WO2004081366A1

WO2004081366A1 - Fuel injection valve and method for the mounting thereof

Info

Publication number: WO2004081366A1
Application number: PCT/DE2004/000100
Authority: WO
Inventors: Hubert Stier
Original assignee: Robert Bosch Gmbh
Priority date: 2003-03-12
Filing date: 2004-01-23
Publication date: 2004-09-23
Also published as: DE10310788A1

Abstract

The invention relates to a fuel injection valve (1), especially a fuel injection valve (1) for fuel injection systems in internal combustion engines. Said fuel injection valve comprises a piezoelectric or magnetostrictive actuator (4), a housing (2), a valve closing body (29) which is arranged in the housing (2), said body co-operating with a valve seat surface (30) in order to form a tight seat, and a hydraulic coupler (18). Said actuator (4) is arranged in an actuator module (34) which can be premounted and the hydraulic coupler (18) can be arranged in a coupler module (30) which can also be premounted.

Description

Fuel injector and method for assembling it

State of the art

The invention relates to a fuel injector according to the preamble of claim 1 and a method for assembling such a fuel injector according to claim 14.

DE 35 33 085 AI discloses a metering valve for metering liquids or gases, in particular an injection valve for fuel injection systems in internal combustion engines, which has a piezo stack actuator, the change in length of which is transmitted to a valve needle controlling a metering opening when an excitation voltage is applied, and determines the stroke of the valve needle. The substance to be measured is fed via a feed line, which is designed in the form of a deep hole in the valve body.

A disadvantage of the injector known from DE 35 33 085 AI is that the housing of the injector is very solid and thus heavy and voluminous. It requires a large installation space and increased material and manufacturing costs. Another disadvantage is that the assembly of the fuel injector is time consuming and requires a large number of non-interchangeable process steps.

Advantages of the invention

The fuel injector according to the invention with the characterizing features of claim 1 and the method for assembling a fuel injector with the features of claim 14 has the advantage that the fuel injector is constructed modularly from a valve module, an actuator module and a feed module, whereby on the one hand the fuel through the Is guided inside the fuel injector and a solid housing with a deep hole can be omitted and on the other hand a simple and inexpensive manufacture and assembly and a reliable reduction of sources of error is possible. ^'

The measures listed in the subclaims allow advantageous further developments of the fuel injector specified in the main claim.

The housing is advantageously of tubular design and can be produced, for example, by deep drawing.

In a further advantageous embodiment variant, the housing is provided with elevations which protrude into the interior of the housing in such a way that the modules can be centered. The elevations are arranged in two rows to center the respective module.

Another advantage is that the modules can be easily fixed to the housing by means of welds.

Another advantage is that the modules can be checked individually before final assembly. drawing

Embodiments of the invention are shown in simplified form in the drawing and explained in more detail in the following description. Show it:

1 shows a schematic section through a fuel injection valve according to the prior art,

2A shows a schematic section through a first exemplary embodiment of a fuel injector designed according to the invention;

FIG. 2B shows a schematic section through the individual modules of the exemplary embodiment of a fuel injector designed according to the invention shown in FIG. 2A;

FIG. 2C shows a detail from the first exemplary embodiment shown in FIG. 2A of a fuel injector designed according to the invention in the area IIC in FIG. 2A;

3A shows a schematic section and the valve housing of the exemplary embodiment illustrated in FIGS. 2A-2C and

3B shows a schematic section through the valve housing of a second exemplary embodiment of a fuel injector designed according to the invention.

Description of the embodiments

Exemplary embodiments of the invention are described below by way of example. Matching components are provided with the same reference numerals in all figures.

Before the invention is described in more detail using preferred embodiments, a fuel injector according to the prior art is briefly explained in its essential components for better understanding. That _. Fuel injector 1 shown in FIG. 1 is in the form of a fuel injector 1 for fuel injection systems of mixture-compressing, spark-ignited internal combustion engines. The fuel injection valve 1 is particularly suitable for injecting fuel directly into a combustion chamber (not shown) of an internal combustion engine.

The fuel injection valve 1 comprises a housing 2, in which a piezoelectric or magnetostrictive actuator 4 provided with an actuator coating 3 is arranged. An electrical voltage can be supplied to the actuator 4 by means of an electrical line 5, on which an electrical connection 6 protruding from the housing 2 can be formed. The actuator 4 is supported on the inflow side on an actuator base 7 and on the outflow side on an actuator head 8. A biasing spring 9 acts on the actuator 4 with a bias. The bias is adjustable by a ring 20 inserted into the housing 2. On the outflow side of the biasing spring 9, a seal 21, which is designed as a corrugated tube seal in the exemplary embodiment, is arranged. This seals the actuator 4 against the fuel flowing through the fuel injection valve 1.

The housing 2 has a bore 10, which is used for the fuel line from an inlet connection 11 to a sealing seat of the fuel injector 1 described in more detail below. The bore 10 is made in the housing 2 parallel to the actuator 4 and made in two parts. A first section 12 is introduced obliquely into the housing 2 and extends from the inlet connection 11 to a second section 13, which extends in a straight line through the housing 2 over its entire axial extent. The reason for the two-part design is the impossibility of producing a kinking bore 10 inexpensively and simply in one operation. The second section 13 is closed on the inflow side of an opening 14 into the first section 12 with a closure body 15.

An actuating element 16 is arranged on the outflow side of the actuator head 8 and acts on a master piston 17 of a hydraulic coupler 18. A slave piston 19 is arranged on the outflow side of the master piston 17 and is arranged together with the latter in a coupler housing 22. The slave piston 19 acts on a valve needle 23, which has a valve closing body 24 at its downstream end. This interacts with a valve seat surface 25, which is formed on a nozzle body 26, to form a sealing seat. A return spring 27 acts on the valve needle 23 so that the fuel injector 1 remains in the closed state when the actuator 4 is deenergized and after the injection phase ensures the resetting of the valve needle 23. A tension screw 28 holds the nozzle body 26 in its position in the housing 2 of the fuel injector 1.

A disadvantage of the described fuel injection valve 1 according to the prior art is the solid housing 2, which must have a minimum wall thickness so that a bore 10 with a sufficient diameter can be made. As a result, the fuel injector 1 is very solid. A corresponding receiving bore in a cylinder head of the internal combustion engine must also be large enough to accommodate the fuel injector 1. Furthermore, the assembly of the fuel injector 1 is labor-intensive and therefore cost-intensive. 2A to 2C show different parts of a first exemplary embodiment of a fuel injector 1 according to the invention, which is of modular construction.

2B shows the individual modules of the fuel injection valve 1 according to the invention before assembly. A coupler module 30 is shown below, which essentially consists of a nozzle body 26. A valve needle 23 is arranged in the nozzle body 26 and has a valve closing body 24 at its downstream end, which forms a sealing seat with a valve seat surface 25 formed on the nozzle body 26. The valve needle 23 is operatively connected to a slave piston 19 of a hydraulic coupler 18. The slave piston 19 is open in a pot shape in the outflow direction. In the recess of the slave piston 19, a return spring 27 is arranged, which holds the valve closing body 24 in the non-actuated state of the fuel injector 1 in sealing contact with the valve seat surface 25.

On the inflow side of the slave piston 19, a master piston 17 is arranged, which is also cup-shaped. Between a collar 31, which is formed on the master piston 17, and the nozzle body 26, a coupler spring 32 is arranged, which returns the hydraulic coupler 18 to its starting position after the fuel injector 1 has been actuated.

In the wall of the nozzle body 26, a bore 33 is provided on the outflow side of the slave piston 19, through which the fuel supplied via a fuel supply (not shown in FIG. 2A) is guided to the sealing seat.

The coupler module 30 can be assembled in a simple manner by inserting the valve needle 23 into the nozzle body 26 and connecting it from the inflow side to the slave piston 19, in which the return spring 27 is inserted, by pressing or welding. Thereafter, the one with the coupler spring 32 is also provided on the inflow side Master piston 17 in the nozzle body 26, which thus also as

Coupler housing is used, inserted. The coupler module 30 is thus preassembled and its function can be checked independently of the other components of the fuel injector 1.

An actuator module 34, which can also be preassembled, is shown at the top in FIG. 2B. The actuator module comprises a piezoelectric or magnetostrictive actuator 4, which is provided with an actuator coating 3 for better heat dissipation. The actuator 4 is supported on the inflow side on an actuator base 7 and on the outflow side on an actuator head 8. The actuator 4 is encapsulated in an actuator cartridge 35, in which a biasing spring 9 is additionally arranged, which biases the actuator 4. On the outflow side of the actuator head 8, an actuating element 16 is provided, which acts on the master piston 17 of the coupler module 30 after complete assembly. The actuator cartridge 35 is sealed by a seal 21, which can be designed, for example, as a corrugated tube seal 21.

The actuator base 7 has a bore 36 and at least one, in the exemplary embodiment two, radial bores 37 which serve for the fuel line.

The assembly of the actuator module 34, like the assembly of the coupler module 30, is also simple and can be carried out in a few steps. The bias spring 9 is inserted into the actuator cartridge 35, then the actuating element 16 is mounted with the actuator head 8. The seal 21 is welded to the actuator cartridge 35, for example. Subsequently, the actuator 4 is inserted into the actuator cartridge 35 and the actuator base 7 is placed on it. The actuator cartridge 35 can be welded to the actuator base 7, for example. By in Fig ^' . 2A bores not shown, the actuator overmolding 3 can take place. The actuator module can now also be checked independently of the other components of the fuel injector 1. After the pre-assembly of the coupler module 30 and the actuator module 34, the modules 30 and 34 are inserted into the housing 2. 2A shows the fully assembled fuel injector 1 with a fuel inlet 43 to be fitted after the modules 30, 34 have been installed. For the sake of clarity, the same components are only provided with the most important reference numerals.

During the final assembly, the coupler module 30 is first inserted into the housing 2 until it abuts a shoulder 38 of the housing 2. The nozzle body 26 passes through an opening 39 in the downstream end of the housing 2. After the coupler module 30 has been correctly aligned in the housing 2, the components are fixed, for example by a first weld 40. Next, the actuator module 34 is pushed into the housing. The axial position of the actuator module 34 relative to the coupler module 30 can be adjusted either by an adjusting disk 41 to be inserted into the master piston 17 of the hydraulic coupler 30 during preassembly or by means of an axial displacement of the coupler module 30 in the housing 2 and subsequent fixation by a second weld 42 in the desired one Position.

The fixation by the second weld 42 is shown in more detail in the section shown in FIG. 2C, designated IIC in FIG. 2A. The weld seam 42 fixes both the actuator module 34 in its axial position and the actuator module 34 on the housing 2.

Finally, a tube 44 with a connecting piece 45 is inserted into the bore 36 and up to the actuator base 7, which, like the connecting piece 45, has a labyrinth seal 46, is provided with a plastic encapsulation 47, into which an electrical connection 29 can also be integrated.

To make it easier to center the modules 30 and 34 in the housing 2, the housing 2 can be compared, as in FIG. 3A 3A, also regularly distributed over the circumference of the housing 2 and having elevations 49 protruding into an interior 48 of the housing 2, which elevations flow between the actuator cartridge 35 and the housing 2 or between the nozzle body 26 and the housing 2 Do not hinder fuel flowing to the sealing seat, but allow exact centering of the modules 30 and 34.

The elevations 49 are preferably arranged in two rows 50, each of which is arranged such that a row of elevations 49 is available for centering per module 30, 34.

The invention is not restricted to the exemplary embodiments shown and is suitable for any designs of fuel injection valves 1.

Claims

Expectations

1. Fuel injection valve (1), in particular fuel injection valve (1) for fuel injection systems of internal combustion engines, with a housing (2) with a piezoelectric or agnetostrictive actuator (4) which actuates a valve closing body (29) arranged in the housing (2) cooperates with a valve seat surface (30) to form a sealing seat, and with a hydraulic coupler (18), characterized in that the actuator (4) in a preassembled actuator module (34) and the hydraulic coupler (18) in a preassembled coupler module (30) are arranged.

2. Fuel injector according to claim 1, characterized in that the coupler module (30) and the actuator module (34) in the housing (2) of the fuel injector (1) can be inserted.

3. Fuel injection valve according to claim 2, characterized in that the housing (2) is designed as a deep-drawn part.

4. Fuel injection valve according to one of claims 1 to 3, characterized in that the housing (2) is tubular.

5. Fuel injection valve according to one of claims 1 to 4, characterized in that the housing (2) at an outflow end

Has opening (39).

6. Fuel injection valve according to claim 5, characterized in that the coupler module (30) passes through the opening (39).

7. Fuel injection valve according to claim 6, characterized in that the coupler module (30) rests on a shoulder (39) of the housing (2).

8. Fuel injection valve according to claim 7, characterized in that the coupler module (30) by means of a first weld

(41) on the housing (2) is fixed.

9. Fuel injection valve according to claim 8, characterized in that the actuator module (34) by means of a second weld

(42) on the housing (2) is fixed.

10. Fuel injection valve according to claim 9, characterized in that the axial position of the actuator module (34) in the housing (2) is predetermined by the second weld seam (42).

11. Fuel injection valve according to claim 9, characterized in that the axial position of the actuator module (34) in the housing (2) is predetermined by an adjusting disc (41).

12. Fuel injection valve according to one of claims 1 to 11, characterized in that the housing (2) in an interior (48) has circumferentially arranged ridges (49).

13. Fuel injection valve according to claim 12, characterized in that the elevations (49) are arranged in two rows (50).

14. A method for assembling a fuel injector (1), in particular a fuel injector (1) for

Fuel injection systems of internal combustion engines, with a housing (2), with a piezoelectric or magnetostrictive actuator (4) which actuates a valve closing body (29) arranged in the housing (2), which cooperates with a valve seat surface (30) to form a sealing seat, and with a hydraulic coupler (18), the actuator (4) being arranged in a preassembled actuator module (34) and the hydraulic coupler (18) being arranged in a preassembled coupler module (30), characterized by the following method steps:

- Pre-assembling the coupler module (30) from a nozzle body (26), a hydraulic coupler (18) and one

Valve needle (23);

- Pre-assembling the actuator module (34) from a piezoelectric or magnetostrictive actuator (4), an actuator cartridge (35), an actuating body (16) and an actuator foot (7);

- Mounting the coupler module (34) in the housing (2);

- Fixing the coupler module (34) by means of a first weld (40);

- Mounting the actuator module (30) in the housing (2); - Fixing the actuator module (30) by means of a first weld seam (42); and

- Assemble a fuel supply (43).