WO2009053175A1

WO2009053175A1 - Leakage flux reduced armature

Info

Publication number: WO2009053175A1
Application number: PCT/EP2008/062369
Authority: WO
Inventors: Juergen Fridrich; Peter Voehringer; Juergen Ulm
Original assignee: Robert Bosch Gmbh
Priority date: 2007-10-18
Filing date: 2008-09-17
Publication date: 2009-04-30
Also published as: CN101828027B; DE502008002513D1; EP2201238A1; CN101828027A; DE102007049974A1; EP2201238B1; ATE497100T1

Abstract

The invention relates to a solenoid assembly (10), which is utilized particularly for activating a fuel injector. The solenoid assembly (10) comprises a magnetic core (16), in which a magnetic coil (18) is embedded. The magnetic coil (18) activates an armature assembly (20), the armature plate (28) of which is equipped with a number of ridges extending in radial direction (64) for the reduction of leakage flux.

Description

description

title

Leakage flux reduced anchor

State of the art

According to DE 196 50 865 A1 and DE 197 08 104 Al the armature of a solenoid valve is designed as a two-part armature so as to reduce the moving mass of the unit of armature and valve member and thus a bouncing kinetic energy.

In the solenoid valves known from the prior art, a valve element in the de-energized, that is pressed in the inactive state of the solenoid valve, via a preloaded compression spring against a stop. This stop is identical to the valve seat in most cases. At rest, the solenoid valve, i. when solenoid of the solenoid valve is de-energized, the solenoid valve is closed, i. the anchor bolt with the closing element received thereon is pressed by a valve spring into the seat of the closing element. If the magnetic coil of the solenoid valve, however, energized, so there is a force that moves the closing element against the force of the closing spring from the seat. After the end of the energization, the spring biased during the upward movement of the anchor bolt ensures that the closing element is returned to its original position. This is independent of whether a pressure-compensated or a pressure-dependent biased valve is actuated by means of the closing element.

In high-pressure accumulator injection systems, for example common-rail accumulator injection systems, which are used on self-igniting internal combustion engines, electrically controlled fuel injectors are used for the precise injection of the fuel into the combustion chamber of the internal combustion engine. These fuel injectors include various valves, each driven by a magnet. Like all magnetic actuators, a magnet assembly comprises a magnetic coil, a magnetic core and an armature, be it one or more parts. A high-pressure control unit for a solenoid valve according to DE 196 50 865 A1 comprises a magnet group, an armature group and a valve group. The solenoid valve assemblies used to actuate the fuel injectors include in addition to the armature assembly, the one or more parts may be formed, a magnetic core, in which a magnetic coil is embedded with a number of turns. The magnetic core with embedded coil is enclosed by a magnetic sleeve, which is usually made of a paramagnetic material such as X8CrNil8-9. This paramagnetic material represents a significant cost factor in previously used solenoid valve assemblies.

Solenoid valve assemblies, which are controlled by means of an electromagnet, have very short switching times. The switching time at switch-on is composed of a delay in response, at which the energization begins, until the beginning of the armature movement and the stroke time, i. the beginning of the anchor movement until the end of the anchor movement and reaching the anchor stop. The switching time is in addition to the control by the control unit still determined by the magnetic material, in particular its specific electrical conductivity and by the magnetic circuit geometry. In order to achieve short switching times with respect to the suit delay and the stroke time in an electromagnet, a slotting of the armature or Ankerausklinkungen be made as geometric measures. Notches represent a removal of flux-carrying anchor volume for eddy current reduction, as well as slots prevent eddy current circulation in the armature and represent the state of the art to achieve short switching times.

However, the above measures are associated with the significant disadvantage that after the start of Aktorbestromung, i. After the beginning of the energization of the electromagnet, a large portion of the adjusting magnetic flux flows through the notch or the slot, without contributing to the magnetic force. A field diffusion at the anchor starts from both sides equally. Under both sides, the anchor base and the anchor top of the anchor are to be understood. In addition, components in the core bore, such as an anchor bolt of the armature assembly and a circlip including an armature shaft with which the armature plate encloses the armature bolt, form very high magnetic flux densities during the response delay. The causes of these are extreme stray flux formation. The consequence is a considerable extension of the response delay. However, in order to be able to make injections by the fuel injector in a short sequence, a short response delay is extremely advantageous. In addition, high flux densities in the areas mentioned also have an elongating effect on the fall time.

Presentation of the invention The invention has for its object to minimize stray flux formation on anchor assemblies in order to shorten switching times of solenoid valves.

Within the response delay, the magnetic field has only partially penetrated into the armature. The effect of the radial slit provided in the armature, in particular in the armature plate of the armature assembly, as an antiperspirant measure after the beginning of the energization is subject to the effect of the magnetic fluxes passing through the radial slots of the armature. As time progresses, the effects are reversed. In order to additionally achieve a short response delay with a short stroke time, a leakage flux reduced anchor geometry is proposed. The leakage flux reduced anchor geometry proposed according to the invention is characterized in that the armature comprises a continuous armature disk without slots and notches, a web remaining. The underside of a pole face (plan side) of the anchor plate has, for example, grooves arranged at an angle of 60 °. These grooves run, for example, in a 60 ° division along the circumference of the anchor plate on the underside, i. on the pole face of the anchor plate facing away from the anchor plate. The grooves, which are executable instead of a 60 ° graduation in a different graduation on the underside of the anchor plate, however, also have solid material towards the pole face, i. the pole face itself is not interrupted by the grooves, so that forms a closed pole face. Instead of the six grooves running on the anchor plate underside, four or eight grooves - but then in different circumferential pitch - can also be placed on the pole face, i. the plan side of the armature assembly facing away anchor plate underside. In contrast to anchor assemblies, in particular known from the prior art anchor plates, the anchor plate according to the present invention no longer has a radial slot, which was previously implemented as an eddy current reducing measure. The inventively proposed anchor plate has a homogeneous pole surface. When current is applied, which is arranged above the pole face of the inventively proposed armature assembly magnet coil, the magnetic flux penetrates via the planar pole face in the armature assembly, so that a stray flux formation is reduced. An additional field diffusion, which generally sets on the anchor plate underside, is attenuated or ideally completely suppressed. This results in a low flux density in the armature shaft, i. a neck-shaped approach below the anchor plate in the anchor bolt and the circlip at the time of the Ansprechverzugs a.

As time progresses, the magnetic field has already diffused into the armature so far that now the grooves extending in the radial direction on the armature underside begin to act as eddy current-reducing measures. A fall time of the magnetic Valve is significantly reduced due to the lower flux density, which occurs in the armature shaft, the anchor bolt and the circlip.

The solution according to the invention can be used both on self-igniting internal combustion engines as well as on spark-ignited internal combustion engines, such as, for example, direct-injection internal combustion engines.

Brief description of the drawings

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

It shows:

FIG. 1 shows a perspective view of a cut-away magnetic assembly,

Figure 2 is an enlarged perspective view of the adjusting magnetic flux and

Figure 3 shows an embodiment of the stray flux reduced armature geometry.

embodiments

FIG. 1 shows a perspective view of a magnet assembly.

FIG. 1 shows that a magnet assembly 10 comprises a magnet holder 12, which is provided with an annular groove 14 on its outer peripheral surface. In this annular groove, an O-ring is inserted during assembly of the magnet holder 12, with which the magnet holder 12 is sealed during assembly against the injector body of a fuel injector. In the magnet holder 12, a magnetic core 16 is accommodated, which encloses a magnetic coil 18. The magnetic coil 18 within the magnetic core 16 cooperates with an armature assembly 20 comprising an anchor bolt 26 and an anchor plate 28. In the case of a multi-part design of the armature assembly 20, the anchor bolt 26 and the armature plate 28 are connected to one another via a securing disk 22, which is additionally enclosed by a securing sleeve 24.

Figure 2 shows the magnet assembly 10 as shown in Figure 1 with respect to the adjusting magnetic flux. As can be seen from FIG. 2, a magnetic flux 42 is established by the magnetic core 16 of the magnet assembly. This runs around the magnetic coil 18 around, compare reference numeral 42 in Figure 2. However, a large part of the magnetic flux 42 passes through the eddy current reducing radial slot 40, see position 44 in Figure 2. Figure 2 can also be seen that at the bottom 36th the armature plate 28 sets the field diffusion, which provides no contribution to the magnetic force generation in the axial direction. In addition, the components located in a core bore 30 of the magnetic core 16 in the representation according to FIG. 2 form very high magnetic flux densities, including stray flux 26 including the armature shaft 52 during the response delay, see stray flux 46 in FIG. 2 within the core bore 30. The cause of the losses of the magnetic flux through the slot, see position 44 according to FIG. 2 and the stray flux 46 which is established in the core bore 30 of the magnetic core 12, can be seen in stray flux formations which cause a significant extension of the response delay. The term delay is to be understood as meaning the time span which elapses between the beginning of the energization of the magnet coil 18 until the start of the movement of the armature assembly 20.

FIG. 3 shows this in relation to an armature assembly which has a stray-flux-reduced armature geometry.

As can be seen from the illustration according to FIG. 3, the armature assembly 20 shown there comprises an armature, for example formed in one piece, in which the armature pin 26 and the armature plate 28 constitute a single component. From the side view shown in FIG. 3, it can be seen that a pole surface 54 of the armature assembly 20 proposed according to the invention is substantially planar. The pole face 54 of the anchor plate 28 is circular and symmetrical to the axis 60 executed. While the top, i. the pole surface 54 of the armature plate 28 of the armature assembly 20 is flat and has no interruption in the form of a radial slot 40 for eddy current reduction, are located on the opposite side of the pole surface 54 anchor plate 28 groove-shaped recesses 56. The groove-shaped recesses 56 at the bottom of Anchor plate 28 are formed so that between the bottom of a, for example, rectangular groove-shaped groove and the pole face 54 of the anchor plate 28, a web thickness 58 remains of a few tenths of millimeters. Due to this circumstance, the pole face 54 can be designed flat and not interrupted.

From the illustration according to FIG. 3 it can be seen that, for example, six at an angle of 60 °, compare at the underside of the armature plate 28 of the armature assembly 20 Position 62 in Figure 3 in the radial direction 64 extending grooves 56 are located. From Figure 3 it can be seen that in the embodiment shown there of the grooves 56, these have a rectangular groove bottom. The groove bottom could also be rounded or procured in a different geometry according to the tool used. 3 likewise shows a plan view of the pole face 54 of the anchor plate 28 of the anchor assembly 20 proposed according to the invention, that the pole face 54 has no discontinuity in the form of a radial slot 40 extending in the radial direction, but is closed. The groove-shaped recesses 56, shown in dashed lines in the plan view according to FIG. 3, all run on the underside of the anchor plate 28, ie on the side of the anchor plate 28 facing away from the pole face 54.

The armature assembly 20 includes the inventively proposed Streufiussreduzierte armature geometry 50, according to the anchor plate 28 without slots or notches, however, with remaining web thickness 58 between the bottom of the grooves 56 and the Polfiäche 54 of the armature plate 28. When turning on the magnetic core 16 of the magnet assembly 10 penetrates the adjusting magnetic flux 42 enters the armature assembly 20 via the flat-shaped pole face 54. Due to the absence of the radial slot 40, a reduced stray flux occurs, so that the proportion of the magnetic flux 42, which is generated to generate the magnetic force, increases. An additional field diffusion, which usually sets at the anchor base, ie at the bottom of the anchor plate 28 is attenuated or ideally completely suppressed. This results in a lower flux density in the shaft 52 of the armature assembly 20 in the anchor bolt 26 and in the lock washer 22, in particular at the time of the Ansprechverzuges. By the action taken, the Ansprechverzug, ie the time between the beginning of the energization of the solenoid 18 can be shortened to the beginning of the movement of the armature plate 28. As the time progresses, the magnetic field has already diffused into the armature assembly 20 so far that now grooves arranged in the radial run begin to act as a measure reducing eddy current. The task which in the solutions according to the prior art has adopted the radial slot 40, cf. illustration according to FIG. 2, and which resulted in an interruption of the pole surface 54 by a radial slot 40, is now on the lower side, for example shifted in 60 ° division grooves 56 shifted. These begin to act as anti-swirling measures as time progresses, so that the provision of the radial slot 40, ie, the creation of a discontinuity or inhomogeneity in the pole surface 54 and resulting loss 44, can be minimized. The fall time, while the anchor plate 28 is reset and thus the Ankerhubweg is traversed in the opposite direction, can be due to the self-adjusting lower flux density in the armature shaft 52, in the anchor bolt 26 and in the lock washer 22 also reduce. Although, in the illustration according to FIG. 3, the grooves 56 are formed in a 60 ° division 62 on the underside of the anchor plate 28 and extend essentially in the radial direction 64 with respect to the axis 60, the anchor plate 28 can be provided on the underside 36 also a different number of grooves 56 are executed, which then run, for example, in a 90 ° -partition and a 45 ° -partition. These possible embodiments for the realization of a stray flux reduced armature geometry 50 are not shown in the drawing, however.

Claims

claims

1. Solenoid valve assembly (10), in particular for actuating a fuel injector with a magnetic core (16) in which a magnetic coil (18) is inserted, which actuates an armature assembly (20), which an anchor bolt 26 and an armature plate (28, 52 ), characterized in that the armature assembly (20) has a leakage flux reduced anchor geometry (50) with a substantially flat and uninterrupted pole face (54).

2. Solenoid valve assembly (10) according to claim 1, characterized in that the pole face (54) of the magnet assembly (10) is designed opposite and runs in relation to this plan.

3. solenoid valve assembly (10) according to claim 1, characterized in that the anchor plate (28) on its upper side (38), the pole face (54) and on its underside (36) has a number of grooves (56).

4. solenoid valve assembly (10) according to claim 3, characterized in that on the underside (36) of the anchor plate (28) extending grooves (56) in the radial direction (64) extend.

5. Solenoid valve assembly (10) according to claim 3, characterized in that on the underside (36) of the anchor plate (28) extending grooves in a 60 ° -partition (62), in a 45 ° pitch or in a 90 ° Split.

6. solenoid valve assembly (10) according to claim 3, characterized in that between the pole face (54) of the anchor plate (28) and a bottom of the grooves (56) a web thickness (58) remains.

7. Solenoid valve assembly (10) according to one or more of the preceding claims, characterized in that it is used for actuating a fuel injector.

8. solenoid valve assembly (10) according to one or more of the preceding claims che, characterized in that the solenoid valve assembly has a reduced Ansprechverzug between the beginning of the energization of the solenoid (18) until the beginning of the movement of the armature plate (28) and a shortened stroke time from the Start the movement of the anchor plate (28) until reaching an anchor stop on points.

9. solenoid valve assembly (10) according to one or more of the preceding claims, characterized in that due to a reduction of the loss (44) of the magnetic flux (42) and a reduction of leakage flux (46) in the region of the core bore (30) of the magnetic flux (42) is maximized for generating the magnetic force.