Patent Publication Number: US-2004045116-A1

Title: Windshield wiper having a single-rail spline

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] This invention relates generally to windshield wiper assemblies, and more particularly to a windshield wiper having a single-rail spline that improves the performance and decreases the manufacturing costs of the windshield wiper.  
       [0003] 2. Description of Related Art  
       [0004] A critical problem encountered by windshield wiper designers has been how to maintain contact between a wiper blade and a windshield at all times throughout the windshield wiping process. One complicating factor is that a particular wiper blade may be designed to fit on many different automobile models. Different automobiles typically have windshields of different sizes and shapes, and providing contact between the windshield and all parts of a wiper blade can be a difficult task. One design solution to the problem has been to provide wiper frames having spring-like flexural members attached to the frames. The flexural members exert forces at various points along the wiper blade to insure contact of the blade with the windshield.  
       [0005] The wiper blade portion of a windshield wiper assembly typically is made of an elastomeric material and includes a wiping portion and a head portion. The head portion of the wiper blade attaches to the frame of the wiper assembly, and it is typically desirable to include a stiffening member, which improves the connection between the wiper blade and the frame. The stiffening member, often referred to as a “spline,” adds rigidity to the head portion of the wiper blade, and helps insure that the wiper blade conforms to the curvature of the windshield.  
       [0006] Referring to FIG. 3 in the drawings, a cross-sectional view of a wiper blade  52  having a dual-rail spline  53  is illustrated. Wiper blade  52  includes a head portion  57  and a wiping portion  58 . Head portion  57  includes a top surface  59  and two side surfaces  61 . A groove  63  is disposed in each of side surfaces  61  for receiving dual-rail spline  53 . Dual-rail spline  53  is actually two individual, flat pieces of metal that add rigidity to head portion  57 . Dual-rail spline  53  is disposed within two separate grooves  63  on opposing sides of head portion  57 .  
       [0007] Wiper blade  52  is typically installed on a wiper frame using claws  65  that surround and grip an upper part of head portion  57  and dual-rail spline  53 . In order to prevent sliding of the wiper blade  52  within claws  65 , the claws  65  are crimped around head portion  57  at various points along the length of wiper blade  52 . One disadvantage of dual rail splines is that the crimping locally distorts the profile of wiping portion  58 , which reduces the performance of the wiper blade in the area surrounding the crimp.  
       [0008] The dual-rail spline also presents several disadvantages related to the costs of manufacturing and assembly. Since two separate splines are required, manufacturing costs are increased. A related cost increase is apparent in assembly, since it is more difficult and time consuming to install two flat splines in two separate grooves than it is to assemble a wiper assembly having fewer parts. In some dual-rail spline designs, a more complicated head portion is provided to prevent movement of the dual-rail splines relative to the wiper blade. Most of these designs require a molding process to manufacture the wiper blade, which is much more expensive than extrusion processes.  
       [0009] Another disadvantage is the higher likelihood of failure associated with two separate splines, as opposed to one integrated spline. Only one of the splines has to be broken, bent, or otherwise damaged to degrade the overall performance of the wiper. Additionally, if ice, snow, or sleet enters either of the grooves surrounding the spline, the flexibility of the wiper blade is decreased, which decreases the wiping ability of the wiper blade. Following installation of the wiper assembly on a vehicle, the upward facing groove on the dual-rail spline design is especially susceptible to ice, snow, or sleet penetration.  
       [0010] Referring to FIG. 4 in the drawings, another existing spline variation is illustrated. Wiper blade  71  includes a head portion  73  and a wiping portion  75 . A plastic spline  77  envelopes an upper part of the head portion  73  and fits into grooves  79  disposed on opposing sides of head portion  73 . The plastic spline  77 , like dual-rail spline  53  of FIG. 3, adds rigidity to the wiper blade  71 . Wiper blade  71  is attached to a wiper frame (not shown) using claws  81  that slidably grip the head portion  73  and plastic spline  77 . End caps (not shown) are typically installed at both ends of wiper blade  71  to prevent the wiper blade  71  from sliding out of claws  81 . Because of the use of the end caps, it is not necessary to crimp the claws  81  to wiper blade  71 . This prevents distortion of the wiper blade  71 , thereby allowing normal wiping performance.  
       [0011] Another plastic spline  85  is illustrated in FIG. 5. Similar to plastic spline  77  of FIG. 4, spline  85  surrounds a head portion  89  of wiper blade  87 . Plastic spline  85  is of unitary construction and has an “omega” shape. A claw  91  slidably grips plastic spline  85  and head portion  89  to attach wiper blade  87  to a wiper frame (not shown). End caps are installed on both ends of wiper blade  87  to prevent wiper blade  87  from becoming disengaged from claws  91 .  
       [0012] The primary disadvantage to plastic splines is the susceptibility of the plastic to deformation when exposed to extreme heat. Since wiper blades are often used on automobiles in hot climates, it is not desirable to have a spline material that is easily deformable. If the spline changes shape, the wiping portion of the wiper blade is subject to distortion, which decreases the wiping performance of the blade.  
       [0013] U.S. Pat. No. 5,893,193 describes a windshield wiper blade that includes a longitudinal conduit penetrating the length of the wiper blade. A runner-like spring element is housed within the longitudinal conduit which performs similar to a spline. The primary problem with this spline is that it is completely surrounded on all of its longitudinal sides by the elastomeric wiper blade. Consequently, the wiper blade must either be co-extruded with the spline or molded around the spline. Both of these manufacturing processes involve excessive costs. Additionally, this particular design requires that the wiper blade spring element be crimped by claws for attachment to the wiper frame. Crimping of the wiper blade prevents wiper blade replacement unless the entire wiper frame is also replaced.  
       [0014] A need exists, therefore, for a wiper having a spline that overcomes the problems presented by existing splines. Specifically, a spline is needed that is constructed of rugged material that is not susceptible to extreme changes in temperature. A spline is further needed that involves a minimal number of parts and that is easily incorporated with a wiper blade, thereby reducing the costs of manufacturing and assembly. The reduced number of parts should also provide fewer opportunities for spline failure, decreasing the likelihood of performance diminutions. A spline is further needed that, upon incorporation with the wiper assembly, is less susceptible to harsh weather conditions, especially snow, sleet, and ice. Finally, a spline is needed that does not require crimping of claws around the wiper blade for installation on the wiper frame. By eliminating crimping of the wiper blade, the performance of the wiper blade is improved, and the blade is easily replaceable.  
       BRIEF SUMMARY OF THE INVENTION  
       [0015] The problems presented by existing splines and wiper blades are solved by the present invention. A wiper blade having a wiping portion, a head portion, and a single-rail spline is provided. The head portion is connected to the wiping portion and includes a spline channel and a an entry slot, both the spline channel and the entry slot extending longitudinally along the head portion. The entry slot is adjacent to the spline channel, and preferably, at least one retention shoulder is disposed laterally adjacent to the entry slot.  
       [0016] When assembling the wiper blade, the single-rail spline is inserted through the entry slot and is received by the spline channel. The retention shoulders are elastically deformed to allow insertion of the single-rail spline, but the retention shoulders rebound to secure the spline within the spline channel.  
       [0017] A wiper assembly having a wiper frame, a wiper blade, and a single-rail spline is also provided by the present invention. The single-rail spline nests within a spline channel on the wiper blade and is secured by at least one retention shoulder disposed on the wiper blade. A frame attachment groove is disposed on the wiper blade to slidingly receive a plurality of blade-receiving members on the wiper frame.  
       [0018] The single-rail spline includes one of either a connection tab or a recess (or hole), and an end cap includes the other of either the connection tab or the recess. The end cap includes a projection member that is slidingly received by the frame attachment groove on the wiper blade. The end cap is releasably locked to the wiper blade and spline by the mating engagement of the tab and the recess, thereby preventing the wiper and spline from becoming disengaged from the blade-receiving members on the wiper frame.  
       [0019] Other objects, features, and advantages of the present invention will become apparent with reference to the drawings and detailed description that follow.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0020]FIG. 1 illustrates a front view of a wiper assembly according to the present invention, the wiper assembly including a wiper frame having a blade-receiving member, a wiper blade, a single-rail spline, and an end cap;  
     [0021]FIG. 2A depicts a perspective view of the wiper blade and single-rail spline of FIG. 1;  
     [0022]FIG. 2B illustrates a front view of the end cap of FIG. 1;  
     [0023]FIG. 2C depicts a top view of the end cap of FIG. 1;  
     [0024]FIG. 2D illustrates a side view of the end cap of FIG. 1;  
     [0025]FIG. 2E depicts a cross-sectional front view of the end cap of FIG. 1 taken at IIE-IIE in FIG. 2D.  
     [0026]FIG. 3 illustrates a cross-sectional side view of a prior art wiper blade having a dual-rail spline;  
     [0027]FIG. 4 depicts a cross-sectional side view of a prior art wiper blade having a conventional plastic spline; and  
     [0028]FIG. 5 illustrates a cross-sectional side view of a prior art wiper blade having an “omega” plastic spline.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0029] In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific preferred embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is understood that other embodiments may be utilized and that logical mechanical, structural, and chemical changes may be made without departing from the spirit or scope of the invention. To avoid detail not necessary to enable those skilled in the art to practice the invention, the description may omit certain information known to those skilled in the art. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims.  
     [0030] Referring to FIGS. 1 and 2A in the drawings, a wiper assembly  11  having a wiper frame  13 , a plurality of blade-receiving members  14 , a wiper blade  15 , and a single-rail spline  17  is illustrated. Wiper blade  15  and single-rail spline  17  are slidingly received by blade-receiving members  14  disposed on wiper frame  13 . Wiper frame  13  is of traditional design and includes a primary frame portion  19 , two secondary frame portions  21 , and a plurality of tertiary frame portions  23 . Secondary and tertiary frame portions  21 ,  23 , also referred to as “bridges,” are flexural members that help maintain contact between wiper blade  15  and a windshield (not shown). Secondary frame portions  21  are pivotally connected to both ends of primary frame portion  19 . Tertiary frame portions  23  are pivotally connected to each end of the secondary frame portions  21 . Together, the primary, secondary, and tertiary frame portions exert forces on multiple portions of wiper blade  15  so that the wiper blade  15  contacts, and thereby wipes, a windshield more effectively.  
     [0031] When installed on an automobile, airplane or other vehicle having a windshield, the primary frame portion  19  is pivotally connected to a wiper arm  25 . The wiper arm either rotates or translates relative to the windshield such that the wiper blade is dragged across the surface of the windshield. As the wiper blade moves across a windshield having a contour, the force exerted at the end of each frame portion (i.e. primary  19 , secondary  21 , or tertiary  23 ) coupled with the ability of each frame portion to pivot relative to the wiper arm and the other frame portions allows the wiper blade  15  to bend and conform to the shape of the windshield.  
     [0032] Although wiper blade  15  is designed to flex and conform to the shape of a contoured surface, it is preferred that wiper blade  15  retain some spring-like rigidity to oppose the forces imposed by the contoured surface, as well as the primary, secondary, and tertiary frame portions. The wiper blade rigidity further assists in providing full contact between the wiper blade  15  and the surface being wiped. Wiper blade  15  is combined with single-rail spline  17  to provide the required rigidity along the length of wiper blade  15 .  
     [0033] Referring more specifically to FIG. 2A, wiper blade  15  includes a head portion  29  and a wiping portion  31 . Head portion  29  includes an upper surface  33  having an entry slot  35 . A spline channel  37  is disposed within head portion  29  and is adjacent to and communicable with entry slot  35 . Preferably, both entry slot  35  and spline channel  37  extend the entire length of wiper blade  15  parallel to a longitudinal axis  38  of head portion  29 . In a preferred embodiment, entry slot  35  is not as wide as spline channel  37 , and a retention shoulder  39  is disposed on each side of entry slot  35 . Retention shoulder  39  is flexible, and is therefore configured to bend away from entry slot  35  while single-rail spline  17  is inserted into spline channel  37 . After spline  17  is seated within spline channel  37 , both retention shoulders  39  rebound to secure spline  17  within spline channel  37 .  
     [0034] A person having skill in the art will recognize that the presence of retention shoulder  39  is not absolutely necessary and that in such a scenario, entry slot  35  would be at least as wide as spline channel  37  and the spline  17  would most likely be secured by a friction fit between spline  17  and the walls of spline channel  37 . It is also conceivable that only one retention shoulder  39  is provided that extends from one side of head portion  15  and either partially or completely covers spline  17 . Finally, it is possible that entry slot  35  could be disposed on a surface of head portion  15  other than top surface  33 . For example, the entry slot  35  could be located on a side surface of head portion  15 , as long as the entry slot  35  is still communicable with and adjacent to spline channel  37 .  
     [0035] Head portion  15  also includes two frame attachment grooves  45  that extend the length of wiper blade  15 . Frame attachment grooves  45  are configured to slidingly receive blade-receiving members  14 . Blade-receiving members  14 , sometimes also referred to as “claws,” have protrusions that fit into grooves  45 . Although the blade-receiving members used with some wiper frames are crimped around the wiper blade, it is preferred in the present invention not to crimp the blade-receiving members  14 , but instead to allow the wiper blade  15  to slide within the protrusions. When slidingly installed on blade-receiving members  14 , the wiper blade  15  is further secured with a pair of end caps  47 . One end cap  47  is installed on each end of wiper blade  15  to prevent wiper blade  15  from sliding out of the grasp of the blade-receiving members  14 .  
     [0036] Referring still to FIG. 2A in the drawings, end cap  47  is only partially shown to better illustrate spline  17 . As seen in FIG. 2A, each end cap  47  preferably includes projection members  49  that are configured to slidingly engage frame attachment grooves  45 . A more complete illustration of end cap  47  is shown in FIGS.  2 B- 2 E. End cap  47  includes a lever member  48  having a connection tab  50 . Connection tab  50  is configured to engage a recess, or hole  51  disposed in each end of spline  17 . Preferably, the connection tab  50  is force-biased toward hole  51  by lever member  48  such that the connection tab engages hole  51  as the end cap  47  is slidingly received on the end of wiper blade  15 . Engagement of the connection tab by hole  51  prevents end cap  47  from sliding off the end of wiper blade  15 . Since an end cap  47  is installed on both ends of wiper blade  15 , the wiper blade is prevented from sliding out of the blade-receiving members  14 . The end cap  47  is configured to allow removal of connection tab  50  from hole  51  by applying an upward force to a removal end  52  of lever member  48 . This allows the end cap  47  to be removed from the wiper blade  15  so that wiper blade  15  can be replaced after becoming worn or damaged.  
     [0037] A person of ordinary skill in the art will recognize that while the preferred end cap  47  contains a connection tab  50  for engaging hole  51 , the end cap  47  could be configured with a hole or recess that receives a connection tab disposed on an end of the spline  17 . As in the preferred embodiment, the end cap  47  should be removable to allow replacement of wiper blade  15 .  
     [0038] Even though many of the examples discussed herein are applications of the wiper assembly having a single-rail spline that is one integral piece, it should be recognized that the single-rail spline could consist of two or more interlocking pieces that are placed within a spline channel on the wiper blade. It should also be noted that the single-rail spline, while preferably made of metal, could be constructed of any material that provides adequate resistance to heat and other extreme weather conditions. Finally, the single-rail spline and wiper blade of the present invention could be used in combination with any size or style of wiper frame.  
     [0039] From the foregoing, it will be recognized that the single-rail spline of the present invention provides a superior system for providing rigidity to a wiper blade, thereby allowing the wiper blade to fully contact a wiping surface for effective and efficient wiping. The single-rail spline is easily insertable through an entry slot in the head portion of the wiper blade and nests in a spline channel of the wiper blade. Since the spline is preferably made of a single piece of material and is manufactured separately from the wiper blade, the manufacturing costs and assembly costs are less than traditional designs using multiple splines or using splines that are co-extruded with the wiper blade.  
     [0040] The ability of the spline to engage an end cap provides additional advantages not seen in splines that are substantially covered by portions of the wiper blade. Since end caps are used with the spline and wiper blade of the present invention, the blade-receiving members do not have to be crimped to the wiper blade to secure the wiper blade to the wiper frame. Instead the wiper blade and spline are slidably received by the blade retaining members, which prevents performance degradation often seen with wiper blades that are crimped. The removable end caps also allow the wiper blades and splines to be replaced after experiencing wear or damage.  
     [0041] Still another advantage is provided by the retention shoulders disposed on the head portion of the wiper frame. The retention shoulders rebound after insertion of the single-rail spline in the spline channel and prevent the single-rail spline front becoming dislodged from the wiper blade. The retention shoulders also provide an effective barrier to ice, snow, and sleet that otherwise may penetrate the spline channel and degrade the performance of the wiper blade.  
     [0042] Finally, since the spline of the present invention is preferably made of metal, exposure to extreme temperatures does not inflict damage on the spline and subsequent performance loss on the wiper blade. This presents a substantial advantage over the use of plastic splines that often deform in extremely hot temperatures, thereby altering the profile of the wiper blade and decreasing wiper performance.  
     [0043] It should be apparent from the foregoing specification that an invention having significant advantages has been provided. While the invention is shown in only a few of its forms, it is not just limited but is susceptible to various changes and modifications without departing from the spirit thereof.