Valve-less fluid control circuit for rhythmic action devices

A circulatory assist device comprising a fluid control circuit for controlling rhythmic action devices, said fluid control circuit comprising a plurality of pressure sensitive fluid oscillators coupled together in a ring configuration for circulating a fluid, wherein each of said fluid oscillators comprises:

• an input conduit having a first end for receiving a working fluid;
• an interactive region communicating with a second end of said input conduit;
• a resistance conduit having a first end communicating with said interactive region;
• capacitance chamber means for storing the working fluid and for providing a peristaltic pumping of the working fluid, said capacitance chamber means communicating with a second end of said resistance conduit;
• an exhaust conduit communicating with said interactive region;
• a first control conduit for controlling a direction of the flow of the working fluid entering said interactive region, said first control conduit communicating at a first end with said capacitance chamber means and at a second end with said interactive region, so as to provide an output path of the working fluid pumped from said capacitance chamber means, said first control conduit communicating with said interactive region at an angle relative to said input conduit so that when a fluid pressure of the working fluid in said first control conduit reaches a certain predetermined level relative to the fluid pressure in said input conduit, said first control conduit controls a flow direction of the working fluid entering said interactive region from said input conduit, so as to direct the flow toward said exhaust conduit;
• and wherein said fluid control circuit further comprises coupling means for coupling said plurality of fluid oscillators together so that an output from the exhaust conduit of each fluid oscillator is coupled to the input conduit of a successive one of said fluid oscillators in said ring configuration, so that the working fluid circulates successively through the respective capacitance chambers of said fluid control circuit without valves, and wherein said capacitance chamber means of each of said fluid oscillators comprises expandable sleeve means for wrapping around at least a portion of a limb of a patient, and said sleeve means of said plurality of fluid oscillators are coupled to each other so that the sleeve means expand and contract successively in said plurality of fluid oscillators as the working fluid circulates through said fluid control circuit.