1. Field of the Invention
The present invention relates to lubrication of a compressor lip seal. More particularly, the present invention concerns a reservoir and drainage system for adequately lubricating a compressor lip seal while not over-saturating the lip seal.
2. Background Art
Refrigeration systems, such as the type used in transport refrigeration equipment, include, in the simplest form, a compressor, a condenser, an expansion device and an evaporator serially interconnected to form a closed refrigeration circulation path. In systems that use a reciprocating type compressor, these systems must be lubricated by a lubricating oil which mixes with the refrigerant being compressed therein.
A typical reciprocating compressor includes a piston reciprocating within a cylinder for mechanically compressing gaseous refrigerant. Appropriate manifolds and valves are provided to allow gas to be drawn into the cylinder during the down stroke of the piston and to be compressed during the up stroke.
Oil is used in such compressors to lubricate the various parts and interfaces there between. To maintain refrigerant pressure within the compressor in an open drive configuration where the drive is external to the compressor, a mechanical shaft seal is used. The compressor oil pump deploys an oil film to seal against the leakage of pressurized gas and to lubricate the faces of the seal during operation. For example, mechanical shaft seals are used on the crankshaft of the compressor where the crankshaft exits the compressor crankcase in the vicinity of the gland plate. Crankshafts of such compressors may also employ additional seals, typically a lip seals, for keeping external contamination out of the compressor. Accordingly, lip seals are usually the last line of defense of the internal workings of the compressor and are external to the mechanical shaft seal and most typically located at the gland plate assembly.
In the prior art, lip seals have the tendency to prematurely wear, requiring compressor maintenance. Premature wear from friction between the crankshaft and the lip seal can lead to the intrusion of dirt into the compressor cavity, damaging the inner mechanisms of the compressor, and/or allowing excessive leakage of oil to the compressor exterior.
It is an object of the present invention to improve the life of compressor lip seals.
It is a further object of the present invention to provide a mechanism to lubricate compressor lip seals to increase lip seal life and reduce compressor maintenance.
It is another object of the present invention to lubricate but not over lubricate compressor lip seals by providing a mechanism for control over the amount of lubrication the lips seals receive.
It is another object of the present invention to provide a reservoir and drainage passage in the vicinity of a lip seal to provide adequate but not excessive lubrication thereto. incorporation with a refrigeration circuit within an air conditioning system or a refrigeration system it is to be understood that this method of oil collection, lubrication and diversion is equally applicable to other types of compressors, pumps and other applications.
Referring now to
Referring to
The crankshaft seal mechanism further includes a cylindrical body 44 formed from a resilient material, using oil between it and the crankshaft to act as a refrigerant seal. The spring 45 wrapped around the exterior of the body 44 and resting against the crankshaft seal thrust face 43 provides axial loading between the two shaft face seals 29 and 33. The two face seals are loaded such that, with the use of oil, they will act as a refrigerant seal. Due, however, to a pressure differential, oil passes across the two shaft face seal surfaces as they seal against refrigerant leakage, and excess oil collects in the seal cavity reservoir 41, and passes to the lip seal/crank-shaft interface when the oil level exceeds the reservoir capacity.
The invention as provided herein operates to utilize the transferred oil passed through the seal interface to lubricate and extend the life of the lip seal. Referring to
While the invention has been described in reference to a preferred embodiment and a particular type of compressor, it is to be understood by those skilled in the art that modifications and variations can be effected within the spirit and scope of the invention and the invention could be applied to different types of compressors or other mechanisms incorporating similar type shaft seals.