DE102008001822A1 - Solenoid valve with anchor slot - Google Patents

Abstract

The invention relates to a fuel injector (10) for injecting fuel into the combustion chamber of an internal combustion engine, wherein an injection valve member (32) is actuated via a pressure relief of a control chamber (40). The storage space (40) is acted upon by fuel under system pressure. A pressure relief of the control chamber (40) via a switching valve (24), the valve member (44) opens or closes a valve seat (42). An armature assembly of the switching valve (24) comprises an armature plate (44) in which a number of recesses (76) designed as straight slots are made.

Description

State of the art

An injector for injecting fuel into the combustion chamber of an internal combustion engine, in which an injection valve member is actuated via a solenoid-operated control valve, is off EP-A 1 612 403 known. With the help of the control valve, an outlet throttle from a control room in the fuel return can be closed or released. The control chamber is bounded on one side by a control piston, with which an injection valve member is actuated, which releases or closes at least one injection opening into the combustion chamber of the internal combustion engine. The outlet throttle is received in a body, which is provided on the side facing away from the control chamber with a tapered valve seat. In this valve seat, a closing element is adjustable, which is connected to the armature of the solenoid valve. For this purpose, an edge is formed on the closing element, which is provided against a conically shaped seat. The closing element moves on an axial rod, which is integrally connected to the body in which the drainage throttle is formed. In order for the valve to close tightly, it is necessary to produce high-precision surfaces and to provide a highly accurate fit of the closure member to prevent the closure member from tilting, thereby failing to fully close the seat and causing pressure loss and leakage.

at for example on high-pressure accumulator injection systems (common rail) used fuel injectors can stroke-controlled Injectors are used, which by means of a solenoid valve for control of the pressure to be operated in a control room. The preferred needle-shaped injection valve member is for Example controlled via a servo control room. The pressure in the control room is via the solenoid valve, which is a spherical Closing element has controlled. The solenoid valve is usually not pressure balanced and therefore needed high spring forces, high magnetic switching forces and one due to the dimensioning of spring and magnet considerably increased space. Disadvantage with solenoid valves, which have a ball as closing element is the circumstance that severely restricted the sequence of Multiple injections exist, so that usually very short consecutive injection intervals not realized can be.

to Introduction of fuel into direct injection internal combustion engines, in particular self-igniting internal combustion engines currently increasingly used stroke-controlled common rail injection systems. The advantage of these systems is the fact that the injection pressure be adapted to the load and speed of the internal combustion engine can. Hubgesteuerte fuel injectors are known a solenoid valve can be actuated. The injection valve member is over controlled by a servo control room. The pressure in the control chamber of the fuel injector in turn is controlled by a solenoid valve. For improved injector tuning requires a solenoid valve which shortest possible switching times, therefore high switching speeds having. The use of a pressure balanced trained piston valve allows small spring forces, smaller magnetic forces, which are to be generated by the electromagnet and smaller valve strokes and thus shorter switching times. By the shorter ones Valve switching times can be the injection performance, especially the Multiple injection capability of the fuel injector improved become.

Presentation of the invention

Of the Invention is based on the object, a valve, in particular a To provide solenoid valve, which realizes very short switching times.

According to the invention a solenoid valve proposed, the armature assembly in particular a Anchor plate which is de-throttled in the edge region and recesses or openings that accelerate the movement allow the armature plate of the armature assembly by the fuel. Through the recesses, in an advantageous way than straight slots alternating in different lengths along the circumference may be formed, or as holes in the anchor plate are executed, the damping forces, d. H. the flow forces occurring during the movement, which move to the anchor plate and slow it down, reduced become. As a result, fast switching movements of the anchor plate are the Armature assembly possible.

In the hitherto usually a flat anchor plate without perforations having armature assemblies occur eddy currents that limit the speed of Magnetkraftaufbau and the magnetic force reduction. The eddy current losses can also be counteracted by the proposed solution according to the invention by attaching in the edge region of the anchor plate, in particular straight slots, which are executed in an alternating sequence in a shorter or longer length. By this solution, the relatively large area of the armature plate, which must be moved in the fuel, particularly well dethrottled without causing further loss of magnetic force by reducing the area at the inner pole of the electromagnet. A straight slit of the anchor plate reduces the damping of their movement in the force Substance fluid already considerable and also contributes to the reduction of eddy currents. Furthermore, a straight slit can be manufactured extremely cost-effectively.

alternative to those preferably in alternating sequence along the circumference of Anchor plate formed straight long slots, would be also a combination of short slots and additional openings, For example, holes in the faces of the anchor plate advantageous. Particularly advantageous is an anchor geometry with straight Slits in a fast-switching, especially pressure-balanced trained valve is used, as by this measure the valve speed, d. H. the switching speed of the armature between Valve seat and top stop is further increased. The According to the invention proposed anchor geometry However, even with not pressure balanced trained switching valves be used for other purposes.

Brief description of the drawings

Based In the drawings, the invention will be described below in more detail.

It shows:

1 a longitudinal section through the inventively proposed fuel injector with solenoid valve,

2 a plan view of a first embodiment of an anchor plate and

3 a plan view of a second embodiment of the anchor plate of the solenoid valve.

embodiments

From the illustration according to 1 is a longitudinal section through an inventively designed fuel injector out.

A fuel injector 10 is via a pressure accumulator 12 , in which there is a system pressure, fueled. The admission of pressure accumulator 12 (Common Rail) can be done by a high-pressure pumping unit, such as a high pressure pump of a high-pressure accumulator injection system, which in the illustration 1 not shown. One from the accumulator 12 to the fuel injector 10 extending high pressure line 14 opens into an injector body 16 in which there is a storage volume 18 located. The fuel injector 10 includes next to the injector body 16 a nozzle body 20 and an actuator housing 22 , In the actuator housing 22 is a fast switching switching valve 24 housed, which in the embodiment of the fuel injector 10 according to 1 is designed as a solenoid valve. Designed as a solenoid valve switching valve 24 includes a magnetic core 26 into which a magnetic coil 28 is embedded. Furthermore, it is located in the magnetic core 26 a through hole, in which, embedded in a sleeve 52 , a closing spring 54 is inserted, which is a valve member 44 of the switching valve 24 acted upon in the closing direction.

That in the injector body 16 trained storage volume 18 serves to damp hydraulic vibrations between the pressure accumulator 12 and the fuel injector 10 , Furthermore, the fuel injector includes 10 a valve piece 30 which is a control room 34 limited. The control room 34 is via an inlet throttle 36 with the storage volume 18 connected and is via the inlet throttle 36 with under system pressure, in the storage volume 18 stockpiled fuel. A pressure relief of the control room 34 takes place via a drainage channel 40 , in which at least one outlet throttle 38 is trained. The drainage channel 40 opens below a valve seat 42 , which in the representation according to 1 through the valve member 44 closed is. In the simplest case, the valve seat 42 in the plane of the valve piece 30 designed as a flat seat.

By pressure relief of the control room 34 the actuation of a preferably needle-shaped injection valve member takes place 32 , At this there is a circumferential collar, which is a closing spring 66 supported. The closing spring 66 , which is the preferred needle-shaped injection valve member 32 in his seat 72 on the other hand, is supported on a lower annular surface of the valve piece 30 from.

As shown in the illustration 1 further shows, is the preferred needle-shaped injection valve member 32 also in the nozzle body 20 guided. In the area of the guide of the injection valve member 32 in the nozzle body 20 are located on the lateral surface of the preferably needle-shaped injection valve member 32 one or more cuts 68 , Fuel that is under system pressure flows out of the storage volume via these 18 in an annulus 70 and stands at the seat 72 at. Im in 1 To stand is the preferred needle-shaped injection valve member 32 in his seat 72 put, so that injection openings 74 , which at the combustion chamber end of the fuel injector 10 are executed, remain closed.

For completeness, it should be mentioned that in the fuel injector 10 according to the execution in 1 the switching valve 24 an armature assembly operated. The armature assembly includes an armature plate 46 at which the valve member 44 is executed. The valve member 44 is in an anchor guide 48 guided. The anchor guide 48 lies on the upper plane of the valve piece 30 on. The anchor guide 48 and the valve piece 30 be over a valve clamping nut 50 to a shoulder of the injector body 16 hired and fixed there. The valve clamping nut 50 has a threaded portion, which in the illustration according to 1 with a corresponding thread on the inside of the actuator housing 22 is screwed. The valve member 44 , at the upper end of the anchor plate 46 is formed on a pressure pin 62 guided, so that the switching valve 24 pressure balanced. This allows smaller spring forces in the closing direction on the valve seat 42 work, realize; On the other hand, smaller magnetic forces for actuating a pressure-balanced executed switching valve 24 possible. This, in turn, allows for smaller valve lifts and faster shift times, which increase the multiple injection capability of the fuel injector proposed by the present invention 10 significantly favor. On the other hand, there is also the possibility of a conventional switching valve 24 use.

In addition, the anchor guide allows 48 a precise guidance of the valve member 44 , so that the exact impact of the valve member 44 in the valve seat 42 is guaranteed.

The pressure pin 62 has substantially the same diameter as the valve seat 42 on to pressure forces on the valve member 44 so that it is pressure balanced.

When controlling the solenoid 28 the anchor plate moves 46 together with the valve member 44 in the opening direction upwards. This results in a pressure relief of the control room 34 such that the preferably needle-shaped injection valve member 32 retracts into these and out of his seat 72 extending. From the storage volume 18 flows over the at least one polished section 68 on the lateral surface of the injection valve member 32 and the annulus 70 Pressurized fuel to the open injection ports 74 to. The fuel under system pressure is injected into the combustion chamber of the internal combustion engine.

To end the injection process, the energization of the solenoid 28 completed. Due to the effect of the closing spring 54 becomes the valve member 44 in the valve seat 42 ge represents and the pressure relief of the control room 34 over the drainage channel 40 with outlet throttle 38 prevented. About the inlet throttle 36 builds in the control room 34 System pressure, which on the upper face of the injection valve member 32 works and this in the seat 72 so that the combustion chamber side injection openings 74 are closed and the injection is terminated.

According to the invention, the anchor plate 46 the armature assembly of the switching valve 24 equipped so that they have the lowest possible flow resistance during their movement in the actuator chamber 58 and a high magnetic force can be generated, which allows fast closing movements. The anchor plate 46 is provided with recesses or openings, which rapid switching movements of the switching valve 24 enable and minimize the occurrence of eddy currents.

2 shows a first embodiment of the armature plate of the switching valve as shown in FIG 1 ,

As shown in the illustration 2 is removable, has a plane surface 84 the anchor plate 46 cutouts 76 in the embodiment according to 2 are formed as straight slots. The recesses formed as straight slots 76 in the anchor plate 84 run as shown in 2 in different lengths. reference numeral 78 denotes a first length of the recesses made as straight slots 76 while a second length thereof by reference numerals 80 is designated. The first length 78 exceeds the second length 80 about twice. As 2 is further to be seen, is between the running as a straight slots recesses 76 first length 78 in slot form a 90 ° division 82 educated. This applies analogously to the division of the recesses designed as straight slots 76 second length 80 , which is also in the plane area 84 the anchor plate 46 are formed in 90 ° division.

Through the geometry of the plane surface 84 the anchor plate 46 The eddy current losses and the damping forces can be considerably reduced. Advantageously, straight slots are formed - as in 2 shown - in the plane surface 84 the anchor plate 46 executed. These can be produced inexpensively and allow a strong reduction of the damping force with low loss of magnetic force. A particularly good vote is achieved by alternating long and short slots shown in alternating sequence, as by the first length 78 as well as the second length 80 the slot-shaped recesses 76 in 2 indicated. The embodiment according to 2 becomes the relatively large area in the outer area of the anchor plate 46 particularly well dethrottled, without a further loss of magnetic force occurs by a reduction of the surface at the inner pole.

The representation according to 3 is a wide one re embodiment of the design of the anchor plate refer. The representation according to 3 is a plane surface 84 removable, a combination of recesses made as straight slots 76 first length 80 each with intervening holes designed as holes 86 having. Also in the embodiment according to 3 can be a very high dethrottling of the large area in the outer area of the anchor plate 46 the armature assembly can be achieved, while a further loss of magnetic force can be reduced by reducing the area at the inner pole.

Particularly advantageous is the anchor geometry with slots, as shown in the illustration 2 shown in a fast-switching pressure-balanced switching valve 24 - as in 1 represented - because thereby the valve speed between upper stop and valve seat 42 can be increased. The inventively proposed switching valve 24 with the fast switching movements enabling anchor plate 46 , of course, can also be used with non-pressure compensated switching valves 24 be used.

In order to keep the manufacturing costs low, that is in the illustration according to 2 shown embodiment of only slots - but different length 78 . 80 - having plane surface 84 the anchor plate 46 preferable.

Also in the illustration according to 3 lies between the individual recesses designed as straight slots 76 first length 78 in the plane area 84 the anchor plate 46 a 90 ° division 82 in front. Of course it is possible in the plane surface 84 the individual recesses designed as straight slots 76 different lengths 78 . 80 also in one of a 90 ° division 82 deviating pitch to achieve a higher Entdrosselung in the outdoor area. This depends on the switching times to be achieved in multiple injections, where high demands on the switching speed of the switching valve 24 be put off.

The degree of Entschrosselung, by the proposed solution according to the invention, whether by recesses formed as a straight slots 76 different lengths 78 . 80 Be it through openings 86 in the plane area 84 , is reached, determines the switching speed of the switching valve 24 because the anchor plate 46 in the actuator room 58 on the low pressure side of the fuel injector 10 located, moved. In addition to the execution of the recesses 76 in the plane area 84 the anchor plate 46 As a rectangular, straight slots, this geometry can also be deviated, with an optimum between the Entdrosselung in the outer area and minimizing the magnetic force profile in the remaining interior of the plane 84 the anchor plate 46 the inner pole of the magnetic core opposite, is to strive.

The largest possible reduction of the plane surface 84 the anchor plate 46 in the outdoor area allows lower flow resistance during the movement of the anchor plate 46 in the low-pressure side actuator chamber 58 ,

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1612403 A [0001]

Claims (9)

Fuel injector ( 10 ) for injecting fuel into the combustion chamber of an internal combustion engine, wherein an injection valve member ( 32 ) via a pressure relief of a control room ( 40 ) is actuated, which is acted upon by a system pressure and the pressure relief of the control room ( 40 ) via a solenoid-operated switching valve ( 24 ), whose valve member ( 44 ) a valve seat ( 42 ) opens or closes, characterized in that in a plane surface ( 84 ) an anchor plate ( 46 ) an armature assembly of the switching valve ( 24 ) a number of recesses made as straight slits ( 76 ) is executed. Fuel injector ( 10 ) according to claim 1, characterized in that the solenoid-operated switching valve ( 24 ) is executed pressure balanced. Fuel injector ( 10 ) according to claim 2, characterized in that the recesses ( 76 ) in the plane surface ( 84 ) of the anchor plate ( 46 ) in different lengths ( 78 . 80 ) are formed. Fuel injector ( 10 ) according to claim 2, characterized in that the recesses ( 76 ) in the plane surface ( 84 ) of the anchor plate ( 46 ) seen in the circumferential direction in an alternating sequence in a first length ( 78 ) and a second length ( 80 ) are formed. Fuel injector ( 10 ) according to claim 4, characterized in that the first length ( 78 ) of recesses made as straight slits ( 76 ) the second length ( 80 ) exceeds. Fuel injector ( 10 ) according to claim 1, characterized in that in the plane surface ( 84 ) of the anchor plate ( 46 ) between the recesses made as straight slots ( 76 ) preferably designed as bores openings ( 86 ) are executed. Fuel injector ( 10 ) according to claim 1, characterized in that the valve member ( 44 ) of the switching valve ( 24 ) on a pressure pin ( 62 ) whose diameter is the diameter of a valve seat ( 42 ) corresponds. Fuel injector ( 10 ) according to claim 3, characterized in that the recesses ( 76 ) in the plane surface ( 84 ) of the anchor plate ( 46 ) in a division ( 82 ), in particular a 90 ° graduation, are formed. Fuel injector ( 10 ) according to claim 4, characterized in that the recesses ( 76 ) of the second length ( 80 ) in the plane surface ( 84 ) of the anchor plate ( 46 ) in a first division ( 82 ), preferably a 90 ° division are executed.