JPH04123335U - Initial discharge prevention mechanism of fuel injection device - Google Patents

Abstract

(57) [Summary] [Purpose] The purpose is to improve starting performance by preventing the initial discharge of fuel. [Configuration] A first passage 33 that supplies fuel from the fuel pump 1 to the first fuel pressure regulator 2 and a downstream chamber 2 of the fuel injection valve 20
A discharge prevention valve 35 is provided to alternately open and close a second passage 34 that supplies water to the second passage 34. Opening/closing switching of the discharge prevention valve 35 is controlled by the differential pressure between the manifold pressure applied to the first diaphragm chamber 36 and the fuel pressure of the fuel pump 1 applied to the second diaphragm chamber 37, and when the engine is stopped, the second passage 34 is closed. The first passage 34 is opened during operation. At startup, before the discharge prevention valve 33 switches and operates, fuel from the fuel pump 1 is filled into the downstream chamber 23 from the second passage 34 to prevent the initial discharge of fuel from the fuel injection valve 20.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention adjusts the amount of fuel injection according to intake manifold pressure and engine speed. The present invention relates to a pressure-balanced fuel injection device that controls.

0002

[Conventional technology]

As an example of this type of fuel injection device, the present applicant has disclosed Japanese Patent Application No. 2-77286 as follows. There are some suggestions.

[0003]This device will be explained with reference to FIG. 3. In the figure, 1 is a fuel pump, 2 is a first fuel pressure regulator that converts intake manifold pressure Pm into fuel pressure _P1 , and intake manifold pressure Pm is applied. The negative pressure chamber 3 and the fuel chamber 4 to which fuel is supplied from the fuel pump 1 are partitioned by a diaphragm 5 which is pressed by a spring 5a, and the fuel chamber 4 is provided with an outlet 4a for fuel return. A second fuel pressure regulator 6 is connected to the first fuel pressure regulator 2 via a fuel passage 7, and is supplied with fuel from an atmospheric pressure chamber 8 to which atmospheric pressure Po is applied and the fuel chamber 4, and maintains a constant pressure P. ₂ (<P ₁ ) and a constant pressure chamber 9 that returns fuel from an outlet 9a is partitioned off by a diaphragm 10 that is compressed by a spring 10a.

[0004] Reference numerals 12 and 13 denote a first solenoid valve and a second solenoid valve, which are sequentially arranged in the fuel passage 7 and control the opening area of the passage 7 according to the engine speed, respectively, and are connected to an electronic control unit (not shown). When the same pulse signal is input from , when this pulse signal is HIGH, the first solenoid valve 12 is closed and the second solenoid valve 13 is opened, and when it is LOW, the first solenoid valve 12 is opened and the second solenoid valve is The valve 13 is closed, and the valves 13 are opened and closed in opposite directions. Then, by controlling the opening and closing as shown in FIG. 4, the fuel pressure in the fuel passage 7 between both solenoid valves is taken out according to the engine speed as a fuel pressure _P3 corresponding to the intake manifold pressure Pm and the engine speed. It will be.

Reference numeral 14 denotes a third fuel pressure regulator that converts this fuel pressure P ₃ into an adjusted fuel pressure P ₄ (<P ₃ ), which includes a first fuel pressure chamber 15 to which the above-mentioned fuel pressure P ₃ is applied, and a fuel injection chamber to be described later. A diaphragm 17 separates a second fuel pressure chamber 16 from which a constant return flow rate is introduced from the valve and is controlled to an adjusted fuel pressure _P4 according to the fuel pressure _P3 . A spring 18 is provided to press the diaphragm 17 toward the first fuel pressure chamber 15. Therefore, the rate of change of the adjusted fuel pressure P ₄ with respect to the fuel pressure P ₃ can be reduced.

Reference numeral 20 indicates a fuel injection valve that is arranged for each cylinder and controls the amount of fuel injected into the intake manifold, and 21 indicates a fuel flow rate Q ₁ from the fuel chamber 4 of the first fuel pressure regulator 2 to the fuel injection valve 20. It is a metering jet that measures the amount of water. In the fuel injection valve 20, 22 is an upstream chamber provided with a discharge port 22a to which the fuel flow rate _Q1 is supplied from the metering jet 21 and can inject the fuel flow rate _Q2 to the intake manifold, and 23 is the upstream chamber of the third fuel pressure regulator 14. A downstream chamber communicates with the dual combustion pressure chamber 16 to deliver a constant flow rate Q ₃ and to which an adjusted fuel pressure P ₄ is applied; 24 is a diaphragm that partitions the upstream chamber 22 and the downstream chamber 23; 25 communicates the upstream chamber 22 and the downstream chamber 23; 26 is a valve that controls the opening and closing of the discharge port 22a in conjunction with the diaphragm 24, 27 is a spring that presses the diaphragm 24 in the direction of closing the valve 26, and the fuel pressure _P5 in the upstream chamber 22 is the adjusted fuel pressure. It is controlled to be balanced with the sum of the loads of P ₄ and the spring 27.

Therefore, the differential pressure (P ₅ −P ₄ ), that is, the pressure loss of the differential pressure jet 25, is controlled to be constant, and the fuel flow rate Q ₁ is equal to the sum of the fuel flow rate Q ₂ and the constant return flow rate Q ₃ .

[0008] Under the above-mentioned configuration, when the engine is operated, the intake manifold pressure P m is converted to the fuel pressure P ₁ and this is sent to the fuel passage 7 , the first and second solenoid valves 12 and 13 operate as shown in the figure. As shown in 4, the duty ratio is determined according to the engine speed, and the opening/closing is controlled. Therefore, the fuel pressure _P3 generated between the two solenoid valves 12 and 13 increases when the engine speed is low, and decreases as the engine speed increases.

[0009] By the way, the fuel flow rate required by the engine depends on the engine speed and intake mass. It is proportional to the product of the air density of the Nifold, but the air density is proportional to the pressure, that is, the pressure difference (P₁− P₂), the fuel pressure P can be changed depending on the engine speed.₁application of Adjust the ratio (duty ratio of the first and second solenoid valves 12 and 13) to obtain the fuel pressure P₃Adjust the fuel pressure P_FourBy converting the request into Adjustment fuel pressure P according to fuel flow rate_Fourcan be generated. Here, the adjusted fuel pressure P _Four increases or decreases according to the increase or decrease of intake manifold pressure Pm, and its rate of change (slope) ) decreases and increases as the engine speed increases and decreases.

[0010]In the fuel injection valve 20, the fuel pressure _P5 in the upstream chamber 22 changes as the fuel pressure _P4 in the downstream chamber 23 increases or decreases. On the other hand, since the fuel flow rate Q ₁ passing through the metering jet 21 is determined by the differential pressure across the front and rear (P ₁ - P ₅ ), the fuel flow rate Q ₁ decreases and increases as the adjusted fuel pressure P ₄ increases and decreases. Since the flow rate of No. 25 is constant at _Q3 , the fuel injection amount _Q2 (= _Q1 - _Q3 ) changes according to the adjusted fuel pressure _P4 , as shown in FIG. Therefore, the fuel injection amount Q ₂ will match the above-mentioned required fuel flow rate.

Furthermore, as shown in FIG. 6, it is possible to extract the portion of the fuel flow rate Q ₁ and the fuel injection amount Q ₂ that vary linearly with respect to the differential pressure (P ₁ -P ₅ ) of the metering jet 21. , it is possible to obtain a wide dynamic range sufficient for use in automobiles.

0012

[Problem that the idea aims to solve]

By the way, in the fuel injection system as mentioned above, if it is left unused for a long period of time after the engine has stopped, or if fuel leaks from the seat of each fuel pressure regulator 2, 6, 14. If this happens, the fuel pressure inside the system downstream of the fuel pump will drop or disappear. cormorant. In extreme cases, when the engine compartment is hot, gasoline may vaporize and enter the passageway. Vapor is generated inside the system, pushing fuel into the return passage and causing damage to the inside of the system. In some cases, fuel may run out.

When the engine is started in such a state and the engine key is turned on, the fuel supplied from the fuel pump 1 passes through the metering jet 21 and flows into the upstream chamber 22, causing the differential pressure jet 25 to flow into the upstream chamber 22. They flow to the downstream chambers 23 through them, and are filled respectively. At this time, the fuel pressure in the upstream chamber 22 rises before the fuel pressure in the downstream chamber 23, and the differential pressure between the two chambers 22 and 23 exceeds the differential pressure (P ₅ - P ₄ ) in the balanced state as described above. Therefore, the valve 26 opens against the spring load of the spring 27, and fuel is discharged from the discharge port 22a. This fuel discharge will continue until the fuel pressure of the entire system reaches a normal level. Therefore, there is a problem in that the air-fuel mixture becomes overrich upon restarting, which deteriorates starting performance.

[0014] In view of these issues, this invention suppresses the initial discharge of fuel when restarting. To provide an initial discharge prevention mechanism for a fuel injection device that improves starting performance. aimed to.

[0015]

[Means to solve the problem]

The initial discharge prevention mechanism according to the present invention prevents the fuel from the fuel pump from reaching the first fuel pressure regulation. The intake manifold is connected to the passage where the pressure is controlled by the controller and applied to the second fuel pressure regulator. There are two openings between which the fuel pressure is generated depending on the Nifold pressure and the engine speed. A mouth area setting means is provided, and this fuel pressure is printed to the first fuel pressure chamber of the third fuel pressure regulator. is converted into regulated fuel pressure in the second fuel pressure chamber, and the pressure is controlled by the first fuel pressure regulator. The fuel is supplied to the fuel injection valve via a metering jet and discharged according to the adjusted fuel pressure. and the remaining constant flow rate is returned via the second fuel pressure chamber mentioned above. In the injection device, A first passage communicating the downstream side of the fuel pump with the first fuel pressure regulator and a third fuel pressure regulator. The second passage communicating with the second fuel pressure chamber of the regulator is connected to the intake manifold pressure. A discharge prevention valve that alternately opens and closes depending on the differential pressure with the fuel pressure downstream of the fuel pump. When the engine is started, the fuel pressure on the downstream side of the fuel pump increases. It is characterized in that the first passage mentioned above is switched to be opened.

[0016] In addition, the discharge prevention valve controls the difference between the fuel pressure on the downstream side of the fuel pump and the fuel pressure of the second fuel pressure regulator. It is configured to alternately open and close the first passage and the second passage depending on the differential pressure. When the engine starts, the first passage opens due to the increase in fuel pressure on the downstream side of the fuel pump. It is characterized by being able to be switched so that it is spoken.

[0017]

[Effect]

When the engine is stopped, each fuel pressure in the system decreases and the fuel pressure downstream of the fuel pump decreases. The intake manifold pressure also decreases, while the intake manifold pressure increases to atmospheric pressure, so the difference between the two is The pressure decreases below the operating pressure of the discharge prevention valve, and the discharge prevention valve closes the first passage and closes the first passage. The two passages are held open, and when the engine is restarted next time, the combustion The fuel supplied from the fuel pump passes through the second passage to the second fuel of the third fuel pressure regulator. The initial discharge of fuel is introduced from the pressure chamber into the downstream chamber of the fuel injection valve to increase fuel pressure. When the fuel pressure on the downstream side of the fuel pump increases, the differential pressure increases to the operating pressure. The discharge prevention valve operates to close the second passage and open the first passage. This will cause fuel to be supplied to the upstream chamber, but since the fuel pressure in the downstream chamber is already high enough, Therefore, initial discharge from the fuel injection valve does not occur.

[0018] Also, when the engine is stopped, the fuel pressure of the second fuel pressure regulator and the downstream side of the fuel pump are Since the fuel pressure is equally reduced, the discharge prevention valve closes the first passage and opens the second passage. When the engine is restarted, the fuel in the fuel pump flows from the second passage to the downstream chamber. The initial discharge of fuel from the fuel injector is prevented, and the fuel pump downstream When the side fuel pressure increases and the differential pressure becomes greater than the operating pressure, the discharge prevention valve closes the second passage. The first passage is opened, but since the fuel pressure in the downstream chamber is already high enough, the fuel injection valve No initial discharge of fuel occurs.

[0019]

【Example】

Hereinafter, a first embodiment of the present invention will be explained based on FIG. The same reference numerals are used for the same parts, and the explanation thereof will be omitted. In the figure, 29 is a regulator of the fuel pump 1 and the second fuel pressure regulator 6 instead of the fuel passage 7. It is a first fuel passage that communicates with the pressure chamber 9, and there are first and second solenoid bars on the way. 12 and 13 are arranged between which the first fuel of the third fuel pressure regulator 14 is connected. The fact that it communicates with the pressure chamber 15 is the same as in the prior art described above. 30 is jet 3 The second fuel pump 1 communicates with the constant pressure chamber 9 of the second fuel pressure regulator 6 via the second fuel pressure regulator 6. The fuel passage 32 is a third fuel passage that communicates with the fuel pump 1 at one end and is separated at the other end. The first opening 33a is branched and communicates with the fuel chamber 4 of the first fuel pressure regulator 2. From the passage 33 and the second opening 34a to the second fuel pressure chamber 16 of the third fuel pressure regulator 14 A communicating second passage 34 is formed.

[0020] 35 is a discharge prevention valve that alternately opens and closes the first and second openings 33a and 34a; In this discharge prevention valve 35, 36 indicates that the intake manifold pressure Pm is applied. A first diaphragm chamber 37 is connected to a third diaphragm chamber 37 through the first passage 33 and the first opening 33a. A second diaphragm chamber 38 communicates with the fuel passage 32. 7 and the third fuel passage 32, and 39 are the first and second diaphragms. A diaphragm 40 partitions the chambers 36 and 37, and the diaphragm 40 A valve element 41 is a diaphragm 39 that alternately opens and closes the first and second openings 33a and 34a. The valve body 40 is a spring that presses the first opening 33a in a direction that closes the first opening 33a. or , 42 are jets arranged in the second passage 34.

The discharge prevention valve 35 opens the first passage 33 and closes the second passage 34 when the engine is running, and closes the first passage and keeps the second passage open when the engine is stopped. controlled to do so. For this reason, assuming that the fuel pressure in each passage on the downstream side of the fuel pump 1 is P ₆ , when the discharge prevention valve 35 opens the first opening 33 a during engine operation, the control fuel pressure P ₁ of the first fuel pressure regulator 2 and P ₆ will be controlled to the same size. Therefore, in the first fuel passage 29, the fuel pressure _P3 can be generated between the first and second solenoid valves 12 and 13, as in the prior art.

Further, the operating pressure Px for switching the opening and closing of the discharge prevention valve 35 is such that the first diaphragm chamber 36 is at atmospheric pressure, and the second diaphragm chamber 37 is at a predetermined value smaller than the control fuel pressure P ₂ of the second fuel pressure regulator 6. It is set to be the differential pressure when . Moreover, by applying the intake manifold pressure as back pressure to the discharge prevention valve 35, the discharge prevention valve 35 can be activated even when the intake manifold pressure is high and the fuel pressure _P1 is low, such as in a no-load state during engine operation. A sufficient differential pressure exceeding the pressure Px can be ensured.

Since this embodiment is configured as described above, when the engine stops, the fuel pump 1 stops and each fuel pressure in the system decreases, and the fuel pressure P in the fuel chamber 4 of the first fuel pressure regulator 2 decreases. ₁ also decreases from the control fuel pressure. On the other hand, since the intake manifold pressure Pm rises to atmospheric pressure, the differential pressure applied to the diaphragm 39 of the discharge prevention valve 35 becomes smaller, and when it becomes lower than the operating pressure Px, the diaphragm 39 is displaced toward the second diaphragm chamber 37. Then, the valve body 40 opens the second opening 34a, and seats on the seat portion of the first opening 33a to close it.

Next, at the time of restart, the fuel pump 1 is operated and the fuel supplied is introduced from the third fuel passage 32 to the second fuel pressure chamber 16 of the third fuel pressure regulator 14 via the second passage 34, Furthermore, it is filled into the downstream chamber 23 and raises the fuel pressure _P4 . On the other hand, since the passage from the fuel pump 1 to the upstream chamber 22 is blocked, the differential pressure between the downstream chamber 23 and the upstream chamber 22 becomes larger than the differential pressure (P ₅ - P ₄ ) in the balanced state during operation, and the fuel No initial discharge of fuel from the injection valve 20 occurs.

At the same time, the fuel pressure P ₆ on the downstream side of the fuel pump 1 begins to rise, and this is applied to the second diaphragm chamber 37 from the third fuel passage 32 via the jet 38 with a delay, and the fuel pressure in this chamber 37 also increases. begins to rise. When the differential pressure with the first diaphragm chamber 36 exceeds the working pressure Px, the diaphragm 39 is displaced toward the first diaphragm chamber 36, and the valve body 40 is also moved, so that the first opening 33a opens and the second opening 33a opens. Opening 34a is closed.

For this purpose, fuel from the fuel pump 1 now flows via the first passage 33 into the upstream chamber 22 via the fuel chamber 4 of the first fuel pressure regulator 2 and each metering jet 21 . As a result, the fuel pressure P ₆ on the downstream side of the fuel pump 1 and the controlled fuel pressure P ₁ of the first fuel pressure regulator 2 are controlled to the same magnitude, resulting in a normal controlled pressure state similar to the above-mentioned prior art. Furthermore, at this point, the fuel pressure P ₄ in the downstream chamber 23 has already risen to the set pressure for maintaining a balanced state, and the subsequent flow of fuel into the upstream chamber 22 causes the initial discharge of fuel from the discharge port 22a to decrease. Does not occur. Regarding the fuel injection valve 20, the product of the effective area of the diaphragm 24 and the vertical differential pressure ( _P5 - _P4 ) of the diaphragm 24 is the opening force _N1 of the valve 26, and this force _N1 is the closing force of the spring 27. When it becomes greater than N ₂ , the valve 26 opens and fuel discharge occurs.

[0027] As described above, according to this embodiment, the initial discharge of fuel at the time of restart can be prevented, and the engine can be restarted. Ranking time can be shortened and startability can be improved.

[0028] Next, a second embodiment of the present invention will be described based on FIG. In the discharge prevention valve 44 in this embodiment, the first diaphragm chamber 45 has a jet 46 The second diaphragm chamber 47 communicates with the fuel pump 1 through the fourth fuel passage 48. It communicates with the constant pressure chamber 9 of the second fuel pressure regulator 6 via the fuel pressure regulator 6 . Also, both diaphragms A valve body 50 interlocking with a diaphragm 49 that partitions the chambers 45 and 47 is connected to the diaphragm 4 9, the first opening 33a of the first passage 33 and the second opening 3 of the second passage 34 4a are controlled to open and close alternately. The first port on the downstream side of the first opening 33a A rod-shaped portion of the valve body 50 is provided in a communication path between the passage 33 and the second diaphragm chamber 47 in a fluid-tight manner. Since the first passage 33 is slidably inserted into the second diaphragm chamber, the fuel in the first passage 33 is transferred to the second diaphragm chamber. No flow into 47. The diaphragm 49 is connected to the valve body 50 by the spring 54. The first diaphragm chamber 45 is pressed in the direction that closes the first opening 33a. Ru.

[0029] Then, the discharge prevention valve 44 opens the first passage 33 when the engine is operating, and the discharge prevention valve 44 opens the first passage 33 during engine operation. Similarly to the first embodiment, the second passage 34 is opened when the vehicle is stopped.

[0030] Further, the operating pressure Px' for switching the opening and closing of the discharge prevention valve 44 is equal to the fuel pressure P when the engine is operating. ₁ and P₂is set to have a predetermined magnitude smaller than the differential pressure of Furthermore, en In low load conditions such as during engine operation, the fuel pressure P₁becomes smaller, so the differential pressure (P₁-P₂) may be a small value close to the operating pressure Px', so the differential pressure of the discharge prevention valve 44 In order to improve the detection accuracy, the diameter of the diaphragm 49 is set to a certain degree large. There is a need.

[0031] Further, in this embodiment, the second fuel passage 30 and jet 31 of the first embodiment are not provided. Not yet. In addition, as shown by the broken line in FIG. 2, the first diaphragm chamber 45 and the fourth fuel A communication passage 52 communicating with the passage 48 via a jet 51 is provided to remove vapor. You may also do this.

[0032] Since this embodiment is configured as described above, the discharge can be prevented even when the engine is stopped. The fuel pressures in both diaphragm chambers 45 and 47 of the valve 44 are both reduced and equal; therefore, , the valve body 50 closes the first opening 33a and opens the second opening by the elasticity of the spring 54. 34a is kept open.

When the engine is restarted, the fuel supplied from the fuel pump 1 flows from the third fuel passage 32 to the downstream chamber 23 of the fuel injection valve 20 via the second passage 34 . At this time, since fuel does not flow into the upstream chamber 22 from the direction of the first fuel pressure regulator 2, the fuel pressure in the downstream chamber 23 increases significantly and initial discharge of fuel from the fuel injection valve 20 is prevented. At the same time, the fuel in the fuel pump 1 flows into the first diaphragm chamber 45 through the jet ₄₆ with a delay and is filled. The differential pressure between the fuel pressure and the fuel pressure in the second diaphragm chamber 47 increases and exceeds the operating pressure Px', and the discharge prevention valve 44 is switched to operate. As a result, the second opening 34a is closed and the first opening 33a is opened at the same time, so that the fuel in the fuel pump 1 passes through the first passage 33 to the fuel chamber 4 and upstream chamber 22 of the first fuel pressure regulator 2. Inflow. As a result, the fuel pressure P ₆ is controlled to the same level as P ₁ , resulting in a normal control pressure state. Furthermore, at this point, the fuel pressure _P4 in the downstream chamber 23 has already risen to the set pressure for achieving a balanced state, and the subsequent rise in fuel pressure in the upstream chamber 22 causes the differential pressure between the two chambers to exceed the balanced state. It will never become. Therefore, initial discharge of fuel does not occur at startup.

[0034] Also, when the engine is stopped, each fuel pressure in the system decreases, causing both diaphragm chambers to When the differential pressure between 45 and 47 becomes smaller than the operating pressure Px', the discharge prevention valve 44 is activated. The first opening 33a is closed and the second opening 34a is opened.

[0035] Note that the first and second solenoid valves 12 and 13 constitute opening area setting means, respectively. However, this opening area setting means is not limited to solenoid valves; The opening area may be electrically adjusted to increase or decrease using a step motor or the like.

[0036]

[Effect of the idea]

As mentioned above, the initial discharge prevention mechanism of the fuel injection device according to the present invention The downstream fuel pressure and the intake manifold pressure or the fuel pressure of the second fuel pressure regulator Equipped with a discharge prevention valve that switches and operates depending on the differential pressure of the engine. It prevents the initial discharge of fuel during subsequent restarts and reduces cranking time. Startability can be improved.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of a fuel injection device showing a first embodiment of the present invention.

FIG. 2 is a schematic explanatory diagram of a fuel injection device showing a second embodiment of the present invention.

FIG. 3 is a schematic illustration of a fuel injection device according to the prior art.

FIG. 4 is a diagram showing the period of a pulse signal depending on the engine rotation speed.

FIG. 5 is a diagram showing the relationship between intake manifold pressure Pm, engine speed, and adjusted fuel pressure _P4 .

FIG. 6 is a diagram showing the relationship between differential pressure (P ₁ -P ₅ ) and each fuel flow rate.

[Explanation of symbols]

1 Fuel pump 2 First fuel pressure regulator 6 Second fuel pressure regulator 7 Fuel passage 12 First solenoid valve 13 Second solenoid valve 14 Third fuel pressure regulator 20 Fuel injection valve 22 Upstream room 23 Downstream room 33 First aisle 34 Second aisle 35, 44 Discharge prevention valve 36,45 First diaphragm chamber 37, 47 Second diaphragm chamber

Claims (2)

[Scope of utility model registration request] Claim 1: A passage through which fuel from a fuel pump is pressure-controlled by a first fuel pressure regulator and applied to a second fuel pressure regulator, and two openings are provided between which fuel pressure is generated depending on the intake manifold pressure and the engine speed. An area setting means is provided, the fuel pressure is converted into a regulated fuel pressure by a third fuel pressure regulator, and the fuel whose pressure is controlled by the first fuel pressure regulator is supplied to the fuel injection valve via a metering jet and discharged according to the regulated fuel pressure. In the fuel injection device, the remaining constant flow rate is returned via a third fuel pressure regulator, the first passage communicating with the first fuel pressure regulator and the third fuel pressure regulator. The two passages are controlled by the differential pressure between the intake manifold pressure and the fuel pressure downstream of the fuel pump.
An initial discharge prevention mechanism, comprising a discharge prevention valve that alternately opens and closes, and is switched so that the first passage is opened due to an increase in fuel pressure on the downstream side of the fuel pump when the engine is started. 2. Two openings in a passage through which fuel from the fuel pump is pressure-controlled by a first fuel pressure regulator and applied to a second fuel pressure regulator, between which fuel pressure is generated depending on the intake manifold pressure and the engine speed. An area setting means is provided, the fuel pressure is converted into a regulated fuel pressure by a third fuel pressure regulator, and the fuel whose pressure is controlled by the first fuel pressure regulator is supplied to the fuel injection valve via a metering jet and discharged according to the regulated fuel pressure. In the fuel injection device, the remaining constant flow rate is returned via a third fuel pressure regulator, the first passage communicating with the first fuel pressure regulator and the third fuel pressure regulator. The two passages are connected by the differential pressure between the fuel pressure downstream of the fuel pump and the fuel pressure of the second fuel pressure regulator.
An initial discharge prevention mechanism, comprising a discharge prevention valve that alternately opens and closes, and is switched so that the first passage is opened due to an increase in fuel pressure on the downstream side of the fuel pump when the engine is started.