초록 ▼

A check valve is provided to maintain fluid flow in a single desired direction through a conduit. The check valve requires a greater fluid pressure to open the check valve to allow fluid to pass in a desired direction than an amount of pressure required to keep the check valve in its open position.

A check valve is provided to maintain fluid flow in a single desired direction through a conduit. The check valve requires a greater fluid pressure to open the check valve to allow fluid to pass in a desired direction than an amount of pressure required to keep the check valve in its open position. This variable opening force performance is provided by providing a closure arm exerting a closure force on a flapper urging the flapper toward its closed position. Contact between the closure arm and the flapper occurs between a follower on the closure arm and a cam surface on the flapper. A contour of the cam surface on the flapper, and especially a hump on the cam surface causes the closure arm to exert a variable amount of force on the flapper depending on the position of the flapper. When the flapper is closed a relatively large amount of force is exerted on the flapper. When the flapper is open a relatively smaller amount of force is exerted on the flapper by the closure arm. The dimensions and contours of the follower and the cam surface can be customized to provide desired closure arm force exerting characteristics for the check valve of this invention.

대표청구항 ▼

A check valve is provided to maintain fluid flow in a single desired direction through a conduit. The check valve requires a greater fluid pressure to open the check valve to allow fluid to pass in a desired direction than an amount of pressure required to keep the check valve in its open position.

A check valve is provided to maintain fluid flow in a single desired direction through a conduit. The check valve requires a greater fluid pressure to open the check valve to allow fluid to pass in a desired direction than an amount of pressure required to keep the check valve in its open position. This variable opening force performance is provided by providing a closure arm exerting a closure force on a flapper urging the flapper toward its closed position. Contact between the closure arm and the flapper occurs between a follower on the closure arm and a cam surface on the flapper. A contour of the cam surface on the flapper, and especially a hump on the cam surface causes the closure arm to exert a variable amount of force on the flapper depending on the position of the flapper. When the flapper is closed a relatively large amount of force is exerted on the flapper. When the flapper is open a relatively smaller amount of force is exerted on the flapper by the closure arm. The dimensions and contours of the follower and the cam surface can be customized to provide desired closure arm force exerting characteristics for the check valve of this invention. of calibrating a focused beam of energy in a solid freeform fabrication apparatus by detecting and eliminating a non-optimal condition present in propagation characteristics of the focused beam, the propagation characteristics established by beam conditioning optics, the method comprising: directing the focused beam of energy to a profiling stage on the apparatus, the profiling stage receiving the focused beam of energy having substantially the same propagation characteristics used by the apparatus when forming a three-dimensional object; taking a first set of at least two measurements indicative of a beam width of the focused beam of energy at the profiling stage, the first set of measurements associated with a first planar position orthogonal to a propagation axis of the focused beam of energy; shifting the propagation characteristics of the focused beam of energy respectively with the profiling stage along the propagation axis of the focused beam by a first relative distance; taking a second set of at least two measurements indicative of the beam width of the focused beam of energy at the profiling stage, the second set of measurements associated with a second planar position orthogonal to the propagation axis of the focused beam of energy; shifting the propagation characteristics of the focused beam of energy respectively with the profiling stage along the propagation axis of the focused beam by a second relative distance; taking a third set of at least two measurements indicative of the beam width of the focused beam of energy at the profiling stage, the third set of measurements associated with a third planar position orthogonal to the propagation axis of the focused beam of energy; producing beam propagation data from the sets of measurements taken in each of the planar positions and the first and second relative distances; analyzing the beam propagation data to detect a non-optimal condition of the beam; producing at least one response when a non-optimal condition is detected; delivering the response to the beam conditioning optics; and adjusting the beam conditioning optics upon the delivery of the response to substantially eliminate the non-optimal condition. 16. The method of claim 15 wherein the step of taking the first set, the second set, and the third set of measurements further comprises: providing at least one sensor at the profiling stage; moving the focused be