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Piezoelectric pump

Piezoelectric pump description/claims

This application claims benefit of the Japanese Patent Application No. 2007-035878 filed on Feb. 16, 2007, the entire content of which is hereby incorporated by reference.

1. Field of the Disclosure

The present disclosure relates to a piezoelectric pump that performs a pumping operation using vibrations of a piezoelectric vibrator.

2. Description of the Related Art

For example, JP-A-6-117377 and Japanese Utility Model Registration No. 2510590 disclose piezoelectric pumps including: a piezoelectric vibrator whose periphery is fluid-tightly sealed; a pump chamber and an air chamber that are provided on the front and rear sides of the piezoelectric vibrator; and a pair of check valves (including a check value that allows the flow of liquid to the pump chamber and a check valve that allows the flow of liquid from the pump chamber) that are provided on a pair of flow passages communicating with the pump chamber and allow liquid to flow in opposite directions. When the piezoelectric vibrator is vibrated, the volume of the pump chamber varies, which causes one of the pair of check valves to be opened and the other check value to be closed. This operation is repeated to perform a pumping operation. Such a piezoelectric pump has been used as, for example, a coolant circulating pump for a water-cooled notebook computer.

JP-A-2001-238291 discloses a unimorph type piezoelectric vibrator in which a piezoelectric element is laminated on one surface of a shim formed of a conductive thin metal plate. JP-A-6-203351 discloses a bimorph type piezoelectric vibrator in which piezoelectric elements are provided on both sides of the shim. Regardless of the type of piezoelectric vibrators, in the related art, a pair of ring-shaped sealing members (ring-shaped support members) come into contact with only the front and rear surfaces of the shim, and the piezoelectric element is arranged inside the ring-shaped sealing members, in order to fluid-tightly seal the piezoelectric vibrator. In this case, when the piezoelectric element being deformed (extended or contracted) is pressed, the piezoelectric element is not sufficiently deformed, which results in a reduction in the discharge amount of liquid and an instable pumping operation.

However, the following factors as well as the flow rate of liquid should be considered in the piezoelectric vibrator: high closing pressure (the internal pressure of a discharge passage (system) when intake and discharge umbrellas are closed (when no liquid flows)); and a high mechanical strength of the piezoelectric vibrator. That is, even when the internal pressure is at a high level, it is necessary to prevent the deformation of a piezoelectric vibrator and increase the closing pressure.

Embodiments of the present disclosure may provide a piezoelectric pump capable of improving the mechanical strength and support strength of a piezoelectric vibrator and increasing the closing pressure thereof while reducing the thickness of a shim.

According to an embodiment of the present disclosure, a piezoelectric pump may include: a piezoelectric vibrator including a main shim that is formed of a conductive thin metal plate and a piezoelectric element layer that is formed on the main shim; and a pair of ring-shaped support members that support front and rear sides of a circumferential portion of the piezoelectric vibrator such that a pump chamber and an air chamber formed on the front and rear sides of the piezoelectric vibrator are fluid-tightly sealed. The ring-shaped support members may support both sides of a circumferential portion of the piezoelectric element layer of the piezoelectric vibrator, and the piezoelectric vibrator may be vibrated to perform a pumping operation.

The piezoelectric vibrator may include one or more shims that are formed of an elastic metal material in a unimorph type or a bimorph type.

In the piezoelectric pump according to an embodiment of the present disclosure, in the piezoelectric vibrator, one surface of the main shim may abut on the pump chamber, and at least one piezoelectric element layer may be formed on the other surface of the main shim. In this example, one of the pair of ring-shaped support members close to the pump chamber may come into contact with a circumferential portion of the main shim, and the other ring-shaped support member close to the air chamber may come into contact with the circumferential portion of the piezoelectric element layer.

In the piezoelectric pump according to an embodiment of the present disclosure, the piezoelectric element layer of the piezoelectric vibrator may include: a lower piezoelectric element layer that is formed on the other surface of the main shim; and an upper piezoelectric element layer that is formed on the lower piezoelectric element layer so as to be electrically insulated from the lower piezoelectric element layer.

In the piezoelectric pump according to an embodiment of the present disclosure, in addition to the main shim, an intermediate shim formed of an elastic metal material having mechanical recovery may be interposed between a plurality of piezoelectric element layers of the piezoelectric vibrator. For example, the intermediate shim may have higher mechanical recovery than the main shim. When the intermediate shim has high mechanical recovery, the intermediate shim may easily be deformed with the displacement of a plurality of piezoelectric element layers, and may rarely hinder the deformation of the plurality of piezoelectric element layers.

In the piezoelectric pump according to an embodiment of the present disclosure, the intermediate shim may have a larger diameter than the piezoelectric element layer formed on the intermediate shim, and the pair of ring-shaped support members may support both sides of a circumferential portion of a laminate of the intermediate shim, the main shim, and the piezoelectric element layer interposed between the two shims. When the piezoelectric element layer of the piezoelectric vibrator is formed in, for example, a two-layer structure of the lower piezoelectric element layer and the upper piezoelectric element layer, the intermediate shim may have a larger diameter than the upper piezoelectric element layer, and may extend to a circumferential portion of the lower piezoelectric element layer. The support members may support both sides of a circumferential portion of the lower piezoelectric element layer with the intermediate shim interposed therebetween.

FIG. 1 depicts an expanded perspective view illustrating the basic structure of a piezoelectric pump according to an embodiment of the present disclosure;

FIG. 2 depicts a cross-sectional view illustrating the piezoelectric pump according to an embodiment of the present disclosure;

• Provisional Patent
• Utility Patent

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