Abstract:
A hinge is provided for pivotably mounting a first attachment member to a second attachment member. A first member is attached to the first attachment member. A second member pivotably engages the first member and is disposed within the first member. The second member is configured for attachment to the second attachment member. An annular cavity is disposed between the first member and the second member. The annular cavity maintains a spaced relationship between the first member and the second member. A magnetorheological fluid is disposed within the annular cavity. A magnetic field generating member is configured to produce a change in a shear strength of the magnetorheological fluid within the annular cavity. The magnetorheological fluid applies a variable resistance torque between the first member and the second member for controlling a pivoting motion between the first member and the second member.

Description:
BACKGROUND OF INVENTION 
       [0001]    An embodiment relates generally to hinge devices. 
         [0002]    Various moving components utilize a hinge to pivot from one position to another position. A hinge is typically a type of bearing that is secured to two moving objects and allows a respective angle of rotation between them. The two objects that are connected by the hinge rotate relative to each other about a respective fixed axis of rotation. 
         [0003]    The ability the hinge to freely rotate depends on, among other factors, the resistance built into the bearing surface of the hinge when it is manufactured. Typically, a resistance member is added to the hinge assembly that applies a resistance force to slow down or soften the opening of the two members. For example a vehicle door may have spring-like member that provides a resistance for slowing pivoting of the two components. This is typically preferred when it is undesirable to have a member pivot fast to its open or closed position where the speed of the moving member when it reaches the end of travel may generate a counter force in moving the opening part back towards its original position. The resistance member is typically a mechanical part that requires additional cost and packaging space. 
       SUMMARY OF INVENTION 
       [0004]    An advantage of an embodiment is controlling the movement of a hinge assembly by controlling magnetorheological (MR) fluid within an annular cavity formed between a fixed member and a pivoting member of a hinge assembly via a magnetic field exerted on the MR fluid. The magnetic field may be generated by permanent magnets, electromagnets, or a combination of both permanent magnets and electromagnets formed within the hinge assembly. The magnetic field may be variably controlled to control the speed that the hinge is able to rotate and may control the distance that the hinge assembly is pivotably displaced. This is accomplished within a relatively small package space, and allows for variable control of the hinge. 
         [0005]    An embodiment contemplates a hinge for pivotably mounting a first attachment member to a second attachment member. A first member is attached to the first attachment member. A second member pivotably engages the first member and is disposed within the first member. The second member is configured for attachment to the second attachment member. An annular cavity is disposed between the first member and the second member. The annular cavity maintains a spaced relationship between the first member and the second member. A magnetorheological fluid is disposed within the annular cavity. A magnetic field generating member is configured to produce a change in a shear strength of the magnetorheological fluid within the annular cavity. The magnetorheological fluid applies a variable resistance torque between the first member and the second member for controlling a pivoting motion between the first member and the second member. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0006]      FIG. 1  is a perspective view of a working hinge. 
           [0007]      FIG. 2  is a schematic, partial cut away section of the hinge assembly according to a first preferred embodiment. 
           [0008]      FIG. 3  illustrates the magnetic field generated by the magnetic field generating member according to the hinge assembly shown in  FIG. 2 . 
           [0009]      FIG. 4  is a schematic, partial cut away section of the hinge assembly according to a second preferred embodiment. 
           [0010]      FIG. 5  illustrates the magnetic field generated by the magnetic field generating members according to the hinge assembly shown in  FIG. 4 . 
           [0011]      FIG. 6  is a schematic, partial cut away section of the hinge assembly according to a third preferred embodiment. 
           [0012]      FIGS. 7   a - 7   c  illustrate various magnetic field generated by the magnetic field generating members according to the hinge assembly shown in  FIG. 6 . 
           [0013]      FIG. 8  is a schematic, partial cut away section of the hinge assembly according to a fourth preferred embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    There is shown in  FIG. 1  a hinge assembly  10  secured to a first attachment member  12  and a second attachment member  14 . It should be understood that the first attachment member  12  or the second attachment member  14  may be integrally formed as part of the hinge assembly  10  or may be secured by other methods including, but not limited to, fasteners, welding, and crimping. In  FIG. 1  as shown, the second attachment member  14  may be secured to a frame whereas the first attachment member  12  may be secured to a pivotable access panel. The first attachment member  12  and the second attachment member  14  form a structure that provides access to a compartment when pivoted to an open position and denies access to the compartment when pivoted to a closed position. The access panels include, but are not limited to, a vehicle door, a tailgate of pickup truck, a trunk, an engine hood, or an interior compartment door such as a glove box. It should also be understood that the attachment members may also be non-automotive applications. 
         [0015]    The first attachment member  12  is attached and rotationally fixed to a first member  16  of the hinge assembly  10  that is radially spaced from a second member  18 . The first member  16  and the second member  18  are concentric with a pin member  20 . The pin member  20  constitutes a common axis between the first member  16  and the second member  18 . The pin member  20  is secured and rotationally fixed to the second attachment member  14 , which is fixed to a frame or similar structure. The second member  18  is fixed to the pin member  20 , which prevents rotational movement of the second member  18  relative to the second attachment member  14 . In this configuration, only the first member  16  and the first attachment member  12  rotate to pivot relative to the second attachment member  14  for allowing access to the compartment. 
         [0016]      FIG. 2  illustrates the cut away section of the hinge assembly  10 . The second member  18  is an inner core cylindrical-shaped member disposed radially interior of the first member  16 . The second member  18  includes a bore  22  for receiving the pin member  20  (shown in  FIG. 1 ) therethrough. The bore  22  serves as a common axis to both the first member  16  and the second member  18 . The second member  18  further includes a grooved section  24 . The grooved section  24  is preferably formed annularly around the outer circumferential surface of the second member  18 . The grooved section  24  retains a magnetic field generating member  26  such as a permanent magnet or an electromagnet. The function of the magnetic field generating member  26  will be discussed in detail later. 
         [0017]    The first member  16  is disposed radially from the second member  18 . An annular cavity  28  separates the first member  16  and the second member  18 . The annular cavity is filled with a magnetorheological (MR) fluid  30  thereby maintaining a spacing between the first member  16  and the second member  18 . Seals  32  and  34  are provided on the open ends of the annular cavity  28  for maintaining the MR fluid  30  within the annular cavity  28 . 
         [0018]    The MR fluid  30  is a mixture of solid magnetizable particles in a liquid medium, such as an oil, that when subjected to a magnetic field increases the viscoelastic properties of the fluid. The fluid can change from a fluid state to an elastic solid state. The yield stress or shear strength of the MR fluid  30  can be variably controlled by controlling the intensity of the magnetic field generated by the magnetic field generating member  26 . Magnetic particles that are suspended in the oil are randomly dispersed throughout the fluid when a magnetic field is not present. When a magnetic field is applied by the magnetic field generating member  26 , the magnetic particles align themselves and form chain-like structures in the direction of the magnetic flux. The stronger the magnetic filed the stronger the chain of particles. As a result, the various chains of particles formed therein between the first member  16  and the second member  18  resist the shearing of the fluid, thus resulting in an increase in the apparent viscosity of the fluid. As a result, the torque (i.e., shear strength) applied between the first member and the second member is controlled thereby controlling the ability to pivot the first member relative to the second member. Moreover, the pivoting member may be latched to a partial opened position as a limiting case, as opposed to a fully opened position. 
         [0019]    As described earlier, the magnetic field generating member  26  may include a permanent magnet having a predetermined strength. Alternatively, the magnetic field generating member  26  may include an electromagnet that is electrically controlled for varying the strength of the magnetic field applied to the MR fluid. For example, the current passing through the electromagnetic coil may be increased to maintain the hinge at a respective position when the hinge pivots to an open position and may be decreased to return the hinge to a closed position, or vice versa. To avoid the load on the power supply, the load could be reduced by using permanent magnets for activation of the MR fluid within the hinge and an electromagnet only when deactivation is required. In addition, the current may be increased variably that causes the hinge to stop pivoting at a respective position without utilizing a mechanical stop. Alternatively, the combination of the permanent magnet and an electromagnet may be used as a fail-safe condition for a power failure condition. Maintaining the device in an open position using an electromagnet could be susceptible to the device closing when not intended or desired. To avoid this occurrence, the hinge is maintained in a desired open position utilizing the permanent magnet. Since a permanent magnet maintains a constant magnetic field, the hinge would stay in the desired open position until an opposing torque overcomes the resistance torque due to the permanent magnet. By passing a know current through the electromagnet, its magnetic field could be used to overcome the field due to the permanent magnet and thus pivot the hinge back to the closed position. 
         [0020]      FIG. 3  illustrates the magnetic field generated by the magnetic field generating member  26 . The single member generates a magnetic field  31  that disperses partially into the MR fluid  30 . The strength of the field and the amount of the MR fluid  30  affected by the magnetic field determines the resistance torque between the first member  16  and the second member  18 . It should be understood that the magnetic field flux lines shown herein and throughout other embodiments described herein are provided for general illustrative purposes only and the flux lines may be different than what is shown. 
         [0021]      FIG. 4  illustrates a cut away section of a hinge assembly  40  according to a second preferred embodiment. The hinge assembly  40  includes a plurality of magnetic field generating members  42 ,  44 ,  46 . The plurality of magnetic field generating members provide an electromagnetic field to generate flow resistance in the MR fluid  30  for generating the desired torque for the hinge assembly  40 . It should also be understood that the plurality of magnetic field generating members  42 ,  44 ,  46  may be permanent magnets for applying a fixed magnetic field. Alternatively, the magnetic field generating members  42 ,  44 ,  46  may be electromagnetic members for generating an electromagnetic field as a result of an electrical charge applied to one or all of the magnetic field generating members  42 ,  44 ,  46 . The strength of the magnetic field may be varied by either varying the electrical charge applied or by selectively energizing respective magnetic field generating members  42 ,  44 ,  46 . Moreover, the plurality of magnetic field generating members  42 ,  44 ,  46  may be a combination of the permanent magnets and electromagnets. Electromagnets may be formed by a core center member having coils (e.g., radial windings) formed around the core center. 
         [0022]      FIG. 5  illustrates the magnetic field generated by the magnetic field generating members  42 ,  44 ,  46 . The plurality of magnetic field. The strength of the field and the amount of the MR fluid  30  affected by the each the magnetic fields generated by each of the magnetic field generating members  42 ,  44 ,  46  determines the resistance torque between the first member and the second member. 
         [0023]      FIG. 6  illustrates a cut away section of a hinge assembly  60  according to a third preferred embodiment. The hinge assembly  60  includes a first member  62  (e.g., outer sleeve) and a second member  64 . The second member  64  includes an inner core member and side disks that are affixed to the inner core. It should be understood that the inner core and the side disks may formed integral to one another. Seals  66  and  68  are provided on the open ends of an annular cavity  70  for maintaining MR fluid  30  within the annular cavity  70 . 
         [0024]    An electromagnet  72  is disposed radially outward from second member  64 . The electromagnetic field of the electromagnet  72  is controlled by energizing the electromagnet with an electrical charge. A permanent magnet  74  is disposed radially outward from the electromagnet  72 . As discussed earlier, the permanent magnet is utilized to increase the resistance of the MR fluid  30  within the annular cavity  70  when the hinge pivots to an open position. The electromagnet  72  is utilized to counter the effects of the permanent magnet  74  for decreasing the resistance of the MR fluid  30  when the hinge is required to pivot to a closed position. The combination of electromagnet  72  and the permanent magnet  74  is used as a fail-safe condition. 
         [0025]      FIG. 7   a - c  illustrates a cross section view of the hinge assembly illustrating various magnetic fields generated by the electromagnet  72  and the permanent magnet  74 . In  FIG. 7   a , no current is applied to the electromagnet  74 . As a result, the magnet field acting on the MR fluid is applied solely by the permanent magnet  74 . 
         [0026]    In  FIG. 7   b , a current is applied to the electromagnet  72  to generate a magnetic flux that cancels out the magnetic field generated by the permanent magnet  74 . As a result, no or a small magnetic field will be applied to the MR fluid  30 . Canceling out of the magnetic fields may be used when low torsional resistance is required or when the hinge assembly is to be pivoted to a closed position. This allows the hinge assembly to be effortlessly pivoted to a respective closed position. 
         [0027]    In  FIG. 7   c , a current is applied by the electromagnet  72  to generate a magnetic flux that cooperatively strengthens the magnetic field generated by the permanent magnet  74 . The magnetic field cooperatively applied by the electromagnet  72  and the permanent magnet  74  increases the torque resistance of the MR fluid  30 . The increased magnet field can be used when high torsional resistance is required to stop the hinge assembly at a desired pivoted location. 
         [0028]      FIG. 8  illustrates a cut away section of a hinge assembly  80  according to a fourth preferred embodiment. The hinge assembly  80  includes a first member  82  (e.g., outer sleeve ring) and a second member  84  (e.g., inner pin core). Seals  86  and  88  are provided on the open ends of an annular cavity  90  for maintaining MR fluid  30  within the annular cavity  90 . 
         [0029]    The second member  84  may be formed from a laminated core having a plurality of winding slots  92 . The plurality of winding slots extends axially along the laminated core. A plurality of axially wound coils  94  are formed in each of the winding slots. An electrical charge is applied to the plurality of the axially wound coils  94  for dynamically controlling the torque generated by the MR fluid  30  disposed within the annular cavity  90 . As a result, the movement of the hinge assembly may be dynamically controlled by the magnetic field generated by the electromagnetic coils. 
         [0030]    While certain embodiments of the present invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.