Abstract:
A latch assembly for connecting a hood assembly to a truck includes a striker bolt that is surrounded by a sleeve that is engaged by a rotary latch. The sleeve is of shorter length than the striker bolt so that it can slide along the striker bolt. The rotary latch fixedly engages the sleeve so that any relative motion between the hood and frame translates to movement of the sleeve along the striker bolt rather than between the rotary latch and striker bolt. The sleeve arrangement thus provides wear protection to rotary latch, allows for self alignment of the hood and fender assembly along the striker bolt axis and dynamic movement of the latch during vehicle operation.

Description:
TECHNICAL FIELD  
       [0001]     The invention relates generally to the field of latches and more specifically to a latch striker assembly.  
       BACKGROUND OF THE INVENTION  
       [0002]     Heavy duty over the highway trucks are typically equipped with a single piece hood and fender assembly that pivots on hinges connected to the front of the frame rails. Many techniques are used for fixing the rear portion of the hood and fender assembly in the closed position. For example on some trucks simple elastomeric bands are stretched between the rear of the hood and fender assembly and the cab.  
         [0003]     U.S. Pat. Nos. 6,637,531 and 6,394,211 which are assigned to the assignee of the present invention, disclose a mounting system that uses latches mounted on struts connected to the frame rails to fix the rear portion of the hood and fender assembly in the closed position while isolating the hood and fender assembly from the operator cab. The system described in those patents addresses several problems associated with the connection between the hood and fender assembly and the truck. Flexure of the truck body that translates into movement of the hood and fender assembly can be transmitted to the operator cab causing vibration and noise. To mitigate the effects of hood and fender assembly movement on the cab, the patented system mounts the hood and fender assembly directly to the vehicle frame to isolate the cab from the hood and fender assembly.  
         [0004]     Another challenge related to the rear connection of the hood and fender assembly to the truck is that the connecting means needs to allow for variations in the position of the hood and fender assembly along the frame rails or with respect to the cab due to tolerance stack up, dynamic loading while the vehicle is in use, and also changes in hood and fender geometry as the assembly wears. This issue is addressed by the patented system by providing a conical shaped bracket that engages the latch pin and guides it into engagement with the keeper.  
       SUMMARY OF THE INVENTION  
       [0005]     A latch mechanism for connecting two vehicle panels features a bolt surrounded by a slidable sleeve that is engaged by a keeper mechanism. The sleeve is free to slide along the bolt after engagement by the keeper. This sliding arrangement reduces wear on the striker assembly, allows the panels to self align along the axis of the bolt, and allows for dynamic movement along the axis of the bolt during operation of the vehicle.  
         [0006]     According to one embodiment, a striker bolt is suspended at each of two distal end mounting points by mounting structure that defines a distance between the distal end mounting points. An outer sleeve loosely surrounds the striker bolt. The outer sleeve has a length less than the distance between the striker bolt distal end mounting points and the outer sleeve slidably engages the striker bolt such that the sleeve is free to slide along the length of the striker bolt between the distal end mounting points. A keeper assembly engages the outer sleeve to frictionally retain the outer sleeve in a fixed position relative to the keeper assembly.  
         [0007]     In an exemplary embodiment, an inner sleeve spans the distance between the striker bolt distal end mounting points to surround the striker bolt in a fixed position relative thereto. Accordingly, the outer sleeve loosely surrounds the inner sleeve such that the outer sleeve is free to slide along the length of the inner sleeve between the striker bolt distal end mounting points.  
         [0008]     According to a feature of one embodiment, the inner sleeve is made of a hardened steel. The outer sleeve may include a keeper retaining flange that prevents the keeper assembly from losing contact with the outer sleeve due to sliding motion. In an exemplary embodiment, the keeper assembly is a rotary latch that has a compliant sleeve engaging surface. According to one embodiment, the striker bolt is connected to a vehicle hood and fender assembly and the keeper is mounted to a vehicle frame. According to another embodiment, the striker bolt is connected to a vehicle hood and fender assembly and the keeper is mounted to a vehicle cab.  
         [0009]     These and other objects of the invention will become understood from a detailed description of an exemplary embodiment of the invention which is described in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a side view of a heavy duty truck that includes a latch mechanism in accordance with one embodiment of the present invention;  
         [0011]      FIG. 2  is a perspective view of the latch mechanism of  FIG. 1 ;  
         [0012]      FIG. 3  is an exploded view of the latch assembly shown in  FIG. 2 ;  
         [0013]      FIG. 4  is an exploded view of the latch striker assembly shown in  FIG. 2 ; and  
         [0014]      FIG. 5  is a cut away side view of an alternative embodiment of a latch mechanism according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]     Referring now to  FIG. 1 , a simplified cut away view of a front end  10  of a heavy duty over the highway truck is illustrated. An integral hood and fender assembly  12  pivots about the front most end of frame rails, one of which is shown  15 . The hood and fender assembly encloses the truck engine when in the closed position. The hood and fender assembly  12  is suitably held in the closed position by a pair of latches (only one shown) each having a striker assembly  30  connected to the hood and fender assembly and a rotary latch assembly  22  mounted on a mounting strut  47  that is connected to the frame rail  15 . It is contemplated that any suitable number of latches may be employed to hold the hood and fender assembly in position and therefore the use of two latches is for the purposes of this description only.  
         [0016]     An alternative embodiment is shown in  FIG. 5 , in which the rotary latch assembly  22  is mounted directly to an operator cab  19 . In this embodiment, the mounting bracket  24  is welded or bonded to the cab.  
         [0017]      FIG. 2  is a more detailed view of the latch  20  that holds the hood and fender assembly in the closed position. The latch  20  includes a rotary latch assembly indicated generally as  22 . The rotary latch assembly  22  has a mounting bracket  24  that is connected to the mounting strut  18  shown in  FIG. 1  or the cab  19  as shown in  FIG. 5 . A set of co-acting pawls (described in more detail below with reference to  FIG. 3 ) grip a slidable sleeve  34  on the striker assembly  30  to maintain the hood in the closed position. To release the latch, a release pawl  107  is rotated to release the latch&#39;s hold on the sleeve  34 . The release pawl is actuated by a cable  150  that is accessible to the operator as shown in  FIGS. 1 and 5 . When the cable is pulled the release pawl pivots, causing the rotary latch to disengage the sleeve  34 .  
         [0018]     The striker assembly  30  is mounted to the hood via a bracket  38 . The bracket features a mounting surface  37  that is formed between extending legs  31 ,  39  that include mounting holes at distal ends for a striker bolt  32  that is enveloped by the slidable sleeve  34 . The rotary latch assembly  22  engages the sleeve  34  at a point along its length. Once the rotary latch has engaged the sleeve, any relative motion between the hood and frame along the striker bolt axis is translated into sliding movement of the sleeve  34  along the bolt  32 . The maximum travel of the sleeve  34  is defined by the difference between the length of the sleeve and the distance spanned by the striker bolt  32  between the mounting legs  31 ,  39  (d 1  and d 2  in  FIG. 2 ). In one embodiment, the distance spanned by the striker bolt is 140 mm and the length of the sleeve is 115.4 mm. A raised lip  36  prevents the rotary latch assembly  22  from moving along the sleeve  34  to a point at which it is out of engagement with the sleeve. The striker assembly will be described in greater detail below in connection with  FIG. 4 .  
         [0019]     The rotary latch assembly  22  is a standard rotary latch that those of skill in the art will recognize. As such, most features of the rotary latch need no description herein, however a few components have been adapted to optimize the rotary latch for use with the striker assembly  30 .  FIG. 3  is an exploded view of the rotary latch assembly  22 . The rotary latch assembly is connected to the frame mounted strut or cab support structure with bracket  24 . A set of co acting pawls  109 ,  108 ,  107  move relative to one another against the force of biasing springs  105  in response to actuation of the release cable  150  that is supported by a release cable bracket  111  to release the striker assembly. Each pawl is located on the bracket  24  by a smaller diameter  103   b  of spacers  103  that are threaded onto bolts  101 . Washers  110  are also mounted on the bolts  101  to space the pawls apart from the release bracket. Nuts  112  are threaded onto the bolts to lock the bracket  24 , spacers  103 , pawls  107 ,  108 , 109 , washers  110 , and release bracket  111  into position.  
         [0020]     An assist spring  106  exerts a force tending to eject the striker assembly  30  from the rotary latch assembly  22  when the release mechanism is actuated. The release pawl  107  is moved by the release cable and acts upon the other pawls  108 ,  108  to create an opening large enough for the striker sleeve  34  to pass out of the rotary latch assembly  22 . The center spacer has an elastomeric washer  104  pressed around a large outer diameter  103   a . The outer diameter of this washer  104  compresses under the force of the striker assembly being contained between the latch pawls  108  and  109  when the hood is closed. While the hood is closed, the washer  104  creates a friction lock between the striker sleeve and the rotary latch. The friction lock essentially eliminates any relative motion between the rotary latch pawls  108 ,  109  and the striker sleeve, thereby reducing wear on the rotary latch pawls  108 ,  109 .  
         [0021]     The rotary latch  22  interacts with the striker assembly  30  to releasably retain the striker assembly.  FIG. 4  is an exploded view of the striker assembly  30 . The mounting bracket  38  includes the mounting surface  37  that connects to the hood. The bracket  38  has extending legs  31 ,  39  that include holes that accept the striker bolt  32 . In the described embodiment, the striker bolt has a hex shaped head and washer like flange  33  formed at one end. Alternatively, the striker bolt could be a rivet with a separate washer. The striker bolt  32  protrudes through the ears on the mounting bracket  37  and is held in place with a nut  40  that is threaded onto the end of the striker bolt. A spacer  35  closely surrounds the striker bolt  32  along the length of the striker bolt  32  that is located between the mounting ears. A sleeve  34  surrounds the spacer  35 . The sleeve is shorter than the spacer  35  to allow for dynamic movement of the rotary latch relative to the striker assembly  30 . The sleeve  34  is therefore rotatable and slideable relative to the spacer  35 , and the sleeve provides an outer surface that is adapted to allow the sleeve  34  to slide along its length. A raised lip  36  is formed on the striker sleeve  34  to prevent the pawls  108 ,  109  of the rotary latch do not slip of the striker  34  in the case of significant relative movement between the hood and the vehicle frame. The lip  36  is shown on one side of the striker sleeve  34 , however a similar lip may be formed on either or both sides of the striker sleeve as well depending on the application of the latch.  
         [0022]     Referring to  FIGS. 2-4 , The rotary latch  22  retains the striker sleeve  34  with no relative movement therebetween. The rotary latch  22  can engage the striker sleeve  34  at any location along its length, allowing for the variation in the relative position between the hood and the vehicle frame. Because the elastomeric washer  104  is the point of contact between the rotary latch  22  and the sleeve  34  rather than the pawls  107 ,  108 ,  109 , wear on the sleeve and pawls is reduced as well as noise. During vehicle operation, the striker sleeve  34  is free to slide along the spacer  35  to provide a movable connection between the hood and fender assembly without wear on the rotary latch components.  
         [0023]     Although the present invention has been described with a degree of particularity, it is the intent that the invention include all modifications and alterations from the disclosed design falling within the spirit or scope of the appended claims.