Patent Application
20080029343
The invention will be better understood from the following detailed description of the preferred embodiments thereof, taken in conjunction with the accompanying drawing, wherein like reference numerals refer to like parts, in which:
Before turning to the preferred embodiment, it should be understood that the present invention may take many forms in a variety of automotive assemblies employing a lubricant to lubricate moving parts. For illustrative purposes, throughout the following discussion the invention is described as it is incorporated into a particular magnetic device used in a specific product assembly, namely an electric motor 10 in the form of a stepper motor that provides linear actuation for an idle air control valve assembly.
With refence to
As shown in
In the embodiment of the motor 10 used in an idle air control valve, the shaft 30 has an integral pintle 32 at its distal end. A spring 34 tends to bias the pintle 32 in an extended position. The pintle 32 receives a cylindrical grime shield 36 to protect against contamination of the motor 10.
Certain parts of the motor 10 need to be lubricated. As noted above, the use of silicone based lubricants have caused failure of motors when operating at high temperate and/or in chemical or solvent exposed environments. Thus, in accordance with the embodiment, a perfluoropolyether (PFPE) based lubricant is employed in the motor 10. More particularly, a PFPE oil, preferably NYE Uniflor™ 8960, manufactured by Nye Lubricants, Inc. of Fairhaven, Mass. is used as a lubricant 38 to lubricate the rear bearing 20 encircled at D. In additon, PFPE grease, preferably NYE Uniflor™ 8961, manufactured by Nye Lubricants, Inc. is used as a lubricant 38′ to grease for example, the rotor and shaft threads encircled at A, the rotor and front bearing journal encircled at B, and the shaft and front bearing anti-rotate area, encircled at C. Other tradenames of suitable PFPE lubricants include Fombin®. Any PFPE based lubricant can be employed that can withstand greater than 200° C. temperature. In the embodiment, the PFPE lubricants 38, 38′ have a thermal functionality range of approximately −90° C. to +250° C. For automotive applications such as described, a functionality range of about −60 to +250° C. is accepatabe. PFPE lubricants are a completely fluorinated which provide thermal, chemical and oxidative stability. The use of a PFPE lubricant for the bearing oil eliminates the effects of fluids and temperature as found during testing.
Although the lubricants 38, 38′ were described for use in a motor 10 of an IACV, the lubricants 38, 38′ are equally applicable to other automotive assemblies that are exposed to temperatures above 200° C. and/or chemical or solvent exposed environments. For example, the lubricants 38, 38′ can be employed in extreme temperature applications that silicone cannot survive such as Exhaust Gas Recirculation (EGR) valves, radiator cooling fans, spark plug boots, etc. The lubricant can also be used in chemical or solvent exposed environments that silicone based grease does not survive or silicone based grease is not permitted such as evaporator purge valves, electronic throttle control, air control valves, fuel lever sensors, fuel systems in “flex” fuel vehicles, etc.
The foregoing preferred embodiments have been shown and described for the purposes of illustrating the structural and functional principles of the present invention, as well as illustrating the methods of employing the preferred embodiments and are subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within the spirit of the following claims.
This application claims the benefit of the earlier filing date of U.S. Provisional Application No. 60/821,483, filed on Aug. 4, 2006, which is hereby incorporated by reference into this specification.
| Number | Date | Country | |
|---|---|---|---|
| 60821483 | Aug 2006 | US |
