DE102013225817A1 - Fuel injector - Google Patents

Abstract

A fuel injection valve (1) for fuel injection systems of internal combustion engines, in particular for direct injection of fuel into the combustion chamber of an internal combustion engine, comprises a magnetic coil (10), an armature (20) acted upon by the magnetic coil (10) in a closing direction by a return spring (23). and a valve needle (3), which is non-positively connected with the armature (20), for actuating a valve-closing body (4) which forms a sealing seat together with a valve seat surface (6). In one of the inlet side fuel supply (16) serving connection sleeve (40), an adjusting element (50) for adjusting the spring force of a return spring (23) is arranged. The adjusting element (50) consists of a sintered metal powder and has e.g. different porosities in at least two sections.

Description

State of the art

The invention relates to a fuel injection valve according to the preamble of the main claim.

From the DE 40 03 228 A1 For example, a fuel injector is known in which a fuel filter is press-fitted into the fuel inlet port at the upstream end of the fuel injector. This fuel filter is provided at the periphery, for example, with a brass ring which forms the mating with the wall of the Brennstoffeinlassstutzens when pressing the fuel filter. The brass ring surrounds an annular solid plastic section of the main body of the fuel filter, from which extend, for example, three webs in the longitudinal direction to a common bottom portion, of which the actual screen mesh is encapsulated in these sub-areas. An adjusting sleeve downstream of the fuel filter is used to adjust the spring bias of a voltage applied to the adjusting return spring.

Furthermore fuel injectors are already known in which the adjusting sleeve and the fuel filter are present as a so-called combination component, ie the two functions of adjusting the spring preload of a restoring spring resting against the adjusting sleeve and the filtering of the incoming fuel are integrated in one component ( US 5,335,863 A . US Pat. No. 6,434,822 B1 . EP 1 296 057 B1 . EP 2 426 351 A1 . EP 1 377 747 A1 ). All known solutions are characterized by the fact that a pressing area is provided in the adjustment sleeve, which enters into a press fit with the wall of the surrounding connecting piece, which is chosen so tight that over the life of the fuel injection valve, the spring tension remains constant, so a Slipping of the adjusting sleeve is excluded.

Advantages of the invention

The fuel injection valve according to the invention with the features of the main claim has the advantage that an adjustment is used as a combined component in the fuel inlet, that combines a high functional integration (adjustment of the spring force of the return spring, filtering of the fuel, damping of pressure pulsations) in itself, the adjustment particularly simple and process reliable. Advantageously, the adjusting element consists of a sintered metal powder and therefore has a porous structure. In this way, a filter element can be integrated directly into the adjusting element, since the filter function is produced by the porous structure of the adjusting element produced by sintering. The entire adjustment can take over the filtering of the fuel flowing through it; Alternatively, the filter structure may also be provided only in sections.

Ideally, the filter structure may be chosen so that the function of throttling the fuel flow is also integrated. With very low additional costs and also easy to produce so far a significant noise reduction compared to fuel injectors of similar design and comparable structural design achievable.

The measures listed in the dependent claims advantageous refinements and improvements of the main claim fuel injector are possible.

It is advantageous to provide the adjustment with a consistently identical porosity, since this manufacturing technology, the least effort is required.

However, it can also be very interesting to provide the adjustment element in at least two sections with different porosities or densities of the metal powder or to use different particle sizes of at least two metal powders. By means of different densities of the metal powder in different sections of the adjustment element, individual porosities can be set in the desired manner, depending on the given filter requirements with regard to passage cross sections in the filter structure. In a pressing area, e.g. a particularly high compression of the metal powder can be generated.

drawing

An embodiment of the invention is shown in simplified form in the drawing and explained in more detail in the following description. Show it 1 an axial section through a fuel injection valve according to the prior art, 2 an enlarged section of the in 1 shown fuel injection valve in the area II in 1 with an inventive embodiment of the adjustment and 3 the adjustment in a sectional view.

Description of the embodiments

Before using the 2 and 3 Embodiments of a fuel injection valve according to the invention will be described in more detail, is to better understand the invention first with reference to 1 an already known one Fuel injector with respect to its essential components will be explained briefly.

This in 1 illustrated fuel injector 1 is in the form of a fuel injector 1 designed for fuel injection systems of mixture-compression, spark-ignited internal combustion engines. The fuel injector 1 is particularly suitable for direct injection of fuel into a combustion chamber, not shown, of an internal combustion engine.

The fuel injector 1 consists of a nozzle body 2 in which a valve needle 3 is arranged. The valve needle 3 stands with a valve closing body 4 in operative connection with one on a valve seat body 5 arranged valve seat surface 6 cooperates to a sealing seat. In the fuel injection valve 1 In the exemplary embodiment, this is an inwardly opening fuel injection valve 1 which has at least one injection opening 7 features. The nozzle body 2 is through a seal 8th against an outer pole 9 a magnetic coil 10 sealed. The magnetic coil 10 is in a coil housing 11 encapsulated and placed on a coil carrier 12 wound, which at an inner pole 13 the solenoid 10 is applied. The inner pole 13 and the outer pole 9 are through a narrowing 26 separated from each other and each other by a non-ferromagnetic connecting member 29 connected. The magnetic coil 10 is over a line 19 from one via an electrical plug contact 17 energized electric current. The plug contact 17 is from a plastic casing 18 surrounded by the inner pole 13 can be injected.

The valve needle 3 is in a valve needle guide 14 guided, which is designed disk-shaped. For stroke adjustment is a paired shim 15 , Upstream of the dial 15 there is an anchor 20 , This is about a first flange 21 non-positively with the valve needle 3 in connection, which by a weld 22 with the first flange 21 connected is. On the first flange 21 a return spring is supported 23 from, which in the present design of the fuel injection valve 1 through an adjusting sleeve 24 is brought to bias.

In the upper valve needle guide 14 , in anchor 20 and on a lower guide element 36 run fuel channels 30 . 31 and 32 , The fuel is supplied via a central fuel supply 16 fed and through a filter element 25 filtered. The fuel injector 1 is through a seal 28 against a fuel distribution line, not shown, and through another seal 37 sealed against a cylinder head, not shown. Between the first flange 21 and the anchor 20 is a forward stroke spring 38 arranged the anchor 20 in the idle state of the fuel injection valve 1 in abutment with the second flange 34 holds. The spring constant of the forward stroke spring 38 is much smaller than the spring constant of the return spring 23 ,

At rest of the fuel injection valve 1 becomes the anchor 20 from the return spring 23 and the Vorhubfeder 38 contrary to its stroke direction so acted upon, that the valve closing body 4 on the valve seat surface 6 is held in sealing contact. Upon energization of the solenoid 10 builds up this a magnetic field, which is the anchor 20 initially against the spring force of the Vorhubfeder 38 moved in the stroke direction, wherein a Ankerfreiweg by the distance between the first flange 21 and the anchor 20 is predetermined. After passing through the anchor freeway, the anchor decreases 20 the first flange 21 , which with the valve needle 3 is welded, against the spring force of the return spring 23 also in the stroke direction with. The anchor 20 goes through a total stroke, the height of the working gap 27 between the anchor 20 and the inner pole 13 equivalent. The with the valve needle 3 related valve closing bodies 4 lifts from the valve seat surface 6 off, and the over the fuel channels 30 to 32 Guided fuel is through the spray opening 7 hosed.

If the coil current is switched off, the armature drops 20 after sufficient degradation of the magnetic field by the pressure of the return spring 23 from the inner pole 13 which causes the valve needle 3 related first flange 21 moved against the stroke direction. The valve needle 3 is thereby moved in the same direction, whereby the valve closing body 4 on the valve seat surface 6 touches down and the fuel injector 1 is closed. The Vorhubfeder 38 impinges on the anchor 20 then again so that this is not from the second flange 34 rebounds, but returns to the idle state without Anschlagspreller.

The inner pole 13 is to the inlet end of the fuel injection valve 1 designed sleeve-shaped and thus forms a connection sleeve in this area 40 , The connection sleeve 40 Can also be used as a separate component independent of the inner pole 13 be formed in the then, for example, the inner pole 13 is fitted. In the area of the connection sleeve 40 is the filter element 25 introduced, which serves to filter out such particles in the fuel, which could otherwise lead to functional impairment of the relevant valve components such as the sealing seat.

The electromagnetic circuit may e.g. be replaced by a piezoelectric actuator or a magnetostrictive actuator as an actuator.

2 shows in a partial axial sectional view of the in 1 With II designated section as an inventive embodiment of a setting 50 , which is designed as a combined component and at least the functions of the adjusting sleeve 24 and the filter element 25 united. In contrast to known metal rolled, bent or machined setting sleeves is the adjustment element according to the invention 50 built up of a sintered metal powder. Ideally, the adjusting element 50 produced by a sintering process or a MIM (Metal Injection Molding) process. To the pressing area 55 of the adjusting element 50 to ensure the metal powder in a range, for example in the region of the inflow end of the adjustment 50 , with the largest diameter of the adjusting element 50 is executed, highly compressed.

3 shows the adjusting element according to the invention 50 as a single component in a sectional view.

The filter element is in the adjustment 50 directly integrated. The filtering function is provided by the porous structure of the adjusting element made by sintering 50 generated. The filter structure 52 is in an axially central region of the adjustment 50 provided in which the metal powder is less highly compressed in the sintering process. By different densities of the metal powder in different sections of the adjustment 50 Individual porosities can be set in the desired manner, depending on the given filter requirements with regard to passage cross sections in the filter structure 52 , In addition, metal powder for one and the same adjustment 50 can be used, which are characterized in individual sections by different particle sizes. The porosity can be in the range of the filter structure 52 be chosen so that the function of throttling the fuel flow is integrated with. Alternatively, however, can also over the entire adjustment 50 an identical porosity in the sintered metal powder are produced, which is particularly easy to produce in terms of manufacturing technology. Then, in a sense, the entire adjustment would be 50 allow the filter function.

Particularly in the case of high-pressure injection valves, which are supplied, for example, with a fuel pressure of> 100 bar, it has been shown that during operation a considerable noise development occurs, which can be perceived as partly disturbing. An effective noise reduction takes place in that in the filter structure 52 the flow areas take on a throttle function, since they have an opening cross section which is smaller by a multiple than the opening cross section of the connection sleeve 40 or the inner pole 13 , With the help of the filter structure 52 can be done so a targeted damping of pressure pulsations inside the fuel injection valve. In addition to the filter structure 52 solely due to the porous structure can in the filter section of the adjustment 50 also bores through other manufacturing processes, such as laser drilling, introduced. Even then, the integration of the throttle function in such a filter structure 52 possible.

In a press area 55 opposite region at the downstream end of the adjustment 50 If, for example, a diameter-reduced portion is provided which serves as a pin-like spring guide section 53 the leadership of the return spring 23 serves as the 2 can be clearly seen. In this case, the return spring is supported 23 at a radial shoulder 54 of the adjusting element 50 while the pin-like spring guide section 53 in the upper turns of the return spring 23 engages and slipping of the return spring 23 prevented. During the assembly process, the adjustment is 50 in the inner pole 13 guided, wherein the return spring 23 is set to a Voreinpressmaß. After this assembly and the welding of the connection sleeve 40 at the inner pole 13 can finally by moving the adjustment 50 the dynamic spray rate and the spring force of the return spring 23 finally fixed. As already mentioned above, also the spring guide section 53 with appropriate porosity take over the filter function.

The invention is not limited to the illustrated embodiments and also in a variety of other designs of fuel injection valves compared to those in 1 shown design of the fuel injection valve feasible.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 4003228 A1 [0002]
• US 5335863 A [0003]
• US Pat. No. 6,448,422 B1 [0003]
• EP 1296057 B1 [0003]
• EP 2426351 A1 [0003]
• EP 1377747 A1 [0003]

Claims (10)

Fuel Injector ( 1 ) for fuel injection systems of internal combustion engines, in particular for the direct injection of fuel into the combustion chamber of an internal combustion engine, with an actuator ( 9 . 10 . 13 . 20 ), by the excitation of which a lifting movement of a valve needle ( 3 ) is achieved, whereby an actuation of a valve closing body ( 4 ), which together with a valve seat surface ( 6 ) forms a sealing seat is possible, and with an inlet-side fuel supply ( 16 ), wherein in the fuel feed an adjusting element ( 50 ) for adjusting the spring force of a return spring ( 23 ), characterized in that the adjusting element ( 50 ) consists of a sintered metal powder and has a porous structure ( 52 ) having. Fuel injection valve according to claim 1, characterized in that a filter element in the adjustment ( 50 ) is directly integrated. Fuel injection valve according to claim 2, characterized in that the filter function by the porous structure ( 52 ) of the adjusting element produced by sintering ( 50 ) is generated. Fuel injection valve according to claim 3, characterized in that the filter structure ( 52 ) in the filter section of the adjusting element ( 50 ) additionally bores, which are introduced by other manufacturing methods, such as laser drilling, has. Fuel injection valve according to claim 3 or 4, characterized in that the porosity or the opening cross sections in the region of the filter structure ( 52 ) are selected so that the function of throttling the fuel flow is integrated with. Fuel injection valve according to one of the preceding claims, characterized in that the adjusting element ( 50 ) a pressing area ( 55 ), which preferably in the region of a largest diameter of the adjusting element ( 50 ) lies. Fuel injection valve according to one of the preceding claims, characterized in that on the adjusting element ( 50 ) a spring guide section ( 53 ) is provided, the leadership of the return spring ( 23 ) serves. Fuel injection valve according to claim 7, characterized in that at the downstream end of the adjusting element ( 50 ) the spring guide section ( 53 ) is executed, in particular in the form of a pin. Fuel injection valve according to one of the preceding claims, characterized in that the adjusting element ( 50 ) has an identical porosity throughout. Fuel injection valve according to one of claims 1 to 8, characterized in that the adjusting element ( 50 ) has different porosities or densifications of the metal powder in at least two sections or different particle sizes of at least two metal powders are used.

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