WO2009138279A1

WO2009138279A1 - Solenoid valve having an armature slot configuration

Info

Publication number: WO2009138279A1
Application number: PCT/EP2009/053123
Authority: WO
Inventors: Nadja Eisenmenger; Hans-Christoph Magel
Original assignee: Robert Bosch Gmbh
Priority date: 2008-05-16
Filing date: 2009-03-17
Publication date: 2009-11-19
Also published as: DE102008001822A1

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 by way of pressure relief of a control chamber (40). The control chamber (40) is pressurized with fuel under system pressure. Pressure relief of the control chamber (40) is achieved by way of a control valve (24), the valve member (44) of which opens or closes a valve seat (42). An armature assembly of the control valves (24) comprises an armature plate (44), in which a number of recesses (76) is configured, which are configured as straight slots.

Description

description

title

Solenoid valve with anchor slot

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 known from EP-A 1 612 403. With the aid of the control valve, a drain throttle from a control chamber can be closed or released in the fuel return. 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 not completely closing the seat and causing pressure loss and leakage.

In fuel injectors used, for example, on high-pressure accumulator injection systems (common rail), stroke-controlled injectors can be used, which are operated by means of a solenoid valve for controlling the pressure in a control chamber. The preferably needle-shaped injection valve member is controlled, for example, via a servo control room. The pressure in the control chamber is controlled via the solenoid valve, which has a spherical closing element. The solenoid valve is usually not pressure balanced and therefore requires high spring forces, high magnetic switching forces and due to the dimensioning of spring and magnet considerably enlarged space. A disadvantage of solenoid valves, which have a ball as a closing element, the fact that severe restrictions on the sequence of multiple injections exist so that usually very short consecutive injection intervals can not be realized.

For the introduction of fuel into direct-injection internal combustion engines, in particular self-igniting internal combustion engines, increasingly hub-controlled common-rail injection systems are currently used. The advantage of these systems is the fact that the injection pressure can be adapted to the load and speed of the internal combustion engine. Hub-controlled fuel injectors are known, which are actuated via a solenoid valve. The injection valve member is controlled via a servo control chamber. The pressure in the control chamber of the fuel injector in turn is controlled by a solenoid valve. For improved Injektorabstimmung a solenoid valve is necessary, which has the shortest possible switching times, therefore high switching speeds. The use of a pressure compensated trained valve piston allows small spring forces, smaller magnetic forces to be generated by the electromagnet and smaller valve strokes and thus shorter switching times. The shorter valve switching times can improve the injection performance, in particular the multiple injection capability of the fuel injector.

Presentation of the invention

The invention has for its object to provide a valve, in particular a solenoid valve, which realizes very short switching times.

According to the invention, a solenoid valve is proposed, the armature assembly of which has, in particular, an armature plate which is throttled in the edge region and has recesses or openings which allow acceleration of the movement of the armature plate of the armature assembly by the fuel. By the recesses, which may advantageously be formed alternately as straight slots in different lengths along the circumference, or are designed as holes in the anchor plate, the damping forces, i. the flow forces occurring during the movement, which move on the anchor plate and slow it down, can be reduced. As a result, rapid switching movements of the armature plate of the armature assembly are 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 solution proposed by the invention, by attaching in the edge region of the anchor plate, in particular straight slots, in alternating sequence are executed 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. Straight slotting of the armature plate already substantially reduces the damping of its movement in the fuel fluid and further contributes to the reduction of the eddy currents. Furthermore, a straight slit can be manufactured extremely cost-effectively.

As an alternative to the straight long slots, which are preferably formed in an alternating sequence along the circumference of the anchor plate, a combination of short slots and additional openings, for example bores in the partial surfaces of the anchor plate would also be advantageous. Particularly advantageous is an anchor geometry with straight slots, which is used in a fast-switching, in particular pressure-balanced valve, as by this measure the valve speed, i. the switching speed of the armature between the valve seat and upper stop is further increased. However, the anchor geometry proposed according to the invention can also be used for non-pressure compensated switching valves for other purposes.

Brief description of the drawings

With reference to the drawing, the invention will be described below in more detail.

It shows:

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

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

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

embodiments

The illustration according to FIG. 1 shows a longitudinal section through a fuel injector embodied according to the invention. A Kraftstoffϊnjektor 10 is acted upon via a pressure accumulator 12, in which a system pressure prevails, with fuel. The loading of the pressure accumulator 12 (common rail) can be effected by a high-pressure delivery unit, such as, for example, a high-pressure pump of a high-pressure accumulator injection system, which is not shown in the illustration according to FIG. A high-pressure line 14 extending from the pressure accumulator 12 to the fuel injector 10 opens into an injector body 16, in which a storage volume 18 is located. The fuel injector 10 comprises, in addition to the injector body 16, a nozzle body 20 and an actuator housing 22. The actuator housing 22 houses a rapidly switching switching valve 24, which in the embodiment of the fuel injector 10 according to FIG. 1 is designed as a solenoid valve. The switching valve 24 designed as a solenoid valve comprises a magnetic core 26, in which a magnetic coil 28 is embedded. Furthermore, in the magnetic core 26 there is a through-hole in which, embedded in a sleeve 52, a closing spring 54 is inserted, which acts on a valve member 44 of the switching valve 24 in the closing direction.

The storage volume 18 embodied in the injector body 16 serves to damp hydraulic oscillations between the pressure accumulator 12 and the fuel injector 10. Furthermore, the fuel injector 10 comprises a valve piece 30 which delimits a control space 34. The control chamber 34 is connected via an inlet throttle 36 with the storage volume 18 and is acted upon via the inlet throttle 36 with standing under system pressure, stored in the storage volume 18 fuel. A pressure relief of the control chamber 34 via a drain passage 40, in which at least one outlet throttle 38 is formed. The drainage channel 40 opens below a valve seat 42, which is closed in the illustration of Figure 1 by the valve member 44. In the simplest case, the valve seat 42 is designed in the flat surface of the valve piece 30 as a flat seat.

By depressurizing the control chamber 34, the actuation of a preferably needle-shaped injection valve member 32 takes place. At this is a circumferential collar on which a closing spring 66 is supported. The closing spring 66, which puts the preferably needle-shaped injection valve member 32 in its seat 72, on the other hand, is supported on a lower annular surface of the valve member 30 from.

As can also be seen from the illustration according to FIG. 1, the preferably needle-shaped injection valve member 32 is also guided in the nozzle body 20. In the region of the guidance 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 polished sections 68. About this flows under system pressure standing fuel from the storage volume 18 in an annular space 70 and is at the seat 72 at. In the accessory shown in FIG. stand is the preferred needle-shaped injection valve member 32 placed in its seat 72, so that Einspritzöffhungen 74, which are executed at the combustion chamber end of the fuel injector 10, remain closed.

For the sake of completeness, it should be mentioned that in the case of the fuel injector 10 according to the embodiment in FIG. 1, the switching valve 24 actuates an armature assembly. The armature assembly comprises an armature plate 46, on which the valve member 44 is executed. The valve member 44 is guided in an armature guide 48. The armature guide 48 rests on the upper planar surface of the valve piece 30. The Ankerfuhrung 48 and the valve member 30 are hired via a valve clamping nut 50 to a shoulder of the injector body 16 and fixed there. The valve clamping nut 50 has a threaded portion, which is bolted in the illustration of Figure 1 with a corresponding thread on the inside of the actuator housing 22. The valve member 44, at the upper end of the armature plate 46 is formed, is guided on a pressure pin 62, so that the switching valve 24 is pressure balanced. As a result, smaller spring forces acting on the valve seat 42 in the closing direction can be realized; On the other hand, smaller magnetic forces for actuating a pressure-compensated switching valve 24 are possible. This in turn allows smaller valve strokes and faster switching times, which greatly favor the multiple injection capability of the fuel injector 10 proposed according to the invention. On the other hand, however, it is also possible to use a conventional switching valve 24.

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

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

When driving the solenoid coil 28, the armature plate 46 moves together with the valve member 44 in Öff.ungsrichtung upwards. This results in a pressure relief of the control chamber 34, so that the preferably needle-shaped injection valve member 32 moves into this and extends out of its seat 72. From the storage volume 18 flows through the at least one polished section 68 on the lateral surface of the injection valve member 32 and the annular space 70 under system pressure fuel to the open Einspritzöffhungen 74. 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 is terminated. Due to the action of the closing spring 54, the valve member 44 is inserted into the valve seat 42. represents and the pressure relief of the control chamber 34 is prevented via the drain passage 40 with outlet throttle 38. Via the inlet throttle 36, system pressure builds up in the control chamber 34, which acts on the upper end face of the injection valve member 32 and places it in the seat 72, so that the combustion-chamber-side injection openings 74 are closed and the injection is terminated.

According to the anchor plate 46 of the armature assembly of the switching valve 24 is equipped so that it has the lowest possible flow resistance in their movement in the actuator chamber 58 and the highest possible magnetic force can be generated, which allows fast closing movements. The armature plate 46 is provided with recesses or openings, which allow rapid switching movements of the switching valve 24 and minimize eddy currents occurring.

FIG. 2 shows a first embodiment of the armature plate of the switching valve according to the illustration in FIG. 1.

2, a planar surface 84 of the armature plate 46 has recesses 76, which in the embodiment according to FIG. 2 are designed as straight running slots. The formed as a straight slots recesses 76 in the armature plate 84 extend as shown in Figure 2 in different lengths. Reference numeral 78 denotes a first length of the recesses 76 designed as straight slots, while a second length thereof is designated by reference numeral 80. The first length 78 exceeds the second length 80 by about twice. As can also be seen from FIG. 2, a 90 ° graduation 82 is formed between the recesses 76 of first length 78 in the form of a slot, designed as straight slots. This applies analogously to the division of the recesses 76, designed as straight slots, of second length 80, which are likewise formed in the plane surface 84 of the armature plate 46 in a 90 ° pitch.

Due to the geometry of the plane surface 84 of the anchor plate 46, the eddy current losses and the damping forces can be considerably reduced. In an advantageous manner, slots which have just been formed-as shown in FIG. 2 -are executed in the plane surface 84 of the anchor plate 46. These can be produced inexpensively and allow a strong reduction of the damping force with low loss of magnetic force. A particularly good tuning is achieved by alternating long and short slots shown in alternating sequence, as indicated by the first length 78 and the second length 80 of the slot-shaped configured recesses 76 in Figure 2. The embodiment according to Figure 2, the relatively large area in the outer region of the anchor plate 46 is particularly Well dethrottled, without a further loss of magnetic force by a reduction of the surface at the inner pole occurs.

The illustration according to FIG. 3 shows a further embodiment of the design of the anchor plate. The illustration according to FIG. 3 shows a plane surface 84, which has a combination of recesses 76 of first length 80 designed as straight slots with openings 86 provided therebetween as bores. Also in the embodiment according to Figure 3 can be a very high Entdrosselung the large

Surface can be achieved in the outer region of the armature plate 46 of the armature assembly, 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 of Figure 2, in a fast-switching pressure-balanced switching valve 24 - as shown in Figure 1 - since thereby the valve speed between the upper stop and valve seat 42 can be increased. The inventively proposed switching valve 24 with the fast switching movements enabling armature plate 46, of course, can be used even when not pressure balanced designed switching valves 24.

In order to keep the manufacturing costs low, the embodiment shown in the representation according to FIG. 2 is preferable to a plane surface 84 of the anchor plate 46 which has only slots-but of different lengths 78, 80.

Also in the illustration according to FIG. 3, there is a 90 ° division between the individual recesses 76 of first length 78, which are designed as straight slots, in the plane surface 84 of the anchor plate 46. Of course, it is possible to provide in the plane surface 84, the individual designed as a straight slots recesses 76 of different lengths 78, 80 in a deviating from a 90 ° division 82 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 are placed on the switching speed of the switching valve 24 from.

The degree of Entschrosselung, which is achieved by the present invention proposed solution, whether by recesses formed as straight slots 76 of different lengths 78, 80, or through openings 86 in the flat surface 84, determines the switching speed of the switching valve 24, since the anchor plate 46 in the actuator chamber 58 on the low pressure side of the Kraftstoffϊnjektors 10 is moved. In addition to the execution of the recesses 76 in the flat surface 84 of the anchor plate 46 as rectangular, straight slots, can also be deviated from this geometry, with an optimum between the Entdrosselung in the outer region and minimizing the magnetic force profile in the remaining inner region of the flat surface 84 of the armature plate 46 opposite the inner pole of the magnetic core, is desirable.

The greatest possible reduction of the plane surface 84 of the anchor plate 46 in the outer region allows lower flow resistance during the movement of the anchor plate 46 in the low-pressure side actuator chamber 58.

Claims

claims

1. 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), which is acted upon by a system pressure and the pressure relief of the control chamber (40) via a magnetbetätigter Switching valve (24) takes place, the valve member (44) opens or closes a valve seat (42), characterized in that in a plane surface (84) of an anchor plate (46) of an armature assembly of the switching valve (24) a number executed as straight slots Ausneh- mungen (76) is executed.

2. Fuel injector (10) according to claim 1, characterized in that the solenoid-operated switching valve (24) is designed to be pressure balanced.

3. fuel injector (10) according to claim 2, characterized in that the designed as a straight slots recesses (76) in the flat surface (84) of the anchor plate (46) in different lengths (78, 80) are formed.

4. fuel injector (10) according to claim 2, characterized in that the designed as straight slots 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.

5. Fuel injector (10) according to claim 4, characterized in that the first length (78) of the recesses (76) designed as straight slots exceeds the second length (80).

6. Fuel injector (10) according to claim 1, characterized in that in the plane surface (84) of the anchor plate (46) between the openings designed as straight recesses (76) are preferably designed as bores openings (86) are executed.

7. fuel injector (10) according to claim 1, characterized in that the valve member (44) of the switching valve (24) is guided on a pressure pin (62) whose diameter corresponds to the diameter of a valve seat (42).

8. fuel injector (10) according to claim 3, characterized in that the designed as a straight slots recesses (76) in the flat surface (84) of the anchor plate (46) in a pitch (82), in particular a 90 ° pitch formed ,

9. fuel injector (10) according to claim 4, characterized in that the designed as a straight slots recesses (76) of the second length (80) in the flat surface (84) of the anchor plate (46) in a first pitch (82), preferably one 90 ° division are performed.