DE102014225994A1 - 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 bounded outwardly by a thin-walled sleeve (51), and inside the sleeve (51), a dome-shaped filter element (62) made of a metal mesh and a throttle element (56) are inserted as separate inserts ,

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 region 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 the spring tension remains constant over the service life of the fuel injection valve, ie 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 a setting element 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 the fuel, damping of pressure pulsations) in itself, the adjustment of a Sleeve is formed to the outside, which receives two inserts in their interior and encloses them safely and protected.

With very low additional costs and also easy to produce is achieved by introducing a disc-shaped throttle element with an integrated throttle bore in the adjustment a significant noise reduction over fuel injectors similar design and comparable structural design.

Since a filter element is ideally integrated in the adjusting element, the highest conceivable functional integration is made on the adjusting element according to the invention. Advantageously, the filter element is brought from a metal fabric by deep drawing in a dome or dome contour, which is very precisely in the sleeve of the adjusting element can be fitted.

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

In addition to the attachment possibilities of the filter or the throttle element in the sleeve by means of material or non-positive joining method, it is particularly simple and inexpensive to run the sleeve so long that by means of a flange by overlapping the throttle element, both the throttle element and the filter element in the sleeve are secured.

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 an external view, 4 a cut-open adjustment according to 3 and 5 an alternative embodiment of an adjustment in a sectional view.

Description of the embodiments

Before using the 2 to 5 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 in 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 three parts. Thus, the outer sheath of the adjusting element forms 50 a metal sleeve 51 , which is executed eg several times stepped and by deep drawing is made. 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 63 of the adjusting element 50 , which is only slightly smaller in outer diameter than the pressing area 55 ,

In the deep-drawn sleeve 51 is a filter element 62 integrated, the dome or dome is executed and consists of a metal fabric. The metal mesh is designed so stiff that the dome filter as a filter element 62 is fixed immutable in its contouring. The filter element 62 has at its open end z. B. a larger diameter collar area, with the radially enlarged area 61 the sleeve 51 corresponds. The metal fabric of the domed or dome-like filter element 62 is for example made up of a Betamesh ^™ or square mesh or similar tissue structures. The dome or dome contour of the filter element 62 can be achieved eg by deep drawing.

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 in a separate insert, as a disc-shaped throttle element 56 is executed. The throttle element 56 is at least partially in the radially enlarged area 61 the thin-walled sleeve 51 accommodated. For safe absorption of the throttle element 56 is the sleeve 51 above the pressing area 55 conically protruding with a bulge 60 executed. As stated above, has the filter element 62 also a bulge 60 ' in the upper fret area, at the bulge 60 the sleeve 51 can be created from the inside.

Because the throttle element 56 At least in a portion itself is provided with a conical lateral surface, the throttle element 56 positive fit in the area of the bulges 60 . 60 ' of the radially enlarged area 61 the sleeve 51 or the filter element 62 be recorded. In addition, this connection area can be secured by a welded connection 69 in the form of a circumferential seam or several stapling points in the area of the bulges 60 . 60 ' is produced. The welded joint 69 can optionally by laser, roll, resistance welding o.ä. Joining methods are produced. The edge region of the throttle element 56 is sealed so far that a bypass to the throttle bore 54 is prevented. The throttle element 56 For example, has an inlet-side section 66 which is smaller in diameter than the region which is radially enlarged with the region 61 the sleeve 51 corresponds, and from the sleeve 51 protrudes. Alternatively to the conically projecting bulge 60 can the radially enlarged area 61 the sleeve 51 be cylindrical, so that in this case, the filter element 62 and the throttle element 56 have a cylindrical insertion area. A pressing is also conceivable as an alternative to welding.

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.

3 shows the adjustment 50 in an exterior view. Doing the training of the sleeve 51 clearly, seen over its axial length several areas 55 . 61 . 63 has, which have a different outer diameter. The throttle element 56 can be ideally a simple, precisely produced in outer and inner diameter disc with parallel end faces.

In 4 is the adjustment element 50 according to 3 shown in a sectional view. The throttle element 56 is designed disc-shaped and stepped and is the inlet side of the sleeve 51 about the bulge 60 the sleeve 51 out. The protruding pin-like section 66 has a significantly smaller outer diameter than the outer diameter of the inside of the sleeve 51 lying portion of the throttle element 56 , Also clear is the connection area of throttle element 56 , Filter element 62 and sleeve 51 , in each of which the conical flares 60 . 60 ' the sleeve 51 and the domed filter element 62 and the conical circumferential surface of the throttle element 56 such form-fitting correspond with each other that the filter element 62 between the sleeve 51 and the throttle element 56 securely and reliably fastened. The connection area between sleeve 51 , Filter element 62 and throttle element 56 is by means of a welded joint 69 additionally secured.

5 shows an alternative embodiment of a setting 50 in a sectional view. In this embodiment, the metal fabric of the domed or dome-like filter element 62 now on a frame part 65 made of injection-molded plastic, with the frame part 65 in the sleeve 51 is attached. The deep-drawn metal fabric of the filter element 62 is in the plastic frame part 65 with cast, leaving a one-piece filter element 62 present in the sleeve 51 can be introduced. The frame part 65 corresponds to the radially enlarged area 61 the sleeve 51 for safe and reliable attachment of the filter element 62 , The filter element 62 Can safely by a cohesive or non-positive joining process in the sleeve 51 be attached. Alternatively, as in 5 shown the sleeve 51 over the frame part 65 of the filter element 62 survive and also a lower part of the disc-shaped throttle element 56 with record and overlap for safe recording. This is the sleeve 51 with a throttle element 56 at least partially overlapping curl 68 Mistake. A sloping area 70 in the sleeve 51 at the lower end of the frame part 65 of the filter element 62 serves to increase the fatigue strength by a lower stress of the material during deep drawing.

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 (11)

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 ) of a sleeve ( 51 ) is limited to the outside and inside the sleeve ( 51 ) a domed or dome-like filter element ( 62 ) of a metal mesh and a throttle element ( 56 ) are introduced as each independent inserts. Fuel injection valve according to claim 1, characterized in that the sleeve ( 51 ) represents a thin-walled deep-drawn component. Fuel injection valve according to claim 1 or 2, characterized in that in the throttle element ( 56 ) 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 the throttle element ( 56 ) is disc-shaped. Fuel injection valve according to claim 4, characterized in that the throttle element ( 56 ) with a section ( 66 ) from the sleeve ( 51 ) stands out. Fuel injection valve according to one of the preceding claims, characterized in that the throttle element ( 56 ) on the inlet side in the sleeve ( 51 ) of the adjusting element ( 50 ) is introduced. 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 the domed or dome-like filter element ( 62 ) in the adjustment element ( 50 ) is inserted between the sleeve ( 51 ) and the throttle element ( 56 ) is attached. Fuel injection valve according to claim 8, characterized in that the connection area between the sleeve ( 51 ), Filter element ( 62 ) and throttle element ( 56 ) by means of a welded connection ( 69 ) is secured. Fuel injection valve according to one of claims 1 to 8, characterized in that the metal fabric of the domed or dome-like filter element ( 62 ) on a frame part ( 65 ) is mounted from injection-molded plastic, wherein the frame part ( 65 ) in the sleeve ( 51 ) is attached. Fuel injection valve according to one of the preceding claims, characterized in that the metal fabric of the domed or dome-like filter element ( 62 ) is constructed of a Betamesh ^™ or square mesh or similar tissue structures.

Images