early stage of the injection, and the cutoff of the injection becomes sharp at the latter stage of the injection, particularly at the end of the injection. As a result, an increase in the combustion temperature at the beginning of combustion is suppressed, NOx is reduced, and noise due to rapid combustion can also be prevented. In addition, the occurrence of back dripping of fuel can be prevented, fuel efficiency can be improved, and black smoke can be reduced.

[0034]

As described above, according to the first aspect of the present invention, the injection control chamber for controlling the opening and closing of the fuel injection nozzle and the fuel supply means for supplying high-pressure fuel to the fuel injection valve are connected to each other. A bypass passage that bypasses the first orifice provided in the fuel passage, and a return passage that discharges fuel in the injection control chamber to the low-pressure side outside the injection control chamber, and opens the return passage at the start of fuel injection, Since the second valve means for closing the return passage at the end of fuel injection is provided, the injection characteristics at the beginning of injection are moderated, the injection rate at the beginning of injection is reduced, and the injection characteristics at the end of injection are sharpened. The end of the injection, particularly at the end of the injection, becomes sharper. Therefore, it is possible to achieve both a reduction in the injection rate at the beginning of the injection and a sharp running out of fuel in the latter part of the injection.
Further, the expansion of the spray droplets of the fuel at the end of the injection is prevented, the fuel efficiency can be improved, and the black smoke can be reduced. Furthermore, rapid combustion due to an increase in the initial injection amount is prevented, the combustion temperature can be suppressed, and the amount of noise and NOx generated can be reduced.

According to the second aspect of the present invention, the first valve means is a switching valve which is opened and closed by fuel pressure between the second orifice of the return passage and the first valve means. The first valve means is controlled to open and close only by a change in fuel pressure between the start of fuel injection and the end of fuel injection. Therefore, in addition to the effect of the first aspect of the present invention, the solenoid valve and the control device used for the first valve means can be omitted, and the configuration of the fuel injection device can be simplified. In addition, it is possible to reduce the size and increase the degree of freedom in layout.

According to the third aspect of the present invention, the first valve means and the second valve means are integrally formed by an electromagnetic solenoid type spool valve. The responsiveness of the valve means can be improved, and the reliability of the operation of each valve means can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a main part of a fuel injection device for a diesel engine according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of the solenoid valve of FIG. 1, wherein (a) shows an initial state of the solenoid valve and a state at the end of fuel injection;
(B) shows a state at the time of fuel injection of the solenoid valve.

FIG. 3 is a characteristic diagram showing a relationship between a fuel injection rate and a crank angle (time).

FIG. 4 is a schematic diagram of a main part of a fuel injection device for a diesel engine according to a second embodiment of the present invention.

FIG. 5 is an enlarged cross-sectional view of the solenoid valve shown in FIG. 4, wherein (a) shows an initial state of the solenoid valve and a state at the end of fuel injection;
(B) shows a state at the time of fuel injection of the solenoid valve.

FIG. 6 is a schematic view of a main part of a conventional fuel injection device for a diesel engine using a three-way solenoid valve.

FIG. 7 is a characteristic diagram showing a relationship between a fuel injection rate and a crank angle (time) of a fuel injection device using a two-way solenoid valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel injection valve 2 Fuel injection nozzle 3 Injection control chamber 11 Fuel supply means 12 Fuel passage 20, 41 Return passage 21 Second orifice 22 Two-way solenoid valve 16 First orifice 17 Bypass passage 18 Switching valve 25, 42 Cylinder 26 First pressure chamber 27 Second pressure chamber 28 Plunger 29,44 Spring 40 Electromagnetic solenoid type spool valve 43 Spool valve 45 Electromagnetic valve

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kenji Sasaki 5-33-8 Shiba, Minato-ku, Tokyo, Mitsubishi Motors Corporation (56) References JP-A-59-7768 (JP, A) 6-93936 (JP, A) JP 2-22663 (JP, U) JP 7-59919 (JP, B2) (58) Field surveyed (Int. Cl. ⁶ , DB name) F02M 47 / 00

Claims (3)

(57) [Claims] 1. A fuel injection valve having a fuel injection nozzle for injecting fuel into a combustion chamber, an injection control chamber for controlling the opening and closing of the fuel injection nozzle, and fuel supply means for supplying high-pressure fuel to the fuel injection valve A fuel passage connecting the injection control chamber and the fuel supply means to each other; a first orifice provided in the fuel passage; a bypass passage bypassing the first orifice; First valve means for closing the bypass passage at the start of fuel injection and opening the bypass passage at the end of fuel injection; and a return passage for discharging fuel from the injection control chamber to a low pressure side outside the injection control chamber. A second orifice provided in the return passage; and a second orifice disposed in the return passage, wherein the return passage is opened at the start of fuel injection, and the return A fuel injection apparatus characterized by comprising a second valve means for closing the down path, the. 2. The method according to claim 1, wherein the position of the second valve means is the second valve means.
Downstream of the orifice, wherein the first valve means is configured to reduce a fuel pressure between the second orifice and the first valve means in the return passage by a fuel pressure supplied from the fuel supply means. 2. The fuel injection device according to claim 1, wherein the switching valve is a switching valve that closes when the fuel pressure drops below a predetermined value and opens when the pressure approaches the fuel pressure supplied from the fuel supply means. 3. The method according to claim 2, wherein the position of the second valve means is the second position.
2. The fuel injection device according to claim 1, wherein the first valve means and the second valve means are integrally formed by an electromagnetic solenoid type spool valve. 3.