DE10156652A1 - Airbag device for vehicle, especially motor vehicle, controls delivered gas quantity in response to signal from sensor detecting airbag displacement with crossing detection strips. - Google Patents

Abstract

The device has an airbag that can be inflated with gas from a filling device and at least one sensor element on the passenger side of the airbag that responds to local pressure changes and sends pressure change signals to a controller that controls the filling device. The delivered gas quantity is controllable in response to a signal from a sensor detecting airbag displacement with mutually crossing pressure change detection sensor strips (1,2). AN Independent claim is also included for the following: a sensor for time and/or position resolving force or pressure measurement.

Description

The invention relates to a sensor for location and / or time-resolved force or Pressure measurement, which has resistance elements, which have a matrix-like grid Rows and columns of spaced apart contact areas of the Form resistance elements, with an electrical resistance on one Contact area of two resistance elements from the force or pressure load of the Contact area is dependent.

Such a sensor is known from DE 198 26 484. The known sensor exists from a matrix-like grid of conductive embedded in a tissue Rows and columns fibers fibers, the line fibers and the column fibers to Contact points, which at the intersection of the row and column fibers are formed, are arranged loosely one above the other. The row fibers and the slit fibers are made of carbon fiber or an elastic fiber semiconducting polymer formed. The ends of the column and row fibers are over electrical connection cable connected to evaluation electronics. The fibers are elastic and have a high flexural and camber-changing flexibility to adapt to a To be able to adjust the deformation of the tissue. The material of the column and Row fibers are chosen such that a contact resistance between a column fiber and a line fiber of the pressurization of the contact point depends. Becomes such a pressurized contact point, the contact resistance is reduced between the row fiber and column fiber concerned. This change in resistance is detected by the connected evaluation electronics, causing pressure changes can be measured in a spatially resolved and / or time-resolved manner at the contact points.

In the known sensor, the column and row fibers are each at their ends contacted with connecting cables, via which the sensor with the evaluation electronics connected is. The elastic carbon fibers used as column or row fibers or polymer fibers simultaneously form the electrical connection between the electrical connecting cables and the contact point at which the measured Resistance change takes place. Have elastic carbon fibers or polymer fibers a higher specific resistance than metallic supply lines, as is usually the case in a resistance measurement as electrical connections between measuring devices and the place where you want to measure. The resulting Measurement errors are small and the measurement accuracy in most applications completely adequate. However, it may be necessary to use the sensor for measurements use where an increased measuring accuracy is required, which in Use of carbon or polymer fibers as electrical connections between the Connecting cables to the evaluation electronics and the contact point is not reached. The use of highly conductive metal fibers as column and row fibers prohibitive doing so for the reason that when the sensor deforms like it for example when the sensor is used in an airbag for motor vehicles may easily break or tear can and are therefore susceptible to interference and moreover, easily oxidized, whereby an oxidation at a contact point, the measurement result falsified.

It is therefore an object of the invention to provide a sensor of the type mentioned at the outset to further develop that a higher measuring accuracy is given.

The object is achieved in that at least one of the Resistance elements at least on one of the contact areas by one on this Contact area with the resistance element in electrical contact electrically conductive element can be subjected to voltage.

The measures according to the invention advantageously achieve that the derivative of the signal indicating a change in resistance from the Junction area of two resistance elements to form an electrical connection line not via the resistance elements themselves, but via the low-resistance element electrically conductive element. This leads to increased measuring accuracy, even if the Resistance elements made of a flexible and stretchable elastic material which is electrically conductive, but is relatively high-resistance.

It can now be provided for a separate pair of for each contact area To provide resistance elements. However, preferably Resistance elements in strips and arranged in rows and columns. Thereby the contact areas of a row or the contact areas of a column formed by the same resistance element arranged in this row or column. This has the advantage that the manufacture of the sensor according to the invention is simplified becomes. It is then no longer necessary to individually lay each contact area on top of one another of separate resistance elements, but the contact areas in a simple way by crossing areas of rows and columns arranged strip-shaped resistance elements formed, whereby the Manufacturing effort of the sensor according to the invention is reduced.

It is preferably provided that the electrically conductive element is strip-shaped and is arranged along a row or column of the contact areas. This makes everyone Contact area of a row or column through an electrically conductive element tension-. It is no longer necessary to contact each individual contact area individually electrically conductive element can be contacted, so that the manufacturing cost of sensor according to the invention is reduced. Contacting is particularly easy achieved when the strip-shaped electrically conductive element along a strip-shaped resistance element is arranged in contact with this. Here is the relevant resistance element at least over part of its length and thus also each one located in this part of the length of the resistance element Contact area contacted by the electrically conductive element. This results in a further reduction of the manufacturing effort of the sensor according to the invention.

Another advantageous development of the invention provides that the electrical conductive element is an electrically conductive fiber embedded in a resistance element is. By embedding in the resistance element is particularly reliable Art achieved that the relevant resistance element with that designed as a fiber electrically conductive element is in electrical contact and the contact area or the Contact areas of the resistance element can be subjected to voltage. It is particularly advantageous if the resistance elements are strip-shaped are formed and the electrically conductive fiber over at least part of the Length, preferably over the entire length of at least one of the Resistance elements extends. This will cover the entire part of the length of the Resistance elements and therefore all those in this part of the length Contact areas contacted by the fiber and applied voltage. It is furthermore advantageous if the electrically conductive fiber in the resistance element meandering. This is achieved in an advantageous manner that at an elongation of the resistance element, as is the case with a Pressurization can occur, only the meander of the fiber apart without that the latter is subjected to tensile forces and can tear off is pulled.

It can be provided that at least part of the contact areas between two resistance elements an element made of a poorly conductive material is arranged. This increases the electrical resistance between the two Resistance elements at their contact portion so that a pressurizing the Contact area causes a larger absolute change in resistance than if the Resistance elements at this contact area would be in direct contact. from that this results in an increased measuring accuracy of the sensor. This becomes particularly effective Resistance increase is achieved when the element made of poorly conductive material covers the entire area of the relevant contact area. This prevents that the two resistance elements in contact at this contact area can come.

It can be provided that the element or elements made of poorly conductive Material is or are strip-shaped and along one or more strip-shaped resistance elements is or are arranged. This will several, preferably all, contact areas of the relevant resistance elements provided by a single continuous element made of poorly conductive material, so that not every contact area is individually provided with such an element got to. This results in a reduction in the manufacturing costs of the sensor according to the invention.

It can be provided that between those arranged in rows Resistance elements and the resistance elements arranged in columns one Layer is arranged which isolating column and row areas as well these column and row areas have delimited, poorly conductive areas, which are arranged in a checkerboard pattern and which are in the contact areas the resistance elements are arranged between them. This will in advantageously achieved that by using a single component, namely the layer having the poorly conductive elements, between the Resistance elements on a large number, preferably on all intersection areas, an element made of a poorly conductive material is arranged, this Elements made of a poorly conductive material are electrically insulated from one another. This results in a further reduction in the production costs of the sensor according to the invention.

An advantageous development of the invention provides that the matrix-like grid in a tissue is arranged, and that electrodes are attached to this tissue, which are arranged in rows and columns, and which in turn are electrical Contact conductive elements. The integration in a tissue ensures that the sensor can be easily installed at its place of use. Preferably there is provided that the sensor is already integrated in a component on which one Pressurization should be measured. The arrangement of electrodes in the Tissue contacting the electrically conductive elements causes any cracks that occur in the electrically conductive elements cause these cracks the electrodes are bridged, making an even more reliable Voltage applied to the contact areas on the resistance elements reached becomes.

It can be provided that several, preferably all in columns and / or several, preferably all resistance elements arranged in rows into a flat one Arrangement are integrated and by electrically insulating areas from each other are separated. This simplifies the manufacturing process for the sensor according to the invention, since then no longer each resistance element individually the sensor must be installed, but several, preferably all Resistance elements are integrated in a single component and in the manufacture of the Sensor only this one component must be installed in the sensor.

Further details of the invention can be found in the two exemplary embodiments remove, which are described below with reference to the figures. Show it:

Fig. 1 shows a section through an inventive sensor according to a first embodiment,

Fig. 2 is a plan view 1 of a first part of the sensor of FIG. In direction II, partly in section,

Fig. 3 is a plan view 1 of a second part of the sensor of FIG. In direction III, partly in section,

Fig. 4 is a schematic representation of a sensor according to a second embodiment,

Fig. 5 is a plan view of a sheet-like element, and

Fig. 6 is a plan view of a flat arrangement of resistance elements.

Figs. 1 to 3 show a first embodiment of a sensor according to the invention. The sensor has strip-shaped resistance elements 5 arranged in rows and strip-shaped resistance elements 15 arranged in columns, which overlap one another in such a way that they form a matrix-like grid of contact areas K. At the contact areas K, between the resistance elements 5 arranged in rows and the resistance elements 15 arranged in columns, an element 6 made of a poorly conductive material is arranged, which covers the entire contact area K concerned. In the exemplary embodiment shown here, the elements 6 made of poorly conductive material are also strip-shaped and run along the strip-shaped resistor elements 15 arranged in columns.

Stripe-shaped electrically conductive elements 4 , 14 made of a highly conductive material, in the exemplary embodiment shown here made of metal, are arranged along the resistance elements 5 , 15 and in contact therewith, so that the resistance elements 5 , 15 are arranged over these electrically conductive elements 4 , 14 and thus also the contact areas K on the resistance elements 5 , 15 can be subjected to voltage. The sensor shown here is, but not absolutely necessary, integrated into a fabric which has cover layers 1 , 11 to which the sensor is attached by means of adhesive layers 2 , 12 . The sensor also has electrodes 3 , 13 which are made of metal and which run along the strip-shaped electrically conductive elements 4 , 14 and are in contact with them. The electrically conductive elements 4 , 14 , or alternatively the electrodes 3 , 13 can be connected to an evaluation device via connecting lines (not shown here). The tissue is held together by seams 7 , which at the same time separate the columns which have the electrodes 13 arranged in columns, the electrically conductive elements 14 arranged in columns and the resistance elements 15 arranged in columns and the elements 6 made of poorly conductive material.

The measuring principle of the sensor, which corresponds essentially to the measuring principle of the sensor known from DE 198 26 484, is now based on the fact that in the contact areas K, the resistance elements 5 , 15 and the element 6 arranged between them are essentially only loose from a poorly conductive material are in contact with each other. When pressure or force is applied to the relevant contact area K, the resistance element 5 of the row, the element 6 and the resistance element 15 of the column are pressed together. This causes a decrease in the electrical resistance between the resistance element 5 of the row and the resistance element 15 of the column at their contact area K. The magnitude of the pressure or force applied to the contact area K can thus be determined by measuring the resistance. When voltage is applied to the contact area K, the measurement signal of the resistance measurement is the current flowing through the contact area K from the resistance element 5 of the row to the resistance element 15 of the column.

The direct application of voltage to the contact areas K by the metal strips 4 , 14 has the additional significant advantage over the sensor known from DE 198 86 484 that an electrical measurement signal, in this case the current characterizing the resistance through the contact area K, does not have the relative high-resistance elements 5 , 15 itself must be derived, but via the low-resistance metal strips 4 , 14 in contact with the contact area K. The resistance elements 5 , 15 thus only, in cooperation with the poorly conductive elements 6 located between them, form electrical resistances at the contact areas K, which can be changed by applying force or pressure and are therefore suitable for applying force or pressure to the contact areas K. to characterize. The contact areas K can thus be connected directly to the evaluation device via the metal strips 4 , 14 and further connecting lines (not shown here).

The metal strips 4 , 14 are not fixed over the entire surface of the strip-shaped resistance elements 5 , 15 , but lie loosely against them or are only fixed at certain points to prevent damage to the metal strips 4 , 14 if the resistance elements 5 , 15 result Pressurization can be stretched. In the event of damage to a metal strip 4 , 14, for example due to cracks, such damage is electrically bridged by the electrodes 3 , 13 . The electrodes 3 , 13 thus increase the reliability of the sensor, but are not absolutely necessary. In the exemplary embodiment shown here, the metal strips 4 , 14 are in contact with the row or column conductor tracks 5 , 15 essentially over their entire length. However, it can also be provided that the electrically conductive elements 4 , 14 are designed and arranged such that they only contact selected contact areas K.

In the exemplary embodiment shown here, it is provided that the resistance elements 5 , 15 are separated at each contact region K by a poorly conductive element 6 . However, it is also possible to provide elements 6 only at individual contact areas K or to omit them entirely. The measuring principle remains the same, however, in the case of direct contact between two resistance elements 5 , 15 , the electrical resistance in the contact area K is significantly smaller, so that when pressure is applied, only a much smaller absolute change in resistance can be measured. Furthermore, it can be provided that the elements 6 are not designed in the form of strips, but only in the size that they cover the respective contact area K.

The separation of the columns 6 , 12 , 13 , 14 , 15 by means of seams 7 ensures that adjacent columns do not slip and that there is no electrical short circuit between adjacent columns, which could falsify the measurement result. It can also be provided, which is not shown here, that rows are separated from one another by seams.

In the exemplary embodiment shown here, the sensor has two rows and two columns on. This illustration was chosen for the sake of clarity, with a sensor according to the invention generally more than two rows and more than two columns having. However, the measuring principle itself can also be implemented if only one Column and a row are present, which form a contact area K.

It is not imperative to design the resistance elements 5 , 15 and the electrically conductive elements 4 , 14 in the form of strips. Rather, it can also be provided that each contact area K is formed by a separate resistance element 5 and a further separate resistance element 15 , between which an element 6 made of poorly conductive material can be arranged. It can also be provided that the resistance elements 5 , 15 are contacted only at the contact areas K by the electrically conductive elements 4 , 14 . Furthermore, it can be provided that each contact area K is contacted by a separate electrically conductive element 4 on the side formed by the first resistance element 5 and by a separate electrically conductive element 14 on the side formed by the further resistance element 15 .

Fig. 4 shows a second embodiment schematically illustrates a sensor according to the invention. This in turn has a number of strip-shaped resistance elements 5 arranged in rows and a number of strip-shaped resistance elements 15 arranged in columns, which in turn form a matrix-like grid of contact areas K. Instead of the metal strips 4 , 14 of the first exemplary embodiment, electrically conductive fibers 20 are embedded in the resistance elements 5 , 15 . The contact areas K of the resistance elements 5 , 15 can be subjected to voltage via the fibers 20 , which are formed from metal in this exemplary embodiment. For this purpose, the metal fibers 20 can be connected to an evaluation device via connecting lines (not shown here). The fibers 20 run in a meandering shape in the resistance elements 5 , 15 , so that when the resistance elements 5 , 15 are stretched, only the meander of the fibers 20 is pulled apart, but the fibers 20 are not stretched or torn off. For the sake of simplicity, further components of the sensor have been omitted in the second exemplary embodiment. It goes without saying that the sensor according to the second exemplary embodiment can also have one or more elements 6 made of poorly conductive material between the resistance elements 5 , 15 at the contact points K, and can be integrated into and fixed to a fabric, as in the case of first embodiment described. As with the first embodiment, it is also not essential that the resistive elements 5, 15 as shown in Fig. 4, can be contacted over its entire length by fibers 20. It may be sufficient if the resistance elements 5 , 15 are contacted by the fibers 20 only at the contact areas K or at selected contact areas K.

Fig. 5 shows a different embodiment from the first embodiment of the elements 6 of poorly conductive material. In this case, the elements 6 made of poorly conductive material are not designed as strips, but as components of a sheet-like layer 16 . The layer 16 has a plurality of elements 16 made of poorly conductive material, the number of which corresponds to the number of contact areas K of the sensor. In the layer 16 , the elements 6 made of poorly conductive material are arranged in a checkerboard pattern and delimited from one another by column and row regions 6 a made of an insulating material. The integration of the elements 6 made of poorly conductive material in the layer 16 has the advantage that the layer 16 can be inserted as a whole between the resistance elements 5 , 15 during the manufacture of the sensor, which results in a lower manufacturing expenditure than if individual elements 6 made of poorly conductive material between the resistance elements 5 , 15 must be used.

Fig. 6 shows a different arrangement of the first embodiment of the strip-shaped resistance members 15. These are integral parts of a sheet-like assembly 25 in which the resistor elements 15 are separated by insulating areas 15 a of each other. Here, as with which the elements 6 containing from poorly conductive material layer 16 results in the advantage that the resistance elements 15 not individually in the preparation of the sensor in these must be introduced, but that only the sheet-like arrangement with the resistor elements 15 as a mounting portion must be introduced into the sensor. This also results in a reduced manufacturing effort for the sensor.

Claims (14)

1. Sensor for location and / or time-resolving force or pressure measurement, the resistance elements ( 5 , 15 ), which form a matrix-like grid with rows and columns of spaced-apart contact areas (K) of the resistance elements ( 5 , 15 ), an electrical Resistance at a contact area (K) of two resistance elements ( 5 , 15 ) depends on the force or pressure load of the contact area (K), characterized in that at least one of the resistance elements ( 5 , 15 ) passes through at least one of the contact areas (K) an electrically conductive element ( 4 , 14 ; 20 ) which is in electrical contact with the resistance element ( 5 , 15 ) at this contact area (K) can be subjected to voltage. 2. Sensor according to claim 1, characterized in that the resistance elements ( 5 , 15 ) are strip-shaped and are arranged in rows and columns. 3. Sensor according to claim 1 or 2, characterized in that the electrically conductive element ( 4 , 14 ) is strip-shaped and is arranged along a row or column of contact areas (K) of the resistance elements ( 5 , 15 ). 4. Sensor according to claim 3, characterized in that the strip-shaped electrically conductive element ( 4 , 14 ) along a strip-shaped resistance element ( 5 , 15 ) is arranged in contact with this. 5. Sensor according to claim 1 or 2, characterized in that the electrically conductive element is an electrically conductive fiber ( 20 ) embedded in a resistance element ( 5 , 15 ). 6. Sensor according to claim 2 and 5, characterized in that the electrically conductive fiber ( 20 ) extends at least over part of the length, preferably over the entire length of the strip-shaped resistance element ( 5 , 15 ). 7. Sensor according to claim 6, characterized in that the electrically conductive fiber ( 20 ) in the resistance element ( 5 , 15 ) is meandering. 8. Sensor according to any one of the preceding claims, characterized in that an element ( 6 ) made of a poorly conductive material is arranged at least on part of the contact areas (K) between the resistance elements ( 5 , 15 ). 9. Sensor according to claim 8, characterized in that the element ( 6 ) made of poorly conductive material covers the entire surface of the relevant contact area (K). 10. Sensor according to claim 2 and 8 or 9, characterized in that the element ( 6 ) or the elements ( 6 ) of poorly conductive material is or are strip-shaped and along one or more strip-shaped resistance element (s) ( 5 , 15th ) is or are arranged. 11. Sensor according to one of claims 2 to 10, characterized in that a layer ( 16 ) is arranged between the resistance elements ( 5 ) arranged in rows and the resistance elements ( 15 ) arranged in columns, which insulating column and row areas ( 6 a ) and by these column and row areas ( 6 a) delimited, poorly conductive elements ( 6 ), which are arranged in a checkerboard pattern, and which are arranged on the contact areas (K) of the resistance elements ( 5 , 15 ) between them. 12. Sensor according to one of the preceding claims, characterized in that the matrix-like grid is arranged in a fabric ( 1 , 2 , 11 , 12 ) and that electrodes ( 3 , 13 ) are attached to this fabric, which are arranged in rows and columns and which in turn contact the electrically conductive elements ( 4 , 14 ). 13. Sensor according to one of the preceding claims, characterized in that several, preferably all in columns ( 15 ) and / or more, preferably all arranged in rows resistance elements ( 5 ) are integrated in a flat arrangement ( 25 ) and by electrically insulating areas ( 15 a) are separated from each other. 14. Sensor according to one of the preceding claims, characterized in that the electrically conductive element ( 4 , 14 , 20 ) or the electrically conductive elements ( 4 , 14 , 20 ) is or can be connected to at least one connecting line with an evaluation device.