Variable displacement pump

Abstract: An actuator for a self-adjusting pump head assembly has a variable position pump shoe slidably attached to a base. The assembly pumps liquids through a tube in a peristaltic pump, including a translator of rotational motion into linear motion and a crank for automatically compensating for the manufacturing tolerances of the tube in the pump pivotally attached to the translator and the shoe. The crank for automatically compensating has a linkage or pair of links, carrying a helical compression spring, pivotally anchored to the translator and the shoe. The peristaltic pump includes a self-adjusting pump head, including a variable position pump shoe slidably attached to a base and a control for positioning, locking and applying a continuous reaction force on the shoe to compress the tube between the shoe and at least one roller located on the periphery of a mandrel. Thus the control further has the translator of rotational motion into linear motion, and the crank for automatically compensating for the manufacturing tolerances of the tube introduced into the pump, pivotally attached to the translator and the shoe. Alternatively the pump has a disposable manifold safety cartridge, removably attached to the base, to which ends of the tube attach. The cartridge has an asymmetrical tie bar keyed onto the base to insure that the cartridge is oriented in an acceptable manner and that the tube will be properly installed on the pump.

Abstract: A small, accurate, reliable and economical pump which is particularly useful in intravenous (IV) feeding includes a disposable pump chamber and a pump housing. The disposable pump chamber has an inlet, an outlet, and first and second flexible rolling diaphragm pumping chambers. First and second cylinders in the pump housing are positioned to receive the first and second flexible rolling diaphragms of the disposable pump chamber. First and second pistons are movable in the first and second cylinders, respectively. In addition, first and second valves are provided in the pump housing. The first valve controls fluid flow between the inlet and the first flexible rolling diaphragm pump chamber, while the second valve controls fluid flow between the first flexible rolling diaphragm pumping chamber and the second flexible rolling diaphragm pumping chamber. A motor and cam shaft drive the first and second pistons and the first and second valves. The first and second valves are controlled so that one valve is closed at all times, thereby providing fail safe operation of the pump.

Abstract: A new planar fluid pump based on the valve-less diffuser/nozzle pump principle is presented. The pump consists of two pump chambers, each with two flow rectifying diffuser/nozzle elements with rectangular cross sections, one at the inlet and one at the outlet. The pump chambers are arranged in parallel for high pump flow. Each pump chamber has two piezoelectrically vibrated diaphragms. The planar pump is fabricated in brass with a total thickness of 1 mm. The pump chamber diameter is 13 mm and the diffuser/nozzle element neck dimensions are 0.3×0.3 mm. Simplified theoretical analyses of the maximum pump flow and resonance frequency are given. The flow rectifying ability of the diffuser/nozzle elements is demonstrated in a stationary flow situation and the pump performance is verified in two different pump mode configurations: anti-phase and in-phase chamber volume excitation. The measurements in the anti-phase mode show pump flows and pump pressures which are more than twice as high as those of the in-phase oscillation mode. The anti-phase mode has a pump capacity of about 16 ml/min and a maximum pump pressure of about 1.7 m H2O with the pump diaphragm vibration frequency set to the pump resonance frequency of 540 Hz.

Abstract: Various “contactless” bearing mechanisms including hydrodynamic and magnetic bearings are provided for a rotary pump as alternatives to mechanical contact bearings. In one embodiment, a pump apparatus includes a pump housing defining a pumping chamber. The housing has a spindle extending into the pumping chamber. A spindle magnet assembly includes first and second magnets disposed within the spindle. The first and second magnets are arranged proximate each other with their respective magnetic vectors opposing each other. The lack of mechanical contact bearings enables longer life pump operation and less damage to working fluids such as blood.