Fluid feed pump, fluid circulation device, medical device and electronic device

Abstract

A fluid feed pump is configured, such that a fluid is fed from an outlet channel of the fluid feed pump through an outlet buffer chamber to a fluid channel. The outlet buffer chamber is designed to have a higher compliance than a compliance of a pump chamber. The driving period of the fluid feed pump is set to a shorter period than a time constant defined by the compliance of the pump chamber and a flow resistance between an inlet of the outlet channel and an outlet of the fluid channel. This enables the fluid to be fed with high efficiency by taking advantage of the pressure oscillation occurring between the pump chamber and the outlet buffer chamber.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present application claims priority to Japanese Patent Applications No. 2011-199122 filed on Sep. 13, 2011; No. 2011-199127 filed on Sep. 13, 2011; No. 2011-252355 filed on Nov. 18, 2011; and No. 2012-55330 filed on Mar. 13, 2012, the disclosures of which are hereby incorporated by reference in their entireties.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a fluid feed pump operated to pressure-feed a fluid, as well as a fluid circulation device, a medical device and an electronic device.[0004]2. Description of Related Art[0005]A fuel feed pump of one proposed structure repeats the operation of increasing the volume of a pump chamber to suck in a fluid and subsequently decreasing the volume of the pump chamber to pressure-feed the fluid (e.g., JP 2011-103930A). This fluid feed pump pressure-feeds the fluid in the pump chamber, every time the volume of the pump chamber is increased and...

AI Technical Summary

Benefits of technology

The invention is a small pump that can efficiently cool down electronic devices by circulating a fluid through them. It has a high capacity for fluid feed, which allows for a smaller pump to be used. This design enables a more compact electronic device to be created.

Problems solved by technology

This results in pressure-feeding the fluid in the pump chamber through the outlet channel and thereby lowers the internal pressure of the pump chamber.

When a fluid channel connected with the outlet channel has high flow resistance (as in the thin and long fluid channel) or when a fluid of high viscosity is pressure-fed, it takes a relatively long time to flow the fluid corresponding to the excluded volume out of the pump chamber having the reduced volume.

This results in extending the time required for lowering the internal pressure of the pump chamber.

This means that a longer time is required to pressure-feed the fluid corresponding to the excluded volume.

This lowers the efficiency of fluid feed per cycle.

Even when the fluid channel does not have the high fluid resistance and the pressure-fed fluid does not have the high viscosity, the extremely short period of driving the fluid feed pump (i.e., the time per cycle of changing the volume of the pump chamber) (i.e., high driving frequency) may cause similar problem.

Even when the fluid channel does not have the high fluid resistance and the pressure-fed fluid does not have the high viscosity, it is impossible to fully flow the fluid corresponding to the excluded volume out of the pump chamber at the instance of expanding the piezoelectric element.

It takes not long but still some time to fully flow out the fluid corresponding to the excluded volume.

Driving the fluid feed pump in the shorter period than the time required to fully flow out the fluid corresponding to the excluded volume thus disadvantageously lowers the efficiency of fluid feed.

Driving the fluid feed pump in the shorter period than the time required to fully flow the fluid corresponding to the excluded volume out of the pump chamber (i.e., the time required to sufficiently reduces the internal pressure of the pump chamber) lowers the efficiency of fluid feed, irrespective of the flow resistance of the fluid channel and the viscosity of the pressure-fed fluid.

At the driving frequency of higher than 1 / τ, there is a significant decrease in efficiency of fluid feed by the fluid feed pump.

Such a decrease in efficiency of fluid feed indicates an increase in potential loss of the electrical energy applied to the piezoelectric element.

The pressure oscillation occurring between the pump chamber and the outlet buffer chamber via the outlet channel results in increasing the amount of the fluid supplied to the pump chamber.

The fluid feed pump of this embodiment immediately lowers the internal pressure of the pump chamber irrespective of the flow resistance of the fluid channel, and additionally interferes with attenuation of the pressure oscillation occurring between the pump chamber and the outlet buffer chamber.

When the compliance of the outlet buffer chamber is not sufficiently higher than the compliance of the pump chamber, the flow resistance of the fluid channel connected with the outlet buffer chamber may affect the pressure-feed of the fluid from the pump chamber to the outlet buffer chamber.

Using the piezoelectric element applies a large force to abruptly reduce the volume of the pump chamber, so that large pressure oscillation occurs between the pump chamber and the outlet buffer chamber.

For example, the light source of a projector generates large amount of heat and is thus required to be cooled down.

The excessively high compliance of the outlet buffer chamber extends the time until the expected fluid feed amount is fulfilled after start of the operation of the fluid feed pump.

For example, the light source of a projector generates large amount of heat and is thus required to be cooled down.

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