Patent Publication Number: US-9840857-B2

Title: Vehicle door latch

Description:
BACKGROUND 
     Exemplary embodiments of the present invention relate to door and movable panel latches and, more particularly, to door and movable panel latches for vehicles. 
     A vehicle frequently includes displaceable panels such as doors, hood, trunk lid, hatch and the like which are affixed for hinged or sliding engagement with a host vehicle body. Cooperating systems of latches and strikers are typically provided to ensure that such panels remain secured in their fully closed position when the panel is closed. 
     A door latch typically includes a forkbolt that is pivoted between an unlatched position and a primary latched position when the door is closed to latch the door in the closed position. The forkbolt is typically held in the primary latched position by a detent lever that pivots between an engaged position and a disengaged position. The detent lever holds the forkbolt in the primary latched position when in the engaged position and releases the forkbolt when in the disengaged position so that the door can be opened. 
     The forkbolt is pivoted to the primary latched position by a striker attached to, for example, an associated door jamb when the door is closed. Once in the primary latched position, the detent lever engages the forkbolt to ensure the assembly remains latched. 
     Latch sound quality can enhance or detract from the overall perception of quality by an end user about the construction of a vehicle. Good sound quality implies that the audible sounds shall convey solid construction, smooth operation, and thoughtfulness of design. The latch contributes to the abatement of noise and vibration, therefore, vehicle manufacturers are placing more emphasis on the ability of the door latch to absorb the noise emissions that may occur during a door closing event. Conventional door design places the door latch within the door cavity, and a striker mounted to the b-pillar of a vehicle. When the vehicle door is closed, the door latch first contacts the striker through the forkbolt lever, rotating it to a closed position. When rotated to this closed position, a second lever, the detent lever, rotates into position impeding the anti-rotation of the forkbolt, thus latching the door. These two levers are usually sandwiched between a steel structural frame plate and a plastic housing, and each pivot upon their respective steel pivots which are held fixed to the steel frame plate. During the latching event, the striker also contacts the striker guide usually integrated into the latch housing, and then the striker over-slam bumper, both of which serve to decelerate and dampen the kinetic energy of the swinging door. 
     Furthermore, the detent lever, which controls the position of the forkbolt lever, is spring loaded such that it will always return to a latched position. This spring torque creates a noise source due to the need of a stop to define a lever stop position. 
     Accordingly, it is desirable to provide a vehicle latch assembly that specifically address the aforementioned noise dampening methods in a unique manner that is superior to existing door latch designs. 
     SUMMARY OF THE INVENTION 
     In accordance with an exemplary embodiment of the invention, a vehicle latch assembly is provided. The latch assembly having: a fork bolt movably secured to the latch assembly, the fork bolt being capable of movement between a latched position and an unlatched position; a detent lever movably secured to the latch assembly, the detent lever being capable of movement between an engaged position and a disengaged position, the detent lever retains the fork bolt in the latched position when the detent lever is in the engaged position and a engagement surface of the detent lever contacts an engagement surface of the fork bolt; and a spring member integrally formed with the detent lever, the spring member being deflected by a bumper secured to the latch assembly when the detent lever is moved to the engaged position. 
     In accordance with another exemplary embodiment of the present invention, a method for absorbing stopping forces in a latch assembly, the method comprising: pivotally securing a forkbolt to the latch assembly for movement in a first plane between an unlatched position and a latched position; pivotally securing a detent lever to the latch assembly for movement in the first plane between an engaged position and a disengaged position wherein a contact surface of the detent lever engages a contact surface of the forkbolt when the detent lever is in the engaged position and the forkbolt is in the latched position; and adsorbing a stopping force of the detent lever by integrally molding a spring member to a surface of the detent lever, the spring member being capable of being deflected when the detent lever is in the engaged position and the spring member contacts a bumper secured to the latch assembly. 
     Additional features and advantages of the various aspects of exemplary embodiments of the present invention will become more readily apparent from the following detailed description in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view illustrating a latch assembly in a closed or primary latched position in accordance with an exemplary embodiment of the present invention; 
         FIGS. 2 and 3  are views illustrating an exemplary embodiment of the present invention and movement of the detent lever of the latch assembly; 
         FIGS. 4 and 5  are perspective views of a forkbolt in accordance with an exemplary embodiment of the present invention; 
         FIG. 6  is a perspective view of a portion of a latch assembly in accordance with an exemplary embodiment of the present invention; 
         FIG. 7  is a view along lines  7 - 7  of  FIG. 6 ; and 
         FIG. 8  is a perspective view of an exemplary embodiment of the present invention. 
     
    
    
     Although the drawings represent varied embodiments and features of the present invention, the drawings are not necessarily to scale and certain features may be exaggerated in order to illustrate and explain exemplary embodiments the present invention. The exemplification set forth herein illustrates several aspects of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Exemplary embodiments of the present invention relate to an apparatus and method for providing a latch assembly. Furthermore, exemplary embodiments are directed to a latch assembly having a forkbolt or forkbolt lever movably secured thereto for movement between a latched position and an unlatched position. The latch assembly further comprises a detent lever capable of movement between an engaged position and a disengaged position, wherein the detent lever retains the forkbolt in the latched position when the detent lever is in the engaged position. 
     In accordance with an exemplary embodiment of the present invention the detent lever of the latch assembly is provided with a spring member integrally formed with the detent lever, the spring member being deflected by a bumper secured to the latch assembly when the detent lever is moved to the engaged position. The spring member being capable of being deflected or deformed to adsorb or dampen a stopping force of the detent lever contacting the bumper such that the latch sound quality is improved in that abatement of noise and vibration is achieved through the deflection of the spring member. 
     In addition and in another embodiment, the forkbolt or forkbolt lever is also provided with a feature that adsorbs/dampens the stopping or closing forces of the forkbolt when it is transitioning into the closed position from the open position. Here the stopping forces are adsorbed by a feature located on a surface of the forkbolt that contacts an anti-bypass member such that the latch sound quality is improved in that abatement of noise and vibration is achieved through the braking forces applied by the feature contacting the ant-bypass member. 
     In addition, the distance between the feature of the forkbolt and a pivot point of the forkbolt is maximized such that a maximum stopping or braking force is applied thus further reducing noises associated with the closing forces. 
     Reference is made the following U.S. Pat. Nos. 6,811,193; 7,090,264; 5,520,426; 5,277,461; 5,316,354; 5,454,608; 4,969,673; 5,715,713; 5,535,607; 6,264,253; 6,749,234; and 6,733,052 the contents each of which are incorporated herein by reference thereto. 
     Referring now to  FIGS. 1-8 , a vehicle compartment latch or latch assembly  10  in accordance with an exemplary embodiment of the present invention is illustrated. In one embodiment, vehicle compartment latch  10  comprises a frame plate or support  12  that is adapted for fastening to a vehicle proximate to a compartment closure. 
     A forkbolt or forkbolt lever  16  is pivotally or rotationally mounted to frame plate  12  about a pivot pin or stud  18  that is received within a pivot pin opening of the forkbolt. Forkbolt  16  is capable of rotational or pivotal movement between an open or unlatched position and a closed or latched position shown in  FIGS. 1, 6 and 8 , wherein the forkbolt rotates in the direction of arrows  20 . 
     Vehicle compartment latch  10  is attached to a vehicle structure such that forkbolt  16  is moved between the open position and the closed position when a door, window, lift gate, etc. is opened and closed and forkbolt  16  engages a striker  22  (illustrated in cross section) that is attached to the door, window, lift gate, etc. Alternatively, the vehicle compartment latch  10  is secured to the door, window, lift gate, etc. and the striker is secured to the vehicle body at an opening into which the door, window, lift gate, etc. is received. The cooperation of a forkbolt and striker is well known and need not be described in detail. 
     Vehicle compartment latch  10  further comprises a detent lever  24  that pivots on support or frame plate  12  about a pivot pin  26  received within a pivot pin opening in the detent lever. The detent lever cooperates with forkbolt  16  in a well known manner to retain forkbolt  16  in the closed position shown in the FIGS. or release the forkbolt  16  for return to the open position. That is, detent lever  24  pivots between a closed or engaged detent position shown in the FIGS. and a release or disengaged detent position in the direction of arrows  28 . In accordance with an exemplary embodiment of the present invention, forkbolt  16  is spring biased to the open position by a biasing member (e.g., coil spring or other equivalent member) that has one end attached to forkbolt  16  and the other end attached to the housing or other equivalent location. Similarly, a biasing member or spring will also bias the detent lever in the direction of a face of forkbolt  16 . 
     In accordance with exemplary embodiments of the present invention, the forkbolt has an engagement surface or contact surface  30  that slides along and makes contact with a complimentary engagement surface or contact surface  32  of the detent lever when the forkbolt pivots or moves from the open position to the closed position and once in the closed position surface  30  of the forkbolt engages a surface  32  of the detent lever thus engaging the forkbolt and securing it into the closed position when the striker is secured in a receiving opening  38  of the forkbolt. Once the latch is in the closed position the detent lever is spring biased into contact with the forkbolt such that the forkbolt cannot rotate into the open position unless the detent lever is moved back to the release or disengaged detent position (e.g., moving surface  30  away from surface  32  allowing the forkbolt to rotate into the open position). 
       FIGS. 1 and 8  show structural components of a latch in a fully latched orientation. As seen, the detent lever is engaged on the primary tooth of the forkbolt lever, and each lever is capable of rotating about its respective pivot stud. The pivot studs are held mechanically fixed to the frame plate thus trapping their respective levers between the frame plate and a formed flange  40 ,  42  of the pivot studs. The pivot studs are dual supported opposite the frame plate by a back plate (not shown). 
     In accordance with an exemplary embodiment of the present invention, the detent lever makes contact with a bumper  44  when the detent lever is in the latched position see at least  FIGS. 3 and 8 . In one embodiment, the detent lever subassembly, see at least  FIGS. 2 and 3 , consists of a steel component  45  partially viewable at least at surface  32 , encapsulated with a thermoplastic elastomer or other equivalent material  46 . Integrated into the encapsulation of elastomer  46  is a flexible web feature or spring  48 . This flexible web feature assists in the deceleration of the detent lever when it returns via spring torque illustrated by arrow  50  to its latched position. As the detent lever reaches its stop position (e.g., contacting the bumper) the aforementioned web feature deforms until it reaches the maximum compression surface ( FIG. 3 ) which controls the latched position of the detent lever. In addition to the web feature integrated into the detent lever encapsulation, the detent lever return stop noise dampening is further enhanced by the elastomeric bumper  44 , which acts in series with the web feature. It is the combination of the two features that results in optimal noise suppression of the detent lever return stop sound. 
     As illustrated and in one embodiment, the integral web feature or spring is located at one end of the detent lever while the contact surface  32  is located at an opposite end. Of course, numerous other configurations are contemplated in order to provide for maximum noise suppression. 
     In one embodiment the bumper is secured to the frame plate and comprises an elastomeric coating or other equivalent material while the detent lever is formed from steel or any other suitable material and is coated with a thermoplastic elastomer such that the flexible web or integrally formed spring  48  is provided. As illustrated, the flexible web feature is spaced away from at least two peripheral surfaces  52 ,  54  of the encapsulated detent lever and the flexible web is capable of deforming or deflecting towards at least one of the surfaces when the web makes contact with the bumper  44 . It is, of course, understood that the elastomer or material comprising spring  48  can be spaced from only one or more than one (e.g., two, three or more) peripheral surfaces of the encapsulated detent lever and the elastomer or material comprising spring  48  will have resilient characteristics allowing it to deform and spring back to its un-deformed configuration in order to provide the desired dampening and noise abatement features. Although a specific configuration is illustrated and described, exemplary embodiments contemplate numerous configurations and the embodiments of the present invention are not intended to be limited to the specific configurations illustrated and described herein. 
       FIGS. 1 and 8  illustrate a preferred planar relationship between the forkbolt and the detent lever and a bite surface interface. In accordance with an exemplary embodiment,  FIGS. 6-8  illustrate a feature referred to as an anti-bypass member or an anti-bypass rivet  70 . As illustrated in  FIGS. 6-8 , the anti-bypass rivet comprises a steel member or any other suitable material is secured to the latch assembly by any suitable process (e.g., press fitting, welding, etc.) and is located in such a manner so as to not impede the rotation of the forkbolt and the detent lever under normal operation. 
     However, the anti-bypass member or an anti-bypass rivet prevents unwanted movement of the forkbolt and/or the detent lever. In order to do this the anti-bypass member or anti-bypass rivet has a head portion  72  that depends outwardly from a shaft portion  74  of the anti-bypass member or anti-bypass rivet. Furthermore, the head portion of the anti-bypass member or anti-bypass rivet is located and large enough to cover the bite surface interface of the forkbolt and detent lever. 
     In addition, the head portion of the anti-bypass member or anti-bypass rivet is located in a plane or second plane  76  that is parallel to a plane or first plane that the forkbolt and the detent lever rotate in. Accordingly, the anti-bypass member or anti-bypass rivet will allow for rotational movement of the forkbolt and the detent lever however, if their movement begins to move out of the plane they rotate in, the detent lever or the forkbolt or both with contact the anti-bypass member or anti-bypass rivet and preventing a by-pass condition wherein the forkbolt transitions to the open position when the detent lever is in the engaged position. 
     In addition, optimal overall door closing sound quality is further enhanced via an integrated braking feature  78  located on a surface of the forkbolt lever. The forkbolt lever subassembly,  FIGS. 4-8 , comprises of a steel component  80  that is encapsulated with a thermoplastic elastomer or other equivalent material  82 . Integrated into the encapsulation is a wedge feature  78 . As illustrated, wedge feature  78  is protrusion or other feature extending from component  80 . In one non-limiting embodiment, the feature has at least one inclined surface  79  for engaging the head member of the anti-bypass rivet or member. In other alternative embodiments, the feature can be configured to have multiple inclined surfaces some of which are located on opposite sides of the feature or in still another embodiment, the feature may be configured to not have any inclined surfaces. The effect of this feature is a rapid deceleration of the striker via the forkbolt/rivet head interface just prior to the forkbolt achieving its latched position. This rapid deceleration minimizes any oscillations the system may experience during closing and/or opening. This deceleration is accomplished by forcing the wedge feature under the flange  72  of the by-pass rivet that has been mechanically fastened to the frame of the latch assembly (further depicted in  FIG. 7  (cross section view)). The location of this rivet at the bite surface of the forkbolt and the detent lever allows for placement of the wedge feature to be at a maximum radial distance  84  from the pivot point of the forkbolt lever which provides maximum braking efficiency. 
     Accordingly, the condition created by the forkbolt lever wedging between two fixed surfaces and the web feature in series with the stop bumper at the detent lever makes this design exhibit superior door closing sound noise suppression. 
     As used herein, the terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another, and the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. In addition, it is noted that the terms “bottom” and “top” are used herein, unless otherwise noted, merely for convenience of description, and are not limited to any one position or spatial orientation. 
     The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., includes the degree of error associated with measurement of the particular quantity). 
     While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.