| 摘要 |
<p>A poppet valve comprises a tubular one-piece body (12) having flange means (30) on the exterior thereof, and a downward-facing valve seat (56) at the bottom interior thereof, with a valve guide spider (38) thereabove. A dome-shaped poppet valve (14) seats on the aforesaid valve seat, and has coaxially secured thereto an upwardly extending stem bolt (16) which protrudes through and above the valve body guide spider. A spring (18) disposed about the stem bolt biases it upwardly, acting on the top surface of the spider and on a lower surface of a spring retention cap (20) secured to the top of the stem bolt. In such a manner, the poppet valve is biased into engagement with the valve body seat at the lower end of the valve assembly. The poppet valve may be employed in a section of casing or in a guide shoe to form a float collar or float shoe, respectively, wherein the valve assembly is secured in place by a cement sheath (24).</p> |
