JPH07151060A - Piezoelectric pump - Google Patents

Abstract

PURPOSE:To facilitate elimination of air inside a pump chamber in the case that driving is started from the vacant condition by fixing an outer peripheral part of a piezoelectric vibrator by means of a casing provided with a packing, and providing the piezoelectric vibrator with downward inclination from the discharge port side to the suction port side. CONSTITUTION:A piezoelectric vibrator 3 in a piezoelectric pump is prepared by applying electrodes on both surfaces of piezoelectric bodies, applying them to each other with their electrodes being trued up through phosphor bronze plates, and providing a lead wire for an ac current thereto. The piezoelectric vibrator 3 is sealed and supported by the inner peripheral surface of a casing through a fixing packing 4. The casing has a suction port 6 and a discharge port 6', respectively provided with check valves 2, 2'. In such a piezoelectric pump, a portion of an outer peripheral part of the discharge port 6' nearest the packing 4 is formed on a position located by 1mm from an inner end of the packing. A pump chamber has inclination of substantially four degrees, which chamber is prepared by the casing, the piezoelectric vibrator 3 and the fixing packing 4. The side of the discharge port 6 is et higher.

Description

Detailed Description of the Invention

[0001]

The present invention relates to medical equipment, industrial equipment,
The present invention relates to a piezoelectric pump used for physics and chemistry equipment.

[0002]

2. Description of the Related Art FIG. 1 is a sectional view showing the structure of a conventional piezoelectric pump. The piezoelectric hoop hermetically supports the outer peripheral portion of the piezoelectric vibrator 3 through a packing 4 for fixing provided on the inner peripheral surface of the casing 1, and applies an alternating voltage to the piezoelectric vibrator to apply the piezoelectric vibrator. By vibrating the suction port 6
Further, the suction check valve 2 is sucked into the pump chamber, and the fluid sucked into the pump chamber is discharged from the discharge port 6'through the discharge check valve 2 '. Further, the suction port 6 / discharge port 6'is attached to a position close to the central portion where the vibration of the piezoelectric vibrator is largest.

[0003]

In the above conventional pump, gas such as air is likely to be accumulated in the pump chamber surrounded by the casing, the piezoelectric vibrator and the fixing packing. This is because when the air escapes to a certain extent, the fluid that has entered through the suction port is discharged through the discharge port, and thereafter, the fluid is sent in a state where the air remains accumulated. In this way, when air is accumulated in the pump chamber, there arises a problem that the discharge pressure, which is a pump characteristic, is significantly reduced.

[0004]

In order to solve such a problem, the inventor of the present invention has made extensive studies, and as a result, completed the present invention.

That is, according to the present invention, the outer peripheral portion of the piezoelectric vibrator is sandwiched and fixed by a casing having a packing having a diameter corresponding to the vibrator, and a fluid suction port and a fluid discharge port are provided on one side of the casing. In a piezoelectric pump having outlets and suction and discharge check valves provided at the respective outlets, the position of the discharge port attached to the casing closest to the fixing packing is 5 m from the inner end of the fixing packing.
The present invention relates to a piezoelectric pump, wherein the piezoelectric vibrator is mounted within m and is provided with a downward inclination of 2 ° or more from a discharge port side toward a suction port side.

The present invention will be further described in detail.

The discharge port of the pump is preferably as close to the fixing packing as possible. Desirably, the outermost portion of the discharge port of the pump is attached to a position closest to the fixing packing within 0 to 5 mm from the inner end of the fixing packing. When the position closest to the fixing packing on the outer peripheral portion of the discharge port is provided at a position farther than 5 mm at the inner end of the fixing packing, when the pump chamber is driven from an empty state, air is discharged between the discharge port and the fixing packing. The amount of air that accumulates in the gap increases with distance from the packing, making it difficult to remove the air.

Further, it is preferable that the piezoelectric vibrator is provided with a downward inclination of 2 ° or more from the discharge port side toward the suction port side. In the state where the pump chamber is not inclined, when the pump chamber is driven from an empty state, the fluid flows into the discharge port before the air escapes, and the air remains.

The diameter of the suction port is preferably 3 mm or more. If the diameter is less than that, bubbles will be generated due to the force of the sucked fluid, and air will remain. A duck bill type, an umbrella type, or the like can be used as the check valve provided at each port.

As the piezoelectric body constituting the piezoelectric vibrator, ceramic type or organic type can be used. Specifically,
Examples of the ceramic type include lead titanate and lead zirconate titanate, and examples of the organic type include polyvinylidene fluoride.
More preferably, a piezoelectric plate having a dielectric constant of 3000 or more and an electromechanical coupling coefficient of Kp50% or more is bonded to both sides of the metal plate with the polarization directions aligned, and the diameter is 30 to 70 mm and the thickness of the vibrator is 1. 3 to 2.0 mm, capacitance is 150 to 2
It is preferable to have a characteristic of 00 nF. Since these piezoelectric vibrators are electrically insulated, an insulating coating material such as epoxy resin may be applied to the surface thereof.

[0011]

EXAMPLES The present invention will be described below with reference to examples.

FIG. 2 is a sectional view showing an embodiment of the piezoelectric pump of the present invention. In FIG. 2, the piezoelectric vibrator 3 is hermetically supported on the inner peripheral surface of the casing 1 via a packing 4 for fixing. In this embodiment, a transparent material such as acrylic is used for the casing to observe the movement of air. The piezoelectric vibrator 3 is one in which electrodes are applied on both sides of a piezoelectric body and the polarization directions are aligned and bonded via a phosphor bronze metal plate, and a lead wire 5 for applying an AC voltage is attached to the piezoelectric vibrator 3. Consists of.

By the way, in the present invention, the size and the like of the piezoelectric vibrator can be appropriately selected depending on the fluid used. Here, two piezoelectric elements having a permittivity of 3900 and an electromechanical coupling coefficient of Kp62%, which are machined by sintering a composite oxide composed of Pb, Zr, Ti, and La, are bonded via a phosphor bronze plate. I used one. The diameter was 50 mmφ, the thickness was 1.5 mm, and the capacitance was 180 nF.

A suction port 6 and a discharge port 6'are provided in the casing, and a suction check valve 2 and a discharge check valve 2'are attached to each of them.

In this embodiment, the outermost peripheral portion of the discharge port is attached to the innermost end of the fixing packing at a position 1 mm closest to the fixing packing, and is surrounded by the casing, the piezoelectric vibrator and the fixing packing. The pump chamber has an inclination of 4 ° so that the discharge port side is higher.

The pump was driven from a state where the pump chamber was empty, and the way of air escape from the inner peripheral portion of the fixing packing when water was introduced was observed. The result is shown in FIG. In addition, hereinafter, in FIG. 3 to FIG. 6, a portion where water exists is hatched,
The part where the air remains is shown in white.

COMPARATIVE EXAMPLE 1 All the same as in the example except that the outermost peripheral portion of the discharge port was located 20 mm inside the fixing packing at the position closest to the fixing packing, and the pump chamber was not inclined. did. The piezoelectric pump was driven to observe how air escaped when water was introduced. The result is shown in FIG.

COMPARATIVE EXAMPLE 2 A structure in which the position closest to the fixing packing on the outer peripheral portion of the discharge port is provided 20 mm inside the fixing packing, and the pump chamber is inclined at 20 degrees to increase the discharge port side. Except that, all were the same as in the example. The piezoelectric pump was driven to observe how air escaped when water was introduced. The result is shown in FIG.

Comparative Example 3 All were the same as in the example except that the outermost peripheral portion of the discharge port was provided at a position 1 mm from the inner end of the fixing packing closest to the fixing packing, and the pump chamber was not inclined. did. The piezoelectric pump was driven to observe how air escaped when water was introduced. The result is shown in FIG.

[0020]

According to the piezoelectric pump of the present invention, the air accumulated in the pump chamber can be removed even when driving is started from an empty state in the pump chamber, and the discharge pressure and the discharge amount can be prevented from lowering. It has become possible.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the structure of a conventional piezoelectric pump.

FIG. 2 is a vertical cross-sectional view showing the structure of the piezoelectric pump of the present invention.

FIG. 3 is a diagram schematically showing the remaining state of air in the pump chamber when the pump is driven from the state where air remains in the pump chamber and water flows into the pump chamber in the embodiment.

FIG. 4 is a diagram schematically showing a remaining state of air in the pump chamber when water is flown into the pump by driving the pump in a state where air remains in the pump chamber in Comparative Example 1.

FIG. 5 is a diagram schematically showing a remaining state of air in the pump chamber when water is flown into the pump by driving the pump from a state where air remains in the pump chamber in Comparative Example 2;

FIG. 6 is a diagram schematically showing a remaining state of air in the pump chamber when water is flown into the pump by driving the pump in a state where air remains in the pump chamber in Comparative Example 3;

[Explanation of symbols]

 1: Casing 2: Suction check valve 2 ': Discharge check valve 3: Piezoelectric vibrator 4: Fixing packing 5: Lead wire 6: Suction port 6': Discharge port

Claims (1)

[Claims] 1. A piezoelectric vibrator is fixed by sandwiching the outer peripheral portion of the piezoelectric vibrator with a casing fitted with a packing suitable for the diameter of the piezoelectric oscillator, and providing a fluid suction port and a fluid discharge port on one side of the casing. In a piezoelectric pump provided with a suction and discharge check valve for each of these, a position of the discharge port attached to the casing closest to the fixing packing is attached within 5 mm from the inner end of the fixing packing, A piezoelectric pump, wherein the piezoelectric vibrator is provided with a downward inclination of 2 ° or more from the discharge port side toward the suction port side.