US 2988102 A
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June 13, 1961 G. W. HARRY ETAL MOISTURE BLOW-OFF VALVE Filed Sept. 11, 1958 Zap/ewe United States Patent O "ice 2,988,102 MOISTURE BLOW-OFF VALVE Gordon W. Harry, Flushing, and Earl W. Pierce, Flint,
Mich., assignors to General Motors Corporation, Detroit, Micl1., a corporation of Delaware Filed Sept. 11, 1958, Ser. No. 760,337 1 Claim. (Cl. 137-204) This invention relates to valves for removing impurities from air lines of pneumatic systems and more particularly to valves for removing moisture from compressed air systems supplying compressed air to pneumatic apparatus such as vehicle air suspension systems or pneumatic tools.
In the operation of pneumatic apparatus such as vehicle suspension systems using compressed air, difiiculties have been experienced because of the entrainment of moisture which causes malfunctioning of the valves and other parts of the systems. Difiiculties have become particularly apparent during cold weather. It is obvious that a simple and compact device for removing any entrained moisture from pneumatic systems is essential and that such a device should be rugged in construction and reliable in its use.
An object of the present invention is to provide an improved valve by means of which moisture may be removed from a compressed air system with a minimum of compressed air leakage.
To this end, a feature of the present invention is a valve with a pressure actuated portion of a diaphragm operated by differential air pressure forceably to eject moisture from a compressed air stream by-passing the actuated portion.
The above and other important features of the invention will now be described in detail in the specification and then pointed out more particularly in the appended claims.
In the drawing is depicted a cross-sectional view of a moisture blow-01f valve constituting an embodiment of the present invention.
The valve comprises a main body 10, a cover member 12 with a diaphragm 14 interposed between the two members and cooperating with the latter in defining an air inlet chamber '16 and an air outlet chamber 18. Bolts such as the bolt 19 are utilized to hold the valve together. A threaded air inlet port 20 is formed in the main body member and this port leads to a sintered metal filter element 22 tightly fixed within the body member 10 for separating dirt particles which may be directed through the port with the air supply. The upper interior portion of the main body member 10 is enlarged to enclose an annular chamber 24 herein considered as a portion of the air inlet chamber 16 as it is separated from the main portion of the air chamber 16 only by means of two semicircular deflectors or ridges. Only one ridge 26 is shown in the drawing but it will be appreciated that diametrically opposed passages are formed between the ridges to provide .a full and open communication between the annular chamber portion 24 and the main portion of the chamber 16. A small part of the chamber portion 24 is traversed by a web for a purpose to be described hereinafter.
The diaphragm 14 is so placed that its periphery or circular margin forms a seal between the main body member 10 and the cap member 12. The intermediate portion of the diaphragm may be flexed and constitutes a pressure actuated diaphragm portion 30 separating the air inlet chamber 16 and its annular portion 24 from the air outlet chamber 18.
A passage 34 is formed in the main body member 10 and through the Web 25 in such a way as to communicate with the main portion of the air inlet chamber 16 and of the passage 34 is arranged to communicate with an Patented June 13, 1961 opening 36 formed in the margin of the diaphragm 14 and also with a passage 38 formed in the cover member 12. The other end of the passage 38 communicates with a chamber 40 in the cap member 12 which encloses a normally closed spring and pressure actuated valve generally indicated at 42. The latter functions as a main air valve and is supported in such position that it faces the plane of the diaphragm 14 with a valve disc 44 urged downwardly into closed position by means of a spring 46. Details regarding this main air valve are not specifically given herein, but it will be understood that it is the type of one-way valve commonly used in diaphragm fuel pumps and other devices of like nature. The central portion of the diaphragm 14 is apertured to accommodate two clamping members 50 and 52. These two members are rigidly fixed together to clamp the inner margin of the diaphragm 14. The clamping member 50 has a central and upwardly projecting protuberance 54 which faces the underside of the valve disc 44 and is spaced from the latter when no air is passing through the blow-ofi valve. The opening 55 in the valve 42 is larger in diameter than the protuberance 54.
' The drawing shows the blow-off valve in its inoperative position (that is, when no compressed air is being used by the system) and a coil spring 56 is installed within the air outlet chamber 18 and bears downwardly against a shoulder 58 formed on the member 50 to hold a shoulder 60 of the clamping member 52 down against the upper rim of the semi-circular ridges or portions in the air inlet chamber. The valve 42 is then in its normally closed position.
The underside of the clamping member 50 is bored and threaded as at 62 tightly to receive the upper end of a rod 64. A washer 66 and a nut 68 are provided to make this attachment secure. The rod 64 is surrounded by a coil spring 70, the upper end of which bears against the underside of the nut 68 and the lower end of which bears against a washer 72 resting in a recess 74 formed on the top of a poppet-type valve 76. The latter is adapted to slide upon the rod 64 and is provided with a conical rubseat formed on the body member 10. The washer 72 serves to confine a sealing washer 82 within the valve 76 so that air is at all times prevented from escaping along the rod and through the valve 76.
A clearance 84 is provided between the periphery of the valve 76 and the wall of a lower reduced portion 16. The lower end of the rod 64 is provided with an octagonal head and the rod is surrounded by a piston-like valve 92 located within a blow-off port 94 leading from the bottom of the air inlet chamber 16. An O-ring 96 is held within a groove formed in the valve continuously to prevent air leakage between the coaxial walls of the port 94 and the valve 92. A clearance 98, however, is provided between the cylindrical walls of the bolt 64 and the bore leading through the valve 92.
The two independently movable valves 76 and 92 normally cooperate with the main body member 10 and the rod 64 in defining a closed annular blow-01f zone 100 extending around the rod.
In operating the valve and remembering that the purpose of the valve is to remove impurities and particularly moisture from an air line system, air is admitted under pressure and from the air supply by way of the port 20 with the removal of solid impurities by the filter 22 and the removal of moisture in the air chamber 16. The removal of the moisture is by virtue of the deflecting action of the ridges 26 which serve as bafiles and also by virtue of the capacity of the chamber 16 which promotes the dropping out of the moisture. The latter tends to gather at the lower end of the air inlet chamber 16 around the poppet type valve 76. This presupposes that air is passing asasno'a 3 through the blow-'oflf valve and to the system by way of the outlet port 32. If no air is called for by the suspension system or by any pneumatic tool served by the system in which the blow-01f valve is installed, no air passes from the chamber 18 by way of the port 32 even though communication between the chamber 16 and the chamber 40 is had by way of the passages 34 and 38. This is because the valve 42 is held in its closed position by means of the spring 46. As soon as air is called for, however, the'suspension system or pneumatic tool will demand air from the air outlet chamber 18. This will give rise to a reduction in pressure in that chamber with a consequent lifting of the diaphragm 30 and the displacement of the valve disc 44 by the protuberance 54. As a consequence, air will pass through the port 55 of the valve 42 and through the outlet chamber 18 and the port 32 to the point of use. When the demand for compressed air ceases, the pressure in the chamber 18 will risei.e., the differential pressure affecting the diaphragm 14 will cease to exist and the spring 56 will cause the parts to assume the positions shown in the drawing. Valve 42 will become closed.
When air is called for and the diaphragm 14 rises against the spring 56, the rod 64 rises with the diaphragm with the head 90 of the rod closing the clearance space or moisture discharge passage 98 The rod also carries the valve 92 upwardly until it seats at 99 against the lower-end of the valve 76 after which both valves 92 and 76 continue to rise. As a consequence, the valve 76 is lifted from its seat 80 and any moisture which may previously have settled at the lower end of the chamber 16 will run into the blow-oft zone 1011 and be temporarily retained therein. The design is such that the O-ring seal 96 never rises beyond a shoulder 101 formed on the main body. This is to prevent wear and abrasion of'the seal. 7
When the demand for compressed air ceases and the diaphragm 14 lowers and simultaneously lowers the rod '64, the spring 70 will again cause the valve 76 to .seat
and sufllcient air pressure will be retained within the zone 100 to expel any moisture therein to atmosphere through the discharge passage 98 and the port '94. It will be noted that at no time during the complete cycle of the valve is there a free passage for the escape of compressed air from the air inlet chamber 16 to atmosphere by way of the port 94. Such a passage is blocked either at 80 or 99 and, because of this feature, no compressed air is wasted despite the moisture ejection.
The bleed 39 is preferably utilized to insure blow-off of moisture by the valve despite possible limited use or prolonged non-use of compressed air by the system served. It is obvious that if the Water ejection was not sufliciently or periodically engaged in, the first demand on the system for compressed air may well find operation difficult. By means of the vent 39 the blow-oft valve maintains the system clear of moisture at all times. After 4 the'val've 44 is closed upon an initial downward'movement of the rod 64, it is possible that unequal air pressures will be exerted on opposite sides of the diaphragm 14 so that the latter and the valve 92 will not lower to discharge moisture. This difficulty would be due to a build-up of a pressure pocket in chamber 16. This being the case, a moisture blow-off passage would not be opened before air would again be required from the system. The vent 39, however, provides a means whereby the air pressures on opposite sides of the diaphragm 14 are slowly equalized during a period of non-use for the system with the result that the spring 56 is enabled to effect complete downward rod movement and moisture is discharged.
A moisture blow-oil valve comprising a main body member, a cover member, a diaphragm between said members and cooperating with the latter in defining an air inlet chamber in said body member and an air outlet chamber in said cover member, a port leading from each of said chambers, a pressure actuated portion of said diaphragm having a rod fixed thereto and depending therefrom, spring means in said outlet chamber urging-said pressure actuated portion downwardly, a passage in said valve extending around said pressure actuated portion and connecting said chambers, a main air valve controlling said passage, a moisture blow-off port leading from said air inlet chamber, two valves slidable on said rod and movable upwardly by the latter when a differential pressure exists between said inlet and outlet chambers, one of said two valves being a spring-loaded poppet type valve adapted to seat on said body member to close the port leading from the air inlet chamber when said difierential pressure is non-existent and said spring means is efliective, the other of said valves cooperating with said rod in defining a moisture discharge passage within said blow-ofi port and being arranged to seat on said one valve to close said discharge passage when said difierential pressure exists, said two valves and said main body defining a blow-ofi zone around said rod in communication with said discharge passage, and the arrangement being such that either one of said two valves is in closed position when the other of said two valves is in open position whereby no free communication-is had at any time between said inlet chamber and said blow-01f port.
References Cited in the file of this patent UNITED STATES PATENTS 2,619,106 Wilkerson Nov. 25, 1952 2,822,887 Engman Feb. 11, 1958 2,835,417 Kiraly May 20, 1958 2,869,570 Wilkerson Jan. 20, 1959