EP2530293A1 - Fuel injector - Google Patents

Abstract

The fuel injector has an actuator assembly (7) with a magnetic actuator (7.1) for opening a nozzle needle (1) and another magnetic actuator (7.2) is provided for closing the nozzle needle. The magnetic actuator cooperates with an anchor element (9), which is operatively connected with the nozzle needle. The actuator assembly in a low pressure region (8) is directly operated by the nozzle needle. The magnetic actuator of the actuator assembly is a polarized or electrodynamic magnetic actuator, and cooperates with the anchor element that is formed as a flat- or dipping anchor.

Description

The invention relates to a fuel injector for injecting fuel into the combustion chamber of an internal combustion engine having the features of the preamble of claim 1.

Such a fuel injector comprises a nozzle needle, which is guided in a high-pressure bore of a nozzle body for releasing and closing at least one injection opening and is acted upon in the direction of a sealing seat by the spring force of a closing spring, and an actuator assembly, which is arranged in a low pressure region and by means of which the nozzle needle is directly operable.

State of the art

A fuel injector of the type mentioned above, for example, from the published patent application DE 10 2008 041 553 A1 out. Herein, a fuel injector comprising a nozzle needle or an injection valve element is disclosed with an opening direction facing, acted upon by low pressure low pressure surface in combination with a throttle connection. The object of the low pressure surface formed on the injection valve element is to reduce the stationary hydraulic closing force and to generate a hydraulic opening force in the open state. In contrast, the throttle connection is arranged and dimensioned such that the hydraulic opening force counteracts a hydraulic closing force acting in the closing direction when the injection valve element is open, whereby the closing speed of the injection valve element can be increased. The combination of low pressure area and throttle connection causes that required for direct actuation of the nozzle needle Actuator power is reduced, so that comparatively low-power actuators can be used.

Based on the above-mentioned prior art, the present invention has for its object to provide a fuel injector, which allows an increase in the efficiency of injection and combustion. In particular, a fast-opening and fast closing directly operable fuel injector should be specified.

The object is achieved by a fuel injector with the features of claim 1. Advantageous developments of the invention are specified in the subclaims.

Disclosure of the invention

According to the invention, the actuator arrangement of the proposed fuel injector comprises a first magnetic actuator for opening the nozzle needle and a second magnetic actuator for closing the nozzle needle, wherein at least one magnetic actuator cooperates with an anchor element, which is operatively connected to the nozzle needle. For opening and closing the nozzle needle, the actuator arrangement of a fuel injector according to the invention accordingly has at least two magnetic actuators whose effective direction is preferably opposite. In order to be able to effect opening and closing of the nozzle needle, the magnetic actuators of the actuator arrangement can be activated independently of one another.

The closing of the nozzle needle causing magnetic actuator is assisted in its task by the closing spring, the spring force of the nozzle needle in the closing direction, i. in the direction of the sealing seat, acted upon. Accordingly, a comparatively small magnetic actuator can be used to close the nozzle needle. The formation of a closing throttle in order to produce in the open position of the nozzle needle a force acting in the closing direction on the nozzle needle hydraulic closing force is dispensable.

By optimizing the closing process, the efficiency of the injection can be increased so that the same power with reduced injection quantity is achievable. This in turn means that fuel can be saved and CO ₂ emissions can be reduced.

Preferably, at least one magnetic actuator of the actuator assembly is a polarized or electrodynamic magnetic actuator. Alternatively or additionally, it may be provided that the magnetic actuator cooperates with an armature element designed as a flat or plunger armature. Preferably, the magnetic actuators and the at least one anchor element are designed and arranged in such a way that the armature element is moved in the closing direction of the nozzle needle when the one magnet actuator is energized in the opening direction of the nozzle needle and when the other magnet actuator is energized. Each magnetic actuator can also cooperate with its own anchor element.

According to a preferred embodiment of the invention, the anchor member is indirectly operatively connected via a plunger body with the nozzle needle. The plunger body is preferably positively, positively and / or materially connected to the anchor element and coupled to the nozzle needle mechanically or hydraulically in such a way that a movement of the anchor element is transmitted directly or indirectly to the nozzle needle. In this case, the direction of movement of the anchor element of the direction of movement of the nozzle needle correspond or - in reverse control of the nozzle needle - this be opposite. The latter, however, requires a device for reversing the direction of movement. Further, in a transmission of the movement of the anchor element on the nozzle needle, a force or displacement transmission can be effected.

A force or displacement transmission can be effected, for example, by the armature element being operatively connected to the nozzle needle indirectly via a coupler body and / or a hydraulic coupler volume. As a coupler body can also be used with the anchor element force, form and / or cohesively connected plunger body. Preferably, hydraulically effective surfaces are formed both on the coupler body, as well as on the nozzle needle whose size ratio is selected such that a force or Wegverstärkung occurs. The coupler body and / or the coupler volume can also be used to reverse the direction of movement of a magnetic actuator, if its direction of action or the direction of movement of the anchor element is opposite to the direction of movement of the nozzle needle.

The nozzle needle may be formed one or more parts. Preferably, it has a guide portion, with which it is guided in a pressurized with low pressure bore of a holding body. The guide gap between the guide section of the nozzle needle and the wall of the bore formed in the holding body is further preferably designed as a sealing gap, via which the low-pressure region of the fuel injector is sealed against the high-pressure region. A leakage quantity flowing off over the guide area is preferably supplied to a return via the low-pressure area. By the guide portion of the nozzle needle is guided into the low pressure region, the nozzle needle has at least one surface which is acted upon in the closing direction with low pressure. In this way, the actuator force required to open the nozzle needle can be reduced. This has a favorable effect on the design of the magnetic actuator, which is provided for opening the nozzle needle.

wobei F_Feder die Federkraft der die Düsennadel in Richtung des Dichtsitzes beaufschlagende Schließfeder ist. Die auf die geschlossene Düsennadel wirkende Kraft ist demnach direkt über die beiden Durchmesser D_l und D_s einstellbar.Advantageously, the acted upon by low pressure bore of the holding body has an inner diameter D _l , which is smaller than the seat diameter D _{s of} the sealing seat. In the closed position of the nozzle needle then results in approximately the following force on the nozzle needle: $${\mathrm{F}}_{\mathrm{needle}}\mathrm{=}\mathrm{-}{\mathrm{F}}_{\mathrm{feather}}\mathrm{-}\left({\mathrm{D}}_{\mathrm{S}}\mathrm{-}{\mathrm{D}}_{\mathrm{l}}\right)\mathrm{*}{\mathrm{p}}_{\mathrm{Rail}}\mathrm{.}$$

wherein F _{spring is} the spring force of the nozzle needle acting in the direction of the sealing seat closing spring. The force acting on the closed nozzle needle force is therefore directly on the two diameters D _l and D _s adjustable.

The fuel injector according to the invention is preferably designed as a tophead injector, since such an injector has sufficient space for accommodating an actuator arrangement comprising at least two magnetic actuators. However, since compact magnetic actuators can be used with comparatively low power, a fuel injector according to the invention can also be designed as an inline injector.

• Fig. 1 einen schematischen Längsschnitt durch eine erste Ausführungsform eines erfindungsgemäßen Kraftstoffinjektors und
• Fig. 2 einen schematischen Längsschnitt durch eine zweite Ausführungsform eines erfindungsgemäßen Kraftstoffinjektors.

Preferred embodiments of the invention are described below with reference to the drawings. These show:

• Fig. 1 a schematic longitudinal section through a first embodiment of a fuel injector according to the invention and
• Fig. 2 a schematic longitudinal section through a second embodiment of a fuel injector according to the invention.

Detailed description of the drawings

The in the Fig. 1 and 2 Fuel injectors shown each have a nozzle needle 1, which is guided in a high-pressure bore 2 of a nozzle body 3 in a liftable manner. About the lifting movement of the nozzle needle 1 is at least one formed in the nozzle body 3 injection opening 4 can be opened and closed. In order to release the at least one injection opening 4, the nozzle needle 1 must be lifted by a sealing seat 5, which in the present case has a conical shape and cooperates sealingly with a conical sealing surface formed on the nozzle needle. For closing the at least one injection opening 4, the nozzle needle 1 is to be returned to the sealing seat 5.

In the open position of the nozzle needle 1, the at least one injection opening 4 is supplied via the high-pressure bore 2 under high pressure fuel. In the high-pressure bore 2, the high-pressure fuel passes through an inlet bore 16, which via a high pressure port 17 with a high-pressure accumulator (not shown), preferably a rail, is connectable. The inlet bore 16 and the high-pressure port 17 are formed in a holding body 15, which is connected to the nozzle body 3 via a nozzle retaining nut 18.

The lifting movement of the nozzle needle 1, by means of which the at least one injection opening 4 is releasable and closable, is controlled by means of an actuator arrangement 7. The control is direct, that is without the interposition of a servo valve. The direct control has over the indirect control by means of a servo valve on the advantage that the nozzle needle opens and closes faster. Furthermore, eliminating the need to perform a Absteuermenge the servo valve to a return, so that the efficiency of the system is further increased. The for direct control of the nozzle needle 1 provided actuator assembly 7 has in the two in the Fig. 1 and 2 illustrated embodiments in each case two magnetic actuators 7.1, 7.2. The magnetic actuators 7.1, 7.2 are each arranged in a low-pressure region 8. By the arrangement in the low-pressure region 8, on the one hand, the load on the magnetic actuators 7.1, 7.2 reduced, on the other hand, the electrical contacting of the magnetic actuators 7.1, 7.2 are simplified. In order to transmit the force and / or the stroke of the magnetic actuators 7.1, 7.2 to the nozzle needle 1, they each act together with an anchor element 9, which is operatively connected to the nozzle needle 1. The magnetic actuators 7.1 and 7.2 are designed such that the armature element 9 is moved in the closing direction of the nozzle needle 1 when the magnet actuator 7.1 is energized in the opening direction and when the magnet actuator 7.2 is energized. Due to the operative connection of the anchor element 9 with the nozzle needle 1, this is entrained, so that an alternating energization of the two magnetic actuators 7.1, 7.2 causes opening and closing of the nozzle needle 1. In addition, the nozzle needle 1 is acted upon in the closing direction by the spring force of a closing spring 6, so that the magnetic actuator 7.2, which should cause a closing of the nozzle needle 1, may have a comparatively low power.

In the embodiment of the Fig. 1 the operative connection of the nozzle needle 1 with the anchor element 9 via a guide portion 13, with which the nozzle needle 1 is received in a bore 14 of the holding body 15. A gap formed between the guide section 13 of the nozzle needle 1 and the holding body 15 is designed as a sealing gap, via which the low-pressure region 8 is sealed off from the high-pressure bore 2. The inner diameter D _{l of} the bore 14 is smaller than the seat diameter D _{s of} the sealing seat 5 is selected. The guide section 13 of the nozzle needle 1 is in the present case non-positively and positively connected to the anchor element 9. The trained as a flat armature anchor element 9 is for this purpose penetrated by the guide portion 13. The anchor member 9 is also acted upon in the closing direction of the nozzle needle 1 by the spring force of a compression spring 19, which is arranged as the actuator assembly 7 in the low pressure region 8.

In the embodiment of the Fig. 2 the operative connection of the nozzle needle 1 with the anchor element 9 via a coupling device for amplifying the actuator force. The coupler device can be used as a coupler body 11 Plunger body 10, which is positively and positively connected to the anchor member 9, and a hydraulic coupler volume 12 which is formed in the bore 14 of the holding body 15 and in the axial direction on the one hand by an end face of the plunger body 10 and on the other hand by an end face of the nozzle needle. 1 is limited. The movement of the anchor element 9 is transmitted via the coupling device to the nozzle needle 1 such that a force transmission takes place. The force transmission in the present case is> 1.

About that in the Fig. 2 illustrated embodiment also coupler devices are possible, with which a force transmission <1 or = 0 can be displayed. In addition, an inverse coupler can be provided, with which a reversal of the direction of movement can be effected, so that the anchor element 9 can also move in the opposite direction to the nozzle needle 1. Furthermore, it is possible to lay the coupler device in the high-pressure region of the injector.

Claims (7)

Fuel injector for injecting fuel into a combustion chamber of an internal combustion engine comprising a nozzle needle (1) in a high pressure bore (2) of a nozzle body (3) for releasing and closing at least one injection port (4) guided in a liftable manner and in the direction of a sealing seat (5) of the spring force of a closing spring (6) is acted upon, and an actuator arrangement (7) which is arranged in a low-pressure region (8) and by means of which the nozzle needle (1) can be actuated directly,
characterized in that the actuator arrangement (7) comprises a first magnetic actuator (7.1) for opening the nozzle needle (1) and a second magnetic actuator (7.2) for closing the nozzle needle (1), wherein at least one magnetic actuator (7.1, 7.2) with an anchor element ( 9) cooperates, which is operatively connected to the nozzle needle (1). Fuel injector according to claim 1,
characterized in that at least one magnetic actuator (7.1, 7.2) of the actuator assembly (7) is a polarized or electrodynamic magnetic actuator and / or cooperates with an armature element (9) designed as a flat or plunger armature. Fuel injector according to claim 1 or 2,
characterized in that the anchor member (9) is indirectly operatively connected via a plunger body (10) with the nozzle needle (1). Fuel injector according to one of the preceding claims,
characterized in that the anchor element (9) indirectly via a coupler body (11) and / or a hydraulic coupler volume (12) with the nozzle needle (1) is operatively connected. Fuel injector according to one of the preceding claims,
characterized in that the nozzle needle (1) is formed in one or more parts and has a guide portion (13) with which the nozzle needle (1) in a pressurized with low pressure bore (14) of a holding body (15) is guided. Fuel injector according to one of the preceding claims,
characterized in that the acted upon by low pressure bore (14) of the holding body (15) has an inner diameter D _l , which is smaller than the seat diameter D _{s of} the sealing seat (5). Fuel injector according to one of the preceding claims,
characterized in that the fuel injector is designed as a tophead injector or inline injector.

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