JP2007154896A - Injector for fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injector for a fuel injection device capable of pressurizing and supplying fuel, opening or closing an injection port by a nozzle needle, and feeding the supplied fuel into a combustion chamber by this injector again. <P>SOLUTION: The nozzle needle 9 depends on fuel pressure to provide two limited amount of operation lift 11.1, 12.1, and opening or closing of the injection port 10 by the nozzle needle 9 becomes possible by at least one operation member 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an injector for a fuel injection device.

An injection device such as a common rail injection device that injects fuel at a variable pressure has a very steep injection rate for starting normal injection. A large amount of fuel is injected. However, this effect acts negatively on the nitrogen oxides emission rates (NO _X emission rate). A stepped injection rate can be achieved through the gradual release / opening of the nozzle holes or the limited opening characteristics of the nozzle holes, with a positive effect on the discharge rate.

  Many manufacturers of injectors that utilize such injectors and many manufacturers of diesel engines strive to find optimal control of the injection ports. Another possibility of adjusting the amount of fuel to be injected can be realized by a cam-controlled fuel injection pump.

  Besides finding the optimal control of the injection port, the ballistic behavior of the injection hole is known as another problem existing in the injection device. The ballistic behavior of the nozzle hole appears when the injection quantity is small and the fuel injection pressure is low. Due to the short injection time and the inertia effect of the nozzle hole, uncontrolled movement of the nozzle hole occurs. That is, the needle lift amount may be different for each injection process, and therefore, the fuel amount to be injected has a different value.

  On the premise of this, an object of the present invention is to improve the injector of the fuel injection device.

  The new injector must have a limited needle lift or a limited open cross section when the amount of fuel injected is small. Furthermore, the new injector should no longer exhibit a ballistic needle behavior phenomenon.

  This problem is solved by the injector of the fuel injection device described in claim 1.

  The inventors have determined that it is advantageous if the injector injection needle can perform two limited strokes to avoid the above drawbacks in the injector. Both needle strokes can be released, blocked or restricted by specific control mechanisms.

  Based on this recognition, the present invention improves the injector of the injection device in which fuel can be supplied under pressure and the nozzle needle can open or close the injection port and supply the supplied fuel to the combustion chamber again. It is proposed that the nozzle needle has two limited operating lifts depending on the fuel pressure and that the nozzle can be opened or closed by at least one operating member. The injector provided thereby has two needle lifts, each of which provides a limited stroke open cross section.

  The problem of ballistic needle behavior that has emerged in the past is avoided by the novel injector. The new injectors are particularly suitable for cooperating with valves provided on the upstream side, such as a 3-port 2-position switching valve, a pressure control valve and the like, and are therefore suitable for use for multiple injections. For example, the following combinations are possible. For example, a fuel injection device having a variable injection pressure and a 3-port 2-position switching valve provided upstream of the injector can be realized. Furthermore, a cam-controlled fuel injection pump having an injector can be realized.

  It is advantageous if pressure chambers are formed above and below the nozzle needle, respectively, and fuel can be supplied under pressure to these pressure chambers. For example, when the same pressure is applied to the upper pressure chamber and the lower pressure chamber, the needle is held at a specific position. Only after the pressure in one of the pressure chambers has changed, for example, by pressure release, the nozzle needle can move in the direction of the pressure chamber having a slight pressure.

  In one possible embodiment of the injector, at least one operating member, mainly a two-port two-position switching valve, can be arranged, which opens or closes at least one pressure chamber, whereby the pressure between the two pressure chambers. The difference can be sent to the driven nozzle needle.

  In at least one pressure chamber, the pressure suction cross section may be larger than the pressure discharge cross section. With this cross-sectional ratio, the pressure in the chamber can be reduced by reducing the pressure in the pressure chamber.

  In another preferred embodiment of the injector, each of the two limited operating paths of the nozzle needle is provided with at least one spring element that returns the nozzle needle from the end of each operating path to the starting position. The specific opening behavior can be adjusted by the spring constant of the spring element. Spring elements that can be implemented as compression springs or tension springs can be connected in series, and their spring constants can be added.

  As an alternative to an operating path with a spring element, the limited operating path of the nozzle needle may comprise an operating member, mainly a 2-port 2-position switching valve, whereby the movement of the nozzle needle is initiated in this operating path. Or it is stopped. In another possible injector embodiment, fuel can be supplied to the injector with at least one three-port two-position switching valve and / or pressure regulating valve.

  Preferred configurations of the invention will become apparent from the dependent claims and the following description. An embodiment of the present invention will be described in detail with reference to a single drawing, but the present invention is not limited thereto.

  Hereinafter, the present invention will be described with reference to FIG.

  FIG. 1 is a cross-sectional view of an injector 1 of a fuel injection device. Via the fuel supply line 2, the fuel is transferred at high pressure to the upper pressure chamber 13.1 and the lower pressure chamber 13.2. Via the 3-port 2-position valve and the pressure regulating valve 3 in the fuel supply line 2, the value of the transferred fuel pressure is adjusted, and pressurization or depressurization is controlled.

  The fuel is injected into the combustion chamber through the injection port 10. At that time, the nozzle needle 9 opens and closes the injection port 10. In the state shown in FIG. 1, the nozzle needle 9 is in the lower position and holds the injection port 10 closed. When the nozzle needle 9 moves upward, the injection port 10 is opened. As the nozzle needle 9 moves upward, the free injection port 10 becomes larger and the injection amount of the injected fuel also increases.

  Opening and closing of the nozzle needle 9 is controlled by a 2-port 2-position switching valve 5 in the fuel discharge pipe 6. In the state shown in FIG. 1, the 2-port 2-position switching valve 5 is closed. For this reason, the same pressure is applied to the upper pressure chamber 13.1 and the lower pressure chamber 13.2. The pressure applied from above to the piston rod 4 from the upper pressure chamber 13.1 and the pressure applied from below to the nozzle needle 9 from the lower pressure chamber 13.2 are balanced, and the nozzle needle 9 below the piston rod 4 moves downward. It is hold | maintained in a side position and the injection nozzle 10 is hold | maintained closed.

  In order to start the fuel injection process, i.e. to raise the nozzle needle 9 and cause the injection port 10 to open, the 2-port 2-position switching valve 5 is opened. For this reason, the upper pressure chamber 13.1 is depressurized. However, since the cross-sectional area of the outflow restrictor 7 is larger than the cross-sectional area of the inflow restrictor 8, this depressurization of the upper pressure chamber 13.1 proceeds gradually.

  Within the lower pressure chamber 13.2, fuel under pressure may raise the nozzle needle 9 and open the injection port 10. The first spring element 11 opposes the movement of the nozzle needle. The first spring element 11 allows the nozzle needle to move within the front stroke 11.1. Only after the fuel pressure exceeds a certain limit pressure, the nozzle needle 9 is further lifted, and the spring force of the second spring element 12 acts. The second stroke 12.1 of the nozzle needle 9 can proceed while loading the second spring element 12.

  The spring constant of the first spring element 11 is designed to be smaller than the spring constant of the second spring element 12, and only the forward stroke 11.1 of the nozzle needle 9 is performed when the fuel pressure is low.

  It will be appreciated that the features described above and in the claims can be applied not only in the respective combinations described, but also in other combinations or in isolation, without departing from the scope of the invention.

It is sectional drawing of a novel injector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injector, 2 Fuel supply line, 3 3 port 2 position switching valve and pressure control valve, 4 Piston rod, 5 2 port 2 position switching valve, 6 Fuel discharge line, 7 Outflow throttle, 8 Inflow throttle, 9 Nozzle needle DESCRIPTION OF SYMBOLS 10 Injection port, 11 1st spring element, 11.1 Previous stroke, 12 2nd spring element, 12.1 2nd stroke, 13.1 Upper pressure chamber, 13.2 Lower pressure chamber

Claims (8)

An injector (1) of a fuel injection device capable of supplying fuel under pressure, wherein a nozzle needle (9) opens or closes an injection port (10), and the supplied fuel can be supplied again to the combustion chamber by this injector In what is
The nozzle needle (9) performs two limited operating strokes (11.1, 12.1) depending on the fuel pressure, and at least one opening or closing of the injection port (10) by the nozzle needle (9) is performed. Injector characterized in that it is made possible by two operating members (5).   2. The injector according to claim 1, wherein pressure chambers (13.1, 13.2) are formed above and below the nozzle needle (9), and fuel is supplied to the pressure chamber in a pressurized state.   3. At least one operating member (5), mainly a two-port two-position switching valve, is arranged, which opens or closes at least one pressure chamber (13.1). Injector.   Injector according to one of the preceding claims, characterized in that in at least one pressure chamber (13.1), the pressure suction cross section (8) is larger than the pressure discharge cross section (7).   Two limited operating strokes (11.1, 12.1) of the nozzle needle (9) each free at least one spring element (11, 12), which spring element controls the nozzle needle (9) each time 5. Injector according to one of claims 1 to 4, characterized in that it returns from the end of the stroke (11.1, 12.1) to the starting position.   6. Injector according to claim 5, characterized in that the spring elements (11, 12) are connected in series, so that their spring constants are added.   The limited operating stroke (11.1, 12.1) of the nozzle needle (9) is provided with operating members, mainly a 2-port 2-position switching valve, whereby the movement of the nozzle needle (9) is this operating stroke. 5. Injector according to one of claims 1 to 4, characterized in that it is started or stopped within (12.1).   Injector according to one of the preceding claims, characterized in that fuel is supplied to the injector (1) by means of at least one three-port two-position switching valve and / or a pressure regulating valve (3).

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