Abstract:
An actuation lever according is provided for a longitudinal adjustment device of a car seat, and includes, but is not limited to a gripping section, which a person uses to grab the actuation lever, and at least one attachment section for mechanically coupling the lever with a locking unit of the longitudinal adjustment device. The actuation lever is at least section ally, but preferably completely, made out of an injection molded plastic part.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to German Patent Application No. 102008061109.3, filed Dec. 9, 2008, which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present invention relates to an actuating lever for a longitudinal adjustment device of a motor vehicle, as well as to a corresponding longitudinal adjustment device, in particular for adjusting the position of the front seats in motor vehicles in the longitudinal direction of the vehicle. 
     BACKGROUND 
     Longitudinal adjustment devices are provided in nearly every motor vehicle, in particular for the front seats of passenger cars. The latter most often exhibit an upper rail connected with the car seat and a lower rail arranged on the vehicle body. When adjusting the car seat in the longitudinal direction of the vehicle, the upper rail on the seat side shifts relative to the lower rail. 
     The vehicle seat is kept in a predetermined position by means of a locking device, which prevents the upper rail and lower rail from shifting relative to each other. 
     In order to shift or adjust the vehicle seat in the longitudinal direction of the vehicle, it is provided that the locking device at least periodically allows a shifting of the upper rail and lower rail. To this end, a longitudinal adjustment typically exhibits an actuating lever that can be actuated by a vehicle passenger. Such actuation levers are typically situated under the vehicle seat, and can be gripped and actuated from the front by the vehicle passengers. 
     In particular by swiveling, but also by shifting the actuation lever, the lock between the upper rail and lower rail of the longitudinal adjustment device can be periodically released, thereby making it possible to shift the seat in the longitudinal direction of the vehicle. 
     The actuation levers previously used in prior art are made of a metal material, in particular a bent metal bracket, which is stiff enough to transfer the forces applied by the vehicle passengers to the locking device. 
     For example,  FIG. 1  shows an example of such a metal bracket of the kind used in prior art. The actuation lever  100  made entirely of metal exhibits a bracket-like geometry overall, with a gripping section  108  and two attachment sections  102 ,  104  provided at both of its ends. To establish an attachment to the longitudinal adjustment device or its locking device, both free ends of the actuation lever  100  exhibit an outer depression or receptacle  106  for a corresponding projection (not explicitly shown) of one locking unit  30  of the locking device. 
     Further, a respective depression or notch  110  is provided in proximity to the attachment sections  102 ,  104 , which comes to lie against the locking unit  30  between two fork-shaped attachment lugs  34 ,  36  with the actuation lever  100  assembled as shown on  FIG. 2 . 
     Such an actuation lever  100  does satisfy the prescribed mechanical load requirements. However, it is comparatively expensive to manufacture such actuation levers  100  made completely of metal. In addition, users perceive the haptic properties of such a metal bracket  100  as unpleasant owing to the often smooth and cold surface. 
     In view of the foregoing, at least one object of the invention is to provide an actuation lever for a longitudinal adjustment device of a car seat that can be produced more cost effectively and is easier to mount on a vehicle seat or its longitudinal adjustment device. In addition, the actuation lever is to exhibit haptic properties that are tangibly more pleasant to the user by comparison to an actuation lever made entirely of metal. In addition, other objects, desirable features, and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background. 
     SUMMARY 
     The at least one object, and other objects, desirable features and characteristics, is achieved with an actuation lever as well as a longitudinal adjustment device, and a vehicle seat. 
     The actuation lever according to an embodiment of the invention is provided for a longitudinal adjustment device of a car seat, and exhibits at least one gripping section, which a person uses to grab the lever. In addition, the actuation lever exhibits at least one attachment section for mechanically coupling the lever with a locking unit of the longitudinal adjustment device. The attachment section or gripping section is designed as an injection molded plastic part. 
     Designing at least portions of the actuation lever as an injection molded plastic part in this way makes it possible to correspondingly reject the use of metal material. This is accompanied by a savings in weight, along with a reduction in cost during the manufacture of the actuation lever. 
     The actuation lever designed only in portions as an injection molded plastic part can also easily satisfy all mechanical load requirements by continuing to fabricate precisely those sections of the actuation lever exposed to a correspondingly high load during actuation out of metal. 
     A first advantageous embodiment of the invention provides that both the gripping section and attachment section of the actuation lever be designed as an injection molded plastic part. Designing the gripping section as an injection molded plastic part makes it possible to provide haptics that are more pleasurable to the user by comparison to a metal lever. The outer shape of the gripping section can also be optimized to provide a pleasant and reliable gripping action, for example by furnishing a recessed grip. 
     Another especially advantageous embodiment of the invention provides that the entire actuation lever be designed as a one-part injection molded plastic part. This makes it possible to entirely forego the use of metal materials in manufacturing the actuation lever. The advantages relative to cost and weight savings are obvious. In addition, the plastic injection molding process establishes and sets the outer shape of the actuation level from the outset. As opposed to a using a metal pipe as the initial work piece, the component need not be subjected to any forming operations to achieve its prescribed outer shape. 
     In a further development of the invention, it is further provided that the injection molded plastic parts or entire actuation lever being designed as components that can be fabricated in an internal gas pressure injection molding process. During internal gas pressure injection molding, a gas is injected under a high pressure after the injection molding tool filling phase, in particular after reaching a predetermined partial filling of the cavity formed by the tool. The gas expels the free-flowing plastic, and fills the remainder of the tool cavity at pressures that can measure several 100 bar. 
     This expulsion produces hollow spaces in the injection molded component. The internal gas pressure injection molding process makes it possible to fabricate partially or entirely thick-walled injection molded parts that are devoid of sink marks and exhibit a sufficient surface quality. Shorter cycle times are achieve din the process, and material consumption is also reduced. In addition, the targeted formation of hollow spaces increases the stiffness of the injection molded part, and components of nearly any complexity can be generated in an especially streamlined manufacturing process. 
     As an alternative to the internal gas pressure process, it is further conceivable to manufacture the actuation lever using an internal water pressure injection molding process. 
     In a further embodiment of the invention, at least the gripping section of the actuation lever is provided with a hollow section in cross section. In addition, the attachment section can also exhibit an internal hollow space. Individual sections or the entire actuation lever can also be designed as a single or multi-component injection molded part. 
     The use of different plastics, preferably thermoplastics, duroplastics or elastomers, makes it possible to target prescribed stiffness and load requirements. 
     Another advantageous embodiment of the invention provides that at least the attachment section is fiber reinforced. The actuation lever here exhibits a fiber-reinforced plastic at least in its attachment section, but possibly also in its grip and any interspersed sections. Fiber-reinforcing materials include in particular fiberglass. Use can also be made in particular of materials like PA66-GF30 as the fiber-reinforced polyamide, at least in the attachment section. 
     One advantageous further development of the invention provides that at least the attachment section exhibits reinforcement ribs, which run inclined relative to the longitudinal extension of the attachment section. Such reinforcement or stiffening ribs increase the structural rigidity at least of the attachment section, so that the actuation lever made completely out of plastic can withstand the forces arising when actuating the lever. 
     It is here provided in particular that the reinforcement ribs form triangular or polygonal, in particular hexagonal, hollow spaces in cross section, possibly with one or two opposing exterior walls of the attachment section, wherein the hollow spaces extend essentially parallel to the swiveling movement of the actuation lever. The formation of triangular or hexagonal hollow spaces preferably extending perpendicular to the longitudinal extension of the attachment section can already provide sufficient structural stiffness owing to the shape of the attachment section, which can naturally be clearly increased even more through the use of fiber-reinforced plastics. 
     Another preferred embodiment of the invention provides that the attachment section exhibits at least two positive-fit elements spaced radially apart relative to a swiveling axis of the lever, which with the lever assembled on the longitudinal adjustment device interact with corresponding positive-fit elements of the locking unit to form a positive connection between the actuation lever and longitudinal adjustment device. The positive-fit elements provided for securing the actuation lever make it possible to attach the lever without using separate attachment means provided for this purpose, potentially even without the use of any tools. 
     For example, it is provided that the attachment section exhibits at least two receptacles spaced radially apart from each other for holding corresponding journals or brackets of the locking unit. The receptacles provided on the attachment section preferably extend perpendicular to the longitudinal extension of a leg of the actuation lever passing over into the attachment section. For example, it can be provided in particular that the receptacle and journals or brackets on the locking unit side that correspond therewith essentially extend in the transverse direction of the vehicle. 
     Providing at least two spaced-apart receptacles on the attachment section of the actuation lever is by no means compulsory. The present embodiments of the invention also allows for the reverse arrangement of corresponding positive-fit means, for example in the form of journals or brackets on the actuation lever side along with receptacles on the locking unit that correspond therewith. 
     It is additionally provided that the attachment section exhibits at least one flexible or elastically deformable or elastically deployable latching element, which at least sectionally grips an edge or hole border of the locking unit on the locking device with the actuation lever assembled. The latching element preferably designed as a latching nose helps to secure the assembly, preventing the remaining positive-fit elements of the attachment section and locking unit from spontaneously detaching from each other. 
     Another especially advantageous embodiment of the invention provides that the actuation lever be sectionally provided with stiffening or reinforcing elements, which connect spaced-apart sections of the actuation lever by way of struts. It is here in particular provided that these stiffening or reinforcing elements be connected as a single piece with the actuation lever, and exhibit a flat, plate-like outer contour. 
     It is provided in particular that the stiffening and reinforcing elements are used to reinforce or structurally stiffen a curved section of the actuation lever. In particular, a flatly designed stiffening or reinforcing element can lie in the plane that is clamped by the sections of the actuation lever that are connected by a curvature. The step of attaching or connecting the stiffening or reinforcing elements to the actual actuation lever is preferably incorporated into the injection molding process for forming the lever, thus eliminating the need for a separate work or assembly step for this purpose. 
     According to another independent aspect, the embodiments of invention further relates to a longitudinal adjustment device of a motor vehicle seat with an actuation lever according to the invention. The embodiments of the invention further encompass a car seat provided with such a longitudinal adjustment device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments of present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and: 
         FIG. 1  is a perspective view of an actuation lever according to prior art; 
         FIG. 2  is a magnified perspective view of the attachment section of the actuation lever according to  FIG. 1  connected with a locking unit; 
         FIG. 3  is a perspective view of the actuation lever according to an embodiment of the invention in the form of an injection molded plastic part; 
         FIG. 4  is a magnified view of the attachment section of the actuation lever according to  FIG. 3  connected with a locking unit; 
         FIG. 5  is another perspective view of the attachment shown on  FIG. 4 ; 
         FIG. 6  is a perspective, sectional view of a car seat provided with the actuation lever according to an embodiment of the invention, 
         FIG. 7  is a magnified perspective view of the attachment section of the actuation lever; and 
         FIG. 8  is a further perspective view of the attachment section according to  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit application and uses. Furthermore, there is no intention to be bound by any theory presented in the preceding background or summary or the following detailed description. 
     The actuation lever  10  according to an embodiment of the invention is shown in a perspective view on  FIG. 3  and exhibits a gripping section  12  in its upper (see  FIG. 3 ), central area lying to the front with the seat assembled as depicted on  FIG. 6 . The latter can be gripped by a user sitting in the vehicle seat  50 , so that the lever as a whole executes a swiveling motion about axis  15 , for example when pulling up on the gripping section  12 . As a result, the locking unit  30  connectable with the lever  10  can be switched to a release position, in which the vehicle seat  50  can be manually adjusted in the longitudinal direction by mutually shifting the upper rail  44  and lower rail  42  relative to each other. 
     The actuation lever  10  shown on  FIG. 3  is designed as a kind of bracket with lateral legs  11 ,  13 , which connects the gripping part  12  running essentially in the transverse direction of the vehicle at least sectionally with the attachment sections  14 ,  16  provided at the free ends of the bracket. 
     In the embodiment shown, the actuation lever  10  is designed as a one-piece injection molded plastic part. In particular using the internal gas pressure injection molding process makes it possible to easily achieve complex shape in the area of the attachment sections  14 ,  16 . The attachment section  14  positively connectable with the locking unit  30  exhibits a number of reinforcement ribs  28 , which on  FIGS. 4 and 5  form triangular hollow spaces when viewed from above. 
     These reinforcing or stiffening ribs  28  bring about a targeted, local increase in structural stiffness for the actuation lever  10 , in particular so as to be able to deflect and transfer those forces arising near a swiveling axis of the lever, without subjecting the lever itself to a deformation. The swiveling axis can here be preset by the locking unit  30 , for example by pivoting the locking unit  30  as such to the locking device of the upper and lower rails  44 ,  42  (not explicitly shown on the figures) so that it can swivel. 
     The attachment section  14  shown magnified on  FIG. 4  is further provided with several receptacles or through openings  22 ,  24 ,  26 , which are used to positively secure the attachment section  14  to the locking unit  30 . As depicted on  FIG. 2 , the locking unit  30  accommodates two inwardly projecting forked or pronged journals or attachment brackets  34 ,  36  on an end section facing the actuation lever  10 . 
     The latter come to lie in the through openings or receptacles  24 ,  26  provided on the corresponding attachment section  14  while assembling the actuation lever  10 . The receptacle  22  for holding a journal or bracket  32  essentially extending in the transverse direction of the vehicle and denoted by example on  FIG. 5  is also provided in corresponding fashion. Because the mutually corresponding receptacles  22 ,  24 ,  26  and journals  32 ,  34 ,  36  are spaced apart from each other, in particular radially spaced apart from each other relative to the swiveling axis of the locking unit  30 , an upwardly directed tensile force acting on the gripping section  12  is converted into a corresponding rotational or swiveling motion of the locking unit  30 . 
     The locking unit  30  is nearly unchanged relative to the configuration as described in prior art, e.g., as shown on  FIG. 2 . In particular, this makes it possible to smoothly change out the metal brackets according to prior art, e.g., as shown on  FIG. 1 , for the plastic brackets depicted on  FIG. 3 to 8 , and integrate the latter into day-to-day vehicle production. 
     The free ends of the attachment sections  14 ,  16  each exhibit outwardly projecting latching elements, which are designed to overlap an edge section of the locking unit  30 . To this end, the latching elements  38 ,  40  exhibit a stop incline and a latching groove lying behind that in the plug-on or slip-on direction, which is designed to reflect the material thickness of the locking unit, and provided to hold the locking unit  30 , which is preferably designed as a sheet section. 
     This latching connection is used to prevent the attachment section  14 ,  16  from spontaneously detaching from the accompanying locking unit  30 . The two latching elements  38 ,  40  form a positive fit acting at least in the transverse direction of the vehicle between the actuation lever  10  and the allocated locking unit of the locking device. 
     As depicted on  FIG. 3 , the latching elements  38 ,  40  (or projections) are arranged alternately on the upper and lower side of the attachment sections. While the latching element  38  arranged on the attachment section  14  envelops the allocated locking unit  30  from below, the latching element  40  arranged on the attachment section  16  is provided to envelop an allocated locking unit  30  (not explicitly shown on the figures) from above. 
     It can also be provided that both attachment sections  14 ,  16  are furnished with a respective upper and lower latching element or latching element  38 ,  40 . 
     It is also conceivable to arrange one or more latching projections or elements  38 ,  40  on the upper or lower side of an attachment section. 
     The latching connection of the actuation lever  10  on the adjustment device can further be designed in such a way that the actuation lever  10  releases from the adjustment device without unlocking the seat in the process in response to a force that exceeds the prescribed threshold, for example in a vehicle collision. 
     In order to attach the bracket  32  designed as an injection molded plastic part to opposing locking units  30  of the car seat, it is provided that the outer lateral surfaces of the attachment sections  14 ,  16  come to abut the inner surfaces of allocated locking units  30 . It can here be provided in particular that the distance between the opposing attachment sections  14 ,  16  of the actuation lever  10  be somewhat greater in the initial state, i.e., prior to assembly, than permitted by the clearance between the allocated locking units  30  of the locking device. 
     In this regard, it can be provided that the two opposing legs  11 ,  13  of the actuation lever  10  be moved at least slightly toward each other during assembly, so that the bracket-like, pre-stressed actuation lever  10  can be situated between locking units  30  opposing each other in the transverse direction of the vehicle. This outwardly directed pre-stressing of the actuation lever  10  counteracts a spontaneous detachment of the attachment sections  14 ,  16  of the actuation lever from the allocated locking units  30 . 
     In addition, the plastic actuation lever  10  designed as an injection molded part shown on  FIG. 3  exhibits structurally stiffening elements  18 ,  20  on its lateral legs  11 ,  13  that resemble flanges, e.g., are designed like a flashing. These stiffening or reinforcing elements  18 ,  20  are used for the targeted structural stiffening of the actuation lever  10 , in particular in such leg sections  11 ,  13  provided with a curvature. 
     The two essentially straight sections of the legs  11 ,  13  that abut the bend located in the middle of the legs  11 ,  13  or the curvature provided there are connected by way of a strut by means of the flat and plate-like stiffening and reinforcing elements  18 ,  20 . As a result, the forces to be transferred upon actuation of the lever can be reliably conveyed to the two attachment sections  13 ,  16  and introduced into the adjustment and locking device, while circumventing an extraordinarily high material load on the gripping section  12 . 
     The two stiffening or reinforcing elements  18 ,  20  are preferably attached in the injection molding process provided to form and shape the actuation lever  10 , thereby eliminating the need to subsequently stiffen the finished injection molded part. 
     While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.