DE102013000645A1 - Device for detecting occupancy of luxury-class vehicle seat, has evaluation electronics detecting surface element change i.e. change of position in vehicle seat, where change is produced due to weight of vehicle occupant - Google Patents

Abstract

The device has electrically conductive surface elements (6.1-9.1, 6.2-9.2) applied on a seat cushion-pad foam part (4) of a seat cushion-pad element (2) and a backrest-pad foam part (5) of a backrest-pad element (3). An evaluation electronics detects surface element change i.e. change of a position in a vehicle seat (1), where the change is produced due to a weight of a vehicle occupant (I). The evaluation electronics computes a seat pressure distribution of the associated pad elements from the change of relative positions between the surface elements. Compression of the pad elements is used. An independent claim is also included for a method for detecting occupancy of a vehicle seat.

Description

The invention relates to a device and a method for detecting a seat occupancy of a vehicle seat.

The invention further relates to a vehicle seat with a device for detecting a seat occupancy.

State of the art

Vehicle seats are generally known, which include devices for detecting a seat occupancy of the vehicle seat. The devices have sensors, from the signals of which a seat occupancy state and / or a seat pressure distribution of the vehicle seat can be derived.

From the EP 1 211 143 B1 is a generic device for seat occupancy detection in a vehicle seat known. In this case, a sensor mat, which has a multiplicity of resistive sensor cells, is arranged in a seat surface of a vehicle seat. The sensor cells change their ohmic resistance under pressure.

The sensor cells are arranged within the sensor mat in the form of a two-dimensional matrix in a plurality of rows and columns. By measuring the ohmic resistance of the said sensor cells, the pressure distribution on the seat surface of the vehicle seat can thus be determined, from which it is possible to deduce the type of seat occupancy, for example whether an adult or a child is sitting on the seat.

For measuring the ohmic resistance of the individual sensor cells, a circuit is provided which has, inter alia, two multiplexers. These multiplexers are controlled in time sequence by a control unit such that the ohmic resistances of the individual sensor cells are measured one after the other.

From the EP 1 731 378 B1 is also a generic device for seat occupancy detection in a vehicle seat known. In this case, a sensor mat, which has a multiplicity of capacitive sensor cells, is arranged in a seat surface of a vehicle seat. The sensor cells change their capacity under pressure. The sensor cells are electrically connected in parallel and each connected to a connection with a common conductor. The respective second terminals of each sensor cell are successively connected to a control unit, where the capacitances of the individual sensor cells are measured.

A method for detecting the seat occupancy and the seat pressure distribution by means of pneumatic and / or hydraulic sensors, which interact with pneumatic and / or hydraulic lifting elements, discloses the WO 2009/059768 A1 , The pressure that is exerted on the seat by a vehicle occupant is detected by means of at least one pneumatic and / or hydraulic sensor and a current pressure profile is determined. The pressure profile is compared with a predetermined, ergonomically optimal pressure profile and the seat is adjusted in the direction of this ergonomically optimal pressure profile. One or more of the seat adjustment sizes seat longitudinal position, seat inclination, seat height, seat depth, backrest inclination, backrest width, lumbar depth and lumbar height are set. Since the pneumatic and / or hydraulic sensors and lifting elements used are very expensive, the method and the associated device is only suitable for luxury vehicles.

All known methods are based on the use of pressure sensors, which must be introduced as additional, executed separately from the foam part of the seat cushion components in the seat. Such sensors have a high rigidity and thus negatively affect the seating comfort. In addition, the cost of such sensors are high.

task

Object of the present invention is to provide a comparison with the prior art improved, in particular cost-effective device for detecting a seat occupancy of a vehicle seat, an improved method for detecting a seat occupancy of a vehicle seat and a vehicle seat with a device for detecting a seat occupancy.

solution

This object is achieved with a device for detecting a seat occupancy of a vehicle seat according to claim 1. The device comprises at least one upholstery element, which is provided with at least one coating, and evaluation electronics, which detect a change in the at least one coating caused by the weight of a vehicle occupant, in particular their change of position in the vehicle seat. By using the at least one coating can be dispensed with an additional sensor or an additional sensor mat, so that costs and weight can be saved.

At least one extensively upholstered element arranged in a seat cushion area and / or a backrest area of the vehicle seat, which is elastically deformable at least in a direction substantially perpendicular to a seat surface or backrest surface, has the at least one electrically conductive coating.

Advantageously, arranged on substantially parallel to the seat or backrest surface, opposite padding surfaces at least one surface pair of opposing and electrically conductive, designed as surface elements coatings, which are each associated with a particular capacitive distance sensor, in a conventional manner in each case with a voltage source and is connected to an evaluation as serving detection unit. The capacitive sensor operates based on the change in capacitance of a single capacitor or a whole capacitor system.

Usually, the surface elements of the capacitor are charged with AC voltage or an alternating current.

However, one of the surface elements can also be connected to a positive pole of a (DC) voltage source or a current source (with constant current) and the remaining remaining surface element to a negative pole of the voltage source or the power source.

When occupying the vehicle seat, the cushion element is compressed in the direction substantially perpendicular to the seat surface or backrest surface, so that a distance between the surface elements is reduced. From this reduction in distance results - depending on the operation and evaluation - a change in capacity and / or in the electrical voltage between the surface elements. For detecting this change in capacitance and / or voltage, at least one detection unit is provided, wherein a status of the seat occupancy can be detected on the basis of a comparison of the detected capacitance and / or voltage with a predetermined capacitance and / or voltage setpoint.

The device according to the invention makes it possible, in a particularly advantageous manner due to the utilization of the compression of the padding element, to realize a simple, cost-effective and reliable detection of the seat occupancy. On the other hand, complicated and expensive sensors and / or sensor mats known from the prior art are not required for determining the seat occupancy. Also, due to the detection of the compression of the cushioning member based on the capacity change or the change in the electric voltage, it is possible to easily determine a distribution and a size of a pressure applied to the seat surface and / or the seat back.

Advantageously, at least one coating is applied to a padding foam part of the at least one padding element. However, it is also possible that the coating is applied to a cover or a further textile layer of the cushioning element.

It can be sensed the distance of a single coating to a seat structure part. However, it is particularly advantageous if at least one pad foam part has two coatings which represent a first surface element and a second surface element whose relative position is detected relative to one another and which together form a pair of surfaces. The interacting sensor surfaces are then part of a single seat component, so that the sensor can be checked for operability before final assembly of the vehicle seat.

An inexpensive possibility of detecting a seat pressure distribution of the upholstery element is achieved in that the upholstery foam part has at least two pairs of surfaces and the transmitter calculates a seat pressure distribution of the associated upholstery element from the change in the respective relative positions between the first surface elements and the second surface elements of the at least two surface pairs.

Advantageously, at least one surface element of a surface pair is introduced into a depression of the padding foam part introduced perpendicularly to the surface of the padding element, so that the first and second surface elements of each surface pair have a smaller distance from one another than the opposing surfaces of the padding element or padding foam part.

When occupying the vehicle seat, the cushioning element is compressed in the direction substantially perpendicular to the seat surface or backrest surface, so that the distance between the surface elements is reduced. This reduction in distance results in a change in at least one electrical variable of the capacitor comprising the surface elements, in particular the increase in the capacitance. The detected electrical variable, in particular the voltage and / or the ascertained capacitance is compared with a predefined setpoint value, wherein in the case of a particularly negative deviation of the detected values from the setpoint values, a seat occupancy status is set to "occupied".

The object is also achieved with a method for detecting a seat occupancy of a vehicle seat, in which a generated by the weight of the vehicle occupant compression of at least one coating cushioning element, in particular a cushion foam part comprising at least one coating is sensed.

In the case of preferably electrically conductive surface elements as a coating, these are advantageously subjected to an electrical voltage, in particular an electrical alternating voltage or a constant current intensity. By means of a detection unit, the electrical voltage between the surface elements and / or the capacitance of the capacitor comprising the surface elements is then detected and the distance between the surface elements is determined therefrom in a manner known per se.

Advantageously, the method comprises the sensing of the distance between two opposing coatings in the compression direction. However, it is also possible to sense a lateral shift or an angle change between the coatings using known evaluation methods.

Reliable sensing is achieved by providing the coatings with electrical conductivity and measuring and evaluating at least one electrical quantity of at least one coating as a result of the generated compression.

In an expanded version of the method, the distances are sensed by a plurality of opposing pairs of coatings in the compression direction, and from this a seat pressure distribution is calculated, in particular by means of evaluation electronics.

The inventive method allows in a particularly advantageous manner due to the exploitation of the compression of the cushion element easy to realizable, cost-effective and reliable detection of seat occupancy, which is due to the detection of the compression of the cushion element, vorteihafterweise on the basis of capacity and / or electrical voltage possible to easily determine the distribution of pressure exerted on the seat and / or seat back.

The coating of the surfaces of the seat cushion cushion element and / or the seat back upholstery element, in particular the respective upholstery foam part, can be done in different ways. Advantageously, electrically conductive dyes, paints or dispersions with metallic or carbon-containing substances, metal foils or other conductive coatings, in particular with so-called carbon nano tubes. Also conceivable are surface elements made of electrically conductive fibers, threads, wires or electrolytes.

In addition to the evaluation of changes in the capacitance and / or the voltage, the evaluation of inductors or resistors in principle also in a conventional manner conceivable as an optical evaluation of the distances between the two surface elements of a surface pair.

The invention is further achieved with a vehicle seat, which comprises a device according to the invention for detecting a seat occupancy.

Advantageous embodiments, which can be used individually or in combination with each other, are the subject of the dependent claims.

Figures and embodiments of the invention

In the following the invention is explained in more detail with reference to an advantageous embodiment shown in the figures. However, the invention is not limited to this embodiment. Show it:

1 FIG. 2 schematically shows a first sectional view of a vehicle seat before being loaded by a vehicle occupant, FIG.

2 FIG. 2 schematically shows a second sectional view of the vehicle seat with the load on the vehicle occupant and FIG

3 schematically a seat print image.

Corresponding parts are provided in all figures with the same reference numerals.

In 1 is a first sectional view of a vehicle seat 1 and a vehicle occupant I shown.

The vehicle seat 1 includes a seat cushion cushioning element 2 and a seatback cushioning member 3 and is designed for use as a vehicle front seat or vehicle rear seat.

For operating safety devices of a vehicle, in particular reversibly and irreversibly operable restraint devices for a vehicle occupant I , it is necessary to have a seat occupancy status of the vehicle seat 1 to capture the the vehicle seat 1 assigned restraint devices only if necessary to drive when a vehicle occupant I on the respective vehicle seat 1 located.

This includes the vehicle seat 1 a device for detecting the seat occupancy of the same. The device comprises in the illustrated embodiment a in a seat cushion area of the vehicle seat 1 arranged, largely flat seat cushion pad foam part 4 and a in a back region of the vehicle seat 1 arranged seat back upholstery foam part 5 , The seat cushion upholstery foam part 4 forms together with other upholstery elements, in particular a cover, the seat cushion cushion element 2 , The seat back upholstery foam part 5 forms together with other upholstery elements, in particular a cover, the seat back upholstery element 3 ,

The seat cushion upholstery foam part 4 and the seat back upholstery foam part 5 are each at least substantially perpendicular to a seat surface direction X or perpendicular to a backrest Y Y elastically deformable. The seat cushion upholstery foam part 4 and the seat back upholstery foam part 5 are made of an elastically compressible foam material with a customary for this material compliance, each of which is a spring constant for the seat cushion pad foam part 4 and for the seat back upholstery foam part 5 results.

Furthermore, the device comprises pairs of surfaces 6 to 9 of electrically conductive surface elements 6.1 . 6.2 . 7.1 . 7.2 . 8.1 . 8.2 . 9.1 . 9.2 which in particular arranged on substantially parallel to the seat or backrest surface, opposite padding surfaces, in particular foam part surfaces of the foam padding parts 4 . 5 are arranged.

The first two surface elements 6.1 and 7.1 are on the bottom of the seat cushion upholstery foam part 4 appropriate; the two second surface elements 6.2 and 7.2 are on top of the seat cushion upholstery foam part 4 appropriate. The first two surface elements 8.1 and 9.1 are on the back of the seat back upholstery foam part 3 appropriate; the two second surface elements 8.2 and 9.2 are on the front of the seat back upholstery foam part 3 appropriate.

The surface elements 6.1 . 6.2 . 7.1 . 7.2 . 8.1 . 8.2 . 9.1 . 9.2 be by means of a partial coating of the cushioning elements 2 . 3 , in particular the foam part surfaces of the foam upholstery parts 4 . 5 generated. Alternatively, a complete coating is possible.

The area pairs 6 to 9 are connected in a manner not shown in each case with a voltage source, in particular an AC voltage source. When using a power source, for example, each one of the surface elements 6.1 . 7.1 . 8.1 . 9.1 with a positive pole of the voltage source and the remaining remaining surface elements 6.2 . 7.2 . 8.2 . 9.2 connected to a negative pole of the voltage source.

The area pairs 6 to 9 the surface elements 6.1 / 6.2 . 7.1 / 7.2 . 8.1 / 8.2 . 9.1 / 9.2 in the present case each form an electrical capacitance, wherein between the respectively associated surface elements 6.1 / 6.2 . 7.1 / 7.2 . 8.1 / 8.2 and 9.1 / 9.2 an electrical voltage is applied to the voltage source.

When occupying the vehicle seat 1 with the vehicle occupants I become due to its mass the foam foam parts 4 . 5 compressed, so that the distances between the respective surface elements 6.1 / 6.2 . 7.1 / 7.2 . 8.1 / 8.2 and 9.1 / 9.2 reduce.

The difference between the upholstery foam parts 4 . 5 in the uncompressed state and in the compressed state show the 1 and 2 , in which 1 the uncompressed state and 2 represents the compressed state.

From the reduction in distance between the associated surface elements 6.1 . 6.2 . 7.1 . 7.2 . 8.1 . 8.2 . 9.1 . 9.2 results in a reduction of the capacitance and / or the electrical voltage between these, from which the status of the seat occupancy can be derived.

For detecting the capacitances and / or the electrical voltage, in particular the electrical alternating voltage and the capacitance and / or voltage change, at least one detection unit (not shown) is provided. If the detected electrical variable falls below a predetermined desired value, which in particular corresponds to the value of the capacitance and / or the electrical voltage between the surface elements 6.1 . 6.2 . 7.1 . 7.2 . 8.1 . 8.2 . 9.1 . 9.2 in the uncompressed state of the foam upholstery parts 4 . 5 corresponds to an occupied vehicle seat 1 closed.

In order to amplify the detected voltage signal and thus increase the reliability of detection, the area pairs forming the electrical capacitances are 6 to 9 of surface elements 6.1 . 6.2 . 7.1 . 7.2 . 8.1 . 8.2 . 9.1 . 9.2 preferably electrically interconnected in each case in a so-called measuring bridge.

Safety devices are known, which operating parameters of the restraint devices, for example a restraining force of a safety belt or a size and a degree of inflation of an airbag, depending on a size and / or or a mass of the vehicle occupant I to adjust. For this purpose, the knowledge of the size and / or mass of the vehicle occupant I is required.

Also, the detection of the mass of the vehicle occupant I is possible by means of the device in a simple manner. The seat cushion upholstery foam part 4 and the seat back upholstery foam part 5 each characterized by a defined spring constant, due to which when subjected to the foam padding parts 4 . 5 with a defined mass a defined compression and thus a defined change in the distance between the respective surface elements 6.1 / 6.2 . 7.1 / 7.2 . 8.1 / 8.2 and 9.1 / 9.2 respectively. Based on the correlated with the change of the distance determined change in the electrical voltage between the respective associated surface elements 6.1 / 6.2 . 7.1 / 7.2 . 8.1 / 8.2 and 9.1 / 9.2 is the mass of the vehicle occupant I determined.

Also, when using multiple pairs of surfaces 6 . 7 . 8th . 9 so-called seat print images B can be generated. The resolution of the seat print images increases with the number of surface pairs. Such a seat pressure image B of the seat cushion pad member 2 shows 3 , To produce such a seat pressure image B are the surface pairs 6 and 7 from the surface elements 6.1 / 6.2 and 7.1 / 7.2 especially in the areas of the seat cushion pad foam part 4 the seat cushion cushion element 2 arranged in which the ischial tuberosity of the vehicle occupant I and whose thigh pad are located.

The illustrated seat pressure image B can be generated from the detected values of the electrical capacitance or voltage at the corresponding positions via a known evaluation algorithm, which on the one hand shows areas A1 to A6 in which, due to the mass of the seated vehicle occupant I Pressure on the seat cushion upholstery foam part 4 the seat cushion cushion element 2 and, on the other hand, how big this pressure is.

A first region A1 and a second region A2 thereby represent the determined pressure of the ischial tuberosity of the vehicle occupant I and a rear part of the thigh pad on the cushion pad foam part 4 A third area A3 and a fourth area A4 constitute a front part of the thigh pad on the pad cushion foam part 4 and a fifth area A5 and a sixth area A6 a rear side part of the thigh pad on a side pad of the seat cushion pad member 2 represents.

This seat pressure image B is used on the one hand, a sitting position of the vehicle occupant I to determine and to control the safety devices according to the determined seating position such that the greatest possible safety for the vehicle occupants I is achieved.

The seat print image B is on the other hand usable to the vehicle occupant I in the case of a "wrong" seating position, it is recommended to change this incorrect seating position. For this purpose, the seat print image B is optically output by means of a driver information system located inside the vehicle, in particular a display unit, for example a central display, wherein the recommendations for changing the seating position are made visually, acoustically and / or haptically.

Analogous to the illustrated seat pressure image B of the seat cushion upholstery element 2 is in a manner not shown additionally a seat pressure image of the seat back cushion element 3 generated, which also for determining the seating position of the vehicle occupant I and to operate the safety devices and to issue recommendations to the vehicle occupants.

The seat pressure distribution determined according to the invention can also be compared iteratively with a desired distribution of the seat pressure via an evaluation algorithm and the result used in iterative steps one or more of the seat adjustment variables seat longitudinal position, seat tilt, seat height, seat depth, seat width, backrest inclination, backrest width, lordosis depth and lumbar height to change until the measured seat pressure distribution coincides with the desired distribution.

LIST OF REFERENCE NUMBERS

1

vehicle seat

2

Seat cushion pad member

3

Seat back cushion element

4

Seat cushion cushion foam part

5

Seat back cushion foam part

6

first surface pair

6.1

first surface element of the first surface pair

6.2

second surface element of the first surface pair

7

second surface pair

7.1

first surface element of the second surface pair

7.2

second surface element of the second surface pair

8th

third surface pair

8.1

first surface element of the third surface pair

8.2

second surface element of the third surface pair

9

fourth surface pair

9.1

first surface element of the fourth surface pair

9.2

second surface element of the fourth surface pair

A1

first area

A2

second area

A3

third area

A4

fourth area

A5

fifth range

A6

sixth area

B

Seat print image

I

passenger

X

Seat direction

Y

lean toward

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

• EP 1211143 B1 [0004]
• EP 1731378 B1 [0007]
• WO 2009/059768 A1 [0008]

Claims (10)

Device for detecting a seat occupancy of a vehicle seat ( 1 ) comprising at least one cushioning element ( 2 . 3 ) coated with at least one coating ( 6.1 . 6.2 . 7.1 . 7.2 . 8.1 . 8.2 . 9.1 . 9.2 ) and an evaluation electronics, the one due to the weight of a vehicle occupant ( I ) produced change of at least one coating ( 6.1 . 6.2 . 7.1 . 7.2 . 8.1 . 8.2 . 9.1 . 9.2 ), in particular its change of position in the vehicle seat ( 1 ), detected. Device according to claim 1, characterized in that the at least one coating ( 6.1 . 6.2 . 7.1 . 7.2 . 8.1 . 8.2 . 9.1 . 9.2 ) on a padded foam part ( 4 . 5 ) of the at least one padding element ( 2 . 3 ) is applied. Device according to claim 2, characterized in that at least one upholstery foam part ( 4 . 5 ) two coatings ( 6.1 . 6.2 . 7.1 . 7.2 . 8.1 . 8.2 . 9.1 . 9.2 ) having a first surface element ( 6.1 . 7.1 . 8.1 . 9.1 ) and a second surface element ( 6.2 . 7.2 . 8.2 . 9.2 ) whose relative position is detected relative to one another and which together each comprise a surface pair ( 6 . 7 . 8th . 9 ) form. Device according to claim 3, characterized in that at least one padding foam part ( 4 . 5 ) at least two pairs of surfaces ( 6 . 7 . 8th . 9 ) and the evaluation electronics from the change of the respective relative positions between the first surface elements ( 6.1 . 7.1 . 8.1 . 9.1 ) and the second surface elements ( 6.2 . 7.2 . 8.2 . 9.2 ) of at least two pairs of surfaces ( 6 . 7 . 8th . 9 ) a seat pressure distribution of the associated padding element ( 2 . 3 ). Device according to one of claims 1 to 4, characterized in that the coatings ( 6.1 . 6.2 . 7.1 . 7.2 . 8.1 . 8.2 . 9.1 . 9.2 ) are electrically conductive. Device according to claim 5, characterized in that at least two of the coatings ( 6.1 . 6.2 . 7.1 . 7.2 . 8.1 . 8.2 . 9.1 . 9.2 ) form a capacitive distance sensor. Method for detecting a seat occupancy of a vehicle seat ( 1 ), characterized in that by the weight of the vehicle occupant ( I ) compression of at least one coating ( 6.1 . 6.2 . 7.1 . 7.2 . 8.1 . 8.2 . 9.1 . 9.2 ) comprehensive padding element ( 2 . 3 ), in particular one which has at least one coating ( 6.1 . 6.2 . 7.1 . 7.2 . 8.1 . 8.2 . 9.1 . 9.2 ) comprising upholstery foam part ( 4 . 5 ), is sensed. A method according to claim 7, characterized in that the distance between two opposite in the compression direction coatings ( 6.1 . 6.2 . 7.1 . 7.2 . 8.1 . 8.2 . 9.1 . 9.2 ) is sensed. Method according to claim 8, characterized in that the coatings ( 6.1 . 6.2 . 7.1 . 7.2 . 8.1 . 8.2 . 9.1 . 9.2 ) are electrically conductive and a change in at least one electrical variable of at least one coating ( 6.1 . 6.2 . 7.1 . 7.2 . 8.1 . 8.2 . 9.1 . 9.2 ) is measured and evaluated. Vehicle seat ( 1 ), comprising a device according to one of claims 1 to 6.

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