EP2193575B1 - Electrical plug connector as a fuel injector contact for vibration-resistant applications - Google Patents

Abstract

An electrical plug connector (1) in the form of a socket contact with a contact inner part (3) for making electrical contact with a pin (2), and with an outer spring (4) which surrounds the contact inner part (3), the contact inner part (3) is, according to the invention, formed from nickel silver.

Description

State of the art

The invention relates to an electrical connector according to the preamble of claim 1.

A conventional connector in the automotive sector, for example, by the DE 94 19 446 U1 known.

From the DE 9419 446 U1 is a connector socket with contact springs for electrically contacting a pin and with a contact springs cross-supporting bushing known. The support sleeve is disposed within a sleeve-shaped central portion of the connector socket, which is integrally connected to the contact springs and thus electrically conductive.

Out DE 102 48 809 A1 is an electrical connector in the form of a vibration-stressed socket contact for producing an electrical connector in the automotive field known. The electrical connector consists of a contact inner part and an over-spring. The inner part itself comprises contact blades, which abut with a contact point on the counterpart, preferably a knife. In order to ensure increased contact reliability by optimal contact normal force at each contact blade even in the case of skewed or oscillating or wobbling counterparts, the inner contact part has at least three groundbreaking contact blades, each of the contact blades has at least one contact point for producing an electrical connector with a knife. In this case, the free ends of the contact blades are based in the manufactured state of an electrical connector on support elements, which are formed as part of the over-spring.

Other versions of electrical connectors are known, for example DE 202 08 635 U1 . EP 0 971 446 A2 and DE 102 24 683 A1 ,

It is known that relative micro-movements that occur due to vibrations of the components (place of attachment) and the wiring harness, between socket contact and knife lead to wear. The classic wear limit for the electrical function is when the coating (surface) is worn through during gilding or when tinning

Tin oxide is formed by fretting corrosion or the tin is rubbed. Classical remedial measures against this contact wear caused by engine vibration or temperature cycling, i. Fretting corrosion in tin-plated systems or abrasion in gold-plated or silver-plated systems are decoupling elements such as a metallic meander or looped copper ribbon, which are effective, but increase the contact cost and usually weaken the current carrying capacity (because of cross-sectional tapering) or in individual cases Increased contact normal force to improve the shaking, with the possible variation of the normal force is limited mostly by the plastic properties (yield point) of the Cu material of the contact springs (lamellae).

In fuel injectors for electrical connection of a control module with a provided in a nozzle module solenoid valve of a magnet assembly, a plug contact with 6-finger contact (see. DE 10 2005 017 424 A1 ) provided in the control module, in which a pin of the nozzle module is inserted. The nickel-plated and gold-plated 6-finger contact is pressed into a socket, which is provided for insulation (ie avoidance of short circuit) with a shrink tube and an insulating sleeve. In the fuel injector, the electrically conductive connection is created starting from connecting bolts in the control module via the 6-finger contact, a solid conductor up to the magnet assembly and back. The contact allows a reproducible mounting and dismounting of the control module and allows the actuation of the magnetic group in the nozzle module for injection. The magnet assembly is fixed in the nozzle module and the socket in the control module. By adding a pressure booster in the fuel injector, the injector extends microscopically (about a few μm), pulling the pin out of the contact area. By injecting the pressure is released and the pin is pushed back into the contact area. Accumulated over the injection cycles and the running time, the plug contact covers a distance of one kilometer. The gold surface of the known plug contact is abraded over the term down to the base material and in the base material. The gold surface has the task to protect the base material from oxidation and, due to its hardness, to reduce wear. The purpose of the nickel layer is to prevent the diffusion of the less noble base material into the gold surface. If there is no gold surface, the risk increases that an oxide layer forms on the base material and the contact point (contact / solid conductor) becomes high-impedance. This can lead to the magnet assembly no longer being energized and therefore no injection possible. Due to the structural design of the fuel injector, the relative movement between solid conductor (pin) and plug contact can not be eliminated.

Disclosure of the invention

Due to the use of nickel silver according to the invention, the service life (wear limit) is not limited by layer penetration (gold, tin, silver) or fretting corrosion, especially since no microcurrents are applied here. German silver is a silver-white shiny alloy of 45-70% copper, 5-30% nickel, 8-45% zinc, possibly with admixtures of trace elements such as lead, tin or iron. It is characterized by special hardness and corrosion resistance because of the nickel content.

Due to mechanical characteristics (yield point, modulus of elasticity) existing disadvantage of a pure nickel silver construction that the achievable normal force is not sufficient to compensate for high abrasion wear by relative / micro-movements, can be resolved by skillful coupling with a spring made of spring steel. The spring steel is very easy to relax, high-strength, rust-free and can cause much greater contact forces than Cu alloys, because the contact forces (normal forces) overlap and for the tolerances of production plus the depth of wear still sufficiently high normal forces can be realized. According to theoretical calculations by means of FEM (finite element method), normal forces (nominal forces) can be set in the range 2 to 16 N, ie approximately one order of magnitude higher than in the case of DE 10 2005 017 424 A1 known plug contact with 1N. Increased insertion forces play no role due to industrial assembly instead of manual assembly with plugs. By virtue of the high normal forces which are possible according to the invention, a compact plug contact construction with a small length and a small diameter is also possible, so that, for example, a pin with a diameter of 1 mm can be contacted. In other words, high contact forces (contact normal forces) are realized in a small space and thus achieves high electrical reliability.

The use of nickel silver as contact material in diesel injectors on solenoid valve basis, the electrical disadvantage (relatively poor conductivity) can be neglected, because usually only very short-term currents below 10 amps, clocked in the range of μs (to ms) occur, which only means very small RMS currents / equivalent currents of less than 1 ampere. Therefore, the disadvantageous conductivity does not lead to thermal overheating and thermal damage. The additional voltage drop in the range of a few mOhm (about 20 mOhm theoretically) is negligible in relation to the voltage drops of the overall system and / or wiring harness, since the length of the inner contact part and the over-spring of the connector according to the invention only a few mm (about 4-9 mm ) is big.

The connector according to the invention offers the possibility of allowing a wear of <0.2 mm per contact area without an oxide layer forming. Since there is no layer, the failure criterion "layer abrasion" is eliminated. By increasing the contact normal force per contact area by a factor of 10, it is possible to reduce the micro-movements and thus reduce the wear. In addition, the quality requirements can be met because with such high normal force extraneous layer thicknesses can be pushed through to keep the electrical contact resistance small and stable. The connector according to the invention can also be used under diesel engine conditions, ie in engine oil, engine oil / water and engine oil / diesel / water environments.

1. a) bauraumneutral, d.h. die Außengeometrie/Einbaumaße sind gleich der bisherigen Konstruktion. Bei einem Wechsel auf die erfindungsgemäße Neusilberkonstruktion bleiben die Bauteile, in denen die Steckbuchse eingebaut/durchgesteckt wird, unverändert. Ein Wechsel kann also rasch und ohne Abstimmung mit anderen Bauteilen erfolgen.
2. b) Die Funktionalitäten sind auf mehrere Bauteile verteilt, nämlich Übertragen des Stroms durch das Kontaktinnenteil, Aufbringen der Kontaktnormalkraft durch die Überfeder (z.B. aus Federstahl, CuBe2 o. ä.) und Lagefixieren durch die Buchse, über die gesamte Lebensdauer, was die Konstruktion robuster macht. Weiterhin kann jedes Bauteil auf seine Aufgabe hin optimiert werden.
3. c) Das Kontaktsystem benötigt keinen Oberflächenschutz aus z.B. Gold oder Silber. Durch den Einsatz von Neusilber wird die Lebensdauer (Verschleißgrenze) nicht durch den Schichtdurchrieb (Gold, Zinn, Silber) oder Reibkorrosion begrenzt.
4. d) Anpresskräfte (Kontaktnormalkraft) je Kontaktstelle sind gegenüber bisher bekannten Steckverbindern um Faktor 10 höher. Folglich treten keine durch zu geringe Anpresskräfte bedingten Stromunterbrechungen auf, und Verschleiß wird durch das Eliminieren von Mikrobewegungen reduziert.
5. e) erhebliches Kosteneinsparpotential, da der im Steckkontakt kontaktierte Pin nicht mehr partiell vergoldet und verzinnt zu werden braucht.
6. f) Einsatz in Motorölumgebung und ungedichtete Konstruktionen sind möglich, bei denen der Kontaktbereich mit Medien, wie z.B. Motoröl etc., bei Temperaturen von -40 °C bis 140 °C benetzt ist.

Further advantages of the connector according to the invention are:

1. a) space neutral, ie the outer geometry / installation dimensions are equal to the previous design. When changing to the nickel silver construction according to the invention, the components in which the socket is installed / pushed through, remain unchanged. A change can be done quickly and without coordination with other components.
2. b) The functionalities are distributed over several components, namely transferring the current through the inner contact part, applying the contact normal force by the over-spring (eg spring steel, CuBe2 o. Ä.) And fixing position through the bush, over the entire life, making the construction more robust power. Furthermore, each component can be optimized for its task.
3. c) The contact system does not require any surface protection such as gold or silver. Due to the use of nickel silver, the service life (wear limit) is not limited by the layer penetration (gold, tin, silver) or fretting corrosion.
4. d) Contact forces (contact normal force) per contact point are 10 times higher than previously known connectors. As a result, no power interruptions due to low contact forces occur, and wear is reduced by eliminating micromotion.
5. e) considerable cost savings potential, since the pin contacted in the plug contact no longer needs to be partially gold plated and tinned.
6. f) Use in engine oil environment and unsealed constructions are possible in which the contact area with media such as engine oil, etc., is wetted at temperatures of -40 ° C to 140 ° C.

Further advantages and advantageous embodiments of the subject invention are the description, the drawings and claims removed.

Short description of the drawing

Fig. 1

ein Ausführungsbeispiel des erfindungsgemäßen elektrischen Steckverbinders; und

Fig. 2

einen Kraftstoffinjektor mit einem Düsenmodul und einem Steuermodul, welches den in Fig. 1 gezeigten Steckverbinder aufweist.

The electrical connector according to the invention is shown in the drawing and explained in more detail in the following description. The features shown in the figures are purely schematic and not to scale. It shows:

Fig. 1

an embodiment of the electrical connector according to the invention; and

Fig. 2

a fuel injector with a nozzle module and a control module, which the in Fig. 1 having shown connector.

Embodiment of the invention

The in Fig. 1 shown electrical connector 1 is designed as a female contact or circular contact and is used for electrically contacting a pin . 2

The electrical connector 1 comprises a contact inner part 3 for electrically contacting the pin 2, a surrounding the inner contact part 3 over spring 4 and a metal bushing 5. The contact inner part 3 is made of nickel silver, preferably N18 (Wieland trade name), and in the illustrated embodiment as a longitudinally slotted round Sleeve formed, which has a plurality of inwardly directed contact fingers (lamellae) 6 and may be formed for example by a rolled-sheet metal part made of nickel silver. The inner contact part 3 thus has no surface coating, in particular no gold, silver or tin coating. The contact inner part 3 is clamped in the over-spring 4, which is made of stainless spring steel (eg 1.4310 with strength 1500 MPA). The over-spring 4 in turn is mounted in the metal bushing 5, for example made of brass and clamped therein, wherein the clamping force is greater than the insertion force of the pin 2. The metal bushing 5 is electrically connected via the over-spring 4 with the contact inner part 3 and in turn attached to the stripped end of an electrical line 7 . The metal bush 5 is surrounded by an insulating sleeve 8 , and the electrical line 7 is covered with a shrink tube 9 .

Due to the sheet thickness or wall thickness, the length of the contact fingers 6 and the width of the longitudinal slots, the contact pressure and the stiffness of the inner contact part 3 can be adjusted. By superposition with the over-spring 4, the normal force of the contact fingers 6 can be massively increased and trimmed in the target area to compensate for both, both manufacturing tolerances and wear due to wear. To form the electrical connector pin 2, for example, a round pin made of nickel silver with 1 mm diameter, in the opening 10 of the metal bushing 5 and inserted between the contact fingers 6 of the contact inner part 3, against the return action of the over-spring. 4

Fig. 2 shows a fuel injector 20 with a nozzle module 21 and a control module 22, which the in Fig. 1 has shown connector 1. The fuel injection is controlled by means of a solenoid valve (not shown) which is part of a magnet assembly 23 of the nozzle module 21. The magnet assembly 23 has a solid conductor 24 which preferably extends to the control module 22 and also has nickel silver, the end of which, embodied as a pin 2, is plugged into the plug connector 1 in the control module 22. The connector 1 offers the possibility of allowing a wear of <0.2 mm per contact area without forming an oxide layer. Since there is no oxide layer, the failure criterion layer abrasion is eliminated. By increasing the contact normal force per contact area by a factor of 10 micro-movements between solid conductor 24 and contact inner part 3 and thus the wear is reduced. In addition, the electrical contact resistance between the solid conductor 24 and the inner contact part 3 is kept small and stable by the high normal force, whereby at temperatures up to 140 ° C and over the life of 24,000 h in the control module 22 neither power interruptions nor high impedance occur.

Claims (8)

1. Electrical plug connector (1) in the form of a socket contact, having a contact inner part (3) for making electrical contact with a pin (2) and having a surrounding spring (4) which surrounds the contact inner part (3), with the surrounding spring (4) being arranged, in particular held in a clamping manner, within a metal bushing (5), and the metal bushing (5) being electrically conductively connected to the contact inner part (3), characterized in that the contact inner part (3) is formed from nickel silver, and in that the contact inner part (3) and the metal bushing (5) are electrically conductively connected to one another by means of the surrounding spring (4) arranged between them.
2. Electrical plug connector according to Claim 1, characterized in that the contact inner part (3) is formed without a surface coating.
3. Electrical plug connector according to Claim 1 or 2, characterized in that the contact inner part (3) is held in a clamping manner within the surrounding spring (4) and is electrically conductively connected to the surrounding spring (4).
4. Electrical plug connector according to one of the preceding claims, characterized in that the metal bushing (5) is in the form of a sleeve.
5. Electrical plug connector according to one of the preceding claims, characterized in that the contact inner part (3) is in the form of a sleeve.
6. Electrical plug connector according to Claim 5, characterized in that the sleeve is slotted and has a plurality of contact fingers (6).
7. Electrical plug connector according to Claim 5 or 6, characterized in that the sleeve is a rolled-up sheet metal part.
8. Fuel injector (20) having at least two modules (21, 22) and having an electrical plug connector (1) according to one of the preceding claims, with the plug connector (1) being provided in one of the two modules (21, 22) and a pin (2) of the other module being inserted into the electrical plug connector (1).

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