DE20106753U1 - Small coupling connector, in particular for a planar broadband lambda probe, in particular with a secondary lock as a control function element - Google Patents

Description

04.04.01 Gf/Hl

Robert Bosch GmbH PO Box 30 02

D-70442 Stuttgart

Small-sized coupling plug, in particular for a planar broadband lambda probe, in particular with a secondary locking mechanism as a control function element

The invention relates to a coupling plug, in particular for a planar lambda probe, comprising a housing, namely a base body and a cover element as well as electrical components that can be inserted into the housing and fixed, and an adjustment element for a probe, in particular a planar broadband lambda probe, which is to be attached in the coupling plug or via a further contact element outside the coupling plug, wherein the cover element can be plugged over the adjustment unit and has a primary lock and a secondary lock that interacts with the cover element, and the secondary lock is provided as a fixing element for fixing at least one electrical contact inserted in the housing and this fixing element has support elements pointing towards the cover element in such a way that the cover element closes completely only in the end position of the secondary element.

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State of the art

Coupling plugs of the above type are generally designed for the connection between a wiring harness plug and a lambda sensor, whereby the connections provided in the coupling plug are intended for calibration, signal and/or heating of the sensor. The lambda sensor and the lambda control in conjunction with the 3-way catalytic converter now represent an effective exhaust gas purification process. The lambda sensor, which is screwed into an exhaust system, for example, includes a sensor for determining the oxygen content in the exhaust gas. 10

The residual oxygen content is a very good measuring parameter and regulates the air-fuel ratio, as it precisely indicates whether the air-fuel mixture is burning completely.

The lambda sensor delivers a voltage signal that represents the current value of the mixture composition and follows the mixture changes. The fuel supply to the engine is regulated by a mixture preparation system according to the signal from the lambda sensor in such a way that a stoichiometric air-fuel ratio λ=1 is achieved.

Depending on the design of the exhaust system and the operating conditions, heated or unheated sensors are used. The lambda sensor also has other applications outside of fuel vehicles, e.g. for controlling gas engines or oil/gas burners.

Broadband lambda sensors in particular have a modular design and, in conjunction with planar technology, allow the integration of several functions. They usually have functional layers consisting of a porous protective layer, an outer electrode, a sensor foil, an inner electrode, a reference air duct foil, an insulation layer, a heating element, a heating foil, a resistor or a calibration element and connection contacts.

Since the broadband lambda probe consists of a combination of a Nernet concentration cell (= sensor cell) with an oxygen ion transporting pump cell, it can measure very precisely not only in the stoichiometric point at &lgr;=1, but also in the lean and rich range.

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Each probe must be calibrated individually. For this purpose, the probe has a built-in resistor ("mini-hybrid"). The calibration, which is preferably carried out using a laser beam, is carried out by removing the resistance layer on a ceramic substrate, which causes a change in resistance and thus calibrates the probe.

One embodiment consists in that the adjustment unit or the resistor is arranged directly on the probe. Another embodiment consists in that the resistor is housed outside, for example on a cable harness connector coupled to the probe.

Up to now, the adjustment has been carried out by transporting the housing of the coupling plug, in which the resistor is installed, to the adjustment point without the cover element. After the appropriate laser processing for the adjustment, the cover element was then attached at another assembly point.

To prevent moisture, dirt or similar from penetrating the coupling plug and to ensure that the appropriate atmosphere prevails inside the coupling plug, the cover element has additional seals. Pressure compensation elements are also arranged on the housing of the coupling plug.

Disadvantages of the state of the art

After the cover element has been fitted, it is possible for both the supplier of the coupling plug and the user to remove the cover element and possibly carry out further adjustment or to manipulate the coupling plug itself.

Since the cover element can be easily clipped onto the base body of the coupling plug, it can be loosened and removed in such a way that it is no longer possible to prove at what point in time the cover element was removed.

There are known securing elements that seal the cover element with the base body, for example adhesive strips, which can be removed

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parabolic tear. However, these can also be easily made yourself. There is also the possibility that the adhesive strip was accidentally destroyed when installing the coupling plug.

Object of the invention

The object of the invention is to further develop an embodiment of the coupling plug, which is intended in particular for a planar broadband lambda sensor, in such a way that it can be produced very cost-effectively and has a control function element by means of which it can be easily determined whether or not the cover element has been removed by third parties without permission.

Solution to the task

The solution to the problem consists in that at least one of the free ends of the support elements has control elements pointing away from the longitudinal extension of the support elements, which are designed such that in a first position of the fixing element, it cannot be moved in the direction of the base body, and in a further position it can be moved from a defined position to an end position.

Advantages of the invention

A significant advantage of the invention is that the coupling plug proposed here according to the invention is designed to be small, since due to the compact design, namely the insertion of electrical contacts in a base body and the arrangement of the adjustment element also in the coupling plug, the external dimensions of the coupling plug, which is preferably arranged between a cable harness and a lambda probe, are very small.

It is also advantageous that the coupling plug according to the invention has only a few components. This enables cost-effective and efficient production.

Since the base body is completely surrounded by the cover element, it is possible to seal the interior of the coupling plug by arranging sealing lips within the cover element or by arranging seals on the base body, so that it is protected in particular against splash water and/or dirt.

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In addition, this also supports the locking of the cover element to the base body. Preferably, a pre-locking and a final locking or a primary and a secondary locking is provided. This is designed in such a way that the cover element has locking arms which, when the cover is closed, rest against the base body of the coupling plug and lock there with locking lugs.

This primary locking takes place in two stages. In a first stage, the cover element locks in such a way that it is held on the base body. By pressing the cover element further in the direction of the base body, the fixing element inserted in the base body is fixed to the electrical contact element guided in the base body, for example a flat plug sleeve that is connected to the lambda probe. However, the fixing only takes place in the form of the fixing element being pressed onto the contact element so that the contact element and the fixing element form a firm connection. In addition, the fixing element is positively guided in the base body, which means that when the contact element is fixed, the fixing element can only move in the axial direction of the cover. In addition, support elements pointing away from the fixing element are provided on the fixing element and extend in the direction of the cover element.

Furthermore, the support element and thus the fixing element have control elements that extend away from the longitudinal extension of the support elements. When functioning properly, these control elements engage behind a hold-down device that is firmly connected to the base body of the coupling plug. This limits the longitudinal movement of the secondary locking device in such a way that the fixing element can only move in the direction of the base body. If the secondary locking device has not been installed correctly, the control elements rest on the hold-down device and the fixing element cannot be moved in the direction of the base body by pressing down the cover element. This makes it possible to immediately determine that the secondary locking device has not yet been installed correctly.

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When the secondary locking mechanism is not activated, i.e. when the contact element is not fixed, the support elements extend so far beyond the base body of the coupling plug that the cover element can only be retained in the first locking position of the primary locking mechanism. The cover element only enters the second locking position of the primary locking mechanism when the contact element is fully activated and thus correctly fixed.

This has the advantage that it is easy to check whether successful contact has been made and thus whether the electrical contact element to the lambda probe has been secured, and that the cover element is tightly sealed against the base body.

Advantageously, suspension devices are provided on the circumference of the cover element, which allow the coupling plug to be attached to another part, for example by means of a tongue and groove connection, or suspension devices such that electrical cables can be attached to the coupling plug.

Optional mounting options for splash guards are available.

A further advantage of the invention is that the aforementioned seals can be molded onto the cover element so that they are arranged in a captive manner.

In order to ensure a constant contact resistance between the adjustment unit and the electrical contact elements, a solder connection is provided.
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Advantageously, the lid element is made of PBT (polybutylene terephthalate) or equivalent materials.

A further advantageous embodiment of the invention is that the cover element is designed to be transparent. This makes it possible for the cover element to be mounted before the adjustment, since with transparent cover elements the adjustment can be carried out using a laser beam through the cover element.

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Further advantageous embodiments emerge from the following descriptions, the claims and the drawings.

Show it:

Fig. 1 A perspective view of the coupling plug according to the invention, with the cover element detached; 10

Fig. 2 is a rear view of the coupling plug according to Fig. 1;

Fig. 3 is a plan view of the coupling plug according to Fig. 2;

Fig. 4 is a perspective view of the coupling plug according to Fig. 1, but in section compared to Fig. 1 and with the cover fitted and mounted;

Fig. 5 is a section through the wiring harness connector according to Fig. 1 with the cover element in the pre-locking position;

Fig. 6 a section through the cable harness connector according to Fig. 1 with the cover element immediately before the end position;

Fig. 7 is a section through the wiring harness connector according to Fig. 1 with the connector in the end position;

Fig. 8 is a simplified representation of the secondary locking element

ments in an incorrectly assembled manner; 30

Fig. 9 is a simplified representation of the secondary locking element in a functional position.

Description of an embodiment

The coupling plug 1 shown in Fig. 1 to 4 is such a plug, which consists of a housing 2 that is composed of a base body 3 and a cover element 4.

A calibration unit 6 is arranged on the base body 3 in a holding device 5, which in turn is connected via electrical contact elements 7 to the lambda probe connected via a connecting element 8 or to the plug inserted into the coupling plug 1 and not shown in more detail in the drawings.

The electrical contact elements 7 consist of metal strips shaped like conductor tracks, one side of which ends in the area of the coupling option 9 (Fig. 4) of the coupling plug 1.

The adjustment unit 6 is guided via guide elements 10, which are mostly arranged on the base body 3, and is held in the correct position by the electrical contact elements 7.

In order to prevent the lateral displacement of the adjustment unit 6, support elements 11 are provided perpendicular to the longitudinal extension of the adjustment unit 6. These support elements 11, as shown in particular in Figs. 5, 6 and 7, are designed as part of a fixing element 12.

The fixing element 12 is provided as a secondary locking element and has the function of holding an electrical contact 13 arranged in the housing 2, which is connected in particular to the lambda probe, in the correct position.

For this purpose, the fixing element 12 is preferably W-shaped in its cross section, wherein it encloses the electrical contact 13 axially between its two legs 12a/12b in the assembled state (Fig. 7).

The secondary locking element or the fixing element 12 is further designed such that it preferably forms an integral part with the support elements.
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In the not yet mounted and fixed state of the electrical contact 13, as shown in Fig. 5, the support elements 11 protrude in such a way

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far out of the housing 2 that the cover element 4, which is placed on the housing 2, can only be fixed in a pre-locking position.

This means that if the secondary locking mechanism is not actuated and the electrical contact 13 is not fixed properly and the fixing element 12 is not positioned correctly, the cover element 4 does not close (see Fig. 6).

Only by correctly positioning the secondary locking mechanism in its end position is it possible for the cover element 4 to assume its own end position.

Once the secondary locking mechanism has been installed, it can no longer be released without completely destroying the coupling plug 1.

In order to prevent the inserted fixing element 12 (secondary locking) from coming out unexpectedly, control elements 20 are arranged on the free ends of the respective legs 12a, 12b, which in the embodiment shown in Fig. 9 and 10 protrude perpendicularly from this and form nose-like bulges. These control elements 20 engage in a hold-down device 21 which is directly connected to the housing 2 of the coupling plug 1. The hold-down device 21 has a recess 22 into which the control element 20 of the fixing element 12 engages, provided that the secondary locking is installed correctly. If the fixing element 12 is not installed correctly, the control elements 20 rest on the hold-down devices 21, so that the cover element 4 cannot be fixed on the base body 3 of the coupling plug 1.

Preferably, the coupling plug 1 has grooves 14 on its circumference, which allow a coupling plug 1 to be inserted into holders provided for it.

In addition, holding and fixing elements 15, as shown in Fig. 2, are arranged in the base body 2, which allow the coupling plug 1 to be arranged on electrical lines 16, as shown in Fig. 1.

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For this purpose, the holding element 15 is designed as a clip so that the coupling plug 1 can be plugged onto a cable harness when the holding element 15 is in the open position and can then be closed by means of a further movement.

This provides the opportunity to attach the coupling plug to a motor (holder), for example.

Due to its small external mass, it is also possible to accommodate the coupling plug in a grooved tube.

Claims (3)

1. Coupling plug ( 1 ), in particular for a planar lambda probe, consisting of - a housing ( 2 ), namely a base body ( 3 ) and a cover element ( 4 ) and - electrical components that can be inserted and fixed into the housing, and - a calibration element ( 6 ) for a probe, in particular a planar broadband lambda probe, which is to be mounted in the coupling plug ( 1 ) or via a further contact element outside the coupling plug, wherein - the cover element ( 4 ) can be plugged over the adjustment unit ( 6 ) and has a primary lock and a secondary lock that interacts with the cover element ( 4 ), and the secondary lock is provided as a fixing element ( 12 ) for fixing at least one electrical contact ( 13 ) inserted in the housing ( 2 ) and this fixing element ( 12 ) has support elements ( 11 ) pointing towards the cover element ( 4 ) in such a way that the cover element ( 4 ) closes completely only in the end position of the secondary lock, characterized in that
at least one of the free ends of the support elements ( 11 ) has control elements ( 20 ) pointing away from the longitudinal extension of the support elements ( 11 ), which are designed such that in a first position of the fixing element ( 12 ) it cannot be moved in the direction of the base body ( 3 ), and in a further position it can be moved from a defined position into an end position. 2. Coupling plug according to claim 1, characterized in that the support element ( 11 ) has a nose-like formation which engages behind a recess ( 22 ). 3. Coupling plug according to at least one of the preceding claims, characterized in that the recess ( 22 ) is formed in a hold-down device ( 21 ) connected to the housing ( 2 ).