EP2252786B1 - Sealed electric feedthrough - Google Patents

Description

State of the art

DE 196 50 865 A1 refers to a solenoid valve for controlling the fuel pressure in a control chamber of an injection valve, such as a common rail injection system, for supplying fuel to self-igniting internal combustion engines. About the fuel pressure in the control chamber, a stroke movement of a valve body is controlled with 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 and cooperating with the valve seat of the valve member to control the fuel output from the control chamber.

In common-rail fuel injectors, which are actuated by means of a solenoid valve, the electrical contact of the solenoid must be led out of a space filled with fuel under reflux pressure to the outside. This is usually done through a hole or more holes in the magnet sleeve. An important task of this implementation is in addition to the electrical insulation of the coil and contacts with respect to the injector, the hydraulic seal the implementation. It must be safely prevented that fuel escapes through this passage to the outside. Although the electrical contact behind the implementation is again encapsulated in plastic. The plastic extrusion and the contact lugs then together form the electrical connector of the fuel injector. However, there is always a very small gap between the electrical supply line and the plastic of the encapsulation, which can not be avoided. Due to this, fuel that leaks from the above-mentioned implementation, always get over this narrow gap in the electrical connector of the fuel injector, from where he can get over the wiring harness to the control unit. This can cause damage to the controller.

Usually, the bushings are sealed with an O-ring joined to the coil pins. These O-rings are first pushed over the coil pins and then inserted with the coil pins from below into the corresponding bore of the sleeve. They come under radial stress and seal both with respect to the bore wall and against the pin jacket surface safely. To prevent the O-ring from passing through the hole, the hole is tapered upwards. This can be achieved either via a step or via a conical bore shape. To ensure that the O-ring is inserted into the bore, the coil pin is encapsulated in its lower part with plastic, which forms a so-called "dome" above the Spulenumspritzung and also avoids touching the coil pins with the magnetic core.

Since the magnetic core is usually supported on a shoulder in the sleeve, the sleeve has hitherto been made in two parts, i. from an actual sleeve and from a drain neck. The magnetic core with coil was first inserted from above into the sleeve until it rested on the shoulder. Then the drain neck was placed on top and held down with a defined force. Thereafter, discharge spout and sleeve were crimped together and thereby fixed the magnet in its position. The feedthroughs of the coil pins were incorporated in this case in the outlet pipe. If the sleeve is to be made in one piece in a cost effective manner, this has the consequence that the magnetic core must be inserted from below into the sleeve. It is particularly advantageous if the inner contour of the sleeve and the outer contour of the core are not rotationally symmetrical, but have a radial contour. First, the core is inserted from below into the sleeve in an angular position in which sleeve and core do not overlap when viewed from below. Between core and sleeve there is a spring element which is suppressed with a defined mounting force. If the magnetic core is inserted so deeply into the magnet sleeve that its end face is located above the associated bearing surface in the sleeve, the core is rotated by a defined angle (for example 45 °) with respect to the sleeve. As a result, the areas of large outer diameter of the core interact with those small inner diameters of the support surface. When removing the mounting force, these areas are based on each other, so that the core is now fixed in the sleeve.

Since the magnetic core is twisted during assembly, the magent coil may not yet be mounted in the magnetic core, but may only be joined to the magnet core from below after mounting and aligning it. Since the outer diameter of the O-rings is larger than the recess for the pin dome in the magnetic core, the solenoid can only be mounted without O-rings. Alternatively, it is possible to perform the sealing of the bushings not with O-rings, but these bushings after Pour out the assembly of the complete magnet assembly with adhesive and seal in this way. However, this variant involves some risks that are critical in view of the error sequence, such as the outward leakage of fuel: Although the adhesive initially filled in the liquid state, the entire space between the sleeve and pin, but then hardens. If it then comes to a delay in the interconnected components - whether by the action of external forces (screws, magnetic head, holding body, etc.) or by different thermal expansions - so can the initially tight connection between the adhesive plug and the magnet sleeve or pin again lost, so that again creep gaps can form for the fuel. The Klebstoffpfropf is also constantly exposed to the fuel under some high temperature. When changing fuel quality, the chemical resistance of the adhesive to the fuel must be guaranteed for up to 15 years. Due to these risks outlined above, adhesive pin-sealing is risky.
A sealing solution for a piezoelectric actuator is from the EP-A-1628 015 known.

Presentation of the invention

By means of the inventively proposed invention, a reliably functioning sealing of the feedthroughs of electrical contacting pins from the housing of the fuel injector can be realized without recourse to an adhesive variant which involves the risks listed above. According to the invention, it is proposed to introduce a sealing element, which is similar to an O-ring, into the pin leadthrough, which, in contrast to O-rings inserted in advance in the leadthrough, allows a subsequent mounting of the magnet coil. An assembly of simply introduced in advance into the feedthrough holes O-rings is eliminated because they deform without skewing by the Kontaktierungspin the solenoid skew in the feedthrough bore and so neither a safe sealing function nor a safe mountability of the solenoid is to ensure.

A sealing element made of elastic material can be vulcanized into the leadthrough hole for the contacting pin for electrical contacting of the magnetic coil. Thus, the tightness of the magnet sleeve is already guaranteed. The inner diameter of the vulcanized sealing element is smaller than the diameter of the Kontaktierungspins for electrical contacting of the magnetic coil. Now, if the solenoid is mounted from the bottom, the Kontaktierungspins be pushed for electrical contacting of the magnetic coil through these openings of the previously vulcanized sealing elements. As a result, these sealing elements are biased in the radial direction by the introduced Kontaktierungspins and thereby seal at the Kontaktierungspins to the outside. This bias in the radial direction also causes a self-sealing of the guided through the magnet sleeve outward Kontaktierungspins, so that the tightness is guaranteed even if the built-up at the molecular level connection between the sealing element and magnetic sleeve surface disappears over time. Possible causes for this are temperature changes and occurring mechanical stress. The tightness is ensured by the radial bias of the vulcanized sealing element and not - as in the introduced adhesive - purely by the chemical bond between the surfaces of the sealing element and the surfaces of the magnet sleeve and the Kontaktierungspins. This achieves the safe representation of the seal over the entire product duration.

According to the invention, it is proposed that the vulcanized-in sealing elements not be designed with a small inner opening, but consistently. In this case, the thickness in the center is smaller than the thickness outside, and the sealing elements are designed such that the sealing element can be pierced there by the contacting pin of the magnetic coil with a small axial force. During assembly of the magnetic coil, the sealing elements are pierced at these thinned points and biased in the sequence thereof in the radial direction, so that they also seal to the electrical Kontaktierungspins the solenoid out.

The proposed solution according to the invention will be described below with reference to a fuel injector for actuation by means of a solenoid valve for a Hochdruckspeichereinspritzsytem (common rail), but can also be applied to other currently unclaimed motor vehicle components in which a leakage of medium to the outside must be prevented.

Brief description of the drawings

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

Figur 1

einen Schnitt durch einen Magnetkopf eines Magnetventils für einen Kraftstoffinjektor mit einer Abdichtung eines Kontaktierungspins mit einem O-Ring und mit einem Klebstoffeinspritzelement,

Figur 2

eine Unteransicht eines Magnetkopfes mit einteiliger Hülse und durch Verdrehung verriegelten Magnetkern,

Figur 3.1

ein einvulkanisiertes Dichtelement als Einzelteil,

Figur 3.2

ein einvulkanisiertes Dichtelement nach Montage der Magnetspule,

Figur 4.1

ein in eine Durchführung einvulkanisiertes, erfindungsgemäßes Dichtelement ohne Innenöffnung als Einzelteil und

Figur 4.2

ein einvulkanisiertes Dichtelement nach Montage der Spule.

It shows:

FIG. 1

a section through a magnetic head of a solenoid valve for a fuel injector with a sealing of a Kontaktierungspins with an O-ring and with an adhesive injection element,

FIG. 2

a bottom view of a magnetic head with one-piece sleeve and locked by twisting magnetic core,

Figure 3.1

a vulcanised sealing element as a single part,

Figure 3.2

a vulcanized sealing element after assembly of the magnetic coil,

Figure 4.1

a vulcanized into a bushing, inventive sealing element without internal opening as a single part and

Figure 4.2

a vulcanized sealing element after mounting the coil.

Embodiments of the invention

The representation according to FIG. 1 there is a group of magnets which includes a solenoid and is sealed outwardly in two different ways to prevent the escape of fuel from a fuel injector.

FIG. 1 shows in section a magnet group 10, which is accommodated in a magnetic sleeve 12 formed integrally here. The magnet sleeve 12 and the magnet group 10 are symmetrical to an injector axis 14 of an in FIG. 1 formed fuel injector, not shown. By means of the magnet group 10 of the fuel injector is actuated, that causes a pressure relief of a system under pressure control chamber.

The magnet sleeve 12 has a return 16, to which on the outside of the lateral surface 12, a return port 18 is aligned.

The magnet group 10 essentially comprises a magnetic core 20 and a magnetic coil 22 embedded in the magnetic core 20 FIG. 1 not shown anchor assembly assigning end face of the magnetic core 20 is shown in the illustration FIG. 1 designated by reference numeral 24.

As shown in the illustration FIG. 1 Furthermore, the magnetic coil 22 of the magnetic group 10 is electrically connected via a Kontaktierungspin 28. The contacting pin 28 can - as in FIG. 1 shown in the left half - sealed by an O-ring 32. The O-ring 32 is inserted into a passage 30 and employed by a plastic dome 36 to a shoulder of the magnet sleeve 12. However, this solution requires that the magnetic coil 22 must be moved during assembly in the magnetic head only in the axial direction and that the O-rings 32 are already pre-assembled on the coil pins.

In the right half of the in FIG. 1 illustrated embodiment, the contacting pin 28 is sealed to energize the magnetic coil 22 within the magnetic core 20 via a Klebstoffpfropfen 40. As long as the adhesive in the passage 30 is flowable, this penetrates into all the pores or small gaps of the magnetic sleeve 12 and seals them to the outside of the magnetic sleeve 12 back. However, as soon as the material of the adhesive plug 40 has hardened, microcracks may occur due to mechanical stresses and thermal expansions, which allow the escape of fuel from the low-pressure region 38 to the outside of the magnet group 10. Although it is through the adhesive plug 40, as in FIG. 1 A seal can be achieved, but there is a considerable risk that the sealing effect will be lost over the life of the product.

The representation according to FIG. 2 is the view of a magnet assembly 10 can be seen from the bottom.

As FIG. 2 shows, the magnetic sleeve 12 - see. Representation according to FIG. 1 - Along a circumference of a mounting hole a number of attacks 42. These attacks 42 are formed in the radial direction so that they exceed the diameter of the magnetic core 20 to be mounted. The magnetic core 20, which is, however, inserted from the bottom into the magnet sleeve 12 and rotated in a direction of rotation 56, has on its outside a number of wing-shaped widenings. These wing-shaped spacers are inserted into the magnet sleeve 12 in a first angular position 52 of the magnet core 20 with respect to the magnet sleeve 12. The insertion of the magnet core 20 into the magnet sleeve 12 is followed by a rotation 56 of the magnet core 20 in the clockwise direction 56, as a result of which the wing-shaped projections on the circumference of the magnet core 20 are overlapped with overlaps 42 (cf. FIG. 1 ) of the magnetic sleeve 12 are brought. As a result of the action of the spring element 26 designed as a plate spring, the magnetic core 20 is pressed against the radial projections of the magnet sleeve 12 -without a magnet coil 22.

After assembly of the magnetic core 22 as shown in FIG FIG. 2 there is an insertion of the solenoid 22 from the bottom. The magnetic coil 22 has the Kontaktierungspins 28 to be contacted electrically, which the bushings 30 -. Representation according to FIG. 1 - Pass and be contacted on the outside of the magnet sleeve 12 of the magnet group 10 electrically. For electrical contacting of the Kontaktierungspins 28 connector lugs are preferably used, which are welded to the Kontaktierungspins 28, soldered or electrically connected in some other way. A seal in this solution using O-rings 32 would be only then possible if the magnetic core 20 have passages which are larger than the outer diameter of the mounted on a coil pin 28 O-ring 32. Such large recesses in the magnetic core 20, however, are counterproductive to achieve the desired magnetic force and therefore to avoid as far as possible.

The representation according to Figure 3.1 to remove a vulcanized elastic sealing element.

As the representation of Figure 3.1 can be removed, a vulcanized sealing element 34 is received in the magnet sleeve 12 in the region of the passage 30. The vulcanized sealing element 64 is preferably vulcanized in the context of a diameter transition of the bushing 30 against the paragraph resulting from the diameter transition and fixed in this manner within the bushing 30.

An outer side of the magnet sleeve 12 is designated by reference numeral 62, while an inner side 60, ie the side of the magnetic sleeve 12 facing the low-pressure region 38, is designated by reference numeral 60. As Figure 3.1 The inner diameter of the inner opening 66 is dimensioned to be smaller than the outer diameter of the Kontaktierungspins 28 through which the magnetic coil 22 of the magnetic group 10 is electrically contacted after mounting in the magnet sleeve 12. This in the illustration according to Figure 3.1 In the diameter transition of the bushing 30 vulcanized sealing element 64 comprises sealing lips 68, which nestle sealingly on the lateral surface 36 during assembly of the contacting pin 28. Due to the difference in diameter between the inner opening 66 of the sealing element 64 vulcanized into the bushing 30 with respect to the outer diameter of the contacting pin 28, a radial prestress 70 of the material of the sealing element 64 vulcanized into the bushing 30 results.

The representation according to Figure 3.2 is the vulcanized sealing element to remove in the assembled state of a Kontaktierungspins.

As Figure 3.2 shows, during assembly of the Kontaktierungspins 28 of the solenoid 22, a widening of the inner opening 66 of the vulcanized in the implementation 30 sealing element 64. The inner diameter of the vulcanized sealing element 64 is less than the outer diameter of the Kontaktierungspins 28 of the solenoid 22. Accordingly, when inserting the Kontaktierungspins 28 deflected in the passage 30 vulcanized in the sealing element 64 whose sealing lips 68 in the radial direction and exert in the radial direction a radial prestress 70 within a sealing length 72 from. The Sealing length 72, which results during insertion of the contacting pins 28 into the sealing element 64 vulcanized into the magnetic sleeve 12, is essentially of the order of magnitude of the diameter of the vulcanized sealing element 64.

As Figure 3.2 It can also be seen that the sealing element 64 vulcanized into the bushing 30 rests against a shoulder defined by a diameter jump of the bushing 30 and is consequently secured in the axial direction - with respect to the insertion direction of the contacting pins 28 - and positioned in the defined position. If the contacting pins 28 are inserted into the sealing element 64 vulcanized into the magnet sleeve 12, the sealing lips 68 are widened radially so that they conform to the lateral surface 76 of the contacting pins 28 of the magnet coil 22 along a sealing length 72. Depending on the length of the sealing length 72 is a seal of in FIG. 1 achieved low pressure range 38 of a fuel injector. With the reference numeral 60, the inside of the magnetic sleeve 12, that is, the region which is filled by fuel under low pressure, with reference numeral 62, an outer side of the magnet sleeve 12 is designated. A leakage of fuel from the low pressure region 38 to the outside is absolutely to prevent. The contacting pin 28 as shown in FIG Figure 3.2 is symmetrical to the axis 78 of the Kontaktierungspins 28 executed. Reference numeral 74 designates the sealing lips 68 of the sealing element 12 vulcanized into the magnetic sleeve 12 in the deformed state, that is to say in the state applied to the lateral surface 76 of the contacting pin 28.

Figure 4.1 and Figure 4.2 show a variant of the inventively proposed vulcanized sealing element.

That in the Figures 4.1 and 4.2 illustrated in the magnetic sleeve 12 vulcanized sealing element 64 differs from the embodiment according to the Figures 3.1 and 3.2 in that it is designed in a first thickness 80 and a second, reduced thickness 82. In addition, as shown in Figure 4.1 It can be seen that the sealing element 64 vulcanized into the magnet sleeve 12 has a funnel-shaped insertion bevel 84. While the second, reduced thickness 82 is present in the center of the substantially rotationally symmetrical vulcanized sealing element 64, the vulcanized sealing element according to the embodiments in FIG Figures 4.1 and 4.2 formed in the first thickness 80 in the region in which it rests in a diameter jump of the bushing 30 of the magnet sleeve 12. The first thickness 80 exceeds the second, reduced thickness 82 of the vulcanized sealing element 64 by at least two times.

By the insertion bevel 84 on the Kontaktierungspin 28 of the solenoid 22 facing side of the vulcanized in the magnetic sleeve 12 sealing element 64 is guided during assembly of the magnetic coil 22 in the magnetic core 20, the tip of the Kontaktierungspins 28 in the direction of the center of the area in which the second, compared to the first thickness 80 reduced thickness 82 is present. By exerting a small axial force, the tip of the contacting pin 28 penetrates the sealing element 64 vulcanized into the magnetic sleeve 12 in the region of the second, reduced thickness 82 within the insertion bevel 84.

Figure 4.2 shows the assembled state of the Kontaktierungspins.

As a result of the assembly, ie the axial puncturing of the sealing element 64 vulcanized into the magnetic sleeve 12 in the region of the second, reduced thickness 82 and the insertion bevel 84, the sealing lips 68 separated from one another by the tip of the contacting pin 28 or by its lateral surface 26 nestle in the compressed state 74 to the lateral surface 76 of the Kontaktierungspins 28 and form the seal of the low pressure region 38 of a fuel injector. The representation according to Figure 4.2 In addition, it can be seen that the deflection of the sealing lips 68 and their conversion into a compressed state 74 creates a sealing length 72 in the axial direction with respect to the Kontaktierungspins 28, the low pressure region 38 below the armature end face 24 of the magnet group 10 against the outside 62 of the magnetic sleeve 12 effectively seals. By vulcanizing the sealing element 64 whose stationary seat is ensured, wherein the elastic Veronmungseigenschaften the material of the vulcanized sealing element 64 are not affected by this fastening in the shoulder of the bushing 30 in the magnet sleeve 12.

The representation according to Figure 4.2 are the sealing lips 68 in the compressed state 74, ie refer to the outer surface 76 of the Kontaktierungspins 28 along the sealing length 72 deflected state.

The solution described above for sealing contact pins 28 may also be applied to the sealing of other electrical leads, e.g. the supply lines of currently unclaimed piezoelectric actuators or sensors.

Claims (7)

1. Fuel injector having a magnet group (10) comprising a magnet core (20) and a solenoid (22), wherein the magnet group (10) is accommodated in a magnet sheath (12) which has feedthroughs (30) for electrical contact-forming pins (28) of the solenoid (22), wherein elastic sealing elements (64) are vulcanized into the feedthroughs (30) in such a way that in the mounted state a radial prestressing force (70) for forming the seal is applied to the contact-forming pins (28) of the solenoid (22), characterized in that the sealing elements (64) are embodied in a first thickness (80), and in a second reduced thickness (82) in their centre, in that the sealing elements (64) have, in the region of the second, reduced thickness (82), an insertion slope (84) which is penetrated by the contact-forming pins (28) in the magnet sleeve (12) when said contact-forming pins(28) are mounted.
2. Fuel injector according to Claim 1, characterized in that the elastic sealing elements (64) are vulcanized into a shoulder on which a jump in the internal diameter of the feedthroughs (30) is formed.
3. Fuel injector according to Claim 1, characterized in that the elastic sealing elements (64) are of rotationally symmetrical design and have sealing inlets (68) which bear against the lateral surface (76) of the contact-forming pins (28) in the mounted state thereof.
4. Fuel injector according to Claim 3, characterized in that in the state in which they are deflected by the contact-forming pins (28), the sealing lips (68) bear along a sealing length (72) on the lateral surface (76) of the contact-forming pins (28) and seal the feedthrough (30) of the magnet sleeve (12).
5. Fuel injector according to Claim 4, characterized in that the sealing length (72) corresponds substantially to the diameter of the sealing element (64).
6. Fuel injector according to Claim 1, characterized in that the sealing elements (64) bear, when viewed in the penetration direction of the contact-forming pins (28), on a shoulder of the feedthrough (30) in the magnet sleeve (12).
7. Fuel injector according to Claim 1, characterized in that in the mounted state the magnet core (20) in the magnet sleeve (12) is moved into a second angular position (54) and is positioned against radial projections (72) of the magnet sleeve (12) by a spring element (26).

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