Windshieldwiperdrivelinkagearmwithgrooves.docx

1、WindshieldwiperdrivelinkagearmwithgroovesWindshield wiper drive linkage arm with groovesBACKGROUND OF THE INVENTION1. Field of the InventionThis invention relates to a windshield wiper system and, more particularly, to a windshield wiper system which utilizes at least one flexible member which bends

2、 or flexes to compensate for compression loads in excess of a predetermined load.2. Description of the Related ArtIn the field of windshield wiper systems, wiper arms having wiper blades thereon are driven from a park position, where the blades are often situated at either the bottom of or below a w

3、indshield of a vehicle, through an inwipe position, to an outwipe position. During normal wiping operations, the blades oscillate between the inwipe and outwipe positions to clean the windshield of debris or particles, such as ice, snow or other debris. It is not uncommon that snow or ice can accumu

4、late on the windshield and prevent the wiper blades from, for example, fully retracting from the inwipe position to the park position when a user actuates a wiper switch to an off position.When the debris blocks the wiper arms and blades, a considerable amount of stress is imparted on the wiper link

5、age and drive motor which drives the blades. For example, a motor drive link, which couples the drive shaft of the motor to the drive linkage which drives the wiper arms, often experiences a compressive force. The linkage members of the wiper systems have in the past been stiffened to reduce expansi

6、on and shrinkage in order to avoid changing the wipe pattern requirements for the vehicles. However, in freezing, snowy weather, the snow and ice packs at the bottom of the windshield causes a restriction in the movement in the wiper arm and blade. Because of the rigidity of the motor drive link, th

7、e housing which houses the drive gears of the drive motor may crack or break. It has also been experienced that one or more drive plates which directly or indirectly couple the drive link to other linkage have been known to fracture or crack.U.S. Pat. Nos. 6,148,470 and 6,381,800 illustrate a compos

8、ite arm, which are incorporated herein by reference and made a part hereof. Benefits of those inventions are taught in the article “A Novel Use of a Composite Material to Limit the Loads in Windshield Wiper Systems”, Penrod, et al., Copyright 2001 Society of Automotive Engineers, Inc., which is inco

9、rporated herein by reference and made a part hereof.Accordingly, what is needed is a simple, yet effective, linkage system which utilizes one or more linkage arms having a relatively low modulus of elasticity with relatively high elongation and fatigue properties to facilitate avoiding the problems

10、of the past.SUMMARY OF THE INVENTIONIn one aspect, this invention comprises a windshield wiper drive linkage for use in a wiper system comprising a plurality of linkage arms, at least one of said plurality of linkage arms comprising a composite flexible arm which bends to facilitate preventing damag

11、e to components in the wiper system when a compressive load applied to at least one of the plurality of linkage arms exceeds a predetermined load as a result of a fatigue condition, the at least one of said plurality of linkage arms comprising a plurality of grooves on each end to facilitate providi

12、ng an interlocking joint when a connector is overmolded onto each end.In another aspect, this invention comprises a wiper system comprising a first wiper, a second wiper, a windshield wiper drive linkage coupled to said first and second wipers, a drive motor coupled to the windshield wiper drive lin

13、kage; and the windshield wiper drive linkage comprising a plurality of linkage arms coupled to the first and second wipers and the drive motor, at least one of the plurality of linkage arms comprising a composite flexible arm which bends to facilitate preventing damage to components in the wiper sys

14、tem when a compressive load applied to the at least one of the plurality of linkage arms exceeds a predetermined load as a result of a fatigue condition, the at least one of the plurality of linkage arms comprising a plurality of grooves on each end to facilitate providing an interlocking joint when

15、 a connector is overmolded onto each end.Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings, and the appended claims.BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGSFIG. 1 is a general schematic view of a wiper blade drive and linking s

16、ystem in accordance with one embodiment of the invention;FIGS. 2A2D are illustrations of the wiper blade assembly of FIG. 1 as it is driven from an outwipe position towards inwipe and park positions;FIG. 3 is a perspective view of a flexible member in accordance with one embodiment of the invention;

17、FIG. 4 is a front view of the flexible member shown in FIG. 3;FIG. 5 is a plan view of the flexible member shown in FIG. 3;FIG. 6 is a fragmentary sectional view of an end cap situated on the flexible member;FIG. 7 is a view similar to FIG. 6 showing a plurality of shear areas to enable the cap to s

18、eparate from the flexible member when a shear stress exceeds a predetermined amount;FIG. 8A is a sectional view taken along the line 8A8A in FIG. 6;FIG. 8B is a sectional view similar to FIG. 8A showing a flexible member with rounded corners;FIG. 9 is graphical representation of a relationship betwe

19、en a compressive load for the flexible member relative to the length of the member as it shortens and flexes when the compression load exceeds a predetermined amount;FIG. 10 is an illustration of another flexible member in accordance with another embodiment of the invention;FIG. 11 is a illustration

20、 of the flexible member shown in FIG. 10 showing a shortened length L4;FIG. 12 is a sectional view taken along the line 1212 in FIG. 10;FIG. 13 is a sectional view taken along the line 1313 in FIG. 11;FIG. 14 is a detailed drawing of a flexible arm;FIGS. 15A and 15B are drawings of first and second

21、ends respectively of a flexible arm;FIG. 16 is a drawing of a flexible arm looking in the direction 1616 of FIG. 14,FIG. 17 is a side view of a composite link socket attachment;FIG. 18 is a plan view of a composite link socket attachment;FIG. 19 is a perspective view of another embodiment of the inv

22、ention;FIG. 20A and FIG. 20B illustrate another embodiment of the invention;FIGS. 21A and 21B illustrate load characteristics of the invention;FIG. 22 is a view illustrating another test;FIG. 23 is a graph illustrating various features of the invention; andFIG. 24 is another graph illustrating furth

23、er load characteristics of the invention.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTSReferring now to FIGS. 1 and 2A2D, a windshield wiper system 10 is shown comprising a first wiper 12 and a second wiper 14 for wiping a windshield 16. The wiper 12 comprises a wiper arm 12a and blade 12b, and w

24、iper 14 comprises a wiper arm 14a and blade 14b. The wiper system 10 further comprises a windshield wiper drive linkage or linking means 18 comprising a first link arm 18 on which a drive motor 20 is fastened thereto by conventional means, such as a weld, nut and bolt, or the like. Notice that the f

25、rame link 18 comprises a first pivot housing 21 and a second pivot housing 22 which is secured thereto. The housings 21 and 22 comprise a first rotatable pivot housing shaft 21a and a second rotatable pivot housing shaft 22a which are drivingly coupled to wiper arms 12a and 14a (shown in phantom in

26、FIG. 1), respectively.The first rotatable pivot housing shafts 21a is coupled to a first end 24a of a drive plate 24. Likewise, the pivot housing shaft 22a is secured to a first end 26a of a second drive plate 26, as best illustrated in FIG. 1. An operating or “slave” link 23 couples a second end 24

27、b of first drive plate 24 to a second end 26b of second drive plate 26 such that the drive plates 24 and 26 operate synchronously to rotatably drive the pivot housing shafts 21a and 22a in the direction of arrow A, thereby driving the wiper blades 12b and 14b. The linkage or linking means 18 further

28、 comprises a motor drive link or flexible arm 28 having a first end 28a coupled to the second end 24b of the drive plate 24. The motor drive link or flexible arm 28 further comprises a second end 28b which is coupled to an output shaft 20a of motor 20 via a crank arm 30. In this regard, the crank ar

29、m 30 comprises a crank arm ball (not shown) and the drive plate 24 comprises a drive plate ball (not shown).The arm 28 comprises an elongated rectangular member 29 (FIGS. 35) comprising a socket 32 and socket 34 which are over-molded thereon. As best illustrated in FIGS. 36, the first end 28a of mot

30、or drive link or flexible arm 28 comprises the socket 32 for mounting onto the drive plate ball (not shown) on drive plates 24, and second end 28b of motor drive link or flexible arm 28 comprises the socket 34 for receiving crank arm ball (not shown) on crank arm 30. As best illustrated in FIGS. 37,

31、 the first and second ends 28a and 28b comprise the sockets 32 and 34, respectively. Notice that socket 32 (FIG. 6) defines a socket area 40, respectively. It has been found that it is desirable to align the centerline CL (FIG. 5) with the axis of shafts 20a, 22a and 24a when the wipers 12 and 14 ar

32、e in the park position.As best illustrated in FIGS. 2A2C and 3, flexible arm 28 defines a length L1, which in the embodiment being described is in excess of 250 mm. During a fatigue condition, when the compressive load applied to the arm 28 exceeds a predetermined load (such as at least 30 percent of a maximum working load of flexible member 28 as defined below), the flexible arm 28 begins to flex or bend. This causes the flexible arm 28 to shorten to a length L2, illustrated in FIG. 2D, and this length L2 is shorter than length L1. As illustrated in the graphs shown in FIG