US 3893903 A
A device for protecting the surface of a steel structure of a road vehicle from corrosion, comprising a galvanic anode, a permanent magnet carried by an inner side of the anode and connecting the anode to said surface, and spaced flange-like elongations projecting from at least one outer side of the anode and adapted to collect layers of dirt greater than layers of dirt built up upon exposed surfaces of the structure.
Description (OCR text may contain errors)
O Unlted States Patent 111] 3,893,903 Lindholm July 8, 1975  CATHODIC PROTECTION OF VEHICLES, 3,513,082 5/1970 Beer et a1. 204/197 ESPECIALLY MOTOR CARS FOREIGN PATENTS OR APPLICATIONS Inventor: J Lindholm, Malmvagen 12 4 6,503,715 9/1965 Netherlands 204/197 Sollentuna, Sweden 683,629 12/1952 United Kingdom..... 204/197 Filed: Feb. 1973 908,310 10/1962 UnIted Kingdom 204/197 [211 App]. NO: 334,906 OTHER PUBLICATIONS Justin, Official Gazette, Vol. 659, p. 590, Oct. 6, 1952.  US. Cl 204/197; 204/286; 204/297 M  Int. Cl. C23f 13/00 zmary ExammerT. Tung  Fleld of Search 204/147, 148, 196, 197,
204M289, 297 M Attorney, Agent, or Flrm Richards and Geler  References Cited  ABSTRACT UNITED STATES PATENTS A device for protecting the surface of a steel structure 1 374 976 4 1921 Allen et al. 204/289 of a mad vehicle from comprising a 1:900:011 3/1933 Durham... 204/197 vanic anode, a permanent magnet carried by an inner 2,760,636 8/1956 Johnson 204/197 side of the anode and Connecting the anode to said 3,047,478 7/1962 Marsh et a1 204/ 197 surface, and spaced flange-like elongations projecting 3,202,596 1965 ne 20 /197 from at least one outer side of the anode and adapted 3,260,661 7/1966 F P et v e 197 to collect layers of dirt greater than layers of dirt built 3,349,017 10/1967 Ziegler 204/197 up upon exposed Surfaces of the strucmm 3,361,656 1/1968 Miller 204/289 3,484,350 12/ 1969 Zaremski 204/148 1 Claim, 2 Drawing Figures 1 CATHODIC PROTECTION OF VEHICLES, ESPECIALLY MOTOR CARS It is well known from the ship building industry to attach a galvanic or zinc anode to the metal hull of a ship by means of an adhesive bonding or by bolts or screws.
It is well known to use base metals but also noble metals have been used.
Prior art has, however, not shown, that an active cathodic protection for vehicles, especially motor cars would be possible. Research in different countries has been carried on with the object to prevent or at least to reduce the different kinds of corrosion arising on the chassis of a motor car. So far a generally available method has not been found. I
The current strength required at electrically isolating coatings to obtain a satisfactory corrosion protection is less than 1 nA/m on the surface to be protected. Theoretically it would be possible to get far below that limit, but such method would never be used due to absurd costs and increase of weight, not to mention the maintenance costs of such method. The chassis of a conventional car has generally a underbody coating for protection from corrosion, but wear and aging of such coating makes it necessary to renew the coating at least once a year.
Object of this invention is to provide a simple, practical, inexpensive and efficient anode, easily attachable at the metallic surfaces of the chassis of motor cars reducing the necessity of maintenance of said coating. To create conditions for the electrochemical process within reasonable costs it is presupposed that such an anode is attachable on any motor car irrespective of model and kind. This requires a rather small anode body which can be attached to the metal irrespective of the shaping of the metal. The problem to create a satisfactory electrolyte on the anode is solved by giving at least one of the surfaces of the anode an irregular shape, preferably in form of flangelike elongations extending from the anode body. Such an improved anode secures moisture and moisture absorping compounds, e.g., road dirt to remain on the flangelike elongations of the anode which in turn creates the electrolyte required. Said compound and/or moisture causes a larger active surface for delivery of current.
This coating of road dirt, generally moist dirt, encompasses the anode or rather the anode is embedded in said moist road dirt. Thereby a long activity of the anode is secured. It is well known, that dry road dirt causes no or hardly no corrosion at all. The improved anode operates automatically as long as it is required, in other words, as long as there is any moisture or moist compound encompassing the anode. It would therefore be most advantageous to attache the improved anode at those localities of the metallic chassis where the thickest layer of road dirt normally is found.
The improved anode has an even surface to be attached to the metallic plate. Said surfaces can in a known manner be provided with an electrically conductive adhesive comprising fine metal particles.
Other advantages will appear from the following description of an example of the invention and the novel features will be particularly pointed out in connection with the appended claim.
In the accompanying drawing:
FIG. 1 is a perspective view of the improved anode,
2 and FIG. 2 is an end view of the anode in FIG. 1.
In accordance with this invention the anode l0 creates in a manner known per se galvanic separation of cations. This anode 10 can easily be made in handy sizes to fit any car. The anode 10 has even or substantially even surfaces 11, which serves as contact surfaces against the metallic plate, e.g., under the wings of a motor car. The anode 10 may be attached to the metallic plate by an adhesive bonding agent 14 having metal particles and well known in art. According to the invention, the anode 10 has a number of winglike elongated parts 12 extending downwards on at least one but preferably three surfaces of the anode body. These winglike parts 12 have a flangelike shape and the purpose is that moisture and moist road dirt shall create a compound coating between opposite flanges of the anode. In case the anode is attached under a wing of a car, road dirt will be thrown up towards the wings through the rotation of the wheels and cling to the flangelike parts 12 thereby securing the desired function of the anode. Instead of flangelike parts 12 the active surfaces of the anode 10 may have any irregular form, e.g., screens or the like serving the same purpose. To ensure that the anode 10 is satisfactory jointed to the metallic plate the upper part of the anode body may have a U-shaped recess in which a magnet 15 is arranged. The magnet itself or in combination with the aforementioned adhesive guarantees that the anode 10 is firmly secured to the metallic plate without any mechanical devices such as bolts and straps. Collection of moist substances is necessary in order to guarantee that the anode has always a thicker layer of dirt than the surfaces to be protected. The drying of this thicker layer requires more time than the drying of dirt layers on the surfaces to be protected, which means that the protection is effective always when last-mentioned layers are damp, and is terminated after the drying of these layers. The anode is thus moist a certain time period after the drying of the dirt on the surface to be protected, but is never dry before the completion of the drying of the last-mentioned surfaces. The protection is thus effective all of the time required, plus a certain marginal time.
It will be understood that various changes in the details, materials, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claim.
1. A device for protecting from corrosion a surface of a steel structure of a road vehicle, said device comprising a galvanic anode having a flat inner side and an outer side means carried by said inner side for attaching the anode to a surface section exposed to road dirt, said means including a permanent magnet connected to said anode, means for electrically connecting said anode with said structure, and means carried by said outer side for collecting road dirt, the last-mentioned means comprising spaced outwardly projecting parallel flange-like elongations extending on the outer side for collecting layers of dirt of greater thickness than those which would be deposited upon the unprotected surface of the steel structure.