Abstract:
A latch assembly is constructed from a plurality of modular sub-assemblies, such as a retention module sub-assembly, a release module sub-assembly, and an actuator module sub-assembly. Each of the sub-assemblies may incorporate various functional characteristics, such as motorized operation. Combining sub-assemblies having different functions allows construction of different latch assemblies while taking advantage of common sub-assembly parts, eliminating the need to construct completely new latch assembly designs to accommodate different functions.

Description:
REFERENCE TO RELATED APPLICATIONS  
         [0001]    The present invention claims priority to United Kingdom (GB) patent application number 0207525.7, filed Apr. 2, 2002.  
         TECHNICAL FIELD  
         [0002]    The present invention relates to vehicle latch assemblies, and more particularly to a vehicle latch assembly having modular components that can be used in latches having different specifications and/or functions.  
         BACKGROUND OF THE INVENTION  
         [0003]    Vehicle latches are used to releasably secure vehicle doors in a closed position. They are mounted in the vehicle door and include a retention plate having a mouth that receives a striker, which is usually formed as a fixed structure in the vehicle. The retention plate includes an upstanding claw pivot pin and an upstanding pawl pivot pin, both of which are in a fixed position relative to the retention plate. Some known latches also include a pawl that is rotatably fixed relative to a pawl pivot pin. In this type of latch structure, the pawl pivot pin is rotatable relative to the retention plate.  
           [0004]    The latch assembly also includes a rotatable claw pivotally mounted on the claw pivot pin. The rotatable claw has a claw mouth that can receive the striker. A pawl is pivotally mounted on the pawl pin and operably engages a first safety abutment or a closed abutment of the claw to retain the claw, and therefore the striker, in a first safety or fully closed position. The pawl can be rotated out of engagement with the claw, allowing the claw to rotate to its open position to release the striker and allow the door to open. The claw may be biased to its open position by a claw spring and the pawl may be biased to a claw engagement position by a pawl spring.  
           [0005]    Modern cars are designed with a passenger safety cell to protect the occupants of the vehicle if a traffic accident occurs. The proper operation of the safety cell relies significantly on the doors remaining closed. Components in the latch assembly, particularly the retention plate, claw, claw pin, pawl and pawl pin, must have sufficient strength to resist the high impact loads occurring during a traffic accident and prevent the door from bursting open.  
           [0006]    Latches on different vehicles and even different latches on one particular vehicle may have different security and operating modes. For example, a given latch may be openable by an inside door handle operation, openable by an outside door handle operation, lockable by an inside sill button operation, and lockable by an outside key barrel. Further, the operating modes of a given latch may include an unlocked mode, a locked mode (e.g., where operation of an outside door handle does not unlatch the latch but operation of an inside door handle does unlatch the latch), a superlocked mode (e.g., where any number of operations of an inside or an outside door handle, in any order, does not unlatch the latch), and a child safety mode (e.g., where operation of an inside door handle does not unlatch the latch, whereas operation of an outside door handle may or may not unlatch the latch depending upon whether the door is locked or unlocked).  
           [0007]    Moreover, a certain sequence of events can be used to perform desired functions. For example, an override unlocking function may be included in the latch assembly to prevent vehicle keys from being locked in the vehicle. In the override unlocking function, operation of an inside door handle may unlock the latch and unlatch the latch at the same time. When the door is subsequently closed, the door is unlocked and can therefore be opened by operation of the outside door handle. The override unlocking function is also useful to open a locked door during a child safety mode by allowing operation of an inside door handle to unlock the latch without unlatching the latch, enabling a subsequent operation of an outside door handle to conduct the actual unlatching process.  
           [0008]    The latch assembly may also be structured so that a sill button associated with certain types of latches, such as driver door latches, cannot be depressed when the door is open. This is also to prevent keys from being locked in the vehicle. In this type of structure, the only way to lock the latch from outside the vehicle is to close the door and insert a key into the key barrel of the latch assembly.  
           [0009]    The latch assembly may also be designed to require an outside door handle to be lifted when the door is in the open position before allowing the sill button to be pushed down to lock the door when the door is subsequently closed. Thus, the driver has to perform a specific sequence of events (i.e., lift the outside door handle and then depress the sill button) to lock the door. This design is also aimed to prevent keys from being locked in the vehicle.  
           [0010]    Thus, it can be seen that the mechanisms of the latch assembly itself, as opposed to devices remote from the latch assembly, can provide multiple lock operating modes and functions. Ultimately, whichever mechanism is used, the door will only open when the pawl is moved out of engagement from the claw. Thus, locking, superlocking, and child safety modes all relate to either providing a connection between the door handle and the pawl to move the pawl or breaking or blocking connection between the door handle and the pawl to prevent movement of the pawl.  
           [0011]    Vehicle door latches are typically mounted at the rear of a vehicle car door, while the pivot point of the vehicle door is typically mounted at a front edge. Further, an inside door handle is mounted on the inside of the door toward the door&#39;s front edge. Therefore, a connection mechanism is needed to connect the inside door handle with the door latch. Depending on the location of the inside door handle and the desired function of the connection mechanism with respect to the latch, different latches require different types of connection structures and orientations to be able to actuate the door latch. For example, some latching assemblies use the connection mechanism to simply provide unlatching of the door, whereas in other cases the connection mechanism provides both unlocking and unlatching of the door.  
           [0012]    To reduce costs, there is a desire to standardize latches fitted to the front and rear vehicle doors in a given vehicle and also standardize vehicle latches for different vehicle models. There is also a desire to standardize latch components for latches to be installed in different vehicle makes and models.  
         SUMMARY OF THE INVENTION  
         [0013]    The present invention is directed to a latch assembly having a retention module sub-assembly, a release module sub-assembly, and an actuator module sub-assembly. The retention module sub-assembly includes a retention plate having a mouth adapted to accept a striker, a claw that releasably retains a striker, and a pawl engageable with the claw to hold the claw so that it retains the striker. The release module sub-assembly includes a body, a pawl lifter that is rotatable to lift the pawl away from the claw so that the claw releases the striker. The actuator module sub-assembly includes a backplate and an inside release lever operable by an inside release handle to selectively move the pawl lifter.  
           [0014]    By creating separate, modular sub-assemblies, the invention allows manufacturing of latches having different specifications by simply changing sub-assemblies. For example, if two different vehicle manufacturers require two different latch functions (e.g., with and without manual override unlocking), the latch assemblies for both manufacturers may still contain the same retention module sub-assembly while incorporating different release module sub-assemblies (i.e. a manual override unlocking release module subassembly for one manufacturer and a powered override unlocking release module subassembly for another manufacturer). The invention allows replacement of only the relevant sub-assembly rather than requiring two completely different latch assembly designs to accommodate the different latch functions.  
           [0015]    Further, the release module sub-assembly can be produced according to different specifications (e.g., low line, medium line and high line), allowing for corresponding low line, medium line and high line latches to be manufactured by simply using different release module sub-assemblies rather than completely different latch assembly structures.  
           [0016]    Thus, the modular sub-assembly structure of the inventive latch assembly allows different combinations of modular sub-assemblies to be used depending upon the particular installation requirement of the latch assembly. For example, different modular sub-assembly combinations can be used for the front and rear doors of the same vehicle. Also different actuator module sub-assemblies can be used for different vehicle ranges for a particular vehicle manufacturer and also for different vehicle manufacturers. The invention therefore allows construction of latch assemblies having many different specifications from a limited number of modular sub-assemblies. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    The invention will now be described, by way of example only, with reference to the accompanying drawings in which:  
         [0018]    [0018]FIG. 1 is an isometric view of an actuator module sub-assembly of an embodiment of the present invention;  
         [0019]    [0019]FIG. 2 is an isometric view of a release module sub-assembly of an embodiment of the present invention;  
         [0020]    [0020]FIG. 3 is an isometric view of a retention module sub-assembly of an embodiment of the present invention;  
         [0021]    [0021]FIG. 4 is an isometric view of a latch assembly of an embodiment of the present invention;  
         [0022]    FIGS.  5  to  9  illustrate a method of assembling a latch according to an embodiment of the invention;  
         [0023]    FIGS.  10  to  15  illustrate specific components of latches according to embodiments of the present invention;  
         [0024]    [0024]FIGS. 16 and 17 illustrate schematic representations of two Bowden cables, of differing length, for use with latches according to an embodiment of the present invention.  
         [0025]    [0025]FIG. 18 is an isolated view of a lock link used in an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0026]    In this specification, similar components shown in different embodiments and different figures are labelled with the same reference number.  
         [0027]    [0027]FIG. 4 illustrates a latch assembly  10  containing modular sub-assemblies according to one embodiment of the invention. FIG. 3 illustrates a retention module sub-assembly  20  incorporated in the inventive latch assembly  10 . The retention module sub-assembly  20  includes a retention plate  22  having a mouth  24  for receiving a striker (not shown). The retention plate  22  includes a fixed claw pin  26 , which projects from the retention plate  22 . A fixed pawl pin  28  also projects from the retention plate  22 . The retention plate  22  includes mounting structures for attaching the latch assembly  10  to a vehicle door (not shown). In the embodiment shown in FIG. 3, the mounting structures are three threaded holes  25  through which screws are threaded to secure the latch assembly  10  to the door.  
         [0028]    The retention plate  22  has a first portion  23 A which is generally planar and includes the threaded holes  25 . The pawl and claw pins  28 ,  26  project from this first portion. Part of the first portion  23 A is also cut away to form part of the mouth  24 . The retention plate  22  also includes a second portion  23 B that also has a cutaway portion to form part of the mouth  24 . The second portion  23 B is positioned at substantially 90° relative to the first portion  23   a.    
         [0029]    The retention plate  22  may also have tabs  35  that are bent from the first portion  23 A and that are positioned at substantially 90° relative to the first portion  23 A. Each tab  35  includes a lug  36  at an end remote from the first portion  23 A.  
         [0030]    A claw  27  is rotatably mounted on the claw pin  26 . The claw  27  includes a mouth  27 A for releasably retaining the striker. The claw  27  further includes a first safety abutment  27 B and a closed abutment  27 C. A claw spring  30  biases the claw  27  to an open position.  
         [0031]    A pawl  29  is mounted on the pawl pin  28  and includes a pawl tooth  32  that engages with the first safety abutment  27 B or the closed abutment  27 C of the claw  27  to retain the claw  27  in the first safety position or the closed position, respectively. The retention module  20  further includes a pawl spring  34  that biases the pawl  29  into engagement with the claw  27 .  
         [0032]    The claw  27 , claw spring  30 , pawl  29  and pawl spring  34  are all fixed to the retention plate  22  to form a stable retention module sub-assembly  20 . The term “stable sub-assembly” is used throughout this detailed description to describe a sub-assembly where the components in the sub-assembly cannot fall off the sub-assembly regardless of the vibratory and gravitational forces on the sub-assembly during transit and regardless of the orientation of the sub-assembly.  
         [0033]    Referring to FIG. 2, the latch assembly  10  also includes a release module subassembly  40 . In one embodiment, the release module sub-assembly  40  is attached to the retention module sub-assembly  20  when forming the latch assembly  10 . The release module sub-assembly  40  includes a body  41 , a pawl lifter  43  (best seen in FIGS. 10 and 11), an outside release lever  44 , an outside release lever bias spring  44 A (best seen in FIG. 6), a lock link  45  (best seen in FIGS. 6 and 18), and a lock link lever  46 .  
         [0034]    In one embodiment, the body  41  is manufactured from injection-molded plastic and forms part of a housing for the various components of the latch assembly  10 . The body  41  may include a lock motor mounting  41 A and a superlock motor mounting  41 B. The body  41  may also include a boss  41 C (best seen in FIGS. 2 and 9) for receiving an outside release lever spring  44 A. Clips  41 D may also be provided to receive part of a key mechanism. A cylindrical boss  41 E (FIG. 6) is provided to receive a Bowden cable  75  or  76 , depending on the particular installation.  
         [0035]    A superlock motor  78  can be mounted in the superlock motor mounting  41 B. Selective operation of the superlock motor  78  will cause the latch assembly  10  to be superlocked or non-superlocked as desired.  
         [0036]    The pawl lifter  43  includes a generally cylindrical body portion  43 A having a central hole  43 B that fits over the pawl pin  28 . Two lugs  43 C project from the cylindrical body portion  43 A and engage the recesses  29 A of the pawl  29  to rotationally secure the pawl lifter  43 A with the pawl  29 .  
         [0037]    An arm  43 D projects tangentially from the body portion  43 A. Depending upon the particular embodiment, a resilient member (not shown) may act on the arm  43 D to bias the pawl lifter  43 , and therefore the pawl  29 , in a counter-clockwise direction when viewed from the perspective shown in FIG. 10. This resilient member can be used in place of the pawl spring  34  if desired.  
         [0038]    The pawl lifter  43  may also include an outside release abutment  43 E and an inside release abutment  43 F. The outside release abutment  43 E is acted upon by an outside release lever  44  and the inside release abutment  43 F is acted upon by the inside release lever  54 , as will be further described below.  
         [0039]    The outside release lever  44  (best seen in FIGS. 12 and 13) includes a hole  44 G that receives the pawl pin  29 . An abutment  44 B is provided for use in conjunction with the outside release abutment  43 E. A lug  44 C is engaged by a spring  44 A to bias the outside release lever  44  in a counter-clockwise direction when viewed from the perspective shown in FIG. 12. An end  44 E of the outside release lever  44  includes a fork  44 F that is engaged by a Bowden cable  75 A or  76 A, as will be described in further detail below.  
         [0040]    The lock link  45  includes an abutment  45 A that sits between the outside release abutment  43 E of the pawl lifter  43  and abutment  44 B of the outside release lever when the latch assembly  10  is in an unlocked condition. Thus, movement of the outside release lever  44  in a clockwise direction (when viewed from the perspective shown in FIG. 12) causes the abutment  44 B to engage the lock link abutment  45 A. This engagement causes the lock link abutment  45 A to also to move in a clockwise direction, thereby contacting and moving the outside release abutment  43 E of the pawl lifter  43  in a clockwise direction. The clockwise rotation of the pawl lifter  43  in turn moves the pawl  29  so that the pawl  29  disengages from the claw  27 .  
         [0041]    The end  45 B of the lock link  45  engages with a pin  46 A of the lock link lever  46 . The lock link lever  46  is pivotable around one end  46 B and can be moved in a counterclockwise direction (from the perspective shown in FIG. 6) by a lock motor  47  acting via a pinion  47 A (best seen in FIG. 7) on an array of teeth  46 C of the lock link lever  46 . Thus, in use, the lock motor  42  can be powered to move the lock link abutment  45 A between the abutment  44 B of the outside release lever and the outside release abutment  43 E of the pawl lifter  43  to unlock the latch. Alternatively, the lock motor  42  can be powered to withdraw the lock link abutment  45 A from the space between the abutment  44 B of the outside release lever and the outside release abutment  43 E to unlock the latch. The lock motor  42  may be configured to provide unlocking of the latch upon operation of an inside door handle (i.e., a power override unlocking function).  
         [0042]    It is also possible to lock the latch by using a key mechanism, which will be described in further detail below.  
         [0043]    The release module sub-assembly  40  may further include a power unlatching actuator (not shown), operable to power unlatch the latch. The release module subassembly  40  is a stable sub-assembly and is mounted onto the retention module subassembly  20  in a direction of arrow A shown in FIG. 3 such that the claw pin  26  and pawl pin  28  pass through the release module sub assembly  40 .  
         [0044]    [0044]FIG. 1 shows an actuator module sub-assembly  50  (also referred to as an inside release lever module sub-assembly, or backplate module sub-assembly) having a backplate  52 . Although the example described below assumes that the actuator module sub-assembly  50  corresponds with an inside release lever and an inside door handle, it can also be associated with other release levers and/or door handles without departing from the scope of the invention. The actuator module sub-assembly  50  is a stable subassembly. The backplate  52  includes holes  58  that accommodate the ends  26 A and  28 A of the claw pin  26  and pawl pin  28 , respectively (best seen in FIG. 7). The backplate  52  further includes rectangular holes  52 B through which the lugs  36  can pass. To secure the backplate  52  to the retention module sub-assembly  20 , the ends  26   a  and  28   a  are deformed to form rivet heads. The lugs  36  are similarly deformed to form a secure attachment structure.  
         [0045]    The backplate  52  includes a first portion  52 C that lies generally in the same plane as the first portion  23 A of the retention plate  23 . The first portion  52 C of the backplate includes holes  58  and rectangular holes  52 B. A second portion  52 D of the backplate  52  is bent at substantially  900  with respect to the first portion  52 C of the backplate. The second portion  52 D of the backplate  52  lies substantially parallel to the second portion  23 B of the retention plate  23 . The second portion  52 D includes a hole through which a pin  52 E is passed to secure an inside release lever  54 .  
         [0046]    The inside release lever  54  comprises a first part  54 A and a second part  54 B (best seen in FIGS. 14 and 15). The first part  54 A includes a hole  54 C for receiving the pin  52 E from the backplate  52 . A fork  54 D provides a connection with a Bowden cable inner cable. The first part  54 A also includes an L-shaped recess  54 E. The second part  54 B of the inside release lever includes a hole  54 F that receives the pin  52 E from the backplate  52 . The second part  54 B also includes an L-shaped recess  54 G. The inside release lever  54  also includes a pawl lifter abutment  54 H and an arm  541  having an override abutment  54 J. When assembled, the first and second parts  54 A and  54 B of the inside release lever  54  are both rotatably mounted on the pin  52 E of the backplate via the holes  54 C and  54 F. As such, regions B and C of the L-shaped recesses  54 E and  54 G are aligned. To provide child safety or superlocking functions, a pin (not shown) can be positioned in region B so that counter-clockwise movement of the first part  54 A does not cause movement of second part  54 B since the pin moves relative to the first and second parts to region D.  
         [0047]    When child safety function is off, or when the lock is not superlocked, the pin sits in region C. Thus, counter-clockwise movement of the first part  54 A of the inside release lever causes counter-clockwise movement of the second part  54 B since both parts are coupled together by the pin. Counter-clockwise movement of the second part  54 B causes pawl lifter abutment  54 H to engage and move the internal release abutment  43 F of the pawl lifter  43 . This causes the pawl lifter  43  to rotate in a clockwise direction (from the perspective shown in FIG. 10, thereby disengaging the pawl  29  from the claw  27  and allowing the latch to open.  
         [0048]    In a further embodiment, the second part  52 D of the backplate  52  can include an extension  52 F having a pin  52 G secured thereto. An override unlock lever  60  is pivotally mounted on the pin  52 G. An end  60 A of the override unlock lever  60  is engageable by an override abutment  54 J. Another end  60 B of the override unlock lever  60  is engageable with the lock link lever  46 . Counter-clockwise movement of the second part  54 B of the inside release lever causes counter-clockwise rotation of the override unlock lever  60  around the pivot  52 G. This in turn causes the second end  60 B of the lever  60  to engage with and move the lock link lever  46 , thereby unlocking the door.  
         [0049]    FIGS.  5  to  9  show the assembly sequence of a second embodiment of a latch. FIG. 5 shows the retention module sub-assembly  20 , FIG. 6 shows the release module sub-assembly  20  assembled onto the retention plate, FIG. 7 shows the latch assembly after the backplate  52  has been attached, and FIG. 8 shows the latch assembly after attachment of a key mechanism.  
         [0050]    Referring to FIG. 8, the key mechanism according to one embodiment of the invention includes a rod  65  that can be moved longitudinally by operation of a key. Drive power to the rod  65  comes via a key barrel mounted on the door and connected to a key mechanism barrel  64 . One end  65 A of the rod  65  is engaged in a slot  46 D of the lock link lever  46  (FIG. 6). Longitudinal movement of the rod  65  toward the left (from the perspective shown in FIG. 8) causes the lock link lever  46  to move so that the lock link abutment  45 A is withdrawn from the gap between the abutment  44 B on the outside release lever and the outside release abutment  43 E of the pawl lifter  43 , thereby locking the latch. Conversely, longitudinal movement of the rod  65  toward the right causes end  65 A of the rod to move to the other end of the slot  46 D in the lock link lever  46 , moving the lock link lever  46  so that the lock link abutment  45 A moves between abutments  44 B and  43 E, thereby unlocking the latch.  
         [0051]    As shown in FIG. 9, a cover  68  is then placed over the latch and secured. An outside release cable then can be inserted through a cylindrical boss  41 E such that the cable engages with the fork  44 F on the outside release lever  44 , thereby coupling the cable with the outside release lever  44 . A similar operation can connect an additional cable through boss  70  to the fork  54 D on the inside release lever. The orientation of the bosses  41 E and may be in any desired direction to provide any desired cable routing.  
         [0052]    It should be appreciated that different sub-assembly module structures and combinations can be provided, depending upon the particular requirements of a given latch assembly, without departing from the scope of the invention. For example, a pawl bias spring may be included on the retention module sub-assembly  20  (FIG. 3) or the release module sub-assembly  40 . A claw bias spring may also be included in the release module sub-assembly  40  or the retention module sub-assembly  40  (FIG. 3).  
         [0053]    Further, the release module sub assembly  40  may include a lock motor  42  that can either be fitted or non-fitted. When the motor  42  is not fitted, the lock link lever  46  can still be fitted, making the teeth  46 C of the lock link lever  46  redundant. A superlock motor (not shown) also may be included and may or may not be fitted to the superlock motor mounting  41 B. The latch assembly  10  may also have different bodies that may or may not include motor mountings  41 A, superlock motor mountings  41 B, or clips  41 D.  
         [0054]    The actuator module sub-assembly  50  can include a two-piece inside release lever  54  (FIG. 7) or a one-piece inside release lever. Note that if the inside release lever is a single piece, it is not possible to provide child safety or superlocking of the latch. Thus, such a latch would be used on a two-door car where superlocking is not required. The inside release lever may or may not include an override abutment  54 J. Further, the backplate  52  may or may not include an override unlocking lever  60 . In particular, it will be appreciated that a latch may not include an override unlock lever  60 , but may nevertheless include a redundant extension  52 F on the backplate  52  and a redundant override abutment  54 J on the inside release lever  54 .  
         [0055]    Thus, the varied features in the inventive latch assembly makes it possible to utilize these features in any combination while still allowing elimination of certain features for latches that do not require them. This allows the total part count of the latch to be minimized.  
         [0056]    Further, the modular sub-assemblies in the invention makes it possible to make different latch assemblies from the same collection of sub-assemblies. For example, a first latch assembly may comprises a retention module sub-assembly  20 , one form of release module sub-assembly  40  and the actuator module sub assembly  50  while a second latch assembly could comprise a retention module sub-assembly  20 , a different form of release module sub-assembly  40  and the actuator module sub-assembly  50 . Different latch assemblies may also be formed by using common retention module sub assemblies and release module sub assemblies, but different actuator module sub-assemblies.  
         [0057]    For example, the specification of a low-line latch assembly may call for manual release only, with no power release functionality. -The low-line specification might further call for a mechanical override unlocking mechanism (especially lever  60 ) as well as a mechanical connection to an outside key barrel (e.g., rod  65 ), without any power override unlocking or power locking. A medium-level latch assembly might also call for manual release, but provide a power actuator for override unlocking and regular locking/unlocking.  
         [0058]    A high-level latch assembly would include power release, power override unlocking and power locking/unlocking. The modular sub-assemblies provided in the inventive latch assembly allow each of these latch assemblies to be constructed by simply substituting different sub-assemblies without having to redesign the entire latch assembly.  
         [0059]    It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that the method and apparatus within the scope of these claims and their equivalents be covered thereby.