Unitary cowl and wiper arm assembly

Abstract: The assembly includes a blow-moulded plastics shell structure (18,20) and two wiper arms (58) of the integral type. At two locations, the shell (18,20) is reformed so as to create an area (38) of increased stiffness that includes a pair of spaced, overhanging interior flanges (40,42). This allows a journal portion (64) of a respective wiper arm (58) to pass through the shell (18,20) and be pivoted thereto between the spaced interior flanges (40,42). Thereafter, the arm (58) is rigidly and securely supported. The leakproof interior portions (46,48) of the shell (18,20) may also be used for a fluid reservoir.

Description: This invention relates to a cowl and wiper arm assembly for a motor vehicle as specified in the preamble of claim 1, for example as disclosed in US-A-3,264,670. Background of the Invention Automotive vehicle bodies usually have a gap between a back wall of an engine compartment and a lower edge of the windshield. This gap is bridged by a part that is referred to variously as a cowl, cowl panel, beauty panel or leaf screen. The cowl is secured along its lower edge to the body wall and along its upper edge to, or near, the lower edge of the windshield, and may be partially covered itself by the rear edge of the hood, especially in designs with hidden windshield wipers. Given its proximity to the windshield, the cowl provides a convenient foundation for the windshield wipers. Most often, the cowl is a single sheet structure to which is fixed a cylindrical housing that provides a sleeve bearing for a pivot shaft of a wiper arm. With such an arrangement, the pivot shaft must be passed through the bearing housing first, and the wiper arm completed afterwards by attaching a crank arm to a lower end of the pivot shaft and a blade support to an upper end of the pivot shaft. Examples of such built-up wiper arms and their pivot arrangements may be seen in US-A-4,509,878 (Bryson et al) and in US-A-4,028,950 (Osterday). It is also known to use a wiper arm which, rather than being built-up in stages, is integral or single piece. An integral arm has a crank arm on one end and a blade mount on the other end, offset from one another by an intermediate cylindrical journal that is generally perpendicular to both. A one-piece arm cannot be passed through a sleeve or bearing housing. Instead, a stationary shaft is used that is fixed to a body support, and the journal arm is slipped over the free end of the shaft to pivot on the fixed shaft. An example may be seen in US-A- 3,604,048 (Mainka). In all three of the above examples, the part that provides the bearing for the wiper arm, whether it be a cylindrical housing or a shaft fixed to the cowl, can act like a lever, tending to twist and bend the cowl when the arm is disturbed. Forces tending to disturb the arm may come from several sources, but the force of the drive linkage acting on the crank arm is generally the greatest. It may be difficult for a single sheet of material to resist these bending moments, especially when the pivot bearing has a significant length. This necessitates either that the cowl be made of heavy gauge material, or that it be reinforced, as in US-A-3,604,048. US-A-3,264,670 (Barenyi et al) shows, in one embodiment, a foundation for a wiper arm that consists of more than a single sheet. Specifically, as seen in Figure 5 of US-A-3,264,670, upper and lower metal panels are seamed together along their outer edges to create a box that is hinged along its lower edge only to the vehicle body, without being secured to the windshield at all. The wiper arm is the built-up type, with a cylindrical bearing housing and a pivot shaft journal through it. The bearing housing is joined to the two spaced panels of the box in basically the same way that it would be joined to a single panel. That is, the bearing housing is passed through the panels, although two aligned holes are needed in this instance, as there are two panels. It would be just as difficult, more so in fact, to pass an integral-type wiper arm through a pair of aligned holes, as opposed to passing it through a single hole in a single panel. It could be done if the holes were greatly oversized, but that would remove most of the panel material around the potential pivot point. US-A-3,264,670 is not directed to improving the mounting of the wiper arm to the cowl per se, but to mounting several other components, including the motor and drive linkage, to the cowl. Summary of the Invention A cowl and wiper arm assembly according to the present invention is characterised by the features specified in the characterising portion of claim 1. The invention provides a unitary cowl and wiper arm assembly that provides the structural stiffness of a shell, having two layers or panels flanged together along their peripheral edges. However, the shell is specially configured to create areas of increased stiffness that not only allow a wiper arm of the integral type to be easily passed through the shell, but also allow it to be pivoted to the shell with increased rigidity. In addition, in the preferred embodiment of the invention disclosed, the shell is made as a plastics blow-moulded structure that provides a leakproof washer fluid reservoir with no additional structure. The main body of the assembly is a shell with upper and lower panels seamed together along their peripheral edges. At specific locations, the panels are crimped together in opposite directions, thereby creating an area of increased stiffness bordered by upper and lower shell portions. Specifically, the upper panel is deformed locally down against the lower panel at a location substantially midway between the peripheral flanges, at an acute angle to the desired axis of rotation of the wiper arm. Concurrently, at a closely adjacent location, the lower panel is crimped up against the upper panel and in opposite and parallel direction. This selective reforming of the shell creates a double-thickness wall with a generally Z-shaped cross-section, including upper and lower overlapping interior flanges spaced apart by a diagonally-extending wall. The upper and lower flanges, in turn, are bordered by structurally complete upper and lower shell portions. In the embodiment disclosed, the upper and lower panels are plastics skins, so the interior of the shell is leakproof. Once the shell has been reformed as described, a sufficient portion of the diagonally-extending wall is cut away to allow the arm to pass therethrough, but the fluid tightness of the interior is not jeopardized. The cylindrical journal of the arm is pivoted between the overlapping flanges. This locates the blade support of the arm above the lower shell portion, where it will extend over the windshield, and locates the drive member below the upper shell portion, where it is protected. The shell and arm, together with any other components secured to the shell, form a unit that may be secured in one step to the vehicle. In operation, the arm will be very rigidly confined between the overlapping interior flanges. Disturbing forces acting on the arm will be initially resisted by the high stiffness of the double-thickness flanges and the diagonal wall. Since the area of increased stiffness is integral with the rest of the shell and located generally centrally in the shell, substantially the entire shell will also see and resist any deformation in that area. The blow-moulded seams are strong enough to resist parting, so windshield washer fluid may be stored in the hollow interior of the shell. A washer pump and nozzle may also be secured to the shell, and the ducting needed to connect the pump to the nozzle may be moulded integrally into the shell, eliminating more standard components and fittings. It is, therefore, an object of the invention to provide a unitary cowl and wiper arm assembly that provides the structural stiffness of a shell, but which allows an integral-type wiper arm to be easily passed through and pivoted thereto. It is another object of the invention to locally reform the shell to create an area through which the integral wiper arm may be easily passed and which has an increased stiffness so that the arm can be securely pivoted at that location to the shell. It is yet another object of the invention to locally reform the shell by crimping the lower panel up against the upper panel and concurrently crimping the upper panel down against the lower panel at an adjacent location and in a direction tilted relative to the desired axis of the wiper arm pivot, thereby creating upper and lower overlapping interior flanges between which the journal of the wiper arm may be pivoted. It is still another object of the invention to provide a shell and wiper arm unit in which the shell is a blow-moulded plastics structure to which the arm may be securely pivoted without disturbing the fluid-tight interior of the shell, so that the assembly may also provide fluid storage and handling capacity. Description of the Preferred Embodiment These and other objects and features of the invention will appear from the following written description, and from the accompanying drawings, in which: Figure 1 is a perspective view of a shell of a unitary cowl and wiper arm assembly according to the invention, before the wiper arms are added, showing the position of a windshield and bulkhead wall of a vehicle body in dotted lines; Figures 2 to 4 show steps in the process of forming the shell of Figure 1; Figure 5 shows a cross-section of the shell of Figure 1, taken through one area of increased stiffness; Figure 6 shows various parts of the area of increased stiffness cut-out to allow the wiper arm to be pivoted thereto; Figure 7 is a sectional view taken along the line 7-7 of Figure 6; Figure 8 is a view of the integral wiper arm before attachment to the shell; Figure 9 is a view of the wiper arm after attachment and after installation of the shell; Figure 10 is a sectional view taken along the line 10-10 of Figure 9; Figure 11 is a view like Figure 10 but showing the reaction to disturbing forces on the arm, Figure 12 is a plan view of the shell; Figure 13 is a cross sectional view taken along the line 13-13 of Figure 12; and Figure 14 is a cross sectional view taken along the line 14-14 of Figure 12. Referring first to Figures 1 and 9, a portion of a vehicle body 10 and a windshield 12 are illustrated. Vehicle body 10 typically includes a bulkhead engine compartment wall 14 that runs generally parallel to a lower edge of the windshield 12, creating a gap that must be covered. The assembly of the invention, a preferred embodiment of which is indicated generally at 16, is a unit sized and configured so as to cover the gap, and is installed by securing it to the windshield 12 and the wall 14. The basic structure of assembly 16 may be clearly understood by reference to its process of manufacture, described next. Referring next to Figure 2, the main structure or foundation of assembly 16 is manufactured from a blank known as a "parison", indicated generally at 17. Parison 17 is a workpiece of standard length and size formed from an extruded plastics tube of high density polyethylene, polypropylene or other suitable material. When parison 17 is partially collapsed to the general shape shown, it may be thought of as being a rough shell with upper and lower panels 18 and 20 respectively. The panels 18 and 20 are generally parallel and symmetrical, so parison 17 may be regarded as having a generally central plane to either side of which are disposed the panels 18 and 20. Parison 17 is placed in between a pair of upper and lower dies or moulds, indicated at 22 and 24 generally. Upper mould 22 has an inner surface that includes a projection 26 located about midway between its outer edges, whilst the surface of lower mould 24 has a closely adjacent projection 28 of similar shape and generally parallel orientation. In the embodiment disclosed, there would be two sets of die projections like 26 and 28. Whilst the projections 26 and 28 of each set are basically parallel to one another, they are not exactly perpendicular to the general plane of the parison described above. Stated differently, since the desired axis of rotation of the wiper arm, described below, will be generally normal to that plane, the projections 26 and 28 may be considered to have an acute angle or tilt relative to that axis. Referring next to Figures 2 to 4, as the dies 22 and 24 are closed together, the projections 26 and 28 of each set will shear closely past one another in opposite but parallel directions, like the blades of a pair of scissors, or like a pair of upper and lower front teeth. After the dies 22 and 24 are closed, the facing surfaces of the projections 26 and 28 will be spaced from one another by approximately the combined wall thicknesses of the panels 18 and 20. Comparing Figures 4 and 5, it may be seen that the general effect on parison 17 is to push or crimp the lower panel 20 upwardly towards the upper panel 18 at a location approximately midway between the edges of the dies 22 and 24, whilst concurrently the upper panel 18 is pushed or crimped downwardly toward the lower panel 20 at a closely adjacent location. Simultaneously, the outer edges of the panels 18 and 20 are seamed together by edges 30 of the dies 22 and 24. After the dies 22 and 24 are closed, compressed air is blown between the panels 18 and 20 to conform them to the entire inner surfaces of the dies 22 and 24. Referring next to Figures 5 and 12, the result of the above process is a finished plastics shell, designated generally at 32. Shell 32, when cool, is structurally complete and stiff, with first and second peripheral flanges 34 and 36 that may be fastened or glued to the desired part of the vehicle. Although the upper and lower surfaces or skins of finished shell 32 have many undulations and features moulded into them, they are still basically the upper and lower parison panels 18 and 20, and shell 32 may also be considered to have a generally horizontal central plane. Most significant to the invention here are the areas where shell 32 has been reformed by the projections 26 and 28, which are circled and indicated generally at 38. These areas, of which there are two, are locally more stiff than the rest of shell 32, as will be described in more detail below. Areas 38, although integral with the whole shell 32, may be thought of as separate substructures, and described in several possible ways. Looking at just the surfaces of shell 32, a logical way of describing each area 38 would be as adjacent concavities in the upper and lower surfaces. The concavities are important in that they provide sufficient clearance to allow a wiper arm, described below, to be oscillated. However, it is more useful to describe the tangible part of area 38, rather than the voids, which is best done in the sectional views. Referring next to Figures 5, 6, and 7, area 38, when it is sectioned through, may be described as a a double thickness wall with a Z-shaped cross-section. More specifically, the Z-shape is comprised of spaced upper and lower interior flanges 40 and 42 which lie generally parallel to the plane of shell 32, and which are joined by a diagonally-extending central wall 44. Because of the relative orientation and location of the die projections 26 and 28 described above, the interior flanges 40 and 42 overlap or overhang one another, and are kept rigidly spaced by the wall 44, which is inclined relative to the central plane of shell 32. The overlapping relation of the flanges 40 and 42 serves an important purpose described below. Whilst the part of shell 32 bordering each of the interior flanges 40 and 42 is integral with the entire shell 32, it, too, may be described as a separate substructure, specifically as upper and lower shell portions 48 and 46 respectively. The upper and lower shell portions 48 and 46 are likewise spaced from one another, and are each structurally complete and stiff, that is, they are bounded by the peripheral flanges 34 and 36 and by the interior flanges 42 and 40 respectively. As best seen in Figures 6 and 7, the desired wiper arm pivot axis 50, which is generally normal to the plane of shell 32, is defined by cutting aligned circular holes 52 and 54 through the interior flanges 40 and 42. Central wall 44, which has an acute angle relative to axis 50, is cut-out at 56 to provide arm clearance. An important property of shell 32 is that, since the panels 18 and 20 are plastics and uninterrupted, and since all of the various flanges 34, 36 and 40, 42 have fluid-tight seams, the entire inner volume of the shell is fluid-tight, which serves a purpose described below. Referring next to Figures 8 and 9, the other basic part of the assembly 16 is a wiper arm, designated generally at 58. Arm 58 is an integral, one-piece type, with a blade mount 60 and a generally parallel drive member 62 offset from one another across a generally perpendicular bearing journal 64. Whilst an integral arm like 58 could not be passed through a pair of aligned round holes the size of 52 and 54, it can be passed through shell 32 and pivoted thereto at the area 38. In particular, the orientation and separation of the upper and lower interior flanges 40 and 42, and the size of the cut-out 56 through wall 44, allow the arm blade mount 60 to be inserted through cut-out 56 until the journal 64 is located between the interior flanges 40 and 42, aligned with axis 50. Arm journal 64 is sandwiched between a flat, upper thrust washer 66 that sits against the undersurface of upper flange 40 and a lower, stepped thrust washer 68 that fits through lower flange hole 54. A layer of low-friction, partially compressible material 70 may be placed between lower washer 68 and the lower end of journal 64 to take up tolerance variations. Then, a bolt 72 is pushed through journal 64 and a nut and washer assembly 74 is threaded to the lower end of bolt 72. Arm 58 is thus securely and squarely pivoted to the shell 32 with the blade mount 60 above the upper shell portion 48 and the drive member 62 located below the lower shell portion 46. Two arms 58 are pivoted to shell 32 in this fashion, one at each area 38. Then, the entire assembly 16 is installed to the vehicle body 10 by cementing the first peripheral flange 34 to the windshield 12 and fastening the second peripheral flange 36 to the bulkhead 14. So, the particular configuration of area 38 provides two important advantages in the manufacture and installation of assembly 16, allowing the arm 60 to pass easily through the shell 32, and also providing a convenient pivot point between the overlapping interior flanges 40 and 42. Since the various holes 52, 54 and 56 do not disrupt the fluid-tight interior of shell 32, it can, with the addition of a suitable cap, be filled with windshield washer fluid, as shown. Washer fluid bottles are relatively large in volume, and occupy a significant portion of the under hood space, so it is a great advantage to replace such items with the otherwise empty volume of the shell 32. Given its large area, shell 32 need not be especially thick to supply a large volume usable to hold windshield washer fluid. Referring next to Figures 10 and 11, it may be seen how the area 38, besides allowing arm 58 to be easily pivoted to the shell 32, also improves the operation of arm 58. Arm 58 is subject to fairly severe disturbing forces, especially from the drive linkage, not shown, acting on the drive member 62, which tends to tip the journal 64. In a conventionally mounted arm, the arm drive member 62 would be located below the cowl, some times well below, creating a relatively large leverage that would act strongly to deform the cowl, be it a single or double panel structure. Here, by virtue of the way the arm 58 is passed through and pivoted to the shell 32 at the area 38, the drive member 62 and journal 64 are effectively located inside the shell 32. That is, journal 64 is located axially between the interior flanges 40 and 42, and laterally between the upper and lower shell portions 48 and 46. This location significantly reduces the leverage with which the journal 64 can act on any part of the shell 32. Furthermore, the entire configuration of the area 38 co-operates to strongly resist any deformation that does occur. The area 38, by virtue of being crimped down and up, is significantly stiffened relative to the rest of the shell 32, like a corrugation in a single panel. Furthermore, the interior flanges 40 and 42 to which the journal 64 is directly pivoted, and wall 44, are stiff by virtue of being double thickness. The wall 44, even after being cut-out, strongly resists movement of the flanges 40 and 42 away from or towards one another. In addition, by virtue of the fact that area 38 is integral with and located generally centrally within the shell 32, any forces that the flanges 40 and 42 experience are distributed effectively and efficiently throughout the rest of the shell 32. Specifically, any deformation of the area 38 is resisted by the bordering upper and lower shell portions 48 and 46, and, from there, the forces are distributed throughout the upper and lower panels 18 and 20. The degree of deformation shown in Figure 11 would, in fact, not likely occur because of the high strength and rigidity of shell 32 and the area 38. The seams in the area 38 are strong enough to remain intact, so the fluid-tightness of the interior is not affected. Referring next to Figures 12, 13 and 14, an additional advantage of assembly 16 that is achieved with little or no additional structure may be seen. When shell 32 is moulded, its central area running between the two areas 38 is crimped down to create a flat shelf 76 that is slotted or louvered to admit air for an air conditioning and ventilation system of the vehicle. Blow-moulded integrally into shelf 76 is a washer fluid passage 78. The lower end of passage 78 may be connected to the outlet of a pump, the general location of which is shown at 80. Pump 80 may also be secured to the shell 32, and draws fluid from the interior thereof. The upper end of passage 78 has a nozzle 82 mounted through it to spray the windshield 12 with windshield washer fluid. Incorporating the passage 78 into the shell 32 gives an even more unitary construction and reduction of separate parts, by eliminating the conventional washer hose. Variations of the preferred embodiment may be made within the concept of the invention. The shell 32 need not incorporate the fluid reservoir in its interior and the integrally moulded passage 78, but could be used as a structural foundation only for mounting the wiper arms 58. On the other hand, if it were desired to use the shell 32 as a reservoir, but to mount a more conventional type of wiper arm to the shell 32, that could be done as well, so long as the arm was pivoted to and through the shell 32 in such a way as to keep the interior thereof fluid-tight. The area of increased stiffness 38 provides a particularly advantageous way of mounting the wiper arm 58 to shell 32, however, since the flanges 40 and 42 and wall 44 do not disturb the fluid-tight nature of the interior of shell 32. Area 38 need not be exactly midway between the peripheral flanges 34 and 36, but its generally central location allows it to efficiently transmit the wiper arm torque forces that it experiences throughout the shell 32. Therefore, it will be understood that the invention is not intended to be limited to just the embodiment disclosed.

Claims: A cowl and wiper arm assembly (16) for a vehicle having a windshield (12) and a vehicle body (10), a portion (14) of which is spaced from said windshield (12), said assembly comprising a wiper arm (58) having a drive member (62) at one end and a blade support (60) at the other end offset from one another, and a cowl structure (17) in which a bearing journal (64) of the wiper arm (58) is pivotally mounted, characterised in that the cowl structure comprises a shell having upper and lower panels (18,20) seamed together at their outer edges to form a structurally complete member with first and second peripheral flanges (34,36) adapted to be secured to said windshield (12) and vehicle body portion (14) respectively, said lower panel (20) being crimped up against said upper panel (18) at a first location (40) substantially midway between said peripheral flanges (34,36) and said upper panel (18) being crimped down in the opposite direction against said lower panel (20) at a second location (42) adjacent said first location (40) so as to create a localized area (38) of increased stiffness integral with said shell and bounded by a structurally complete lower shell portion (46) offset sufficiently from a structurally complete upper shell portion (48) to allow said wiper arm (58) to pass between said upper and lower shell portions (48,46), said wiper arm (58) being passed through said shell at said area (38) of increased stiffness and being pivotally mounted to said shell at said area (38) with said blade support (60) located above said upper shell portion (48) and with said drive member (62) located below said lower shell portion (46) to form an assembly that can be installed to said vehicle as a unit, after which any torque forces acting on said wiper arm bearing journal (64) during subsequent operation of said wiper arm (58) will be resisted by said area (38) of increased stiffness and substantially the entire shell. A cowl and wiper arm assembly according to claim 1, characterised in that said shell is a blow-moulded plastics shell (32) having said upper and lower panels (18,20) seamed together at their outer edges to form a structurally complete member (32) with fluid-tight first and second peripheral flanges (34,36), so that fluid may be contained between said panels (18,20), so that said wiper arm (58) and shell (32) form an assembly that can be installed to said vehicle (10) as a unit within which fluids may be held. A cowl and wiper arm assembly according to claim 2, characterised in that the blow-moulded plastics shell (32) includes a slotted flat shelf (76) which contains therein an integral blow-moulded washer fluid passage (78), a lower end of which is connected to a pump (80) arranged to withdraw fluid contained within said shell (32) and an upper end of which has a washer nozzle (82) mounted therein.

Inventors: BUCHANAN HARRY C JR, MCCLAIN MICHAEL J, REED GLENN R, BUCHANAN, HARRY C., JR., MCCLAIN, MICHAEL J., REED, GLENN R.
Applicants: GEN MOTORS CORP, GENERAL MOTORS CORPORATION
Application year: 1989
Main classification: B60S1
IPC codes: B60S1, B62D29, B62D25