DE19847603A1 - Arrangement for weight sensing on motor vehicle seat arrangement has weight sensor(s) mounted between upper seat and lower seat parts and offset with respect to pivot axis between upper and lower parts - Google Patents

Abstract

The invention relates to a device for weight sensing on a vehicle seat arrangement, which has a vehicle seat (1) with a seat part (2) and a backrest part (3) fastened to the vehicle body (6) via a seat holder (5). The device further comprises a weight sensor with a downstream evaluation device. According to the invention, the seat part (2) has a seat lower part (8) and a seat upper part (7), the seat lower part (8) being fastened to the body (6) via the seat holder (5) and the seat upper part (7) being a seat cushion with a front seat ramp (22) carries. The upper seat part (7) is pivotally connected to the lower seat part (8) via a pivot axis (9) running in the transverse direction of the vehicle, while between the lower seat part (8) and the upper seat part (7) the at least one weight sensor (10, 12) is offset to the pivot axis ( 9) is attached. Further embodiments of the invention are claimed in the application documents.

Description

The invention relates to a device for weight sensing on a Vehicle seat arrangement according to the preamble of claim 1.

This device includes one on the vehicle body via a seat bracket attached vehicle seat with a seat part and a backrest part and at least one Weight sensor with downstream evaluation device.

The weight that a seat user exerts on the vehicle seat becomes in itself known manner for influencing an associated with the vehicle seat Security device detected.

For this purpose, simple seat occupancy detections with switching signals are known, which when occupied Seat an associated safety device, such as a restraint gas cushion and / or Switch the belt tensioner activatable or an activation when the vehicle seat is free exclude. For example, there is a device for detecting seat occupancy for a vehicle seat known (DE 94 16 933 U1), in which the weight by a Seat occupancy leads to an elastic deformation of a deformable body, wherein a Transducer forms an electrical switching signal from this deformation. In another The seat support forces are a device for detecting a seat occupancy spring-loaded seat occupancy switch supported (EP 0 670 239 A1) being by a Seat occupancy overrides the spring and the seat occupancy switch is closed.

Safety devices are also known, the effect of which is targeted and metered in Dependence of the weight and / or a position of a seat user is controllable. In particular, this can influence the inflation behavior of an inflatable restraint cushion to be influenced. For example, a safety device with a Knock-up element known (DE 40 02 448 A1), in which weight and position dependent the knee support element can be extended. The weight is measured by a weight sensor  determined between the vehicle floor and the vehicle seat. The position is about the Longitudinal adjustment of the vehicle seat detected.

In another safety device with a control device for influencing the Inflation behavior of a restraint cushion depending on the weight of a seat user is its weight by weight sensors in the seat cushion in conjunction with a Inclination sensor for the backrest of the vehicle seat detected (DE 44 42 841 A1). At strongly inclined backrest already supports part of the weight of the seat user so that the weight detected by the weight sensors in the seat cushion is too low and enlarged to the actual weight of the seat user according to the seat inclination becomes. Load cells are generally known as weight sensors, for example Strain gauge assemblies included. They are also inductive and capacitive Weight sensors in connection with vehicle seats are known (EP 0 796 768 A1).

A safety system with an inflatable restraint cushion is also known (DE 38 09 074 A1), which can be filled completely or only partially via a control circuit. With a seat user shifted relatively far forward in the direction of travel, one Activation of the safety system only partially unfolded the restraint cushion, while at a full inflation occurs in a normal sitting position. These different Positions are determined by weight or Pressure sensors determined on each slide rail of a longitudinally adjustable vehicle seat, by evaluating the pressure forces acting differently on these sensors.

Furthermore, safety devices are known in which the front edge of a vehicle seat can be raised as a seat ramp in the event of a vehicle impact by means of a lifting mechanism:
For such a seat ramp adjustment, an air bag is known which can be inflated by a gas generator (DE 197 35 915 A1). In a similar arrangement, an inflatable air bag is used to bulge a hump on the seat ramp (DE 195 04 975 A1). It is also known to bulge only a central part of a seat ramp using an airbag (DE 196 00 278 C1).

The drive for an accident-related seat ramp adjustment is also an electropneumatic one acting cylinder piston arrangement known (DE 195 29 031 A1). It is also known that  Drive for seat ramp adjustment from relative movements caused by accidents Derive vehicle parts, for example between a vehicle seat and a Drive unit (DE 33 37 232 A1) or a relative movement of a vehicle seat compared to a body-fixed slide rail (EP 0 552 160 B1).

The object of the invention is a functional and easy to produce To propose a device for weight sensing on a vehicle seat arrangement, which can be used for other functions or can be combined with other devices.

This object is achieved with the features of claim 1, claim 9 and Claim 17 solved.

According to claim 1, the seat part consists of a seat bottom as a fixed seat frame or as a fixed seat shell and from a seat top as a fixed seat frame or as a fixed seat shell. The seat bottom is via a seat bracket on the body attached. The upper part of the seat carries a seat cushion with a front seat ramp. The seat top is with the seat bottom over a swivel axis running in the transverse direction of the vehicle pivotally connected. There is at least one between the seat bottom and the seat top Weight sensor attached to the swivel axis, causing the upper part of the seat to overlap supports the weight sensor on the seat bottom.

It is advantageously achieved that the weight of a seat user only over the Contact forces of the seat upper part on the seat lower part is measured, resulting in such Measurement largely independent of otherwise disturbing and distorting measurements Boundary conditions, such as influences of a seat cushion upholstery Seat cushion foam, a seat cover, the temperature of disturbing forces acting on the backrest act, and the sitting position can be maintained. So that is such weight sensing easy and inexpensive to manufacture and delivers with one or only a few Weight sensors easily usable measurement results.

When the pivot axis is arranged between the upper part of the seat and the lower part of the seat in a rear seating area swivels the upper part of the seat out of it Normal position for raising or lowering the front seat ramp. A such, in an accident favorable seat ramp adjustment can be done easily with the help of a pyrotechnic, power-limited drive between the upper and lower parts of the seat  be carried out, in the event of a front impact the front seat ramp can be raised and at in the event of a rear-end collision, the seat ramp can be lowered. This arrangement results in this arrangement a favorable combination of the above Weight sensing with a seat ramp adjustment. The o. g. Weight sensing is independent of an additional device for one Seat longitudinal adjustment and / or seat height adjustment, so that such devices in themselves are known to be used.

In a further development, sliders on the lower part of the seat engage for a longitudinal adjustment of the seat or castors in seat rails, each on another, offset Weight sensors are mounted on the vehicle body. So that for a improved weight sensing, for example axial forces in the bearings and Inclination loads of the vehicle seat can be detected, which also in an evaluation Statements about a seat user's current seating position result. In addition, the vehicle-related center of gravity of the occupant are determined, d. H. the distance of the Airbag occupants are known. This allows security systems in particular Effect can be adapted to different weights and seating positions.

A seat height adjustment is easy with a two-part seat bottom by displacement both parts on assigned inclined surfaces preferably by means of an electrical Drive feasible.

Known load cells are advantageously used as weight sensors usually include strain gauge assemblies. Depending on the Other, generally known pressure and force transducers are also used be working, for example, piezoelectric, inductive, capacitive or via light guides.

In one embodiment, the backrest part is connected directly to the seat bottom part, so that only the weight on the seat of the pivoted seat top is detected.

Alternatively, the backrest part can be connected to the pivotably seated upper part be, the pivot axis, if necessary, at the same time the backrest pivot axis and Seat top pivot axis can be. This is particularly advantageous for a rear impact, because then the whole unit from the upper part of the seat and the backrest part downwards or forwards can be pivoted.  

According to claim 9, the object of the invention is achieved in that as Weight sensor at least one pressure sensor filled with pressure media, with at least a movable wall bounded pressure space is provided, on the movable Wall at least one seat part element for transferring a weight to the pressure medium is supported, the pressure chamber being connected to a pressure sensor. Preferably a liquid is used as the pressure medium. Depending on the circumstances, too Gas can be used as a pressure medium. This allows the pressure transducer to be used independently of connected pressure sensor in its geometric dimension to the requirements of Weight sensing can be adjusted on a vehicle seat. In addition, such can be relative large-volume pressure transducers may be used to improve comfort, in which in connection with the weight sensing damping properties of the Pressure transducers.

In preferred embodiments, the pressure spaces of such pressure sensors can be used as Cylinder volume of cylinder piston units or as the interior of pressure hoses be executed. In particular, this is a favorable weight sensor on one Tripod seat possible: This is a seat shell and / or a seat frame with a first Pressure transducer supported as a peripheral pressure hose that connects to one Pressure sensor preferably with one end at one chambers Two-chamber pressure sensor is connected. This takes place in the middle, front area Support via a second pressure sensor, which is designed as a cylinder piston unit is. The support can here, if necessary, also with the interposition of the first Pressure transducer, d. H. of the pressure hose running around the edge. Another The seat shell and / or the seat part frame is supported in the rear area via a U-shaped pressure hose, the U-leg in the seat rail can be integrated, or via a circumferential pressure hose. With one Arrangement can be made by the connected pressure sensors Single print information and the combination of this print information about one suitable algorithm, adapted to an individual vehicle seat, the weights of Seat users are determined with high accuracy, with disturbances being filtered out. If necessary, the information obtained can also be used to draw conclusions about the current seating positions of a seat user can be reached.

In a preferred embodiment, parts of the pressure hose can be in one be attached to the body-fixed rail profile of the longitudinal adjustment by a seat rails floating on them are supported, supported on the seat casters  are. This is independent of the respective longitudinal adjustment position of the vehicle seat appropriate weight sensing possible. To avoid friction between the Floating seat rail and the rail profile is used as a seat rail U-profile proposed with concave U-legs.

Furthermore, the object of the invention is achieved with the features of claim 17. For this purpose, at least one weight sensor is provided on the seat part and / or on the seat holder Frequency and / or amplitude measurement of seat surface forces and / or seat support forces arranged. The sensor signals are fed to an evaluation unit, which also has an Control and / or regulating device is connected downstream. Next are controllable Damping devices arranged directly on the seat part and / or on the seat bracket, which in Dependency of a predetermined algorithm of the frequency and / or determined Amplitude values for controllable seating comfort are controllable Seat movements and constraining forces on a seat user are therefore for one Comfort improvement can be influenced.

Known, controllable damper elements can be used as damping devices be used. As controllable damper devices can also be used directly elastic bearing elements are used, the identification of which is controllable. Preferably For this purpose, inductive sensors can be integrated in rubber elements, which can be used for both Weight sensing and control of the damping can be used.

The invention is explained in more detail with reference to a drawing.

Show it:

Fig. 1 is a schematic side view of a vehicle seat with a Gewichtssensierung and a seat ramp adjustment,

Fig. 1a and 1b, each a variant of FIG. 1,

Fig. 2 is a schematic side view of a second embodiment of a vehicle seat with Gewichtssensierung,

Fig. 3 a section through a pressure transducer along the line AA of Fig. 2,

Fig. 4 shows a section through two pressure transducers along the line BB of Fig. 2,

Fig. 5 shows a section through a seat rail with a pressure sensor along the line CC of Fig. 2,

Fig. 6 is a schematic front view of a third embodiment of a vehicle seat with weight sensing, and

Fig. 7 is a schematic side view of a vehicle seat with Gewichtssensierung similar to the embodiment according to Fig. 6.

In Fig. 1 a side view of a vehicle seat 1 is shown schematically, and of a backrest part 3 with headrest 4 comprises a seat part 2. The seat part 2 is connected to the vehicle body 6 via a seat holder 5 .

In particular, the seat part 2 consists of an upper seat part as a fixed upper seat shell 7 and a two-part lower seat part 8 .

The upper seat part as the upper seat shell 7 is connected to the lower seat part 8 via a pivot axis 9 lying in the rear seat area and extending in the transverse direction of the seat. The pivot axis 9 is supported by a first weight sensor as a first load cell 10 on the seat bottom 8 .

The upper seat shell 7 is supported in the front area by a pyrotechnic drive 11 and a second load cell 12 on the lower seat part 8 . In the first variant according to FIG. 1, the backrest part 4 is connected directly to the lower seat part 8 via supports, so that only the weight on the upper seat shell is detected by the weight sensors 10 and 12 .

The two-part lower seat part 8 consists of a lower inclined part 13 and an upper inclined part 14 , which are slidably abutting against one another on an inclined surface. With a relative adjustment of the inclined parts 13 , 14, a seat height adjustment is possible by means of an electric drive 16 (indicated by dashed lines).

On the lower inclined part 13 , seat rollers 17 , 18 are attached on both sides, which slidably engage in seat rails 19 arranged on both sides for longitudinal adjustment. The principle of weight sensing also works with a parallel rail seat without castors.

The seat rails 19 are supported by further weight sensors as load cells 20 , 21 with respect to the body 6 . The arrangement according to FIG. 1 has the following function:
in normal operation, the load cells 10 , 12 , 20 , 21 support and / or axle forces are measured, which, with a suitable evaluation using an algorithm, enable the weight and, if necessary, a sitting position of a seat user to be recorded. In the event of a front impact of the vehicle determined by an accident sensor, the pyrotechnic drive 11 is activated such that the seat ramp 22 is raised. In contrast, when a rear-end collision is determined, the seat ramp 22 is lowered or, in the variants described below, the entire seat is tilted forward in accordance with FIGS. 1a and 1b. The seat ramp lift is also force-limited.

In the second variant according to FIG. 1a, the backrest part 3 is connected to the upper seat part 7 , so that, in particular in the event of a rear-end collision, the entire unit comprising the backrest part 3 and the upper seat part 7 is pivoted downwards or forwards. In a similar third variant according to FIG. 1b, the pivot axis 9 is at the same time the backrest pivot axis and the upper part of the pivot axis.

FIG. 2 shows a second embodiment of a vehicle seat 23 in a schematic side view, FIGS. 3 to 5 showing sections corresponding to the section lines shown. The vehicle seat 23 is a tripod seat with two lateral, rear supports and a central, front support of a seat part 24 .

The seat part 24 is supported in relation to a seat part frame (not shown in more detail) or a fixed seat part shell with a first pressure sensor in the manner of a pressure hose 25 running around the edge ( FIG. 3), which is connected at one end to a pressure sensor or to chambers of a two-chamber pressure sensor 26 .

The vehicle seat 23 is supported in the front, middle area by a second pressure sensor, which is designed as a cylinder piston unit 27 and is connected to a pressure sensor 28 ( FIG. 4). The piston can also be used to raise the seat ramp in the event of a front impact and to lower it in the event of a rear impact.

In the rear area, the vehicle seat 23 is supported on seat rails 29 via a third pressure sensor, which is designed as a U-shaped pressure hose 30 , the pressure hose 30 being connected to a two-chamber pressure sensor 31 with one side in each case. From the corresponding enlarged sectional view of FIG. 5 it can be seen that in a body-fixed C-rail profile 32 in the lower part the U-legs of the pressure hose 30 are contained, whereupon a U-shaped seat rail 33 is held, which holds the pressure hose 30 in each case spreads. The U-legs of the seat rail 33 are drawn in concavely to reduce contact friction in the C-rail profile 32 . The center of gravity of the occupant in the Y direction can be determined with the U-shaped sensor.

The pressure hoses 25 , 30 and the cylinder piston unit 27 are filled with liquid and represent pressure transducers that are well suited for weight sensing. From the measured pressure distributions and the information from the pressure sensors 26 , 28 , 31 , the weight of a seat user as well as his or her current sitting position can be determined by a suitable algorithm, whereby disturbance variables can be filtered out.

FIG. 6 shows a third embodiment of a vehicle seat 34 in a schematic front view, FIG. 7 showing a similar seat design in a side view.

Also in the embodiment according to FIGS. 6 and 7, a seat part 35 or a stable substructure of the seat part is supported against a seat frame 39 by weight sensors 36 , 37 , 38 .

Several sensor variants are shown here as weight sensors, which can be arranged in different combinations if necessary: In the seat part, a pressure-sensitive film 46 and a liquid-filled cushion 47 with a pressure sensor 48 are attached. The seat part 35 is supported by sensors 37 , 38 , which can also be designed as circumferential pressure hoses in the manner described above. In addition, seat rails with sensors 41 , 43 and possibly without sensors are shown. The vehicle seat can be designed as a tripod or four-legged seat.

Seat rollers 40 are attached to the seat frame 39 , which run in a seat rail and which in turn are supported by weight sensors 41 , 42 , 43 . In Fig. 7, the acting weight forces are shown with arrows 44 and in Fig. 6 with arrows 45 the corresponding counter-support forces on the weight sensors.

With the arrangement of weight sensors 36 to 38 and 41 to 43 shown here, it is in turn possible for a seat user to record the weight while eliminating disturbance variables and possibly in conjunction with a position determination.

The weight sensors are here as elastic bearing elements in the manner of Rubber elements executed in the inductive transducer (not shown in detail) are integrated. Via these inductive sensors or, if necessary, through additional controllable ones Damping devices are the bearing identifications depending on the inductive Transducer ascertained, road-excited frequency and amplitude values for Controllable seat comfort improvement.  

Reference list

1

Vehicle seat

2nd

Seat part

3rd

Backrest part

4th

headrest

5

Seat bracket

6

body

7

Seat shell

8th

Lower part of the seat

9

Swivel axis

10th

1. Load cell

11

pyrotechnic drive

12th

2. Load cell

13

lower sloping part

14

upper sloping part

15

Sloping surface

16

Electric drive

17th

Seat castor

18th

Seat castor

19th

Seat rails

20th

Load cell

21

Load cell

22

Seat ramp

23

Vehicle seat

24th

Seat part

25th

first pressure sensor, pressure hose

26

Dual chamber pressure sensor

27

Cylinder / piston unit, second pressure sensor

28

Pressure sensor

29

Seat rail support

30th

pressure hose

31

Dual chamber pressure sensor

32

Rail profile

33

Seat rail

34

Vehicle seat

35

Seat part

36

Weight sensor

37

Weight sensor

38

Weight sensor

39

Seat frame

40

Seat casters

41

Weight sensor

42

Weight sensor

43

Weight sensor

44

arrow

45

arrow

46

pressure sensitive film

47

pillow

48

Pressure sensor

Claims (21)

1. Device for weight sensing on a vehicle seat arrangement, with a vehicle seat ( 1 ) attached to the vehicle body ( 6 ) via a seat holder ( 5 ) with a seat part ( 2 ) and a backrest part ( 3 ), and with at least one weight sensor with a downstream evaluation device,
characterized by
that the seat part ( 2 ) has a seat lower part ( 8 ) as a fixed seat subframe or as a fixed seat lower shell and a seat upper part ( 7 ) as a fixed seat upper frame or as a fixed seat upper shell, the seat lower part ( 8 ) via the seat holder ( 5 ) on the body ( 6 ) is attached and the upper seat part ( 7 ) carries a seat cushion with a front seat ramp ( 22 ),
that the upper seat part ( 7 ) is pivotally connected to the lower seat part ( 8 ) via a pivot axis ( 9 ) extending in the transverse direction of the vehicle, and
that between the lower seat part ( 8 ) and the upper seat part ( 7 ) the at least one weight sensor ( 10 , 12 ) is mounted offset to the pivot axis ( 9 ). 2. Device according to claim 1, characterized in that
that the pivot axis ( 9 ) lies in a rear seating area,
that in a front impact determined by an accident sensor by swiveling up the seat part ( 7 ) from its normal position, the front seat ramp ( 22 ) can be raised and, in the event of a rear impact, the seat ramp ( 22 ) can be lowered, and
that is arranged as a pivoting drive is a pyrotechnic drive (11) effective in a front impact force limiter between the seat shell (7) and seat base (8), wherein the swivel drive (11) and the pivot axis are each supported by weight sensors (10, 12). 3. Device according to claim 1 or claim 2, characterized in that
that the seat bracket ( 5 ) for fastening the seat bottom part ( 8 ) to the vehicle body ( 6 ) consists of at least two seat rails ( 19 ) connected to the vehicle body ( 6 ), engage in the seat bottom part sliders and / or rollers ( 17 , 18 ) in a longitudinally adjustable manner , and
that the seat rails ( 19 ) are mounted on offset weight sensors ( 20 , 21 ) on the vehicle body ( 6 ). 4. Device according to one of claims 1 to 3, characterized in that the lower seat part ( 8 ) is formed in two parts with mutually on associated inclined surfaces ( 15 ) displaceable seat lower parts ( 8 ) which are preferably displaceable for an adjustment of the seat height by an electric drive ( 16 ) are. 5. Device according to one of claims 1 to 4, characterized in that load cells ( 10 , 12 , 20 , 21 ) are used as weight sensors. 6. Device according to one of claims 1 to 5, characterized in that the backrest part ( 3 ) is connected directly on both sides of the upper seat part ( 7 ) to the lower seat part ( 8 ), so that only the weight on the seat surface of the upper seat part ( 7 ) is detected becomes. 7. Device according to one of claims 1 to 5, characterized in that the backrest part ( 3 ) is connected to the pivotably seated upper part ( 7 ), so that in particular in the event of a rear-end collision, the entire unit comprising the backrest part ( 3 ) and the upper part ( 7 ) is pivotable downwards / forwards. 8. Device according to one of claims 1 to 5, characterized in that the pivot axis ( 9 ) is simultaneously the backrest pivot axis and the upper part pivot axis. 9. Device for weight sensing on a vehicle seat arrangement, with a vehicle seat ( 23 ) fastened to the vehicle body via a seat holder, with a seat part ( 24 ) and a backrest part, and with at least one weight sensor and downstream evaluation electronics, in particular according to one of claims 1 to 8, thereby characterized in that at least one pressure transducer ( 28 ) is provided as the weight sensor as a pressure chamber filled with pressure and bounded by at least one movable wall, on the movable wall of which at least one seat part element is supported for transmitting a weight to the pressure medium, the pressure chamber being connected to a pressure sensor. 10. The device according to claim 9, characterized in that as a printing medium Liquid is used. 11. The device according to claim 9 or claim 10, characterized in that as Pressure chamber a cylinder volume of a cylinder-piston unit and / or Pressure hose is used. 12. The apparatus according to claim 11, characterized in that a seat shell and / or a seat frame with a first pressure sensor ( 25 ) is supported as a peripheral pressure hose, which preferably has one end to a pressure sensor, preferably a two-chamber pressure sensor ( 26 ) connected. 13. The apparatus according to claim 11 or claim 12, characterized in that a seat shell and / or a seat frame in the front region, preferably at a central point as a support for a tripod seat with a second pressure sensor ( 27 ) is supported, the second pressure sensor ( 27 ) is preferably designed as a cylinder-piston unit, optionally as a pyrotechnic piston with an approximately vertical orientation. 14. Device according to one of claims 11 to 13, characterized in that a seat shell and / or a seat frame in the rear region is preferably supported at two laterally opposite points with a third pressure sensor via a U-shaped pressure hose ( 30 ), the U -Legs aligned parallel to the vehicle longitudinal axis and are part of a seat rail support ( 29 ) and in the U-base a pressure sensor, preferably a two-chamber pressure sensor ( 31 ) is arranged and connected. 15. The apparatus according to claim 14, characterized in that in a body-fixed rail profile at least part of a pressure hose ( 30 ) is contained, which is overlapped by a floating seat rail ( 33 ), seat rollers of a longitudinally adjustable vehicle seat ( 23 ) in the rail profile ( 32 ) run on the surface of the seat rail ( 33 ). 16. The apparatus according to claim 14, characterized in that the seat rail ( 33 ) in cross section has a U-profile with concavely drawn-in U-legs. 17. Device for weight sensing on a vehicle seat arrangement,
with a vehicle seat ( 34 ) fastened to the vehicle body via a seat holder as a three-leg seat or four-leg seat, with a seat part ( 35 ) and a backrest part, and
with at least one weight sensor with downstream evaluation electronics, in particular according to one of claims 1 to 16, characterized in that
that at least one weight sensor ( 36 , 37 , 38 , 41 , 42 , 43 ) for frequency and / or amplitude measurement of seat surface forces and / or seat support forces is arranged on the seat part ( 35 ) and / or on the seat holder,
that the sensor signals are fed to an evaluation unit, which is followed by a control and / or regulating device,
that controllable damping devices are arranged on the seat part and / or on the seat holder, which are connected to the control and / or regulating device and can be controlled as a function of an algorithm which can be specified there, preferably as a function of the determined frequency and / or the amplitude values for improving the seating comfort. 18. The apparatus according to claim 17, characterized in that a pressure-sensitive foil (46) and / or a liquid-filled cushion (47) are arranged with a pressure sensor (48) as weight sensors in the seat part (35) and the seat part (35) via sensors ( 37 , 38 ) and / or the entire seat is supported on seat rails with sensors ( 41 , 43 ). 19. The apparatus according to claim 17 or claim 18, characterized in that as controllable damping devices separate damper elements are used. 20. Device according to one of claims 17 to 19, characterized in that as controllable damper devices are used elastic bearing elements, the Identifier is controllable.   21. The apparatus according to claim 20, characterized in that in rubber elements inductive transducers are integrated.