JPS6291675A - Micropump - Google Patents

Abstract

PURPOSE:To make it possible to control the flow accurately with the driving frequency by furnishing permanent elastic thin plates with the part processed in a convex and a displacement generating device installed connecting to the thin plates, to a micropump to convey a minute amount fluid. CONSTITUTION:This pump has valves 1 and 2 variable in the direction of arrows at the inlet and the exit respectively, and the operations of the valves 1 and 2 are controlled by stoppers 5. Furthermore, between the inlet and the exit, convex form thin plates 3 and 4 of a permanent elastic metal such as elinvar are arranged, to each of which is connected an end of an expansion device consisting of a piezoelectric actuator element 10 between a pair of parallel square plates 9. By a displacement to pull the thin plates 3 and 4 in the direction to increase the pumping volume through applying power to the piezoelectric actuator element 10, the valve 1 is opened to inhale the fluid, and then, by restoring the thin plates 3 and 4 through decreasing the power application, the valve 2 is opened to discharge the said fluid.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a micropump applied to medical equipment and chemical analysis equipment.

(Prior Art) Conventionally, micro pumps have been mechanical pumps that have a mechanism in which a vinyl pipe or the like is deformed by applying pressure from the outside, and fluid is transported by an amount equal to the volume reduction caused by the deformation.

Alternatively, in the case where all piezoelectric ceramics are used, the piezoelectric baymorph elements are arranged facing each other, and the fluid between the two bimorph elements is eliminated by displacing the bimorph elements in opposite phases.

(Problems to be Solved by the Invention) In the case of mechanical micropumps, it is difficult to accurately control the transported flow rate, as is clear from the principle of operation. If the device used is not driven at a resonant frequency, the amount of displacement of the bimorph is small, so the flow rate transported becomes extremely small.

Also, it is difficult to control it freely and completely.

An object of the present invention is to provide a micropump that solves this problem.

(Means for Solving All Problems) The present invention is a micropump comprising a constant elastic thin plate, a part of which is processed into a convex shape, and a displacement generating means stacked in contact with the thin plate. .

(Function) In the present invention, a stack of piezoelectric actuators that are displaced using a piezoelectric longitudinal effect, a piezoelectric actuator that uses a transverse effect, or an electrostrictive effect element is mounted on a constant elastic metal thin plate partially processed into a convex shape. Being crucified. When a relatively large flow t is desired to be obtained, a mechanism for mechanically controlling the entire displacement of the actuator is installed. As is well known, a convex plate has bistable positions. Therefore, when a trigger for displacement is given to the convex thin plate by the expansion and contraction of the piezoelectric actuator, it will be displaced all at once to a stable position.

As a result, the flow rate removed in one drive is kept constant. Furthermore, by changing the drive frequency of the piezoelectric actuator, the displacement period of the convex thin plate can be appropriately selected. In other words, it is possible to control the flow rate. However, it is clear that it is meaningless to drive the actuator at a cycle shorter than the time required for the Humpex-like thin plate to completely complete its displacement. Therefore, accurately, the flow t can be controlled in steps within this period.

(Example) FIG. 1 is an overall sectional view showing a configuration example of the present invention. At the inlet and outlet of the pump, there is a valve 1 that moves in the direction of the arrow.
, 2 is attached. The movements of the valves 1 and 2f'' are restricted by stoppers 5, respectively.

When the inlet valve It's convex thin plates 3 and 4 are displaced in the direction of decreasing the pump internal volume, V'i is sealed, and when the convex thin plate 3 is displaced in the direction of increasing the pump internal volume, it is freed. It acts on

Outlet valve 2fi acts in the opposite manner to the above, and fluid flows only in one direction from these valves 1 and 2.

Next, the fluid transport mechanism section will be explained. At a position displaced in the direction of reducing the internal volume of the 3゜4ri pump's convex-shaped thin plate made of a constant elastic metal such as Erimba, 1, without applying an electric field to the piezoelectric actuator, glue the tip of the expansion mechanism to the convex thin plates 3 and 4. . Then, when an electric field is applied, the piezoelectric actuator expands and the distal end of the expansion mechanism is displaced so as to pull the thin plates 3 and 4 in the direction of increasing the internal volume of the pump. At this time, valve 1 opens and fluid flows in. (At this time, the valve 2 is sealed.) When the applied electric field is then returned to zero, the tip of the expanding mechanism completely displaces the convex thin plates 3 and 4 so as to reduce the internal volume of the pump.

At this time, valve 1 is sealed and valve 2 is opened, allowing fluid to be discharged. This series of operations realizes the function of a pump.

Here, the displacement magnification mechanism will be explained. FIG. 2 shows a sectional view of a configuration example. The pressing element is sandwiched between the square members 9 arranged in parallel and is fixed.

The principle is as follows. According to this principle, the displacement Δl generated by applying an electric field to the piezoelectric actuator element 10 is magnified via the fulcrum information 6.

Expansion mechanism tip 7 glued to convex thin plates 3 and 4
, 8, the magnitude of Δl is about 8 μm when the entire electric field of IK displacement is applied in the case of a laminated piezoelectric actuator exploded by the green sheet method (shape: 2x3x9tn, 115 μm between two layers). 1
2/ll may be adjusted to the desired flow rate.

Here, the entire thin plate including the convex part is 20x20
xO,l t wx, The convex part is a spherical surface with a radius of curvature R = about 156 gates, and the box fjr covering the pump drive section is a cube of 20 x 20 x 20 m.

At this time, assuming that the flowing fluid is an incompressible fluid, and assuming that the volume change is all used to remove the fluid, the amount transported by one cycle of driving is about 12-. Multiplying this by the drive frequency will give you a huge flow rate per second.

It goes without saying that the pump function can be achieved with just one convex thin plate 3.

Further, in the embodiment, an example of a displacement magnifying mechanism using an actuator as the displacement generating means is shown, but it is also possible to use only the actuator.

(Effects of the Invention) As described above, it is possible to precisely control the flow rate in steps depending on the drive frequency.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of the overall configuration of a micropump according to the present invention, and FIG. 2 is a cross-sectional view showing an example of the configuration of a displacement magnifying mechanism. In the figure, 1 and 2 are valves, 3 and 4 are convex thin plates, 5 is a stopper, 6 is a fulcrum shaft, 7 and 8 are the tips of the expansion mechanism, and 9
is square material, 102 actuator element 1 Figure 5, stocker

Claims (3)

[Claims] (1) A pump for transporting a minute amount of fluid, characterized by comprising a constant elastic thin plate partially processed into a convex shape, and a displacement generating means attached in connection with the thin plate. pump. (2) The micropump according to claim 1, wherein two constant elastic thin plates are arranged facing each other. (3) The micropump according to claim 1 or 2, wherein the displacement generating means is an actuator or a displacement magnification mechanism incorporating an actuator.