Unibody bypass plunger with integral dart valve cage

Abstract

A bypass plunger formed as an integral one-piece hollow body-and-valve cage unit retains a dart valve within a valve cage section of the hollow body with a threaded retaining nut that may be secured by crimple means. A boundary zone, defined along the plunger body, where the integral valve cage section adjoins the plunger body, is configured with a uniform outer diameter to maximize the plunger body wall thickness and durability of the one-piece bypass plunger. The valve cage may have flow ports configured with ramps at an angle with the longitudinal axis to control flow through the flow ports during descent of the bypass plunger. A clutch assembly using garter springs with split bobbins may be disposed within the valve cage portion of the one-piece bypass plunger.

What is claimed is: 
     
         1 . A bypass plunger, comprising:
 a monolithic one-piece tubular plunger body having a first end, a second end, a valve cage section, a boundary zone, and a main body, wherein:
 the valve cage section includes the first end of the one-piece tubular plunger body and is between the first end and the boundary zone, 
 the valve cage section includes at least one flow port, 
 a ratio R of an outer diameter to an inner diameter of the valve cage section is approximately 1.52 or greater along substantially all of the portion of the valve cage across which a dart valve head travels, 
 the boundary zone is between the valve cage portion and the main body, 
 an exterior of the valve cage section is tapered such that the outer diameter of the valve cage section becomes smaller from a first outer diameter D 1  at the boundary zone to the first end of the plunger body, and 
 an internal valve seat conformably shaped to a profile of a dart valve head is positioned within the boundary zone. 
   
     
     
         2 . The bypass plunger of  claim 1 , wherein the valve cage section is configured such that the ratio R of the outer diameter to the inner diameter of the valve cage section is approximately 1.52 or greater along substantially an entire length of the valve cage section. 
     
     
         3 . The bypass plunger of  claim 1 , wherein the outside diameter D 1  where the valve cage section joins the boundary zone is substantially the same as an outside diameter D 2  where the boundary zone joins the main body. 
     
     
         4 . The bypass plunger of  claim 3 , wherein an outside diameter of the boundary zone does vary along a length of the boundary zone. 
     
     
         5 . The bypass plunger of  claim 1 , wherein the at least one flow port of the valve cage section comprises a plurality of flow ports that are arranged symmetrically around a circumference of the valve cage section. 
     
     
         6 . The bypass plunger of  claim 5 , wherein a central longitudinal axis of each of the flow ports forms an acute angle with respect to a central longitudinal axis of the valve cage section. 
     
     
         7 . The bypass plunger of  claim 1 , further comprising a dart valve assembly retained within the valve cage section. 
     
     
         8 . The bypass plunger of  claim 7 , wherein the dart valve assembly comprises:
 a dart valve having a cylindrical stem enlarged at a first end to form a dart valve head, the dart valve head having a sealing surface configured to seal against the internal valve seat; and   a clutch disposed within the valve cage and surrounding the cylindrical stem.   
     
     
         9 . The bypass plunger of  claim 8 , wherein the dart valve is configured to reciprocate within the valve cage section between a closed position where the dart valve head is in contact with the internal valve seat and an open position at which the dart valve head is disposed away from the internal valve seat. 
     
     
         10 . The bypass plunger of  claim 1 , wherein the valve cage section further comprises:
 a first internal threaded portion at the first end for receiving a first threaded retainer for retaining a dart valve assembly within the valve cage section; and   a second internal threaded portion between the first end and the internal valve seat for receiving a second threaded retainer for limiting movement of a dart valve within the valve cage assembly.   
     
     
         11 . The bypass plunger of  claim 10 , further comprising:
 a retaining nut having external threads that is mated to the first internal threaded portion of the valve cage section; and   a partition nut having external threads that is mated to the second internal threaded portion of the valve cage section.   
     
     
         12 . The bypass plunger of  claim 11 , further comprising:
 a clutch located between the retaining nut and the partition nut; and   a dart valve having a cylindrical stem enlarged at a first end to form a dart valve head, the dart valve head having a sealing surface configured to seal against the internal valve seat, wherein the cylindrical stem of the dart valve passes through internal bores of the retaining nut, the clutch and the partition nut, and wherein the dart valve head is located between the partition nut and the internal valve seat.   
     
     
         13 . The bypass plunger of  claim 11 , further comprising locking devices that are configured to lock the retaining nut and the partition nut to the valve cage section. 
     
     
         14 . The bypass plunger of  claim 13 , wherein the locking devices comprise at least one of a crimple, a pin, a key, and a set screw. 
     
     
         15 . The bypass plunger of  claim 13 , wherein the locking devices comprise crimples, each crimple comprising a deformed portion of material of the valve cage section that extends into an underlying relieved portion of the retaining nut or partition nut. 
     
     
         16 . The bypass plunger of  claim 1 , wherein the valve cage section comprises:
 a first internal threaded portion at the first end for receiving a first threaded retainer for retaining a dart valve assembly within the valve cage section; and   a partition disposed between the first internal threaded portion and the internal valve seat, wherein the partition is configured to limit movement of a dart valve within the valve cage section.   
     
     
         17 . The bypass plunger of  claim 16 , wherein the partition comprises a portion of an internal bore of the valve cage section having a reduced inner diameter. 
     
     
         18 . The bypass plunger of  claim 16 , further comprising:
 a clutch located between the retaining nut and the partition; and   a dart valve having a cylindrical stem enlarged at a first end to form a dart valve head, the dart valve head having a sealing surface configured to seal against the internal valve seat, wherein the cylindrical stem of the dart valve passes through internal bores of the retaining nut, the clutch and the partition, and wherein the dart valve head is located between the partition and the internal valve seat.   
     
     
         19 . A bypass plunger, comprising:
 a monolithic one-piece tubular plunger body having a valve cage section, a boundary zone, and a main body, the boundary zone being located between the valve cage section and the main body, wherein:
 the valve cage section comprises a hollow cylindrical wall having an outer diameter and an inner diameter, wherein at least one flow port extends through the hollow cylindrical wall, 
 a ratio R of the outer diameter of the hollow cylindrical wall to the inner diameter of the hollow cylindrical wall is approximately 1.52 or greater along substantially all of the portion of the valve cage section across which a dart valve head travels, 
 an exterior of the hollow cylindrical wall is tapered, and 
 an internal valve seat is positioned adjacent an end of the valve cage section and along the boundary zone. 
   
     
     
         20 . The bypass plunger of  claim 19 , wherein the valve cage section is configured such that the ratio R of the outer diameter of the hollow cylindrical wall to the inner diameter of the hollow cylindrical wall is approximately 1.52 or greater along substantially all of the valve cage section.