EP2047095A1

EP2047095A1 - Fuel injector

Info

Publication number: EP2047095A1
Application number: EP07729829A
Authority: EP
Inventors: Nadja Eisenmenger; Hans-Christoph Magel
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2006-07-24
Filing date: 2007-06-04
Publication date: 2009-04-15
Also published as: DE102006034112A1; US20090206183A1; WO2008012132A1

Abstract

The invention relates to a fuel injector with an injector housing (6) comprising a pressure chamber (15), from which, depending on the pressure in a control chamber (22), pressurized fuel is injected into a combustion chamber of an internal combustion engine when the pressure in the control chamber (22) with the aid of a control valve device (12) is reduced so far, that a nozzle needle (10) opens. In order to present a fuel injector, constructed in a simple and cost efficient way, the pressure chamber (15) is sealed at an end away from the combustion chamber with a valve piece (30) having a sealing face or sealing edge facing away from the combustion chamber and lying against the injector housing (6).

Description

Fuel injector

The invention relates to a fuel injector according to the preamble of claim 1.

State of the art

To introduce fuel into direct-injection diesel engines, stroke-controlled fuel injectors can be used in which the injection pressure can be adapted to load and speed. To control the pressure in the control room solenoid valves or piezo valves can be used.

Disclosure of the invention

The object of the invention is to provide a fuel injector according to the preamble of claim 1, which is simple in construction and inexpensive to produce. The object is in a fuel injector with an injector, which includes a pressure chamber is injected from the depending on the pressure in a control room, high-pressure fuel into a combustion chamber of an internal combustion engine, when the pressure in the control chamber by means of a control valve device so far is lowered, that opens a nozzle needle, achieved in that the pressure chamber is closed at its brennraumfer- end by a valve piece having a combustion chamber facing away from the sealing surface or sealing edge, which bears with sealing effect on the Injektorgehäuse to form a sealing seat. The inventive arrangement of the valve piece provides the advantage that the pressure prevailing in the pressure chamber hydraulic pressure can be used to hold the valve piece under sealing effect in abutment against the injector.

A preferred embodiment of the fuel injector is characterized in that the valve piece has a pressure chamber portion which is arranged in the pressure chamber. The pressure chamber section of the valve piece is acted upon by the hydraulic pressure prevailing in the pressure chamber.

A further preferred embodiment of the fuel injector is characterized in that a valve piston of the control valve device is guided in the valve piece. The valve piston is preferably designed to be pressure balanced.

A further preferred embodiment of the fuel injector is characterized in that that the valve piston rests with its end close to the combustion chamber on a control piece, which in turn bears against the valve piece. Preferably, the valve piston has a sealing edge, which rests as a flat seat on the control piece.

A further preferred embodiment of the fuel injector is characterized in that the combustion chamber remote end of the nozzle needle is guided in the control piece and limits the control space in the control piece. The control piece is preferably held in contact with the valve piece by the spring force of a spring device and / or by the hydraulic pressure prevailing in the pressure chamber.

Another preferred exemplary embodiment of the fuel injector is characterized in that the valve piston has a pressure relief connection. Preferably, the valve piston has a central through hole, which opens into the sealing seat at the combustion chamber near the end of the valve piston and is in communication with a pressure relief space.

A further preferred exemplary embodiment of the fuel injector is characterized in that a valve seat of the control valve device is formed at the end of the valve piece remote from the combustion chamber. The valve seat is designed for example as a ball seat, conical seat or flat seat.

A further preferred embodiment of the fuel injector is characterized in that - A -

that the combustion chamber remote end of the nozzle needle is guided in the valve piece and limits the control chamber. This simplifies the construction and assembly of the fuel injector.

A further preferred embodiment of the fuel injector is characterized in that the nozzle needle comprises two sections which are coupled together. The sections may be coupled together mechanically or hydraulically.

A further preferred embodiment of the fuel injector is characterized in that the valve piece and / or the control piece has at least one connection which connects the pressure chamber with a pressure chamber or the pressure chamber or the pressure chamber with the control chamber. Preferably, the connection is equipped with a throttle.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the drawing, various embodiments are described in detail.

Brief description of the drawings

Show it:

Figure 1 is a schematic representation of a fuel injector according to the invention in Long section according to a first exemplary embodiment;

Figure 2 shows a similar fuel injector as in Figure 1 according to a second embodiment and

FIG. 3 a section of a fuel injector according to a further embodiment in longitudinal section.

Description of the exemplary embodiments

1 shows a fuel injector 1 is shown schematically in longitudinal section. The fuel injector 1 is supplied from a high-pressure reservoir 2 with fuel under high pressure. Via a feed line 3 of the fuel injector 1 is connected to the high-pressure accumulator 2.

The fuel injector 1 comprises an injector housing 6 with an injector body 7 and a nozzle body 8, which has a central guide bore 9. In the Fuhrungsbohrung 9 a nozzle needle 10 is guided back and forth movable. The nozzle needle 10 has a tip 11, on which a sealing surface is formed, which forms a sealing seat at the projecting into the combustion chamber end of the Dusenkorpers 8. When the nozzle needle seat is closed at the tip 11 of the nozzle needle 10, then a plurality of spray holes are closed in the Dusenkorper 8. When the nozzle needle tip 11 lifts from its seat, then high-pressure fuel through the injection holes injected into the combustion chamber of the internal combustion engine.

The opening movement of the nozzle needle 10 is controlled by a control valve 12, which is also referred to as a metering valve.

On the nozzle needle 10, a pressure shoulder 14 is formed, which is arranged in a pressure chamber 15 which extends in the nozzle body 8 and the Injektorkor- by 7. The nozzle needle 10 is biased by a compression spring 16 with its tip 11 against the Dusenkorper 8. At the nozzle needle 10 flats 17, 18 are formed, which allow the passage of fuel from the part of the pressure chamber 15 which is provided in the Injektorkorper 7, in the part of the pressure chamber 15 in which the pressure shoulder 14 is arranged.

At the nozzle needle 10, a spring plate 19 or collar 19 is attached. The compression spring 16 is clamped between the spring plate 19 and a control stub 20, which has a guide bore 21 for the end of the nozzle needle 10 remote from the combustion chamber. The combustion chamber remote end face of the nozzle needle 10 is limited in the control piece 20 a control chamber 22. The control chamber 22 is connected via a connecting channel 24 having a throttle, with the pressure chamber 15 in connection. The combustion chamber remote end of the Steuer- Stuck 20 is to form a sealing seat to the combustion chamber near the end of a Ventilstucks 30. The valve stucco 30 in turn rests against the injector body 7 to form a sealing seat 31. In the combustion chamber near end face of the valve member 30, a pressure chamber 32 is recessed, which communicates with the control chamber 22 via a connecting channel 34 which is provided in the valve member 20 and equipped with a throttle. The pressure chamber 32 is connected via a further connecting channel 35, which is provided in the valve piece 30 and equipped with a throttle, with the pressure chamber 15 in connection.

In an axial through hole of the valve piece 30, a valve piston 38 is guided reciprocally movable. The combustion chamber near the end of the valve piston 38 is located at the combustion chamber remote end face of the control piece 20 to form a sealing seat 39. Within the sealing seat 39 opens a central through hole 40 which is provided in the valve piston 38. The central through-hole 40 opens at its end remote from the combustion chamber into a pressure relief chamber 41 which, as indicated by an arrow 42, communicates with a fuel collecting container (not shown).

The valve piston 38 is biased by a spring 43 toward the combustion chamber, so that the provided at the combustion chamber near the end of the valve piston 38 sealing seat 39 is closed. At the combustion chamber remote end of the valve piston 38, a magnet armature 44 is fixed, which cooperates with an electromagnet 45. When the electromagnet 45 is energized, then the armature 44 is attracted to the electromagnet 45, so that the sealing seat 39 opens at the combustion chamber near the end of the valve piston 38. When the sealing seat 39 opens, the pressure Chamber 32 and via the connecting channel 34 also the control chamber 22 depressurized. By this pressure relief at the combustion chamber remote end of the nozzle needle 10, the nozzle needle tip 11 lifts from its seat on the nozzle body 8, so that fuel is injected into the combustion chamber.

The nozzle needle 10 of the illustrated in Figure 1 Kraftstoffinj ector 1 includes a combustion chamber near the nozzle portion 51 which is materially connected to a combustion chamber distant nozzle needle portion 52. In order to avoid tensioning of the nozzle needle 10 due to production inaccuracies, thin compensating webs 53 to 56, which act like a cardan joint, are provided in the nozzle needle section 52. As an alternative to a long nozzle needle 10, a two-part nozzle needle / control rod combination can be used, wherein the nozzle needle and the control rod are connected to each other either mechanically or hydraulically.

The connecting channel 24 represents an inlet channel for the control chamber 22. The associated throttle is also referred to as inlet throttle. The connecting duct 34 represents a drainage channel. The associated throttle is also referred to as a drainage throttle. The connecting channel 35 with the associated throttle is optional and allows when closing the nozzle needle 10, a filling of the control chamber 22 via the outlet throttle in the drain passage 34. Thus, the closing speed of the nozzle needle 10 can be increased. Additional spring or holding elements may be provided. be seen to fix the valve member 30 in its rest position.

2 shows a fuel injector 61 is shown schematically in longitudinal section, which is similar to the fuel injector 1 of Figure 1. To designate the same parts, the same reference numerals are used. To avoid repetition, reference is made to the preceding description of FIG. In the following, the differences between the two embodiments are mainly discussed.

In the case of the fuel injector 61 shown in FIG. 2, the part of the pressure chamber 15 in which the pressure shoulder 14 is arranged communicates via a pressure connection channel 62 with the part of the pressure chamber 15 which is arranged in the injector body 7. The nozzle needle 10 is equipped with a nozzle needle extension 62, which is coupled to the nozzle needle 10 by means of a hydraulic coupler 64. The hydraulic coupler 64 comprises a coupler sleeve 65, in which the combustion chamber near the end of the nozzle needle extension 63 is guided. The coupler sleeve 65 is biased against the nozzle body 8 by means of a spring 66, which is supported on a collar 67 of the nozzle needle extension 63.

The fuel injector 61 shown in FIG. 2 comprises a control valve 12 with a valve piece 70. The valve piece 70 has a guide section 71 close to the combustion chamber and a sealing section 72 remote from the combustion chamber. In the guide section 71, the valve piece 70 has a guide bore 74 on, in which the combustion chamber remote end of the nozzle needle 10 and the Dusennadelverrascherung 63 is guided.

The combustion chamber remote end face of the nozzle needle 10 and the Dusennadelverrascherung 63 limited in the Ventilstuck 70 a control chamber 75. The control chamber 75 is connected via a connecting channel 76 which is equipped with a throttle, with the pressure chamber 15 in connection. The control chamber 75 is connected via a further connecting channel 77, which is also equipped with a throttle, with a pressure chamber 78 in connection, which has the shape of a blind hole from which a further connecting channel 79, which is also equipped with a throttle, in the Pressure chamber 15 extends.

The pressure chamber 78 forming blind hole is closed at its combustion chamber remote end by a valve ball 80. The valve ball 80 is held by the biasing force of a spring 81 in abutment against the combustion chamber remote opening of the pressure chamber 78. Between the spring 81 and the valve ball 80, a magnet armature 82 is arranged, on which the valve ball 80 is fixed. The armature 82 cooperates with an electromagnet 83 and is arranged in a pressure relief space 85. The pressure relief space 85, as indicated by an arrow 86, communicates with a Kraftstoffsam- melbehalter.

In the idle state, the control valve 12 designed as a ball valve is closed. When the electromagnet 83 is energized, then the magnet armature 82 is attracted with the valve ball 80 to the solenoid 83, so that the valve ball 80 lifts from its associated valve seat at the combustion chamber distal end of the pressure chamber 78. Then, the pressure chamber 78 and the connecting channel 77 of the control chamber 75 is relieved, so that the nozzle needle 10 lifts with its tip 11 from the associated valve seat.

In Figure 3, a further exemplary embodiment is shown in section. A nozzle needle 90 is arranged in an injector housing 91 which is supplied with fuel via a feed line 92, which enters a pressure chamber 94 in the interior of the injector housing 91. The opening and closing of the nozzle needle 90 is controlled by a valve device 95 comprising a valve stub 100. Valve Stuck 100 is inserted into the injector housing 91 from the combustion chamber end and seals via a flat sealing seat 102 to the injector housing. The sealing seat 102 is held closed by a spring 103.

In the valve stub 100, a control chamber 101 is formed, which is delimited by the combustion chamber distal end of the nozzle needle 90. The control chamber 101 is connected via a connecting channel 104, which has a throttle, with the pressure chamber 94 in connection. Furthermore, the control chamber 101 is connected via a further connecting channel 105, which is also equipped with a throttle, with a space which is bounded within a sealing seat 106 by a magnet armature 108. The armature 108 is by a spring 109 against the valve Stuck 100th biased so that the sealing seat 106 is closed. When the armature 108 is actuated by an electromagnet 110, the sealing seat 106 is opened. In the armature 108, a balance piston 112 is received. When the sealing seat 106 is opened, a connection is released from the control chamber 101 via the connection channel 105 into a pressure relief space 115.

Claims

R. 314581Patentansprüche

1. Fuel injector with an injector housing (6, 91), which comprises a pressure chamber (15, 94), from which depending on the pressure in a control chamber (22, 75, 101) high-pressure fuel into a combustion chamber of a Internal combustion engine is injected when the pressure in the control chamber (22; 75; 101) by means of a control valve device (12; 95) is lowered so far that a nozzle needle (10; 90) opens, characterized in that the pressure chamber (15; 94) is closed off at its end remote from the combustion chamber by a valve piece (30; 70; 100) which has a sealing surface or sealing edge facing away from the combustion chamber, which bears on the injector housing (6; 91) with a sealing effect.

2. Fuel injector according to claim 1, characterized in that the valve piece (30; 70; 100) has a pressure chamber section which is arranged in the pressure chamber (15; 94).

3. Fuel injector according to one of the preceding claims, characterized in that a valve piston (38) of the control valve device (12) in the valve piece (30) is guided.

4. fuel injector according to claim 3, characterized in that the valve piston (38) with his near the combustion chamber end rests against a control piece (20), which in turn bears against the valve piece (30).

5. fuel injector according to claim 4, characterized in that the combustion chamber remote end of the nozzle needle (10) in the control piece (20) is guided and the control chamber (22) in the control piece (20) limited.

6. fuel injector according to one of claims 3 to 5, characterized in that the valve piston (38) has a pressure relief connection (40).

7. Fuel injector according to claim 1 or 2, characterized in that at the combustion chamber remote end of the valve piece (70) has a valve seat of the control valve device (12) is formed.

8. fuel injector according to any one of claims 1, 2 or 7, characterized in that the combustion chamber remote end of the nozzle needle (10) is guided in the valve piece (70) and limits the control chamber (75).

9. Fuel injector according to one of the preceding claims, characterized in that the nozzle needle (10) comprises two sections (51, 52, 63) which are coupled together.

10. fuel injector according to any one of the preceding claims, characterized in that the valve piece (30; 70; 10) and / or the control piece

(20) at least one connection (24, 34, 35, 76, 77, 79) has, which connects the pressure chamber with a pressure chamber or the pressure chamber or the pressure chamber with the control chamber.