WO1994021492A1

WO1994021492A1 - Sensor to be fitted in or on a vehicle

Info

Publication number: WO1994021492A1
Application number: PCT/DE1994/000220
Authority: WO
Inventors: Lorenz Pfau; Manfred Frimberger; Peter Bauer
Original assignee: Siemens Aktiengesellschaft
Priority date: 1993-03-16
Filing date: 1994-03-01
Publication date: 1994-09-29
Also published as: DE4308353C1; EP0688277A1

Abstract

A sensor for the early diagnosis of the consequences of accidents to be fitted in or on a vehicle. In order to detect a mechanical change in shape it contains several parallel electrically conductive strips with a considerable length in comparison with the strip width. At least a first strip (W) has a clearly measurable ohmic resistance (Rx) and, on distortion, comes into galvanic contact with a second strip (W) so that, in the event of an accident, the position (O) of the contact can be at least approximately determined by measuring the ohmic resistance (Rx) between terminals (A) of the first and second strips (W). At least a third strip (C) acts capacitively with another of the strips (C) on distortion so that, in the event of an accident, the size of the area of the third strip (C) affected by the distortion can be at least approximately determined by measuring the change in capacitance (Cd) between the third and the other strips (C).

Description

Sensor to be installed in or on a vehicle

The invention is based on the sensor defined in the preamble of claim 1, to be attached to or on a vehicle, which is known per se, cf. DE-A-2 212 190. This sensor can e.g. in an accident - e.g. by upsetting and / or bending - deforming. It is formed by a long contact strip made of elastic material with a particularly knife-like rod-shaped contact that cuts through the material in the event of an accident and makes an electrical connection to a long counter contact.

A similar sensor intended for a robot is the

EP-A1-0 229 601 previously known. It is a very long contact bar, in which the location where the bar is pressed is determined by a resistance measurement.

A sensor for motor vehicles working according to a capacitive concept is characterized by the

DE-Al-37 29 021 previously known. It can be used in particular to determine the depth and the rate of deformation of a dent - e.g. in the side door of the car - measure. A similar capacitive pressure sensor, which is primarily intended to serve as an underwater microphone, is already known from the - FR -A-l 532 262.

In an accident, the sensor according to the invention is intended to enable as early as possible a detection of the impact or the deformation of the vehicle body, and at least in many cases also make certain statements about the location of the impact or the deformation of the vehicle body. The invention is therefore also suitable for the early diagnosis of the consequences of an accident. It is supposed to make a particularly quick diagnosis possible, so that it can be used, for example, for the electronic control of an airbag for side-impact protection if an unauthorized vehicle hits the side door with force. In addition, the invention is suitable for recognizing whether and to what extent a seat or a storage area is occupied, and whether the pressure on this seat or on this storage area changes in the event of an accident.

The task of enabling the early detection of the deformation of the vehicle in one of its places, e.g. when using the sensor to detect an accident, the particularly rapid early detection of the deformation of the sensor and thus of the type of impact, at least in many cases also certain statements about the location of the impact and the area along which the sensor deforms was, z enable, and when using this sensor to detect the occupancy of a seat or a storage surface, to enable the or and the strength or area of the deformation of the sensor and thus the type of occupancy, according to the invention by the in claim 1 defined object solved.

The objects defined in the subclaims allow additional advantages to be achieved. Et al namely allow the additional measures according to the patent claim

2, to achieve a particularly space-saving and low-cost solution,

3, to be able to use commercially available strip-shaped capacitor strips,

4, to achieve a particularly thin / flat, although wide arrangement of the strips, 5, to achieve a particularly narrow, if somewhat thicker solution, with this variant of the invention the location of the maximum deformation of the first, resistive / galvanically acting strip advantageously being exactly the same as the location of the maximum deformation of the third, capacitive-acting strip,

6, offer a particularly favorable solution for mass production,

7, the strips can be attached to the vehicle particularly easily,

8, when the strips are deformed by means of air as an additional dielectric, a particularly large and particularly easily and precisely measurable change in capacitance can be achieved without - because of the additional solid insulating layer - risking that the deformation immediately results in a short circuit between the third and the other Stripes can arise

9, to offer a particularly favorable solution for controlling an airbag that responds to side impacts, 10 to offer a solution by means of which the local deformation of the body can be measured very quickly and precisely, regardless of whether the bodywork is locally there is very stiff or very soft, and 11 to check the occupancy of a seat or a pad.

The invention and further developments thereof are further explained on the basis of the diagrams of exemplary embodiments of the invention shown in the figures, which have been shown as simply as possible for the sake of clarity. The figure shows

1 shows a cross section perpendicular to the longitudinal direction of the strip in an example of a variant of the invention, in which all the strips are arranged one above the other on a body part, 2 a cross section perpendicular to the longitudinal direction of the strip in an example of a variant of the invention, in which the resistive / galvanic streak 3 and 4, schemes for explaining the measurement and evaluating the measurement results in the examples of the invention shown in FIG. 1 and in FIG. 2, and 5, 6 and 7, are arranged next to the capacitively acting strips on a body part Example of the attachment of the variants of the invention shown in FIGS. 1 and 2 a a tubular stiffening in the lower region of a side door of a motor vehicle.

All of the figures thus show special aspects of exemplary embodiments of the invention. It is a sensor that is used, for example, in a vehicle door T, cf. di Figure 7, is to be attached and which is deformed in an accident.

The sensor is suitable for early diagnosis of the consequences of an accident. It is suitable for the detection of location, time and section length / area on which the sensor is deformed mechanically, i.e. was crushed by the collision with the foreign obstacle.

Figures 1 and 2 show cross sections through two exemplary embodiments. The sensor according to the invention has at least three - in FIGS. 1 and 2 four, by way of example - electrically conductive strips C, W, which run parallel over a large longitudinal extent in comparison with the strip width and on a body part K - for example according to FIGS. 5 to 7 on one tubular stiffener inside the side door T of a motor vehicle - are attached. These strips W, C, viewed separately, serve different purposes. However, only together do they enable the early diagnosis of location, exact time and extent of the change in shape of the vehicle body in the event of an accident. The sensor can detect different sizes here, depending on how the sensor was attached to the carrier object, i.e. whether the sensor is squeezed transversely to its longitudinal extent by an obstacle / foreign vehicle or whether the sensor is attached to a vehicle part, as it is compressed / deformed by the impact and thus the sensor is also deformed, and also depending on how the sensor signals are evaluated.

Consider as an example the sensor S on the tubular stiffening body R in the lower half of the door T cf. Figures 5 to 7. The sensor according to the invention has only a small width compared to its great length. This sensor S is attached at a certain distance from the outer panel of the door T. In this example, the sensor according to the invention is squeezed by an accident from the "obstacle" pressing the door T if the outer panel of the door T is on the sensor and thus on the body part K or R, cf. Figures 1, 5 and 6, on which the sensor according to the invention is attached, presses. - A foreign vehicle, which drives the vehicle equipped with the invention against the side door T, is here and also below also referred to for brevity as an "obstacle, even if this obstacle has its own speed. The sensor then allows not only de Time and place, but also to determine the length or area along which the sensor is squeezed in the event of an accident, depending on the location of the impact and the width with which the obstacle acts on the sensor.

The sensor shown in FIGS. 5 to 7 is, however, only "indirectly" squeezed in the event of a side impact, because it is not directly attached to an outer part (outer skin) of the vehicle, but rather to a vehicle part which is at a certain distance from the outer part . The This sensor is only "directly" squeezed in the event of a side impact if it is attached to the outside of the outer skin of the door T. In both cases, however, as will be described in more detail below, the sensor can not only display the exact location in the direction of its longitudinal extent at which it is squeezed. It can also indicate the length of the section along which it is squeezed together by the obstacle. In principle, the sensor according to the invention is even suitable for indicating the severity of the accident, as will also be explained later.

The sensor according to the invention can, however, also be mounted in the vehicle in such a way that, at least initially, it is not yet directly or indirectly squeezed by the obstacle in the aforementioned sense. The sensor according to the invention can namely also on a vehicle part lying inside the vehicle - e.g. on solid I-beams of the chassis - which is only compressed in its longitudinal direction, instead of being bent by pressure in the transverse direction. The sensor can perform the task of determining whether such a vehicle part is compressed by the accident, i.e. is bent so that the longitudinal axis of the sensor is also bent without the obstacle pressing directly to the side of the sensor according to the invention.

The sensor according to the invention is therefore suitable for various types of measurements of the consequences of an accident. In addition, the sensor signals can be evaluated differently, as will be explained later. But first, let's look at the structure of the sensor:

At least a first of the strips W - in FIGS. 1 and 2 even both strips W - has a clearly measurable ohmic series resistance. This strip W lies parallel to a second strip, which is also designated W in FIGS. 1 and 2. If the sensor is squeezed and / or compressed in the event of an accident, a short-circuit occurs in any case at one point between the first and the second strip W by mutual contact of these strips W arranged in parallel, cf. the circuit diagram in Figure 3. At the location of this contact, there is a galvanic contact between the first strip W and the second strip W.

In the event of an accident, location 0 can be measured indirectly at least approximately by measuring the ohmic resistance Rx between connections A of the first and second strip W. The control electronics of the occupant protection devices that can be connected to the connections A, e.g. of airbags and / or belt, can be controlled depending on the initial location 0 of the deformation - a very important criterion for the accident. From this electrical resistance Rx, cf. FIG. 3, which can have values between ZERO and R a, can be determined in a simple and quick manner both the location 0 of the contact and the time of this contact. The measuring accuracy for location 0 is higher the more homogeneous the resistance strip W is in its longitudinal direction. The measurement accuracy can be further improved if both the first strip W and the second strip W each have relatively large ohmic resistances in their longitudinal direction. The optimum resistance value Rmax for a certain sensor structure can be determined by experiments, whereby it should be noted that measurement errors due to inductive and or capacitive interference, e.g. starting from the engine ignition can be largely avoided.

The invention also allows the length along the longitudinal extent of the sensor to be affected by a squeeze / compression, at least approximately by means of the capacitive strips C according to the measurement concept shown in FIG. This is because at least a third of the strips acts according to the invention when the sensor is deformed capacitively with another of the strips, cf. the fourth strip C in Figures 1 and 2, together. In the event of an accident, the control electronics can determine the magnitude of the change in capacitance C between the strips C at the outer connections A - shortly before, un shortly after the ohmic contact between the strips W occurs at point 0, cf. FIG. 4. This value Cd of the change in capacity results according to the diagram shown in FIG. 4 as a change in the value Co which represents the capacity value between the strips C before the accident. From the value Cd, the control electronics can at least approximate the size of the area affected by the deformation between the third and the other strip C. From the value Cd, the control electronics can also determine the length along which the sensor was squeezed: this length is obtained by dividing the deformed area of the sensor corresponding to the value Cd by the width of its capacitively acting strip C.

The invention thus makes it possible to determine both the location 0 of the deformation of the sensor and the associated point in time as well as the length along the sensor affected by the deformation.

In principle, the invention even allows the intensity of the accident to be determined from the value Cd, if one does not prefer to use an additional sensor for this purpose, which emits analog signals corresponding to this intensity (eg deceleration / acceleration). The speed at which the capacity Cd changes during the accident can in principle also determine the intensity of the accident for the location 0 in question (location of the beginning deformation). From this, the evaluation electronics can even predict the consequences of the accident to be expected in the next few moments. In order to track the change over time of the value Cd to the in 4 to detect the connections A shown, one has to measure the slope with correspondingly high measuring frequencies, with which Cd changes. For this purpose, one can measure the amplitude of the current surge occurring at connections A in the accident through differentiating elements.

Through the rapid and fairly precise measurement of the location 0 de the beginning deformation of the sensor and the measurement of the associated time using the resistance value Rx, as well as through the rapid and fairly precise measurement of the squeezed surface of the sensor by measuring Cd, possibly also by measuring the intensity of the impact, in particular by measuring the size and, above all, the speed of the capacity change Cd at this point of the beginning deformation, the invention achieves a particularly rapid and meaningful early diagnosis of an impact or a deformation of the vehicle body and the expected consequences of the accident . Above all by crash test, one can gain valuable information on the control of the occupant protection system, in particular from the location of the location 0 and from the value Cd, in order to operate the control electronics of the occupant protection device in such a way that the best possible protection of the vehicle occupants can be achieved.

In order to achieve a particularly thin / flat, even if then relatively wide arrangement of the strips W, C, the ohmic sensor half, formed from the first strip W and the second strip W, can be formed next to the side according to the diagram shown in FIG the capacitive sensor half formed from the third strip C and a fourth strip C, attach. In principle, you can even make one of the strips W, either the lower one lying on the body K or the upper strip W, particularly wide, so that it forms a single over-wide strip W / C together with the adjacent strip C and the sensor according to the invention then only has three strips W, C. But you can also achieve a - in comparison to the variant of the invention shown in Figure 2 - particularly narrow, if somewhat thicker solution by arranging all the strips C, W stacked, see. FIG. 1. In this variant of the invention, the location 0 of the beginning deformation for the first, oh sh / galvanically acting strip W is advantageously at exactly the same location 0 at which the third, capacitively acting strip C is also deformed. With this arrangement one above the other, the lower, approximately central second strip W can be identical to the upper, approximately central strip C, so that the sensor then has only three instead of the four strips W, C shown in FIG .

In both variants, a particularly space-saving and material-saving solution can thus be achieved in that the other strip C is the first or the second strip W, so that the sensor has a total of three parallel strips W, C.

Commercially available strip-shaped capacitor strips which already contain the two strips C can be used for the invention, at least if the sensor is not formed from three but from four strips, i.e. if the other strip C represents a fourth strip C, cf. FIGS. 1 and 2. A solution which is particularly favorable for mass production can be achieved if tape-like, mutually superposed conductive foils are used for both the two strips C and for the two strips W, which are in the form of tape-shaped goods are manufactured.

FIGS. 1 and 2 indicate that the strips W, c can each be attached to support layers S, which, for example, represent plastic strips S and are coated with the material of the strips W, C. To protect against contamination of the air spaces L between the strips W, c Side walls B can be attached, which can also be formed from a plastic, for example. In order then to be able to attach the strips particularly easily to the vehicle, at least some of the surfaces S can additionally be covered with a self-adhesive layer.

Air can be used as a dielectric in order to enable the largest possible changes in capacitance value Cd when the capacitively acting strips are deformed. If you only use air L as the dielectric between the third and the other strip C, then you risk that in the event of an accident, the deformation of the sensor immediately results in a short circuit between the third and the other strip C. In order to avoid this short circuit and still achieve a large change in capacitance value Cd, one can use air between the third and the other strip C as a dielectric and also attach a solid insulating layer I, cf. Figures 1 and 2. If the solid insulator I is very little compressible, the measurement of the amount of Cd is particularly accurate.

In order to offer a particularly favorable solution for controlling an airbag to be triggered in a side impact, the sensor S, W, C according to the invention can, as already described, be connected to a - e.g. Attach tubular reinforcement R inside a side door T of the vehicle.

But you can the sensor S, W, c auc directly at other points of the vehicle, e.g. on an outer panel of the vehicle in the front area, rear area or on the fenders, also in the roof or on the floor panel or even on rigid parts of the chassis such as on the frame that supports the engine. The invention thus also offers the possibility of determining the location 0, the time and the intensity of local accident consequences very quickly and precisely at such other locations in the vehicle. So you can be very local with the invention Determine deformations of any body parts, regardless of whether locally the body is particularly stiff or very soft.

In addition, the invention is also suitable for other applications in the vehicle, for example as a seat contact for recognizing whether and to what width the seat is occupied. In the event of an accident, such a seat contact can also be used to recognize whether the person sitting there up to now - or an object lying on the seat, for example a suitcase or a package - is already beginning to fall out of the seat.

List of reference numbers

A connections

B side walls

C stripes (as capacity)

Cd capacity change

Co capacity value (before the accident)

Cx capacity value (in the event of an accident) d (changed) distance

I (solid) insulation layer

K body part

0 deformation site

R (tubular) stiffening part

Rx series resistance value

S carrier films

T (lower half of a) side door

W stripes (as resistance track)

Claims

1. In or on a vehicle sensor to be included, which contains a plurality of electrically conductive strips to detect a mechanical change in shape, which run parallel over a large longitudinal extension compared to the strip width, characterized in that a) at least a first of the strips (W) a clearly measurable ohmic series resistance (Rx) and at

Deformation comes into galvanic contact with a second of the strips (W), so that in the event of an accident the location (0) of the contact at least by measuring the ohmic resistance (Rx) between connections (A) of the first and second strips (W) is approximately measurable, and b) at least a third of the strips (C) capacitively cooperates with another of the strips (C) in the deformation of the sensor such that in the event of an accident the size of the surface of the third strip (C ) can be measured at least approximately by measuring the change in capacitance (Cd) between the third and the other strip (C).

2. Sensor according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the other strip (C) is the first or the second strip (W).

3. Sensor according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the other strip (C) is a fourth strip (C).

4. Sensor according to claim 3, characterized in that - the first and second strips (W) are attached laterally next to the third and fourth strips (C).

5. Sensor according to one of the preceding claims, so that all strips (C, W) are arranged one above the other in a layered manner.

6. Sensor according to one of the preceding claims, so that at least two of the strips (C, W) are produced as strip-like, superimposed conductive foils in the form of strip-shaped piece goods.

7. Sensor according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that - at least one of its surfaces (S) is covered with a self-adhesive layer.

8. Sensor according to one of the preceding claims, so that an air gap is provided between the third and the other strip (C) al dielectric as well as a solid insulating layer (I) is applied between the third and the other strip (C).

9. Sensor according to one of the preceding claims, d a d u r c h g e k e n n e e c h n e t that it is attached to a stiffener (R) within a side door (T) of the vehicle.

10. Sensor according to one of claims 1 to 8, d a d u r c h g e k e n n z e i c h n e t that it is attached to an outer panel of the vehicle.

11. Sensor according to one of the claims 1 to 8, d a d u r c h g e k e n n e e c h n e t that - it is attached to a seat or on a storage surface.