Abstract:
A force adjustment system that inhibits door handle actuation is provided. The force adjustment system includes a sensor configured to provide a signal in response to an input. An energy source is configured to provide an output in response to the signal. A force adjustment component is configured to be linked to a door handle assembly. The force adjustment component comprises a material having a property that is changed in response to the output provided by the energy source to change a force applied to a handle of the door handle assembly.

Description:
TECHNICAL FIELD 
     The present invention generally relates to door handles and, more specifically, to adaptive door handles that provide increased resistance to opening. 
     BACKGROUND 
     Door handle assemblies for vehicles may use a return spring to effectuate actuation of both a door handle and an associated latch mechanism. The door handle may be pivotally connected to the door such that an operator can actuate the door handle to open the door. 
     A door handle spring may be connected to the door handle. The door handle spring may bias the door handle toward its closed position such that when the door handle is released by the operator, the door handle moves from its open to its closed position. The spring bias also inhibits unintended actuation of the door handle. 
     Because door handles are generally actuated manually, the stiffness of the door handle spring may not be so high as to make manual actuation of the door handle difficult. However, the spring stiffness may be high enough to inhibit unintended actuation of the door handle in certain situations, such as upon a side impact. Thus, it would be desirable to provide a door handle assembly having a resistance to unintended actuations, but yet can be easily opened by the operator. 
     SUMMARY 
     In one embodiment, a force adjustment system that inhibits door handle actuation is provided. The force adjustment system includes a sensor configured to provide a signal in response to an input. An energy source is configured to provide an output in response to the signal. A force adjustment component is configured to be linked to a door handle assembly. The force adjustment component comprises a material having a property that is changed in response to the output provided by the energy source to change a force applied to the door handle assembly. 
     In another embodiment, a door handle assembly includes a door handle having an open position and a closed position. A force adjustment system includes a sensor configured to provide a signal in response to an input. An energy source is configured to provide an output in response to the signal. A force adjustment component includes a material having a property that is changed in response to the output provided by the energy source to change a force applied to the door handle. 
     In another embodiment, a door includes a door handle assembly having an open position and a closed position. A force adjustment system is connected to the door handle assembly. The force adjustment system includes a sensor configured to provide a signal in response to an input and a force adjustment component comprising a material having a property that is changed to impede movement of the door handle assembly from a closed position to an open position. 
     These and additional features provided by the embodiments of the present invention will be more fully understood in view of the following detailed description, in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments set forth in the drawings are illustrative and exemplary in nature and not intended to limit the inventions defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which: 
         FIG. 1  is a perspective side view of an embodiment of a door for a vehicle; 
         FIG. 2  is a schematic illustrating a top view of an embodiment of a door handle assembly for the door of  FIG. 1  in a closed configuration; 
         FIG. 3  is a schematic illustrating a top view of the door handle assembly of  FIG. 2  in an open configuration; 
         FIG. 4  is a schematic illustrating an embodiment of a vehicle with door handle assemblies; 
         FIG. 5  is a schematic illustrating an embodiment of a spring force adjustment system; 
         FIGS. 6 and 7  are schematics illustrating operation of an embodiment of a spring force adjustment system; 
         FIG. 8  is a schematic illustrating operation of an embodiment of a spring force adjustment system; 
         FIG. 9  is a schematic of a spring force adjustment system; 
         FIG. 10  is a schematic of a spring force adjustment system; 
         FIG. 11  is a schematic illustrating operation of an embodiment of a spring force adjustment mechanism; 
         FIG. 12  is a schematic illustrating a top view of an embodiment of a door handle assembly; 
         FIG. 13  illustrates an embodiment of a method of inhibiting door opening; 
         FIG. 14  is a schematic illustrating an embodiment of a door handle assembly in the closed configuration; 
         FIG. 15  is a schematic illustrating the door handle assembly of  FIG. 14  in the open configuration; and 
         FIG. 16  is a schematic illustrating inertia forces due to acceleration on the door handle assembly of  FIG. 14 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a door  10  of a vehicle is illustrated and includes a door handle assembly  12  including a door handle  14  that is located at an exterior panel  16  of the door. In this embodiment, the door handle  14  is in the shape of a bend or U-shape and can be opened by grasping an intermediate portion  18  of the door handle and pulling in an outward direction away from the door  10  in the direction of arrow  20 . Once the door handle is placed in the open position, the door  10  can be opened by pivoting the door about axis A relative to a vehicle frame. In some embodiments, the door handle  14  returns to its closed position once released. While an outward pulling door handle configuration is shown by  FIG. 1 , other configurations are possible, such as a vertical lifting-type door handle. 
       FIGS. 2 and 3  illustrate the door handle assembly  12  schematically in a closed position ( FIG. 2 ) and an open position ( FIG. 3 ). The door handle assembly  12  includes the door handle  14 , which is linked to a latch component  16  (e.g., a bell crank). The physical link between the door handle  14  and the latch component  16  is omitted for clarity, however, the link between the door handle and the latch component can be accomplished by any suitable connection. The latch component  16  can rotate about a pivot P in response to actuation of the door handle  14  in the direction of arrow  20 . An actuation member (represented by arrow  22 ) connects the latch component  16  to a door latch mechanism  27  such that, with the door handle  14  in the closed position ( FIG. 2 ), the door latch mechanism is locked to prevent the door  10  from opening and, with the door handle in the open position ( FIG. 3 ), the door latch mechanism is unlocked to allow the door to open. 
     As can be seen in  FIGS. 2 and 3 , the door handle assembly  12  includes a door handle spring  24 . The door handle spring  24  may be a torsion-type spring that is connected to the latch component  16  so as to bias the latch component and the door handle  14  toward the closed position due to the linkage between the latch component and the door handle. The door handle spring  24  may obey Hooke&#39;s law, which states that the force with which the spring pushes back is linearly proportional to the distance from its equilibrium length:
 
 F=−kx,  
 
     where 
     x is the displacement vector—the distance and direction in which the spring is deformed, 
     F is the resulting force vector—the magnitude and direction of the restoring force the spring exerts, 
     k is the spring constant or force constant of the spring. 
     Of course, a torsion spring may follow an angular version of Hooke&#39;s law where the amount of torque the spring exerts is proportional to the amount the spring is twisted. 
     In some embodiments, the door handle spring  24  may be pre-loaded when connected to the latch component  16 . This can provide a greater biasing force that must be overcome when initially actuating the door  10  than would be provided if the door handle spring  24  were it its equilibrium position. In some embodiments, a counter weight  26  is provided at an end of the latch component  16  opposite the end of the latch component connected to the door handle  14 . The counter weight  26  may be used to stabilize the door handle  14  and allow for use of a door handle spring  24  having a lower spring constant so that the door handle assembly  12  can be more easily actuated by an operator to open the door. 
       FIG. 4  schematically illustrates a vehicle  30  with the door handle assembly  12   a  and the door handle assembly  12   b . The door handle assembly  12   a  is located at a driver&#39;s side door  32  of the vehicle for use in opening and closing the driver&#39;s side door. The door handle assembly  12   b  is located at a passenger&#39;s side door  34  for use in opening and closing the passenger&#39;s side door. While the door handle assemblies  12   a  and  12   b  are shown in use with a two-door car, the door handle assemblies may be used with other vehicle types such as those having 4-doors or more, trucks, vans, recreational vehicles, trailers, etc. 
     For purposes of explanation, a sudden sideways acceleration, such as may be provided as a result of a side impact to the vehicle  30 , as represented by arrow  38 , tends to generate potential door opening forces due to inertia. For example, a sudden acceleration in the direction of arrow  38  results in an inertial force  40   a  applied to the door handle  14   a , an inertial force  40   b  applied to door handle  14   b , an inertial force  42   a  applied to counter weight  26   a  and inertial force  42   b  applied to counter weight  26   b.    
     As can be seen by  FIG. 4 , a sudden acceleration in the direction of arrow  38  results in the inertial force  40   a  that tends toward opening the door handle  14   a . However, the inertial force  42   a  applied to the counter weight  26   a  along with the spring force of the door handle spring  24  tend to prevent opening of the door handle  14   a  by offsetting the inertial force  40   a . Thus, in this instance, a heavier counter weight  26   a  may be desirable to inhibit outward movement of the door handle  14   a . At the passenger&#39;s side (the side opposite the side where the acceleration is applied), the inertial force  42   b  applied to the counter weight  26   b  tends toward opening the door handle  14   b . However, the inertial force  40   b  applied to the door handle  14   b  along with the spring force of the door handle spring  24  tend to prevent opening of the door handle  14   b . Thus, in this instance, a lighter counter weight  26   b  may be desirable to inhibit outward movement of the door handle  14   b . However, a sudden acceleration in the direction of arrow  36  may result in opposite inertial forces. Thus, it may also be desirable to provide similar or identical door handle assemblies  12   a  and  12   b . For both the driver&#39;s side and passenger&#39;s side door assemblies  12   a  and  12   b , the door handle spring  24  operates against opening of the door assemblies during acceleration  36  or acceleration  38 . 
     Referring to  FIG. 5 , a spring force adjustment system  50  is provided that alters the force that the door handle spring  24  applies to the door handle  14  during sudden accelerations, for example, accelerations above a pre-selected threshold acceleration. The spring force adjustment system  50  includes a spring force component  52  that is linked to the door handle spring  24  or to the latch component  16  by a linkage  54 . The spring force component  52  may be in the shape of a coil and be formed of a shape memory material. A shape memory material is a material (e.g., an alloy) that remembers its shape, and can be returned to that shape after being deformed, for example, by applying (or removing) a suitable stimuli such as heat to the material. Smart materials may exist in two phases: a martensite phase and an austenite phase. The martensite phase is typically relatively soft and easily deformable. In contrast, the austenite phase is typically stiffer than the martensite phase. When heated, the smart material may transition from the martensite to the austenite phase. Suitable materials may include copper-based and NiTi (nickel and titanium)-based shape memory alloys. 
     A side sensor  58 , such as an accelerometer, a pressure sensor or a combination of sensors, may be used to detect side-to-side accelerations of the vehicle. The side sensor  58  may provide a signal  63  indicating an input, such as a sudden acceleration (e.g., above the threshold acceleration) or side impact to a power source  60 , such as a power source for a power lock in the door, or any other suitable power source. The power source  60  may be used to provide an output energy  65  (e.g., resistive heat) or any other suitable activation signal to the spring force component  52  in response to a signal from the side sensor  58 . Any suitable resistive heating element may be used. In some embodiments, it may take about 10 milliseconds or less for the spring force adjustment system  50  to respond to a sudden side acceleration. The energy may be removed once the side sensor  58  no longer senses the acceleration above the threshold acceleration. In some embodiments, the side sensor  58  may provide the signal to a controller  61 . The controller  61  may control operation of the power source  60  and monitor the signal  63  from the side sensor  58 . 
     Producing the activation signal may include sensing an increased probability of an impact event in the near future, the occurrence of an impact event, manual activation by an occupant or person servicing the vehicle, electronic activation of a built-in logic control system such as activation of a vehicle stability enhancement system (VSES), turning on or off the ignition and the like. Sensing an impact may be accomplished with an impact sensor, pre-impact sensor such as a radar system, vision systems, activation of anti-lock braking systems (ABS) and the like. 
     The spring force component  52  may have two-way shape memory for remembering two different shapes, for example, one at low temperatures and one at high temperatures. A material that shows a shape memory effect during both heating and cooling may be called a two-way shape memory material. The shape memory material may be trained to learn to behave in a certain way. Under normal circumstances, a shape memory material may remember its high-temperature shape, but upon heating to recover the high-temperature shape, immediately forget the low-temperature shape. However, the shape memory material may be trained to remember to leave some reminders of the deformed low-temperature condition in the high-temperature phases. Any suitable method of training the shape memory material may be utilized. 
     Suitable shape memory materials may exhibit a one-way shape memory effect or a two-way shape memory effect depending, for example, on the material composition and processing history. In contrast to the two-way shape memory, the one way shape memory materials do not automatically reform and may require an external force to reform the shape orientation that way previously exhibited. 
     In some embodiments, the spring force component  52 , in the form of the coil, contracts (e.g., between about two percent and about 10 percent or more) when energy is applied and returns to its original shape when the energy is removed. Referring to  FIGS. 6 and 7 , the linkage  54  may be connected to the spring force component  52  such that it is displaced (e.g., rotates, translates, etc.) in response to contraction of the spring force component. The linkage  54  may be relatively rigid and connected to the door handle spring  24  at an end opposite the spring force component  52 . Displacement of the linkage  54  may cause the door handle spring  24  to twist, displacing the door handle spring a greater distance from its equilibrium position (e.g., from θ 1  to θ 2 ), thereby increasing the biasing force (or torque τ 1  to τ 2 ) applied to the door handle  14 . 
     In another embodiment, the spring force component  52  may be used to increase the stiffness of the door handle spring  24 , for example, by engaging the door handle spring with the linkage  54  in response to contraction of the spring force component. For example, referring to  FIG. 8 , the linkage  54  may engage a leg  55  of the door handle spring  24  to resist its movement and resist movement of the door handle assembly  12  toward the open position. In normal operation, the spring force component  52  may allow relatively unimpeded movement of the leg  55 . When the spring force component  52  is actuated, the spring force component may provide resistance to movement of the leg  55 , which may increase spring stiffness. Such an increase in spring stiffness can increase the bias force on the door handle  14 . 
     Referring to  FIG. 9 , the spring force component  52  may, itself, form the door handle spring  24 . In the martensite phase, the spring force component  52  in the form of a torsion spring, may have a spring constant that is relatively low, yet is suitable for biasing the door handle  14  toward the closed position under normal operating conditions. When the spring force component  52  is actuated, transitioning to the austenite phase, the spring force component may contract into a smaller shaped spring and the elastic modulus may be higher (e.g., about 70 GPa for NiTi) compared to the elastic modulus of the spring force component in the martensite phase (e.g., about 30 GPa for NiTi). Thus, the spring force component  52  may have a higher spring constant in the austenite phase than in the martensite phase. Such an increase in spring stiffness can increase the bias force on the door handle  14  and maintain the door handle in the closed position. 
     In some embodiments, it may be desirable to increase the biasing force applied to the door handle  14  by about 10 percent or more, such as about 20 percent or more, such as about 25 percent or more, or such as about 40 percent or more. In certain embodiments, it may be desirable for the biasing force to be at least about 70 Newtons (e.g., between about 70 and about 90 Newtons) with the door handle assembly in its higher torque configuration and the biasing force to be less than about 70 Newtons (e.g., between 30 and about 70 Newtons) with the door handle assembly in its lower torque configuration under normal operating conditions with the door handle  14  in the closed position. 
     Referring to  FIG. 10 , another embodiment of a spring force adjustment system  62  includes a damper  64  that may be formed of a smart material. A linkage  66  links the damper  64  and the door handle spring  24 . The linkage  66  is linked to the door handle spring  24  (e.g., one of the legs of the door handle spring) such that is movable therewith. The side sensor  58  detects side-to-side accelerations of the vehicle. The side sensor  58  may provide a signal  63  indicating a sudden acceleration to the power source  60 . The power source  60  is used to provide an input stimulus (e.g., a magnetic field using an electromagnet) to damper  64  in response to a signal from the side sensor  58 . Referring to  FIG. 10 , under normal operating conditions, the damper  64  is in a relatively low dampening configuration to allow movement of the linkage  66 . Once a sudden side acceleration is detected by the side sensor  58 , the damper  64  is placed in a relatively high dampening configuration to impede movement of the linkage, which, in turn, impedes actuation of the door handle  14 . 
     In another embodiment, the damper  64  may be used to resist movement of the latch mechanism  16 . For example, referring to  FIG. 12 , the damper  64  may be located at pivot P. Under normal operating conditions, the damper  64  is in a relatively low dampening configuration to allow movement of the latch mechanism  16  about P. Once a sudden side acceleration is detected by the side sensor  58 , the damper  64  is placed in a relatively high dampening configuration to impede movement of the latch mechanism  64  about P by providing increased friction, which, in turn, impedes actuation of the door handle  14 . 
     Any suitable material can be used in forming the damper  64 . One exemplary material is a magnetorheological fluid (MR fluid). An MR fluid is a suspension of micrometer-sized magnetic particles in a carrier fluid, usually an oil. When subjected to a magnetic field, the MR fluid greatly increases its apparent viscosity, to the point of becoming a viscoelastic solid. The yield stress of the fluid when in its active state can be controlled very accurately by varying the magnetic field intensity. Thus, the MR fluid&#39;s ability to transmit force can be controlled with an electromagnet. Other possibilities for forming the damper  64  include shape memory polymers and electro active polymers. 
     Referring to  FIG. 13 , a method  70  of inhibiting door opening includes assembling a door handle assembly  12  at step  72 . The door handle assembly  12  includes the door handle  14 , the latch component  16  and the door handle spring  24  that is used to bias the door handle toward the closed position. The spring force adjustment system  50  is connected or linked to the door handle assembly at step  74 . The spring force adjustment system  50  includes a spring force component  52  that is linked to the door handle spring  24  or to the latch component  16  by a linkage  54 . The spring force component  52  may be formed of a smart material, such as a shape memory material or a smart material damper, having a first configuration and a second configuration. The spring force component  52  is linked to the door handle assembly  12  such that a greater bias force is applied to the door handle with the spring force component in the second configuration and a lesser bias force is applied to the door handle with the spring force component in the first configuration. 
     At step  76 , the spring force adjustment system  50  may sense a sudden sideways acceleration using the side sensor  58 . A signal is sent from the side sensor  58  to the energy source  60  at step  78 . The energy source  60  provides a stimulus (e.g., heat, magnetic field, etc.) to the smart material at step  80 . The spring force component  52  transforms from the first configuration associated with a low spring bias force to the second configuration associated with a high spring bias force at step  82 . 
     While particular embodiments and aspects of the present invention have been illustrated and described herein, various other changes and modifications can be made without departing from the spirit and scope of the invention. For example,  FIGS. 14 and 15  illustrate another door handle assembly  84  that is actuated by lifting vertically on a door handle  86 . The door handle assembly  82  includes a counter weight  88  and a door handle spring  90  for biasing the door handle assembly to its closed configuration.  FIG. 14  illustrates the door handle assembly in the closed configuration and  FIG. 15  illustrates the door handle assembly in the open configuration.  FIG. 16  illustrate forces created due to a sudden side acceleration in the direction of arrow  92 . The spring force adjustment systems  50  and  62  may be used to increase the bias force applied to the door handle during such sudden accelerations to reduce the possibility of unintended door opening, yet provide for easy actuation and opening of the door handle assembly under normal operating conditions. Moreover, although various inventive aspects have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that are within the scope of this invention.