Design and experiments of a novel linear pump for fluid delivery applications requiring low flow pulsation driven by linear oscillating motor

Miniaturized pumps have extensive applications in biomedical, pharmaceutical industry, science research on chips, and thermal managements. Diaphragm type and piston type mechanical pumps rectified by flaky type check valve have been widely studied by researchers due to its simple structure and can be manufactured with small mechanical size. Many of the diaphragm type mini pumps are driven by smart materials like piezoelectric (PZT) and shape memory alloy. However, smart materials have small deformation rate which limits the flow rate of pump. Also, the check valve rectified diaphragm or piston pumps deliver fluids in a series of discrete small volumes, which generates flow pulsation. In order to solve these problems, this paper presents a novel linear pump named as collaborative rectification pump (CRP) to produce adequate flow and low ripple simultaneously. CRP incorporates two miniature cylinders to discharge fluid and two spool valves to rectify the fluid flow. Specifically, the CRP is driven by two linear oscillating motors, which are designed and optimized to generate reciprocating motion at high frequency with adequate stroke. With control of the stroke, frequency and phase difference between the two units, CRP is capable of discharging fluid in a continuous manner with theoretically zero ripple fluid delivery ability. Also, CRP offers the advantage of simple structure and ultimate flexibility in bi-directionally pumping. Performance of the CRP prototype is demonstrated through a series of simulation and experiments, which verifies the novel principle and achieves expected low ripple flow advantages.