Patent Publication Number: US-2009218846-A1

Title: Trapping detection seal for opening leaves of vehicles

Description:
The invention relates to the field of trapping detection devices and methods for vehicle openings, and in particular the field of detection seals. 
     In this field, the U.S. Pat. No. 6,337,549 (BLEDIN) describes a capacitive sensor arranged at the top of an upright of a vehicle door to prevent the trapping of a finger when the door window is raised. The seal comprises an electrode inserted into a deformable part of the seal close to a metallic part linked to earth. An electrical device measures the capacitance between the electrode and earth. The drawback of such a capacitive seal is that it is influenced by the accidental proximity of materials other than those that the sensor is designed to detect. For example, water on the window or dead leaves can produce a variation in the capacitance between the electrode and earth, greatly disturbing the detection device. 
     The patent application EP-A-334 028 (BOSCH) describes a sensor for detecting the trapping of objects or parts of human bodies in the case of door windows, or roller blinds driven by an electric motor. The sensor comprises a conductive synthetic material, the electrical resistance of which can be modified by shape variation. A fault signal is triggered when the resistance leaves a predetermined range. Such a resistive device has the advantage over the capacitive sensor of measuring only the deformation of the sensor and sending a signal only from a deformation threshold. 
     The patent application FR-A-2 670 342 (PEUGEOT-CITROËN) describes a trapping or cutting-off detection device of a resistive seal. The resistive devices described in the above two documents have the drawback of being sensitive to deformation only in one direction. Now, in the case of a motor vehicle tailgate, it is commonplace for the fingers that need to be detected to bear on the side of the opening and not clearly perpendicularly to the seal, such that the force to which the finger must be subjected before the resistive seal detects its presence can be high. 
     The invention addresses the above problems, and in particular proposes a seal providing for a multidirectional trapping detection, so as to reduce the force suffered by a finger or any part of the human body trapped by the closing of a motorized opening. 
     According to one embodiment of the invention, the trapping detection seal for openings, in particular for motor vehicle openings, of elongate form, has an elastically deformable cross-section comprising a first hollowed-out zone arranged between a first conductive zone and a second conductive zone so as to enable the two conductive zones to come into contact with each other on deformation of the seal in a first direction. A second hollowed-out zone is arranged between the first conductive zone and a third conductive zone, the cross-section of the seal being deformable in at least one second direction, different from the first direction, to enable the first conductive zone to come into contact with the third conductive zone on deformation of the seal in the second direction. 
     It will be understood that such a seal, that can be deformed in at least two different directions and, in each of these directions, that can give rise to a contact between two conductive zones, will make it possible to detect forces originating, for example, from a finger, whether the latter exerts a force in one or other of the directions of deformation of the seal. This increases the directions of detection of the seal. 
     According to a variant, the two hollowed-out zones of the cross-section communicate. 
     According to another variant, the cross-section comprises an insulating zone mechanically linking the conductive zones. The insulating zone can be made of elastomer or rubber. 
     Advantageously, the insulating zone has four portions of lesser thickness providing articulation for the deformation of the seal. 
     Advantageously, the cross-section comprises a cross-shaped hollowed-out zone separating four conductive zones. 
     According to another variant, the cross-section comprises four lobes of compressible material corresponding to the four portions of lesser thickness. 
     According to a variant, the seal presents over its length at least one cross-section provided with a bead having a catching shape designed to cooperate with a chassis frame of the vehicle or with an opening of the vehicle. 
     According to another variant, the cross-section of the longitudinal seal can be deformed under the effect of two opposing radial forces, the direction of said forces lying within a cone of deformation which comprises at least the first and second directions. 
     Advantageously, the cone of deformation is symmetrically distributed relative to the bead and presents an opening angle greater than 80 degrees. 
     According to another variant, at least one of the conductive zones comprises a cross-section of metal wire, surrounded by a cross-section of sheathing made of polymer material charged with metallic micro-particles or charged with carbon. 
     According to another aspect of the invention, it relates to a trapping detection method for openings, in particular motor vehicle openings. The method comprises a step in which a contact between two conductive zones of a seal is detected and the cross-section of the seal is deformed in a direction taken from at least two possible directions of deformation. 
     Advantageously, the detection of the contact is made by measuring the resistance between a first conductive zone on the one hand and at least two other conductive zones on the other hand. 
     According to another aspect of the invention, a detection seal is used to detect the presence of a body located in the closure path of a motorized vehicle opening. 
     In one use of the seal, the second and third conductive zones are linked in parallel with termination resistors and with an electrical resistance measuring device so that the contact between any two conductive zones of the seal is reflected in a lowering of the measured electrical resistance by at least a threshold value, a computer then controlling a freeing sequence on the motor operating the opening. 
    
    
     
       Other characteristics and advantages of the invention will become apparent from reading the detailed description of several embodiments of the device, taken as nonlimiting examples and illustrated by the appended drawings, in which: 
         FIG. 1  is a cross-section of an inventive detection seal in the free state; and 
         FIG. 2  is a cross-section of a detection seal in the deformed state. 
     
    
    
     As illustrated in  FIG. 1 , the cross-section  1  of the trapping detection seal comprises an insulating zone  2 , four conductive zones  3  and a hollowed-out zone  4  located at the center of the cross-section  1 . 
     The insulating zone  2  is delimited externally by a substantially circular surface  5  and by a bead-shaped catching zone  6 , not shown in the figure, and designed to catch the seal on a chassis frame of the vehicle or on an opening of the vehicle. The insulating zone  2  has an internal delimitation consisting of eight lobes  7  that are contiguous and substantially circular and distributed over the four sides of a square  8 , the sides of the square  8  having a length roughly twice the diameter of the lobes  7 . The insulating zone  2  is made of unfilled polymer, for example of rubber. 
     The four conductive zones  3  are of substantially circular shape and housed in the lobes  7  located in the middle of the sides of the square  8 . 
     The hollowed-out zone  4  is cross-shaped and comprises the four lobes  7  located at the summits of the square  8 . The hollowed-out zone  4  has a non-zero thickness separating two conductive zones  3 , either side of each of the arms of the cross shape of the hollowed-out zone  4 . 
     A first conductive zone  3   a  is located on the side of the square  8  opposite to the catching zone  6 . A second conductive zone  3   b  is located on the right side of  FIG. 1  and a third insulating zone  3   c  is located on the left side. A fourth conductive zone  3   d  comprises the catching zone  6 . Each of the conductive zones  3   a ,  3   b,    3   c,    3   d  comprises in its center an electrical wire  9   a,    9   b,    9   c,    9   d  surrounded with a sheathing  16  made of polymer filled with metallic micro-particles or even filled with carbon. The conductive zones  3  adhere to the insulating zone  2  and form a deformable single-piece assembly. The thickness of the insulating zone  2  located between the lobes  7  at the summit of the square  8  and the circular surface  5 , constitutes four portions of lesser thickness  10 . 
     A force on the external surface of the seal provokes an overall deformation of the seal illustrated in  FIG. 2 . In particular, this force can have a first direction  11  aligned with a diagonal of the square  8 . A force in a second direction  12  corresponding to the other diagonal of the square  8  would provoke a deformation symmetrical to that illustrated in  FIG. 2 . 
     There now follows a description of the effect of the deformation according to the favored direction  11 . The four portions of lesser thickness  10  behave like articulation zones, enabling the square  8  to be deformed to assume a lozenge shape  8   a.  During this deformation the distance separating the perimeter of the first conductive zone  3   a  from the perimeter of the second conductive zone  3   b  diminishes until the conductive zones  3   a  and  3   b  come into contact. In parallel, the conductive zones  3   c  and  3   d  also come into contact. Conversely, the distance separating the first conductive zone  3   a  from the third conductive zone  3   c  increases. 
     Before the perimeters of the first conductive zone  3   a  and of the second conductive zone  3   b  come into contact, the electrical resistance between the electrical wires of the conductive zones  3   a  and  3   b  is due only to the resistance of the insulating zone  2  and, for example, is greater than 10 Kohms. Immediately the perimeters of the conductive zones  3   a  and  3   b  come into contact, the resistance between the two electrical wires  9   a  and  9   b  drops sharply to a first threshold value, for example less than 5 Kohms. When the seal continues to be deformed and the deformation of the conductive sheathings  16  surrounding the electrical wires  9   a  and  9   b  is provoked, the convergence of the conductive particles of the filled polymer helps greatly to reduce the resistance between the two electrical wires  9   a  and  9   b,  to reach a value of the order of 300 ohms. 
     There now follows a description of the use of the detection seal to detect the presence of a body located on the closing path of a motorized opening of a motor vehicle. The opening can, in particular, be a tailgate pivoting about a horizontal hinge located in the top part of the tailgate. The opening can also be a swinging or sliding side door. Many vehicles are equipped with a motorized closure mechanism, handling the last centimeters of closure. Until the door or tailgate has reached these final centimeters, the presence of a finger in the zone separating the opening from the chassis frame of the vehicle can be tolerated by a deformable seal to enable the trapped part of the body to be removed rapidly. The trapping detection seal makes it possible to stop the final motorized convergence of the opening. The trapping detection seal covers all the area where the opening is opposite the chassis frame of the vehicle and can be fixed, either to the opening, or to the chassis frame of the vehicle. The four electrical wires  9   a,    9   b,    9   c,    9   d  of the four conductive zones  3   a,    3   b,    3   c,    3   d  extend all along the detection seal. A termination resistor of the order of several Kohms is located at one end of the seal and connected on one side to the ends of the electrical wires  9   a  and  9   d  and on the other side to the electrical wires  9   b  and  9   c.  On the other side of the seal, a measuring set measures the resistance between an end that is common to the electrical wires  9   a  and  9   d  and an end that is common to the electrical wires  9   b  and  9   c . When an obstacle flattens, at at least one point, a cross-section  1  of the detection seal, the measured resistance falls below the value of the termination resistor, because the latter has been short-circuited by the contact between the electrical wires  9   a  and  9   b  coated with filled polymer. The measuring set then sends a command to a motor to suspend the closure of the opening. The measuring set can also control a freeing sequence consisting, for example, in re-opening the opening to enable the obstacle, such as the finger of a child, to be removed from the closure zone. 
     In a variant, the termination resistor is located on the same side of the seal as the resistance measuring device, between the electrical wires  9   c  and  9   d,  the resistance measurement being made between the ends of the wires  9   a  and  9   b.  At the opposite end of the seal, the electrical wires  9   a  and  9   d  are linked together. Similarly, the ends of the wires  9   b  and  9   c  of the same end of the seal are linked together. Thus, any contact between the first conductive zone  3   a  with one or other of the second and third conductive zones  3   b  and  3   c  is detected. 
     There now follows a description of the deformation of the seal when subjected to a compression force, in a direction lying between the first direction  11  and the second direction  12 . When a force compresses the seal in a direction  13  that is roughly perpendicular to the square  8  opposite to the catching zone  6 , the lobes  7  are deformed and the square  8  is transformed into an elongate polygon (bean-shaped) with the same perimeter as the square  8  until the first conductive zone  3   a  comes into contact with the fourth conductive zone  3   d . With a force in a direction  14 , lying between the first direction  11  and the third direction  13 , the square  8  is transformed into a parallelogram, the large side of which is parallel to the catching zone  6  and the small inclined sides of which comprise the second and third conductive zones  3   b  and  3   c.  The deformation of the seal takes place until the conductive zone  3   a  comes into contact, either first with the conductive zone  3   b,  or simultaneously with the conductive zones  3   b  and  3   d,  or only with the conductive zone  3   d.  There is detection continuity whatever the direction of the force lying between the first direction  11  and the third direction  13 . Because of symmetry, the same applies for the forces lying between the second direction  12  and the third direction  13 . The seal presents a cone of deformation comprising at least the first and second directions  11  and  12  and presenting an opening angle of 90°. 
     The spring formed by the deformable seal presents a stiffness that is much higher in the transverse direction  13  than in the two favored directions of deformation that are the first direction  11  and the second direction  12 . The stiffness in an intermediate direction  14  presents a value between a high stiffness in the transverse direction  13  and a low stiffness in the direction  11 . The angular distribution of the stiffness of the seal presents a local minimum value for each of the two favored directions of deformation  11  and  13 . 
     In the case where the bead for fixing onto the chassis frame, at the point of the catching zone  6 , is able to withstand a torque, a horizontal force pushing the third conductive zone  3   c  to the right of the figures provoke a deformation that is similar to that illustrated in  FIG. 2 . The opening angle of the cone of deformation is 180°. 
     According to another embodiment variant of the seal, the latter has a flange shape with no catching bead, positioned at intervals by gluing points on the chassis frame of the vehicle. Such a catching method in the zone  6  cannot resist a torque. The seal, however, presents a cone of deformation of 90°, regardless of the angular position occupied by the catching zone relative to the four conductive zones. In this variant, the electrical configuration needed to detect a trapping situation favors the behavioral symmetry of the four conductive zones  3  and places three resistors in series between each of the four wires, the resistance measuring device being connected between an end wire and the other end wire through a fourth resistance. The contact between any two conductive zones  3  taken from the four, causes the resistance perceived by the measuring set to be lowered by at least a resistance value, which is sufficient to detect the trapping and provoke the stoppage of the motor driving the opening of the vehicle. 
     When the seal is provided with a fixing bead, the first conductive zone has a priority role and the electrical connection can be a star configuration where one end of the seal is fitted with three resistors linking the wire  9   a  to each of the second, third and fourth wires  9   b,    9   c  and  9   d.  At the opposite end, the measuring device checks the resistance between the wire  9   a  and the three parallel-connected ends of the wires  9   b,    9   c  and  9   d.    
     According to another embodiment, the four lobes of the hollowed-out zone  4  located at the summit of the square  8 , corresponding to the four portions of lesser thickness  10 , can be filled with compressible and insulating material other than air or vacuum, such as foam. It is, however, important for the space separating two adjacent conductive zones to remain free, so as to enable their contact when the seal is deformed. 
     According to yet another variant, it is possible for the second  3   b,  third  3   c  and fourth  3   d  conductive zones to form only a single conductive assembly, substantially fixed relative to the catching bead, surrounding the first conductive zone  3   a  over an arc of circle, while being separated from it by a hollowed-out zone  4 . The conductive assembly presents a concave surface opposite the first conductive zone  3   a.  The first conductive zone  3   a  remains joined to the insulating part  2  that can be deformed in at least the first direction  11  and in the second direction  12 , and more generally, in any one of the directions lying within a cone of deformation. Whatever the direction of the compression force, the first conductive zone  3   a  comes into contact with the conductive assembly at any one of the contact points of the concave surface. 
     According to yet another variant, the hollowed-out zone  4  can be partitioned into several separate hollowed-out zones, the partition being deformable.