Abstract:
A directly coupled-inertia activated mechanism that may be incorporated into a door handle assembly and counteracts inadvertent door opening during a side crash. An inertia lever with certain inertia moment in relation ship to that of the handle is coupled to the handle, such that it rotates in the opposite direction of that of the handle when the handle is being pulled. The inertia lever is capable of canceling totally the inertia force causing the handle to move inadvertently to unlatched position during side impact crash, and stops the handle&#39;s unlatching move.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation of application Ser. No. 12/012,329, filed on Feb. 1, 2008, now abandoned. 
    
    
     FIELD OF INVENTION 
     The invention relates generally to the door release system of automotive vehicle, and in particular to a safety device in a door handle assembly as prevention of inadvertent opening of the door during crash, in particular side impact crash. 
     BACKGROUND OF THE INVENTION 
     Automotive vehicles can be involved in crash accident. In particular side crash can cause the handle to move inadvertently to unlatched position. Doors are unlatched and swung open, thus occupants are exposed to greater risk of being expelled from the vehicles. Many mandatory side crash tests are set up for vehicles. One requirement of these tests is that the vehicle doors remain closed during and after side crash test, in which the vehicle is hit from side. To measure side crash severity, acceleration in terms of G, (1 G=9.8 m/sec^2) is used. Very often, side crash is very severe that acceleration can be as high as 200 G in a very short of time interval. In side crash test, the acceleration is a spatial vector with lateral component parallel to the side impact, and vertical component perpendicular to the side impact. It is also a random time sequence, varies with the time. 
     Typically, a safety device against inadvertent move of the handle uses a counterweight mounted in the exterior handle assembly to reduce or to stop the handle move during side crash, because the counterweight&#39;s move under the inertia force makes the handle to move against the inertia force on the handle. One of the widely used design is to integrate counter weight into bell crank lever with a certain offset to the lever&#39;s pivot, such that the inertia force on the counter weight make the bell crank lever move against the handle&#39;s move under the inertia force. The bell crank lever transfers the handle&#39;s move and unlatches the latch. Or the counter weight can be a separate component, as described in the U.S. Pat. No. 7,070,216 B2. However, when the acceleration of the side crash is very high, e.g. 200 G, counterweight of suitable size fit into current automotive doors can not stop the handle from inadvertent move. Further when counterweight, which is integrated into the bell crank lever, is made large and heavy as required, it can easily overcome the spring bias and rotate to unlatch the latch under the vertical component of the inertia force, even that the exterior handle is not activated by the lateral component of the inertia force. 
     Additional components can be added to the door handle assembly as safety device, in which a component blocks the unlatching movement between the handle and the latch due to the inertia force, like the one mentioned in the U.S. Pat. No. 7,201,405 B2. However, it is highly possible and often the case that the handle already moves out passing a threshold and cause the latch to unlatch the door before this particular component begin to move as to block the handle&#39;s inadvertent movement. This is because that blocking component(s) and the handle have different dynamic behavior due to the acceleration nature of the side crash. Side crash has inertia force of spatial vector in orientation and random time sequence in magnitude. It is quite common that by the time a blocking component come into the engagement to block the unlatching movement, the component to be blocked/stopped has already gained some speed. The sudden block/stop induces very high stress on the blocking component and the one to be blocked, such that fatigue develops over the time. Eventually one or both of the components break. 
     SUMMARY OF THE INTERVENTION 
     The present invention is directed to a mechanism that counteracts inertia forces caused by a vehicle crash. The mechanism of the invention is also called directly coupled-inertia activated mechanism and may be incorporated into a door handle assembly of a vehicle. With one aspect of the invention, the directly coupled-inertia activated mechanism of the invention will compensate the inertia force on the door handle assembly, thus prevent the door handle assembly from unlatching the latch mechanism during a side crash. After the crash or when the crash force is removed, the directly coupled-inertia activated mechanism of the invention will allow the door handle assembly to function normally, thereby permitting the door to be opened and the occupants to exit from the vehicle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a door handle assembly incorporated with directly coupled-inertia activated mechanism according to an embodiment of the invention. 
         FIG. 2  is another perspective view of the door handle assembly of  FIG. 1 . 
         FIG. 3  is an exploded view of the door handle assembly of  FIG. 1 . 
         FIG. 4  is another exploded view of the door handle assembly of  FIG. 1 . 
         FIG. 5  is a side view of the door handle assembly of  FIG. 1 . 
         FIG. 6  is a perspective view of a handle with its features according to an embodiment of the invention. 
         FIG. 7  is a detail view of the handle of  FIG. 6 . 
         FIG. 8  is a perspective view of a chassis with its features according to an embodiment of the invention. 
         FIG. 9  is a perspective view of the chassis of  FIG. 8 . 
         FIG. 10  is a perspective view of the chassis of  FIG. 8 . 
         FIG. 11  is a perspective view of an inertia lever with its features according to one embodiment of the invention. 
         FIG. 12  is a perspective view of the inertia lever of  FIG. 11 . 
         FIG. 13  is a horizontal section along line F-F of  FIG. 5  showing coupling of the handle and the inertia lever according to the embodiment of the invention. 
         FIG. 14  is a top view of the door handle assembly with directly coupled-inertia activated mechanism showing resting position in solid lines, and unlatching position in dashed lines. 
         FIG. 15  is a top view of the door handle assembly showing the handle and the inertia lever being installed. 
         FIG. 16  is a top view of the handle. 
         FIG. 17  is a top view of the inertia lever. 
         FIG. 18  is a perspective view of the door handle assembly according to another embodiment of the invention. 
         FIG. 19  is another perspective view of the door handle assembly of  FIG. 18 . 
         FIG. 20  is an exploded view of the door handle assembly of  FIG. 18 . 
         FIG. 21  is a perspective view of a handle with its features according to another embodiment of the invention. 
         FIG. 22  is a perspective view of an inertia lever with its features according to the other embodiment of the invention. 
         FIG. 23  is a horizontal section along line F-F of  FIG. 5  showing coupling of the handle and the inertia lever according to the other embodiment of the invention. 
         FIG. 24  is a top view of the door handle assembly of  FIG. 18  showing the handle and the inertia lever being installed. 
         FIG. 25  is a top view of the handle. 
         FIG. 26  is a top view of the inertia lever. 
         FIG. 27  is a top view of the handle according to the other embodiment of the invention. 
         FIG. 28  is a top view of the handle according to the other embodiment of the invention. 
         FIG. 29  is a top view of the inertia lever according to the other embodiment of the invention. 
         FIG. 30  is a top view of the inertia lever according to the other embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIG. 1  and  FIG. 2  show a door handle system  101  of a vehicle. It is connected to a latch system (not shown) through a connecting element (not shown), usually a rod or a cable. The door handle system  101 , the latch system and the connecting element are installed in vehicle doors. The door handle system  101 , the latch system and the connecting element keeps vehicle doors closed, and let vehicle doors open when activated. Activating the door handle assembly  101  by pulling its handle will unlatch the latch system and the vehicle door is unlatched and open. 
     The door handle assembly  101  also inhibits inadvertent opening of the door  1  when the vehicle is involved in a collision, particularly an impact on a side of the vehicle which results in acceleration and/or forces in a lateral as well as in a vertical direction. 
     Referring  FIG. 1-4 , the door handle assembly  101  comprises a handle  3 , a chassis  4 , a latch activation mechanism  103 , an inertia lever  5  in one embodiment. The latch activation mechanism  103  comprises, but not limited to, a lever or bell crank lever named for distinguishing purpose, a spring or bell crank lever spring named for distinguishing purpose. 
     Referring to  FIG. 6 , the handle  3  has a body  7  for grabbing by hand. It has a tail  8  at a first end  9 , a hook  10  at a second, opposite end  11 , both extend from the same side of the body  7 . The centerline of the body  7 , the tail  8  and the hook  10  forms a plane A. On the tail  8  there are 2 notches, a notch  12  on the side  14 , a notch  13  on the side  15 . The two notches  12  and  13  are co-centered. The centerline A of the notches  12 ,  13  is perpendicular to the plane A. In one embodiment, there is a plurality of teeth  16  on the tail  18  about the centerline A in one embodiment ( FIG. 6 ,  FIG. 7 ). The plurality of teeth  16  is selectively at the side  18  of the tail  8 . The hook  12  takes a ‘L’ shape. 
     Referring to  FIG. 8 ,  FIG. 9  and  FIG. 10 , the chassis  4  takes a general rectangular shape from a view A, a ‘C’ shape from a view B, which is 90 degree to the view A. The face  20  on the end portion  21  and the face  22  on the opposite end portion  23  are parallel, particularly in the same plane B. When the door handle assembly is installed in the door  1 , the end portion  21  is towards rear and close to the shut face of the door  1 , and the face  21 ,  23  are fastened against the sheet metal of the door  1 . A plane C perpendicular to the plane B, parallel to one dimension L of the chassis  4  defines the center plane. There are an opening  24  in the end portion  21 , an opening  25  in the end portion  23 . The centerline of both openings lie in the plane C. The opening  25  has wall  26 ,  27 , which are parallel to the plane C, extended to the same side as the middle portion of the ‘C’ shape. On the wall  26  there is a post  28 ; on the wall  27  there is a post  29 . The post  28  and  29  are co-centered, and the centerline B of the post  28 ,  29  is perpendicular to the plane C. There is a ‘C’ shaped wall  30  on the opening  24 , more specifically on the end of the opening  24  towards the end  23 . The wall  30  extends to the same side as of the wall  26 ,  27 . The wall  31 ,  32  of the wall  30  are on the two opposite sides of the opening  24 , parallel to the plane C. When the handle  3  is installed in the chassis  4 , the tail  8  goes through the face  22  and the opening  25 , the hook  10  goes through the face  20  and the opening  24 . The notches  12 ,  13  are seated to the posts  28 ,  29 . After installation, the handle  3  can rotate about the centerline A between a rest position and a unlatch position with the hook  10  sliding between the wall  31 ,  32  ( FIG. 14 ). The hook  10  engages and activates the latch activation mechanism  103 , as understood by those skilled in the art ( FIG. 3  and  FIG. 4 ). 
     Referring to  FIG. 10 , there is a bracket  33  at the end of the end portion  23 , with a selective rectangular shape in one embodiment. One of its dimensions M is selectively perpendicular to the plane C. There are walls  34 ,  35 ,  36  on the bracket  33 , parallel to the plane C in general. The wall  34  is on one side of the plane C, the wall  36  is on the opposite side, both on the same side of the bracket  33 . There is a hole  37  on the wall  34 . There is a hole  38  on the wall  36 . The hole  37  and the hole  38  are co-centered, and the centerline C of the hole  37 ,  38  is perpendicular to the plane C. The wall  35  is between the wall  34  and  36 , close to the wall  36 , on the same side of the bracket  33  as the wall  34  and  36 . There is a notch  40  on the wall  35 , centered to the centerline C. The notch  40  is selectively opened in a direction perpendicular the plane B, towards the same side of the plane B as the wall  26 ,  27 . There is a chamfer  39  on the wall  36  towards the wall  35 , parallel to the dimension L. 
     When the handle  3  is installed onto the chassis  4 , the notches  12 ,  13  catch the posts  28 ,  29  of the chassis  4 , forming a pivot axis  69 . The centerline A and the centerline B overlap each other. Pivot axis  69  is in line with both the centerline A and the centerline B. Thus the handle  3  is pivotally supported on the chassis  4 , with the majority of it, including body  7 , appearing in the general area between the end portion  21  and the end portion  23  of the chassis  4  ( FIG. 3 ,  FIG. 4 ). This indicates that the center of mass  78  of the handle  3  is to the left of the pivot axle  69  ( FIG. 15 ). 
     Referring to  FIG. 11  and  FIG. 12 , the inertia lever  5  has a first ‘L’ shaped member  41 , with a selective extension  42  at the end  43  parallel to its main body  44 . It has a selective second ‘L,’ shaped member  45  with a main body  46  and an end  47 . The members  41  and  45  are connected together by a third member  48  on one side of the extension  42  and the same side of the end  47 . The main body  44  of the member  41  and the main body  46  of the member  45  are selectively in parallel to each other, both form a plane D. The member  48  has an ‘L’ shaped structure  49  at the end  50 , which connects to the end  47 . A forth member  51  of a selective ‘C’ shape joins the member  41  at a position  52 , the member  45  at a position  53 , on the same side as of the member  48 . The member  51  is selectively parallel to the member  48 . A selective triangular shaped post  64  stands out at the end  47 . A fifth member  54  with a selective circular shape in cross-section joins the member  41  at the extension  42 , with the centerline D parallel to the plane D, perpendicular to the main body  44  and  46 . The member  48  also joins the member  54  at a position  55  adjacent to its connection to the member  41  at the extension  42 . A cylindrical post  56  sits at an end  57  of the member  54 , next to the connection of the member  41  to the member  54 . A cylindrical post  58  sits at the end  59  of the member  54 , opposite to the end of  57 . The post  56  and  58  are co-centered, and centered to the centerline D. The post  55 ,  58  have smaller radius than that of the member  54 , thus their connection to the member  54  forms a shoulder  60  next to the post  56 , a shoulder  61  next to the post  58 . In one embodiment, the member  54  has a plurality of teeth  62  about the centerline D ( FIG. 9 ). The plurality of teeth  62  is selectively located, along the centerline D, closely to the member  41  in the area where the member  48  joins the member  54 ; and in a general area towards the member  41  and  45 . 
     When the inertia lever  5  is installed onto the chassis  4 , the posts  56 ,  58  are kept in the holes  37 ,  38  of the chassis respectively, forming a pivot axis  70 . The centerline C and the centerline D overlap each other. The pivot axis  70  is in line with both the centerline C and the centerline D. Thus the inertia lever  5  is pivotally supported on the chassis  4 , with the majority of it, including main body  44 ,  46 , appearing in the general area between the end portion  21  and the end portion  23  of the chassis  4 ( FIG. 3 ,  FIG. 4 ). This indicates that the center of mass  79  of the inertia lever  5  is to the left of the pivot axle  70  ( FIG. 15 ). 
     Since both the centerline B and the centerline C are perpendicular to the plane C, the centerline B and the centerline C are parallel to each other. Thus the pivot axle  69  and the pivot axle  70  are parallel to each other. 
     In one embodiment, the inertia lever  5  is installed onto the chassis  4  with its members  41 ,  45  towards the chassis  4  for its plurality of teeth  62  to engage the plurality teeth  16  on the handle  3  ( FIG. 2 ,  FIG. 3  and  FIG. 13 ). With the post  56  through the hole  37  and the pot  58  through the hole  38 , the inertia lever rotates about the pivot axle  70 . The shoulder  60  rests against the wall  34 , the shoulder  61  rests against the wall  36 . 
     The spring  6  is installed on the member  57 , with one of its leg  65  siting against the bracket  33  and the other leg  66  siting against the post  64  ( FIG. 2 ). The spring  6  provides bias to the inertia lever  5  to keep it, as well as the handle  3  to the rest position when the handle  3  is not pulled ( FIG. 14 ). 
     Referring to  FIG. 13 , after installation the plurality teeth  16  engage the plurality teeth  62 . In this fashion, the handle  3  and the inertia lever  5  are coupled with each other, e.g. pulling handle  3  will cause inertia lever  5  to rotate in the opposite direction to that of the handle  3 .  FIG. 14  shows that the inertia lever  5  rotates clockwise when the handle  3  is pulled and rotates counterclockwise. The plurality f teeth  16  and the plurality of teeth  62  are engaged with each other all the time, e.g. during normal operation of the handle assembly  101  and during side impact crash, thus the handle  3  and the inertia lever are directly coupled in one embodiment. It is appreciated that the coupling of the handle  3  to the inertia lever  5  may take different form than that of the plurality of teeth  16 ,  62 . It is also appreciated that the handle  3  may be fixedly assembled to a third component, the third component may be pivotally assembled to the chassis  4  and coupled to the inertia lever  5 . 
     Referring to  FIG. 16 , the side impact is represented by an acceleration a. The handle  3  is subjected to an inertia force G H  acting on the handle  3 &#39;s center of mass  78  due to its mass m H  and the acceleration a:
 
 G   H   =−m   H   *a,  
 
minus sign ‘−’ in front of m H *a indicates that the inertia force G H  is in opposite direction of the acceleration a.
 
     Referring to  FIG. 25 , the handle  3  being constrained by the pivot axle  69 , the inertia force G H  on the handle  3  is transformed into a force G H ′ acting at the location of the pivot axle  69  and a moment of momentum M H  about the pivot axle  69  per the shifting theorem of force:
 
 G   H   ′=−m   H   *a  
 
 M   H   =J   H *ε H .
 
J H  is defined as the handle  3 &#39;s inertia moment about the pivot axle  69 . The inertia moment of a rigid body about its pivot axle, e.g. handle, is associated with the rigid body&#39;s mass, size, and shape, and is calculated with the mathematical formula:
 
 J=∫r   2   *dm,  
 
dm is a small portion of mass of the rigid body
 
r is the distance from the pivot axle to the small portion of mass
 
∫ is integration operation.
 
ε H  is defined as the angular acceleration of the handle  3  about the pivot axle  69 .
 
     The moment M H  causes the handle  3  to rotate counterclockwise, and to rotate inadvertently to open position. 
     Referring to  FIG. 17 , the inertia lever  5  is also subjected to an inertia force G L  acting on the inertia lever  5 &#39;s center of mass  79  due to its mass m L  and the acceleration a:
 
 G   L   =−m   L   *a  
 
     Referring to  FIG. 26 , the inertia lever  5  being constrained by the pivot axle  70 , the inertia force G L  on the inertia lever is transformed into a force G L ′ acting at the location of the pivot axle  70  and a moment of momentum M L  about the pivot axle  70  per the shifting theorem of force:
 
 G   L   ′=−m   L   *a  
 
 M   L   =J   L *ε L .
 
J L  is defined as the inertia lever  5 &#39;s inertia moment about the pivot axle  70 . ε L  is defined as the angular acceleration of the inertia lever  5  about the pivot axle  70 . The moment M L  causes the inertia lever  5  to rotate counterclockwise.
 
     Referring to  FIGS. 13 and 25 , in the meshing of the plurality of teeth  16  and  62 , there is a contact point  80  between a tooth of the plurality of teeth  16  and a tooth of the plurality of teeth  62  at a particular moment of time. R1 is the distance from the contact point  80  to the pivot axle  69 , R2 is the distance from the contact  80  to the pivot axle  70 . At the contact point  80  at this moment of time, the tooth of the plurality of teeth  62  applies a force F L  on the tooth of the plurality of teeth  16  caused by the moment of momentum M L :
 
 F   L   =M   L   /R 2
 
The handle  3  being constrained by the pivot axle  69 , the force F L  is transformed into a moment M L ′:
 
 M   L   ′=F   L   *R 1 =M   L   *R 1 /R 2
 
M L ′ can be seen as the moment of momentum M L  being transferred on to the handle via the mesh of the plurality of teeth  16 ,  62 . The moment M L ′ causes the handle  3  to rotate clockwise.
 
     The resultant of the moments on the handle  3  is:
 
resultant= M   H   +M   L   ′ 
 
If the moment M L ′ is not parallel to the moment M H , its component which is parallel to the moment M H  will be used in the above calculation. Because M L ′ is opposite in direction to M H , then
 
resultant= M   H   +M   L   ′&lt;M   H  
 
Thus the resultant of the moments resultant is smaller than the moment M H . The effect of the resultant causing the handle  3  to rotate inadvertently to open position is reduced in comparison to that of the moment M H .
 
     Constructing the inertia lever  5  with selection of its mass, size, and shape in terms of its inertia moment, and particularly,
 
 J   L   =J   H *( R 2 /R 1) 2 ,
 
there is:
 
                   resultant   =       M   H     +     M   L   ′                   =       M   H     +       M   L     *     (     R   ⁢           ⁢     1   /   R     ⁢           ⁢   2     )                     =         J   H     *     ɛ   H       +       J   L     *     ɛ   L     *     (     R   ⁢           ⁢     1   /   R     ⁢           ⁢   2     )                     =         J   H     *     ɛ   H       +       J   H     *       (     R   ⁢           ⁢     2   /   R     ⁢           ⁢   1     )     2     *     ɛ   L     *     (     R   ⁢           ⁢     1   /   R     ⁢           ⁢   2     )                     =         J   H     *     ɛ   H       +       J   H     *     ɛ   J     *     (     R   ⁢           ⁢     2   /   R     ⁢           ⁢   1     )                     
Referring to  FIG. 13 , a linear acceleration a L  at the contact point  80  can be calculated with angular acceleration on each of the two meshing members and the distance from the contact point to the pivot axle of the respective meshing member:
 
 a   L   =R 1*ε H   ′=R 2*ε L ,
 
and
 
ε H ′=−ε H ,
 
then
 
                   resultant   =       M   H     +     M   L   ′                   =         J   H     *     ɛ   H       +       J   H     *     ɛ   H   ′                     =           J   H     *     ɛ   H       -       J   H     *     ɛ   H         =   0                 
The net effect of the resultant of the moments on the handle  3  is zero and the handle  3  does not rotate inadvertently to open position under the side impact.
 
     Without the need of large and heavy counter weight in the bell crank lever to counteract the inertia force on the handle, the bell crank lever being part of latch activation mechanism  103  in this case, the bell crank lever can be made with much less weight and stands little chance to rotate and unlatch the latch under the vertical component of the inertia force. 
       FIGS. 18-23  illustrate yet another embodiment for a directly coupled-inertia activated mechanism. 
     Referring to  FIG. 18 ,  FIG. 19 , and  FIG. 20 , the door handle assembly  102  comprises a handle  76 , a chassis  4 , a latch activation mechanism  103 , an inertia lever  77 , in one embodiment. 
     Referring to  FIG. 21 , a handle  76  has the same construction of the handle  3 . However, it does not have the plurality of teeth  16 , it has a slot  67  which can be an extension of the notch  12  and  13  of the handle  3  in another embodiment. 
     Referring to  FIG. 22 , an inertia lever  77  has the same construction of the inertia lever  5 . However, it does not have the plurality of teeth  62 , it has a post  68  connected to the member  54  in the other embodiment. 
     When the handle  76  is installed onto the chassis  4 , the notches  12 ,  13  catch the posts  28 ,  29  of the chassis  4 , forming a pivot axis  69 . The centerline A and the centerline B overlap each other. Pivot axis  69  is in line with both the centerline A and the centerline B. Thus the handle  76  is pivotally supported on the chassis  4 , with the body  7  appearing in the general area between the end portion  21  and the end portion  23  of the chassis  4  ( FIG. 20 ). This indicates that the center of mass  78  of the handle  76  is to the left of the pivot axle  69  ( FIG. 24 ). 
     When the inertia lever  77  is installed onto the chassis  4 , the posts  56 ,  58  are kept in the holes  37 ,  38  of the chassis respectively, forming a pivot axis  70 . The centerline C and the centerline D overlap each other. The pivot axis  70  is in line with both the centerline C and the centerline D. Thus the inertia lever  77  is pivotally supported on the chassis  4 , with the main body  44 ,  46  appearing in the general area between the end portion  21  and the end portion  23  of the chassis  4 ( FIG. 20 ). This indicates that the center of mass  79  of the inertia lever  77  is to the left of the pivot axle  70  ( FIG. 24 ). 
     Referring to  FIG. 23 , after installation, the slot  67  of the handle  76  engages the post  68  of the inertia lever  77 . In this fashion, the handle  76  and the inertia lever  77  are coupled with each other, e.g. pulling handle  76  will cause inertia lever  77  to rotate in the opposite direction to that of the handle  76 . The post  68  and the slot  67  are engaged with each all the time, e.g. during normal operation of the handle assembly  102  and during side impact crash, thus the handle  76  and the inertia lever are directly coupled in another embodiment. 
     Referring to  FIG. 27 , the side impact is represented by an acceleration a. The handle  76  is subjected to an inertia force G H  acting on the handle  76 &#39;s center of mass  78  due to its mass m H  and the acceleration a:
 
 G   H   =−m   H   *a,  
 
minus sign ‘−’ in front of m H *a indicates that the inertia force G H  is in opposite direction of the acceleration a.
 
     Referring to  FIG. 28 , the handle  76  being constrained by the pivot axle  69 , the inertia force G H  on the handle  76  is transformed into a force G H ′ acting at the location of the pivot axle  69  and a moment of momentum M H  about the pivot axle  69  per the shifting theorem of force:
 
 G   H   ′=−m   H   *a  
 
 M   H   =J   H *ε H .
 
J H  is defined as the handle  76 &#39;s inertia moment about the pivot axle  69 . ε H  is defined as the angular acceleration of the handle  76  about the pivot axle  69 .
 
     The moment M H  causes the handle  76  to rotate counterclockwise, and to rotate inadvertently to open position. 
     Referring to  FIG. 29 , the inertia lever  77  is also subjected to an inertia force G L  acting on the inertia lever  77 &#39;s center of mass  79  due to its mass m L  and the acceleration a:
 
 GL=−m   L   *a  
 
     Referring to  FIG. 30 , the inertia lever  77  being constrained by the pivot axle  70 , inertia force G L  on the inertia lever is transformed into a force G L ′ acting at the location of the pivot axle  70  and a moment of momentum M L  about the pivot axle  70  per the shifting theorem of force:
 
 G   L   ′=−m   L   *a  
 
 M   L   =J   L *ε L .
 
J L  is defined as the inertia lever  77 &#39;s inertia moment about the pivot axle  70 . ε L  is defined as the angular acceleration of the inertia lever  77  about the pivot axle  70 . The moment M L  causes the inertia lever  77  to rotate counterclockwise.
 
     Referring to  FIGS. 23 and 28 , in the meshing of the slot  67  and the post  68 , there is a contact point  81  between the slot  67  and the post  68  at a particular moment of time. R1 is the distance from the contact point  81  to the pivot axle  69 , R2 is the distance from the contact  81  to the pivot axle  70 . At the contact point  81  at this moment of time, the post  68  applies a force F L  on the slot  67  caused by the moment of momentum M L :
 
 F   L   =M   L   /R 2
 
The handle  76  being constrained by the pivot axle  69 , the force F L  is transformed into a moment M L ′:
 
 M   L   ′=F   L   *R 1= M   L   *R 1 /R 2
 
M L ′ can be seen as the moment of momentum M L  being transferred on to the handle  76  via the mesh of the slot  67  and the post  68 . The moment M L ′ causes the handle  76  to rotate clockwise.
 
     The resultant of the moments on the handle  76  is:
 
resultant= M   H   +M   L ′
 
If the moment M L ′ is not parallel to the moment M H , its component which is parallel to the moment M H  will be used in the above calculation. Because M L ′ is opposite in direction to M H , then
 
resultant= M   H   +M   L   ′&lt;M   H  
 
Thus the resultant of the moments resultant is smaller than the moment M H . The effect of the resultant causing the handle  76  to rotate inadvertently to open position is reduced in comparison to that of the moment M H .
 
     Constructing the inertia lever  77  with selection of its mass, size, and shape in terms of its inertia moment, and particularly,
 
 J   L   =J   H *( R 2 /R 1) 2 ,
 
there is:
 
                   resultant   =       M   H     +     M   L   ′                   =       M   H     +       M   L     *     (     R   ⁢           ⁢     1   /   R     ⁢           ⁢   2     )                     =         J   H     *     ɛ   H       +       J   L     *     ɛ   L     *     (     R   ⁢           ⁢     1   /   R     ⁢           ⁢   2     )                     =         J   H     *     ɛ   H       +       J   H     *       (     R   ⁢           ⁢     2   /   R     ⁢           ⁢   1     )     2     *     ɛ   L     *     (     R   ⁢           ⁢     1   /   R     ⁢           ⁢   2     )                     =         J   H     *     ɛ   H       +       J   H     *     ɛ   J     *     (     R   ⁢           ⁢     2   /   R     ⁢           ⁢   1     )                     
Referring to  FIG. 23 , a linear acceleration a L  at the contact point  81  can be calculated with angular acceleration on each of the two meshing members and the distance from the contact point to the pivot axle of the respective meshing member:
 
 a   L   =R 1*ε H   ′=R 2*ε L ,
 
and
 
ε H ′=−ε H ,
 
then
 
                     resultant   =       M   H     +           ML   ′           ⁢                       =         J   H     *     ɛ   H       +       J   H     *     ɛ   H   ′                     =           J   H     *     ɛ   H       -       J   H     *     ɛ   H         =   0                 
The net effect of the resultant of the moments on the handle  76  is zero and the handle  76  does not rotate inadvertently to open position under the side impact.