DE102011078564A1 - Control valve for a fuel injector and fuel injector - Google Patents

Abstract

The invention relates to a control valve (10; 10a) for a fuel injector (1) with a valve piece (25; 25a) arranged in an injector housing (11) and a gastronormer (33) which can be actuated by an actuating element (43), preferably a magnet coil. which is axially movably guided and which presses with a closing force against a valve seat (30) formed on the valve piece (25; 25a), wherein a valve chamber (35) is formed between the magnet armature (33) and the valve piece (25; which is hydraulically connected via a drain hole (41) to a control chamber (20) for a nozzle needle, wherein the valve chamber (35) via the valve seat (30) in a low pressure space (21) is pressure relieved, and wherein the armature (33) in one The sleeve-shaped region (26), which is reduced in diameter, is surrounded by an annular element having at least one passage opening, through which fuel flows in the direction of the low-pressure space (21). According to the invention, the element is designed as a shielding element (50; 50a) not connected to the sleeve-shaped region (26) of the magnet armature (33) or the valve piece (25a), and in that the at least one passage opening (52 ) is formed as a throttle opening between the sleeve-shaped region (26) of the magnet armature (33) or the valve piece (25a) and the shielding element (50; 50a).

Description

State of the art

The invention relates to a control valve for a fuel injector according to the preamble of claim 1. Furthermore, the invention relates to a fuel injector with a control valve according to the invention.

Such a control valve is out of DE 10 2007 047 425 A1 the applicant known. The known control valve has a magnet armature whose valve seat facing, reduced in diameter end is surrounded by an annular guide member which guides the armature radially in its up and down movement. For this purpose, it is necessary that the guide element on the one hand has an axial mobility, and on the other hand in the radial direction a certain rigidity. The known from the cited document guide member is connected to the armature so that it can guide him in the up and down movement. In addition, passage openings are provided in the known, membrane-like guide member, can flow through the fuel with lifted off his seat armature from a control chamber and a drain hole in a valve piece in the direction of a low pressure space, from where the fuel enters the fuel return.

The passage openings provided in the known guide element are uniformly arranged in particular over the entire cross section of the guide element, such that the fuel can flow through the guide element in a direction parallel to the longitudinal axis of the control valve. With a relatively small distance between the armature plate having a magnet armature and the guide element has been found that by flowing through the passage openings of the fuel (axially) meets the armature plate and thus exerts an additional influence on the opening and closing speed of the armature. This influence is greater, the smaller the distance between the guide element and the anchor plate. This effect results in a non-linear course of the movement of the magnet armature over the actuation period of the control valve, which in turn can lead to a non-linear course in the quantity map (amount of the discharged control quantity over the actuation period of the control valve) of the fuel injector.

Disclosure of the invention

Based on the illustrated prior art, the invention has the object, a control valve for a fuel injector according to the preamble of claim 1 such that the influence of flowing through at least one passage fuel to the actuator, in particular the armature plate of the armature is reduced in order to allow a linear as possible of the movement of the armature. This object is achieved in a control valve for a fuel injector with the features of claim 1, characterized in that the formed in the prior art as a guide element for the armature element is formed as not connected to the armature shielding element for the fuel, and that the at least one Passage opening is formed as a throttle opening between the gas tanker or a valve member and the shielding. This makes it possible according to the invention to protect most of the (plate-shaped) region of the armature from the direct impact of the fuel as it flows through the passage opening, whereby the non-linear effects of the flow through the at least one passage opening are reduced.

Advantageous developments of the control valve according to the invention are specified in the subclaims. All combinations of at least two of the features disclosed in the claims, the description and / or the figures fall within the scope of the invention.

In the simplest structural design of the at least one passage opening, this is formed as an annular gap. As a result, a particularly simple producibility of the shielding element and a relatively large flow cross section for the outflowing fuel are achieved.

In order to generate as large as possible a flow cross section for the fuel flowing through the shielding element, it is additionally or alternatively also possible for the at least one passage opening to be oblique with respect to the longitudinal axis of the control valve, so that the fuel flowing through the at least one passage opening forms a having radial flow component. In this case, the larger the radial flow component, the lower the influence of the fuel flowing through on the armature plate of the magnet armature, i. the more obliquely the at least one passage opening is arranged with respect to the longitudinal axis of the control valve.

Alternatively or additionally, it is also possible for the at least one passage opening to be aligned in alignment with the flow gap formed between the magnet armature and a housing part. This also reduces or prevents a direct onflow of the magnet armature.

Alternatively, however, it is also possible that the addressed housing part forms an undercut, and that the at least one passage opening is arranged in alignment with the undercut. This means that the fuel flowing through the shielding element first impinges on the housing part in the region of the undercut, before it can impinge on the magnet armature.

Very particularly preferably in all variants, it is provided that several, preferably arranged at equal angular intervals passage openings are provided. As a result, as a whole, a particularly large flow cross-section is produced for the fuel, so that the flow velocity or the movement impulse of the fuel to the magnet armature is relatively low.

In order to always allow a targeted alignment of the passage openings even with pressure fluctuations, it is furthermore preferably provided that the shielding element consists of a rigid material.

The shielding is particularly easy and easy to assemble when it is clamped axially between the valve body or the injector and a magnet armature surrounding the housing part.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing.

This shows in:

1 a longitudinal section through a fuel injector in the region of a control valve according to the invention and

2 a section of the control valve according to 1 at one opposite the 1 modified embodiment of the control valve, also in longitudinal section.

The same components or components with the same function are provided in the figures with the same reference numerals.

In the figures is a section of a fuel injector 1 illustrated as it serves in particular as part of a so-called common rail system for injecting fuel into a combustion chamber, not shown, of a self-igniting internal combustion engine. The fuel injector 1 has in the illustrated section a control valve according to the invention 10 on that in an injector housing 11 of the fuel injector 1 is used. In the 1 one recognizes further a valve body 12 , a nozzle needle piston 13 a nozzle needle, not shown, an electromagnetic actuator 14 and a housing part 15 for the actuator 14 , The control valve 10 and the electromagnetic actuator 14 form a servo-valve for the fuel injector 1 out.

The valve body 12 includes a flange portion 18 and a guide section 19 for the axial guidance of the nozzle needle piston 13 , The valve body 12 is with the flange section 18 in the injector housing 11 hydraulically tight and separates a low pressure chamber 21 from a high pressure room 22 , The high pressure room 22 is via a high pressure bore 23 Fuel from a fuel storage (common rail) supplied to the diesel injector. In the leadership section 19 is a tax room 20 formed, which the nozzle needle piston 13 is exposed to a pressure surface. From the high pressure room 22 leads an inlet bore 24 with an inlet throttle in the control room 20 ,

The control valve 10 includes one on the flange portion 18 trained valve piece 25 , a valve sleeve 26 , a guide pin 27 and a valve spring 28 , At the valve piece 25 is a valve seat 30 formed with one on the valve sleeve 26 trained sealing edge 31 interacts and a valve chamber 35 from the low pressure room 21 separates. The valve sleeve 26 also has a guide bore 32 and a plate-shaped magnet armature 33 on top of an anchor plate 34 having. The valve sleeve 26 is with the guide hole 32 on the guide pin 27 guided axially movable. The valve chamber 35 will continue from an end face of the guide pin 27 limited. The guide pin 27 lies with his the valve chamber 35 remote end face at one with the housing part 15 connected support plate 39 at. The valve chamber 35 is over a drain hole 41 with a drain throttle 42 with the control room 20 hydraulically connected.

The actuator 14 includes a magnetic coil 43 and a magnetic core 44 , where the magnetic core 44 in the housing part 15 is fixed. For this purpose, in the illustrated embodiment, a clamping ring 45 provided by means of the support plate 39 the magnetic core 44 in the housing part 15 fixed.

According to the invention it is provided that the valve sleeve 26 at the tanker 33 in the area near the valve piece 25 from a shielding element 50 is surrounded radially. The particular of a rigid material, preferably made of metal, existing shielding 50 is in the illustrated embodiment axially between the housing part 15 and the flange portion 18 clamped.

Alternatively, however, it is also conceivable that the shielding element 50 between the injector 11 and the housing part 15 is axially clamped.

Between the shielding element 50 and the valve sleeve 26 is an annular flow gap 51 formed by the fuel from the control room 20 , the drain hole 41 , the valve chamber 35 and the sealing edge 31 in the low pressure room 22 on the control room 20 opposite side of the shielding 50 can flow out. The shielding element 50 is with the valve sleeve 26 not connected. The flow gap 51 thus forms a passage opening 52 in the form of a throttle opening for the fuel, such that most of the cross-sectional area of the armature plate 34 of the magnet armature 33 is not directly flowed by the flowing fuel.

In the 2 is a modified control valve 10a shown. At the control valve 10a the guide pin protrudes 27a with his the control room 20 facing side into the drain hole 41 into it. Furthermore, the valve sleeve 26 in diameter formed such that they are flush with the radially elongated valve piece 25a in which is integral with the valve body 12 connected valve piece 25a Passage openings 58 are designed for fuel. Furthermore, it can be seen that the housing part 15a on the control room 20 opposite side of the shielding 50a a cone-shaped surface 53 has, so that between the shielding 50a and the area 53 an undercut 54 is trained. The housing part 15a furthermore has a radially inner web-shaped wall section 55 on, between the magnet and the armature 33 a flow-through gap 56 is designed for the fuel.

The shielding element 50a includes next to the flow gap 51 In addition, further passage openings 52a respectively. 52b , wherein the one passage openings 52a exemplary in alignment with the longitudinal axis 57 of the control valve 10a are aligned, such that these with the flow-through gap 56 are aligned. In contrast, the passage openings 52b in relation to the longitudinal axis 57 arranged at an oblique angle, such that the pressure medium when flowing through the passage openings 52b in the area of the undercut 54 before it then crosses the flow gap 56 the area of the magnet armature 33 happens. The through the passage opening 52b flowing fuel thus has a radial flow component. For the sake of simplicity, in the 2 only one passage opening in each case 52a . 52b shown.

It is preferably provided that a plurality of passage openings 52a . 52b (either passages 52a or 52b , or a combination of the passage openings 52a . 52b ), preferably at equal angular intervals from one another in the region of the shielding element 50a are arranged. By the orientation or arrangement of the passage openings 52a . 52b becomes a direct impact of the shielding 50a flowing fuel on the armature 33 prevented.

The control valve described so far 10 . 10a as well as the fuel injector 1 can be modified or modified in many ways without departing from the spirit of the invention.

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 102007047425 A1 [0002]

Claims (10)

Control valve ( 10 ; 10a ) for a fuel injector ( 1 ), with one in an injector housing ( 11 ) arranged valve piece ( 25 ; 25a ) and one of a magnetic coil ( 43 ) actuatable magnetic tanker ( 33 ), which is guided axially movable, and with a closing force against one on the valve piece ( 25 ; 25a ) formed valve seat ( 30 ), between the magnet armature ( 33 ) and the valve piece ( 25 ; 25a ) a valve chamber ( 35 ) is formed, which via a drain hole ( 41 ) with a control room ( 20 ) is hydraulically connected to a nozzle needle, wherein the valve chamber ( 35 ) over the valve seat ( 30 ) into a low-pressure space ( 21 ) is pressure relieved, and wherein the magnet armature ( 33 ) in a reduced diameter, sleeve-shaped region ( 26 ) of an annular, at least one passage opening ( 52 ) is surrounded by the fuel from the valve chamber ( 35 ) in the direction of the low-pressure space ( 21 ) flows off, characterized in that the element as a with the sleeve-shaped area ( 26 ) of the magnet armature ( 33 ) not connected shielding element ( 50 ) is formed for the fuel, and that the at least one passage opening ( 52 ) as a throttle opening between the sleeve-shaped region ( 26 ) of the magnet armature ( 33 ) and the shielding element ( 50 ) is formed, or that the element as one with the valve piece ( 25a ) not connected shielding element ( 50a ) is formed for the fuel, and that the at least one passage opening ( 52 ) as a throttle opening between the valve piece ( 25a ) and the shielding element ( 50a ) is trained. Control valve according to claim 1, characterized in that the at least one passage opening ( 52 ) is designed as an annular gap. Control valve according to claim 1 or 2, characterized in that the at least one passage opening ( 52b ) in relation to the longitudinal axis ( 57 ) of the control valve ( 10a ) is preferably arranged obliquely, so that through the at least one passage opening ( 52b ) flowing fuel has a radial flow component. Control valve according to one of claims 1 to 3, characterized in that the at least one passage opening ( 52a ) in alignment with one between the armature ( 33 ) and a housing part ( 15a ) formed flow gap ( 56 ) is arranged. Control valve according to one of claims 1 to 3, characterized in that a housing part ( 15a ) an undercut ( 54 ) is formed, and that the at least one passage opening ( 52b ) in alignment with the undercut ( 54 ) is arranged. Control valve according to one of claims 3 to 5, characterized in that a plurality of, preferably at equal angular intervals arranged passage openings ( 52a ; 52b ) are provided. Control valve according to one of claims 1 to 6, characterized in that the shielding element ( 50 50a ) consists of a rigid material. Control valve according to one of claims 1 to 7, characterized in that the shielding element ( 50 ; 50a ) between a valve body ( 12 ) or the injector housing ( 11 ) and a magnet armature ( 33 ) radially surrounding housing part ( 15 ; 15a ) is axially clamped. Control valve according to one of claims 1 to 8, characterized in that the magnet armature ( 33 ) an anchor plate ( 34 ) having. Fuel injector ( 1 ) with a control valve ( 10 ; 10a ) according to one of claims 1 to 9.

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