DE102011115786A1 - Method of manufacturing belt buckle-switch for belt buckle, involves providing electrically conductive lead frame element which comprises molding region and contact region - Google Patents

Abstract

The method involves providing an electrically conductive lead frame element (10) which comprises a molding region and a contact region. The lead frame element is molded with a plastics material such that the molding region is surrounded by the plastic material and the contact region protrudes opposite to the plastics material. The lead frame element is provided such that the contact region has two contact tongues (18,20). The contact tongues are attached with each other for setting a switching state and are separated from each other for setting another switching state.

Description

The present invention relates to a method for manufacturing a buckle switch for a buckle.

Such a buckle is well known and is used in particular in motor vehicles. In motor vehicles, in most countries a seat belt is mandatory, and many vehicle manufacturers at least want to remind the driver whether or not he has put on his safety belt.

By sensor means can be detected whether the belt tongue is locked, so if the seat belt is applied. A signal output by the sensor means can be used in a higher-level control device to control suitable displays (acoustically and / or optically). In particular, the sensor means of the buckle can be coupled with sensors in the vehicle seats, which determine whether the respective seat is occupied or not. If a person is detected on a motor vehicle seat and the associated seat belt is not applied, as a seat-belt reminder z. B. a flashing light in an instrument cluster of the vehicle and / or an audible warning tone activated.

In known buckles, the sensor means either microswitches or Hall sensors, which detect whether the belt tongue is locked or not. If a Hall sensor is used, it is detected inductively whether the belt tongue has been inserted sufficiently far into the opening of the belt buckle. If this is the case, it can be assumed that the belt tongue is locked. When using a microswitch, this position is detected by operating the microswitch. It is conceivable that the belt tongue actuates the microswitch directly. Similarly, it is known that a mechanical actuator is provided which transmits a force exerted on the belt tongue during insertion of the belt tongue force on the microswitch.

The publication DE 202 04 318 U1 describes a detection device for a buckle of restraint systems of motor vehicles for indicating whether the belt tongue is inserted into the buckle and properly locked. The detection device has a fixed contact plate and a contact spring, which is pressed by a pressed by a belt tongue slide against the fixed contact plate.

In the DE 199 07 716 A1 a Hall sensor is shown in which a Hall detector and a permanent magnet are used to detect whether the belt tongue is in the buckle.

However, both prior art Hall sensors and microswitches are relatively expensive components. In the known micro-switches, the durability is also a critical point due to the many mechanical moving parts.

Against the above background, it is the object of the present invention to provide an improved, in particular more cost-effective method for producing a buckle switch, which has a higher durability.

The above object is achieved by a method for producing a belt buckle switch for a buckle, wherein initially an electrically conductive punched grid element is provided which has an encapsulation region and a contact region, wherein the stamped grid element is encapsulated with a plastic material such that the encapsulation area is surrounded by the plastic material and that the contact area protrudes with respect to the plastic material, and wherein the stamped grid element is provided such that the contact area has a first and a second contact tongue which can be applied to each other for setting up a first switching state and for setting up a second switching state are separable from each other.

Further, the above object is achieved by a buckle switch for a vehicle seat belt buckle, wherein the buckle switch is made according to the method of the above-mentioned type.

Due to the fact that the production method according to the invention only involves providing the electrically conductive stamped grid element and encapsulating the stamped grid element with the plastic material, the production of the buckle switch can be made very simple. Due to the few production steps, the production is very cost-effective.

Since the buckle switch according to the invention has only the electrically conductive stamped grid element and the plastic material encapsulated around the stamped grid element, only a few individual elements are required for the production of the buckle switch. Furthermore, the buckle switch is a single component that can be easily mounted in a buckle. This leads to a high degree of robustness of the switch and the belt buckle thus equipped and, accordingly, to a low susceptibility to interference.

Due to the few mechanically moving parts also the durability of the buckle switch is increased.

In the present case, the protrusion of the contact region with respect to the plastic material is understood to mean that the contact region of the stamped grid element can also be accessed after the encapsulation process, in order, for. B. to allow the electrical contact of the reeds and / or to produce an electrical coupling with external components. In contrast, the encapsulation area of the stamped grid element is surrounded by the plastic material and thus insulated.

This completes the task.

It is particularly advantageous if the stamped grid element is provided such that the first and the second contact tongue rest elastically against each other for establishing the first switching state.

By the elastically abutting contact tongues is achieved that the first switching state is automatically set up again after leaving a second switching state.

According to a further embodiment, the first and / or the second contact tongue is formed in the region of its free end such that a switching slide for changing the switching state can attack it.

When inserting the belt tongues in the buckle, the slide switch is pushed between the first and the second contact tongue. Thus, the first and second contact tongues are electrically separated from each other.

It is advantageous if the two elastically abutting contact tongues together form a conical insertion section for the slide switch.

By the conical insertion section, a safe and controlled insertion of the slide switch between the first and the second contact tongue can be ensured.

In a further preferred embodiment of the method, the stamped grid element is provided in such a way that a first stamped grid section, which has the first contact tongue, and a second stamped grid section, which has the second contact tongue, are connected to one another via at least one stamped grid web , and wherein at least one leadframe web is removed after encapsulation of the stamped grid element.

By providing a stamped grid element which has a plurality of electrically conductive stamped grid sections and at least one stamped grid web connecting them, the arrangement of the stamped grid sections can be exactly fixed during the overmoulding. This achieves high manufacturing precision.

As a result of the encapsulation process, the stamped grid sections, which can also be bent several times, are stabilized before further processing.

In addition, since the encapsulation process takes place as long as the at least one leadframe web is still present, it is ensured that the stamped grid sections do not dodge or touch each other during the encapsulation process. Thus, a good insulation of the various punched grid sections is guaranteed against each other. Thereafter, the buckle switch produced by the present method has increased vibration safety.

In a further embodiment, the stamped grid element is punched out of a flat piece of sheet metal and then bent.

This procedure makes it possible to initially prepare the stamped grid elements in a simple process step. In a second step, the first and the second contact tongue of the stamped grid element are then provided by a bending process.

In this case, it is advantageous if at least one of the two contact tongues is produced by bending, being bent relative to a plane of the sheet about a first bending axis and about a second bending axis, the first and the second bending axis being skewed relative to one another.

By this bending process, a design of the contact tongues is provided, which has a good elasticity and at the same time a good durability.

According to another preferred embodiment, one of the contact tongues is provided so that it is forked in a contact section.

In this way, a kind of redundancy can be achieved because an electrical contact is already made when one of the two forks comes into contact with a mating contact of the other contact tongue.

Furthermore, the mating contact, in particular in the contact portion with the fork tines, be made wider to further increase the safety and reliability of the switching behavior of the buckle switch.

It is understood that the abovementioned and those still to be explained below Characteristics can be used not only in the specified combination, but also in other combinations or in isolation, without departing from the scope of the present invention.

Embodiments of the invention are illustrated in more detail in the drawing and are explained in more detail in the following description. Show it:

1 a schematic plan view of a stamped grid element made of an electrically conductive material;

2 one of the 1 corresponding plan view of a buckle switch, made by molding the stamped grid element;

3 a schematic representation of a buckle with the buckle switch according to the invention;

4 a detailed view of a contact tongue of the buckle switch in a contact area;

5 an electrical equivalent circuit diagram of the buckle switch in a first embodiment; and

6 an electrical equivalent circuit diagram of the buckle switch in a second embodiment.

In 1 is in schematic form a stamped grid element 10 shown, which is made of an electrically conductive material, for example. Made of copper.

The punched grid element 10 has a first punched grid section 12 and a second punched grid section 14 on, by means of several stamped webs 16a . 16b . 16c connected to each other. Furthermore, the stamped grid sections 12 . 14 about electrical components 17a . 17b be coupled.

The first punched grid section 12 , the second punched grid section 14 and the punched metal bars 16 form a one-piece, rigid lattice component.

The first punched grid section 12 has a first contact tongue 18 and the second punched grid section 14 a second contact tongue 20 on.

The punched grid element 10 is an output component for a manufacturing method according to the invention for producing a belt buckle switch 21 for a buckle 22 , A schematic illustration of the buckle 22 is the 3 refer to. The buckle 22 also has a slide switch 23 on when inserting a belt tongue 24 against the buckle switch 21 is pressed.

In a first step of the manufacturing process, the stamped grid element 10 initially punched out of a plane electrically conductive material.

Subsequently, the two contact tongues 18 . 20 provided by bending. These are the two contact tongues 18 . 20 in a first step with respect to a plane through the hitherto flat punched grid element 10 is formed to first bending axes 26a . 26b bent. This causes the two contact tongues 18 . 20 out of the plane. In a second step, the two contact tongues 18 . 20 around second bending axes 28a . 28b bent perpendicular to the plane defined above. In an embodiment, not shown, the second bending axes 28a . 28b at any angle to the plane. From the 1 it can be seen that the first and the second bending axes 26a . 26b . 28a . 28b crooked to each other.

By this bending process, the first contact tongue 18 and the second contact tongue 20 provided so that they lie against each other elastically. This forms a first switching state of the buckle switch 21 ,

When inserting the belt tongue 24 in the buckle 22 that the buckle switch of the invention 21 has, a force on the slide switch 23 exercised as a result, between the first contact tongue 18 and the second contact tongue 20 is pushed. This in turn leads to a change in the switching state of the buckle switch 21 ,

When removing the belt tongue 24 from the buckle 22 , is the slide switch 23 withdrawn again. Because of this, the contact between the first contact tongue closes again 18 and the second contact tongue 20 , This restores the first switching state.

Out 1 It can be seen that the two elastically abutting contact tongues 18 . 20 a conical insertion section 32 exhibit. This form of introduction section 32 facilitates the insertion of the slide switch 23 between the first contact tongue 18 and the second contact tongue 20 , Furthermore, the reliability of the buckle switch 21 elevated.

How out 4 to see is the first contact tongue 18 so provided that they are in a contact section 34 forked. The second contact tongue 20 is at least in the area of the contact section 34 wider. By this redundancy measure, the reliability of the buckle switch 21 elevated.

The shape of the reeds 18 . 20 in the area of the contact section 34 allows easy rolling of the reeds 18 . 20 up to today. This leads to a lower friction during insertion of the slide switch 23 between the two contact tongues 18 . 20 , Due to this results in a higher durability of the buckle switch 21 ,

In an alternative, not shown embodiment of the manufacturing process, the two contact tongues 18 . 20 be provided so as to be spaced apart in the first switching state and thus electrically separated. Will the belt tongue 24 in the buckle 22 introduced, then the slide switch 23 against the buckle switch 21 pressed. As a result, the two tongues become 18 . 20 pressed against each other and thus electrically connected. This forms the second switching state.

2 shows one of the 1 corresponding top view of the buckle switch 21 by overmolding the stamped grid element 10 will be produced.

The punched grid element 10 has a Umspritzungsbereich 42 and a contact area 44 on. The encapsulation of the stamped grid element 10 with a plastic material is carried out so that the coating area 42 surrounded by the plastic material, whereas the contact area 44 protruding from the plastic material and thus is available for electrical coupling. In this case, the contact area 44a . 44b the first and the second contact tongue 18 . 20 on. The contact area 44c . 44e can about the electrical components 17a . 17b with the contact area 44d . 44f be connected. The contact area 44g . 44h is used for connection of electrical wiring 46a . 46b used. These can be z. B. by means of a soldering operation with the contact area 44g . 44h be electrically connected. The coating area 42a has a bridge portion, in particular the contact area 44a . 44b mechanically stabilized to ensure the durability of the buckle switch 21 to increase. The coating area 42b serves to accommodate and fix the electrical cables 46a . 46b and thus relieves the electrical connections between the electrical lines 46a . 46b and the contact area 44g . 44h of mechanical tensile forces. Finally, the buckle switch 21 with the help of the encapsulation area 42c . 42d with other components, eg. B. the housing of the buckle 22 , be mechanically connected. Through the extrusion process, the first punched grid section 12 and the second punched grid section 14 stabilized. Since the encapsulation process takes place as long as the leadframe webs 16 are still present, it is ensured that the two punched grid sections 12 . 14 during the Umspritzvorgangs not dodge or can touch.

After fixing the two punched grid sections 12 . 14 by the extrusion process, now at least one of the leadframe webs 16 be removed. This is done by punching or by drilling or lasers.

5 shows an electrical equivalent circuit diagram of the buckle switch 21 in a first embodiment. The contact area 44g is with the contact area 44h only over the two reeds 18 . 20 electrically coupled. This is achieved by punching out the leadframe webs 16a and or 16c , The punched grid bridge 16b remains. The electrical components 17a . 17b are not present in this embodiment.

By punching out the above stamped webs 16 be the two punched grid sections 12 . 14 exclusively via the two contact tongues 18 . 20 electrically connected to each other. This step introduces the functionality of the buckle switch 21 produced. In the first switching state, in which the first and the second contact tongue 18 . 20 abutting each other elastically, are the two punched grid sections 12 . 14 electrically connected to each other. Then the slide switch 23 between the two contact tongues 18 . 20 introduced, so are the two stamped grid sections 12 . 14 electrically isolated from each other. Thus, it can be detected whether the belt tongue 24 in the buckle 22 was introduced.

6 shows another electrical equivalent circuit diagram of the buckle switch 21 in a second embodiment. The contact area 44g is with the contact area 44h over the electrical component 17a , in the present case the resistance 17a , and a series connected parallel circuit of the reeds 18 . 20 and the electrical component 17b , in the present example the resistance 17b , electrically connected. These are the punched grid webs 16b and 16c punched out. The punched grid bridge 16a remains. The contact area 44c is with the contact area 44d about the resistance 17a electrically connected. In the same way, the contact area 44e with the contact area 44f about the resistance 17b electrically connected.

In the first switching state, in which the first and the second contact tongue 18 . 20 elastic abutting each other becomes the electrical resistance of the buckle switch 21 essentially by the resistance 17a educated. Will now the slide switch 23 between the two contact tongues 18 . 20 introduced, so are the reeds 18 . 20 in the contact section 34 separated from each other. The resistance of the buckle switch 21 thus calculated from the electrical resistors connected in series 17a and 17b , Thus, the resistance of the buckle switch increases 21 in the second switching state. About the resistance can be detected with it, whether the belt tongue 24 in the buckle 22 was introduced.

Thus, while preferred embodiments of the inventive manufacturing method have been shown, it will be understood that various modifications and changes can be made.

For example, the stamped grid element 10 have more than two stamped grid sections. Furthermore, it is possible that the stamped grid sections 12 . 14 over only one leadframe web 16 are connected. Likewise, the bending axes 26a . 26b . 28a . 28b for providing the first and second contact tongues 18 . 20 be changed arbitrarily. For producing the corresponding electrical connections with other components, further elements can be connected to the contact area 44 be soldered. Also, connections can be made to the contact area 44 be soldered.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 20204318 U1 [0005]
• DE 19907716 A1 [0006]

Claims (9)

Method for producing a belt buckle switch ( 21 ) for a buckle ( 22 ), comprising the steps of: providing an electrically conductive stamped grid element ( 10 ), which is an encapsulation area ( 42 ) and a contact area ( 44 ), and - overmolding the stamped grid element ( 10 ) with a plastic material such that the encapsulation area ( 42 ) is surrounded by the plastic material and that the contact area ( 44 ) protrudes opposite the plastic material, wherein the stamped grid element ( 10 ) is provided such that the contact area ( 44 ) a first and a second contact tongue ( 18 . 20 ), which can be applied to each other for establishing a first switching state and which are separable from each other for establishing a second switching state. Method according to claim 1, wherein the stamped grid element ( 10 ) is provided such that the first and the second contact tongue ( 18 . 20 ) to set up the first switching state elastically abut each other. Method according to one of claims 1 to 2, wherein the first and / or the second contact tongue ( 18 . 20 ) is formed in the region of its free end such that a slide switch ( 23 ) can attack it to change the switching state. Method according to claim 2 and 3, wherein the two elastically abutting contact tongues ( 18 . 20 ) together a conical insertion section ( 32 ) for the slide switch ( 23 ) form. Method according to one of claims 1-4, wherein the stamped grid element ( 10 ) is provided such that a first punched grid section ( 12 ), the first contact tongue ( 18 ), and a second punched grid section (FIG. 14 ), the second contact tongue ( 20 ), via at least one leadframe web ( 16 ) are connected to each other, and wherein after the encapsulation of the stamped grid element ( 10 ) at least one leadframe web ( 16 ) Will get removed. Method according to one of claims 1-4, wherein the stamped grid element ( 10 ) is punched out of a flat piece of sheet metal and then bent. Method according to one of claims 1 to 6, wherein at least one of the two contact tongues ( 18 . 20 ) is produced by bending, with respect to a sheet plane around a first bending axis ( 26a . 26b ) and a second bending axis ( 28a . 28b ), wherein the first and the second bending axis ( 26a . 26b . 28a . 28b ) Windschief each other. Method according to one of claims 1-7, wherein one of the contact tongues ( 18 . 20 ) is provided in a contact section ( 34 ) is forked. Buckle switch ( 21 ) for a vehicle seat belt buckle ( 22 ), with the buckle switch ( 21 ) according to the method of any of claims 1-8.

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