DE102013225840A1 - 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) is provided with a securing means (65) for the return spring (23) in such a way that the return spring (23) on the adjusting element (50) can be pre-assembled in the fuel injection valve (1) before it is mounted.

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, spring guidance and centering, filtering of the fuel, damping of pressure pulsations) in itself, wherein the adjusting element is provided with a securing means for the return spring such that the return spring is pre-assembled on the adjusting before its installation in the fuel injection valve captive. In an advantageous manner, a structural unit for mounting in the fuel injection valve can be presented in which the return spring is already included. In this respect, the separate assembly process of introducing the return spring can be omitted here, which simplifies the manufacture of the fuel injection valve and makes it less expensive.

The securing means on the return spring facing the end of the adjustment can be configured very diverse, preferably the securing means is provided on a thin-walled sleeve which limits the adjustment to the outside and also provides in the latching also for a guide and centering of the return spring, since an extension of the sleeve in the axial direction has a certain necessary guide length.

In this respect, the spring guide and safety device can be integrated directly and particularly cost-effectively in the manufacture of the sleeve of the adjusting element without additional components being required. The cost of manufacturing the adjustment can be kept low in this way. The internal geometries of the inner pole and the connecting sleeve can be made simplified; the tolerance requirements can be lowered. The spring guide integrated on the adjusting element according to the invention also has the advantage that the wear in the inner pole bore is markedly reduced compared with spring guides arranged directly in the inner pole.

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

With very low additional costs and also easy to manufacture is achieved by introducing a throttle bore in the adjustment a significant reduction in noise compared to fuel injectors similar design and comparable structural design achievable.

In an ideal manner, a filter element is additionally arranged in the adjusting element, so that the highest conceivable functional integration is made on the adjusting element according to the invention.

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 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 embodiment of the adjusting element according to the invention, 3 the adjusting element in a sectional view and 4 an adjustment with a pre-assembled return spring in a sectional view.

Description of the embodiments

Before using the 2 to 4 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 fuel injection valve will be briefly explained with respect to its essential components.

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. The adjustment element 50 consists of several individual parts. Thus, the outer sheath of the adjusting element forms 50 a metal sleeve 51 , which, for example, is multi-stepped and manufactured by deep drawing. The thin-walled sleeve 51 In this case, for example, has a radially enlarged area in an inlet-side section 61 on, the diameter-largest portion of the adjusting element 50 represents. In the axial direction, this is followed by a smaller-diameter area, which acts as a pressing area 55 serves. The axially succeeding downstream portion is the smallest diameter portion 62 of the adjusting element 50 , which is only slightly smaller in outer diameter than the pressing area 55 ,

In the deep-drawn sleeve 51 there is a sieve basket made of plastic 53 which forms the main body of an integrated filter. The plastic of the strainer basket 53 is preferably an organic polymeric high temperature resistant thermoplastic such as polyether ether ketones (PEEK) or polyphenylene sulfide (PPS) or polyamides (PA) or polyphthalamides (PPA). Ideally, the strainer basket 53 produced by plastic injection molding. Inside the plastic base of the adjustment 50 is a filter fabric 52 introduced as a filter element, which can also be inserted in the plastic injection molding process as an insert in the tool. This hose-like filter fabric 52 can be made of PEEK or preferably made of a metallic fabric material, which provides additional support and increased robustness of the screen basket 53 provides. The sieve basket 53 of the filter has an upper diameter enlarged receiving area 58 in a suitably form-fitting manner in the radially enlarged area 61 the sleeve 51 can be used, allowing slippage of the strainer basket 53 inside the sleeve 51 is excluded. Also about the other areas 55 . 62 fills the screen basket 53 the inside of the sleeve 51 largely off, with the screen basket 53 at its downstream end at a floor area 59 the sleeve 51 support, but also, as in 2 shown, can hang freely. The sieve basket 53 is formed by several, at least two web-like support parts of the filter body.

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 inlet region of the adjustment 50 a throttle bore 54 is provided, which has 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 , The throttle bore 54 has, for example, a diameter of 0.4 mm to 1.5 mm, depending on the opening width of the connection sleeve 40 , With the help of the throttle bore 54 a targeted damping of pressure pulsations in the interior of the fuel injection valve can take place. The throttle bore 54 is introduced, for example, in a separate insert, the disc-shaped throttle element 56 is executed and on the screen basket 53 is placed on the inlet side end side. For safe absorption of the throttle element 56 is the sleeve 51 above the throttle element 56 crimped. The throttle element 56 gets so tight sitting in the sleeve 51 introduced, that the edge region is sealed so far that a bypass to the throttle bore 54 is prevented.

According to the invention, the adjusting element 50 at its downstream end so with a securing means 65 for the return spring 23 provided that the return spring 23 on the adjusting element 50 before its installation in the fuel injection valve 1 is captive pre-assembled. The area around the securing means 65 also serves as a spring guide portion for the return spring 23 ,

3 shows an inventive adjustment 50 in which at the downstream end a securing means 65 for the return spring 23 is formed. The lower, downstream end of the adjustment 50 gets off the floor area 59 the deep-drawn sleeve 51 educated. The floor area 59 runs largely at right angles to the longitudinal extension of the adjustment 50 , However, the sleeve is 51 in the radially inner portion of the floor area 59 with a cone-like extension 60 towards the return spring 23 provided, ie axially beyond the otherwise flat floor area 59 survives and forms a spring guide section. The extension 60 However, it does not run as a cylindrical sleeve with a constant diameter, but has a central bulge 66 over which at least the upper turn of the return spring 23 is pushed away for latching.

4 shows an adjustment 50 with a pre-assembled return spring 23 in a sectional view. The return spring 23 lies with its upper end to the flat bottom area 59 at and over at least with their upper turn the bulge 66 , whereby a spring guide or Federzentrierung from the inside and a captive attachment of the return spring 23 on the adjusting element 50 are guaranteed to provide a pre-assembled unit. The extension 60 is designed in the axial direction so long that the return spring 23 is penetrated radially inwardly over a certain guide length.

In the assembly of the fuel injection valve 1 becomes the adjustment element 50 installed as the last component in the upstream module. Advantageously, while the return spring 23 due to their fixation directly together with the adjustment 50 inserted. During the assembly process the adjustment element becomes 50 in the inner pole 13 led, in which case ultimately over the pressing area 55 the return spring 23 is set to a desired Preeinpressmaß. When installing the connection sleeve 40 becomes the connection sleeve 40 beyond the protruding upper end of the adjustment 50 plugged. 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.

The captive locking of the return spring 23 on the adjusting element 50 for pre-assembly can be used instead of bulging 66 also with other security funds 65 at the return spring 23 facing the end of the adjustment 50 will be realized. Thus, bead-like thickening, latching hooks, latching noses or barb-like geometries are used as securing means 65 also at the bottom of the adjustment 50 conformable.

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 ) in such a way with a securing means ( 65 ) for the return spring ( 23 ) is provided that the return spring ( 23 ) on the adjusting element ( 50 ) before its mounting in the fuel injection valve ( 1 ) is captive pre-assembled. Fuel injection valve according to claim 1, characterized in that the securing means ( 65 ) on one of the adjusting element ( 50 ) outwardly terminating sleeve ( 51 ) is formed. Fuel injection valve according to claim 2, characterized in that the sleeve ( 51 ) represents a thin-walled deep-drawn component. Fuel injection valve according to claim 2 or 3, characterized in that from a downstream side floor area ( 59 ) of the sleeve ( 51 ) starting an extension ( 60 ) is provided, via which the return spring ( 23 ) can be pushed. Fuel injection valve according to claim 4, characterized in that on the extension ( 60 ) of the sleeve ( 51 ) the securing means ( 65 ) is formed. Fuel injection valve according to claim 5, characterized in that the extension ( 60 ) of the sleeve ( 51 ) a bulge ( 66 ) provided by the return spring ( 23 ) is overlapped with at least its upper turn. Fuel injection valve according to one of claims 1 to 5, characterized in that bead-like thickening, latching hooks, latching noses or barb-like geometries as securing means ( 65 ) on the return spring ( 23 ) facing the end of the adjusting element ( 50 ) are formed. Fuel injection valve according to one of the preceding claims, characterized in that the sleeve ( 51 ) seen over its axial length several areas ( 55 . 61 . 62 ), which have a different outer diameter. Fuel injection valve according to one of the preceding claims, characterized in that in the adjusting element ( 50 ) a flow restrictor in the form of a throttle bore ( 54 ) is provided, which has an opening cross section which is smaller by a multiple than the opening cross section of the fuel supply ( 16 ). Fuel injection valve according to one of the preceding claims, characterized in that in the adjusting element ( 50 ) a filter element ( 52 . 53 ) is provided.

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