EP1361967A2

EP1361967A2 - Device for receiving a force actin upon a vehicle seat

Info

Publication number: EP1361967A2
Application number: EP02708162A
Authority: EP
Inventors: Andreas Aumer; Ulrich Deml; Manfred Frimberger; Karl-Heinz Eglseder
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2001-02-23
Filing date: 2002-01-25
Publication date: 2003-11-19
Also published as: JP2004517779A; WO2002066282A3; WO2002066282A2; US20040154843A1; KR20030077038A

Abstract

The invention relates to a device for receiving a force applied to a seat, particularly a vehicle seat. Said device comprises at least one spring element (5) for elastically positioning the seat in such a way that the seat support components (1,2,3,4) are coupled together by means of the spring element (5). The inventive device also comprises a sensor which detects the spring excursion or an alteration of the spring excursion or a position of the spring element.

Description

description

DEVICE FOR RECEIVING A FORCE IN A VEHICLE SEAT

The invention relates to a device for absorbing a force acting on a seat, in particular a vehicle seat.

In the field of occupant protection in motor vehicles, the determination of the occupant weight is becoming increasingly important. The occupant weight and possibly also the weight distribution over the vehicle seat are suitable parameters for determining an "out of position" of the occupant. With such an "out of position" attitude of the occupant, a complete inflation of the airbag can do more harm to the occupant than it does good. Such "out of position" cases occur when the occupant bends his head directly in front of the airbag outlet opening. In particular, small, light people are at risk because of their stature sit far in front of the steering wheel and may be at risk if the airbag is deployed suddenly. The determination of the occupant weight is usually necessary in conjunction with optical or other means for occupant position detection in order to determine whether one or more stages of a multi-stage airbag are to be activated. This minimizes the risk of injury to the occupant.

Mats to be introduced into the seat cushion and provided with electrical structures have been proposed which change their electrical resistance when subjected to weight.

The introduction of such a mat in a vehicle seat is extremely complex. The electrical connection of such a mat is also complex. DE 38 09 074 AI discloses a device in which pressure sensors attached to the seat support components carrying the seat cushion and the seat back indicate a change in weight. A front and a rear sensor, measuring pressure forces, is attached to each seat rail.

Strain gauges, capacitive or piezoelectric elements are generally used to absorb pressure changes.

A disadvantage of such a measuring device is that very small deformations on the existing seat structure must be detected by sensors. Path changes in the tens of μ range pose a problem with regard to the resolution of the measurement signal.

With regard to the use of the measuring device over the service life of the vehicle, the measuring arrangement must also be protected against overload. To do this, mechanical stops in the range of a few tens of μm would have to be produced in the known measuring device.

Geometric changes due to temperature influences have the same orders of magnitude as the measured variable in the known measuring device. The known measuring device therefore requires a device for compensating for such temperature influences.

All components used must have low tolerances. Components with these low mechanical tolerances are expensive.

The invention is therefore based on the object of specifying a device for absorbing a force acting on a seat, which ensures good resolution and is susceptible to faults. The invention is solved by the features of patent claim 1.

In this case, a spring element is additionally introduced into the existing seat support structure, which couples the seat support components to one another. The seat with seat cushion and seat back attached to the seat support structure is thus spring-loaded. A sensor is provided which records the spring travel of the spring element or a change in the spring travel or a position of the spring element.

Seat support components are essentially seat structures that support the seat with seat upholstery and backrest, in particular a base plate for the seat - in the case of a vehicle seat this is usually the bottom part of the body - seat rails for moving the seat that holds the seat with the seat rails connecting slides or seat struts that slide in the seat rails to hold the seat cushion or backrest.

In the case of the invention, the spring element is introduced into the force path “seat - seat rail - base plate” in such a way that it yields resiliently as soon as a force and in particular a weight force caused by an object or an occupant on the seat acts on the seat.

The spring element has a large spring travel and therefore delivers a significant signal. The weight as a force quantity is determined by measuring the spring travel / the deformation of the spring element. There is preferably proportionality between the quantities force and spring travel.

The spring element has a defined spring constant, so that a certain deformation of the spring element stands for a certain weight force acting on the spring element. The spring element is defined to be resilient when the weight load is transmitted via seat support components, and returns to its starting position when the weight load is ended.

Through use and suitable dimensioning, a spring travel is generated when the vehicle seat is loaded, which allows a very good resolution of the force quantity to be determined. A spring travel generated as a result of temperature change is negligible compared to a spring travel generated by the action of force.

Since the mechanical power = force x speed is large, a large electrical signal can also be expected. The mechanical structure is torque-free when the force to be measured is introduced and discharged. Therefore, mechanical tolerances of the interfaces (seat, seat suspension, chassis) have little or no influence.

Components do not require an extremely high tolerance accuracy, so that the device can be manufactured inexpensively. A standard sensor can also be used as a sensor for measuring the spring travel. The route measurement is technically possible and can also be industrialized.

Advantageous developments of the invention are characterized by the subclaims.

With maximum deflection of the spring element, the spring travel is preferably greater than or equal to 0.1 mm, in particular greater than or equal to 0.5 mm, and approximately 1 mm for a particularly good resolution.

In particular, the maximum deflection is less than 5 mm. With these size specifications for the maximum deflection of the spring element, the requirements with regard to a sufficient signal resolution on the one hand and a slight impairment of occupant comfort on the other hand are met. Too large a maximum deflection would result in the occupant feeling vibrating movements due to the spring element, which is not desired. Excessive maximum deflections also lead to a large overall height, which in turn can increase the interior dimensions. On the other hand, maximum deflections that are too low do not provide the required resolution in the measurement signal.

With a maximum deflection of the spring element of ± 1 mm, a distance traveled by the spring element of 1/100 mm can be resolved using commercially available sensors, which corresponds, for example, to a weight load of 1 kg with a spring constant of 10 ⁶ N / m. The weight can therefore be measured to the nearest kg.

The spring element with associated sensor can preferably be arranged between a seat rail and a base plate as seat support components. Then a spring element with an associated sensor is preferably provided at each support point between the seat rail and base plate, ie preferably 4 spring element / sensor arrangements at the ends of the seat rails between seat rail and base plate.

As a further development, the spring element with sensor can be arranged between the seat and the seat rail, again preferably in each support point, i.e. total 4

Spring element / sensor arrangements between seat and seat rail. Preferably, a spring element couples a carriage (3) which supports the seat and is displaceably mounted in the seat rail (2) with a seat strut (4), or else a first component of the carriage with a further component of the carriage. The invention and its developments are explained in more detail with reference to exemplary embodiments shown in the drawing. Show it:

Figure 1 shows a first embodiment of the invention in cross section. Fig. 2 shows another embodiment of the invention in cross section.

FIG. 1 shows a device for absorbing a force F acting on a seat.

Only a small section of a seat support structure is shown in cross section at one end of a seat rail 2. The seat rail 2 ends in FIG. 1 on the right-hand side and is coupled via a spring element 5 to a base plate 1, which in turn is shown only in one section in its longitudinal extent.

The spring element 5 is surrounded by a housing 6. The housing 6 is preferably a hollow profile body. The housing 6 protects the spring element 5 and in particular the sensor presented further below.

Bores 61 of the housing 6 allow a screw connection between the seat rail 2 and the spring element 5. A fastening screw 9 is guided through the bore 61. Two nuts 10 fix the seat rail 2 to the fastening screw 9, a further nut 10 and a stop 11 designed as a nut in turn fix the spring element 5 to the fastening screw 9.

In the exemplary embodiment, the spring element 5 is a steel spring in the form of a leaf spring, with several spring layers which can also be seen in FIG. 1. However, single-layer spring steel can also be used. Alternatively, other spring shapes can be used, such as a spiral spring.

At its ends, the spring element 5 is connected to the base plate 1 by fastening screws 7. When the device is used in a motor vehicle seat, the base plate is a component of the body, namely the vehicle floor.

When the spring element 5 is fastened to the base plate 1, spacers 8 are provided which, if appropriate together with housing components, hold the spring element 5 at a sufficient distance above the base plate 1 that the maximum desired or possible deflection of the spring element 5 in the direction of the base plate 1 is ensured is.

When the device is subjected to a force F, here, for example, a compressive force F in the direction of the base plate 1, the rigid coupling between the seat rail 2 and the spring element 5 also causes the latter to be in

Direction of arrow deflected down to base plate 1. The spring steel is the flexible spring element that allows deflections in the mm range, depending on the force acting on it in the direction of the arrow. Due to its edge-side clamping by the fastening screws 7, the spring element 5 is maximally deflected in its center. Reference number 51 denotes this location. In Figure 1, the spring element 5 is of course not subjected to any force and can be seen in its rest position.

At this location of the maximum deflection 51 with respect to the width of the spring element, a suitable sensor for determining the absolute position of the spring element 5, or for determining the spring travel covered, or for determining a change in spring travel is preferably also to be provided. The sensor can be based on different physical principles. It can be used: a Hall sensor, an LVDT cυ ω ot P> cn o Cn o cn O cn

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seemed transmitted. Due to the above-described resilient mounting of the seat rails with respect to the base plate / body, the spring elements are deflected. This deflection is measured with the associated sensors. By calculating the four sensor signals provided in this case, the force acting on the seat can be deduced, at least in the vertical direction.

If necessary, it is also possible to determine the force distribution on the vehicle seat. If, for example, a heavy object is placed on the front area of the seat, only the two spring elements arranged on the front ends of the seat rails are deflected in the direction of the base plate. The two spring elements arranged at the rear ends of the seat rails, on the other hand, are subjected to tension and deflected in the opposite direction. This sensor signal constellation allows conclusions to be drawn about the weight distribution on the vehicle seat.

In such a calculation of weight forces are as

Disturbances still to be calculated: The weight of the seat as well as the sled and rails themselves; short-term changes in force due to weight shift, etc.

Figure 2 shows a further embodiment of the invention in a cross-sectional view.

The same elements are identified by the same reference numerals as in FIG. 1.

Again, only a small section of a seat support structure is shown in cross-section at one end of a seat rail 2. The seat rail 2 ends on the right in FIG Seat rail 2 stored. The sled 3 is often referred to in the professional world as the seat shell. The seat rail 3 is attached to a base plate, not shown. The carriage 3 is coupled to a seat stay 4. The seat stay in turn carries the seat cushion and the rest of the seat structure. The coupling between the slide 3 and the seat strut 4 takes place via a spring element 5.

With regard to the properties of spring element 5, housing 6 and all other components of the resilient bearing, reference is made to the description of FIG. 1. According to FIG. 2, only the seat strut 4 is now connected to the spring element 5 instead of the seat rail 2 from FIG. 1, and the slide 3 is connected to the housing 6 instead of the base plate 1 from FIG.

According to FIG. 2, the spring element is therefore arranged at a different point in the force path within the seat support structure, but also reliably absorbs the weight force acting on the seat at this point.

For the use of the arrangement in a motor vehicle for determining a force acting on a vehicle seat, several of these arrangements according to FIG. 2 are preferably to be provided. At the left-hand end of the slide, which is not shown, a coupling of the seat strut with the same structure is also provided with the slide via a further spring element. The seat is thus resiliently mounted on the slide, with two support points at the ends of the slide. The other side of the slide, which engages in the further seat rail, is also provided with spring elements at its ends.

With regard to the determination of the force distribution and the calculation of weight sizes by extracting disturbance sizes, the explanations for FIG. 1 apply accordingly.

Claims

claims

1. Device for absorbing a force acting on a seat, in particular a vehicle seat, with at least one spring element (5) for resilient mounting of the seat such that seat support components (1, 2, 3, 4) are coupled to one another via the spring element (5) and with a sensor for recording the spring travel or a change in the spring travel or a position of the spring element.

2. Device according to claim 1, wherein the spring element (5) has a spring deflection of equal to or greater than 0.1 mm at maximum deflection.

3. Apparatus according to claim 1 or claim 2, wherein the spring element (5) has a spring travel of equal to or greater than 0.5 mm at maximum deflection.

4. Device according to one of the preceding claims, in which the spring element (5) at maximum deflection has a spring travel of equal to or greater than 1 mm.

5. Device according to one of the preceding claims, wherein the spring element (5) contains a steel spring.

6. Device according to one of the preceding claims, wherein the spring element (5) is designed as a leaf spring.

7. Device according to one of the preceding claims, wherein the spring element (5) is arranged in a housing (6).

8. Device according to one of the preceding claims, in which a stop (11) is provided which prevents deformation of the spring element (5) beyond a certain amount.

9. Device according to one of the preceding claims, wherein the spring element (5) is coupled to a seat rail (2), in which the seat is slidably mounted, and a base plate (1).

10. The device according to claim 9, wherein each seat rail associated with the seat (2) is coupled at its ends via a respective spring element (5) to the base plate (1).

11. The device according to claim 9 or claim 10, wherein the seat rail (2) on the spring element (5) and the housing (6) on the base plate (1) is fixed.

12. Device according to one of the preceding claims, in which the spring element (5) is coupled to a first component of a carriage (3) which supports the seat and is displaceably mounted in the seat rail (2) and to a second component of the carriage (3).

13. Device according to one of the preceding claims, in which the spring element (5) is coupled to a carriage (3) supporting the seat and displaceably mounted in the seat rail (2) and to a seat strut (4).