Patent Application
20090179170
The present invention pertains to valves that may be used for intake or outlet of gases or liquids for reciprocating compressors and pumps. The operative portion of such a compressor and pump includes at least one piston and cylinder assembly, and the intake and exhaust valves are typically located at or near one of the cylinder heads. It is commonly known to use the same form of valve for both inlet and outlet by simply reversing the position of the valve for the two uses. One such valve is disclosed in Inventor's prior U.S. Pat. No. 5,511,583 which has annular valve elements. The present invention differs in that the valve elements are not annular but cylindrical, have a semispherical seating surface and a matching semispherical element seating surface. Also, unlike U.S. Pat. No. 5,511,583 that has multiple springs per element and the present invention has a single spring per element biasing it closed, i.e. toward its seating surface in to and fro movement.
The present invention is similar to what is generally known as “poppet-type”. The valve elements of traditional poppet valves are more or less mushroom shaped, with the head of the mushroom defining the sealing surface for engagement with the valve seat, and the cylindrical stem of the mushroom being utilized for guidance of the valve element in its reciprocating movement. These valves elements lift is usually 0.250 inch or more from fully seated to full open in order to achieving low pressure drop. The high lift and large seat flow hole diameter provide a relatively large available flow area for the gases. Reducing the lift, as is often required in process market results in loss of efficiency. For this reason the traditional poppet valves are limited to low differential pressure and low speed applications. The present invention valve elements are different from traditional poppet valves in the following respects:
They are completely cylindrical without mushroom head.
The seating surface is semispherical.
The flow holes are smaller.
There are a greater number of flow holes.
The maximum lift area is equal to the flow hole area.
The above differences remove the limitations of traditional poppet valves.
A compressor and pump inlet or outlet valve according to the present invention comprises a seating plate and a guard plate removable attached in opposed relation to make up the valve body. The seating plate has a plurality of holes extending from an outer side of the seating plate to the inner side. The guard plate defines a respective stop surface generally opposed to but spaced from the seating surfaces associated with each seat hole. The guard plate also has flow passages from the inner to the outer side thereof and communicating with the spaces between the stop surfaces and the seating surfaces. A respective cylindrical valve element reciprocates between the stop surfaces and the respective opposed seating surfaces and have sealing surfaces sized and shaped to engage and seal against the respective seating surfaces. A single spring carried by the guard plate or valve element each engages a respective valve element to bias it toward the respective sealing surfaces. A replaceable ring with semispherical first seating surface in the seat plate significantly improves application possibilities and further reduces initial as well as future maintenance cost. This ring may be of almost any material including exotic material with minimal cost increases because low cost seat plate material may still be applied.
The cylindrical valve elements need not be fully customized, but can be off the shelf items, or made from off the shelf items, thereby decreasing production costs. Furthermore, a single size of cylindrical valve elements can be used not only throughout a given valve, but also for a range of valves of different sizes. Although inventor's prior U.S. Patent. No. 5,511,583 has performed well it is desirable to further upgrade and reduce manufacturing costs to meet new industry demands. The present invention addresses these needs by eliminating costly milling and further standardization of critical components.
Various objects, features and advantages of the invention will be made apparent by the following detailed description, the drawings, and the claims.
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