WINDSCREEN WIPER BLADE

Abstract: Windshield wiper blade made of such substance mixture from which material comes off forming a membrane on the windshield surface when the blade gets hot and the blade is rubbing against the windshield surface. In addition, the blade has an electric resistance to heat the blade.

Description: WINDSCREEN WIPER BLADE This invention concerns a windshield wiper blade. US patent specification 1 915 775 discloses a windshield wiper blade containing material effecting such treatment of the windshield surface that rain drops are prevented from forming upon it. A problem with this prior blade is that material treating the windshield surface constantly works loose from the blade. For this reason, the blade "dries" very quickly, so that no material for treating the windshield surface will be left in its pores. Windshield wiper blades provided with a heating element are also known. Such blades are described, for example, in US patent specification 2 656 448 and in international publication WO 89/04781. A windshield wiper blade in accordance with the present invention is characterized by the following combination: the blade is made of such substance mixture from which material comes off forming a membrane on the windshield surface as the blade gets hot and as the blade is rubbing against the windshield; and the blade is provided with an electric resistance to heat the blade. By providing the blade with a heating element it is possible to control the coming off of the material forming a membrane. The material forming a membrane is made to come off the blade by means of heating, when the previous layer on the windshield begins to wear off. However, the material does not come off the blade constantly. This means that there is sufficient membrane-forming material to last the whole useful life of the blade. The blade may be made of rubber or of a rubber-like thermoplastic elastomer by extrusion moulding. The elastomer is preferably polycarbonate or some silicone-based material. Pieces equal in length to the blade are then cut out from the extruded product. Upon cooling, the finished blade is flexible and elastic, being at the same time of suitable hardness. An electric resistance is arranged within the blade. The material added to the mass is preferably some silicone- based oil or oils. This remains in the pores of the finished blade. When heating and using the blade, material will come off from it in a plastic condition. Some materials suitable for this purpose are the liquid silicones LR 3088/30-60 and 5 LR 3089/50+70 made by Wacker-Chemie. Silicone oil AP 500 made by the same manufacturer may be added 1 - 4 % to the compound. When heating the resistance in the windshield wiper blade according to the invention, the blade surface temperature will rise to approximately 60°C. As the moving blade is at the same 10 time rubbing against the windshield, silicone oil will come off from it. This oil forms a protecting membrane on the windshield surface which also prevents the lights of oncoming vehicles from blinding the driver. The membrane repels dirt and water. Thus there is no need to add any separate liquid i s detergent to the washing water of the windshield wiper, but one may use just plain water or water to which only an anti¬ freeze agent is added. Material will come off from the blade for as long as the blade is in a useful condition even in other respects. 20 When the blade is also heated by an electric resistance, it is very useful also in cold weather, effectively preventing washing liquid from freezing onto the windshield. Even if the windshield is damaged and scratched during use by e.g. sand hitting it, transparency of the windshield is 25 nevertheless almost as good as with a new unused windshield, since a surface membrane has been formed on it by the material coming off the blade. The membrane remaining on the windshield will not come off even when washing the car in an automatic washing device. 30 In drizzly rain, a windshield wiper usually spreads out the drops over the windshield, however, without removing the layer of dirt, so that visibility will become very poor. But the membrane formed by the blade in accordance with the invention makes small drizzle drops remain as drops without spreading 35 out over the windshield. Thus, the wiper need not be used until more water has collected onto the windshield surface. When in cold weather water drops gather on the windshield surface and freeze in spite of everything, even they will keep their drop-like shape, whereby they can be much more easily removed from the windshield than a thin layer of ice which has spread out evenly. Visibility through the windshield remains good even when the rain is subcooled.

Claims: Claims 1. A windshield wiper blade, characterized by the following combination: the blade is made of such substance mixture from which material comes off forming a membrane on the windshield surface when the blade gets hot and when the blade is rubbing against the windshield; and the blade is provided with an electric resistance to heat the blade. 2. A windshield wiper blade in accordance with claim 1, characterized in that the material forming the membrane contains silicone. AMENDED CLAIMS [received by the International Bureau on 30 May 1996 (30.05.96); original claim 1 amended; remaining claim unchanged (1 page)] 1. (Amended) A windshield wiper blade, characterized by the following combination: the blade is made of such substance mixture from which material comes off forming a membrane on the windshield surface when the blade gets hot and when the blade is rubbing against the windshield; and the blade is provided with an electric resistance to heat the blade and to prevent formation of ice. 2. A windshield wiper blade in accordance with claim 1, characterized in that the material forming the membrane contains silicone.

Inventors: VORNANEN KEIJO, VORNANEN, KEIJO
Applicants: VORNANEN KEIJO, VORNANEN, KEIJO
Application year: 1996
Main classification: B60S1
IPC codes: B60S1