This application claims the priority of German application 196 51 670.6-14 filed in Germany on Dec. 12, 1996, the disclosure of which is expressly incorporated by reference herein.
The invention relates to an arrangement for adjusting the sitting position of a vehicle occupant relative to the seat, which has a seat part with a seat cushion, a backrest which is swivellably held on the back seat part and a headrest.
In the case of vehicle seats, it is known to provide a plurality of adjusting possibilities so that the vehicle occupant sitting down in the vehicle seat can assume any sitting position she or he desires. These possibilities include longitudinally displacing the vehicle seat, adjusting the height of the seat cushion, adjusting the angle of slope of the backrest with respect to the seat cushion, and adjusting the height of the headrest. In most cases, these adjustments can be carried out manually by the vehicle occupant using corresponding handwheels, or by using hand levers that are operated utilizing corresponding servo motors operated by hand switches.
For minimizing the danger of injury to the vehicle occupant, it is necessary in the case of certain seat components to prevent the vehicle occupant from carrying out the adjustment and implementing the adjustment automatically. This applies particularly to the adjustment of the headrest since only its precise adjustment ensures satisfactory support of the head in an accident, thus providing sufficient protection.
In the case of a known arrangement for automatically adjusting vehicle seat components (German Patent Document DE 34 27 466 C2), a sensor provided which senses the sitting height of the vehicle occupant placed in the vehicle seat by determining the occupant's head position or shoulder position. Corresponding to the measuring result, a control device causes an adjustment of the headrest and the belt deflection mounting of the seat belt fastened to the vehicle body to the height positions required for the sitting height. The adjustment of the headrest and the belt deflection mounting takes place by means of electric motors for the purpose of adjusting the headrest and the belt deflection. The headrest is vertically slidably held on the backrest and the deflection mounting is vertically slidably held on the B-column of the vehicle body.
In a first embodiment of the sensor, the sensor consists of a light transmitter arranged in the occupant compartment, where a reflecting surface fastened in the upper area of the front side of the headrest and a light receiver which is arranged in front of the vehicle occupant in the occupant compartment senses the light reflected by the reflection surface. The light transmitter and the light receiver are preferably housed in a common housing.
In an alternative embodiment of the invention, the sensor consists of an ultrasonic distance meter, which is arranged above the usual head position or shoulder position of the sitting vehicle occupant and which measures the distance to the head or to the shoulder of the vehicle occupant.
Studies have shown that, in the case of a rear impact onto the vehicle or when the head is jerked back after the vehicle sustains a frontal impact, the headrests offer the best protection for the vehicle occupants if, in particular, the cervical spine is sufficiently supported. It was attempted to achieve this by means of headrests, where in this case the head cushion is swivellable about an axis of rotation situated on top.
However, the effect is only optimal if the head cushion rests completely against the cervical spine. For the purpose of ensuring this, the head cushion rests completely against the cervical spine, and the height of the headrest must be adjusted in a precise manner. An increase in comfort is achieved by means of so-called active headrests, where in the event of a rear impact, the head cushion is automatically swivelled onto the cervical spine so that the head cushion does not constantly rest against the cervical spine. In addition, for such an active headrest to offer a full protection, it is required that the headrest is precisely adjusted relative to the vehicle occupant. This is to guard against, in the case of an incorrect adjustment, the effect of the fast swivelling operation of the head cushion that may create additional stress to the vehicle occupant.
In such cases, the above-described known arrangement for adjusting the headrest will not lead to an adjustment of the height which is precise enough for the individual application. This is because the top edge of the head or the shoulder edge, which is sensed by the sensor as a characteristic of the seating height of the vehicle occupant, cannot provide information concerning the precise position of the neck lordosis contour of a seated person.
It is an object of the invention to improve an arrangement for adjusting the sitting position of a vehicle occupant of the initially mentioned type, where a seat adjustment which is individually adapted to the sitting height of the vehicle occupant is possible with minimal effort required from the vehicle occupant. It is another objective of the invention to improve an arrangement for adjusting the sitting position of a vehicle occupant where, during each seat adjustment, a precise support of the cervical spine of the vehicle occupant which is individually adapted to the vehicle occupant is automatically ensured in an accident.
These objects are achieved according to preferred embodiments of the invention by providing an apparatus for adjusting the seating position of a vehicle occupant relative to the seat components of a vehicle seat, having: a seat part with a seat cushion, the seat cushion being adjustable to two extreme positions; a backrest swivellably connected to the seat part; a headrest connected to the backrest that can be adjusted in its height position relative to the seat cushion, the headrest further having a sensor which determines the sitting height of the vehicle occupant seated on the seat cushion, wherein the sensor measures the sitting height in a no-contact manner; a control unit connected with the sensor and having a headrest adjusting motor for the headrest, the headrest adjusting motor being connected to the control unit, a seat cushion adjusting motor for vertical adjustment of the seat cushion connected to the control unit, a computer for computing the required height position of the headrest using scanning signals generated by the sensor; and a control logic unit for adjusting the computed height position of the headrest, the control logic unit first causing a controlling of the seat cushion adjusting motor and then a controlling of the headrest adjusting motor; wherein the sensor scans the cervical spine of the vehicle occupant in order to determine the seating position of the vehicle occupant.
The arrangement according to the invention has the advantage in that the seat height adapted to the sitting height of the vehicle occupant is first adjusted automatically and then the headrest adjusted to an optimal height position relative to the seat height. From this optimal height adjustment due to the precise assignment of the head cushion to the individual contour of the neck lordosis of each vehicle occupant, maximum protection is ensured in the event of an accident. The motor vehicle seat equipped with the arrangement according to the invention requires reduced adjusting efforts from the vehicle occupant because the individual distance to the steering wheel and pedals is adapted only by longitudinal displacement of the seat and the slope adjustment of the backrest. This can be carried out manually and with relatively few if any problems.
According to a preferred embodiment of the invention, the seat cushion adjusting motor can be switched on and off manually. The control unit is constructed such that, after each manual switching-off of the seat cushion adjusting motor, the headrest adjusting motor is controlled by the control unit for readjusting the height of the headrest. By means of these constructive measures, an additional possibility is provided to the vehicle occupant for readjusting the seat height, and it is simultaneously ensured that an appropriate adjustment of the height position of the headrest occurs in the event of an accident.
In the case of a vehicle seat which is equipped with a restraining system activatable in the event of a crash, parts of the arrangement according to the invention are utilized for activating the restraining system. For this purpose, the control unit is activated in the event of a crash and, in turn, activates the sensor. Upon activation of the sensor, the computer determines from the measuring signals supplied by the sensor the and from the actual values of actual-value generators, which sense the longitudinal displacement position and the backrest slope of the vehicle seat, computes the distance of the vehicle occupant from the steering wheel or the dashboard. The control logic will then activate the restraining system according to specific requirements. That is, corresponding to the distance of the vehicle occupant from the air bag systems in the steering wheel and in the dashboard determined by the arrangement.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.