Fluid-flow pulsator

Claim 1

A fluid-flow pulsator comprising: a housing defining an internal chamber and having means defining an inlet and an outlet each communicating with said chamber, said inlet admitting said fluid under a predetermined substantially constant static pressure thereof and said outlet releasing said fluid from said chamber; means for supplying said fluid under said predetermined substantially constant static pressure; a piston assembly mounted for movement within said housing, said assembly including a first piston spaced a fixed distance during operation from a second piston effectively toward said outlet and with said first piston having a first area, exposed within said chamber to pressure of fluid introduced therein through said inlet, less than a corresponding second area of said second piston; means associated with said assembly for valvingly closing said outlet when said assembly is moved theretoward; means for resiliently urging said assembly in a direction effecting closure of said outlet with said first and second pistons effectively being disposed in said chamber on opposite sides of said inlet; said pressure within said chamber, the strength of said urging means and said areas being correlated to produce and are essentially determinative of the production of pulses of fluid from said outlet in response to a supply of fluid to said inlet, said pressure acting on said second area creating a first force tending to move said assembly in a direction to effect opening of said outlet, said pressure acting on said first area creating a second force tending to move said assembly in a direction to effect closure of said opening, the strength of said urging means acting on said second piston creating a third force tending to move said assembly in a direction to effect closure of said opening, and a fourth force tending to move said assembly in a direction to effect opening of said outlet with said fourth force equaling the sum of said second and third forces during closure of said opening but being created by said pressure acting on said first area during opening of said outlet; and said pressure, said strength and said areas being selected so that said assembly moves in the opening direction when said first force exceeds the sum of said second and third forces and moves in the closing direction when the sum of said first and fourth forces falls below the sum of said second and third forces existing upon opening of said outlet.