Windshield Wiper Arm with Hemmed Distal End
A wiper arm (100) for a wiper assembly of an automotive vehicle, the wiper arm (100) being formed in a single piece from a metallic blank (100′) and having an inner end portion (100a) of generally U-shaped configuration in cross-section that is formed by drawing the blank (100′) in a progressive die, and an outer end portion (100b) that is formed with a C-shaped configuration in cross-section, by hemming. The outer end portion (100b) has a central portion (130) with edge portions (132) that are reversely folded to underlie the central portion (130), edges of the edge portions (132) being disposed in close proximity to one another. An end portion (100c) of the outer end portion (100b) of the wiper (100) is reversely folded to be spaced from and underlie a portion of the outer end portion (100b) thereabove, and the end portion (100c) is provided with an opening (126) by which a wiper blade may be attached to, or removed from, the wiper arm (100).
Latest CONCORD TOOL & MANUFACTURING, INC. Patents:
This application is a division of U.S. patent application Ser. No. 11/248,818 filed on Oct. 12, 2005.
FEDERALLY SPONSORED RESEARCH OR DEVELOPMENTNot Applicable
REFERENCE TO SEQUENCE LISTINGNot Applicable
BACKGROUND OF THE INVENTION1. Field of the Invention
This invention relates to a wiper arm for an automotive windshield wiper system. More particularly, this invention relates to a wiper arm of the aforesaid character of unitary construction with a narrow, thickened free or distal end of a double thickness that is formed by hemming.
2. Description of the Prior Art
Typical prior art windshield wiper arm assemblies 10 used on motor vehicles as shown in
The shape of the individual components of the retainer arm 14 is influenced by various demands and stresses. Specifically, they should be as torsionally rigid, deflection-resistant, and as narrow in the field of view as possible, so that the wiper blade can be guided without vibration and under control over the vehicle windshield yet present little hindrance to the field of view. The mounting head 12 transmits the drive moment from the drive axis A-A to the wiper blade, via the retainer arm 14 and the arm rod 16. It also forms part of the toggle joint 21, by way of which the mounting head 12 is braced with the retainer arm 14 by the tension spring 20 and pressed in the direction of the vehicle window. The greatest forces or moments arise in the mounting head 12, both parallel to the window and perpendicular to the window. Further, deformations in the lower region of the retainer arm 14 have an especially strong effect over the entire length and can cause uneven wiping speeds as a result of a spring effect. The mounting head 12 and the first portion of the retainer arm 14 must therefore be embodied as especially deflection-resistant and torsion-resistant.
In a wiping motion, the outward portion of the retainer arm 14 moves partly, and the wiper or arm rod 16 moves completely, through the field of view of the driver and as a result they must be made not only torsion and deflection resistant, but also especially narrow so that they impede as little of the driver's view as possible. Further, the retainer arm 14 should be shaped in such a way that it is not lifted away from the vehicle window by the air flow across the windshield.
To accommodate these various requirements, prior art windshield wiper arm assemblies 10 have a wide mounting head that may be made of zinc or aluminum die cast or sheet metal as well as a retainer arm 14 that is also made of sheet metal which is relatively wide in the region of the mounting head 12 that is, at the lower edge 22 of the field of view of the driver. Often, this portion of the retainer arm 14 is made with an inverted U-profile that is open towards the window as shown in
Generally, the wiper rod 16 is formed of a profile of constant thickness material solid flat stock, which is either crimped or riveted 30 as shown in
Further considerations to be made in the design of a complete windshield wiper system is the associated windshield washing system and considerations which need to be made with respect to the mounting of the spraying device on the hood or the windshield wiper arm assembly 10. The windshield washing system consists of a washing liquid reservoir, as well as a pump (not shown), by which washing liquid is sprayed onto the windshield to be cleaned by a spraying device. It is known that the spraying device may be stationarily arranged on the engine compartment hood. Further, the windshield cleaning system-spraying device may be fixed to the windshield wiper arm assembly 10. The advantage of fixing the spraying device to the windshield wiper arm assembly 10 is that the washing liquid is sprayed immediately in front of the wiper blade. In the prior art embodiment illustrated in
With reference to prior art
In order to solve high cost and high weight problems, some windshield wiper assemblies particularly teach the use of a retainer arm and wiper rod which can be made of a number of variable material layers which are folded upon one another in various regions until the material thickness required for the particular cross-section is obtained. A thin material is bent over multiple times by approximately 180° in multiple steps in order to brace each layer. The advantage, of course, is from a relatively thin sheet of metal, different material thickness can be obtained in different regions and this thickness can be adapted exactly to different stresses that arise. Unfortunately, small material stress cracks, virtually invisible to the eye, can result from these multiple bending operations and as a result, such minute cracks, if they occur on the outer surfaces, can cause excessive noise by wind passing thereover when exposed to a high wind stream. Further, obviously, the multiple layers of metal in order to accomplish the appropriate size requirements, may also result in higher material costs as well as higher weights due to the multiple layers which are necessary in order to provide the appropriate structural rigidity for the torsion and deflection forces that are known in selective areas of the windshield wiper assembly. Generally, to enable the use of multiple layer assemblies, a thinner material is used in order to make the multiple folds which are necessary to acquire the particular cross-section needed to resist the known deflection and torsion moments.
U.S. Pat. No. 6,505,377 B1 (Merkel et al.) discloses a wiper arm or wiper rod, element 18, for a windshield wiper assembly, the wiper rod being formed from multiple layers of a single thickness component sheet of metal (column 2, lines 30-39). The free or distal end of a one-piece wiper rod according to this reference is formed with four thicknesses of metal by a stamping operation,
The '377 reference also discloses an alternative embodiment, the embodiment of
U.S. Pat. No. 6,732,401 B1 (Rapp), which shows an assignment to the same assignee as the '377 patent, shows, in
The aforesaid and other problems associated with prior art wiper arm constructions are avoided by a wiper arm constructed according to the present invention that is fabricated from a single thickness blank of a suitable material. An inner portion of the wiper arm, which is generally U-shaped in cross-section, is formed by a drawing operation in a progressive die. An outer portion of the wiper arm is formed by hemming into a double thickness, a generally C-shaped configuration with no spacing between a single thickness layer of material of the arm and an in-turned pair of material edges that extend from opposite sides of the single thickness layer. Such a configuration has sufficient resistance to deflection and torsional moments under aerodynamic loads to maintain a wiper blade attached to the distal end of the wiper arm in engagement with an adjacent windshield, it is sufficiently narrow at the distal end to avoid undue visual interference to an operator of an associated vehicle, and it is sufficiently thin in a transverse direction to be aesthetically clean and visually undistracting. The wiper arm of the present invention is also lower in weight than known prior art wiper arm constructions, it is relatively inexpensive to produce due to it's single piece construction, and it incorporates a more accurately positioned hole in a reverse turned hook end for accurate attachment of a wiper blade to the wiper arm itself without the need of a resizing operation to fit the hook like end between the cheeks of the support bracket it engages. Further, the mounting bracket for attachment of the spray nozzle is formed from the extended portion of the U-shaped legs of the retainer arm so that no additional parts or assembly operations are required to attach this mounting bracket because additional material is provided in the original blank that is carried through the progressive die.
Accordingly, it is an object of the present invention to provide an improved, economical, light weight wiper arm for a windshield wiper assembly that is fabricated from a single thickness blank of a suitable material, that has a free or distal end that is narrow in the line of sight of an operator of an associated vehicle, that is both thin in a transverse direction and is provided with sufficient resistance to deflection and torsion moments under aerodynamic load, and can be made free of cracks and other surface irregularities that would otherwise be noisy when the associated vehicle is driven at highway speeds.
It is a further object of the present invention to fabricate an improved wiper arm for a windshield wiper assembly that is economical to manufacture by hemming the wiper rod portion of the retainer arm and provide additional material in the single piece blank to enable fabrication of the mounting bracket for the attachment of the spray nozzle out of the single piece blank.
For a further understanding of the present invention and the objects thereof, attention is directed to the drawing and the following brief description thereof, to the detailed description of the invention and to the appended claims.
The one-piece wiper arm as illustrated in
One of the legs of the U-channel section, shown in
As is shown in
An outermost end portion 100c of the outer end portion 100b of the one-piece wiper arm 100 is reversely folded by a cam form operation to form the hook end 120 which is spaced from and extends parallel to a portion of the outer end portion 100b that is thereabove. This outermost end portion 100c of the outer end portion 100b is the portion of the one-piece wiper arm 100 that is provided with the opening 126, and the spacing between the outermost end portion 100c and the portion of the outer end portion 100b thereabove provides a clearance for the proper attachment of a wiper blade to the one-piece wiper arm 100 and for the easy removal of the wiper blade when it is required to replace the wiper blade. The progressive die operation final sizes the width of the hook end 120 in order to fit the hook end 120 between the cheeks of the support bracket of the wiper blade.
Although the best mode contemplated by the inventor for carrying out the present invention as of the filing date hereof has been shown and described herein, it will be appreciated by those skilled in the art that suitable modifications, variations, and equivalents be made without departing from the scope of the invention, such scope being limited solely by the terms of the following claims and the legal equivalents thereof.
Claims
1-4. (canceled)
5. A method of making a unitary wiper arm, said method comprising the steps of:
- providing a single thickness blank adapted to be carried through a progressive die;
- forming an inner portion of said unitary wiper arm in the form of a generally upward formed cross-section by a drawing operation in said progressive die, said upward formed cross-section having a bight portion with extending opposed legs;
- forming an outer portion of said unitary wiper arm into a generally double thickness configuration by in-turning said material edges that extend from opposing sides of said single thickness layer of material by a hemming operation in said progressive die;
- removing said formed wiper arm from said single thickness blank carried through said progressive die.
6. The method as claimed in claim 5 further comprising the step of:
- forming axially aligned openings in said extending opposed legs to permit mounting of said unitary wiper arm to a mounting head.
7. The method as claimed in claim 5 further comprising the step of:
- providing one of said extending opposed legs with a material extension; and
- cam forming said material extension from said one of said opposed legs into a support bracket located between said extending opposed legs.
8. The method as claimed in claim 7 further comprising the step of:
- attaching a spray nozzle to said support bracket located between said extending opposed legs.
9. The method as claimed in claim 5 wherein said forming an outer portion of said unitary wiper arm further comprises the step of:
- forming said in-turned material edge portions over a central material layer with no appreciable spacing between said in-turned material edge portions and said central material later portion to form said double thickness configuration, said free edges of said in-turned material edge portions touching or in very close proximity with one another.
10. The method as claimed in claim 5 further comprising the step of:
- cam forming the outermost end portion of the unitary wiper arm into a reversely folded hook portion which is spaced from and extends parallel to a portion of the hemmed outer portion of said unitary wiper arm, to provide a spacing for the proper attachment of a wiper blade to the unitary wiper arm when it is required to remove said wiper blade.
11. The method as claimed in claim 6 further comprising the step of:
- final forming the width of said reversely folded hook portion so as to enable easy fitting of said hook portion between the cheeks of the support bracket attached to said wiper blade.
Type: Application
Filed: Jul 2, 2009
Publication Date: Jan 7, 2010
Applicant: CONCORD TOOL & MANUFACTURING, INC. (Mt. Clemens, MI)
Inventor: Jeff Vandine (Macomb, MI)
Application Number: 12/496,977
International Classification: B21C 23/00 (20060101);