Clearance pocket assembly
United States Patent 11 1 Ashton 1 Apr. 22, 1975 CLEARANCE POCKET ASSEMBLY [75] lnventor: Robert Ashton, Houston, Tex.  
 [73] Assignee: lngersoll-Rand Co., Woodcliff Lake,  
 [22] Filed: July 16, 1973 [21] Appl. No.: 379,498  
 [52] [1.8. CI 92/60.5; 417/275 [51] Int. Cl. F0lb 31/14 [58] Field of Search 417/275, 276, 277; 92/605; 251/304 [56] References Cited UNITED STATES PATENTS 100,113 2/1870 Brccden 251/304 1,333,617 3/1920 Harkins 251/304 1,364,059 12/1920 Jones 251/304 1,579,782 4/1926 Ricsncr 417/275 1,621,913 3/1927 Longacrc... 417/275 1,867,681 7/1932 Simson 92/605 1969507 8/1934 Gchrcs.... 417/275 3,045.892 7/1962 White 92/605 3,295,748 1/1967 Lcitgeb 92/605 3,618.475 11/1971 3.655.301 4/1972 McClung 92/605 FOREIGN PATENTS OR APPLICATIONS 757,030 12/1933 France 251/304 809,548 2/1959 United Kingdom... 920.710 3/1963 United Kingdom 251/304 Primary Examiner-William L. Freeh Assistant Examiner-G. P. LaPointe Attorney, Agent, or FirmBernard J. Murphy [57] ABSTRACT An assembly that converts a standard cylinder outer head, having a clearance passageway formed therewithin, to a fixed volume clearance pocket outer head. The assembly comprises a gate valve having cooperating butterfly-shaped plates or elements operative, across the innermost portion of the clearance passageway of a standard cylinder outer head, by a rotatable valve shaft-engaging collar disposed external of the passageway.  
 4 Claims, 6 Drawing Figures PATENTEDAPR22|975 suamn z PRIOR ART CLEARANCE POCKET ASSEMBLY This invention pertains to clearance pocket assemblies for altering a cylinder of a compressor, or the like, to some fixed volume clearance, and in particular to a clearance pocket assembly for converting a standard cylinder outer head to a fixed volume clearance pocket outer head.  
  Most oil field and process cylinders have a clearance bottle connection in the cylinder outer head with a plug in the clearance passageway. Typically, the plug is shortened or removed, or replaced with a clearance bottle. When a fixed volume clearance pocket is required a replacement outer head, having a more intricate patternand casting, which has a clearance cavity and a mechanical valve therein must be installed in substitution for the standard outer head. It is an object of this invention to teach the use of standard heads even when fixed volume clearance pockets are required.  
  Another object of this invention is to set forth a clearance pocket assembly, for replaceable and operative installation thereof within the clearance passageway of a standard, cylinder outer head of a compressor or the like, comprising, valving means for insertion thereof into the clearance passageway, said valving means being selectively operative for opening and closing the clearance passageway to the admittance thereinto of fluid; means coupled to said valving means for replaceably fastening the latter to the outer head; and means coupled to said valving means for operating the latter.  
  A feature of this invention comprises an assembly that converts a standard cylinder outer head to a fixed volume clearance pocket outer head. The assembly comprises a gate valve having cooperating butterflyshaped plates or valve elements operative, across the innermost portion of the clearance passageway of a standard cylinder outer head, by a rotatable valve shaft-engaging collar disposed external of the passageway. Further objects and features of this invention will become more apparent by reference to the following description taken in conjunction with the accompanying figures, in which:  
  FIG. 1 is a cross-sectional view of a priorart standard cylinder outer head, with a plug secured in the clearance passageway;  
  FIG. 2 is an enlarged cross-sectional view of the standard cylinder outer head of FIG. 1 showing an embodiment of the novel clearance pocket assembly replaceably fixed therewithin, the view taken along section 2-2 of FIG. 3;  
  FIG. 3 is an end view of the cylinder outer head and clearance pocket assembly of FIG. 2;  
  FIG. 4 is an enlarged, fragmentary view of the valve shaft sealing and keying arrangement;  
  FIG. 5 is an enlarged plan view of the shaft nut and locking tab arrangement, with the stress-relieving set screw shown in cross-section and FIG. 6 is an isometric, exploded view of the valve elements and shaft, the view taken from the left side of FIG. 2, and being enlarged over the scale of FIG. 2. As shown in the figures, the assembly 10 employs a gate valve 12, having cooperating butterfly-shaped valve elements which is lubricated by the atomized mist in the cylinder 14 of a compressor, for instance. There is a slight clearance between the outer diameter D of the valve 12 and the bore B in the clearance passageway 16 of the standard outer head 18. Peripheral sealing is dynamic, arising from an orifice choke effect. The assembly valve shaft 20 has O-ring seals 22 thereabout, within an end cover 24 bolted to head 18.  
  The innermost end of the shaft 20 is welded to the innermost butterfly-shaped valve element 26, while the outermost end of the shaft is keyed, at 28, to a shaft collar 30. The other, cooperative butterfly-shaped valve element 26&#39; is welded to the innermost end of a shaft-enveloping sleeve 34, and the opposite end of the sleeve is welded to the end cover 24. Thus, with rotation of shaft collar 30, valve 12 is opened or closed, selectively. As shown in FIG. 2, the valve is in a closed position.  
  Adjustment of tension in the shaft 20, to prevent valve chatter. is accomplished by means of a threadedly engaged shaft nut 36. Shaft nut 36 is tightened onto the threaded end of the shaft 20, approximately to an optimum torque valve. Then an adjustable, notched locking tab 38 is used to secure the nut 36 against vibrationinduced loosening. Tab 38 (FIG. 5) has an aperture bounded by notches 39 which in number are twice as many as the fiat-junctures of nut 36, and has a pair of fastener holes 38&#39; formed therein. Tab 38 is placed on and about nut 36 so that a hole 38&#39; is in near proximity to a corresponding tapped hole 38&#34; in collar 30. By slightly torquing (or untorquing) nut 36, the selected hole 38&#39; is aligned with tapped hole 38&#34;, and then a fastener is emplaced-to secure both the tab 38 and the nut 36 thereat. Set screw 40 is used to take out all the slack in the assembly 10, once the proper adjustment is made. Further, this feature is incorporated to prevent fatiguing of the threads of the shaft 20. The assembly 10 is subjected to cyclic stress in one direction and, typically, this would give rise to early mortality of the threads which join nut 36 and shaft 20. To relieve this uni-directional nut/shaft stress, set screw 40 is provided. It is threaded into the portion of nut 36 which the end of shaft 20 does not occupy, and then is torqued against the shaft end to effect the nut/shaft stress relief.  
  The shaft collar 30 has an arcuate slot 42 which receives a cap screw 44. This is a safety feature which prevents the shaft collar 30 and shaft 20, etc., from blowing out of the assembly 10 should the shaft 20 break for any reason. So also, this screw 44 locks the assembly 10 open or closed when tightened. A doweltype handle 45 fixed to the collar, manipulates the latter.  
  The amount of fixed clearance can be adjusted by means of adding, or reducing the length of, clearance pocketsplit spacers 46 which are bolted to the end cover 24.  
  What I have disclosed is a simple, welded, valve operative clearance pocket assembly which can convert any standard cylinder head, with an adequate clearance passageway to a fixed volume outer head. The gas seal is dynamic and the valve is self lubricating, the latter comprising a butterfly-shaped set of elements 26 and 26&#39;. The shaft seals 22 and secured actuating mecha&#39; nism provide maximum safety.  
  While I have described my invention in connection with a specific embodiment thereof it is to be clearly understood that this is done only by way of example and not as a limitation to the scope of my invention as set forth in the objects thereof and in the appended claims.  
 I claim:  
  1. Affixed volume clearance pocket assembly. for replaceable and operative installation thereof within the clearance passageway of a standard, outer head of the cylinder of a compressor or the like, for varying the volume of the cylinder, the latter having a prescribed volume, comprising:  
 valving means for insertion thereof into the clearance passageway, said valving means being selectively operative for opening and closing the clearance passageway to communication with the cylinder volume and for the admittance thereinto of fluid from the cylinder;  
 means coupled to said valving means for replaceably fastening the latter to the outer head; and  
 means coupled to said valving means for operating the latter; wherein said valve operating means includes a shaft, and a rotatable element coupled to one end of said shaft for effecting rotation thereof;  
 said valving means is operatively engaged with the other end of the shaft;  
 said shaft has an axial length greater than that of said clearance passageway to effect a disposition of said rotatable element external of said clearance passageway;  
 said valving means comprises a gate valve, having a stationary element and a movable element;  
 said movable element is integral with said shaft;  
 said stationary element and said shaft are concentrically arranged and effect relative rotation therebetween;  
 said fastening means includes means for holding said stationary element at said innermost end of said passageway in a stationary disposition;  
 said holding means includes an elongate shaft sleeve, said stationary element is integrally fixed to one end of said sleeve, and a cover plate for replaceable fastening thereof across the outermost end of said passageway to the outer head;  
 said plate being integrally fixed to the other end of said sleeve, and having a borehole formed therein for a throughgoing penetration therof by said shaft;  
 said plate has a bearing surface;  
 said rotatable element has a bearing surface; and  
 said bearing surfaces together define an interface for relative rotation therebetween; further including means for securing said rotatable element against rotation; and wherein said rotatable element has an arcuate slot formed therethrough; and  
 said securing means comprises a headed fastener in penetration of said slot and threadedly secured to said plate.  
 2. An assembly, according to claim 1, wherein:  
 said valving means comprises means for opening and closing said clearance passageway only at an innermost end thereof.  
 3. An assembly, according to claim 1, wherein:  
 said shaft is rotatably disposed within said sleeve.  
 4. An assembly, according to claim 1, further including:  
 means engaged with said shaft manipulatable for tensioning said shaft.