EP1967726B1 - Magnetic valve injector - Google Patents

Description

State of the art

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 injection system. Via the fuel pressure in the control chamber, a stroke movement of a valve piston is controlled, with which an injection opening of the injection valve is opened or closed. The solenoid valve comprises an electromagnet, a movable armature and a valve member which is moved with the armature and acted upon by a valve closing spring in the closing direction and which cooperates with the valve seat of the solenoid valve and thus controls the fuel drain from the control chamber.

In known solenoid valves, the swing occurring during operation of the armature and / or bouncing of the valve member has a disadvantageous effect. By a ringing of the impinging on the valve seat anchor plate this assumes an undefined position. Thus, in subsequent injections with the same control to different opening times of the solenoid valve and thus to a dispersion of the injection start and the injection quantity. According to DE 196 50 865 A1 and DE 197 08 104 A1 the armature of the solenoid valve is designed as a two-part armature, so as to reduce the moving mass of the unit armature / valve member and thus the bouncing kinetic energy. The two-piece anchor comprises an anchor bolt and an anchor plate slidably received on the anchor bolt against the force of a return spring in the closing direction of the valve member under the action of its inertial mass, which is secured to the anchor bolt by means of a lock washer and a securing sleeve surrounding it. The locking sleeve and the locking washer are enclosed by the magnetic core, resulting in an increased space requirement and resulting in a higher diameter in the magnetic core. Due to the higher diameter in the magnetic core in turn results in a limitation of the magnetic flux.

By the DE 199 55 663 A1 a fuel injector with a solenoid valve is known, via which an armature assembly is actuated, which comprises at least one anchor plate and an anchor bolt, and with a valve piece, in which a control chamber is executed. The valve piece has a neck in which the anchor bolt is guided along a guide length.

Disclosure of the invention

According to the invention it is proposed to use a modified valve piece and the design of the anchor assembly comprising the anchor bolt and the anchor plate to simplify considerably. It is proposed to make the top of the valve piece such that it also accommodates a dial as a so-called Überhubscheibe in addition to the function of the anchor bolt guide, which is guided on the anchor bolt and with which the downward movement of the anchor plate is limited. By this arrangement of the over-stroke disc can be dispensed with a safety sleeve, which prevents hitherto used in the embodiments of fuel injectors from wandering the Überhubscheibe.

The types of fuel injectors used so far are relatively expensive. There must be a valve seat in the valve member in the form of a cone, a long guide surface along the anchor bolt, a guide surface in the armature guide and a guide surface in the anchor plate by means of the machining process, usually the grinding, produced. In addition, the quality of the guide of the anchor plate by an indirect guidance over the anchor bolt is relatively low. The power transmission from the anchor plate to the anchor bolt is done via a sickle disc with which an overstroke is usually set. The asymmetric power transmission leads to tilting and wear at the contact point. The manufacture of the height-ground sickle plate is still extremely complex and the side-mounted mounting very complicated.

In the case of current series products, the problem arises that the valve spring exerting a closing force on the anchor bolt introduces lateral force components into the assembly of anchor plate and anchor bolt. Due to the guiding play between the armature guide and the anchor bolt, this leads to a tilting of the anchor bolt in the armature guide. With strong lateral force, this tilt can also be present in the upper position of the anchor bolt when energized electromagnet, since an anchor bolt stop can rest on one side. This part of the previously set anchor stroke, ie the movement of the anchor bolt during operation, not fully utilized. This in turn leads to a lower injection quantity of fuel into the combustion chamber of an internal combustion engine. Added to this is the friction of the anchor bolt in the anchor guide, which also influences the movement of the anchor bolt. This friction increases with a larger tilt angle α, since the lever arm of the triggering force also increases. The point of application of the valve spring has a relatively large distance to the upper end of the Ankerfiihrung. This creates at the top and at the bottom of the anchor guide very high punctually acting forces on the anchor bolt, which additionally reinforce the friction and thus slow the movement of the anchor bolt. However, the speed with which the anchor bolt moves, ie the opening and closing of the valve ball, has a very large influence on the amount of fuel respectively introduced into the combustion chamber of the internal combustion engine.

A concentricity of valve seat to anchor bolt guide allows a simplification in terms of production technology, since these assemblies, ie valve seat and anchor bolt guide, can be machined in one operation, in particular by way of grinding. Therefore, the ball guide, which is at the bottom of the anchor bolt according to the solution DE 196 50 865 A1 is provided and has the function to compensate for the misalignment of leadership to seat omitted.

At the bottom of the anchor bolt, a concave surface for receiving a spherical closure member can be provided with omission of the ball guide.

In a preferred embodiment, the anchor plate may be made as a flat disc which is mounted from below on the anchor bolt and is supported on a shoulder formed on the anchor bolt. The disc can be made by punching or by double-plan grinding. The top and the bottom are identical, so that a position-independent mounting of the anchor plate on the anchor bolt can be realized. The upper stop for the anchor plate can be represented by a flat paramagnetic disc on the magnetic core. The thickness of this preferably paramagnetically formed disc is chosen so that it adjusts the residual air gap within the magnetic circuit.

In fuel injectors whose preferably needle-shaped injection valve member is actuated by an electromagnet, the downward movement of the armature plate is limited after closing the valve for pressure relief of a control chamber usually by the stop of the anchor plate on the top of the armature guide. An in the downward movement of the armature plate after closing to the diverted Freiweg is also referred to as overstroke. This overstroke is advantageously set by a rotationally symmetrical shim, which is placed on the top of the valve piece, in which the pressurized control chamber is formed. The Überhubscheibe, ie the rotationally symmetrical shim also limits the tilting of the anchor plate on the anchor bolt by contact of the armature plate on its outer diameter. In contrast to previously used embodiments of the over-stroke disk, the over-stroke disk according to the proposed invention is relatively simple and in particular does not require a safety sleeve which, in previously used embodiments of fuel injectors, prevents the over-stroke disk from migrating out.

Brief description of the drawings

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

Figur 1

einen Schnitt durch eine erfindungsgemäß vorgeschlagene erste Ausführungsform der Ankerbaugruppe und

Figur 2

eine modifizierte Ausführungsform einer Ankerbaugruppe mit geändertem Rücklaufweg für die aus einem Steuerraum abgesteuerte Kraftstoffmenge.

It shows

FIG. 1

a section through an inventively proposed first embodiment of the armature assembly and

FIG. 2

a modified embodiment of an armature assembly with a modified return path for the controlled from a control room amount of fuel.

embodiments

The representation according to FIG. 1 is a section through a first embodiment of the present invention proposed fuel injector refer.

The representation according to FIG. 1 a fuel injector 10 can be removed, which is actuated by means of a solenoid valve 12. The solenoid valve 12 is received in the upper region of an injector body 14 of the fuel injector 10. The fuel injector 10 is designed substantially symmetrically to an axis 18.

The magnetic valve 12 includes a magnetic sleeve 20. The magnetic sleeve 20 encloses a magnetic core 22, which in turn receives a magnetic coil 24. The magnet sleeve 22 accommodating the magnetic core 22 and the magnet coil 24 is screwed to the injector body 14 by means of a union nut 26 at a screw connection 28. In this case, the magnet sleeve 20 is sealed on its outer side by means of a sealing ring 30 against the injector body 14.

The solenoid valve 12 includes a valve spring 32. The valve spring 32 is received substantially in a through hole of the magnetic core 22 and supported on the one hand on an armature assembly 34, in particular on the upper side of an anchor bolt 46 and on the other hand against a closing the solenoid valve 12 lid. The solenoid valve 12 also includes the previously mentioned armature assembly 34. The armature assembly 34 includes in addition to the previously mentioned valve spring 32, an anchor plate 40, a Überhubscheibe 44 and an anchor bolt 46 which is guided within a valve member 50. In addition to the valve seat, the upper side of the valve piece 50 also performs the function of guiding the anchor bolt 46 of the armature assembly 34 in the axial direction. This is on the valve piece 50, a neck 92 is formed, which runs parallel to the longitudinal extent of the anchor bolt 46, forming an annular gap 80, as seen in the axial direction. The neck 92 of the valve member 50 has an annular surface 94 on which in turn the over-stroke disk 44 is placed.

From the illustration according to FIG. 1 shows that above the over-stroke plate 44, the anchor plate 40 of the armature assembly 34 extends, which has at least one opening 42 to allow passage of fuel discharged from a control chamber 54 in the direction of the low-pressure side sequence of the fuel injector 10.

The anchor bolt 46 of the armature assembly 34 according to the embodiment of FIG FIG. 1 includes a here formed spherical closure member 66. The optionally at the lower end face of the anchor bolt 46 with the interposition of a closing element guide received, preferably spherical shaped closure member 66 cooperates with the seat 52 which is formed in the valve piece 50. Below the seat 52, which may be formed as a flat seat, conical seat or the like, extends within the valve piece an outlet throttle 58. About the outlet throttle 58 is also formed in the valve piece 50 control chamber 54 drucklastbar.

FIG. 1 shows that the control chamber 54 is continuously supplied with fuel at a system pressure level via an inlet throttle 56 from a high-pressure chamber 74, which in turn is subjected to fuel under system pressure. About the pressurization or pressure relief of the control chamber 54 within the valve piece 50, a preferably needle-shaped injection valve member 62 is actuated. The high-pressure chamber 74 within the injector 14 of the fuel injector 10 is sealed against the low pressure via a sealing ring 60, which is preferably made as a PTFE component.

The representation according to FIG. 1 Furthermore, it can be seen that the valve piece 50 with neck 92 formed thereon, in which the anchor bolt 46 is guided, is fastened in the injector body 14 of the fuel injector 10 by means of a valve screw 64. About the valve screw 64, the valve member 50 is pressed on its contact surface in the injector 14 and sealed low pressure side.

From the illustration according to FIG. 1 goes further, that at the lower end face 36 of the magnetic core 22 a simply formed residual air gap disc 38 is located. This opposite is - in the de-energized state of the solenoid 24 - the anchor plate 40 of the armature assembly 34. The anchor plate 40, in the at least one opening 42 is mounted on the underside of the anchor bolt 46 and abuts against an annular bolt 76 formed on the anchor bolt 46. Top and bottom of the anchor plate 40 are identical, so that a position-independent mounting and the production can be realized by punching and double-plan loops. At the armature plate 40 of the armature assembly 34 opposite end side of the magnetic core 22 is the residual air gap disc 38, which is formed as a flat paramagnetic disc. The thickness of the residual air gap disc 38 significantly influences the residual air gap within the magnetic circuit.

At the in FIG. 1 illustrated embodiment of the fuel injector 10, the downward movement of the armature plate 40 is limited by the Überhubscheibe 44 on the end face 94 of the neck 92 of the valve piece 50 after closing of the solenoid valve. The Überhubscheibe 44 also limits the tilt of the armature plate 40 on the anchor bolt 46 by contact of the armature plate 40 at its outer diameter. Those in the embodiment in FIG. 1 shown Überhubscheibe 44 requires no locking sleeve. Furthermore, in the in FIG. 1 illustrated embodiment of the solenoid valve assembly to dispense with a separate component for the realization of the armature guide, since the leadership of the armature, in particular of the anchor bolt 46, takes place through the neck 92 of the valve member 50. For the sake of completeness, it should be mentioned that the annular gap 80 between the jacket surface of the anchor bolt 46 and the inside of the neck 92 has at least one opening 48, via which the control quantity exiting the control chamber 54 when the ball-shaped closing element 66 opens into the low-pressure region of the fuel injector 10 can flow out. Via the at least one opening 48 in the neck 92 of the valve piece 50, the annular gap 80 and a valve chamber 88 in the interior of the solenoid valve assembly are hydraulically connected to one another. In the in FIG. 1 1, the ball-shaped closing element 66 is received directly on the lower end face of the anchor bolt 46, so that a ball guide for the here spherically formed closing element 66, which would compensate for an offset of the guide and seat 52, can be dispensed with. This is because the concentricity of the valve seat 52 to the anchor bolt guide 92 is excellent, since the valve seat 52 and the anchor bolt guide in one operation by a machining process such. As the grinding can be made.

The valve piece 50 is screwed by means of the valve screw 64 in the injector 14. The closing element 66 is inserted into the seat 52, which is formed in the valve piece 50. On the upper side of the valve piece 50 is the over-stroke disk 44, which serves as a lower stop for the anchor plate 40. The anchor bolt 46, which has at least one bevel 72 on its lateral surface, via which fuel enters the annular gap 80, is inserted into the valve piece 50 and thereby takes the Überhubscheibe 44 and the armature plate 40 with at least one opening 42 at its outer diameter. On the armature plate 40 in turn is the residual air gap disc 38, which limits the upper stop of the armature plate 40 by this is supported in operation on the lower end side of the magnetic core 22 of the solenoid valve assembly of the fuel injector 10. The anchor bolt 46 is acted upon by the valve spring 32 indicated by reference numeral 32 in the closing direction with a closing force.

In preparation for an injection event, a small current is applied to the solenoid coil 24 received in the magnetic core 22 of the solenoid valve assembly. The resulting magnetic field is sufficient to apply the anchor plate 40 to the shoulder, ie the stop 76 on the anchor bolt 46, which does not yet lead to an opening of the valve. Subsequently, a starting current is applied to the magnetic coil 24. The magnetic force generated by the attraction current attracts the armature plate 40, which is supported on the stop 76 of the anchor bolt 46 and leads to the opening of the valve. The ball-shaped closing element 66 on the lower end face of the anchor bolt 46 is lifted in the valve piece 50 by the pressure applied from below from its seat 52. The armature plate 40 abuts on the magnetic core 22 via the residual air gap disk 38. To keep open the valve, ie to maintain the distance between the moving from the seat 52 closing member 66 and the seat 52 is switched to a lower holding current with which the solenoid 24 is now energized. After the complete shutdown of the current, the magnetic field degrades until the anchor plate 40 moves back in the closing direction. Once in the embodiment according to FIG. 1 Ball-shaped closure member 66 meets in its seat 52, the anchor plate 40 detaches from the stop 76 at the upper end of the anchor bolt 46 and moves further in the closing direction until it strikes with its underside resting on the annular surface 94 of the neck 52 Überhubscheibe 44.

In the in FIG. 1 In the embodiment shown, the discharge of the control quantity diverted from the control chamber 54 takes place as follows: At least one flattening 72 or a bevel or the like is located on the lateral surface of the anchor bolt 46 of the armature assembly 34, so that within the armature guide surface, ie through the annular gap 80 between the outer surface of the armature Anchor bolt 46 and the inner peripheral surface of the neck 92 diverted tax amount in the valve chamber 88, that flows to the low pressure side of the solenoid valve assembly. About this at least one opening 48 in the neck 92 of the valve member 50, the discharged at pressure relief of the control chamber 54 from this control amount in the armature space, ie the valve chamber 88, and from there flow through the at least one opening 42 in the armature plate 40 to the return.

FIG. 2 shows a further embodiment of the present invention proposed valve piece.

From the illustration according to FIG. 2 shows that according to this embodiment of the valve member 50 on the anchor bolt 46 of the armature assembly 34 no bevel 72 or no flattening is formed. Instead, located at the bottom, the seat 52 facing end face of the anchor bolt 46 is a spherical cap 82. The spherical cap 82 forms a receptacle for in accordance with the embodiment FIG. 2 Spherically shaped closing element 66, with which the seat 52 is closed in the valve piece 50. Below the seat 52 opens in the valve piece 50, the outlet throttle 58, via which the in FIG. 2 not shown control chamber 54 is depressurized. The at the pressure relief in the embodiment according to FIG. 2 not shown control chamber from this outflowing amount flows into a spherical cap 82 within the valve member 50 surrounding space. From this, at least one bore 86 extends to the valve chamber 88 of the solenoid valve assembly. The at least one bore 86, which connects the hydraulic space which surrounds the spherical cap 82, with the valve chamber 88 extends in the valve piece 50 in FIG. 2 indicated obliquely, so that the wall thickness of the neck 92 of the valve member 50 is not affected by the course of the at least one bore 86 in the valve piece 50. As shown in the illustration FIG. 2 As can be seen, due to the inclination of the at least one bore 86 in the valve piece 50, these open at the bottom of the valve chamber 88 in the low-pressure region of the solenoid valve assembly. From the illustration according to FIG. 2 goes moreover, that according to this embodiment, the armature plate 46 slidably received anchor plate 40 analogous to the embodiment according to FIG. 1 has at least one opening 42, but is acted upon by an armature spring 84. The armature spring 84 is supported on the one hand on the underside of the anchor plate 40 and on the other hand at the bottom of the valve chamber 88 from.

As in the embodiment according to FIG. 1 already shown, is also in the embodiment according to FIG. 2 the top of the anchor plate 40 to the stop 76 of the anchor bolt 46 at. The axis of symmetry of the anchor bolt 46 of the armature assembly 34 is identified by reference numeral 18.

From the embodiment according to FIG. 2 shows that above the top of the anchor plate 40, the residual air gap disc 38 is attached to the underside of the magnetic core 22. The thickness of the residual air gap disk 38 is defined analogously to the embodiment according to FIG FIG. 1 the height of the residual air gap between the bottom of the residual air gap disc 38 and the top of the anchor plate 40th

This in FIG. 2 illustrated valve member 50 includes the neck 92, on the annular surface 94, the over-stroke disc 44 rests. An annular gap 80 extends between the lateral surface of the anchor bolt 46 and the inner peripheral surface of the neck 92. Reference numeral 78 marks the guide length along which the anchor bolt 46 of the armature assembly 34 is guided in the valve piece 50 or neck 92 formed thereon. The guide length 78 extends from the lower end face of the anchor bolt 46, ie above the spherical cap 82, to the beginning of the annular gap 80 between the lateral surface of the anchor bolt 46 and the inner peripheral surface of the neck 52. In the embodiment according to FIG FIG. 2 the opening 48 in the neck 92 may also be omitted.

With reference numeral 90, the end face of the valve member 50 is referred to, on the one hand, the armature spring 84 is supported and on the other hand, the at least one bore 86 opens for discharging the control amount. By the at least one bore 86 in the valve member 50, the control amount does not flow along the guide length 78 of the anchor bolt 46, but is passed through the at least one bore 86 in the valve member 50 directly into the valve chamber 88 and can from there via the at least one opening 42 in the armature plate 40 flow in the return. In the embodiment according to FIG. 2 In addition, the armature spring 84 is introduced, which presses the armature plate 40 up against the stop 76 of the anchor bolt 46 instead of the low current in preparation for an injection process. In the embodiment according to FIG. 2 is also located on the lower end face of the anchor bolt 46 of the armature assembly 34, the spherical cap 82, which can then be used if the offset between the ball guide on the anchor bolt 46 to the seat 52 in the valve piece 50 is too large and thereby the tightness should be impaired.

Claims (9)

1. Fuel injector (10) having a solenoid valve (12) which serves to actuate an armature assembly (34) which comprises at least one armature plate (40) and one armature pin (46), and also having a valve piece (50) in which a control chamber (54) is formed, with the valve piece (50) having a neck (92) in which the armature pin (46) is guided along a guide length (78), characterized in that an overstroke disc (44) which is guided on the armature pin (46) bears against an end side (94) of the neck (92) facing towards the armature plate (40).
2. Fuel injector according to Claim 1, characterized in that the armature plate (40) is held on the armature pin (46) between the overstroke disc (44) and an annular stop (76).
3. Fuel injector according to Claim 1, characterized in that a residual air gap disc (38) is held between a magnet core (22) of the solenoid valve (12) and the armature plate (40).
4. Fuel injector according to Claim 3, characterized in that the residual air gap disc (38) is produced from paramagnetic material.
5. Fuel injector according to Claim 1, characterized in that the neck (92) of the valve piece (50) has at least one opening (48) which serves to hydraulically connect an annular gap (80) between the armature pin (46) and the neck (92) to a low-pressure-side valve chamber (88).
6. Fuel injector according to Claim 1, characterized in that the armature pin (46) has, on its lateral surface, at least one flattened portion (72) whose axial extent on the armature pin (46) exceeds the guide length (78) of the armature pin (46) in the neck (92).
7. Fuel injector according to Claim 1, characterized in that the valve piece (50) has a seat (52) for a closing element (66) which is guided on the armature pin (46) directly or in a spherical cap (82).
8. Fuel injector according to Claim 1, characterized in that the valve piece (50) has at least one bore (86) which opens out at an end side (90) of the valve piece (50) and hydraulically connects a hydraulic chamber above the seat (52) to a valve chamber (88) of the solenoid valve (12).
9. Fuel injector according to Claim 1, characterized in that the armature plate (40) has identical top and bottom sides and also comprises at least one opening (42).

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