JP2006170153A - Fuel injection device and fuel injection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection device 1 and a fuel injection method capable of increasing injection pressure without adopting a complicated structure. <P>SOLUTION: The fuel injection device 1 is provided with a fuel injection valve 2 injecting and supplying fuel accumulated in a common rail 4 to an engine, and a fuel shut off valve 3 built in a high pressure supply flow passage A for leading fuel to an injection hole form the common rail 4 and closing the high pressure supply flow passage A and opening the high pressure supply flow passage A if needed. Consequently, pressure pulsation can be generated by temporarily opening the fuel shut off valve 3 and temporarily introducing fuel to the high pressure supply passage A in a downstream side of the fuel shut off valve 3. Fuel pressure can be increased in the high pressure supply flow passage A by this pressure pulsation. Consequently, injection pressure can be increased by a simple structure having a fuel shut off valve 3 built in the high pressure supply flow passage A. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel injection device and a fuel injection method for injecting and supplying fuel to an engine.

[Conventional technology]
In recent years, the pressure (injection pressure) of fuel injected into an engine has become higher and higher in response to demands such as fuel efficiency reduction, higher output, and black smoke reduction in the engine. In response to such high injection pressure, for example, in a direct injection type engine such as a diesel engine, a common rail type fuel injection device capable of accumulating fuel in a high pressure state has been considered and put into practical use. Further, a fuel injection device that boosts the fuel accumulated in the common rail and supplies it to the injection nozzle is also considered.

  As described above, as a pressure increasing means for further increasing the pressure of fuel to be injected, for example, a pressure increasing piston provided with a pressure receiving surface having a predetermined area and a pressure surface having an area smaller than the pressure receiving surface is used. Is known (see, for example, Patent Document 1). According to this pressure increasing means, the pressure of the fuel is increased by causing the pressure of the fuel of the common rail to act on the pressure receiving surface and pressurizing the fuel with the pressing surface having a smaller area than the pressure receiving surface.

[Problems with conventional technology]
However, in the fuel injection device using this pressure increasing means, in addition to the existing fuel injection valve and the like, a storage chamber for storing a pressure increasing piston, a restoring spring, etc., a pressure chamber for receiving pressurized fuel, and a pressurized fuel It is necessary to provide a pressurized chamber for receiving the gas, a flow path for connecting each chamber to the common rail, the injection nozzle, and the like, and to arrange various valves and throttles. For this reason, the structure of the fuel injection device becomes extremely complicated.
Japanese Patent No. 2885076

  The present invention has been made to solve the above-described problems, and provides a fuel injection device and a fuel injection method capable of increasing the injection pressure without adopting a complicated structure.

[Means of Claim 1]
According to a first aspect of the present invention, there is provided a fuel injection device comprising: a nozzle for injecting fuel by opening and closing of an injection hole by movement of a valve element; a back pressure chamber on the side opposite to the injection hole of the valve element; A fuel injection valve having an actuator that drives the valve body under control to supply fuel supplied from a predetermined fuel supply source to the engine, and a high-pressure supply passage for guiding the fuel from the fuel supply source to the injection hole And a fuel cutoff valve that closes the high-pressure supply flow path and opens the high-pressure supply flow path as necessary. The fuel cutoff valve is a two-way valve that switches between a valve open state in which the fuel supply source and the high pressure supply flow path are in communication and a valve closed state in which the fuel supply source and the high pressure supply flow path are blocked. Then, the fuel shut-off valve is temporarily opened, pressure pulsation is generated by temporarily guiding the fuel from the fuel supply source to the downstream side of the fuel shut-off valve, and the fuel shut-off valve is led downstream of the fuel shut-off valve. When the fuel pressure is increased by pressure pulsation, the nozzle hole is opened.
Thus, the injection pressure can be increased by a simple structure in which the fuel cutoff valve is incorporated in the high-pressure supply channel.
The back pressure chamber is formed in the nozzle on the side opposite to the injection hole of the valve body. The actuator opens and closes a back pressure discharge channel for discharging fuel from the back pressure chamber to control the back pressure and drive the valve body.

[Means of claim 2]
In the fuel injection device according to the second aspect, the high-pressure discharge channel for discharging the fuel in the high-pressure supply channel branches from the high-pressure supply channel.
When the pressure of the fuel is increased by pressure pulsation, the flow path through which the fuel is temporarily guided, that is, the flow path that generates pressure pulsation is preferably as low as possible. Therefore, as described above, if the high-pressure discharge channel for discharging the fuel is branched from the high-pressure supply channel that is a channel for generating pressure pulsation, the high-pressure supply channel can be set to a low pressure.

[Means of claim 3]
The high-pressure discharge flow path of the fuel injection device according to claim 3 is provided with a discharge regulating means for regulating fuel discharge.
Thereby, when using a high-pressure supply channel for the original purpose, such as injecting fuel from a nozzle, the influence of discharge of fuel from a high-pressure discharge channel can be reduced.

[Means of claim 4]
The discharge restricting means of the fuel injection device according to claim 4 restricts the discharge flow rate by a throttle provided in the high pressure discharge flow path.
This means is one form of the discharge regulating means.

[Means of claim 5]
A check valve that opens when a pressure higher than atmospheric pressure is applied is incorporated in the high-pressure discharge passage of the fuel injection device according to claim 5.
Thereby, the valve opening pressure of the check valve can be selected from an arbitrary pressure value higher than the atmospheric pressure in accordance with the target value for increasing the injection pressure due to pressure pulsation. Here, the lower the pressure in the high-pressure supply channel before the fuel is guided, the higher the injection pressure after pressure increase due to pressure pulsation. For this reason, the valve opening pressure of the check valve is preferably as low as possible. According to the above configuration, for example, if the valve opening pressure of the check valve is set to be slightly higher than the atmospheric pressure, the injection pressure after pressure increase due to pressure pulsation can be increased.

[Means of claim 6]
The fuel shut-off valve of the fuel injection device according to claim 6 includes a nozzle that injects fuel by opening and closing the nozzle hole by movement of the valve body, and a back pressure chamber on the side opposite to the nozzle hole of the valve body. A fuel injection valve that injects fuel supplied from a predetermined fuel supply source to the engine, and guides the fuel from the fuel supply source to the injection hole. And a fuel cutoff valve that closes the high-pressure supply channel and opens the high-pressure supply channel as necessary. The fuel shut-off valve is a closed valve in which the open state in which the fuel supply source and the high pressure supply flow path communicate with each other and the high pressure supply flow path and the high pressure discharge flow path for discharging the fuel in the high pressure supply flow path communicate with each other. It is a three-way valve that switches between states. Then, the fuel shut-off valve is temporarily opened, pressure pulsation is generated by temporarily guiding the fuel from the fuel supply source to the downstream side of the fuel shut-off valve, and the fuel shut-off valve is led downstream of the fuel shut-off valve. When the fuel pressure is increased by pressure pulsation, the nozzle hole is opened.
As a result, the high pressure supply flow path can be reliably reduced to a low pressure by switching the three-way valve from the open state to the closed state after the injection is completed.

[Means of Claim 7]
In the fuel injection device according to the seventh aspect, the back pressure supply passage for supplying fuel to the back pressure chamber is branched from the high pressure supply passage.

[Means of Claim 8]
In the fuel injection device according to the eighth aspect, the check valve for preventing the back flow of the fuel from the back pressure chamber to the high pressure supply passage is incorporated in the back pressure supply passage.
When the nozzle hole is closed, the closing biasing force that biases the valve element in the closing direction is stronger than the opening biasing force that biases the valve element in the opening direction. When the opening urging force becomes stronger than the closing urging force, the valve body moves in the opening direction to open the nozzle hole. In response to such operation of the valve body, the urging force due to the fuel pressure (back pressure) in the back pressure chamber forms a closed hole urging force. For this reason, if the fuel flows out from the back pressure chamber during the time period when the injection should be stopped, the balance of the urging force in the valve body is lost and unintended injection is performed. Therefore, as described above, unintentional injection can be reliably prevented by incorporating a check valve for preventing the backflow of fuel from the back pressure chamber to the high pressure supply channel in the back pressure supply channel.

[Means of Claim 9]
In the fuel injection device according to claim 9, the back pressure supply passage for supplying fuel to the back pressure chamber is directly connected to the back pressure chamber from the fuel supply source separately from the high pressure supply passage. .
Thereby, the fuel can be supplied to the back pressure chamber without going through the high pressure supply flow path for guiding the fuel injected from the injection hole. For this reason, it is not necessary to supply a part of the fuel to be injected to the back pressure chamber, so that an unintended drop in the injection pressure can be prevented.

[Means of Claim 10]
In the fuel injection device according to the tenth aspect, the fuel injected from the injection hole is supplied to the nozzle from the high-pressure supply channel so as to exert pressure on the valve body in the direction of opening the injection hole. Further, the effective pressure receiving area of the fuel pressure acting in the direction of opening the nozzle hole with respect to the valve body is smaller than the effective pressure receiving area of the back pressure.
The injection pressure is increased by a pressure pulsation to a pressure higher than the fuel pressure upstream of the fuel cutoff valve. Therefore, when the fuel in the back pressure chamber is supplied from the fuel supply source through a flow path different from the high pressure supply flow path, the back pressure acting in the closing direction is lower than the injection pressure acting in the opening direction. There is a risk of becoming. Therefore, as described above, the effective pressure receiving area of the injection pressure acting on the valve body in the opening direction is made smaller than the effective pressure receiving area of the back pressure acting on the valve body in the closing direction. As a result, the closing biasing force due to the back pressure can be made stronger than the opening biasing force due to the injection pressure. Therefore, even if the back pressure is lower than the injection pressure, the valve body is reliably biased in the closing direction. The nozzle hole can be closed.

[Means of Claim 11]
The fuel supply source of the fuel injection device according to claim 11 has a fuel injection pump that discharges the fuel at a high pressure, a common rail that accumulates the fuel discharged from the fuel injection pump at a predetermined pressure, and a fuel cutoff valve Is mounted on the common rail.
In the high-pressure supply channel, the injection pressure after pressure increase due to pressure pulsation can be increased as the fuel cutoff valve is incorporated further upstream. Therefore, the fuel cutoff valve is mounted on the common rail as described above, and the fuel cutoff valve is incorporated in the vicinity of the common rail corresponding to the uppermost stream of the high-pressure supply flow path. Thereby, the injection pressure after pressure increase due to pressure pulsation can be increased.

[Means of Claim 12]
A fuel injection method according to a twelfth aspect of the present invention includes a nozzle that opens and closes an injection hole by movement of a valve body to inject fuel, a back pressure chamber on the side opposite to the injection hole of the valve body, and a back pressure in the back pressure chamber is reduced. A fuel injection valve having an actuator that drives the valve body under control to supply fuel supplied from a predetermined fuel supply source to the engine, and a high-pressure supply passage for guiding the fuel from the fuel supply source to the injection hole And a fuel injection device including a fuel cutoff valve that closes the high-pressure supply flow path and opens the high-pressure supply flow path as necessary. Then, the fuel shut-off valve is temporarily opened, pressure pulsation is generated by temporarily guiding the fuel from the fuel supply source to the downstream side of the fuel shut-off valve, and the fuel shut-off valve is led downstream of the fuel shut-off valve. When the fuel pressure increases due to pressure pulsation, the nozzle hole is opened, and after a predetermined time has elapsed, the actuator is deactivated and the nozzle hole is closed by the valve body, and then the fuel shut-off valve is temporarily opened again. Then, the fuel whose pressure is increased by the pressure pulsation is guided upstream of the fuel cutoff valve.
As a result, after the injection is completed, the increased pressure fuel can be recovered in the fuel supply source to suppress energy loss, and the pressure of the fuel in the high pressure supply flow path after the injection can be reduced.

  The fuel injection device of the best mode 1 includes a nozzle that injects fuel by opening and closing an injection hole by movement of a valve body, and a back pressure chamber on the side opposite to the injection hole of the valve body to control the back pressure of the back pressure chamber. A fuel injection valve that injects fuel supplied from a predetermined fuel supply source to the engine, and a high-pressure supply passage that guides the fuel from the fuel supply source to the injection hole. A fuel shut-off valve that is incorporated and closes the high-pressure supply flow path and opens the high-pressure supply flow path as necessary.

  The fuel cutoff valve is a two-way valve that switches between a valve open state in which the fuel supply source and the high pressure supply flow path are in communication and a valve closed state in which the fuel supply source and the high pressure supply flow path are blocked. Then, the fuel shut-off valve is temporarily opened, pressure pulsation is generated by temporarily guiding the fuel from the fuel supply source to the downstream side of the fuel shut-off valve, and the fuel shut-off valve is led downstream of the fuel shut-off valve. When the fuel pressure is increased by pressure pulsation, the nozzle hole is opened.

  In the fuel injection device, a high-pressure discharge channel for discharging fuel in the high-pressure supply channel branches from the high-pressure supply channel. The high-pressure discharge flow path is provided with discharge restriction means for restricting fuel discharge. The discharge regulating means regulates the discharge flow rate by a throttle provided in the high pressure discharge flow path. In addition, the high-pressure discharge passage incorporates a check valve that opens when a pressure higher than atmospheric pressure is applied.

  In the fuel injection device, a back pressure supply passage for supplying fuel to the back pressure chamber branches from the high pressure supply passage. The back pressure supply channel incorporates a check valve that prevents back flow of fuel from the back pressure chamber to the high pressure supply channel.

  The fuel supply source has a fuel injection pump that discharges fuel at a high pressure, a common rail that accumulates fuel discharged from the fuel injection pump at a predetermined pressure, and a fuel cutoff valve is mounted on the common rail.

  The fuel cut-off valve of the fuel injection device of the best mode 2 includes a valve open state in which the fuel supply source and the high pressure supply passage communicate, and a high pressure discharge flow for discharging fuel in the high pressure supply passage and the high pressure supply passage. This is a three-way valve that switches between a closed state in which the road communicates.

  The fuel supply source has a fuel injection pump that discharges the fuel at a high pressure, a common rail that accumulates the fuel discharged from the fuel injection pump at a predetermined pressure, and the fuel cutoff valve is attached to the common rail.

  The fuel cutoff valve of the fuel injection device according to the best mode 3 switches between a valve open state in which the fuel supply source and the high pressure supply passage are communicated and a valve closed state in which the fuel supply source and the high pressure supply passage are shut off. It is a two-way valve. Then, the fuel shut-off valve is temporarily opened, pressure pulsation is generated by temporarily leading the fuel from the fuel supply source to the downstream side of the fuel shut-off valve, and the fuel shut-off valve is led downstream of the fuel shut-off valve. When the fuel pressure is increased by pressure pulsation, the nozzle hole is opened.

  In the fuel injection device, a high-pressure discharge channel for discharging fuel in the high-pressure supply channel branches from the high-pressure supply channel. The high-pressure discharge flow path is provided with discharge restriction means for restricting fuel discharge. The discharge regulating means regulates the discharge flow rate by a throttle provided in the high pressure discharge flow path. In addition, the high-pressure discharge passage incorporates a check valve that opens when a pressure higher than atmospheric pressure is applied.

  In the fuel injection device, a back pressure supply passage for supplying fuel to the back pressure chamber is directly connected to the back pressure chamber from a fuel supply source separately from the high pressure supply passage.

  In the fuel injection device, the fuel injected from the injection hole is supplied to the nozzle from the high-pressure supply channel so as to exert pressure on the valve body in the direction of opening the injection hole. Further, the effective pressure receiving area of the fuel pressure acting in the direction of opening the nozzle hole with respect to the valve body is smaller than the effective pressure receiving area of the back pressure.

  The fuel supply source has a fuel injection pump that discharges the fuel at a high pressure, a common rail that accumulates the fuel discharged from the fuel injection pump at a predetermined pressure, and the fuel cutoff valve is attached to the common rail.

  In the fuel injection method using the fuel injection device according to the best mode 3, the fuel cutoff valve is temporarily opened, and fuel is temporarily led from the fuel supply source to the downstream side of the fuel cutoff valve to generate pressure pulsation. When the pressure of the fuel guided downstream from the fuel shutoff valve is increased by pressure pulsation, the nozzle hole is opened. After a predetermined time has elapsed, the actuator is deactivated and the nozzle hole is closed by the valve body. Then, the fuel shut-off valve is temporarily opened again, and the fuel increased in pressure pulsation is upstream of the fuel shut-off valve. Lead to the side.

[Configuration of Example 1]
The configuration of the fuel injection device 1 according to the first embodiment will be described with reference to FIGS. 1 to 3.
The fuel injection device 1 is a common rail type capable of accumulating fuel in a high pressure state. For example, the fuel injection device 1 injects and supplies fuel to a direct injection type engine (not shown: hereinafter referred to as an engine) such as a diesel engine. is there.

  As shown in FIG. 1, the fuel injection device 1 injects fuel supplied from a predetermined fuel supply source into the engine, and shuts off fuel supply from the fuel supply source to the fuel injection valve 2. In addition, a fuel shut-off valve 3 is provided that opens as necessary to enable fuel supply from the fuel supply source to the fuel injection valve 2.

  Here, the predetermined fuel supply source is a fuel injection pump (not shown) that discharges the fuel in a fuel tank (not shown) at a high pressure, and accumulates the fuel discharged from the fuel injection pump at a predetermined pressure. The common rail 4 to be used. The operations of the fuel injection valve 2, the fuel cutoff valve 3, the fuel injection pump, and the like are electronically controlled by commands from an ECU (not shown).

  As shown in FIG. 1 or FIG. 2, the fuel injection valve 2 includes a nozzle 7 that injects fuel by opening and closing the injection hole 6 by the movement of the valve body 5, and a direction in which the injection hole 6 is opened (opening direction). And an injection control valve 8 as an actuator for driving the valve body 5 in a direction (closing direction) for closing the injection hole 6. The nozzle 7 is connected to the lower side of the main body 12 of the fuel injection valve 2, and the injection control valve 8 is connected to the upper side of the main body 12, and are fastened and fixed by retaining nuts 13 and 14, respectively. The fuel injection valve 2 is connected to a high pressure pipe 15 for supplying fuel from the common rail 4 to the fuel injection valve 2 and a low pressure pipe 16 opened to the atmosphere to reduce the internal pressure.

  The nozzle 7 has a reservoir 19 that receives supply of fuel injected from the injection hole 6 and a back pressure that receives supply of fuel that exerts pressure on the valve body 5 in the direction of closing the injection hole 6 (closed hole direction). A chamber 20 is formed. A seat surface 21 on which the valve body 5 is seated is provided below the pool portion 19, and the nozzle hole 6 is opened in the seat surface 21. The fuel in the pool portion 19 exerts pressure on the valve body 5 in the opening direction. The back pressure chamber 20 is formed on the side opposite to the injection hole of the valve body 5. And the back pressure chamber 20 is closed by the valve body 5 at the bottom, and its volume can be expanded and contracted. The back pressure chamber 20 accommodates a spring 22 that constantly urges the valve body 5 in the closing direction.

  The injection control valve 8 is supplied with electric power from an in-vehicle power supply (not shown) in response to a command from the ECU, a solenoid 23 that generates a magnetic attractive force, a valve body 24 that is attracted and displaced by the magnetic attractive force, and a valve body 24. Is composed of a return spring 25 that urges the magnetic force in the direction opposite to the magnetic attractive force, a body 27, and the like. The body 27 is provided with a valve chamber 28 that is opened and closed by the valve body 24, a valve chamber 28, and a flow path 29 that opens to the outside of the body 27.

  When the solenoid 23 is energized and the magnetic attractive force is increased, the valve body 24 is attracted to open the upstream side of the valve chamber 28. When the energization of the solenoid 23 is stopped and the magnetic attractive force is weakened, the valve body 24 is urged by the return spring 25 to close the upstream side of the valve chamber 28.

  Further, the nozzle 7 and the main body 12 include a flow path a that connects the high-pressure pipe 15 and the reservoir 19, a flow path b that branches from the flow path a and communicates with the back pressure chamber 20, the back pressure chamber 20, and the injection control valve 8. A flow path c connecting the valve chamber 28, a flow path d connecting the flow path 29 of the injection control valve 8 and the low pressure pipe 16, and a flow path e branched from the flow path a and connected to the flow path d. It has been.

  The flow path a and the high pressure pipe 15 form a high pressure supply flow path A for guiding fuel from the common rail 4 to the nozzle hole 6.

  The flow path b forms a back pressure supply flow path B for supplying fuel to the back pressure chamber 20. The flow path b is provided with a throttle 34 for restricting the flow rate of fuel supplied to the back pressure chamber 20 and a check valve 35 for preventing back flow of fuel from the back pressure chamber 20. The check valve 35 includes a valve member 36 that opens and closes the flow path b, and a spring 37 that biases the valve member 36 in a direction to close the flow path b.

  The flow paths c and d form a back pressure discharge flow path C for discharging fuel from the back pressure chamber 20 together with the low pressure pipe 16, and are opened and closed by the injection control valve 8. The flow path c is provided with a throttle 38 for regulating the flow rate of fuel discharged from the back pressure chamber 20. Note that the effective diameter of the diaphragm 38 is set larger than the effective diameter of the diaphragm 34. For this reason, when the back pressure discharge channel C is opened, the discharge flow rate from the back pressure chamber 20 becomes larger than the supply flow rate to the back pressure chamber 20.

  Then, the fuel is supplied to the back pressure chamber 20 through the back pressure supply channel B, or the fuel is discharged from the back pressure chamber 20 through the back pressure discharge channel C. The fuel pressure (back pressure) can be increased or decreased. Further, by adjusting the back pressure in this way, the strength of the opening biasing force that biases the valve body 5 in the opening direction and the closing biasing force that biases the valve body 5 in the closing direction is adjusted. can do.

  The back pressure discharge channel C is opened and closed by operating and stopping the injection control valve 8. That is, when the solenoid 23 is energized, the valve body 24 opens the upstream side of the valve chamber 28, and the back pressure discharge channel C is opened. When the energization of the solenoid 23 is stopped, the valve body 24 closes the upstream side of the valve chamber 28, and the back pressure discharge channel C is closed.

  As a result, when the injection control valve 8 is operated, fuel flows out from the back pressure chamber 20 and the back pressure is reduced. For this reason, the urging force for urging the valve body 5 is stronger in the opening urging force than in the closing urging force, and the valve body 5 is separated from the seat surface 21 to open the nozzle hole 6. When the injection control valve 8 stops operating, fuel flows into the back pressure chamber 20 and the back pressure increases. For this reason, the urging force for urging the valve body 5 is stronger in the closing urging force than in the opening urging force, and the valve body 5 is seated on the seat surface 21 and closes the injection hole 6.

  The flow path e is connected to the flow path d, and forms a high pressure discharge flow path D for discharging the fuel in the high pressure supply flow path A together with the flow path d and the low pressure pipe 16 downstream from the connection point. The channel e is provided with a throttle 39 as an emission regulating means for regulating the discharge of fuel from the high pressure supply channel A. Then, the discharge flow rate is regulated by the throttle 39. The flow path e incorporates a check valve 40 that opens when a pressure higher than atmospheric pressure is applied. The check valve 40 includes a valve member 41 that opens and closes the flow path e, and a spring 42 that biases the valve member 41 in a direction to close the flow path e.

  As will be described later, the valve opening pressure of the check valve 40 is preferably as low as possible in order to make the pressure (injection pressure) of the fuel injected from the nozzle hole 6 higher by pressure pulsation. For this reason, the valve opening pressure of the check valve 40 is set to be slightly higher than the atmospheric pressure.

  The fuel cutoff valve 3 is a two-way valve that switches between a valve open state in which the common rail 4 and the high pressure pipe 15 communicate with each other and a valve closed state in which the common rail 4 and the high pressure pipe 15 are shut off. Further, as shown in FIG. 3, the fuel cutoff valve 3 is fastened and fixed by a retaining nut 46 and attached to the common rail 4. In response to a command from the ECU, the fuel shut-off valve 3 includes a solenoid 47 that receives power from a vehicle-mounted power source and generates a magnetic attractive force, a valve body 48 that is attracted and displaced by the magnetic attractive force, and the valve body 48 as a magnetic attractive force It consists of a return spring 49 that biases in the opposite direction, a body 51, and the like. The body 51 is provided with valve chambers 52a and 52b that are blocked or communicated by the displacement of the valve body 48, and flow paths 53a and 53b that open to the valve chambers 52a and 52b, respectively.

  The common rail 4 has an upstream flow path 55 that opens to the pressure accumulation chamber 54 where high-pressure fuel is accumulated and is connected to the flow path 53a, and a downstream flow path 56 that connects the high-pressure pipe 15 and the flow path 53b. Is provided. As described above, the fuel cutoff valve 3 is incorporated at the uppermost stream end of the high-pressure supply flow path A, closes the high-pressure supply flow path A, and opens the high-pressure supply flow path A in accordance with a command from the ECU.

  That is, when the solenoid 47 is energized, the valve body 48 is displaced to a position where the valve chamber 52a and the valve chamber 52b communicate with each other. When the energization of the solenoid 47 is stopped, the valve body 48 is displaced to a position where the valve chamber 52a and the valve chamber 52b are blocked.

  As a result, when the fuel cutoff valve 3 is activated (when the solenoid 47 is energized), the high pressure supply passage A is opened to the common rail 4, and the fuel in the pressure accumulating chamber 54 is downstream of the fuel cutoff valve 3. To the high pressure supply channel A on the side. At this time, if the nozzle hole 6 is closed, the fuel pressure is reflected at the most downstream end of the high-pressure supply channel A (that is, the position where the valve body 5 is seated on the seat surface 21). For this reason, pressure pulsation occurs in the high-pressure supply flow path A, and the maximum value of the fuel pressure in the high-pressure supply flow path A is higher than the fuel pressure (common rail pressure) in the pressure accumulation chamber 54.

[Injection Method of Example 1]
The injection method of Example 1 is demonstrated using FIG.
First, as shown in FIG. 4A, the fuel cutoff valve 3 is temporarily opened at time t1 in accordance with a command from the ECU. As a result, the fuel accumulated in the common rail 4 is temporarily guided to the high-pressure supply channel A.

  As a result, as shown in FIG. 4B, the fuel pressure (corresponding to the injection pressure) in the high-pressure supply passage A becomes higher than the common rail pressure due to pressure pulsation. Thus, when the injection pressure is increased by pressure pulsation and is higher than the common rail pressure (time t2), as shown in FIGS. 4 (c) and 4 (d), the injection hole 6 is opened in accordance with a command from the ECU. The injection supply to the engine begins. At time t3, the nozzle hole 6 is closed in response to a command from the ECU, and the supply of injection to the engine ends.

  When the fuel pressure in the high pressure supply passage A increases, the check valve 40 in the high pressure discharge passage D is opened, and fuel discharge from the high pressure supply passage A to the high pressure discharge passage D starts. However, since the discharge flow rate is regulated by the throttle 39, the influence on the increase in the injection pressure is kept low.

  Even after the end of injection (that is, after time t3), the pressure pulsation remains because the throttle 39 restricts the discharge flow rate of the increased pressure in the high pressure supply passage A. However, the pressure pulsation is gradually attenuated, and the fuel pressure in the high-pressure supply passage A is reduced to the valve opening pressure of the check valve 40 (which is substantially equal to the atmospheric pressure). As a result, the pressure of the fuel in the high-pressure supply flow path A is sufficiently reduced by the start of the next injection, and the injection pressure can be increased by the pressure pulsation even in the next injection.

[Effect of Example 1]
The fuel injection device 1 according to the first embodiment includes a nozzle 7 that injects fuel by opening and closing an injection hole 6 by movement of a valve body 5, and an injection control valve 8 that drives the valve body 5. The fuel injection valve 2 for supplying the injected fuel to the engine and the high pressure supply passage A for guiding the fuel from the common rail 4 to the injection hole 6 are closed, the high pressure supply passage A is closed, and if necessary And a fuel cutoff valve 3 that opens the high-pressure supply channel A.
Thereby, the fuel cutoff valve 3 is temporarily opened, and the pressure pulsation can be generated by temporarily guiding the fuel to the high-pressure supply passage A on the downstream side of the fuel cutoff valve 3. The pressure pulsation can increase the fuel pressure in the high-pressure supply channel A. For this reason, the injection pressure can be increased by a simple structure in which the fuel cutoff valve 3 is incorporated in the high-pressure supply passage A.

In the fuel injection device 1, the high pressure discharge channel D for discharging the fuel in the high pressure supply channel A is branched from the high pressure supply channel A.
When the pressure of the fuel is increased by pressure pulsation, the flow path through which the fuel is temporarily guided, that is, the flow path that generates pressure pulsation is preferably as low as possible. Therefore, as described above, if the high-pressure discharge flow path D for discharging the fuel is branched from the high-pressure supply flow path A that is a flow path for generating pressure pulsation, the high-pressure supply flow path A is lowered. Can do.

The high pressure discharge channel D is provided with a throttle 39 as a discharge regulating means for regulating the discharge of fuel from the high pressure supply channel A, and the discharge flow rate is regulated by the throttle 39.
Thereby, when using the high pressure supply flow path A for the original purpose, such as injecting the pressure-increased fuel from the nozzle 7, the influence of the fuel discharge from the high pressure discharge flow path D can be reduced.

The high-pressure discharge channel D incorporates a check valve 40 that opens when a pressure slightly higher than atmospheric pressure is applied.
The pressure of the fuel in the high pressure supply passage A after the pressure increase due to the pressure pulsation becomes higher as the fuel pressure in the high pressure supply passage A before the fuel shut-off valve 3 is opened is lower. According to the above configuration, since the valve opening pressure of the check valve 40 is set to be slightly higher than the atmospheric pressure, the pressure of the fuel in the high pressure supply passage A after the injection is almost atmospheric pressure. To fall. For this reason, the injection pressure after the pressure increase due to the pressure pulsation can be increased to a value close to the maximum value at which the pressure can be increased.

In the fuel injection device 1, a back pressure chamber 20 that receives supply of fuel that exerts pressure on the valve body 5 in the closing direction is formed, and a back pressure supply flow path B for supplying fuel to the back pressure chamber 20 includes: Branches from the high-pressure supply channel A. The back pressure supply flow path B incorporates a check valve 35 that prevents back flow of fuel from the back pressure chamber 20 to the high pressure supply flow path A.
When the nozzle hole 6 is closed, the closing biasing force that biases the valve element 5 in the closing direction is stronger than the opening biasing force that biases the valve element 5 in the opening direction. When the opening urging force becomes stronger than the closing urging force, the valve body 5 moves in the opening direction to open the injection hole 6. In response to such an operation of the valve body 5, the biasing force due to the back pressure forms a closing hole biasing force. For this reason, if the fuel flows out from the back pressure chamber 20 during the time when the injection should be stopped, the balance of the urging force in the valve body 5 may be lost and unintended injection may be performed. Therefore, by incorporating a check valve 35 that prevents the backflow of fuel from the back pressure chamber 20 to the high pressure supply passage A into the back pressure supply passage B, unintended injection can be reliably prevented.

The fuel cutoff valve 3 is mounted on the common rail 4.
In the high-pressure supply channel A, the injection pressure after pressure increase due to pressure pulsation can be increased as the fuel cutoff valve 3 is incorporated further upstream. Therefore, the fuel cutoff valve 3 is mounted on the common rail 4 as described above, and the fuel cutoff valve 3 is incorporated in the vicinity of the common rail 4 corresponding to the most upstream end of the high-pressure supply flow path A. Thereby, the injection pressure after pressure increase due to pressure pulsation can be increased. Further, the work for assembling the fuel cutoff valve 3 to the fuel injection device 1 is facilitated, and the number of manufacturing steps of the fuel injection device 1 can be reduced.

According to the injection method of the first embodiment, the fuel shut-off valve 3 is temporarily opened, the fuel is temporarily guided from the common rail 4 to the high-pressure supply passage A to generate pressure pulsation, and the high-pressure supply passage A When the pressure of the fuel led to is increased by pressure pulsation, the nozzle hole 6 is opened.
Thus, the injection pressure can be increased and the increased fuel can be injected and supplied to the engine with a simple structure in which the fuel cutoff valve 3 is incorporated in the high-pressure supply passage A.

[Configuration of Example 2]
The configuration of the fuel injection device 1 according to the second embodiment will be described with reference to FIGS. In addition, the same code | symbol is used for the element similar to Example 1, and description is abbreviate | omitted.
As shown in FIGS. 5 and 6, in addition to the high-pressure pipe 15, a second low-pressure pipe 58 that is open to the atmosphere is connected to the fuel cutoff valve 3 of the second embodiment. The fuel cutoff valve 3 according to the second embodiment is a three-way valve that switches between a valve open state in which the common rail 4 and the high pressure pipe 15 communicate with each other and a valve closed state in which the high pressure pipe 15 and the second low pressure pipe 58 communicate with each other. .

  In the common rail 4 of the second embodiment, as shown in FIG. 7, in addition to the upstream and downstream channels 55 and 56, a second downstream channel 59 connected to the second low-pressure pipe 58 is provided. . In addition, the body 51 of the fuel cutoff valve 3 according to the second embodiment is provided with three flow paths 60, 61 and 62 whose communication state is switched by the valve body 48. That is, the flow path 60 is connected to the upstream flow path 55 of the common rail 4 and opens to the valve chamber 52 a, and always communicates with the pressure accumulation chamber 54. The flow path 61 is connected to the downstream flow path 56 of the common rail 4 and opens to the valve chamber 52 b, and always communicates with the high-pressure pipe 15 through the downstream flow path 56, and the flow path 62 is the second of the common rail 4. It connects to the downstream flow path 59 and opens to the valve chamber 52 b, and always communicates with the second low-pressure pipe 58 via the second downstream flow path 59.

  When the solenoid 47 is energized, the valve body 48 is displaced to a position where the valve chamber 52a and the valve chamber 52b communicate with each other, and the opening of the flow path 62 is closed. As a result, the flow path 60 and the flow path 61 communicate with each other, and the common rail 4 and the high-pressure pipe 15 communicate with each other. For this reason, the fuel cutoff valve 3 is opened. When the energization of the solenoid 47 is stopped, the valve body 48 is displaced to a position where the valve chamber 52a and the valve chamber 52b are blocked, and the opening of the flow path 62 is opened. As a result, the flow path 61 and the flow path 62 communicate with each other, and the high-pressure pipe 15 and the second low-pressure pipe 58 communicate with each other. For this reason, the fuel cutoff valve 3 is closed.

  As a result, when the fuel shut-off valve 3 is actuated (when the solenoid 47 is energized), the high pressure supply passage A is opened to the common rail 4 and the fuel in the pressure accumulating chamber 54 is guided to the high pressure supply passage A. It is burned. As a result, pressure pulsation occurs in the high pressure supply passage A, and the maximum value of the fuel pressure in the high pressure supply passage A becomes higher than the common rail pressure. Further, when the operation of the fuel cutoff valve 3 is stopped, the high pressure supply passage A is opened to the atmosphere via the second low pressure layout 58. As a result, fuel is discharged from the high-pressure supply channel A, and the pressure of the fuel in the high-pressure supply channel A is reduced to approximately atmospheric pressure.

  Thus, in the second embodiment, the second low pressure pipe 58 forms the high pressure discharge channel D. For this reason, the flow path e (see FIG. 2) provided to form the high-pressure discharge flow path D is not provided in the second embodiment.

  Further, in the second embodiment, as soon as the fuel cutoff valve 3 is switched from the open state to the closed state, the fuel pressure in the high pressure supply passage A is reduced to atmospheric pressure. Therefore, even if the back pressure decreases during the time period when the injection should be stopped, the possibility that unintended injection will occur is extremely low. For this reason, the check valve 35 (see FIG. 2) incorporated in the flow path b forming the back pressure supply flow path B is not incorporated in the second embodiment.

[Injection Method of Example 2]
The injection method of Example 2 is demonstrated using FIG.
First, as shown in FIG. 8A, the fuel shut-off valve 3 is opened at time t1 in accordance with a command from the ECU. As a result, the fuel accumulated in the common rail 4 is guided to the high pressure supply passage A.

  As a result, as shown in FIG. 8B, the injection pressure becomes higher than the common rail pressure due to pressure pulsation. Thus, when the injection pressure is increased by pressure pulsation and becomes higher than the common rail pressure (time t2), as shown in FIGS. 8 (c) and 8 (d), the injection hole is in response to a command from the ECU. 6 is opened and the injection supply to the engine starts. At time t3, the nozzle hole 6 is closed in response to a command from the ECU, and the supply of injection to the engine ends.

  Then, at time t4 after the end of injection, the fuel cutoff valve 3 is closed according to a command from the ECU. Thereby, the fuel in the high pressure supply passage A is discharged through the second low pressure pipe 58. For this reason, the pressure pulsation of the high-pressure supply channel A rapidly disappears, and the fuel pressure in the high-pressure supply channel A decreases to approximately atmospheric pressure.

[Effect of Example 2]
The fuel cutoff valve 3 of the fuel injection device 1 according to the second embodiment is a valve closing state in which the common rail 4 and the high-pressure pipe 15 communicate with each other and the high-pressure pipe 15 and the second low-pressure pipe 58 opened to the atmosphere communicate with each other. It is a three-way valve that switches between states.
Thereby, the high-pressure supply flow path A can be reliably made into a low pressure by switching the fuel cutoff valve 3 from an open state to a closed state after completion | finish of injection.

[Configuration of Example 3]
The configuration of the fuel injection device 1 according to the third embodiment will be described with reference to FIGS. 9 to 10. In addition, the same code | symbol is used for the element similar to Example 1, and description is abbreviate | omitted.
In the third embodiment, as shown in FIGS. 9 and 10, in addition to the high-pressure pipe 15, the second for supplying fuel directly from the common rail 4 to the fuel injection valve 2 without going through the fuel cutoff valve 3. A high pressure pipe 65 is provided. The main body 12 of the fuel injection valve 2 is provided with a flow path f that connects the second high-pressure pipe 65 and the back pressure chamber 20, and the flow path f together with the second high-pressure pipe 65 is a back pressure supply flow path B. Make.

  As described above, in Example 3, the back pressure supply flow path B including the second high pressure pipe 65 and the flow path f is separated from the high pressure supply flow path A including the high pressure pipe 15 and the flow path a from the common rail 4. It is directly connected to the back pressure chamber 20. For this reason, the flow path b (refer FIG. 2) provided in order to make the back pressure supply flow path B is not provided in Example 3. FIG. In the third embodiment, the high-pressure fuel accumulated in the common rail 4 is always supplied to the back pressure chamber 20 via the second high-pressure pipe 65 and the flow path f. Therefore, the possibility that unintentional injection occurs due to a decrease in back pressure is extremely low. For this reason, the check valve 35 (see FIG. 2) incorporated in the flow path b is not incorporated in the third embodiment.

  Further, the back pressure chamber 20 of the third embodiment is closed at the bottom by the piston 66. The piston 66 receives the back pressure and is urged in the closing direction, contacts the valve body 5, and transmits the back pressure to the valve body 5 to urge the valve body 5 in the closing direction. The spring 22 is housed in a spring chamber 67 formed separately from the back pressure chamber 20.

  The effective pressure receiving area of the injection pressure acting on the valve body 5 in the opening direction is smaller than the effective pressure receiving area of the back pressure acting on the piston 66 in the closing direction. Here, since the back pressure acting on the piston 66 in the closing direction is transmitted to the valve body 5 as it is, the “effective pressure receiving area of the injection pressure acting on the piston 66 in the closing direction” is “the valve body. 5 is equal to the “effective pressure receiving area of back pressure acting in the closing direction”. Therefore, the effective pressure receiving area of the injection pressure acting on the valve body 5 in the opening direction is smaller than the effective pressure receiving area of the back pressure acting on the valve body 5 in the closing direction.

[Injection Method of Example 3]
The injection method of Example 3 is demonstrated using FIG.
In the third embodiment, as shown in FIGS. 11C and 11D, after the injection hole 6 is opened for a predetermined time and the injection is finished, the fuel is obtained at time t4 as shown in FIG. 11A. The shut-off valve 3 is temporarily opened again. Thereby, the remaining fuel increased in pressure by the pressure pulsation is guided upstream of the fuel cutoff valve 3. For this reason, as shown in FIG. 11B, after time t4, the pressure of the fuel in the high pressure supply passage A is suppressed to a pressure lower than the common rail pressure and gradually attenuates to open the check valve 40. (It is almost equivalent to atmospheric pressure). The time t4 substantially coincides with the time for the high-pressure reflected wave to reach the fuel cutoff valve 3. As a result, it is possible to pass the high-voltage reflected wave to the common rail 4 side and to prevent it from coming out again to the high-pressure supply flow path A side.

[Effect of Example 3]
In the fuel injection device 1 according to the third embodiment, a second high-pressure pipe 65 different from the high-pressure pipe 15 is incorporated between the common rail 4 and the fuel injection valve 2, and fuel is directly supplied from the common rail 4 to the back pressure chamber 20. Have been supplied.
As a result, high-pressure fuel can be supplied to the back pressure chamber 20 without going through the high-pressure supply flow path A for guiding the fuel from the common rail 4 to the nozzle hole 6. For this reason, since it is not necessary to supply a part of the injected fuel to the back pressure chamber 20, it is possible to prevent an unintended drop in the injection pressure.

In the fuel injection device 1, the effective pressure receiving area of the injection pressure acting on the valve body 5 in the opening direction is smaller than the effective pressure receiving area of the back pressure acting on the valve body 5 in the closing direction.
The injection pressure is increased to a pressure higher than the common rail pressure by pressure pulsation. Therefore, when fuel is supplied from the common rail 4 to the back pressure chamber 20 via a flow path (back pressure supply flow path B) different from the high pressure supply flow path A, the back pressure acting in the closing direction is opened. There is a possibility that it may become lower than the injection pressure acting in the hole direction. Therefore, as described above, the effective pressure receiving area of the injection pressure acting on the valve body 5 in the opening direction is made smaller than the effective pressure receiving area of the back pressure acting on the valve body 5 in the closing direction. Thereby, the closing biasing force due to the back pressure can be made stronger than the opening biasing force due to the injection pressure. For this reason, even if the back pressure is lower than the injection pressure, the valve body 5 can be urged in the closing direction to close the injection hole 6 more reliably.

According to the injection method of the third embodiment, after the injection is completed, the fuel cutoff valve 3 is temporarily opened again, and the increased fuel is guided upstream of the fuel cutoff valve 3.
As a result, the increased residual fuel can be recovered in the common rail 4 to suppress energy loss, and the pressure of the fuel in the high pressure supply passage A after the injection can be reduced.

[Modification]
Although the fuel cutoff valve 3 of this embodiment is mounted on the common rail 4, it may be incorporated in the high-pressure pipe 15 or mounted on the fuel injection valve 2.
In the first and third embodiments, the throttle 39 is provided as the discharge restricting means. However, the present invention is not limited to this mode. For example, the opening degree is changed according to the discharge flow rate, the pressure of the discharged fuel, and the like. A variable opening mechanism that can be used may be provided as the discharge restricting means.
Further, the fuel injection method of the third embodiment can be applied to the fuel injection device 1 of the first and second embodiments.
Also in the injection method of the second embodiment, the time t4 may be substantially coincident with the time for the high-pressure reflected wave to reach the fuel cutoff valve 3, as in the injection method of the third embodiment.
In the fuel injection device 1 according to the third embodiment, the effective pressure receiving area of the injection pressure acting on the valve body 5 in the opening direction is larger than the effective pressure receiving area of the back pressure acting on the valve body 5 in the closing direction. Although it was small, it is not limited to this. That is, the effective pressure receiving area of the injection pressure acting on the valve body 5 in the opening direction and the effective pressure receiving area of the back pressure acting on the valve body 5 in the closing direction may be the same size. On the other hand, the effective pressure receiving area of the injection pressure acting in the opening direction may be larger than the effective pressure receiving area of the back pressure acting on the valve body 5 in the closing direction.

1 is a configuration diagram of a fuel injection device (Example 1). FIG. (Example 1) which is a block diagram of a fuel injection valve. It is a block diagram of a common rail and a fuel cutoff valve (Example 1). (A) is a time chart of the open / close state of the fuel cutoff valve, (b) is a time chart of the injection pressure, (c) is a time chart of the open / close state of the fuel injection valve, and (d) is the injection rate. (Example 1). (Example 2) which is a block diagram of a fuel-injection apparatus. (Example 2) which is a block diagram of a fuel injection valve. (Example 2) which is a block diagram of a common rail and a fuel cutoff valve. (A) is a time chart of the open / close state of the fuel cutoff valve, (b) is a time chart of the injection pressure, (c) is a time chart of the open / close state of the fuel injection valve, and (d) is the injection rate. (Example 2). (Example 3) which is a block diagram of a fuel-injection apparatus. (Example 3) which is a block diagram of a fuel injection valve. (A) is a time chart of the open / close state of the fuel cutoff valve, (b) is a time chart of the injection pressure, (c) is a time chart of the open / close state of the fuel injection valve, and (d) is the injection rate. (Example 3).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection apparatus 2 Fuel injection valve 3 Fuel cutoff valve 4 Common rail (fuel supply source)
5 Valve body 6 Injection hole 7 Nozzle 8 Injection control valve (actuator)
20 Back pressure chamber 35 Check valve 39 Restriction (discharge regulation means)
40 Check valve A High pressure supply channel B Back pressure supply channel D High pressure discharge channel

Claims (12)

A nozzle that opens and closes the nozzle hole by the movement of the valve body and injects fuel, and a back pressure chamber on the side opposite to the nozzle hole of the valve body, the back pressure of the back pressure chamber is controlled to drive the valve body A fuel injection valve that injects fuel supplied from a predetermined fuel supply source to the engine;
A fuel cutoff valve that is incorporated in a high-pressure supply passage for guiding fuel from the fuel supply source to the nozzle hole, closes the high-pressure supply passage, and opens the high-pressure supply passage as necessary; In the fuel injection device provided,
The fuel shut-off valve is a two-way valve that switches between a valve open state in which the fuel supply source and the high pressure supply flow path are in communication with each other and a valve closed state in which the fuel supply source and the high pressure supply flow path are shut off. There,
The fuel shut-off valve is temporarily opened, and pressure pulsation is generated by temporarily guiding fuel from the fuel supply source to the downstream side of the fuel shut-off valve,
The fuel injection device, wherein the nozzle hole is opened when the pressure of the fuel guided downstream from the fuel cutoff valve is increased by the pressure pulsation. The fuel injection device according to claim 1,
A fuel injection device, wherein a high-pressure discharge channel for discharging fuel in the high-pressure supply channel branches from the high-pressure supply channel. The fuel injection device according to claim 2, wherein
The fuel injection apparatus according to claim 1, wherein the high-pressure discharge passage is provided with discharge restriction means for restricting fuel discharge. The fuel injection device according to claim 3, wherein
The fuel injection device, wherein the discharge restricting means restricts a discharge flow rate by a throttle provided in the high pressure discharge flow path. The fuel injection device according to claim 2, wherein
A fuel injection device, wherein a check valve that opens when a pressure higher than atmospheric pressure is applied is incorporated in the high-pressure discharge passage. A nozzle that opens and closes the nozzle hole by the movement of the valve body and injects fuel, and a back pressure chamber on the side opposite to the nozzle hole of the valve body, the back pressure of the back pressure chamber is controlled to drive the valve body A fuel injection valve that injects fuel supplied from a predetermined fuel supply source to the engine;
A fuel cutoff valve that is incorporated in a high-pressure supply passage for guiding fuel from the fuel supply source to the nozzle hole, closes the high-pressure supply passage, and opens the high-pressure supply passage as necessary; In the fuel injection device provided,
The fuel shut-off valve communicates between a valve open state in which the fuel supply source and the high-pressure supply flow path communicate with each other and a high-pressure discharge flow path for discharging fuel in the high-pressure supply flow path. A three-way valve that switches between a closed state and a closed state,
The fuel shut-off valve is temporarily opened, and pressure pulsation is generated by temporarily guiding fuel from the fuel supply source to the downstream side of the fuel shut-off valve,
The fuel injection device, wherein the nozzle hole is opened when the pressure of the fuel guided downstream from the fuel cutoff valve is increased by the pressure pulsation. The fuel injection device according to claim 1 or 6,
A fuel injection device, wherein a back pressure supply passage for supplying fuel to the back pressure chamber branches from the high pressure supply passage. The fuel injection device according to claim 7, wherein
The fuel injection device according to claim 1, wherein a check valve for preventing a back flow of fuel from the back pressure chamber to the high pressure supply channel is incorporated in the back pressure supply channel. The fuel injection device according to claim 1 or 6,
A fuel injection, wherein a back pressure supply passage for supplying fuel to the back pressure chamber is directly connected to the back pressure chamber from the fuel supply source separately from the high pressure supply passage. apparatus. The fuel injection device according to claim 9, wherein
Fuel injected from the nozzle hole is supplied to the nozzle from the high-pressure supply channel so as to exert pressure on the valve body in a direction to open the nozzle hole,
The fuel injection device, wherein an effective pressure receiving area of the pressure of the fuel acting in the direction of opening the nozzle hole with respect to the valve body is smaller than an effective pressure receiving area of the back pressure. The fuel injection device according to claim 1 or 6,
The fuel supply source has a fuel injection pump that discharges the fuel at a high pressure, a common rail that accumulates fuel discharged from the fuel injection pump at a predetermined pressure,
The fuel injection device, wherein the fuel cutoff valve is attached to the common rail. A nozzle that opens and closes the nozzle hole by the movement of the valve body and injects fuel, and a back pressure chamber on the side opposite to the nozzle hole of the valve body, the back pressure of the back pressure chamber is controlled to drive the valve body A fuel injection valve that injects fuel supplied from a predetermined fuel supply source to the engine;
A fuel cutoff valve that is incorporated in a high-pressure supply passage for guiding fuel from the fuel supply source to the nozzle hole, closes the high-pressure supply passage, and opens the high-pressure supply passage as necessary; A fuel injection method using the provided fuel injection device,
The fuel shut-off valve is temporarily opened, and pressure pulsation is generated by temporarily guiding fuel from the fuel supply source to the downstream side of the fuel shut-off valve,
When the pressure of the fuel guided downstream from the fuel shutoff valve is increased by the pressure pulsation, the nozzle hole is opened,
After a lapse of a predetermined time, the actuator is deactivated and the nozzle hole is closed by the valve body. Then, the fuel shut-off valve is temporarily opened again, and the fuel increased in pressure by the pressure pulsation is shut off from the fuel. A fuel injection method, wherein the fuel injection method is guided upstream of the valve.

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