Abstract Adjacent discrete plunger sections having alternate right and left hand spiral threads are loosely fitted on a cylindrical mandrel, one end of which has a threaded valve cage with a ball and seat therein, a shoulder section being threadedly engaged with the other end of the mandrel. The plunger sections are compressed by further increasing rotational pressure to the threaded shoulder section. Plunger sections are essentially nylon (polyamide) having a fiber glass filler material. Because of the creep of the material, end compression is applied in an amount which causes a squeeze of approximately 1/32 inch per foot of plunger section to purposely induce creep in the manufacturing process. After approximately 24 hours, during which the material creeps about 75 percent of its one year creep, the plunger assembly is centerless ground to the desired outside diameter. In addition to the discrete plunger sections being alternately right and left hand threaded, each section has its end portion unthreaded. The unthreaded end portion provides for pressure change and also a space for sand to fall out. The use of the unthreaded section and the alternately changing thread directions causes flow reversals and turbulent flow conditions which reduce slippage rate and increases the efficiency of the pump. The alternate right and left hand portions reduce the torque in the system and also reduce the flow rate through the spiral by causing direction changes.
In a pump plunger assembly having an elongated cylindrical body, said body having a longitudinal bore therethrough, and a valve assembly mounted internally to and co-axial with the body, the improvement comprising: said body having at least two discrete, abutting cylindrical thermoplastic sections mounted thereon, one of said at least two sections having a right hand spiral thread and another of said sections having a left hand spiral thread, each of said sections having an end-sealing abutting relationship with its adjacent section or sections, said body further having compression means thereon to secure said thermoplastic sections in a fixed position on said body and hold said sections continuously under compression.
Claim 2
Dependent Claim
110 words
In a pump plunger assembly having an elongated cylindrical body, said body having a longitudinal bore therethrough, and a valve assembly mounted internally to and co-axial with the body, the improvement comprising: said body having at least two discrete, abutting cylindrical thermoplastic sections mounted thereon, one of said at least two sections having a right hand spiral thread and another of said sections having a left hand spiral thread, each of said sections having an end-sealing abutting relationship with its adjacent section or sections, said body further having compression means thereon to secure said thermoplastic sections in a fixed position on said body and hold said sections continuously under compression.
Claim 3
Dependent Claim
26 words
In the assembly according to claim 1, being further characterized by at least one of said sections having an unthreaded end portion on its cylindrical surface.
Claim 4
Dependent Claim
26 words
In the assembly according to claim 2, being further characterized by said at least one section having both of its ends unthreaded on its cylindrical surface.
Claim 5
Dependent Claim
26 words
In the assembly according to claim 1, being further characterized by all of said sections having both of their ends unthreaded on their cylindrical surfaces, respectively.