DE102006020724A1 - Solenoid valve with self-centering anchor bolt - Google Patents

Abstract

The invention relates to a fuel injector (10) with a solenoid valve (14) for actuating a closing element (52). The pressure in a control chamber (60) acting on an injection valve member (62) is relieved via the closing element (52). The solenoid valve (14) comprises an armature bolt (44) on which an armature plate (40) is movably received. The anchor bolt (44) is guided by an anchor guide (46). The armature bolt (44) is acted upon by a valve spring (32) of the solenoid valve (14). The valve spring (32) is accommodated between the armature bolt (44) and the armature guide (46).

Description

State of technology

DE 196 50 865 A1 describes a solenoid valve for controlling the fuel pressure in a control chamber of an injection valve, such as a common rail high pressure injection system. About the fuel pressure in the control chamber, a stroke movement of a valve piston is controlled, with which an injection port of the injection valve is opened or closed. The solenoid valve comprises an electromagnet, a movable armature and a valve member moved with the armature and acted upon by a valve closing spring in the closing direction, which cooperates with the valve seat of the solenoid valve and thus controls the fuel drain from the control chamber.

It is a common-rail injector with a two-piece anchor known which is attracted by a solenoid valve. The anchor exercises in the currentless case of the solenoid valve, a closing force on a valve ball. Will the solenoid of the solenoid valve energized, the armature moves up to the armature stroke, the closing force the valve ball becomes 0 and a discharge valve opens. An anchor guide, the firmly in the injector body bolted to the fuel injector, takes on the anchor bolt. On the anchor bolt, the anchor plate is guided, which in turn from the electromagnet is attracted. The anchor bolt can due to the leadership game the anchor guide tilt. The anchor plate in turn can tilt on the anchor bolt, so that the total tilt of the assembly anchor bolt / anchor plate in reference to, for example, the injector main axis as the sum of the guide games determine. The anchor plate has a defined Überhubanschlag on the anchor guide, the the kinetic energy of the movement of the armature after shutdown of the electromagnet is removed from the system. When the valve ball in their seat is hit, the anchor bolt is stopped in his movement. The anchor plate can still move relative to the valve pin to an overstroke (ballistic operating phase) before striking the overstroke stop. Consequently only needs a part of the kinetic energy from the movement of the anchor bolt be reduced in Ven tilsitz. The part of the kinetic energy out the anchor plate is degraded in the injector body.

at current series products, the problem arises that the one closing force practicing on the anchor bolt Valve spring Transverse force components in the assembly of anchor plate and Anchor bolt initiates. Due to the guiding play between the anchor guide and the anchor bolt leads this leads to a tilting of the anchor bolt in the anchor guide. at strong lateral force introduction, this tilting can also in the upper Position of the anchor bolt to be present at energized electromagnet, because an anchor bolt stop can rest on one side. This will be one Part of the set armature stroke, i. the movement of the anchor bolt in operation, not complete exploited. this leads to to a lower injection amount of fuel into the combustion chamber an internal combustion engine. Added to this is the friction of the anchor bolt in the anchor guide, which also affects the movement of the anchor bolt. This friction takes with a larger tilt angle too, because the lever arm of the triggering force is also increasing. The point of application of the valve spring has a relative huge Distance to the upper end of the anchor guide. This creates on upper and at the lower end of the anchor guide very high punctual acting personnel on the anchor bolt, which reinforce its deflection and thus the friction and thus slowing down the movement of the anchor bolt relative to the armature guide can. The Speed at which the anchor bolt moves, i. the speed of opening and closing of the closing element has a very big one Influence on the introduced in the combustion chamber of the combustion engine Injection quantity.

Around To cope with this problem, the leadership game has been limited in attempts with which Aim to reduce the tilt angle. A limitation of the leadership game within the Armature assembly in turn leads In addition, the anchor bolt does not have a consistent position during operation maintains, but to take another position from injection to injection can. This is changing friction between anchor bolt and anchor guide and thus it remains with a scatter of injection quantities. Furthermore has been proven by the previously described Total tilting of the anchor plate and the anchor bolt by the tilt angle relative to the injector main axis a collision between anchor plate and magnetic core with small, remaining residual air gap between Anchor plate and magnetic core can occur and on the other hand with a uniform residual air gap also a non-uniform on the circumference distributed magnetic force occurs. This strengthens the random friction forces and thus has an impact on those realized with the fuel injector Injection amounts of fuel into the combustion chamber of the internal combustion engine.

In full ballistic injector concepts, the map of the fuel injector is greatly affected by the friction effects within the fuel injector. Therefore, it is desirable to ensure as constant as possible friction conditions over the life of the injector. In the previous constructions of the armature assembly a tilting effect is generated by a valve spring acting from above on the anchor bolt, which is on the above-mentioned transverse force shares based. The lateral force components produce lateral forces that can lead to smoothing effects or other changes in the relatively moving surfaces within the armature assembly over the running time of the fuel injector. As a result, the friction conditions are changed, which in turn changes the characteristics of a fully ballistic operated fuel injector.

epiphany the invention

Of the proposed according to the invention solution Following is the force application point of the valve spring of the solenoid valve so that shifts a lower tilting effect on the anchor bolt the armature assembly results. This leads to a self-centering of the anchor bolt and thus to constant friction conditions in the anchor assembly. On the other hand, the change of the force application point the valve spring better alignment of the valve spring within the armature assembly, since the installation position of the valve spring is no longer from the positioning of the magnetic core in the injector body of the Fuel injector dependent is, but only by the mating anchor bolts and anchor guide the anchor assembly.

Of further results from the proposed proposed laying the force application point of the valve spring on the fuel injector the possibility the waiver of a dial, with the previously known solutions the valve spring force was adjusted. In the previously used Injectors, the use of a shim is necessary because the bias of the valve spring of many manufacturing parameters depends. Of the Compensation of the tolerances of the manufacturing parameters takes place in the Assembly of the fuel injector by using just this Shim. In the proposed solution according to the invention the valve spring from the through hole of the magnetic core of the solenoid valve shifted, which on the one hand a reduction in the diameter of the Achieves through-hole, since these no longer according to the outer diameter of the valve spring must be dimensioned; On the other hand, the volume of the magnetic core elevated be, which in turn results in an increase in the recoverable magnetic force can achieve. Can about the Magnetic core of the solenoid valve for actuating a fuel injector generates larger forces so can a higher one System pressure in the case of high-pressure accumulator injection systems (common rail) be controlled in the range between 1800 and 2000 bar.

at the inventively proposed solution of selbstzyndrierenden anchor bolt is the armature guide so in the injector body of the fuel injector strained that their leadership section to the closing element extends, which opens an outlet throttle of a pressure-relieved control chamber or closes. The guide section the anchor guide on the one hand forms a stop for the valve spring and on the other hand a stop for an over-travel spring, which the anchor plate movable relative to the anchor bolt against a sickle disc biases. The valve spring, which preferably at the annular surface of the armature guide supports, supports on the other hand, on an annular surface on the lower side of the Anchor bolt on which a closing element guide for guiding a e.g. spherical form closing element is included.

The armature guide is firmly fixed with its annular surface in the injector body of the fuel injector. The valve spring surrounding the guide section of the armature guide is independent of the installation position of the magnetic core relative to the armature guide and annular surface of the anchor bolt and is therefore independent of manufacturing tolerances, apart from the manufacturing tolerance between the outer peripheral surface of the anchor bolt and diameter of the passage point of the armature guide. Compared to the previous solution from the prior art (see. 1 ) results in relation to the injector main axis by the force application point of the valve spring on the underside of the annular surface of the armature guide a much lower introduction of shear forces on the anchor bolt, ideally be introduced by the inventively proposed solution transverse force components 0.

drawing

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

It shows:

1 a section through a fuel injector with a solenoid valve according to the prior art

2 the invention proposed displacement of the valve spring for self-centering of the anchor bolt.

variants

1 shows a fuel injector with a solenoid valve and an armature assembly according to the prior art.

A fuel injector 10 as shown in 1 includes an injector body 12 in which a solenoid valve 14 is included. Above the solenoid valve 14 there is a lid 16 , in a low-pressure side return 18 is executed. The lid 16 is by means of a seal 20 against a magnet sleeve 22 sealed. The magnet sleeve 22 fixes both the lid 16 as well as a magnetic core 26 of the solenoid valve 14 , The magnet sleeve 22 is by means of a clamping nut 24 with the injector body 12 of the fuel injector 10 fixed with application of a defined tightening torque.

In a through hole 28 of the magnetic core 26 there is a valve spring 32 , The valve spring 32 supported on the one hand on the lid 16 and on the other hand to an anchor bolt 44 an anchor assembly from. At the anchor bolt 44 is an anchor plate 40 relatively movable to the anchor bolt 44 taken on the one hand by a lock washer 36 coming from a locking sleeve 34 is enclosed at the anchor bolt 44 is secured and on the other hand by a Überhubfeder 42 is charged. The over-travel spring 42 encloses a guide portion of the anchor plate 44 as well as an anchor bolt guide 46 , The anchor bolt guide 46 is in turn via a clamping nut in the injector body 12 of the fuel injector 10 fixed. At the anchor guide 46 are holes 48 executed to a flow out of a control room 60 of the injector body 12 controlled flow rate in the direction of the low pressure side of the return 18 in the lid 16 to enable.

The anchor bolt 44 includes a closing element guide 50 below the anchor guide 46 lies. The closing element guide 50 enclosing an in 1 spherical trained closing element 52 partially. By means of the anchor bolt 44 recorded closing element 52 becomes an outlet throttle 58 a control room 60 open or closed. The control room 60 in the fuel injector 10 is through a valve piece 56 limited, in which the outlet throttle 58 for pressure relief of the control room 60 is trained. The valve piece 56 forms a seat 54 for the closing element 52 , The control room 60 is on the one hand by the valve piece 56 limited and on the other hand by an end face of a preferably needle-shaped injection valve member 62 , The control room 60 is by a in the valve piece 56 trained inlet throttle 64 supplied with fuel under system pressure. The injector body 12 of the fuel injector 10 is via a high pressure connection 66 with an in 1 not shown high pressure source such as a high-pressure accumulator space (common rail) acted upon by fuel under system pressure.

This in 1 illustrated solenoid valve 14 includes a two-piece armature assembly. This means that the anchor plate 40 in relation to the anchor bolt 44 represents a relative to this movable separate component. When opening the closing element 52 by energizing the magnetic coil 30 of the solenoid valve 14 becomes the anchor plate 40 through the magnetic coil 30 dressed. The anchor plate 40 is over the lock washer 36 and this enclosing locking sleeve 34 with the anchor bolt 44 connected and is when energizing the solenoid 30 also pulled up. This will be the closing element 52 from his seat 54 moved and the drain throttle 58 in the valve piece 56 open. This will be the control room 60 depressurized and that preferably needle-shaped injection valve 62 moves upwards and gives at the combustion chamber end of the fuel injector 10 free formed injection ports.

For closing the closing element 52 is the energization of the solenoid 30 of the solenoid valve 14 interrupted, leaving the anchor plate 40 from the de-energized solenoid 30 drops. The anchor plate 40 and the anchor bolt 44 be by the magnetic core 26 enclosed valve spring 32 pressed down. This also makes the closing element 52 back in his seat 54 pressed and the pressure relief of the control room 60 by closing the outlet throttle 58 completed.

During the anchor bolt 44 after closing by the valve spring 32 the closing element 52 in his seat 54 presses, the anchor plate can 40 because of their longer path, the overstroke, designed against the cup over-travel spring 42 to move and resonate in relation to these. During the stroke of the anchor bolt 44 is on the order of about 40 microns, the stroke is including the overstroke of the anchor plate 40 between 50 and 70 μm. After closing the anchor bolt 44 finds a ringing of the anchor plate 40 instead, this through the over-travel spring 42 at its upper stop, ie the lock washer 36 is created.

The representation according to 2 the solution according to the invention can be seen with a displaced point of application of the valve spring.

The representation according to 2 can be seen that the anchor guide 46 at a clamping point 70 between the magnet sleeve 22 that the magnetic core 26 encloses and an edition 72 on the injector body 12 is fixed. The anchor guide 46 includes an annular surface 80 , which is a first end face 82 and second end face 84 having. The anchor bolt 44 is from the guide section of the anchor guide 46 enclosed and movable relative to this. From the illustration according to 2 can be further seen that the valve piece 56 by means of a clamping nut 46 inside the injector body 12 of the fuel injector 10 is fixed. Analogous to the representation according to 1 is on the valve piece 56 the seat 54 for the closing element 52 educated. The closing element 52 is partly from the Schließele management leadership 50 enclosed. The closing element guide 50 in turn is located on an annular surface 78 on the valve piece 56 assigning end of the anchor bolt 44 ,

Unlike the in 1 The solution according to the prior art is the valve spring 32 according to the invention proposed solution on the second end face 84 the ring surface 80 the anchor guide 46 and the ring surface 78 at the anchor bolt 44 above the closing element guide 50 ,

The ring surface 80 includes those already related to 1 described holes 48 to drain the over the opened drain throttle 58 reduced control amount in the direction of the low-pressure side return 18 through the through hole 28 of the magnetic core 26 to ensure. In the solution according to the invention, the overstroke spring is supported 42 that are relative to the anchor bolt 44 movable anchor plate 40 loaded and against the lock washer 36 urges, at the first end face 82 the ring surface 80 the anchor guide 46 from. This is preferred using a 1st shim 74 in the area of the clamping point 70 with regard to their position in the injector body 12 of the fuel injector 10 fixed. By the solution proposed by the invention, the force application point of the valve spring 32 in the lower area of the anchor bolt 44 , based on the axial extent in the injector body 10 , postponed. The positioning of the valve spring 32 offers the advantage that the valve spring 32 aligns itself centering and independent of the installation tolerance of the magnetic core 26 and the manufacturing tolerance of running in this through hole 28 (see. 1 ). By inventively proposed solution acts the valve spring 32 on top of the ring surface 78 at the bottom of the anchor bolt 44 , so that the force application point in comparison to the solution according to 1 around the axial length of the anchor bolt 44 moved down. This solution can drastically reduce the introduction of shear forces into the anchor assembly from anchor bolts 44 and anchor guide 46 be achieved. This leads to a more stable friction conditions within the armature assembly 40 . 44 . 46 and on the other to an improved alignment of the valve spring 32 within the armature assembly 40 . 44 . 46 , The installation position of the valve spring 32 the proposed solution according to the invention is no longer following the positioning of the magnetic core 26 in the fuel injector, but only on the tolerance between the anchor bolt 44 and the anchor guide 46 ,

The in 2 Following proposed solution according to the invention following the force application point of the valve spring 32 to the lower end of the anchor bolt 44 in the area of its annular surface 78 laid. The armature stroke can through the 1st shim 74 in the area of the clamping point 70 between the ring surface 80 the anchor guide 46 and the edition 72 on the injector body 12 be set. About another, 2nd shim 75 can the residual air gap between the anchor plate 40 and that of the magnet sleeve 22 enclosed magnetic core 26 be set. The 2nd shim 75 is preferably located between the upper end surface of the annular surface 80 and the magnet sleeve 22 , The through the valve spring 32 Spring force generated is the distance of the contact surfaces of the valve spring 32 , ie from the distance of the second end face 84 the ring surface 80 the anchor guide 46 to the top of the ring surface 78 in the lower end of the anchor bolt 44 dependent. If the manufacturing tolerances are accurate enough, an adjustment of the valve spring force by the interposition of the shim 74 omitted. In general, however, it should be noted that an adjustment of the spring force of the valve spring 32 is made. The tolerance with respect to the valve spring 32 Applied spring force is between + -1 microns. The tolerance chain consists of the tolerance of the armature stroke of + -5 μm, the manufacturing tolerance of the anchor plate 40 of + -15 μm and the manufacturing tolerance of the valve spring 32 of + -50 μm together. Add up results in a summed tolerance of + -70 microns. With an assumed spring stiffness of the valve spring 32 of C = 50 N per mm and an added tolerance of + -70 μm results in a spring force tolerance of + -5 N, by choosing a suitable shim 74 to compensate.

In the 2 shown, relative to the anchor bolt 44 movable anchor plate 40 acting over-stroke spring 42 is located below the anchor plate 40 and positions it against the lower end face of the magnetic core 26 who is the one in turn 2 not shown magnetic coil 30 encloses. The setting of the overtravel of the anchor plate 40 can be done with identical shims as in the known from the prior art solution according to 1 be used.

The setting of the residual air gap between the upper end face of the anchor plate 40 and the assigning this end face of the magnetic core 26 which the magnetic coil 30 encloses takes place in principle in a known manner.

Claims (10)

Fuel injector ( 10 ) with a solenoid valve ( 14 ) for actuating a closing element ( 52 ) for pressure relief of an injection valve member ( 62 ) control room ( 60 ), with one on an anchor bolt ( 44 ) movably received anchor plate ( 40 ) as well as an anchor guide ( 46 ), the anchor bolt ( 44 ) of a valve spring ( 32 ) of the solenoid valve ( 14 ) is acted upon, characterized in that the valve spring ( 32 ) between the anchor bolt ( 44 ) and the anchor guide ( 48 ) is recorded. Fuel injector according to claim 1, characterized in that the valve spring ( 32 ) on an annular surface ( 80 ) the anchor guide ( 46 ) and an annular surface ( 78 ) of the anchor bolt ( 44 ) is supported. Fuel injector according to claim 1, characterized in that the armature guide ( 46 ) includes a guide portion which a valve piece ( 46 ) assigns. Fuel injector according to claim 1, characterized in that the armature guide ( 46 ) at a clamping point ( 70 ) between a magnetic sleeve ( 22 ) and an injector body ( 12 ) is attached. Fuel injector according to claim 4, characterized in that the armature stroke of the anchor bolt ( 44 ) at the clamping point ( 70 ) via at least one shim ( 74 ) is defined. Kraftstsoffinjektor according to claim 2, characterized in that the anchor plate ( 40 ) by an overstroke spring ( 42 ) is applied, which on a first end face ( 82 ) of the annular surface ( 80 ) the anchor guide ( 46 ) is supported. Fuel injector according to claim 3, characterized in that the valve spring ( 32 ) self-centering on the guide portion of the armature guide ( 46 ) is recorded. Fuel injector according to claim 1, characterized in that an annular surface ( 78 ) of the anchor bolt ( 44 ) as a support surface for the valve spring ( 32 ) and a closing element guide ( 50 ). Fuel injector according to claim 1, characterized in that a magnetic core ( 26 ) of the solenoid valve ( 14 ) a through hole ( 28 ), which has a funnel-shaped inlet region over which one of the control room ( 60 ) controlled tax amount a low-pressure return ( 18 ) flows in. Use of a fuel injector 10 , according to one or more of claims 1 to 9 in a high-pressure accumulator injection system, in particular for self-igniting internal combustion engines.