EP1270930A1 - Magnetic valve for controlling a fuel injection valve of a combustion engine - Google Patents

Abstract

The device has a housing part (39), an electromagnet (29) with magnet coil (32) and core (33). A spring-loaded armature (27) is movable axially between the electromagnet and a valve seat (24). A control valve element (22,25) moves with the armature and interacts with the valve seat for opening and closing a fuel passage (17). The armature is arranged to move radially in the housing part free from mechanical guide arrangements.

Description

State of the art

The invention relates to a solenoid valve for controlling a Injector of an internal combustion engine with the in the preamble of claim 1 specified characteristics.

Such known from DE 196 50 865 Al known solenoid valve is used to control the fuel pressure in the control pressure chamber. an injector, such as an injector one Common rail injection system, related. In such injectors is about the fuel pressure in the control pressure chamber controlled the movement of a valve piston, with the one Injection opening of the injection valve open or closed becomes. The well-known solenoid valve has one in one Housing part disposed electromagnet, one in one Slider guided and acted upon by a closing spring, axially movable armature and one moved with the armature Control valve member, which with a valve seat of the solenoid valve interacts and so the fuel drain from the Control pressure chamber controls. The anchor has an anchor plate and an anchor bolt formed in a bore sliding mechanical guide of the slider is stored.

In the known solenoid valves, the slider must be large Precision machined to ensure optimum functionality to ensure the solenoid valve. The mechanical Anchor guide through the slider causes friction losses, which takes into account in the design of the overall system Need to become. In addition, the installation of the Slider in the housing part of the solenoid valve a mechanical quite elaborate overall construction required.

Advantages of the invention

The advantages of the invention consist essentially in the Saving the previously used slider and the elimination the associated manufacturing and work steps. By eliminating the armature leading slider Friction losses due to the mechanical anchorage avoided when opening or closing the solenoid valve. Advantageous can by eliminating the slider of the structure of the anchor greatly simplified and functionally optimized become. Due to the simplified construction reduces furthermore beneficial the dispersion of the dynamic behavior of the solenoid valve, so that the reliability of the overall system is increased. In addition, there is an essential Advantage from the considerable cost reduction in the Production of the solenoid valve. This is not just the sliding piece saved, but also the anchor can be less expensive designed and, for example, as a simple stamped part getting produced.

Advantageous embodiments and further developments The invention are characterized by those mentioned in the subclaims Features possible.

Characterized in that the anchor formed as a disc-shaped anchor plate which is opposite with their from the electromagnet Side acts directly on the control valve member, a particularly flat construction of the anchor is achieved. Be beneficial to the anchor in the closed position of the solenoid valve transmitted by the closing spring Tipping moments greatly reduced.

Anchor plate and control valve member are advantageous as a separate Made components so that the radially movable Can move anchor plate relative to the control valve member, without the control valve member necessarily from its centric Position is moved relative to the valve seat. A side impact of the control valve member next to the Valve seat and associated with friction losses sliding in the valve seat is thereby largely avoided.

Particularly advantageous is an embodiment in which the armature when a current is applied to the electromagnet in the radial direction by acting on the armature magnetic Reluctance forces in a relative to the central axis the electromagnet centric position is alignable. This can advantageously be achieved in that the anchor and the magnetic core at their mutually facing pole faces concentric about their respective central axis arranged geometric Have structures which structures when energized of the electromagnet interact in such a way that the anchor is aligned in the centric position.

The fact that in the central position of the armature Center axis arranged concentrically to the fuel passage is, can be applied to the anchor acting tilting moments to reduce. When closing the solenoid valve hits the Anchor then from its centric position in the middle of the control valve member, so that in the closed state of the solenoid valve the control valve member centric to the fuel passage abuts the valve seat and tilting moments are reduced.

drawings

Fig. 1 einen Ausschnitt aus dem oberen Teil eines Kraftstoffeinspritzventils mit einem ersten Ausführungsbeispiel des erfindungsgemäßen Magnetventils,

Fig. 2 einen Ausschnitt aus dem oberen Teil eines Kraftstoffeinspritzventils mit einem zweiten Ausführungsbeispiel des erfindungsgemäßen Magnetventils,

Fig. 3 eine vergrößerte Detailansicht des Magnetventils nach einem weiteren Ausführungsbeispiel mit den Anker zentrierenden geometrischen Strukturen,

Fig. 4 eine vergrößerte Detailansicht eines weiteres Ausführungsbeispiels.

An embodiment of the invention is illustrated in the drawings and will be explained in the following description. It shows

1 shows a detail of the upper part of a fuel injection valve with a first embodiment of the solenoid valve according to the invention,

2 shows a detail of the upper part of a fuel injection valve with a second embodiment of the solenoid valve according to the invention,

3 is an enlarged detail view of the solenoid valve according to a further embodiment with the armature centering geometric structures,

Fig. 4 is an enlarged detail view of another embodiment.

Description of the embodiments

1 shows the upper part of a fuel injection valve, which is intended for use in a fuel injection system is, in particular a common rail system for diesel fuel, which is equipped with a high-pressure fuel storage is continuous by a high pressure pump supplied with high-pressure fuel. The fuel injector has a valve housing 4 with a longitudinal bore 5, in which a valve piston 6 is arranged, with his an end, not shown in Fig. 1 on one in a Nozzle body arranged valve needle acts. The valve needle is arranged in a pressure chamber, which has a pressure bore supplied with high-pressure fuel. At a Opening stroke of the valve piston 6 is the valve needle through the constantly on a pressure shoulder of the valve needle attacking fuel high pressure in the pressure chamber against the Clamping force of a spring not shown raised. By a then connected to the pressure chamber injection port takes place the injection of the fuel into the combustion chamber of Internal combustion engine. By lowering the valve piston 6 is the valve needle in the closing direction in the valve seat of the injector pressed and the injection process ended. Of the Valve piston 6 is facing away from the valve needle at its End guided in a cylinder bore 11, which in a valve piece 12 is inserted, which is inserted into the valve housing 4 is. In the cylinder bore 11, the front side closes of the valve piston 6 a control pressure chamber 14, which via a Inlet channel with a high-pressure fuel connection, not shown connected is. The inlet channel is essentially formed in three parts. A radial through the wall of the Ventilstücks 12 leading bore, the inner walls on a Form part of their length an inlet throttle 15 is with a the valve member 12 circumferentially surrounding annular space 16th constantly connected, which annulus in turn in constant communication with the high-pressure fuel connection. About the Inlet throttle 15 is the control pressure chamber 14 in the high-pressure accumulator exposed to high fuel pressure. Coaxial to the valve piston 6 branches from the control pressure chamber 14 a in the valve piece 12 extending bore, one with a Outflow throttle 18 provided fuel drain channel 17 forms which opens into a relief space 19, with a in Fig. 1, not shown fuel low pressure connection connected is. The exit of the fuel drain passage 17 from the Valve piece 12 takes place in the region of a conically countersunk Part 21 of the end face of the valve piece 12. The valve piece 12 is in the embodiment shown here by means of one provided with two mutual clamping shoulders Clamping element 23 together with a housing part 39 of the Solenoid valve via a screw member 7 in the valve housing. 4 clamped. For this purpose, the valve piece 12 has a circumferential Flange 13, which on an annular shoulder 47 of the Valve housing 4 rests. The flange 13 is between clamping element 23 and valve housing 4 clamped. At the other from the valve housing 4 facing away from the shoulder of the clamping element 23 is a dial 48 at. The housing part 39 of the solenoid valve is located with a peripheral edge portion on the dial 48. The screw member 7 is enclosed a clamping shoulder on the solenoid valve housing 39 and is on the valve housing 4 screwed. In this embodiment is with only one screw member 7, the solenoid valve housing 39 fixed to the valve housing 4 and at the same time the valve piece 12 clamped.

In the conical part 21, a valve seat 24 is formed, with a control valve member 22,25 of the injection valve controlling solenoid valve cooperates. The control valve member 22,25 is in two parts with a valve ball 25 and a the valve ball 25 receiving socket part 22 is formed and coupled to an armature 27 which is connected to an electromagnet 29 of the solenoid valve cooperates. Although it is conceivable is to form the armature with the control valve member 22,25 in one piece, is in the preferred embodiment shown here provided, the armature 27 and the control valve member 22,25 form as separate parts. The of the valve ball 25 facing away from the base part 22 is as a flat Support surface for the armature 27 is formed. The armature 27 is in one piece and essentially as a circular disc-shaped Anchor plate formed. The anchor plate has a the electromagnet 29 facing pole surface 37 and one facing away from it flat surface 36, which directly on the base 22nd the control valve member acts. From the center of the pole surface 37 of the armature 27 is a pin 35 from perpendicular, in a Recess 10 of the electromagnet 29 engages, in the also a closing spring 31 is arranged, which is located on the pin 35th supported. The armature 27 and the control valve member coupled to the armature 22,25 are constantly fixed by the housing supporting closing spring 31 acted upon in the closing direction, so that the control valve member 22,25 normally in the closed position abuts the valve seat 24. Upon excitation of the electromagnet the armature 27 is in the axial direction of the valve seat 24th deducted and the drainage channel 17 to the discharge chamber 19 out open.

As can be further seen in Fig. 1, the electromagnet comprises 20, a magnetic coil 32 and a magnetic core 33. The magnetic core 33 has an annular on its pole face 38 Recess 41, in which the magnetic coil 32 is arranged is. Terminals 34 of the magnetic coil are through the magnetic core 33 led to the outside. Through the recess 41, the pole surface 38 of the magnetic core in an inner annular Pole portion 45 and an outer annular Polflächenabschnitt 44 divided, both of the pole face 37 of the anchor plate facing, as in Fig. 3 best can be seen. When a current is applied to the electromagnet forms over the gap between the pole surface portion 44 and the pole face 37 of the armature and the gap between the pole face 37 of the armature and the pole face portion 45 of the magnetic core is a closed magnetic circuit out. Between the pole face of the magnetic core 33 and the pole face 38 of the anchor plate must maintain a minimum distance be a so-called magnetic bonding of the anchor at Magnetic core 33 to prevent. This can, as shown in Fig. 3 is, for example, by a layer 26 of a magnetically non-conductive material on the pole face 37 of the Anchor plate can be achieved. For example, the layer 26 are made of chrome or Teflon. The layer Can be done by soldering, welding, gluing or other suitable Way to be connected to the anchor. It is also possible, between the pole face 38 of the armature 27 and the magnetic core 33 insert one or more spacers. Another way, the minimum distance between anchor plate and magnetic core, is the anchor with structures protruding from pole face 37 (e.g., dimples) to be provided, which at the electromagnet or a supported in the solenoid inserted sleeve. Farther For example, the anchor plate at one in the Electromagnet introduced and from the pole face 38 of the Magnet core 33 projecting sleeve to the plant.

The opening and closing of the injector will be as follows described controlled by the solenoid valve 30. As already shown, the anchor bolt 27 is constantly through the closing spring 31 acted upon in Schließrichtüng, so that the control valve member 25 with non-energized electromagnet in the closed position abuts the valve seat 24 and the control pressure chamber 14 is closed towards the discharge side 19, so that there over the inlet channel very quickly the high Pressure builds up, which is also present in the high-pressure fuel storage. The pressure in the control pressure chamber 14 generates a closing force on the valve piston 6 and the associated standing valve needle, which is larger than the other hand in Opening direction due to the upcoming high pressure acting Forces. If the control pressure chamber 14 by opening the solenoid valve opened to the discharge side 19, builds the pressure in the small volume of the control pressure chamber 14th very quickly, since this over the inlet throttle 15 of the High pressure side is disconnected. As a result, outweighs the force acting on the valve needle in the opening direction the pending on the valve needle fuel high pressure, so that the valve needle moves upward while the at least an injection port is opened for injection. However, closes the solenoid valve 30, the fuel drain passage 17, the pressure in the control pressure chamber 14 through the over rebuilt the inflow channel 15 nachfließenden fuel be, so that the original closing force is pending and the valve needle of the fuel injection valve closes.

As shown in Fig. 1, the armature 27 of the invention Solenoid valve in the housing part 39 of the solenoid valve be moved in the radial direction, without a mechanical guidance to be prevented. In a radial Movement of the armature 27 may be the surface 36 of the anchor plate slide along the base part 22 along. While closing of the solenoid valve, the closing spring 31 presses the armature 27 and the control valve member 22,25 against the valve seat 24, wherein the mechanically unguided anchor plate in a decentralized Meeting on the base part 22 can tilt something. However, it will even with a slight deflection of the anchor plate in radial Direction the control valve member 25 always reliable in the valve seat 24 pressed. Due to the flat design of the Ankers 27 as disc-shaped anchor plate are the tilting moments compared to a T-shaped anchor with from the anchor plate projecting anchor bolt also greatly reduced.

Fig. 2 shows a further embodiment of the invention. The basic structure of the solenoid valve shown in Fig. 2 is Similar to in Fig. 1. The same parts have the same reference numerals. As can be seen, the plate-shaped anchor 27 in contrast to Fig. 1 at its the electromagnet facing side here a central recess 40, in which engages the closing spring 31. The point of attack of Closing spring 31 is particularly close to the ball 25th the control valve member, so that acting on the armature Tipping moments with closed solenoid valve even further reduced become. Furthermore, the valve piece 12 with a clamped separate clamping member 23 in the valve housing 4. The solenoid valve housing 39 is connected to the screw member 7 via an intermediate disc 48 directly on the valve housing 4 attached. In spite of the flat anchor enough space for to have the tendon 23, which is facing the electromagnet End face 12 of the valve piece with a frusto-conical Section 20 provided, which of a Flange 13 is surrounded. The valve seat 24 is centered in the truncated cone-shaped portion 20 introduced. How to recognize is that forms the frusto-conical surface 20 surrounding Room a receptacle for the clamping nut 23, which on the flange 13 of the valve member 12 abuts. The minimum distance between the armature 27 and the solenoid 29 is. by coating the anchor with non-magnetic material reached.

Particularly advantageous is a development of the invention, in which the anchor plate by means of magnetic reluctance forces is centered to decenter the anchor plate and a resulting tilting of the anchor plate at Avoid striking the control valve member. This can be achieved in that the armature 27 and the magnetic core 33 of the electromagnet 29 provided with geometric structures are, which when energizing the electromagnet 29 cooperate such that the armature 27 in a centric Position is aligned, in which its central axis 45 coaxial with the central axis 30 of the electromagnet runs (the central axis 45 and the central axis 30 are on a straight line). This has the advantage that the anchor plate when opening the solenoid valve is always centered and when switching off the electromagnet when closing the solenoid valve from the centric position on the control valve member meets. The geometric structures can both in the case of the magnetic valve shown in FIG. 1 as well as in the FIG be provided. In Fig. 2, the geometric Structures indicated by the reference numerals 41 and 42. A enlarged detail view can be found in FIG. 3.

As can be seen in FIG. 3, the electromagnet 29 a magnetic core 33 and a coil 32. The magnetic core 33 is with a concentric to its central axis 30 extending groove-shaped recess 41 provided, in which the coil 32 is introduced. Through the recess 41, the pole surface 38 of the magnetic core 33 in an outer annular Polflächenabschnitt 44 and an inner Polflächenabschnitt 45 divided. The peculiarity of this embodiment consists in the recess 42, which in the magnetic core 33 facing pole face 37 of the armature 27 concentric with Center axis 45 of the armature is introduced. These too annular recess 42 has in the form of a circumferential groove in about the same outer diameter and inner diameter and thus the same width d as the recess 41 of the magnetic core 33 on. The mutually associated recesses 41 and 42 interact magnetically such that at a Current applied to the electromagnet, the central axis 45 the armature 27 coaxial with the central axis 30 of the electromagnet runs. The magnetic centering effect is explained from magnetic reluctance forces, which at a radial Deflection of the anchor plate occur. Are the recesses 41 and 42 are not arranged congruently one above the other, so become the magnetic field lines at the edges of the two Recesses 41.42 distorted. The resulting reluctance forces pull the anchor plate back up until the Recesses 41, 42 congruent superimposed and the central axis 45 of the armature coaxial with the central axis 30 of the Electromagnet 29 extends. For this purpose, the recess needs 42 not necessarily circumferentially introduced into the armature 27 be. It is also possible to be concentric with the central axis 45 arranged segments or other suitable training to use.

Another embodiment is shown in FIG. at In this embodiment, the pole face 37 of the armature 27 formed without a recess, but has an outer diameter on, which is slightly larger than the inner diameter the outer pole surface portion 44 of the magnetic core. Preferably is the outer diameter of the pole face 37 of the armature designed to be less than a millimeter larger than the inner diameter of the outer pole surface portion 44 of Magnet core 33. When a current is applied to the electromagnet the magnetic field becomes in the overlapping area e of the pole face 37 and the outer pole surface portion 44, because there the magnetic field lines must run closer. The gain is greater, the smaller the overlap area e is. At a radial deflection of the anchor plate have strong reluctance forces in this area, which the anchor plate back to the centric position drive, in which the central axes 30,45 arranged coaxially are (lying on a straight line).

Claims (11)

Solenoid valve for controlling an injection valve of an internal combustion engine, comprising a housing part (39), an electromagnet (29) having a magnet coil (32) and a magnetic core (33), a valve spring (11) axially movable between the electromagnet (29) and a valve seat (24). 31) acted upon anchor (27) and a with the armature (27) moved and with the valve seat (24) cooperating control valve member (22,25) for opening and closing a fuel passage (17), characterized in that the armature (27) free is arranged by mechanical guide means in the radial direction movable in the housing part (39). Solenoid valve according to Claim 1, characterized in that the armature (27) is designed as a disc-shaped armature plate, which armature plate with its side remote from the electromagnet (29) side (36) acts directly on the control valve member (22,25). Solenoid valve according to claim 2, characterized in that the armature plate (27) and the control valve member (22,25) are made as separate parts and the armature plate is displaceable in the radial direction relative to the control valve member. Solenoid valve according to one of Claims 1 to 3, characterized in that, when the electromagnet (29) is energized in the radial direction , the armature (27) acts on the armature (27) in reluctance relative to the center axis (30) of the armature Electromagnet centric position is alignable. Solenoid valve according to Claim 4, characterized in that the armature (27) and the magnetic core (33) have geometrical structures (41, 42, 43) arranged concentrically about their respective central axis (30, 45) on their mutually facing pole faces (37, 38). 44), which structures when current is applied to the electromagnet (29) cooperate in such a way that the armature (27) is aligned in the centric position. Solenoid valve according to one of claims 4 or 5, characterized in that in the centric position, the central axis (45) of the armature (27) is arranged concentrically to the fuel passage (17). Solenoid valve according to Claim 5, characterized in that the geometric structures are formed by recesses (41, 42) in the mutually facing pole faces (37, 38) of the magnetic core (33) and of the armature (27), which coincide in the central position over one another are arranged. (Fig. 3) Solenoid valve according to Claim 7, characterized in that the pole face (38) of the magnetic core (33) facing the armature (27) has a first annular recess (41) in which the magnetic coil (32) is arranged and in which the electromagnet ( 29) facing pole surface (37) of the armature (27) one of said first recess (41) associated concentrically around the central axis (45) of the armature (27) arranged annular or partially annular second recess (42). Solenoid valve according to Claim 5, characterized in that the geometric structure of the magnetic core (33) is defined by a circular pole face portion (44) of the magnetic core surrounding the magnetic coil (32) and the geometric structure of the armature (27) by a circular or annular pole face (37). is formed of the armature whose outer diameter is formed slightly larger than the inner diameter of the annular Polflächenabschnitts (44) of the magnetic core (33). (Fig. 4) Solenoid valve according to claim 9, characterized in that the outer diameter of the pole face (37) of the armature (27) is formed larger by less than one millimeter than the inner diameter of the annular Polflächenabschnitts (44) of the magnetic core (33). Solenoid valve according to one of Claims 1 to 10, characterized in that the valve seat (24) is arranged centrally in a frustoconical surface (20) of the valve passage (12) which projects towards the armature (27) and which is the frusto-conical one Surface (20) surrounding space forms a receptacle for a clamping nut (23), by means of which the valve piece (12) is fixed in the injection valve. (Fig. 2)

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