Patent Application
20080109981
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This invention is a mirror wiping device for highway vehicles.
One problem with driving highway vehicles—in particular trucks and buses—is the difficulty of keeping rearview mirrors clean in inclement weather. Automobiles generally have interior rearview mirrors and most now have means to keep the rear windshield clean, so they are not as critically affected as trucks and buses, which rely almost entirely on exterior mounted mirrors for rear vision. Under normal conditions they function adequately, but during rain or snow they can quickly become so covered with moisture and/or road debris as to be useless. Heated mirrors are widely available but they do not provide adequate protection in many weather conditions. The origin of the present invention came when the inventor had to drive a truck on a long trip on a day when the weather was such that after less than a mile of travel the mirrors became completely obscured and thus were useless.
This is not a new problem, obviously, and many attempts have been made to solve it. The inventor has found at least 33 prior patents on wiping devices for vehicle mirrors, and yet not one has found commercial success. In order to be successful, a wiping device must meet certain criteria. First, it must be simple, rugged, and reliable. Second, it must be as unobtrusive to the driver as possible. Third, it must be able to survive and function in all types of weather; including freezing rain, which will liberally coat everything it hits with a layer of ice. Fourth, it must be as economical as possible to manufacture and install, as trucking is an extremely competitive business and most truck buyers will not be willing to pay large sums for items that are not absolutely essential. Finally, it must be packaged in an attractive and unobtrusive manner so as to not be aesthetically displeasing.
Several patents have been granted for devices that have significant space on one or both sides of the mirror occupied by mechanism; these would be objectionable because they present a significant blockage to the driver's vision; the mirror itself is blockage enough, and most drivers would regard anything that extends beyond the sides of the mirror to be unacceptable. Examples of this are U.S. Pat. No. 6,453,504 to Burkard et al, Sep. 24, 2002, U.S. Pat. No. 6,654,982 to Cowan, Dec. 2, 2003, and U.S. Pat. No. 6,772,469 to Pidgeon, Aug. 10, 2004.
The simplest way of accomplishing the task would be to have a conventional wiper arm with a parallelogram linkage and a conventional wiper motor behind the mirror; variations of this have been patented several times, notably U.S. Pat. No. 3,855,661 to Prince, Dec. 24, 1974, U.S. Pat. No. 4,763,381 to Williams, Aug. 16, 1988, and U.S. Pat. No. 5,760,956 to Maccan, Jun. 2, 1998. A related attempt was to make the shape of the mirror conform to the wiper path as in patent 2,944,277 to Ochello, Jul. 12, 1960. In the opinion of the inventor these failed primarily because they were too intrusive on the driver's vision as the wiper arm would always be over an important part of the mirror, or, in the case of 2,944,277 to Ochello et al, Jul. 12, 1960, it was aesthetically unacceptable as well as having the motor partially obscuring the driver's vision.
There are several patents for wipers that are horizontal across the surface of the mirror and travel vertically up and down; examples are U.S. Pat. No. 4,457,597 to DeGideo, Jul. 3, 1984, U.S. Pat. No. 4,873,740 to Vahrenwald et al, Oct. 17, 1989, and U.S. Pat. No. 6,546,590 to Waters, Apr. 15, 2003. This inventor considers that approach to be unacceptable because it would tend to collect rain, snow, and dirt on top of the wiper blade and would therefore be much less likely to clean the mirror in a single pass.
By elimination this leaves a vertical blade traveling across the face of the mirror guided on the top and/or bottom as the only acceptable option. There are also quite a number of patents using this approach, such as U.S. Pat. No. 6,691,365 to Graf, Feb. 17, 2004 which utilizes a oscillating drum and two cables driving a wiper blade on tracks. The biggest problem with this design is that the cables are driven strictly by friction on the drum, and if they slip the blade will become misaligned and almost certainly jammed. Another approach is demonstrated by U.S. Pat. No. 5,353,466 to Smith et al, Oct. 11, 1994. This approach relies on microswitches to reverse the blade, which this inventor considers undesirable, as it requires more wires and a control module. Also, this leaves the microswitches potentially exposed to water and salt, reducing the reliability and increasing the cost if the microswitches are sufficiently weatherproof. Another problem is the fact that wire rope is subject to much more fatigue when going over extremely small pulleys, and this design relies on very small pulleys to achieve the desired package. This objection also applies to U.S. Pat. No. 5,363,236 to Han, Nov. 8, 1994. A different approach is demonstrated by U.S. Pat. No. 4,339,169 to Addison, Jr., Jul. 13, 1982. This relies on a wiper on a bracket looping around the mirror and driven by a bellcrank, and guided by recirculating ball bushings riding on rods. This would be very difficult to keep clean enough to continue working in the environment of a heavy duty highway vehicle. The same applies to U.S. Pat. No. 3,526,920 to Boyanich, Sep. 8, 1970. There are several other approaches that have been tried, but as mentioned earlier, none has found commercial acceptance.
Accordingly, the present invention incorporates the following advantages:
a) It is operated by an existing gearmotor already in mass production and of a proven, reliable design, providing the necessary oscillatory motion as well as a built-in parking function requiring only two wires for power if the chassis is used for return; or three wires if a separate ground is desired.
b) It is driven by a single stainless steel wire rope over pulleys large enough to minimize fatigue and secured to both the wiper and the driving pulley to eliminate the possibility of slippage.
c) The wiper is guided on the upper end by a guide with an anti-friction liner riding on an inverted L-shaped track provided with a protective cover so as to minimize its susceptibility to ice and snow blocking its travel. It is similarly guided on the lower end by a guide and vertical blade track located under the housing for protection.
d) The main housing can be symmetrical, allowing the same components to be used to provide either left-side or right-side parking by inverting the main housing and related components. Alternatively, the housing can be asymmetrical and the cable can be wound around the drive sheave in the opposite direction to park on the opposite side which still would use the same components for left hand and right hand versions.
In accordance with the present invention a mirror and wiping device for a highway vehicle comprising a frame, an oscillating motor, a driving pulley, eight guide pulleys, a drive cable, a spring to maintain cable tension, a mirror, a mirror inserts, a wiper arm with a replaceable squeegee blade, and a protective and decorative cover.
Note: where multiple items are used, they are designated with letters; i.e. 5A, 5B, etc.
Note also that fasteners are not called out unless they bear directly on the function and utility of the invention.
The drawings show the invention in the preferred embodiment for heavy duty trucks and buses.
This invention would typically be mounted in the same place as a normal mirror on a truck or bus. The invention would utilize pre-existing technology washer hose, pump and nozzle to provide a washing function. The invention can also be provided with remote angle adjusting means that also is pre-existing technology. The invention would be started by the driver pushing a button which would activate the washer motor and the wiper at the same time; the washer would would activate the washer motor and the wiper at the same time; the washer would continue for as long as the button is pressed and the wiper would have an electronic timer to continue for a predetermined time after the washer stops, and would then return to its park position. It could also be provided with a switch and a delay timer, so that it would wipe without washing at adjustable intervals exactly as the interval wipers on a modern automobile are operated. Again, this is existing technology and so is not included as part of this invention.
Another embodiment would be to power the wiper by an air motor instead of electric for use on heavy duty trucks, since many times air powered accessories are preferred on heavy duty trucks because of lower cost and/or greater reliability due to the corrosion that frequently occurs to electrical connections in the harsh environment in which trucks operate. As air operated wiper motors are readily available and oscillate exactly as do electric ones, this is a simple substitution. This inventor believes that electric motors are preferable, as they offer interval and time to shutdown features unavailable in air motors. Alternatively, the wiper could be powered by a linear oscillating air cylinder or electric linear motor (i.e. one that reverses automatically as it reaches its limit) thus eliminating the need for the drive pulley; however such cylinders and linear motors are not as commonly available as air or electric motors. In the future, however, they may become widely available and thus could be incorporated into this invention.
A further embodiment would be for smaller trucks and passenger automobiles. This would have the motor and drive pulley located inside the door panel and additional pulleys to guide the cable to the mirror. This embodiment would allow the wiper to work on a mirror that is longer than it is high, such as would be typical on an automobile. It would also allow this invention to be incorporated into a mirror assembly featuring both angle and tilt adjustment behind the mirror, as is common on more expensive automobiles. There are many ways to arrange the pulleys to accomplish this while adhering to the principles of this invention.
Another embodiment would utilize round guide rods instead of the thin blade guides shown in the drawings; this inventor built a prototype utilizing round guides as they were easier to fabricate with the machinery available. While consistent with the principles of this invention, this inventor believes that they are more obtrusive and more vulnerable to ice than the design shown in the drawings.
A third embodiment would be to have the wiper arm horizontal and vertically traversing the face of the mirror; but while that is not inconsistent with the principles of this invention this inventor does not favor this approach for reasons stated earlier.
