Pump

Abstract

A pump according to the present invention has a circular diaphragm 4 placed at the bottom of a casing 2. At the bottom of the diaphragm 4, a piezoelectric element 6 is installed in contact with the diaphragm 4. A narrow space between the diaphragm 4 and the top wall of the casing 2 constitutes a pumping chamber 8. An inlet flow path 12 and an outlet flow path 14 are open to the pumping chamber 8, wherein a check valve 10 is installed in the inlet flow path 12. Immediately downstream of the pumping chamber, the outlet flow path 14 has a narrow segment 16. The narrow segment 16 of the outlet flow path has 1 / 2 the diameter and 1 / 4 the cross sectional area of the outlet flow path 14. The outlet flow path 14 has a return inlet 22, which is connected to a return outlet 23 in the inlet flow path via an active valve 24. The active valve 24 is opened and closed freely by an actuator 26 made of shape-memory alloy.

Description

technical field [0001] This invention relates to a positive displacement pump which moves fluid by changing the volume of its pump chamber with a piston or diaphragm, and more particularly to a pump with high flow rate and high reliability. Background technique [0002] Conventionally, such a typical pump has check valves installed between the inlet flow path and the variable-volume pump chamber, and between the outlet flow path and the pump chamber, for example in Japanese Patent Laid-Open No. 10-220357 described in . [0003] Meanwhile, as described in Japanese Patent Laid-Open No. 08-312537, for example, a pump that generates unidirectional flow by utilizing viscous resistance is constructed so that when a valve installed in the outlet flow path is opened, the fluid resistance in the inlet flow path greater than the fluid resistance in the outlet channel. [0004] Furthermore, for example, as described in the National Publication of International Patent Application No. ...

AI Technical Summary

Problems solved by technology

However, since the structure described in Japanese Patent Laid-Open No. 08-312537 mentioned above allows only low-frequency operation, it cannot realize a miniaturized, high-efficiency pump

[0007] Furthermore, in the case of the pump described in the national disclosure of International Patent Application No. 08-506874, since it is constructed to produce a one-way net flow rate of fluid flowing through the compression assembly equal to the increased and decreased volume of the pump chamber, as the flow The change of direction causes the pressure to drop, and the return flow increases with the increase of the external pressure (load pressure) on the outlet side, causing the pump to fail to operate at high load pressure

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