JPH1113592A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an initial injection rate stably without being influenced by an operating state and fuel itself and close a valve rapidly at the time of completing injection so as to improve injection cutoff (sharp cutoff), thereby preventing worsening of combustion and an exhaust gas level. SOLUTION: A fuel injection valve 5 is provided with a cylindrical body 22 having a fuel injection hole 21 at the tip, and a valve element 23 provided inside the cylindrical body 22 so as to be movable forward and backward. The valve element 23 is advanced by the pressure of high pressure fuel, led into the cylindrical body 22, so as to close the fuel injection hole 21, and high pressure fuel is discharged from the cylindrical body 22 to retreat the valve element 23, thereby opening the fuel injection hole 21. The fuel injection valve 5 of such constitution is further provided with an inertial mass body 25 provided as a separate body from the valve element 23, an engaging part 23c provided on the outer periphery of the valve element 23 and engaged with the inertial mass body 25 when the valve element 23 retreats, and an energizing means 24 for energizing the engaging part 23c and furthermore the valve element 23 in the advancing direction through the inertial mass body 25 when the valve element 23 retreats. The valve element 23 therefore retreats moderately at the time of starting injection, and the valve element 23 advances rapidly at the time of completing injection so as to suppress worsening of emission.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection valve that opens and closes a fuel injection hole by controlling the pressure of high-pressure fuel introduced therein to move a valve body back and forth.

[0002]

2. Description of the Related Art For example, a pressure accumulating type (common rail type) fuel injection device for a diesel engine introduces high-pressure fuel supplied from a pressure accumulating chamber into a control chamber provided inside a main body of the fuel injection valve, and the fuel injection valve is controlled by the fuel injection valve. The valve body (needle valve) is advanced (lowered), and this needle valve is kept in a normally closed state.
By leaking the fuel in the control chamber to the fuel discharge path and reducing the pressure in the control chamber, the needle valve retreats (rises) and opens the fuel injection hole to perform the fuel injection.

[0003] In the case of a Hall type injection nozzle, as shown in FIG.
The valve element 23 is a needle valve having a conical tip, and the fuel injection hole 21 is opened and closed by the reciprocating movement of the needle valve.

That is, the needle valve 23 retreats (rises).
Then, when the flow path to the fuel injection hole 21 is opened, the fuel flows through the gap between the tip of the needle valve 23 and the main body 22 and is ejected from the fuel injection hole 21, and if the needle valve 23 advances (downs), The flow path to the fuel injection hole 21 is closed.

[0005] The fuel injection is divided into the initial injection, the fully opened needle valve 23, and the end of injection. The fuel injection rate, which indicates the relationship between the fuel injection amount and the injection period, is set at the initial injection, needle injection It differs when the valve 23 is fully opened and when the injection is completed.

That is, during the initial injection, the needle valve 23
A period in which the flow path area Sp, which is the minimum flow path cross-sectional area in the gap between the front end and the main body 22, is smaller than the cross-sectional area (sum of the injection hole areas) Sf of the fuel injection holes 21 (Sp <Sf). At the time, the fuel injection rate is defined by the flow path area Sp.

When the needle valve 23 is fully opened, the flow path area Sp to the fuel injection hole 21 is larger than the sectional area Sf of the fuel injection hole 21 (Sp> Sf), and the valve is fully opened. When the needle valve 23 is fully opened, the fuel injection rate is determined by the sectional area Sf of the fuel injection hole 21.

At the end of the injection, Sp <Sf, as in the initial injection, and the fuel injection rate is defined by the flow path area Sp. As described above, the fuel injection rate depends on the valve opening at the tip of the needle valve 23 of the fuel injection valve at the time of initial injection and at the end of injection, and depends on the size of the fuel injection hole when the needle valve 23 is fully open. .

The fuel injection valve has a flow path for fuel introduced into a control chamber of the fuel injection valve (hereinafter referred to as an IN flow path) and a flow path for fuel leaked from the control chamber to a fuel discharge path (hereinafter referred to as a flow path). OU
T), and the ratio of the cross-sectional area A of the IN flow path to the cross-sectional area B of the OUT flow path is usually fixed at A: B = 2: 3 or 1: 2. .

The fuel injection rate of the fuel injection valve exhibits, for example, the characteristics shown in FIG. 8 depending on the ratio of the flow path cross-sectional area A of IN to the flow path cross-sectional area B of OUT. That is,
When the cross-sectional area A of the IN is fixed to be smaller than the cross-sectional area B of the OUT, the lift speed of the needle valve becomes steep when the needle valve is opened as shown by the solid line in FIG. As a result, the fuel injection rate in the early stage of the fuel injection increases, and when the needle valve is closed, the valve closing speed of the needle valve is defined by both the fuel supply pressure and the flow path cross-sectional area A of IN.

Conversely, when the flow path cross-sectional area A of IN is largely fixed with respect to the flow cross-sectional area B of OUT, the regression speed of the needle valve becomes slow as shown by the dashed line in FIG. As a result, the fuel injection rate in the early stage of fuel injection gradually increases, and when the needle valve is closed, the fuel supply pressure and the flow path cross-sectional area A of IN
Both define the closing speed of the needle valve.

In the characteristic diagram of the fuel injection rate shown in FIG. 8, the vertical axis indicates the fuel injection amount and the horizontal axis indicates the fuel injection time. As described above, the fuel injection rate also differs depending on the ratio between the flow path cross-sectional area A of IN and the flow path cross-sectional area B of OUT.

Therefore, even if the fuel injection device supplies an appropriate amount of fuel at an appropriate time to a fuel injection valve connected at a high pressure,
The fuel injection rate at the time of initial injection or at the end of injection depends on the speed at which the needle valve moves forward and backward.

[0014]

By the way, as shown by the solid line in FIG. 8A, during the initial injection of the needle valve, if the retreat (rise) speed of the needle valve becomes steep, the retreat speed becomes too fast, The injection rate is too high than the required initial injection rate of the engine. As described above, when the initial injection rate is high, the amount of fuel injected during the ignition delay period increases, the rate of premixed combustion (explosive combustion) of diesel increases, the combustion noise deteriorates, and the exhaust gas level deteriorates ( (NOx increase).

Therefore, a device for delaying the retreat speed of the needle valve has been proposed. For example, Japanese Utility Model Application Hei 5-614
The fuel injection device for a diesel engine disclosed in Japanese Patent Application Laid-Open Publication No. 9-29980 has a one-way orifice that delays the discharge of high-pressure fuel to a fuel discharge port in a flow path at an inlet / outlet to a control room. By narrowing the diameter of the one-way orifice, the discharge of high-pressure fuel is delayed, and the lift speed of the needle valve is reduced as shown by the one-dot chain line in FIG. 8B.

However, when the fuel (fluid) itself flowing into and out of the control chamber of the fuel injection valve itself is directly used for delaying the regression of the needle valve as in the device disclosed in Japanese Utility Model Application Laid-Open No. 5-6149, for example, it changes depending on the operating condition. When the fuel temperature changes easily, the viscosity changes, and the flow rate of the fuel flowing through the one-way orifice changes. This causes a problem in that the retreat speed of the needle valve varies and the retreat speed becomes unstable.

Also, at the end of injection of the needle valve, in the conventional fuel injection valve, if the fuel (fluid) itself flowing into and out of the control chamber of the fuel injection valve is directly used for advancement of the needle valve, the one-way orifice is opened. When the valve amount or the viscosity changes, the flow speed of the fuel flowing through the one-way orifice changes, which causes a problem in that the advance speed of the needle valve varies, and the advance speed becomes unstable.

In general, when the advance (closing) speed of the needle valve is low, when the same injection amount is injected, the injection period becomes long, so that the isovolume is reduced and the output is reduced.
Then, there arises a problem that the afterburning rate increases, which leads to an increase in the amount of smoke and the emission of particulates.

In view of the foregoing, the present invention stably suppresses the initial injection rate without being affected by the operating state or the fuel itself, and closes the valve quickly at the end of the injection to cut off the injection (sharp cut). And to provide a fuel injection valve which prevents deterioration of combustion and exhaust gas level.

[0020]

The present invention adopts the following means in order to solve the above-mentioned problems. That is, the fuel injection device of the present invention has a main body having a fuel injection hole at the tip,
A valve body provided movably forward and backward within the main body,
The fuel is advanced by causing the valve body to advance with the pressure of the high-pressure fuel introduced into the main body, closing the fuel injection hole, discharging high-pressure fuel from within the main body, retreating the valve body, and opening the fuel injection hole. In the injection valve, an inertial mass body provided separately from the valve body, an engaging portion provided on the valve body and engaging with the inertial mass body when the valve body retreats, and the valve body retreats. And a biasing means for biasing the valve body in the advance direction via the inertial mass body which engages with the engagement portion and retreats together with the valve body.

According to the above configuration, when the valve body retreats (opens), the valve body and the inertial mass body move integrally, and the presence of the inertial mass body causes the valve body to move. The regression speed is delayed. On the other hand, when the valve element advances (closes), the valve element and the inertial mass body advance separately.

Therefore, at the start of the injection, the valve body slowly retreats (opens), and the initial injection rate can be stably suppressed to a low level to suppress combustion noise. At the end of the injection, the valve body quickly advances ( (Close the valve) to improve the cut-off of injection and suppress deterioration of emission.

Further, the fuel injection valve of the present invention preferably further comprises a prohibiting means for prohibiting the urging of the urging means until the valve element retreats by a predetermined amount when the valve element retreats. It is characterized by the following.

When such a prohibiting means is used, the urging force in the advance direction is applied stepwise to the valve body, so that two-stage injection can be realized.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described.
This will be described with reference to the drawings. <Overall Configuration of Fuel Injection Device> First, a fuel injection device that supplies fuel to the fuel ejection valve 5 will be described.

The fuel injection device shown in FIG. 1 is a pressure-accumulation type (common rail type) fuel injection device of a diesel engine which is a general fuel injection device. This device pumps fuel from a fuel tank 1 as a fuel supply source and sends out the fuel at a predetermined pressure (rotary supply pump).
And the fuel sent from the fuel pump 2
A fuel pressure accumulating chamber 3 for accumulating pressure to a predetermined supply pressure is provided.

A plurality of fuel supply passages 4 are connected to the fuel accumulator chamber 3, and a plurality of fuel injection valves 5 attached to the internal combustion engine are connected to each fuel supply passage 4. When the internal combustion engine is, for example, six cylinders and each cylinder is provided with one fuel injection valve 5, the number of fuel supply passages 4 and the number of fuel injection valves 5 are each six.

A fuel pressure sensor 6 is provided in the fuel accumulator 3 so as to detect the fuel pressure in the fuel accumulator 3. Further, the fuel pressure sensor 6 is connected to a control device 7 composed of a computer.

The control device 7 includes an accelerator sensor S1 for detecting whether or not the accelerator pedal is depressed.
An intake pressure sensor S2 for detecting an intake pressure to the internal combustion engine, a water temperature sensor S3 for detecting a temperature of cooling water of the internal combustion engine, an engine speed sensor (NE sensor) S4 for detecting a rotation speed of the internal combustion engine, Aeroflow meter S5 for detecting the amount of air intake, G sensor S6 for identifying the stroke of each cylinder
In addition, various sensors necessary for vehicle control are connected.

The control device 7 is provided with a fuel pump drive control unit 8 and a fuel injection valve drive control unit 9 which operate according to operating conditions determined based on information from the various sensors. 2 and the fuel injection valve 5 are drive-controlled.

The controller 7 performs feedback control of the fuel pressure in the fuel accumulator 3 so as to reach a preset target pressure for steady operation. That is, the fuel pressure sensor 6
Until the detected pressure reaches the target pressure, a drive signal for fuel pumping is sent to the fuel pump 2 to continue fuel supply, and when the target pressure is reached, the fuel pumping of the fuel pump 2 is stopped. Repeat the control.

When the pressure in the fuel storage chamber 3 reaches a predetermined set pressure exceeding the target pressure, the pressure in the fuel storage chamber 3 is released. An escape relief valve 11 is provided. The relief valve 11 is provided so as to be interposed in a fuel release path 12 connected to the fuel supply source side, that is, the fuel tank 1. <Fuel Injection Valve> Next, the configuration of the fuel injection valve of the present invention will be described.

As shown in FIG. 2, the fuel injection valve 5 has a cylindrical main body 22 having a fuel injection hole 21 at a tip thereof, and a needle valve 23 as a valve body provided in the main body 22 so as to be movable forward and backward. The needle valve 23 is advanced by the pressure of the high-pressure fuel introduced into the main body 22, the fuel injection hole 21 is closed, and the high-pressure fuel is discharged from the main body 22 to remove the needle valve 23.
And the fuel injection holes 21 are opened.

Further, the fuel injection valve 5 of the present invention has a cylindrical sleeve 25 as an inertial mass body provided separately from the needle valve 23, and a needle valve 23 provided on the outer periphery of the needle valve 23. When the needle valve 23 retreats, the engagement portion 23c that engages with the sleeve 25
The coil spring 2 as urging means for urging the engaging portion 23c and, consequently, the needle valve 23 in the advance direction through the coil spring 2
4 is provided.

The main body 22 has a supply port 31a for receiving the high-pressure fuel supplied at a predetermined pressure from the fuel injection device, and a first fuel supply for guiding the high-pressure fuel from the supply port 31a to the fuel injection hole 21 at the tip. Road 31 and fuel outlet 2
1 and receives the high-pressure fuel introduced from the first fuel supply passage 31 to retreat the needle valve 23 (open).
The fuel chamber 31b presses the high-pressure fuel from the supply port 31a and presses the needle valve 23 in the advance (close) direction, and the control chamber 32 branches from the first fuel supply path 31 to supply the high-pressure fuel. A second fuel supply passage 33 leading to the control chamber 32; a communication chamber 20 communicating the control chamber 32 with the fuel reservoir 31b; and a high-pressure fuel in the control chamber 32 being discharged to reduce the hydraulic pressure in the control chamber 32. And a fuel discharge passage 34 for lowering.

The main body 22 is interposed from the control chamber 32 to the fuel discharge passage 34. When the main body 22 is closed, high-pressure fuel is confined in the control chamber 32. When the main body 22 is open, the fuel escapes from the control chamber 32 to the fuel discharge passage 34. , A normally closed back pressure control valve 35.

The second fuel supply passage 33 has an inlet orifice 33a for determining the amount of fuel flowing into the control chamber 32. The fuel discharge path 34 is
An outlet orifice 34a for determining a fuel discharge amount is provided.

The inlet orifices 33
The outlet orifice 34a is set to be larger than the inlet orifice 33a, for example, the ratio of the passage cross-sectional area of the outlet orifice 34a to 2: 3.

The fuel reservoir 31b and the communication chamber 2
A sub-cylinder chamber 26 is provided so as to communicate with the zero. The control chamber 32, the communication chamber 20, and the sub-cylinder chamber 26 are cylindrical holes. The inner diameter of the hole of the control chamber 32 is formed larger than the inner diameter of the hole of the sub cylinder chamber 26.

At the boundary between the control chamber 32 and the communication chamber 20, there is provided a projection 22a projecting inside the hole, and the tip of the projection 22a has a circular hole shape. Further, at the boundary between the communication chamber 20 and the sub-cylinder chamber 26, a protruding portion 22b protruding inside the hole is provided.
The tip of 2b has a circular hole shape.

The fuel reservoir 31b and the fuel injection hole 2
1 and a nozzle portion 2 for guiding fuel to the fuel injection hole 21.
1a is provided. The nozzle portion 21a is a teardrop-shaped hole, and the hole diameter is formed smaller than the tip diameter of the needle valve 23, so that when the tip of the needle valve 23 advances, the hole of the nozzle portion 21a can be closed and closed. Is formed.

The fuel injection valve 5 employs a hole type injection nozzle, and the needle valve 23 has a conical tip. And the needle valve 23
The control chamber 32, the communication chamber 20, and the fuel reservoir 31 in the main body 22
b so as to be able to move forward and backward freely.

The needle valve 23 faces the control chamber 32, and receives a fuel pressure in the control chamber 32 to advance (close) the needle valve 23, and a sub piston 23a.
A sub-piston 23d that faces the cylinder chamber 26 and the fuel reservoir 31b and retreats (opens) the needle valve 23 by receiving fuel pressure in the fuel reservoir 31b, and between the sub-piston 23d and the main piston 23a. It has a rod portion 23b provided and an engaging portion 23c provided on the outer periphery of the rod portion 23b.

The main piston 23a has a cylindrical shape and is slidable along the side wall of the control chamber 32. The sub piston 23d also has a cylindrical shape, and is formed to be slidable along the side wall of the sub cylinder chamber 26.

When the sub piston 23d receives the high-pressure fuel in the fuel reservoir 31a when the needle valve 23 is closed, the pressure receiving area Ss is determined by the main piston 23a,
2 is smaller than the pressure receiving area Sm for receiving the high-pressure fuel (Ss
<Sm) is set.

The rod portion 23b has a cylindrical shape with a smaller diameter than the main piston 23a and the sub piston 23d, and can move forward and backward in the communication chamber 20. In the communication chamber 20, the coil spring 24 and the sleeve 25 are arranged around the rod portion 23b, and the sleeve is slidable around the rod portion 23b in the axial direction.

The coil spring 24 is inserted into the rod 23b. One end of the coil spring 24 is engaged with the convex portion 22 a interposed between the control chamber 32 and the communication chamber 20, and the other end is engaged with the sleeve 25, and moves the sleeve 25 in the forward (valve closing) direction. It is energizing.

The main piston 23a is connected to the control room 3
When the pressing force received from the fuel pressure in the fuel tank 2 is Fm, the pressing force received by the sub-piston 23d from the fuel pressure in the fuel reservoir 31b is Fs, and the urging force of the coil spring 24 is Fc, when the valve is closed, Fm + Fc> Fs, Fc <Fs.
The urging force of the coil spring 24 is
3 retreats, the engaging body 23c is inserted through the sleeve 25.
Is urged in the valve closing direction of the needle valve 23 to reduce the retreat speed of the needle valve 23 retreating integrally with the sleeve 25 together with the sleeve 25,
Further, when the needle valve 23 advances, the urging force is such that the sleeve 25 and the engagement portion 23c are advanced separately.

The engaging portion 23c is connected to the rod portion 23b
The needle valve 23 is engaged with one end of the sleeve 25 when the needle valve 23 retreats. In addition, sleeve 2
The other end of 5 is engaged with the coil spring 24 and is urged in the forward (closed) direction.

The fuel injection hole 21 is provided in the nozzle 21
Several are radially opened at a certain angle (ejection angle) with respect to a. The back pressure control valve 35 is formed of an electromagnetic valve, and is provided in the main body 22. When the back pressure control valve 35 is closed, the fuel pressure applied to the control chamber 32 increases, and the main piston 23a is pushed by the pressure, and the urging force of the spring 24 is also applied thereto. The needle valve 23 descends. <Fuel Injection Valve Drive Control> Next, fuel injection valve drive control will be described. The fuel injector drive control is performed by the fuel injector drive controller 9.

In a diesel engine, fuel injection is performed at a predetermined crank angle of the engine during a compression stroke to an expansion stroke.
For example, a predetermined amount is performed from 10 ° CA (crank angle) before top dead center to 5 ° CA after top dead center. BTDC10 injection start timing
In the case of ° CA (Before top deadcenter 10 crank angle), the fuel injection time is added to this to determine the injection end timing.

Next, the operation of the fuel injection valve 5 of the present invention will be described with reference to FIG.
A description will be given based on the time chart of FIG. First, the time when the needle valve is opened will be described.

When the back pressure control valve 35 is opened by an electromagnetic valve opening command (see FIG. 4A, back pressure control valve drive pulse “up”) of the fuel injection valve drive control unit 9, control is performed from the fuel discharge passage 34. The fuel in the chamber 32 is discharged. At this time, since the outlet orifice 34a is set to be larger than the inlet orifice 33a, the amount of charge (replenishment) flowing into the control chamber 32 (see the fuel inflow amount in FIG. 4C) flows out of the control chamber 32. 4 (d), the fuel pressure in the control chamber 32 decreases (see FIG. 4 (b)).

The sum of the pressing force Fm for urging the needle valve 23 in the valve closing direction due to the fuel pressure in the control chamber 32 and the urging force Fc of the coil spring 24 is used as the needle valve 23 due to the fuel pressure in the fuel reservoir 31b. When the pressure becomes smaller than the pressing force Fs (Fm + Fc <Fs) for urging the needle valve 23 in the valve opening direction, the needle valve 23 retreats against the urging force of the coil spring 24, the fuel injection hole 21 is opened, and the fuel injection is started. Be started.

When the needle valve 23 retreats, the engaging portion 23c provided on the outer periphery of the rod portion 23b engages with one end of the sleeve 25 as shown in FIG.
The needle valve 23 and the sleeve 25 retreat together (see the solid line of the needle valve lift in FIG. 4E). Therefore, the mass when the needle valve 23 retreats depends on the rod 2
The sum of the mass M _S of 3b mass M _P and the sleeve 25 (M _P
+ M _S ).

When the needle valve 23 is integrated with the sleeve 25 and retreats against the urging force of the coil spring 24,
At the start of injection, the conventional needle valve is raised (FIG. 4 (e)).
The needle valve 23 retreats more slowly than the needle valve lift (see the broken line of the needle valve lift), and the initial injection rate can be stably suppressed to a low level, thereby suppressing the combustion noise (see the solid line of the fuel injection rate in FIG. 4 (f). The dashed line in FIG. 4 (f) indicates the conventional fuel injection rate).

Next, the operation when the needle valve is closed will be described. The back pressure control valve 3 is in response to a solenoid valve closing command (see FIG. 4 (a) back pressure control valve drive pulse "down") from the fuel injection valve drive control unit 9.
5 is closed, the amount flowing out of the control room 32 (FIG. 4)
While (d) the fuel inflow amount stops, the charge flow rate of the high-pressure fuel from the inlet orifice 33a (FIG. 4C)
The fuel effluent amount is effective, and as a result, the control room 32
The internal fuel pressure increases (see FIG. 4B).

Then, the fuel of the same pressure as that applied to the control chamber 32 is introduced from the first fuel supply passage 31 into the fuel reservoir 31a, and presses the sub-piston 23c. The pressing force Fs becomes Fm + Fc. The needle valve 23 advances (falls) because it cannot be completely withdrawn.

At this time, the rod portion 23b and the engaging portion 23
c descends in synchronization with the main piston 23a, but since the sleeve 25 is separate from the rod part 23b, it does not receive the force in the descending direction due to the pressure imbalance, and the engagement part 23c
Only when the coil spring 24 is separated, the coil spring 24 returns to the initial position (the position when the needle valve is closed). Therefore, the mass when the valve 23 moves forward becomes only the mass M _P of the rod portion 23b, it is possible to advance become nimble, closing speed of the needle valve 23 is conventional (see the broken line in FIG. 4 (e))
(See the solid line in FIG. 4 (e)), and the lack of injection (sharp cut) is improved. <Other Embodiments> Next, a fuel injection valve according to another embodiment of the present invention will be described.

The difference between this alternative embodiment and the above-described embodiment is that when the needle valve retreats, the urging means causes the engagement portion via the sleeve and, consequently, the needle until the needle valve retreats by a predetermined amount. That is, a prohibition means for prohibiting biasing of the valve in the advance direction is added.

First, the configuration of a fuel injection valve according to another embodiment will be described with reference to FIG. Those having the same functions as those of the configuration of the fuel injection valve shown in FIG. 2 are denoted by the same reference numerals in FIG. 5, and the description thereof will be omitted.

The main body 42 is provided at the supply port 3 for receiving the high-pressure fuel supplied at a predetermined pressure from the fuel injection device.
1a, a first fuel supply passage 31 for leading high-pressure fuel from the supply port 31a to the fuel injection hole 21 at the tip, and a high-pressure fuel connected to the fuel ejection hole 21 and introduced from the first fuel supply passage 31. A fuel reservoir 31b for pressing the needle valve 43 in a backward (opening) direction, a control chamber 32 for receiving high-pressure fuel from the supply port 31a and pressing the needle valve 43 in an advancing (closed) direction; A second fuel supply path 3 that branches off from the path 31 and guides the high-pressure fuel to the control chamber 32
3, a communication chamber 40 for communicating the control chamber 32 with the fuel reservoir 31b, and a control chamber 3 for discharging high-pressure fuel in the control chamber 32.
And a fuel discharge passage 34 for lowering the fluid pressure in the fuel cell 2.

The fuel reservoir 31b and the communication chamber 40
And a sub-cylinder chamber 46 is provided. The control chamber 32 and the sub-cylinder chamber 46 are cylindrical holes, and the inner diameter of the control chamber 32 is larger than the inner diameter of the sub-cylinder chamber 46.

At the boundary between the control chamber 32 and the communication chamber 40, there is provided a convex portion 42a projecting inside the hole, and the tip of the convex portion 42a has a circular hole shape. Also,
At the boundary between the communication chamber 40 and the sub-cylinder chamber 46, there is provided a projection 42b projecting into the inside of the hole.
Has a circular hole shape.

The needle valve 43 is interposed between the control chamber 32, the communication chamber 40, the sub-cylinder chamber 46, and the fuel reservoir 31b in the main body 42 so as to be movable forward and backward.
In addition, the needle valve 43 faces the control room 32 and the control room 3
The needle valve 43 advances (closes) in response to the fuel pressure in 2
Main piston 43a and sub-cylinder chamber 4
6 and a sub-piston 43d which faces the fuel reservoir 31b and retreats (opens) the needle valve 43 by receiving fuel pressure in the fuel reservoir 31b, and is provided between the sub-piston 43d and the main piston 43a. Rod part 4
3b and an engaging portion 43c provided on the outer periphery of the rod portion 43b.

The main piston 43a has a cylindrical shape and slides along the side wall of the control chamber 32. The sub piston 43d also has a cylindrical shape, and slides along the side wall of the sub cylinder chamber 46.

The pressure receiving area Ss in which the sub piston 43d receives the high-pressure fuel in the fuel reservoir 31a is set smaller than the pressure receiving area Sm in which the main piston 43a receives the high-pressure fuel in the control chamber 32 (Ss <Sm). Have been.

The rod portion 43b has a cylindrical shape with a smaller diameter than the main piston 43a and the sub piston 43d, and can move forward and backward in the communication chamber 40. In the communication chamber 40, the urging means 24a and the sleeve 45 are disposed around the rod 43b.

The urging means 24a is, for example, a coil spring. This coil spring 24a
It is inserted into the rod part 43b. One end of the coil spring 24a is engaged with the convex portion 42a interposed between the control chamber 32 and the communication chamber 40, and the other end is engaged with the sleeve 45, so that the sleeve 45 is moved in the advance (valve closing) direction. It is energizing.

The main piston 43a is connected to the control room 3
Fm, the pressing force received by the sub piston 43d from the fuel pressure in the fuel reservoir 31b is Fs, and the urging force of the coil spring 24a is Fc. In a steady state, Fm + Fc> Fs , Fc <Fs. Further, the urging force of the coil spring 24a is such that when the needle valve 43 retreats, the engagement body 43c is urged via the sleeve 45 to the side where the needle valve 43 advances, and the retraction speed of the needle valve 43 is delayed. And the urging force is such that the sleeve 45 and the engaging portion 43c are advanced separately when the needle valve 43 advances.

The sleeve 45 is, for example, a stepped cylindrical sleeve having a flange 45a at one end, and is slidably inserted into the rod 43b. The engaging portion 43c is provided in a flange shape on the outer periphery of the rod portion 43b, and engages with one end of the flange portion 45a of the sleeve 45 when the needle valve 43 retreats. The other end of the sleeve 45 is engaged with the coil spring 24 and is urged in the forward (closed) direction.

The communication chamber 40 has a stepped hole 40 a having a diameter larger than the inner diameter of the communication chamber 40. The inner diameter of the stepped hole 40a is slightly larger than the outer diameter of the flange 45a of the sleeve 45, and is formed so that the flange 45a of the sleeve 45 can be stored.

The width of the stepped hole 40a is such that the flange 45a of the sleeve 45 can move from the upper end to the lower end of the stepped hole 40a with a stroke of St3. Also,
The position where the stepped hole 40a is formed in the communication chamber 40 is a position where the size from the upper surface of the engaging portion 43c to the lower end of the stepped hole 40a becomes St1 when the needle valve 43 is closed.

Therefore, the prohibition means includes a flange 45 at one end thereof.
a sleeve 45 provided with a flange 45a, a stepped hole 40b in which the flange 45a can be moved and stored with a stroke of St3, and a surface which engages with the flange 45a when the needle valve 43 is closed. The St1 dimension is provided from the lower end of the stroke, and the St1 dimension is provided with an engaging portion 43c provided at a position smaller than the stroke St3 (St1 <St3).

Assuming that the maximum (Max.) Regression amount of the needle valve 43 (that is, the sub piston 43d) is Stmax., As shown in the needle valve lift of FIG.
max. = St1 + St2. The restriction on the stroke St3 shown in FIG.
That is, the stroke St3 is larger than the stroke St2 that moves by urging (St3> St2).

Next, the operation of this embodiment will be described with reference to the time chart of FIG. The difference from the operation of the above-described embodiment is that when the needle valve retreats, the prohibiting means engages the urging means 24a via the sleeve 45 with the protruding side until the needle valve retreats by the dimension St1. That is, the portion 43c is not biased in the valve closing direction of the needle valve 43. Therefore, the description will be made only when the needle valve is opened, and the description when the needle valve is closed will be omitted.

In response to the solenoid valve opening command from the fuel injection valve drive control unit 9, when the needle valve 23 retreats, the flange 45a of the sleeve 45 until the engagement part 43c retreats by the dimension St1.
Does not engage with Therefore, during the initial injection, the needle valve 43
Since there is only the mass M _P of the rod portion 43b when regressing by the dimension St1, it is possible to retreat steeply (FIG. 6E).
St1).

Next, when the needle valve 23 further retreats beyond the dimension St1, the engaging portion 43c engages with the flange 45a of the sleeve 45, and thereafter, the needle valve 23 and the sleeve 45 retreat integrally. . Therefore, the mass at that time is
It is the sum of the mass M _P of the rod 43b and the mass M _{S of the} sleeve 45 (M _P + M _S ). When the needle valve 43 is integrated with the sleeve 45 and retreats against the urging force of the coil spring 24, as described in the operation of the first embodiment, the conventional needle valve is raised (FIG. 6 (e)). )
The needle valve 43 retreats more gently (see the broken line of the needle valve lift).

As described above, in another embodiment, the provision of the prohibition means allows the needle valve 43 to be used during the initial injection.
Is a two-stage regression. Since the regression of the needle valve 43 is performed in two stages, the initial injection rate can be freely selected as compared with the conventional case (see the solid line of the fuel injection rate in FIG. 6F, and the broken line in FIG. 6F). Indicates the conventional fuel injection rate).

Further, for example, by setting the urging force of the coil spring 24a to be equal to or higher than the urging force at which the sleeve 45 follows the moving speed of the needle valve 43 when the needle valve 43 advances (closes), the needle valve 43 indicates that the regression amount St is St1 <St <St.max (= St1 + St2,
6 (e), the coil spring 24a advances (closes the valve) via the sleeve 45.
Since the urging force acts on the side, the needle valve closing speed is high, and a sharp cut can be achieved.

In another embodiment, as described above, the fuel injection rate can be stably suppressed at the initial stage, so that the combustion noise can be reduced, the NOx can be reduced, and the excessive increase in the cylinder pressure due to excessive fuel injection can be prevented. In addition to suppressing the exhaust emission, the sharp cut at the time of closing the needle makes it possible to improve the injection cut-off, thereby suppressing the deterioration of the exhaust emission.

In another embodiment, the needle valve 4
Due to the temporary decrease in the regression acceleration of the needle valve 43 due to the engagement of the sleeve 3 with the sleeve 45, even if the fuel injection rate is initially suppressed low, the fuel injection rate can be raised as steeply as before. So that the injection period can be shortened,
Full load performance is improved.

Further, if the injection periods are made equal, the injection hole area of the fuel injection holes can be reduced, and PM can be reduced.

[0084]

According to the present invention, when the valve body retreats (opens), the valve body and the inertial mass body retreat integrally while the retraction speed of the valve body is delayed by the urging means. Therefore, at the start of the injection, the valve body slowly retreats (opens), and the initial injection rate can be suppressed to be low, and the combustion noise can be suppressed. On the other hand, when the valve body advances (closes), the valve body and the inertial mass body advance separately, so that at the end of injection, the valve body advances (closes valve) quickly and the injection is stopped properly. As a result, deterioration of the emission can be suppressed.

Further, since the above function is realized only by a simple structure in which the inertial mass body is separately provided on the valve body, there is an advantage that it can be provided at a low cost. Further, the present invention does not depend on the control of the pressure of the supplied fuel itself, but rather mechanically causes the valve body to gently retreat (open) or to advance (close) quickly by the inertial mass body. Valve), the initial injection rate can be stably suppressed to a low level without being affected by the operating state or fuel itself, and combustion noise can be suppressed. At the end of injection, the valve body advances (closes) immediately. Valve) to improve the cut-off of injection and suppress deterioration of emission.

Further, since the urging force in the valve closing direction is applied to the valve element in a stepwise manner by the prohibiting means having the above structure, two-stage injection can be performed.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a fuel injection device according to the present invention.

FIG. 2 is a configuration diagram of a fuel injection valve according to the embodiment;

FIG. 3 is an explanatory diagram when a valve body of a fuel injection valve retreats.

FIG. 4 is a timing chart showing injection characteristics of the embodiment.

FIG. 5 is a configuration diagram of a fuel injection valve according to another embodiment.

FIG. 6 is a timing chart showing injection characteristics of another embodiment.

FIG. 7 is a detailed view showing the vicinity of a fuel injection hole.

FIG. 8 is an explanatory diagram of fuel injection characteristics of a conventional device.

[Explanation of symbols]

 1. Fuel tank as fuel supply source 2. Fuel pump 3. Fuel accumulator chamber 4. Fuel supply path 5. Fuel injection valve 6. Fuel pressure sensor 7. Control device 8. Fuel pump drive Control unit 9 Fuel injection valve drive control unit 11 Relief valve 12 Fuel release path 20 Communication chamber 21 Fuel injection hole 21a Nozzle unit 22 Main unit 22a Projecting unit 22b Convex part 23 ·· Valve (needle valve) 23a ··· Main piston 23b ··· Rod part 23c ··· Engaging part 23d ··· Sub piston 24 ··· Coil spring 25 ··· Inertial mass body (sleeve) 26 · · Sub-cylinder chamber 31 ··· First fuel supply path 31a ··· Supply port 31b ··· Fuel reservoir 32 ··· Control room 33 ··· Second fuel supply path 33a ··· Inlet orifice (fuel inlet) 34.・ Fire Charge discharge path 34a Outlet orifice 35 Back pressure control valve 40 Communication chamber 40a Stepped hole 42 Main body 42a Convex part 42b Convex part 43 Valve element (needle valve) 43a ··· Main piston 43b ··· Rod part 43c ··· Engaging part 43d · · · Sub piston 24a · · · Coil spring 45 · · · Inertia mass body (sleeve) 45a · · · Flange part 46 · · · Sub cylinder chamber 50・ Fuel injection valve

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 61/16 F02M 61/16 X

Claims (2)

[Claims] 1. A main body having a fuel injection hole at a tip thereof, and a valve body provided movably forward and backward inside the main body, wherein the valve body is advanced by the pressure of high-pressure fuel introduced into the main body. A fuel injection valve that closes the fuel injection hole, discharges high-pressure fuel from within the main body and retreats the valve body to open the fuel injection hole, wherein an inertial mass body provided separately from the valve body An engaging portion provided on the valve body and engaging with the inertial mass body when the valve body retreats; and when the valve body retreats, engages with the engaging portion and retreats together with the valve body. A biasing means for biasing the valve body in the advance direction via an inertial mass body. 2. The fuel injection valve according to claim 1, further comprising a prohibition means for prohibiting the urging of the urging means until the valve element retreats by a predetermined amount when the valve element retreats. .