DE102006021735A1 - Solenoid valve with flooded anchor space - Google Patents

Abstract

The invention relates to a fuel injector (10) with a solenoid valve (12) which comprises a magnetic yoke (16) and a magnetic coil (18) as well as an armature (32, 34). The armature (32, 34) is urged in the closing direction by a closing spring (26). Between an end face (58) of the magnet yoke (16) and an end face (54) of the armature (32, 34) runs a cavity (50) which absorbs the taxable amount. A recess (56, 66) which enlarges the volume of the cavity (50) is formed on at least one of the end faces (54, 58).

Description

State of technology

DE 199 50 861 A1 refers to a solenoid valve. It is disclosed a solenoid valve, the armature is formed in several parts and has an armature plate and an anchor bolt. The anchor bolt is guided in a slider. In order to avoid ringing of the armature disk after closing the solenoid valve, a damping device is provided on the armature. With such a damping device exactly the required short switching times of the solenoid valve can be maintained. The solenoid valve is intended for use in injection systems with high-pressure accumulator injection systems (common rail) on self-igniting internal combustion engines.

Out DE 103 05 985 A1 is a bounce-free magnetic actuator for injectors known. A magnetic actuator for actuating a fuel injector comprises a magnetic core, in which a magnetic coil is accommodated. A closing spring acts on the armature in the closing direction. Between an armature facing side of a stop sleeve and the armature an exit slit for an actuating fluid is formed. The outlet gap opens into a hydraulic damping chamber, which is delimited by an end face of the magnet armature and by a damping surface made of non-magnetic material.

at the known from the prior art solenoid valves are for Realization of extremely short switching times the residual air gaps of the magnetic circuits designed very small. The residual air gap is the distance between a magnetic yoke and the armature after its operation is called. The fuel that due to the pressure relief of a control room, for example in the resulting cavity between the magnetic yoke (magnetic core) and The anchor gets through the very fast switching process repressed and tends, due to the high discharge rate, for vapor bubble formation, d. H. for cavitation. During the subsequent refilling of the Cavity with fuel break the vapor bubbles together, resulting in a high mechanical load, in extreme cases even cavitation erosion, leads the components, the high pressures are set off by the sudden implosion of the vapor bubbles to adjust. The damage resulting from the cavitation erosion lead the components that the set stroke of an armature assembly within a solenoid valve impaired so that it adds to inaccurate, undefined strokes of the armature assembly Energization of the solenoid of the solenoid valve comes, which in turn to scatter the amount of fuel injected into the combustion chamber leads.

epiphany the invention

Of the present invention is based on the object, a constructive Provide a design of a solenoid valve, which damage the Prevents components of a solenoid valve from cavitation erosion.

Of the proposed according to the invention solution Following, the contour of either a magnetic yoke of the solenoid valve or the contour of a magnetic yoke opposite end of the armature assembly designed to hold a large volume at cavitation-erosion critical sites and a small volume cavitation-erosion-critical sites in the cavity, d. H. in the Air gap between the armature and the magnetic yoke of the solenoid valve established. The design of the contours either on the anchor opposite Front side of the magnetic yoke or at the magnetic yoke opposite Front side of the armature assembly, affects the magnetic properties of the solenoid valve, in particular the magnetic flux, not.

By the proposed contouring of either the magnetic yoke or the Face of the anchor assembly become within the enlarged volume resulting cavitation bubbles brought to implosion, causing the surface stress both the end face of the magnetic yoke and in particular the Front side of the armature assembly is significantly reduced.

In an advantageous embodiment of the contouring either the End face of the magnetic yoke or the face of the anchor assemblies, can the residual air gap, which is in the energized state of the magnetic yoke between the front side and the front side of the armature assembly adjusts, on the edge of the face of the anchor assembly or on the edge of Magnet yoke be designed smaller than in the middle. Thereby turns a smaller gap width within the edge area between the end face of the magnetic yoke and the front side of the Anchor assembly, whereby the flow rate of the fuel off the cavity between magnetic yoke and armature at the end of Ankerhubbewegung throttled, d. H. slows down and the cavitation tendency considerably is lowered.

One further proposed by the invention solution achievable advantage is to be seen in that a damped movement limitation the armature assembly with a lower mechanical stress the components of the solenoid valve takes place, which the life of the proposed solenoid valve significantly increased.

drawing

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

It shows:

1 a solenoid valve assembly of a fuel injector according to the prior art,

detail Z is an enlarged view the cavity between an end face of the magnetic yoke and the Front side of the magnet yoke opposite armature,

2 a first embodiment variant of the front side of the armature with flat end face of the magnetic yoke in the de-energized state of the solenoid valve,

2.1 in the 2 illustrated embodiment of a solenoid valve assembly in the energized state,

3 a further embodiment of a contouring of the front side of an anchor,

4 a first embodiment of the contouring of the end face of the magnetic yoke with plan trained anchor end face and

5 a second embodiment of the contouring of the end face of the magnetic yoke at plan executed end face of the armature.

variants

From the illustration according to 1 is a section through a solenoid valve assembly of a fuel injector according to the prior art.

In a fuel injector 10 is a solenoid valve 12 accommodated. The fuel injector 10 includes an injector body 14 , in which other components of the fuel injector 10 , such as a pressure-relieved control chamber, with which a preferably needle-shaped injection valve member is actuated, are arranged. These other components of the fuel injector 10 are in the illustration according to 1 not shown in detail.

The solenoid valve 12 includes a magnetic coil 18 , which of a magnetic yoke 16 is enclosed. The magnetic yoke 16 is also referred to as a magnetic core. The magnetic coil 18 will have at least one coil contact 20 electrically contacted. The magnetic yoke 16 is over an intermediate plate 22 and an attachment disposed above 24 in the fuel injector 10 added. The magnetic yoke 16 rests on a disc-shaped insert 42 of the fuel injector 10 from.

In the magnetic yoke 16 runs through opening 28 into which a sleeve 30 is admitted. The sleeve 30 encloses a closing spring 26 that are attached to the attachment 24 supported. The closing spring 26 encloses an anchor pin 36 which is located on the upper face of an anchor bolt 34 extends. At the anchor bolt 34 is also an anchor plate 32 added.

The one anchor disk 32 and an anchor bolt 34 comprehensive anchor assembly is in a guide hole 40 the disc-shaped insert 42 guided. Between the outer circumference of the armature disc 32 and the inner diameter of the guide hole 40 in the disc-shaped insert 42 results in a guide gap 38 , over which one from the in 1 not shown control chamber of the fuel injector 10 outflowing control amount flows in the direction of a low-pressure side return.

About the in 1 shown arrangement is when energizing the optional of a sheath 44 enclosed magnetic coil 18 , the anchor plate 32 dressed. This will be the one with the anchor plate 32 connected anchor bolts 34 mounted in the vertical direction and releases an outlet throttle of an injection valve member acting on the control chamber, pending in the system pressure. The system pressure applied to the control chamber is generated by a high pressure source such as a high pressure reservoir (common rail) of a high pressure fuel injection system. When pressure relief of the control chamber by opening a closing element exits a control amount from the control room and flows to a low-pressure side flow and passes while a 2 cavity shown in detail 50 between the anchor plate 32 and the yoke 16 of the solenoid valve 12 ,

detail Z shows the between the magnetic yoke and the armature disc of Anchor assembly adjusting cavity in an enlarged view.

From the detail z it is apparent that the cavity 50 between a front side 54 the anchor plate 32 and a front side 58 of the magnetic yoke 16 (Magnetic core) is located and from the plan running front side 58 of the magnetic yoke 16 and the plan also executed plan 54 the anchor plate 32 is limited. With reference number 68 is an end face of the closing spring 26 enclosing sleeve 30 denoted in a through hole 28 of the magnetic yoke 16 or the magnetic core is embedded. From the detail Z shows that the gap between the planned running front side 58 of the magnetic yoke 16 and the plan formed end face 54 the anchor plate 32 seen in the radial direction has a substantially constant course, which is the occurrence of cavitation bubbles when switching the solenoid valve 12 due to the high flow rate from the cavity 50 favored.

2 shows a first embodiment of the contour of an end face of an anchor according to the inventive solution.

From the illustration according to 2 it turns out that the front side 28 of the magnetic yoke 16 plan is still running. The valve spring 26 encloses the anchor pin 36 , which is at the upper end of the anchor bolt 34 is formed and acts on the upper end face of the anchor bolt 34 , At the anchor bolt 34 is located positively, positively or materially absorbed the anchor plate 32 , The in the representation according to detail Z plan formed end face 54 the anchor plate 32 is, following the solution proposed by the invention, with a conical recess 56 Mistake. The conical recess 56 extends from the seat of the anchor plate 32 on the circumference of the anchor bolt 34 radially outwardly and is constructed such that the conical recess 56 forms a maximum recess (see illustration according to 2.1 ), from its radial position, the conical recess 56 radially to the edge region of the armature disk 32 expires. Through the conical recess 56 at the front 54 the anchor plate 32 arises at the cavitation critical point a large volume and further at the edge region of the front page 54 the anchor plate 32 a smaller volume. The edge area of the anchor disc 32 represents a cavitation-uncritical area within the cavity 50 dar. The in the cavity 50 contained fuel due to the high discharge rates from the cavity 50 to form cavitation bubbles in this tends to form a damping volume between the front side 68 the sleeve 30 and the front of the anchor bolt 34 on which the anchor plate 32 is attached.

2.1 shows the in 2 illustrated, inventive embodiment of the solenoid valve assembly in the energized state of the solenoid valve.

In energized state of the magnetic yoke 16 enclosed magnetic coil 18 becomes the anchor plate 32 attracted and moves into the cavity 50 as shown in 2 into it. That in the cavity 50 existing control volume is displaced and flows in the radial direction sideways out of the cavity 50 from. The flow rate of the in the cavity 50 contained control volume is through an air gap 60 with throttle effect, located at the outer edge of the armature disc 32 opposite the plan formed end face 58 of the magnetic yoke 16 adjusts, throttled, so that the inclination of the cavity 50 flowing fuel volume is significantly reduced for cavitation. Furthermore, by the ring on the front side 54 the anchor plate 32 extending, conical recess 56 in the area of an air gap 62 a larger volume formed, which at the cavitation critical point of the end face 54 the anchor plate 32 lies. reference numeral 52 denotes an averaged residual air gap which is an average between the air gap 62 at its longest extent and an air gap in the edge area between the armature disk 32 and the plan formed end face 58 of the magnetic yoke 16 represents.

In the 2.1 shown position with energized solenoid 18 of the solenoid valve 12 lies the front side of the anchor bolt 34 to which the anchor pin 36 is formed, at the stop 68 who is the closing spring 26 enclosing sleeve 30 at.

In the through the inner air gap 62 defined volume cavitation bubbles that have formed there can be imploded, causing damage to the front 54 can be significantly reduced by cavitation erosion.

The representation according to 3 is a further embodiment of the inventively proposed solenoid valve assembly refer.

The representation according to 3 is removable, that on the front side 54 the anchor plate 32 an annular, trough-shaped recess 66 is trained. Seen in the radial direction, the trough-shaped recess 66 at the frontal area 54 the anchor plate 32 through an edge bridge 64 limited. The edge bridge 64 takes over the throttle effect similar to the conical tapered recess 56 according to the in 2 illustrated embodiment of the solenoid valve 12 , In the tightened state of the anchor plate 32 with energized solenoid 18 , that flows out of the cavity 50 displaced fuel volume across a gap extending between the plane-shaped end face 58 of the magnetic yoke 16 and the top of the edge land 64 adjusts radially out of the cavity 50 from. Through the over the edge bar 64 at the front 54 the anchor plate 32 Throttling effect is the flow rate of the control volume of volume from the cavity 50 limited, which significantly reduces the Kavitationsneigung the tax volume contained therein. As in the trough-shaped recess 66 at the front 54 the anchor plate 32 a volume of fuel is contained, is an attenuation of the lifting movement of the armature assembly, the Ankerschei be 32 and the anchor bolt 34 comprehensive, accessible. Analogous to the embodiments according to the 2 and 2 .1 is located in the passage opening 28 in the magnetic yoke 16 the sleeve 60 which the closing spring 26 encloses. The closing spring 26 encloses with its individual turns on the front side of the anchor bolt 34 trained anchor pin 36 , In the illustration according to 3 , is the cavity 50 between the front side 54 the anchor plate 32 and the front side 58 of the magnetic yoke 16 limited, the plan is executed.

4 shows a further embodiment of the present invention proposed solenoid valve assembly.

In modification of the 2 and 3 illustrated embodiment is shown in the illustration 4 the front side 58 of the magnetic yoke 16 contoured, whereas the face 54 the anchor plate 32 plan is formed. In the illustration according to 4 are the according to the embodiment in 3 at the front 54 trained, trough-shaped recesses 66 , not on the front 54 the anchor plate 32 but at the front 58 of the magnetic yoke 16 , The trough-shaped recess 66 at the front 58 of the magnetic yoke 16 is formed, runs at the front side 58 in ring form. The trough-shaped recess 66 at the front 58 , is through a magnetic yoke 16 trained edge bridge 64 limiting, which acts in terms of reducing the discharge rate of control volume of volume from the cavity 50 analogous to the embodiment according to 3 , sets. The face 54 the anchor plate 32 ends flush with the face of the anchor bolt 34 on which the anchor pin 36 located in the interior of the closing spring 26 protrudes. The magnets yoke 16 trained, ring-shaped, trough-shaped recess 66 can a damping contribution to the stroke movement of the armature disk 32 towards the magnetic yoke 16 in the event that the magnetic yoke 16 enclosed magnetic coil 18 about the in 1 shown at least one coil contact 20 is energized.

The representation according to 5 Finally, a variant of the inventively proposed solenoid valve assembly is shown, in which the end face of the magnetic yoke 16 is provided with a conical recess.

The representation according to 5 represents a reversal of the embodiment according to the representations in the 2 and 2.1 According to the in 5 illustrated embodiment of the present invention proposed solenoid valve assembly is the conical recess 56 at the front 58 of the magnetic yoke 16 or the magnetic core. This still shows the sleeve 30 on which the closing spring 26 surrounds. The closing spring 26 supports, the anchor pin 36 of the anchor bolt 34 enclosing, on the front side of the anchor bolt 34 from. Due to the conical geometry of the recess 56 at the front 58 of the magnetic yoke 16 On the one hand, a high volume is made available at the most cavitation critical point by tightening the armature disk 32 and the resulting outflow of control volume in this cavitation bubbles formed can be made to implosion, without causing cavitation erosion both on the flat end face 54 the anchor plate 32 , as well as on the front side 58 of the magnetic core 16 comes. In addition, the forms on the front surface 58 trained conical recess 56 a damping volume through which the stop movement of the end face of the anchor bolt 34 to the stop 68 the sleeve 30 can be dampened. Ideally, this can be achieved through the cavity 50 recorded control volume volume material contact between the front side of the anchor bolt 34 and the front side 68 the sleeve 30 which the closing spring 26 encloses, completely avoid. For completeness, it should be mentioned that in connection with the 2 to 5 illustrated cavity 50 with energization of the solenoid 18 coming from the yoke 16 is enclosed by the tightening movement of the anchor plate 32 continuously decreases, thereby increasing the high flow rates of control volume from the continuously decreasing cavity 50 comes. By inventively proposed solution, can be approximately in the middle of the radius of the armature disk 32 represent large volumes and in the edge region in the radial direction relative to the armature disk 32 , adjust low volumes. The cavity 50 between the front side 58 of the magnetic yoke 16 and the front side 54 the anchor plate 32 increases when the energization of the solenoid coil is canceled 18 of the solenoid valve 12 because of the anchor bolt 34 through the closing spring 36 is pressed into its closed Stel development in which a closure member not shown in detail, a pressure relief of a control chamber for actuating an injection valve member terminated.

Claims (8)

Fuel injector ( 10 ) with a solenoid valve ( 12 ), which is a magnetic yoke ( 16 ) and a magnetic coil ( 18 ) as well as an anchor ( 32 . 34 ), wherein the armature ( 32 . 34 ) by a closing spring ( 26 ) is acted upon in the closing direction, and between a front side ( 58 ) of the magnetic yoke ( 16 ) and a front side ( 54 ) of the anchor ( 32 . 34 ) a control volume receiving cavity ( 50 ), characterized in that at least one the front sides ( 54 . 58 ) one the volume of the cavity ( 50 ) enlarging recess ( 56 . 66 ) is trained. Fuel injector according to claim 1, characterized in that a maximum increase in volume ( 62 ) of the cavity ( 50 ) is located at the cavitation critical point, which - in the radial direction of the end faces ( 54 . 58 ) - between an inner radius of an armature disk ( 32 ) and half of its outer radius (r _r - r _i / 2). Fuel injector according to claim 1, characterized in that the recess ( 56 . 66 ) is tapered or trough-shaped. Fuel injector according to claim 3, characterized in that the conical recess ( 56 ) an air gap ( 60 ) with throttle effect with an opposite end face ( 54 . 58 ). Fuel injector according to claim 3, characterized in that the conical recess ( 56 ) either on the front side ( 58 ) of the magnetic yoke ( 16 ) or on the front side ( 54 ) of the anchor ( 32 . 34 ) runs. Fuel injector according to claim 3, characterized in that the trough-shaped recess ( 66 ) either on the front side ( 58 ) of the magnetic yoke ( 16 ) or on the front side ( 54 ) of the anchor ( 32 . 34 ) runs. Fuel injector according to claim 3, characterized in that the trough-shaped recess ( 66 ) by an edge web ( 64 ) is limited. Fuel injector according to claim 3, characterized in that the conical recess ( 56 ), seen in the radial direction, is continuous.