Patent Abstract:
A drive mechanism for a windshield wiper has wipe angle determined by the pivotable range of the pivot  16  which is driven by a motor  11  through gearbox  13 , crank  15 , connecting link  17  and a lever  18 . The connecting link  17  has more than one connection possibility as does the lever. The drivers  19  which connect the connecting link  17  to the crank  15  and lever  18  are eccentrically mounted so that changes in the wipe angle of the pivot  16  can be effected by changing the orientation of the drivers  19  and/or the attachment points between the connecting link  17  and the lever  18  and crank  15.

Full Description:
FIELD AND BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to windshield wipers and in particular, to a wiper mechanism for use in a single wiper unit.  
           [0002]    One disadvantage of currently available wipers is that each wiper mechanism is set to give a single wipe angle, i.e., the angle that the wiper arm is moved. However, each application for the wiper is different and these differences generally require that the wiper arm be moved a different amount, i.e., have a different wipe angle. This currently means that the wiper linkage mechanism has to be redesigned for each application resulting in the manufacturer having to make and store a large range of linkage parts even though the basic wiper unit is the same.  
           [0003]    Thus, there is a need for a linkage unit for a wiper mechanism which is flexible in assembly to enable different wipe angles to be achieved without using different parts. This can be achieved by varying the effective position of the drivers used to pivotally connect the linkage parts. The drivers are also known as ball joints and ball studs but are referred to herein as drivers.  
         SUMMARY OF THE INVENTION  
         [0004]    Accordingly, in one aspect thereof, the present invention provides a connecting link for use in a windshield wiper mechanism, the link having an elongate body with first and second ends, the first end having at least one socket for connection to a driver for pivotable connection to a first lever and the second end having at least two sockets for connecting to a driver for pivotable connection to a second lever wherein the effective length of the connecting link is changed by selecting various combinations of sockets at the first and second ends.  
           [0005]    Preferably, there is one socket at the first end and two sockets at the second end.  
           [0006]    Preferably, the sockets are holes in the body of the connecting link overmolded with plastic material to form a complementary bearing surface for the driver.  
           [0007]    According to a second aspect, the present invention also provides a windshield wiper mechanism comprising: a motor driving a crank through an output shaft; a pivot having a pivot lever and a first end adapted to receive a wiper arm, the pivot being arranged to drive the wiper arm in a back and forth motion, and a connecting link as defined in claim  1  wherein the connecting link is connected to the pivot lever by a lever driver received in a socket at one end of the connecting link and is connected to the crank by a crank driver received in a socket at the other end of the connecting link, whereby rotary motion of the crank causes oscillatory motion of the pivot through a predetermined wipe angle.  
           [0008]    Preferably, the lever and/or crank have a plurality of mounting positions for the driver giving various effective lengths of the lever and/or crank.  
           [0009]    Preferably, the driver is asymmetric with respect to means for connecting the driver to the lever an/or crank whereby relative orientation of the driver with respect to the lever and/or crank will vary the effective length thereof, thus varying the wipe angle.  
           [0010]    Other optional and preferred features of the invention are set forth in the dependent claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    One preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:  
         [0012]    [0012]FIG. 1 is a perspective view of a drive mechanism for a windshield wiper;  
         [0013]    [0013]FIG. 2 is a part perspective part exploded view showing a part of the drive mechanism of FIG. 1 with an adapter;  
         [0014]    [0014]FIG. 3 is a view of a connecting link used in the drive mechanism of FIG. 1;  
         [0015]    [0015]FIG. 4 is a perspective view of the drive mechanism of FIG. 1 in a different configuration;  
         [0016]    [0016]FIG. 5 is a perspective view of the drive mechanism of FIG. 1 in another configuration;  
         [0017]    [0017]FIG. 6 is an elevational view of a pivot arm as used in the drive mechanism of FIG. 1;  
         [0018]    [0018]FIG. 7 is an exploded view of the pivot arm of FIG. 6;  
         [0019]    [0019]FIG. 8 is a sectional view of an eccentric driver; and  
         [0020]    [0020]FIG. 9 is a plan view from below of the eccentric driver of FIG. 8. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]    [0021]FIG. 1 shows a drive mechanism  10  for a windshield wiper. The drive mechanism provides an oscillating pivot for driving or moving a wiper arm through a wipe angle, the predetermined angular range for wiping a windshield. The mechanism shown has a single pivot for driving a single wiper arm and therefore, is particularly suited for use in trucks and buses or other large vehicles with independent wipers or for use with rear windows.  
         [0022]    The drive mechanism  10  comprises an electric motor  11  driving an output shaft  12  through a gearbox  13 . The motor  11  and gearbox  13  are mounted on the back of a U-shaped bracket  14 . An offset lever or crank  15  is fixed to the output shaft  12  for rotation therewith. The crank  15  drives a pivot  16  in an oscillating motion through a connecting link  17  and a lever  18 . The effective lengths of the crank  15 , link  17  and lever  18  determine the angular oscillations of the pivot  16 . The connecting link  17  is pivotably connected to the crank  16  and lever  18  by drivers  19 . The lever  18  is fixed to the pivot  16  for rotational movement therewith. The pivot  16  is supported by a bearing  20  which is mounted to the U-shaped bracket  14  which is used to mount the wiper mechanism to a vehicle for use therewith.  
         [0023]    As shown in FIG. 2, the pivot  16  has a distal end  21  remote from the lever  18  to which the wiper arm is connected. The distal end  21  of the pivot has an internally threaded axial hole  22  for receiving a screw  23  for fixing the wiper arm thereto. The outer surface of the distal end  21  has a tapered knurled portion  24  forming a coupling surface dimensioned to mate with a DIN style mounting socket of a wiper arm.  
         [0024]    A ferrule  25  is provided for optional use to connect the pivot to a US style mounting socket of a wiper arm. The ferrule  25  has a through hole  26  with a tapered knurled inner surface (not shown) arranged to mate with the DIN style tapered knurled portion  24  of the pivot  16 . The outer surface  27  of the ferrule  25  is tapered and knurled according to US style wiper requirements. In use, the ferrule  25  is placed on the tapered portion  24  of the pivot  16  with the knurls meshed and a wiper arm with a US style mounting socket is placed onto the ferrule and the screw  23  placed through a hole in the wiper arm mount and the ferrule hole  26  and threadedly engages the hole  22  in the pivot  16 . The screw  23  is tightened so that a flange  28  on the head of the screw bears down on the wiper arm mount and maintains the wiper arm fixedly secured to the pivot via the ferrule.  
         [0025]    Wiper arms with DIN style mounting sockets are fitted in a similar way directly to the tapered knurled portion  24  of the pivot  16  without the use of the ferrule  25 . Use of the ferrule negates the need to manufacture and maintain separate wiper mechanisms for DIN style and US style wiper arms, thereby reducing inventory.  
         [0026]    Referring now to FIG. 3, the connecting link  17  is a generally elongated plate having a hole  29  at one end and two holes  30 ,  31  at the other end. Each hole has a plastic lining or grommet  32  providing a bearing interface between the connecting link  17  and the pivotable connection or driver  19  used to connect the connecting link  17  to the crank  15  and pivot lever  18 . The distance between holes  29  and  30  is less than the distance between the holes  29  and  31 . The grommets  32  may be molded directly to the link  17  in which case the grommets  32  for holes  30  and  31  may be integrally formed or joined together. The plate is preferably of an aluminum alloy material.  
         [0027]    As shown in the assembly figures (FIGS. 1, 4 and  5 ), the end of the connecting link with a single hole or first hole  29  is connected to the crank  15  via a first driver  19 . The other end of the connecting link  17  is connected to the pivot  16  via a second driver  19  attached to the lever  18  and coupled to one of the two available holes  30 ,  31  of the link.  
         [0028]    The second and third holes  30 ,  31  are formed or located at predetermined distances from the first hole  29  such that the first and second predetermined distances are not equal. In this embodiment, the first distance, the distance between the first hole  29  and the second hole  30  is 72 mm while the second predetermined distance, the distance between the first hole  29  and the third hole  31 , is 81 mm, center to center. Coupling the driver  19  on the lever  18  to the second hole  30  or the third hole  31  changes the effective or operational length of the connecting link  17  which in turn changes the wipe angle, i.e., the angular distance that one turn of the crank  15  will cause the pivot  16  to move.  
         [0029]    Thus, this one connecting link  17  now can provide the function of two separate connecting links. While a connecting link with three holes can provide two desired wipe angles, connecting links with more than three holes are possible, such as four holes (two at each end) (four separate distances) or three holes at one end and one hole at the other end (three separate distances) could be used.  
         [0030]    To increase the number of separate wipe angles, the pivot lever  18  is provided with a number of holes  33  for mounting of the driver  19 . In the preferred embodiment as illustrated, the lever  18  has three separate driver mounting holes  33 , each giving a different effective lever length (from pivot to driver), thus giving a different range of movement of the pivot when use with the second hole  30  or third hole  31  of the connecting link  17 . Thus, three different effective lever lengths with two different effective connecting link lengths give six different wipe angles. For example, these six wipe angles could be, say, 100°, 85°, 70°, 60°, 50°, 40°.  
         [0031]    As the drivers  19  are identical, only the driver connected to the pivot lever will be described in detail with reference to FIGS. 6 and 7. The driver  19  has a part spherical portion  34  which mates with the plastic liner  32  of the connecting link  17  and a base portion  35  which spaces the spherical portion  34  away from the lever  18 . The holes  29  in the lever  18  are hexagonal and receive a screw  36  with a hexagonal shank  37 . The driver  19  also has a hexagonal hole  38  for receiving the screw  36 . A nut  39  is threaded on the end of the screw  36  to fix the driver  19  to the lever  18 .  
         [0032]    To give even more variations to the effective lever length and crank length, the driver may have an offset or eccentricism as illustrated by the eccentric drivers of the preferred embodiments where the hole through the driver is offset from the central axis of the part spherical portion  34 . As the shank  37  of the screw  36  is hexagonal and the mounting hole  38  in the driver  19  is also hexagonal, the driver  19  can be positioned in one of six different orientations. By careful selection of the offset direction and the orientation of the hexagonal mounting holes  29  in the lever  18 , these six different orientations can give up to six different effective lever lengths or throws (distance from pivot center to driver center).  
         [0033]    Thus the throw will be varied depending on driver orientation and the amount of offset. With six possible positions on the lever driver and six positions on the crank driver giving 36 driver positions and with three lever lengths and two connecting link lengths as illustrated, a total of 216 different combinations are possible affecting the wipe angle of the pivot. However, some combinations may result in duplicate wipe angles. Even so, a typical combination may give 54 unique wipe angles ranging from 41° to 108°.  
         [0034]    Even with symmetrical alignment of the hexagonal mounting holes  29  and driver offset giving only three unique distance changes per driver, this still gives a large range of available wipe angles for vehicle manufacturers to select for their particular application from a single wiper mechanism. Thus this gives greater choice and freedom of design while reducing inventory.  
         [0035]    [0035]FIGS. 8 and 9 illustrate an alternative offset driver where the mounting hole and screw are replaced by an integral driver  119  in which a shaft  136  projects from the base portion  135  for mounting to the lever or crank. The shaft  126  engages a nut (not shown) to secure the driver  119  to the lever or crank and the shaft  136  has a hexagonal shank  137  for keying the driver  119  to the hexagonal holes in the lever or crank.  
         [0036]    A recess  140  is formed on the top of the driver  119  to form a reservoir for grease to lubricate the coupling.  
         [0037]    The embodiment described above is given by way of example only and various modifications will be apparent to persons skilled in the art without departing from the scope of the invention as defined in the appended claims.  
         [0038]    For example, it may not be necessary for an acceptable wiper model to include all of the features of the preferred embodiment such as the extra hole in the connecting link and in the lever or maybe to provide extra holes in the crank instead.  
         [0039]    Also, the driver or its mounting screw may have a shank which is not hexagonal in cross section, e.g. square giving up to four offset lengths or triangular giving up to only three offset lengths, etc.  
         [0040]    In an alternate embodiment of the driver, the fixing screw may have a non-circular shank, e.g., triangular, square, hexagonal, etc. and an offset threaded shaft portion which screws into or passes through a coaxial mounting hole in the driver. This allows for offset mounting of a standard driver.

Technology Classification (CPC): 5