ES2231365T3 - FUEL INJECTOR. - Google Patents

Abstract

Fuel injector (1) comprising: a housing (2) with a nozzle (4); a needle (3) mobilely housed in a needle housing chamber (5), formed in the housing (2), to open or close the nozzle (4); a pressure control chamber (8) defined between the needle (3) and an inner wall of the needle housing chamber (5) and filled with a fuel, depending on the displacement of the needle (3) from the pressure of the fuel in the pressure control chamber (8); a pressure control valve (14) mobilely provided in the housing (2) to control the fuel pressure in the pressure control chamber (8); and an actuator (15) for controlling the displacement of the pressure control valve (14); where needle (3) is displaced in a first displacement when the pressure control valve (14) is moved to the zero position, where the needle (3) is displaced in a second displacement when the control valve (14) of the pressure is moved to the fully displaced position, where the needle (3) is displaced in a third displacement when the pressure control valve (14) is moved to an intermediate position between the zero position and the fully displaced position, where the third displacement is between the first and the second displacement, where the needle (3) closes the nozzle (4) when it is displaced in the first displacement, in which the needle (3) partially opens the nozzle (4) when it is displaced in the third displacement, and where the needle (3) fully opens the nozzle (4) when it is displaced in the second displacement; where a displacement control piston (9) is mobilely housed in the pressure control chamber (8), the displacement control piston (9) dividing the pressure control chamber (8) into chambers ( 8a, 8b) of the first and second pressure control, the first pressure control chamber (8a) being defined between the displacement control piston (9) and the needle (3), and the second chamber ( 8b) of pressure control between the piston (9) of displacement control and the inner wall of the needle housing chamber (5), where the valve chamber (10), filled with fuel, is formed in the housing (2) for housing the pressure control valve (14), where a source of high fuel pressure is connected to the second pressure control chamber (8b) and to the chamber (10) of the valve through ducts (20b, 20c) second and third flow inlet, respectively The first and second chambers (8a, 8b) of pressure control are connected to the chamber (10) of the valve through the first and second flow inlets (20a, 20b), respectively, and where the pressure control valve (14) controls a connection between the valve chamber (10) and a drain line (12) and a connection (19) between the valve chamber (10) and the pressure source high fuel

Description

Fuel injector.

Fundamentals of the invention 1. Scope of the invention

The present invention relates to an injector of fuel as well as a method of fuel injection.

2. Description of the related technique

The publication of the Japanese Patent Without Examine, number 8-334072, reveals an injector of fuel, which has a housing with a nozzle, a needle housed movably in a needle housing chamber formed in the housing, and a control valve to control a displacement of the needle. In this fuel injector, the control valve it is displaced by the pressure applied to the fuel injector, and is moved to a zero position when the fuel pressure is low, to a fully displaced position when the pressure of the fuel is high, and at an intermediate position, between zero and totally displaced, when the fuel pressure is half.

The needle can move completely when the control valve moves to zero position or to a position fully displaced, and can be partially displaced when the control valve is moved to the intermediate position.

However, during the displacement of the control valve from zero position to displaced position totally, the control valve must pass through the position intermediate, in which the displacement of the needle is limited. This can prevent rapid needle movement to open the nozzle completely.

WO 99 15 779 A discloses a valve of injection. To control a needle, two perforations are used connected to a low pressure liquid source and a perforation connected to a high pressure liquid source.

Summary of the invention

The object of the invention is to provide an injector of fuel and a method of fuel injection to make fast needle movement possible.

The above object is resolved, with respect to the fuel injector, by means of the features of claim 1 and, with respect to the method, with the features of claim 8. Further developments are the subject of the other claims.
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Brief description of the drawings

In the drawings:

Figure 1 is an overview of an injector of fuel according to the present invention;

Figure 2 is an enlarged view of part A of figure 1;

Figure 3 is a partially enlarged view of the Fuel injector;

Figure 4 is an enlarged view, similar to that of Figure 2, to explain an operation of an injector of fuel shown in figure 1:

Figure 5 is an enlarged view, similar to that of Figure 2, to explain an operation of an injector of fuel shown in figure 1;

Figs. 6 to 11 show various embodiments of the fuel injection; Y

Figure 12 is an enlarged view, similar to that of Figure 2, illustrating another embodiment according to the present invention.

Description of preferred embodiments

In relation to figures 1 to 3, an injector 1 of fuel comprises a housing 2 and a needle 3. The housing 2 includes a nozzle holder 2a with a pair of nozzles 4, a body 2b coating, a 2c actuator coating, and about 2d, 2e, 2f, 2g and 2h camera defining elements. Needle 3 includes a needle body 3a and a series of piston elements 3b, and is housed in a needle housing chamber 5, formed in the housing 2, movably along its longitudinal axis. The needle 3 is displaced to open or close the nozzles 4.

A fuel supply conduit 6 is formed in the housing 2 from a fuel inlet 7 formed in the housing 2 to the nozzles 4. The fuel inlet 7 is connected to a high pressure fuel source, such as a pump (not shown) with common manifold with a pressure of constant fuel

A pressure control chamber 8 is defined between the upper end of the needle 3 and the inner wall of the needle housing chamber 5. In the control chamber 8 of the pressure, a piston 9 of displacement control is housed axial and mobile to divide the pressure control chamber 8 into First and second pressure control chambers 8a and 8b. The first pressure control chamber 8a is defined between the lower end of the displacement control piston 9 and the upper end of the needle 3, and the second control chamber 8b of the pressure is defined between the upper end of the piston 9 of displacement control and inner wall of chamber 5 of needle housing.

The displacement control piston 9 includes an annular flange 9a, which limits a downward movement of the piston 9 together with an annular flange 5a formed in the chamber 5 of needle housing. Note that a shift towards above the piston 9 is limited by the contact between the end upper piston 9 and upper end wall of chamber 5 of needle housing.

A valve chamber 10 has also been formed in the housing 2, which is connected to the control chamber 8 of the pressure through a discharge duct. Specifically, the chamber 10 of the valve is connected to the first chamber 8a of pressure control through a first conduit 11a of discharge, and is connected to the second control chamber 8b of the pressure through a second discharge conduit 11b.

As described below, cameras 8a and 8b pressure control and valve chamber 10 are refilled with fuel

Drainage channels 12, formed in the housing 2, extend from chamber 10 of the valve to outlet 13 of the fuel, formed in the housing 2. The outlet 13 of fuel may be connected to a fuel tank (no shown).

A pressure control valve 14 is mobilely housed in the valve chamber 10 along of its longitudinal axis. The pressure control valve 14 includes a spherical element 14a and an element 14b in the form of rod, which are an integral part of each other.

The pressure control valve 14 is moved by an actuator 15, of a piezoelectronic type, housed in the housing 2. The actuator 15 controls the axial displacement of the pressure control valve 14 by means of a control of a fuel pressure in a chamber 16 filled with fuel, between actuator 15 and pressure control valve 14. Specifically, when the actuator lengthens along its axis longitudinally, the fuel pressure in chamber 16 increases and, in this way, the pressure control valve 14 moves down. When the actuator contracts along its axis longitudinally, the pressure in the chamber 16 decreases and, thus, the pressure control valve 14 moves up.

The fuel supply conduit 6 includes a fuel collection chamber 17, formed within the same, in which a receiving surface 3c of the pressure, formed in the needle. Therefore, needle 3 is requested, by the fuel pressure of the collection chamber 17 of fuel, in a direction in which the needle 3 opens the nozzles 4. Needle 3 is also requested by a spring 18 of compression, arranged between the needle 3 and the inner wall of the needle housing chamber 5, in a direction in which the needle 3 closes the nozzles 4.

A high fuel pressure line 19 separates from the fuel supply line 6 and connects with the first and second chambers 8a and 8b of pressure control a through conduits 20a and 20b of incoming flow first and second, respectively. The high fuel line 19 pressure is also connected to the valve chamber 10 through of a third conduit 20c of incoming flow.

Note that, in the present embodiment, the first and second discharge ducts 11a and 11b and the ducts 20, 20b, 20c of incoming flow first, second and third include diffusers formed within them.

The current resistance of the second incoming flow duct 20b is regulated less than that of the first incoming flow duct 20a, and the current resistance of the second discharge duct 11b is regulated greater than that of the first discharge duct 11a. Crushing is also applied hydroerosive only in one direction from the valve chamber 10 to the pressure control chamber 8b, such that it set a lower discharge coefficient of the second duct 11b discharge, in one direction from the second control chamber 8b of the pressure to the valve chamber 10, than that of one direction from the valve chamber 10 to the control chamber 8b of the Pressure. Therefore, the pressure of the second control chamber 8b of the pressure is easily increased, but it is difficult to reduce, with with respect to the pressure of the first control chamber 8a of the Pressure.

Figure 2 shows the case in which the valve Pressure control 14 is in a zero position. In this position, the pressure control valve 14 prevents communication between the valve chamber 10 and the ducts 12 of drain, and connect the valve chamber 10 with the conduit 19 of high fuel pressure Under these conditions, the fuel of the high pressure fuel line 19 flows to the chamber 8a of pressure control through the first inlet duct 20a of flow, and through the third flow inlet conduit 20c, the valve chamber 10 and the first discharge duct 11a. Also, fuel flows to the second control chamber 8b of pressure through the second flow inlet conduit 20b, and a through the third flow inlet duct 20c, the chamber 10 of the valve and the second discharge duct 11b.

This increases the fuel pressure in the second pressure control chamber 8b and maintains the piston 9 of displacement control in its lowest position, where its flange 9a makes contact with the flange 5a of the housing chamber 5 of the needle. Also, this increases the fuel pressure in the First pressure control chamber 8a. Therefore, a force towards below, which acts on the needle 3 to close the nozzles 4, and that it is provided by the fuel pressure in chambers 8a and 8b for controlling the pressure and applied force of the spring 18, exceeds an upward force acting on the needle to open the nozzles 4, which is provided by the fuel pressure in chamber 17 fuel collector. Therefore, the needle 3 close the nozzles 4.

Note that, under these conditions, the part upper of the needle 3 and the bottom of the control piston 9 of the displacement are separated from each other by a distance D1, and the upper part of the piston 9 and the upper part of the inner wall of the needle housing chamber 5 are separated from each other for a distance D2, as shown in Figure 3.

Figure 4 shows the case in which the valve pressure control is in an intermediate position or is displaced a small SD offset from the zero position. In this position, pressure control valve 14 connects partially the valve chamber 10 with the ducts 12 of drain, and connect the valve chamber 10 with the conduit 19 of high pressure fuel. Under these conditions, the fuel flows to the first pressure control chamber 8a through the first flow inlet duct 20a. However, the fuel of the first pressure control chamber 8a exits it through of the first discharge duct 11a and the valve chamber 10 towards the discharge ducts 12. Therefore, the pressure drops of the first pressure control chamber 8a. As a consequence of this, the upward force, acting on the needle, exceeds the downward force acting on the needle 3 and thus the needle is displaced up.

Moreover, at this moment, the fuel flows to the second pressure control chamber 8b through the second flow inlet conduit 20b and the second conduit 11b Download Note that, in the present embodiment, the magnitudes of the opening formed between the valve chamber 10 and the drainage ducts 12 and the resistance to the current of the ducts 11a, 11b, 20a and 20b are established in such a way that the fuel flows from the valve chamber 10 to the second pressure control chamber 8b, even if chamber 10 of the valve is connected to drainage pipes 12. Therefore, the pressure of the second pressure control chamber 8b is maintained high, and thus the displacement control piston 9 is maintained in The lowest position.

The upward movement of the needle 3 is limited by a stop of the needle 3 with the control piston 9 of the displacement, as shown in figure 5. Thus, the needle 3 moves D1 or partially opens the nozzles 4 by the small displacement of the control valve 14 of the Pressure.

Figure 5 shows the case in which the valve 14 pressure control is in a fully displaced position or a total FD offset is moved from the zero position. In that position, the pressure control valve 14 connects the chamber 10 of the valve with drain lines 12, and prevents communication between the valve chamber 10 and the conduit 19 of high pressure fuel. Under these conditions, the pressure of the first 8a pressure control chamber is kept low because the fuel from the first pressure control chamber 8a comes out from it through the first discharge duct 11a and the chamber 10 from the valve to the drainage pipes 12.

At this moment, the fuel of the second pressure control chamber 8b also leaves it through the second discharge duct 11b and the valve chamber 10 towards the drainage pipes 12. Therefore, the fuel pressure of the second pressure control chamber 8b also descends.

As a result, the control piston 9 of the scroll moves up until it makes contact with the inner wall of the needle housing chamber 5 and it keeps in that highest position. The needle 3 also moves until it makes contact with the control piston 9 of the displacement. Consequently, needle 3 is displaced D2 from the condition shown in figure 4 or fully open the nozzles 4, by the total displacement of the control valve 14 of the Pressure.

Figures 6 to 11 show various embodiments of fuel injection.

In the embodiment shown in Figure 6, the VD displacement of pressure control valve 14 is made equal to the small FD offset and remains temporarily in the same, and then it becomes equal to the total FD offset and it temporarily kept in it. Then, the VD displacement of the valve to zero.

As a result, the ND offset of the needle is first made equal to displacement D1 and is maintained temporarily in it, and thus the injection of fuel with a fuel injection FIR quota which is a low RL fee. The needle displacement ND is then increased to D1 + D2, and thus fuel injection is performed with a fee Fuel injection FIR which is a high RH fee.

If the fuel injection starts with the high injection rate RH, the amount of NO_ {x} generated and the Combustion noise may increase. Fuel injection shown in figure 6 starts with the low injection rate RL and, therefore, the generation of NO_ {x} and the noise of combustion.

In the embodiment shown in Figure 7, the VD displacement of the valve is continuously increased from the zero position to fully displaced position, remains in the total FD offset for a preset time. Then he VD displacement of the valve is returned to zero.

A displacement percentage of the pressure control valve 14 so that the displacement ND of the needle is first made equal to displacement D1 and retained temporarily in it, and then the ND offset is increased from the needle to D1 + D2, as in the embodiment shown in the figure 6.

As a consequence, it is carried out first fuel injection with an injection FIR quota of fuel which is the low RL quota, and then the fuel injection with the FIR injection quota of fuel that is the high RH quota.

As described above, the pressure of the second pressure control chamber 8b is easily increased, but it is hardly reduced with respect to the pressure of the first 8a pressure control chamber. Therefore, even if the VD offset of the valve is less than SD offset small, needle 3 begins the upward movement when the upward force, acting on the needle 3, exceeds the force down, which acts on the needle 3. Also, even if the VD displacement of the valve is greater than the SD displacement small, the ND displacement of the needle remains in the displacement D1 while the control piston 9 of the displacement remains in its lowest position. This means that precise control of the displacement of the pressure control valve 14 in order to move the needle 3 the displacement D1.

In addition, the fact that the pressure in the second Pressure control chamber 8b can be easily increased, but it is hardly reduced, it will promote a rapid movement of the needle 3 to close the nozzles 3.

Figure 8 shows a fuel injection of low quota, in which the displacement VD of the valve 14 of pressure control is made equal to the small SD offset and It is temporarily kept in it, and then returned to zero. As a consequence, the ND displacement of the needle is made equal to displacement D1, and is temporarily maintained therein, and fuel injection is performed with the low LR fee. The low fee injection provides a jet of fuel that It has a low penetration force.

As shown in Figure 9, the VD displacement of the valve can be temporarily maintained in a shift greater than the small SD offset and then It can be temporarily kept in small SD offset, when the low-rate fuel injection has to be performed. This promotes rapid displacement of the needle 3 to open the nozzles

Figure 10 shows a fuel injection of high quota, in which the displacement VD of the valve 14 of pressure control is equal to the total FD displacement and is temporarily kept in it, and then returned to zero. How as a result, the ND displacement of the needle becomes the same to displacement D1 + D2 and temporarily stays in it, and it performs the fuel injection with the high RH quota. The high quota injection provides a jet of fuel, which It has a high penetration force.

Figure 11 shows an embodiment of fuel injections made in a combustion cycle of an engine, including a main fuel injection and additional fuel injections, which are performed in addition to the main fuel injection. M fuel injection main in the form of high-share injection can be performed around the top dead center of the intake race of the engine.

Two additional injections are made before The main fuel injection. Specifically, it takes perform an additional first A1 injection in the form of an injection of low fee in the admission race, and then a second is done additional A2 injection in the form of high-dose injection at end of the compression stroke.

The first additional A1 injection in the form of low fee injection serves to form a mixture of air and fuel that is diffused through the combustion chamber while prevents adhesion of additional fuel to the wall of the cylinder. The second additional A2 injection in the form of an injection of high quota serves to place additional fuel near the fuel injected by injection M of main fuel to thereby suppress the generation of smoke.

After fuel injection M main, two additional injections are made. Specifically, an additional third A3 injection is performed in form of injection of high quota at the top of the power stroke, and then a fourth A4 injection is performed in form of injection of low quota in the drive stroke or of escape.

The third additional A3 injection in the form of high quota injection serves to expand the mixing of the mixture of air and fuel in the combustion chamber. The fourth additional A4 injection in the form of low-fee injection serves to supply a reducing agent to a provided catalyst in the exhaust duct to reduce NO_ {x} while avoid additional fuel adhesion on the wall of the cylinder.

Note that in injections A2, A3 second and third additional shown in figure 11, the valve 14 of Pressure control is held in the fully position displaced for a very short time interval. By consequently, the displacement ND of the needle does not reach D1 + D2 and the fuel injection quota does not reach the RH quota high.

Figure 12 shows another embodiment of the fuel injection, in which the first one has been suppressed Inlet flow duct 20a. In this case, the fuel flows to the first pressure control chamber 8a through the first discharge duct 11a.

In the embodiments described above, the needle displacement increases when displacement increases from valvule. In other words, when the control valve 14 of the pressure moves from the zero position to the position fully displaced, the valve is prevented from being displaced first to its fully displaced position and then to its position intermediate. Consequently, a rapid displacement of the needle 3.

In addition, in the above embodiments, with the in order to control a displacement of the needle 3 or a quota of fuel injection, it is only required to control the pressures in the first and second chambers 8a and 8b of control of the pressure, and it is unnecessary to directly push the needle 3 or check the pressure supplied to the fuel injector 1. In addition, the actuator 15 is connected to the control valve 14 of the pressure through the chamber 16 filled with fuel and, by this does not require precise control of a displacement of the actuator 15. Even if actuator 15 lengthens or contracts undesirably according to its temperature, an unwanted change is avoided of the pressures in the first and second control chambers 8a and 8b of pressure.

In addition, in the previous embodiments, the fuel is supplied to the fuel injector 1 at a constant fuel pressure. However, if a pump fuel that supplies the fuel to the injector 1 out of a type driven by the engine, the fuel pressure supplied the fuel injector 1 may vary according to the conditions of engine operation In this case, if the pressure of the fuel becomes high, a quantity of fuel really injected will become large, and, if the pressure of the fuel is low, the amount of fuel really injected will become small.

In order to avoid it, the injection of fee low can be carried out when the fuel pressure is higher than an upper threshold, and high injection rate is carried out when the fuel pressure is lower than a lower threshold. This avoids excess or lack of fuel. supplied to the engine. Also, when the fuel pressure is high, it is unnecessary to discharge a part of the fuel in the fuel injector 1 to reduce the amount of fuel really injected.

In order to judge whether the pressure of the fuel is higher than the upper threshold or is lower than the lower threshold, a pressure sensor can be provided in the common manifold pump. Alternatively, you can judge based on engine operating conditions. Specifically, the fuel pressure will become high during a rapid deceleration, just after an operation of intense engine effort.

In the above embodiments, needle 3 closes the nozzles 4 when the pressure control valve 14 is in the zero position, partially opens the nozzles 4 when the valve 14 is in the intermediate position, and fully opens the nozzles 4 when valve 14 is in the fully displaced position. Alternatively, the needle 3 closes the nozzles 4 when the valve 14 is in the fully displaced position, partially opens the nozzles 4 when the valve 14 is in the intermediate position, and fully open the nozzles 4 when the valve 14 is in the zero position

In addition, the embodiments described above include the displacement control piston 9 arranged in the pressure control chamber 8. Alternatively, you can suppress piston 9 to provide a single control chamber of pressure, a single incoming flow duct and a single discharge duct

According to the present invention, it is possible provide a fuel injector that is capable of displacing Quickly the needle.

A fuel injector comprising a housing with a needle, a needle mobilely housed in a needle housing chamber formed in the housing, to open or close the nozzle, a defined pressure control chamber between the needle and the inner wall of the housing chamber of the needle and refill of fuel, depending on the displacement of the fuel pressure needle in the control chamber of the Pressure; a pressure control valve provided in a manner mobile in the housing to control the fuel pressure in the pressure control chamber; and an actuator to control a displacement of the pressure control valve. The needle is moves to a position, where the nozzle closes when the pressure control valve is moved to zero position, it is moved to a position where the nozzle partially opens when the pressure control valve is moved to a Intermediate position; and is moved to a position, in which it opens totally the nozzle when the pressure control valve is displaced to a fully displaced position.

Claims (15)

1. Fuel injector (1) comprising: a housing (2) with a nozzle (4); a needle (3) mobilely housed in a needle housing chamber (5), formed in the housing (2), to open or close the nozzle (4); a camera (8) of defined pressure control between the needle (3) and a wall inside the needle housing chamber (5) and filled with a fuel, depending on the displacement of the needle (3) of the fuel pressure in the pressure control chamber (8); a pressure control valve (14) mobilely provided in the housing (2) to control the fuel pressure in the pressure control chamber (8); and an actuator (15) for control the displacement of the control valve (14) of the Pressure; where needle (3) is displaced in a first displacement when the pressure control valve (14) is moved to the zero position, where the needle (3) is displaced in a second displacement when the pressure control valve (14) is displaced to the fully displaced position, where the needle (3) is displaced in a third displacement when the valve (14) of pressure control is shifted to an intermediate position between the zero position and the fully displaced position, where the third shift is between the first and the second displacement, where the needle (3) closes the nozzle (4) when it is displaced in the first displacement, in which the needle (3) opens partially the nozzle (4) when it is displaced in the third displacement, and where the needle (3) fully opens the nozzle (4) when it is displaced in the second displacement; where a piston (9) displacement control is mobilely housed in the pressure control chamber (8), dividing the piston (9) of displacement control the pressure control chamber (8) in First and second pressure control chambers (8a, 8b), being defined the first pressure control chamber (8a) between the displacement control piston (9) and needle (3), and being defined the second pressure control chamber (8b) between the displacement control piston (9) and the inner wall of the needle housing chamber (5), where the chamber (10) of the valve, filled with fuel, is formed in the housing (2) to housing in it the pressure control valve (14), where a high fuel pressure source is connected to the second pressure control chamber (8b) and to the chamber (10) of the valve through ducts (20b, 20c) second and third of flow inlet, respectively, and the first being connected and second chambers (8a, 8b) of pressure control to the chamber (10) of the valve through the first and second ducts (20a, 20b) flow inlet, respectively, and where the valve (14) of pressure control controls a connection between the chamber (10) of the valve and a drain line (12) and a connection (19) between the valve chamber (10) and the fuel pressure source high. 2. Fuel injector according to claim 1, wherein the pressure control valve (14) prevents communication between the valve chamber (10) and the drain line (12), and connect the valve chamber (10) to the high fuel pressure source, when displaced to the zero position, where the pressure control valve (14) partially connects the valve chamber (10) to the source of high fuel pressure, when moved to position intermediate, and where the pressure control valve (14) connects the chamber (10) from the valve to the drain line (12) and prevents communication between the valve chamber (10) and the source of high fuel pressure, when moved to position totally displaced 3. Fuel injector according to the claim 1, wherein the first control chamber (8a) of the pressure is connected to the high fuel pressure source through the first flow inlet conduit (20a). 4. Fuel injector according to claim 3, wherein a current resistance of the second flow inlet conduit (20b) is established smaller than the of the first flow inlet conduit (20a). 5. Injector according to claim 1, wherein a resistance to the current of the second conduit (11b) of discharge is established greater than that of the first conduit (11a) of discharge. 6. Fuel injector according to claim 1, wherein a discharge coefficient of the second discharge duct (11b) in the direction from the second bed (8b) pressure control to the chamber (10) of the valve is set lower than the one that goes in the direction from the camera (10) from the valve to the second pressure control chamber (8b). 7. Fuel injector according to claim 1, wherein the fuel pressure source elevated comprises a fuel supply conduit (6), which extends from the housing (2) to the nozzle (4). 8. Fuel injection method with a fuel injector according to one of claims 1 to 7, in which the pressure control valve (14) is displaced to the intermediate position, and temporarily held therein, so that the needle (3) temporarily open the nozzle (4) partially, and be then moved to the fully displaced position, so that the needle (3) fully open the nozzle (4) and then be returned to the zero position, so that the needle (3) closes the nozzle (4). 9. Fuel injection method with a fuel injector according to one of claims 1 to 7, in that the pressure control valve (14) is displaced continuously from zero position to displaced position totally, with a percentage of valve displacement (14) pressure control, set so that the needle (3) temporarily open the nozzle (4) partially and then open totally the nozzle (4). 10. Fuel injection method with a fuel injector according to one of claims 1 to 7, in that the fuel injector selectively carry out one of between a low-rate fuel injection in which the pressure control valve (14) is moved to position intermediate and then returned to the zero position, and an injection of high-rate fuel in which the control valve (14) of the pressure is displaced to the fully displaced position and is then returned to the zero position. 11. Method according to claim 10, wherein before a main fuel injection, the injector (1) of fuel additionally performs fuel injection high fee and low fuel injection, successively. 12. Method according to claim 10, wherein, after a main fuel injection, the injector (1) of fuel additionally performs the injection of high quota fuel and quota fuel injection Go down, on. 13. Method according to claim 10, wherein when the fuel injector (1) must carry out the low-rate fuel injection, control valve (14) of the pressure is displaced in a displacement greater than the displacement required for intermediate position. 14. Method according to claim 10, wherein when the fuel pressure supplied to the injector (1) of fuel is higher than an upper threshold, the injector (1) of fuel carries out the quota fuel injection low. 15. Method according to claim 10, wherein when the fuel pressure supplied to the injector (1) of fuel is lower than a lower threshold, the injector (1) of fuel carries out the fuel injection fee high.