Patent Publication Number: US-6712409-B2

Title: External door handle for vehicles

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an external door handle, particularly for vehicles which when actuated acts through a connecting member on a lock. The handle includes a crash locking means for the connecting member, wherein the crash locking means is normally inactive. A crash sensor reacting to inertia forces renders the crash locking means active when a crash occurs. As a result, the crash locking means blocks the connecting means and an inertia force which acts on the handle as a result of the crash to actuate the handle is not transmitted to the lock. 
     2. Description of the Related Art 
     When the handle of a vehicle is actuated, a connecting member acts on a lock. In the event of a crash, inertia forces act on the handle and the members connected to the handle. These inertia forces may have the result that the handle carries out an undesirable actuating movement and opens the lock as a result. This causes the door to open and the passengers sitting in the vehicle could be ejected from the vehicle. Crash locking means are used to prevent this. 
     Such crash locking means act on the connecting member, but they are normally inactive. However, a crash sensor exists which reacts to inertia forces and makes the crash locking means active in the case of a crash. In that case, the connecting member is blocked and an actuation of the handle remains inactive. 
     It is known from DE 199 10 328 A1 to use a cylinder/piston unit between an external door handle and a connecting member which acts on a lock. A liquid is arranged in the cylinder and the piston has through openings which normally are held open by a blocking member, such as a sealing disk. When the door handle or the connecting member is initially quickly adjusted as the result of an accident, the piston is slightly moved in the liquid. The resulting flow of the liquid between the two chambers in the cylinder separated by the piston causes an at least slight pressure increase in one of the chambers, so that the blocking element closes the through opening. Any further movement of the piston in the cylinder is now no longer supposed to be possible. This known crash locking means is not operationally safe. The adjustment of the sensor in the interior of the cylinder to the correct reaction value is difficult. 
     Such crash locking means are usually constructed as a so-called “mass locking means”. For example, in an external door handle constructed as a pull handle and known from DE 20 23 859 B2, an additional mass acts on the shaft of the handle which serves as a connecting member. The additional mass is mounted on one arm of a two-arm lever and is biased by a tension spring which ensures that the arm of the lever normally engages behind a projection of the shaft. In the case of a normal actuation of the handle, this spring load is usually overcome, so that the lever releases the projection at the handle shaft. However, in the case of a crash, such a high inertia force acts on the additional mass that the other lever arm holds the projection and, thus, prevents an actuation of the handle resulting from an inertia force. Also, mass locking means interfere with the normal operation of the door handle. 
     It is also known in the art from DE 199 24 685 A1 to use between a latch and an actuating lever a switchable coupling which operates with an electrorheological liquid. The axis of the actuating lever is fixedly connected to a rotary cylinder which is located in a hollow cylinder. The hollow cylinder, in turn, is fixedly connected to the latch. The electrorheological liquid is located in the free space between the rotary cylinder and the hollow cylinder, where the electrodes for producing an electrical field are also located. In dependence on the electrical field, the liquid changes from a low viscous state through the plastic state to a solid state. When the liquid solidifies, the coupling is active and when the actuating lever is turned, the latch is also moved. The use of a crash sensor for controlling the state of aggregation of the liquid is not provided. 
     Finally, it is also known in the art from DE 197 54 167 A1 to use an electrorheological liquid for blocking a component which can be pivoted about an axis, for example, a door which is to be opened by a certain angle and then locked. A position sensor determines the respective angle position of the door and the position is made available to an electronic evaluation unit. The electronic evaluation unit compares the actual position of the door with the intended position and acts on an electronic control unit which controls the state of aggregation of the liquid through electrodes which are arranged on a rotary piston, on the one hand, and on a fixed cylinder, on the other hand. The rotary piston is fixedly connected to the door. Once the desired pivoting position of the door has been reached, the electrorheological liquid changes into its solid state which leads to locking of the door in the angle position. The use in connection with crash locking means is not provided. 
     SUMMARY OF THE INVENTION 
     Therefore, it is the primary object of the present invention to develop an external door handle of the type described above which avoids the disadvantages of the known crash locking means. 
     In accordance with the present invention, the connecting member of the door handle has a drive member which is movable with the connecting member. The drive member is arranged in a liquid medium and moves in this medium when the connecting member is actuated. The viscosity of the medium is changeable in dependence on an electrical field acting on the medium. The crash sensor controls the electrical field prevailing in the medium. 
     The crash locking means according to the invention operates in accordance with a principle which is completely different and novel as compared to the known crash locking means. In the event of a crash, the invention only changes the viscosity of the liquid medium. Such media are called “SKS-intelligent materials”. This medium changes its viscosity in dependence on an electrical voltage, i.e., in dependence on an electrical field prevailing in the medium. The medium is normally highly liquid and permits an easy movement of the drive member in the medium when the handle is actuated. The remaining flow resistance of the medium can even be usefully utilized for damping the actuation of the handle. This is of interest in case of door handles which are subject to a restoring force and which are supposed to move back into their initial positions as noiselessly as possible. In this connection, a principle can be utilized which is known from the very different field of “door closers”, in which the actuation of the handle is to be easy and smooth, but its return movement is to be dampened by suitable valves or labyrinths. 
     However, the gist of the invention resides in applying in the event of a crash an electrical field to the medium which is so high that a movement of the drive member in the medium is essentially blocked. It is sufficient for this purpose to provide a sensor which responds to inertia forces and actuates an electrical switch for an electrical field to be produced in the medium. The drive member and the medium can be located at any selected location in the chain of elements between the handle and the lock. Moreover, the crash sensor can also assume other functions, for example, transmitting an alarm of the accident through radio or the like to monitoring stations located outside of the vehicle. 
     The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     In the drawing: 
     FIG. 1 is a schematic top view, partially in section, of the rabbet of a door, shown in cross section; and 
     FIG. 2 is an axial sectional view, on a larger scale, showing a component of the device of FIG.  1 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An external door handle  10  serves for actuating a lock  20  which, in the illustrated case, has a rotary catch  21  as the closing means. As illustrated in FIG. 1, the rotary catch  21  is normally supposed to hold a door  15  in the closed position. In this position, the handle  10  is in a position of rest indicated by an auxiliary line  10 . 1  and the rotary catch  21  is in engagement with a locking bolt  22  which is mounted stationarily on the vehicle body. 
     The handle  10  can be actuated through an axis  11  mounted on a support member  12  in the direction of arrow  13 . The support member  12  is mounted on the inner side of an outer door lining  16  and an arm  14  acting on the handle  10  extends from the axis  11  through cutouts in the support member and the outer lining  16 . Restoring forces which are not identified in the drawing hold the grip  10  in the above-mentioned position of rest  10 . 1 . The movement  13  of the handle  10  is transmitted to a work arm  17  which is mechanically connected to the lock  20  through a special connection  30 . The connection includes a connecting member which in the illustrated embodiment is constructed as a longitudinally movable rod  31 , wherein one end of the rod  31  is connected to the work arm  17  of the handle  10  through a combined joint and push connection  18 . The other end of the rod is analogously coupled to an input member  23  of the lock  20  through a joint and push connection  28  provided at this location. 
     For opening the door  15 , the handle  10  is grasped and moved into the actuated position  10 . 2  shown in dash-dot lines in FIG.  1 . This movement  13  is transmitted to the work arm on the side of the handle, wherein the work arm then reaches the actuated position  17 ′ also shown in dash-dot lines in FIG.  1 . This results in a longitudinal movement  33  of the rod  31  indicated by an arrow in FIG.  1 . In this manner, the handle movement  13  is transmitted through the rod  31  to the input member of the lock which reaches the actuated position which is also shown in dash-dot lines. The rotary catch  21  is unlocked through the lock members following the input member  23 ′ and the locking bolt  22  is released. The door  15  can now be opened. 
     In the event of a crash, inertia forces act on the handle and the elements following the handle in the chain of elements up to the lock  20 . Consequently, in the case of an accident, the inertia force indicated in FIG. 1 by arrow  19  can act on the door  15 , wherein a component of the force is produced for carrying out a handle actuation  13 . Accordingly, in the case of an accident, there is the danger that the handle  10  is moved in an undesired manner into its actuated position  10 . 2  by the inertia forces acting directly or indirectly on the handle. If no other special precautions are taken, this leads to a movement  33  of the connecting member  31  and, thus, to an open position of the lock  20 . The door  15  opens and the passengers in the vehicle can be ejected and seriously insured as a result. This is prevented by a crash locking means which acts on the connecting member  31 , wherein the crash locking means according to the present invention is constructed in the manner illustrated in FIG.  2 . 
     Mounted on a rod  31  which acts as the connecting member is a drive member  32  which is movable with the rod  31 ; the drive member  32  is constructed as an axially fixed piston mounted on the rod  31 . The rod  31  extends through a cylinder  34  which serves as a container for a special medium  40 . The cylinder  34  is fixedly mounted in the door  15  at  29 , wherein, for this purpose, a suitable assembly strip  39  may be provided. For reasons of assembly, the cylinder  34  is composed of two axial portions  35 ,  36 , wherein the rod  31  extends through the two end faces of the cylinder, and wherein rod sealing means  37 ,  38  are provided at the end faces. 
     In the normal situation, the medium  40  in the interior of the cylinder is highly liquid. During a rod movement  33 , the piston  32  can be moved almost without any resistance within the cylinder interior. The remaining liquid flow of the medium  40  can advantageously be utilized for damping a return movement of the handle due to restoring springs from its actuated position  10 . 2  into its position of rest  10 . 1 . For this purpose, labyrinths and/or valves can be provided in the area of the piston  32  or the cylinder  34 . 
     However, in the case of an accident, the properties of the medium  40  are radically changed; the medium becomes extremely viscous. In this connection, a special property of the medium  40  is utilized which is the fact that the viscosity of the medium changes in dependence on an electrical field applied to the medium. By applying a sufficiently high electrical field, the medium  40  becomes so viscous that the piston  32  is stationary in the cylinder  34 . Thus, a movement  33  of the rod  31  is blocked. Consequently, the door handle  10  remains in its position of rest  10 . 2  even if high inertia forces  19  act on the handle during an accident. 
     FIG. 1 also shows schematically those electrical or electronic components which serve to produce the above-mentioned electrical field in the interior of the medium  40 . For this purpose, a crash sensor  25  is provided in the vehicle, wherein the crash sensor  25  responds when the inertia forces produced in the vehicle exceed a predetermined value. In that case, a signal is supplied through a line  26  to a control unit  24  which is in connection with a voltage source  27 . The voltage source  27  may be a vehicle battery. In the event of a crash, the control device  24  switches a switch which through electrical lines  41 ,  24  applies an electrical voltage to electrodes  43 ,  44  in the interior of the cylinder  34 . In accordance with the invention, the upper cylinder portion  35  is of a material which is capable of being insulated; for this reason, an electrically conductive material is located in the cylinder interior which serves as electrode  43  for connecting one line  41 . The lower cylinder portion  36  is already of an electrically conductive material so that its inner surface  44  may act as an electrode. Accordingly, the corresponding second electrical line  42  is connected to the container wall of this lower cylinder portion  36 . 
     The invention is not limited by the embodiments described above which are presented as examples only but can be modified in various ways within the scope of protection defined by the appended patent claims.