Abstract:
A sensor system for a crush protection device is disclosed. The system monitors an agitation of a vehicle part with a sensor. The sensor is arranged to detect an object being crushed between an active vehicle part and a body section or another vehicle part. The sensor has a layered formation. The sensor is applied on the active vehicle part and either or both of the body section of the vehicle and the additional vehicle part. Additionally, the sensor is adjusted to the shape of the active vehicle part and either or both of the body section and the additional vehicle part.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application claims priority to German patent application 20 2005 011 044.2 filed Jul. 6, 2004 which is herein incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     The present invention is directed to a sensor system for a crush protection device of a vehicle.  
         [0003]     Known sensor systems for crush protection devices at vehicles, particularly motor vehicles, are formed as contact banks, ultrasonic barriers or infrared barriers. The sensor systems as safety devices cooperate with the crush protection device so as to detect, for example, an object crushed between a vehicle part. The part may be for example a closing window pane and a body section. The cooperation is intended to stop the closing of the window pane and therefore prevent damage to the object, the window pane or the window lifter moving the window pane. Furthermore, touch sensors, for example piezoelectric or pyroelectric sensors, are used as sensors for crush protection devices. The piezoelectric of pyroelectric sensors may beset out as pressure sensors and in particular heat detectors so as to react to exercised pressure and in particular heat.  
       SUMMARY OF THE INVENTION  
       [0004]     An object of the present invention is to provide a sensor system for a crush protection device for the monitoring of a movement of a vehicle part such that a crushed object is safely detected. A further object is for the sensor system to be produced in a simple and cost-efficient way.  
         [0005]     These and other objects are solved by the present invention which provides a sensor system with the characteristics of claim  1 .  
         [0006]     According to the invention, the sensor of a sensor system is formed layered, applied on an active vehicle part, body section and/or additional vehicle part, and is adjusted to the shape of the active vehicle part, the body section and/or the additional vehicle part.  
         [0007]     The solution according to the invention therefore provides a sensor system for a crush protection device for the monitoring of the movement of a vehicle part. The sensor, of the sensor system, is arranged layer-shaped on the active vehicle part itself, the body section of a motor vehicle and/or an additional vehicle part. Accordingly, the sensor and therefore the sensor system are adjusted to the shape of their environment in such a way that they are unobtrusive from the outside and by its layer-shaped and shape-adjusted application cannot be recognized from the outside as a special component. The sensor is connected with the active vehicle part, the body section or the additional vehicle part in such a way that there are no special fixtures, as for example screw or plug connections, openings, indentations, recesses or such, Accordingly, the assembly work for applying the sensor is considerably reduced. A sensor is produced accordingly which, by way of its application, can be extended to areas of vehicles where the application of a sensor has so far been difficult or even impossible.  
         [0008]     In an embodiment of the present invention, the sensor is produced by a layer-shaped precipitation on the active vehicle part, the body section of a motor vehicle or the additional vehicle part. Thin layers, which cover the active vehicle part, the body section or the additional vehicle part at least partially, can be produced by the precipitation, by using suitable materials, and based by way of the layer-shaped application to adapt to the shaping of the surface of the active vehicle part, the body section or the additional vehicle part. The thin layers are further firmly connected with the body section or the vehicle part.  
         [0009]     The sensor can be arranged on the active vehicle part as well as on the body section or the additional vehicle part. The additional vehicle part can thereby be applied at the vehicle in another function and additionally serve as a carrier medium for the sensor. The sensor may be precipitated from a sealing element forming the additional vehicle part or paneling element allocated to the body. By the application of such a vehicle part, the handling of a big body part for the production of the sensor can be eliminated and the process necessary for the application of the sensor facilitated. The body part serving as a carrier medium can be fixated at the body together with the sensor allocated on the vehicle part and, according to use and kind of the part of the vehicle, glued, plugged, screwed or connected in a different way with the vehicle.  
         [0010]     The sensor system may be installed in such a way that that it already recognizes the approaching of an object to the active vehicle part, the body section or the additional vehicle part so as to timely avoid a possible crushing of an object. For this purpose, the sensor may be provided as layered precipitated antennas on the active vehicle part, the body section or the additional vehicle part, which are part of a sensor system and detect an approaching object.  
         [0011]     In another embodiment, the sensor detects a force of pressure exercised on the body section or one of the vehicle pieces, the force being potentially caused by an object being crushed between the active vehicle part and the body section or the additional vehicle part. Accordingly, the sensor of the sensor system is installed as a piezoelectric sensor which is applied layered on and partially covers the active vehicle part, the body section or the additional vehicle part. The piezoelectric sensor is subject to a force of pressure which is exercised by an object on the sensor. The sensor translates this force into an electrical signal which can be transmitted and evaluated thereby indicating an object.  
         [0012]     The piezoelectric sensor may comprise a piezoelectric layer and electrodes at least partially the covering piezoelectric layer. The piezoelectric sensor can be produced by the precipitation of suitable piezoelectric materials on the active vehicle part, the body section or the additional vehicle part. Tension, in a vertical direction towards the surface, is produced by the piezoelectric layer while being subject to a force of pressure vertical to the surface of the layer which can be measured by electrodes below and above the layer and induce a charge transfer and therefore an electrical signal. The piezoelectric sensor is formed with thin layers produced by precipitation. Accordingly, the piezoelectric sensor is almost invisible from the outside and does not disturb the visual design of the vehicle. Therefore, there are no special measurements necessary for the application of the sensor at the vehicle and the design and set-up of the body do not need to be modified.  
         [0013]     The piezoelectric layer of the sensor is at least partially covered with electrodes made from a conductive material, while using a sensor system with a piezoelectric sensor. Because the body normally comprises a metal and therefore a conductive material, it is possible to use the body section as one of the electrodes of the sensor and to apply the piezoelectric layer directly on to the conductive body. Similarly, the vehicle body, if it is conductive and if the sensor is applied on the vehicle part, can be used as an electrode for the sensor. It is an advantage of this embodiment that supply lines for the sensor could be omitted. In a further embodiment, it is also possible to separate the sensor by an isolating layer or be electrically isolated from the body section and to provide electrodes on both sides of the piezoelectric layer so that no electrodes lie on the mass potential of the body or the vehicle part by force.  
         [0014]     Additionally, the supply lines necessary for bonding with the sensor can be produced by applying suitable conductive materials on the body section or the vehicle section so as to avoid cables and to simplify the installation and assembly of the sensor and the crush protection device.  
         [0015]     It is possible that the electronic selection circuit necessary for the sensor is also produced directly on the active vehicle part, the body section or the additional vehicle part by precipitation of suitable materials together with the piezoelectric sensor. An additional simplification of the construction of the sensor can be reached, short line lengths can be produced between the piezoelectric sensor and the selection switch, and interferences can therefore be minimized.  
         [0016]     The sensor of the sensor system can be arranged on or below the coat of lacquer, as for example a seal. By a coat of lacquer covering the sensor, the sensor can be adjusted in colour with the environment to make the piezoelectric sensor invisible from the exterior.  
         [0017]     Furthermore, components, such as a sealing, can be arranged to fully or partially cover the sensor, at the body, without aggravating or influencing the components by the piezoelectric sensor. Additionally, the components need not be adjusted to the piezoelectric sensor in its structural shape.  
         [0018]     The sensor of the sensor system can, on the one hand, cover a large-surfaced body section so as to detect a possible crush risk in a large area by a single sensor. On the other hand, several small-surfaced sensors can also be arranged on the active vehicle part, the body section or the additional vehicle part, which are spatially offset and therefore receive a spatially differentiated signal. The position of the pressure and therefore the possible crushing can be determined by such a sensor arrangement; and dependant from the determined position, different measurements can be taken. If the sensors are set out as piezoelectric sensors, the small-surfaced sensors have the additional advantage that the parasitic capacitance of a sensor, which is conditional on the piezoelectric layer covered with electrodes, can be kept to a minimum.  
         [0019]     In another embodiment, the sensor system is part of a crush protection device for a window pane in a motor vehicle door thereby forming an active vehicle part. The sensor can be installed at a door frame of the motor vehicle door forming the body section or, in case of a door without frame, at a stationary body section of the vehicle body bordering the door opening. The sensor is thereby facing the closing window pane and is installed in an area which picks the active window pane up so that an object which is crushed between the window pane and the door frame, and in particular the body section of the vehicle body during the closing process of the window pane, is detected. It is also possible that the sensor is formed directly on the window pane, such as in the area of the upper window edge. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0020]     The present invention will be described in more detail below with reference to the appended figures, wherein:  
         [0021]      FIG. 1  depicts a side view of a motor vehicle door with a large-surfaced sensor applied at the door frame for a crush protection device;  
         [0022]      FIG. 2  depicts a side view of a motor vehicle door with several sensors applied at the door frame;  
         [0023]      FIG. 3  depicts a sectional view diagonal to the door frame with a piezoelectric sensor applied on the door frame; and  
         [0024]      FIG. 4  depicts a sectional view of a piezoelectric sensor. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]      FIG. 1  depicts a side view of a vehicle door  2  with a door frame  21  together forming a body section. The body section may be for the reception of the window pane  3  and further forming the active vehicle part where a sensor  1  may be applied. The sensor may cover the upper part of the door frame  21  on the side facing the window pane  3 . The sensor  1  is part of a sensor system of a crash protection device which serves as a security device for a moving of the window pane  3  and for the preventing of a closing whenever an object is detected between window pane  3  and door frame  21  and there is a risk that the object is crushed. The sensor  1  is applied on the closing window  3  facing the door frame  21  and covers the door frame  21 . The covering may be in areas where a crushing of an object is possible. If an object is between the window pane  3  and the door frame  21 , during the closing of a window pane  3 , and the object is crushed between them, then the object, at usage of a pressure-sensitive sensor, exercises pressure on the sensor, and the sensor  1  produces a signal and transmits the signal to a trigger circuit of the crush protection device. The trigger circuit evaluates the signal and prevents the closing process of the window pane  3 .  
         [0026]     The sensor  1  is applied on the door frame  21  and is adjusted to the shape of the door frame  21 . The sensor can be additionally covered by a layer of lacquer and therefore become invisible to the casual eye. The supply lines of the sensor  1  are applied so as to also be substantially invisible from the outside. Alternatively, the supply lines can be produced on the door frame  21  by precipitation of conducting material.  
         [0027]      FIG. 2  depicts a side view of a vehicle door  2  with several sensors  1   a - 1   j , spatially offset with respect to the door frame  21 . The several sensors cover one another at relatively small sectional areas of the door frame  21 . The sensors  1   a - 1   j  are connected by supply lines with the trigger circuit of the crush protection device. The crush protection device evaluated the signals of the individual sensors  1   a - 1   j  and started the suitable measurements depending upon the signals. For example, it is possible that, sooner or later, the trigger circuit prevents or decelerates the closing process in dependence of the position of the signal-giving sensors  1   a - 1   j . An arrangement according to  FIG. 3  is connected with a higher integration expense and a more complex trigger circuit. However, the arrangement can be produced in a relatively simple way, with minimized assembly expense, by successive precipitating steps of suitable material and the automated application of the sensors  1   a - 1   j  together with their supply lines.  
         [0028]      FIG. 3  depicts a cross section of a door frame  21  with a sensor  1  applied thereon. The sensor  1  comprises a thin layer as arranged on the door frame  21  and is partially covered by a seal  4  for the sealing of the window pane  3  when in a closed position. The sensor  1  is firmly connected with the door frame  21  and conformal to its contour. The sensor can therefore also be produced on curved body sections with complex shapes. If an object is crushed between the window pane  3  and the door frame  21 , then, at usage of a pressure-sensitive sensor, pressure is exercised on the sensor  1  at a location or in an area of the door frame  21 , a signal of the sensor  1  is produced and the closing process is interrupted. The crush protection device can also be set out in such a way that an object which only lightly touches the sensor  1 , or only approaches the sensor, interrupts the closing process of the window pane  3  so as to cause a timely reaction with respect to the risk of a possible crushing. Additional to the pressure-sensitive sensors, touch sensors or space-sensitive sensors, for example near field radar systems, whose antennas are applied conformal on the surface of the door frame as patch antennas and as shown in  FIG. 3 , can be used for this purpose.  
         [0029]     Preferably, the sensor  1  is set out as a pressure-sensitive piezoelectric sensor.  FIG. 4  depicts a sectional view of a piezoelectric sensor  1  which comprises a piezoelectric layer  11  and two electrodes  12 ,  13  and is formed as a pressure sensor in the form of a pressure sensitive layer. The piezoelectric sensor  1  is applied onto the body  2  of a vehicle and separated by an isolating layer  14  from the body  2 .  
         [0030]     Familiar piezo ceramic materials can be used for the production of the piezoelectric sensors  1 , which are applied layer-wise by precipitation on the body  2 . The piezoelectric layer  11  is thereby covered on both sides, at least partially, with electrodes  12  and  13 . An electrode  13 , facing the body, is first produced for application of the sensor on an isolating layer  14 . The piezoelectric layer  11  is precipitated on the electrode  13  and then the second electrode  12  is produced on the piezoelectric layer  11 . Because of the production in layers, the piezoelectric sensor  1  is adjusted in its shaping to the body  2 , is firmly connected to the body  2  and covers the body  2  uniformly.  
         [0031]     Because the body  2  of the vehicle normally comprises metal, it is conductive and the lower electrode  13  can be formed by the body  2 . The isolating layer  14  and the electrode  13  facing the body can then be omitted and the piezoelectric layer  11  formed directly on the body  2  and connected with it. In this case, the electrode formed by the body  2  is electrically on a mass potential.  
         [0032]     To design the piezoelectric sensor  1  as unobtrusively as possible from the outside, the sensor can be covered with a layer of lacquer and therefore adjusted, by way of color, to the body  2  without impairing the operability of the sensor  1 .  
         [0033]     During the exercising of pressure from the outside, i.e. from the side opposite to the body  2 , to the layer-wise piezoelectric sensor  1 , a tension is produced by the layer  11 , which causes a charge transfer and therefore a signal to the electrodes  12 ,  13  covering the piezoelectric layer  11  on both sides of which is further processed and evaluated by the trigger circuit of the crush protection device.  
         [0034]     The present invention includes other embodiments. For example, additional to the piezoelectric sensor systems, space sensitive sensors like near field radar systems are possible. The systems may have antennas which are precipitated directly onto the body or body part. Furthermore, crash protection systems are also possible for other vehicle parts. Such systems may, for example, be in the area of a vehicle door or the rear flap for the monitoring of the door closing travel, The present inventive concept can be carried over to a lot of possible applications, especially regarding motor vehicles, where sensors adjusted to the surface contour of the vehicle and applied layered-wise on the body or on parts of a vehicle, can be set up.