WO2018141335A1

WO2018141335A1 - Fuel injector for an internal combustion engine

Info

Publication number: WO2018141335A1
Application number: PCT/DE2018/100069
Authority: WO
Inventors: Hans-Joachim Koch; Frank Grässler
Original assignee: L'orange Gmbh
Priority date: 2017-02-01
Filing date: 2018-01-29
Publication date: 2018-08-09
Also published as: DE102017101999A1

Abstract

The invention relates to a fuel injector for an internal combustion engine comprising a pilot valve for controlling the stroke motion of a nozzle needle, an armature rod of the pilot valve being guided in a guide bore, which a transition space adjoins. In the transition space, an axially movable transmission element is arranged, which closes the guide bore in defined states of the armature rod.

Description

DESCRIPTION

Fuel injection injector for an internal combustion engine

The invention relates to a fuel injection injector for an internal combustion engine with a pilot valve for controlling the lifting movement of a nozzle needle according to the preamble of claim 1.

A fuel injection injector known from DE 10 2011 051 903 A1 has a pilot valve with an anchor rod which is lifted when the pilot valve is actuated by electromagnetic means, whereupon a nozzle needle of the fuel injection injector is lifted out of its sealing seat and fuel exits. The anchor rod is guided axially displaceably in a guide bore in a pilot valve housing. The guide bore is adjoined by a transitional space of larger diameter, which is bounded by a control chamber bushing with a throttle channel introduced therein. The anchor rod acts on a closing body in a closed position, which closes the throttle channel in the control chamber socket. In an electromagnetic operation, the anchor rod is raised, and it can fuel that is under a high pressure, flow from a control chamber in the control chamber via the throttle passage in the transition space. This proportion of fuel, the one

Tax leakage forms can be removed via leakage bores from the transitional space. The invention has for its object to design a fuel injection injector reliable with simple design measures.

This object is achieved with the features of claim 1. The dependent claims indicate expedient developments.

The fuel injection injector according to the invention, with which fuel is injected into the cylinders of an internal combustion engine, has a pilot valve for controlling the lifting movement of a nozzle needle, which is lifted from its sealing seat to carry out the injection process, whereupon fuel exits via an injection nozzle of the injection injector can. The pilot valve has an armature with an anchor rod, wherein the armature can be preferably raised by electromagnetic means for the injection process. The anchor rod is guided in a guide bore in a pilot valve housing and can be adjusted axially in relation to the longitudinal axis of the fuel injection injector including the nozzle needle and anchor rod in the guide bore. The anchor rod is preferably subjected to a force of a spring element, against the spring force of the anchor rod is raised in electromagnetic actuation. To actuate an electromagnetic actuator is preferably integrated into the housing of the pilot valve, is energized in the armature of the pilot valve is raised.

The guide bore, in which the anchor rod is axially guided, adjacent to a transition space, which is preferably also in the pilot valve housing and which is limited on the armature rod opposite side of a control chamber socket. Of the

Transition space is advantageously in the edge region of the pilot valve housing. In the

Control chamber socket is a throttle channel introduced, which in particular runs axially and connects a control chamber within the control chamber socket with the transition space. Of the

Throttling channel is to be closed by an adjustable closing body of the

Anchor rod can be acted upon in the closed position. With the lifting of the anchor rod upon actuation of the pilot valve against the force of a force acting on the anchor rod

Spring element, the closing body releases the throttle channel, whereby a

Fluid communication between the control room and the transition space is created and fuel that is under high pressure, can flow from the control room in the transition space. Then, the nozzle needle is lifted from its sealing seat and can leak fuel through the injector.

The fuel, which during the raising of the anchor rod from the control room in the

Transition space flows, forms a control leakage, which is preferably derived via a discharge channel to the low pressure side of the fuel injection injector. In order to avoid that, especially during the duration of the injection process, the leakage fuel axially propagates into the annular gap between the guide bore and the anchor rod and due to the relatively high temperature and pressure, a coating on the inner wall of the

Forming guide bore or the outer jacket of the anchor rod, an axially adjustable transmission member is arranged in the transition space in the transmission path to the closing body, which closes the guide bore when the throttle channel is open in the control chamber. In order to ensures that the high pressure leakage fuel that flows during the lifting of the anchor rod in the transition space can not propagate into the guide bore, so that a deposit on the inner wall of the guide bore and the outer jacket of the anchor rod is reliably prevented.

If, on the other hand, the anchor rod is in the non-actuated state, in which the armature rod is subjected to force by the force of the spring element in the sealing position, the

Locking body adjusted in the closed position for closing the throttle channel, so that no fuel can flow from the control chamber via the throttle channel in the transition space. The transfer member is in this position, although no longer in his

Guide bore closing position; However, since the throttle channel in the

Control chamber socket is closed by the closing body, no tax leakage in the

Transition space and continue to flow into the guide hole. The transmission member is in the transmission path from the anchor rod to the

Closing body which closes the throttle channel in the control chamber socket in the closed position. The transmission member advantageously connects axially to the anchor rod. The

Closing forces, which are exerted by the spring element on the anchor rod are passed from the anchor rod via the transmission member to the closing body, which is thereby acted upon in the closed position for closing the throttle channel.

According to an advantageous embodiment, the transmission member is as a separate from the

Anchor rod executed component formed adjacent to the front side of the anchor rod. There is advantageously no firm connection between the anchor rod and the

Transmission member. The transmission member is acted upon by the end face of the anchor rod in the direction of the closing position of the closing body. When lifting the armature rod and the opening of the throttle channel, the transmission member is adjusted by the pressure of the control leakage, which flows into the transition space in the guide bore closing position, so that the control leakage is prevented from flowing into the guide bore. The derivation of the tax leakage from the transition space via the discharge channel in the direction of the low pressure side of the fuel.

In an alternative embodiment, the transmission member is either integral with the

Anchor rod formed or formed separately from the anchor rod, but firmly with the Anchor rod connected. In this embodiment, the transmission member is adjusted at nichtaktuiertem pilot valve by the spring element in the same manner as the anchor rod in the direction of the closed position of the closing body. With the actuation of the pilot valve, the anchor rod is lifted against the force of the spring element, as well as the transmission member, which is integral with the anchor rod or firmly connected to the anchor rod. In addition, the pressure of the control leakage, which flows into the transfer space, acts on the

Transmission member and acts on this in the direction of closing the guide bore.

According to an advantageous embodiment, the transfer member is open throttle channel on the mouth opening of the guide bore in the transitional space. Advantageously, the transition space in the radial direction - radially to the longitudinal axis of the fuel injection injector - has a greater extent than the guide bore, so that the

Mouth opening of the guide bore is bounded by an edge which is part of the inner wall of the transitional space.

According to a further advantageous embodiment, the transmission member has a

Support collar, which in the closed position of the transfer member on the

Mouth opening of the guide hole limiting edge rests. This design can be easily realized in a constructive manner and makes it possible to close the mouth opening of the guide bore through the transmission member when the anchor rod of the pilot valve is raised, so that no control leakage can propagate axially into the guide bore.

According to a further advantageous embodiment, the support collar has a

Outer diameter exceeding the inner diameter of the pilot hole by at least 20%. With this size ratio, it is ensured that the transmission member securely closes the guide bore when the anchor rod is raised.

According to a further advantageous embodiment of the mouth opening of the

Guide bore limiting edge formed as an elevated annular bead on which the

Support collar of the transfer member for closing the guide bore rests. The outer diameter of the annular bead, for example, at least approximately

Outer diameter of the support collar correspond. According to yet another advantageous embodiment, the outer diameter of the support collar is at least 30% larger than the outer diameter of the transmission member on the control chamber bushing facing side. This difference in size in the

Outer diameter ensures that the transfer member is a sufficiently large

The control leakage surface provides so that the control leakage entering the transitional space effectively pressurizes the transmission member in the direction of closing the guide bore.

According to yet another expedient embodiment, the transmission member on the side facing the anchor rod on a pin, which preferably projects into the guide bore in all positions of the anchor rod. About the pin in the guide bore, the transmission member is safely and precisely out in the axial direction between the closed position for closing the guide bore and the open position. The axial length of the pin is for example at least 30% of the total axial length of

Transfer link to ensure the desired secure guidance.

The pin of the transmission member may optionally have an at least slightly larger diameter than the control chamber bushing facing portion of the

Transmitting member.

Further advantages and expedient embodiments are the further claims, the

Figures description and the drawings can be seen. Show it:

1 shows a longitudinal section through a fuel injection injector for an internal combustion engine in the region of a pilot valve, via a transmission member a closing body in a

Acted upon closing position in which a throttle channel is closed in a control chamber socket,

Fig. 2 is an enlarged view of the region of the transmission member.

In the figures, the same components are provided with the same reference numerals.

As can be seen from FIG. 1 in conjunction with FIG. 2, the fuel injection injector 1 in a pilot valve housing 2 has a pilot valve 3, which has an armature 4 and a fixed armature 4 connected anchor rod 5 which is axially displaceable in a guide bore 6 in the pilot valve housing 2 - relative to the longitudinal axis 8 of the fuel injection injector 1 - is stored. The pilot valve 3 is formed electromagnetically aktuierbar, wherein in the case of actuation of the armature 4 with the firmly connected anchor rod 5 against the force of a

Spring element 7, which forms a pilot valve spring, is pulled upwards. The actuation is carried out by means of an electromagnetic actuator, which is integrated in the pilot valve housing 2 of the fuel injection injector 1 and during its energization of the armature 4 of the

Pilot valve 3 is raised. In the non-actuated state armature 4 and anchor rod 5 are pressed by the force of the spring element 7 down in the direction of a closed position in which a throttle channel 10 is closed flow-tight in a control chamber socket 9. Here, the anchor rod 5 acts on a transmission member 12, which is located on the front side of the

Anchor rod 5 is against a closing body 11 in the form of a closing ball, which in a recess on the facing end face of the control chamber 9 in the area of

Mouth opening of the throttle channel 10 is seated. The throttle channel 10 in the control chamber 9 is thus closed flow-tight with non-actuated pilot valve 3 of the closing body 11. When actuated pilot valve 3, however, the anchor rod 5 is in the raised open position.

The control chamber 9 is located in a high-pressure chamber 13 which is formed in a nozzle body 14, which adjoins the pilot valve housing 2. The pilot valve housing 2 and the nozzle body 14 are connected to each other via a clamping nut 15. The fuel flows via a high pressure supply line 16 into the high pressure chamber 13 and passes from this into a control chamber within the control chamber 9, wherein the control chamber with the

Throttle channel 10 communicates and is connected via the throttle channel 10 with a transitional space 17 which connects axially to the guide bore 6 and at the

Nozzle body 14 facing edge side of the pilot valve housing 2 is located. The

Transmission member 12 is for the most part arranged in the transitional space 17. The transitional space 17 is connected to a discharge channel for discharging fuel, which in the

Transition space 17 flows. About the discharge channel takes place a derivative of the fuel from the transitional space 17 to the low pressure side.

With the lifting of the anchor rod 5 upon actuation of the pilot valve 3 against the force of the spring rod 7 acting on the anchor rod 5, the closing body 11 releases the throttle channel 10, whereby a flow connection between the control chamber and the transitional space 17th is created and fuel, which is under high pressure, from the control room in the

Transition space 17 can flow. Then a nozzle needle is lifted from its sealing seat and can leak fuel through an injection nozzle. The transmission member 12 has on the armature rod 5 side facing a pin 19 which projects into the guide bore 6. Between the pin 18 and the main body of the transmission member 12 is a support collar 19, the outer diameter is greater than the inner diameter of the guide bore 6 and 5 raised anchor rod 5 closes the mouth opening of the guide bore 6 in the transitional space 17. Of the

Main body 20 of the transmission member 12 is opposite to the pin 18 and is located within the transition space 17. At the top of the main body 20 has the

Transfer member 12 on the control chamber socket 9 side facing a receptacle 21 for receiving the spherical closing body 11. The pin 18 protrudes into the guide bore 6 in all positions of the anchor rod 5. The diameter of the pin 18 is slightly larger than the diameter of the main body 20. The axial length of the pin 18 is for example at least 30% of the axial

Total length of the transfer member, based on pin 18, support collar 19 and

Main body 20, and for example at least 20% of the total axial length below

Inclusion of the receptacle 21. The receptacle 21 may either one-piece component of the transmission member 12 or formed separately from the transmission member 12, but be connected to the transmission member 12.

The edge defining the mouth opening of the guide bore 6, which is part of the inner wall of the transitional space 17, is formed as a raised annular bead 22 (FIG. 2). On this annular bead 22 of the support collar 19 of the transfer member 12 is raised

Anchor rod 5 sealingly and thereby prevents a transfer of fuel, which flows with raised anchor rod 5 and raised closing body 11 via the throttle channel 10 in the transitional space 17, in the guide bore 6 into it. This fuel, which forms a control leak, can thus not spread axially from the transition space 17 into the guide bore 6 when the anchor rod 5 is raised, so that a deposit formation on the inner wall of the guide bore 6 or the outer jacket of the anchor rod 5 is prevented. When the anchor rod 5 is raised, the transmission member 12 is lifted by the pressure of the inflowing into the transitional space 17 fuel from the sealing or closing position, so that the Support collar 19 sealingly pressed against the annular bead 22. The lifting anchor rod 5 is carried out by actuation of the pilot valve. 3

Once the actuation is completed, the anchor rod 5 is pressed by the force of the spring element 7 back down, whereupon the anchor rod 5 and the closing body 11 are pressed into its closed position, in which the throttle channel 10 is closed flow-tight.

Claims

1. Fuel injection injector for an internal combustion engine, with a pilot valve (3) for

Controlling the lifting movement of a nozzle needle, wherein an anchor rod (5) of the pilot valve (3) in a guide bore (6) in a pilot valve housing (2) is guided, to which a

Transitional space (17) connects, which is bounded by a control chamber bushing (9) with a throttle channel (10), wherein the anchor rod (5) acts on an adjustable closing body (11) in a closed position, the throttle channel (10) in the control chamber socket (9 ), characterized in that in the transition space (17) in the transmission path to

Closing body (11) an axially adjustable transmission member (12) is arranged, which closes the guide bore (6) when the control chamber bushing throttle channel (10) is open.

2. Fuel injection injector according to claim 1,

characterized in that the transfer member (12) rests with open Steuerraumbuchsen- throttle channel on the mouth opening of the guide bore (6) in the transition space (17).

3. Fuel injection injector according to claim 2,

characterized in that the transfer member (12) has a support collar (19) in the closed position of the transfer member (12) on which the mouth of the

Guide bore (6) limiting edge rests.

4. Fuel injection injector according to claim 3,

characterized in that the outer diameter of the support collar (19) is at least 20% larger than the inner diameter of the guide bore (6).

5. Fuel injection injector according to claim 3 or 4,

characterized in that the outer diameter of the support collar (19) is at least 30% greater than the outer diameter of the transfer member (12) on the

Control chamber socket (9) facing side.

6. Fuel injection injector according to one of claims 1 to 5,

characterized in that the transmission member (12) in the guide bore (6) wholly or partially projecting pin (18).

7. Fuel injection injector according to claim 6,

characterized in that the axial length of the into the guide bore (6) projecting portion of the pin (18) is at least 30% of the total axial length of the transfer member (12).

8. Fuel injection injector according to one of claims 1 to 7,

characterized in that the mouth opening of the guide bore (6)

limiting edge is formed as a raised annular bead (22).

9. Fuel injection injector according to one of claims 1 to 8,

characterized in that the transmission member (12) is formed separately from the anchor rod (5) and adjacent to the end face of the anchor rod (5).

10. Fuel injection injector according to one of claims 1 to 9,

characterized in that the transitional space (17) is connected to a discharge channel for draining fuel.