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  Drain valve assembly for use in an air compressor systemUSPTO Application #: 20070264135Title: Drain valve assembly for use in an air compressor system Abstract: The present air compressor system includes an inlet connected to a compression stage, a cooling stage having an inlet connected to an outlet of the compression stage and having an outlet passage; a drain valve having an liquid inlet in and adjacent a bottom of the outlet passage of the cooling stage to drain condensation when opened; and a controller controlling the compression stage and the drain valve. (end of abstract)
Agent: Barnes & Thornburg LLP - Washington, DC, US Inventors: Michael Hartl, William B. McCurdy USPTO Applicaton #: 20070264135 - Class: 417243000 (USPTO) Related Patent Categories: Pumps, With Intercooler The Patent Description & Claims data below is from USPTO Patent Application 20070264135. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND AND SUMMARY OF THE INVENTION [0001] The present disclosure relates generally to air compressors and more specifically to a drain valve for an air compressor. [0002] An air compressor, for example, two-stage air compressors include a first low pressure compression stage connected through an inter-cooling stage through high pressure compression stage whose output is provided through an after cooling stage to an air reservoir. Any condensation is generally removed at the air reservoir as indicated, for example, in FIG. 1 of U.S. Pat. No. 6,027,311 and U.S. Pat. No. 4,453,893. Each of the compressor stages produces a pressure dew point that is higher than atmospheric dew point. Condensation occurs when the output of the cooler drops temperature below the pressure dew point. If the condensation is not removed at temperatures above freezing, the moist air will cause problems in the elements after the cooler. This is particularly critical in the inter-cooling stage wherein the air is input into a second compressor stage. If condensation is not removed at or below freezing, the moisture can potentially block the exit of the cooling stages. This is also true at the output of the final or after cooling stage. [0003] One suggestion, as described in U.S. Pat. No. 6,952,932, is to bypass the after cooling stage such that gases are used to heat the cooled gases when ambient temperatures is at or below freezing, and are used downstream from the after cooling stage when moisture freezes in the after cooling stage. [0004] It is well-known in the multistage air compressors to have unloading valves at the output of the inter-cooling stage as illustrated by U.S. Pat. No. 6,287,085 and at the output of the after cooling stage as illustrated in U.S. Pat. No. 4,819,123. [0005] The present air compressor system includes an inlet connected to a compression stage, a cooling stage having an inlet connected to an outlet of the compression stage and having an outlet passage; a drain valve having a liquid inlet in and adjacent a bottom of the outlet passage of the cooling stage to drain condensation when opened; and a controller controlling the compression stage and the drain valve. [0006] A liquid inlet of the drain valve is at the lowest point in the outlet passage. The liquid inlet may be an end of a siphon tube in the outlet passage of the cooling stage. The drain valve includes an air port connected to the outlet passage of the cooling stage whereby air passing from the air port to the drain through the open drain valve educes liquid from the outlet passage of the cooling stage through the siphon. The air port is higher than an end of the siphon connected to the outlet passage of the cooling stage. [0007] The system may include first and second compression stages and the cooling stage is the inter-cooling stage. The cooling stage is connected to an outlet of the first compression stage and the outlet passage of the cooling stage is connected to an inlet of the second compression stage. The drain valve may be connected between the inter-cooling stage and the second compression stage. Alternatively, the drain valve may be connected to the after cooling stage which is connected to the outlet passage of the second compression stage. [0008] A drain valve assembly for an air compressor system includes a housing having a passage extending between a first port and a second port; a valve chamber having a liquid inlet in and adjacent a bottom of the passage and having a drain outlet; a valve seat in the valve chamber between the drain outlet and the liquid inlet; and a valve element responsive to an input signal to cover and uncover the valve seat. [0009] The liquid inlet may be an end of a siphon tube in the passage. The valve chamber includes an air port connected to the passage whereby air passing from the air port to the drain outlet through the open valve seat educes liquid from the passage through the siphon. The air port is higher than an end of the siphon connected to the passage. The valve seat is higher than the liquid inlet. [0010] Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0011] FIG. 1 is a perspective view of a compressor system according to the prior art. [0012] FIG. 2 is a perspective view of a drain valve assembly for an inter-cooling stage according the present disclosure. [0013] FIG. 3 is a cross-sectional view of a drain valve assembly taken along lines 3-3 of FIG. 2. [0014] FIG. 4 is a partial cut-away side view of a drain valve assembly for an after cooling stage according the present disclosure. [0015] FIG. 5 is a schematic of a compressor system according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT [0016] A piston compressor of the prior art is illustrated in FIG. 1 as a two-stage compressor unit 10. A drive unit 12 is mounted thereto and may be, for example, an electric motor. The crankcase 13 includes three piston cylinders 14a, 14b, and 14c. The first stage of compression includes piston cylinders 14b and 14c receiving air through filter 15. The second high-pressure stage is performed by piston cylinder 14a. The compressor unit 10 includes a cooling system 16 having an output 17 of the compressed air. Output 17 is generally connected to a reservoir 90 (shown in FIG. 5). [0017] The cooling system 16 for the two-stage compressor includes an inter-cooling stage 20 and an after cooling stage 22. The inter-cooling stage 20 has an inlet (not shown) connected by pipe 24 from the outlet of piston cylinders 14b and 14c to the inter-cooling stage 20. Outlet 25 of inter-cooling stage 20 is connected via outlet passage 26 to the inlet of the second stage piston cylinder 14a. The output of the second stage piston cylinder 14a is connected via pipe 28 to an inlet of the after cooling stage 22. [0018] As previously discussed, condensation will collect in the inter-cooling stage outlet passage 26, as well as exiting from outlet 17 of the after cooling stage 22. This collected condensation will freeze at lower temperatures and impede the operation of the compressor. [0019] A drain valve assembly 30, illustrated in FIG. 2 or 3, is designed to be connected between the outlet 25 of the inter-cooling stage and the inlet passage 26 of the high pressure stage of piston cylinder 14a. This would replace pipe 26 of FIG. 1 and be connected at the lower plugged outlet 27 of the inter-cooling stage 20, shown in FIG. 1. The drain valve 40 includes a housing 32 having a passage 38 between ports 34 and 36. Flanges 33 and 35 are provided to connect the ports 34 and 36 to the inter-cooling stage and the second stage compressor, respectively. Appropriate fasteners perform the connection. Housing portion 32 includes a drain valve 40 accessible via cover 39. [0020] By connecting port 34 of passage 38 at the lower outlet 27 of the inter-cooling stage, the bottom 37 of passage 38, which is an extension of the outlet passage of the inter-cooling stage 20 outlet, is below the inlet to the compressor stage 14a. Thus, this part of the passage 38 is the natural collection point for all condensation in the inter-cooling stage 20 outlet passage. The area adjacent the drain valve 40 is lower than the ports 34 and 36 to form a well to collect the condensation. [0021] The drain valve 40 includes a valve chamber 42 which includes a valve seat 44 mounted therein. Valve element 46 covers and uncovers the valve seat 44 to open and close the drain valve. An air inlet 48 connects the passage 38 to the valve chamber 42. A liquid inlet 50 is at the end of a tube 52 which is also connected to the valve chamber 42. Tube 52 forms a siphon as will be described. The end or the liquid inlet 50 is in the passage 38 and adjacent the bottom 39 of the passage 38. It should also be noted that the liquid inlet 50 is below the height of the valve seat 44. The air inlet 48 is above the valve seat 44. Alternatively, the valve seat 44 may be below the liquid inlet 50 and the tube 52 being replaced with a passage in the wall of the passage 38 connecting the passage 38 to the valve chamber 42. A drain sleeve 54 is threaded into opening 56 of the housing 38 below the valve seat 44. Continue reading... Full patent description for Drain valve assembly for use in an air compressor system Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Drain valve assembly for use in an air compressor system patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Drain valve assembly for use in an air compressor system or other areas of interest. ### Previous Patent Application: Control valve for variable displacement compressor Next Patent Application: Reciprocating piston machine Industry Class: Pumps ### FreshPatents.com Support Thank you for viewing the Drain valve assembly for use in an air compressor system patent info. 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