WINDSHIELD WIPER BALL JOINT

Abstract: The joint includes a ball stud (40) attached to one linkage member (34) and a stamped metal socket member (50) enclosing the ball stud (40) and resiliently urged within an aperture (46) of another linkage member (22).

Description: This invention relates to automotive windshield wiper transmission linkage and like apparatus and more particularly to a universal ball joint connection for linkage members of such apparatus. A universal ball joint connection for a gear-shift lever is disclosed in US-A-4,l0l,228, which has a two-part housing of synthetic plastics material, into which a ball may be easily inserted without there occurring any play between the ball and the housing. This invention is addressed most specifically to the well-known problems associated with provision of universal ball joint connections in such windshield wiper and like apparatus characterized by rugged use conditions which generally lead inevitably to some amount of wear in the joints after prolonged service life. As has been noted in US-A-3,299,72l and US-A-2,767,004, to the degree such wear occurs in the joint parts, it is desirable to automatically take up such wear to maintain a precise or tight connecting joint. The primary feature of this invention is that in accomplishing the noted objective of automatic wear take-up, there is provided an exceedingly economical construction employing simply a stamped sheet metal or otherwise economically formed socket member including a socket portion engaged over the usual ball stud of one linkage member and together therewith received in a tapered hole in a mated linkage member. The socket member is slotted and includes integral attachment portions operative to provide self-bias of the socket member axially within the hole taper to induce squeezing of the socket portion, automatically taking up ball joint wear to the degree such wear may occur. This principle feature and other features and advantages of the invention will be readily apparent from the following specification and from the accompanying drawings, in which: Figure l is a fragmentary, partially broken-away perspective view of an automotive vehicle windshield wiper mechanism including a transmission linkage ball joint according to this invention; Figure 2 is an enlarged view of a portion of Figure l taken generally along the plane indicated therein by the lines 2-2; Figure 3 is a further, enlarged, view of a portion of Figure 2 taken generally along the plane therein indicated by lines 3-3; Figure 4 is an enlarged perspective view of a component shown in Figure 3. Referring now particularly to Figure l of the drawing, this illustrates an automobile body including a windshield l0 and windshield wiper apparatus therefor including a widely spaced pair of wiper blades l2 and l4 adapted to oscillate in well-known manner over the windshield between a parked position, as shown, and some selected pattern limit position displaced clockwise, as seen in Figure l, from the parked position. The continuous cyclic or oscillatory co-ordinated motion of the wiper blades is conventionally accomplished by suitable transmission linkage driven by an electric motor drive unit, indicated generally at l6, which typically includes a direct current electric motor and speed reduction gear designed to provide low speed, high torque, continuous uni-directional rotation of an output crank arm member, shown at l8. It is, of course, usually desired that drive unit l6 be mounted to provide complete freedom of design both as to it and as to the transmission linkage, but crowding of the engine compartment places limits on that freedom and accordingly the unit l6 may have to be mounted in positions such as shown in Figure l, and certain parts of the linkage must accommodate substantial displacement in diverse planes during the operation thereof. The wiper transmission is designated generally as 20 and may include, in the particular style of wiper mechanism shown herein, a first link assembly 22 oriented generally transversely of the vehicle below windshield l0, a wiper shaft and housing assembly 24 for wiper blade l2, a second transversely oriented operating link 26, and finally a second shaft and housing assembly 28 for wiper blade l4. Link 22 includes an adjuster member 30 adjustably affixed to the end of a main link element and having in turn at its end a ball stud coupling 32 operatively connecting crank l8 with the link 22, and another such coupling connecting link 22 to assembly 24. Continuous rotation of the crank l8 in one direction will impart to the link 22 cyclic or back and forth motion transverse to the vehicle body as well as swinging motion in generally transverse planes thereof about its coupling to assembly 24. As seen best in Figure 2, wiper shaft and housing assembly 24 conventionally includes a connecting arm 34 having affixed intermediate its ends thereof for rotation therewith the lower end of a drive shaft 36 journalled within the housing 24. Oscillation imparted to the connecting arm by link 22 will provide the required oscillatory wiping pattern of wiper blade l2 over the windshield as well as transfer of co-ordinated similar oscillation to wiper blade l4 via the second operating link 26. Thus, shaft and housing assembly 28 includes in a form similar to assembly 24 just described another arm 38 affixed to a drive shaft in the housing assembly carrying arm l4. The two wiper shafts may be generally parallel, but minor misalignments between them may occur in vehicle assembly or field service adjustments. Thus, a further pair of ball stud couplings 32 operatively connect the adjacent ends of links 22 and 26 with connecting arm 34. Another such ball stud coupling 32 operatively connects the remote end of link 26 with the arm 38 of shaft and housing assembly 28. Accordingly, the various couplings 32 being constructed of ball stud and socket type couplings, relative rotation between the various connecting parts may occur in more than one plane during operation of the wiper mechanism as set forth. It is also preferred that the link members 22 and 26 be economically fabricated of stamped sheet metal having terminal end portions such as indicated in Figure 2 featuring a single flat stock thickness presenting minimum space consumption in the coupling areas. Referring to Figure 3, representative of the various ball stud couplings, there is provided in accordance with the invention a ball stud 40 having a shank 42 thereof secured within an aperture of link connecting arm 34 in conventional manner, and extended by a part-spherical coupling portion 44. First link member 22 is apertured as at 46 to receive coupling portion 44 as well as a ball socket portion of a socket member 50. Referring to Figure 4, socket member 50 is preferably of a stamped sheet metal configuration. It may be fabricated of commercially available material specifically adapted to bearing applications and characterized by a base constituent of spring-tempered steel provided with a bonded polytetrafluoroethylene (Teflon) coating or similar anti-friction material on surfaces of its socket portion. Said socket portion is designated as 52 and is integrally stamped or otherwise formed with substantially flat attachment flanges 56 separated by a slot 58. Each flange 56 is apertured as at 60 for purposes of riveting as will appear. Reverting to Figure 3, the tapered aperture 46 in link 22 is sized with a greatest diameter at or adjacent an under surface 62 of the link 22 and sufficiently larger than the largest diameter defined by the socket portion 52, when engaged over ball stud coupling portion 44, that said engaged parts may readily be inserted in the aperture to the position shown in Figure 3. Conversely, the largest diameter of the socket portion 52, when so inserted, is predeterminedly larger than the least diameter of the link aperture 46 at or adjacent an upper surface 64 of the link member. More specifically, with the ball coupling portion 44 and socket portion 52 installed within the aperture 46 with an axial thrust against the wall of the latter sufficient to wedgingly squeeze the slotted socket portion 52 against coupling portion 44 with a requisite radial force characteristic, or tightness, desired in the joint, nevertheless the least diameter of aperture 46 is still exceeded by the largest diameter of the socket by a planned margin. Such a margin determines an ultimate desired spacing, indicated at "a", between the flat flanges 56 when not yet riveted (represented in broken lines), and the undersurface 62 of link 22. It is noted that in such a condition slot 58 is far from squeezed closed. Rivets 66 placed in flange aperture 60 are then headed tightly at 68 over flanges 56 as attachment means which stress the large areas of the flanges flushly against link 22. Thus, resiliently deformed portions 70 of the socket member are created around the juncture of the socket portion 52 with said flanges 56, which partake of the resilience of the spring steel or like material of the socket member so as to provide constant bias within the body of such member urging socket portion 52 axially upwardly within the aperture 46. Thus, as any wear of material may occur in the socket and ball interfaces in link 22, the socket portion is biased upwardly against the gradually narrowing wall of aperture 46 and squeezed further and firmly over coupling portion 44, to preserve the desired tightness in the ball joint. A taper other than a pure conical taper in aperture 46 may be found desirable, and will be within the scope of the present invention. The spacing "b" (Figure 3) of rivet heads 68 from aperture 46 and the number thereof, along with the material thickness of socket member 50 and physical properties thereof, determine the extent and effectiveness of resiliently deformed portions 70. Wear take-up is thus assured by the resiliently deformed portions 70 urging the socket member 50 upwardly within the aperture 46.

Claims: 1. A universal joint for linkage apparatus including a pair of link members (22,34), said universal joint comprising, in one of said members (22), a hole (46) smoothly varying in diameter from a largest diameter adjacent one surface (62) of said one member (22) to a least diameter adjacent an opposite surface (64) thereof, a ball stud (40) on the other of said members (34) received in said hole (46), and a socket member (50) including a part-spherical socket portion (52) engaged in said hole (46) over said ball stud (40) and slotted so as to be squeezable to decreasing diameters upon movement thereof in a direction axially of said hole (46) towards said opposite surface (64), characterised in that said socket member (50) further includes integral resilient attachment portions (56) adapted to be placed in juxtaposition to said one surface (62), and attachment means (66,68) resiliently stressing said attachment portions (56) in secured relation to said one member (22) in a manner whereby said socket portion (52) is continually urged axially of said hole (46) towards said opposite surface (64). 2. A universal joint according to claim l, characterised in that said socket member (50) is of resilient material having formed therein said slotted socket portion (52) which, in a normal unstressed condition, has a greatest diameter which is intermediate said largest diameter and said least diameter of said tapered hole (46); said integral attachment portions are flange portions (56) which, while in a normal unstressed condition upon reception of said socket portion (52) in said hole (46) over said ball stud (40), are spaced from said one surface (62); and said attachment means (66,68) resiliently stress said flange portions (56) in secured relation to said one member (22) so that, upon wear occurring between said ball stud (40) and said socket portion (52), the latter is urged by said flange portions (56) axially of said hole (46) so as to be squeezed to decreasing diameters to take up such wear.

Inventors: HUESMAN, EDWARD HERMAN
Applicants: GENERAL MOTORS CORPORATION
Application year: 1986
Main classification: B60S1
IPC codes: B60S1, F16C11