JP3460301B2 - Piezo pump - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to medical equipment, industrial equipment,
The present invention relates to a piezoelectric pump used for a physics and chemistry equipment. 2. Description of the Related Art FIG. 1 is a longitudinal sectional view showing the structure of a piezoelectric pump of the type most used at present. The piezoelectric pump hermetically supports an outer peripheral portion of a disk-shaped piezoelectric vibrator (hereinafter, referred to as a vibrator) 6 via a fixing gasket 7 provided on an inner peripheral surface of the casing 1. Is applied to vibrate the vibrator, whereby fluid is sucked from the suction port 2 through the suction check valve 4 into the pump chamber 9, and the fluid sucked into the pump chamber 9 is discharged through the discharge check valve 5. 3 is discharged. [0003] Since electrodes are exposed on the surface of the vibrator 6, an insulating layer 8 is formed to secure electrical insulation and to protect the vibrator from a fluid. Also,
Ball valves and duckbill type valves have been used as check valves. [0004] Piezoelectric pumps are expected to be applied to various fields because of their small size and light weight as compared with conventional pumps. In order to enable the transfer of a fluid or the like, it is strongly desired to further improve the force, in particular. In general, the pump performance is very closely related to the performance of the vibrator, and the amplitude and the generated force, which are the performance values of the vibrator, greatly affect the discharge flow rate and the discharge pressure of the pump. The force generated by the vibrator is defined by the magnitude of the external force required to cancel the displacement of the vibrator caused by the application of the DC voltage. In order to improve the discharge pressure of the pump, the force generated by the vibrator is required. It is presumed that it is effective to improve The force generated by the vibrator is proportional to the applied voltage, the thickness of the vibrator, and the piezoelectric constant of the piezoelectric ceramic material.However, no significant improvement in the piezoelectric constant of the piezoelectric ceramic material over conventional materials can be expected, and the applied voltage Boosting leads to an increase in the current generated by the vibrator, causing large heat generation during driving.
Further, the vibrator may be damaged. Therefore, in practice, it is effective to use a vibrator whose thickness is increased to increase the generating force in order to improve the discharge pressure of the pump. However, in the piezoelectric pump of the conventional structure, even if the thickness of the vibrator is increased, the obtained discharge pressure of the pump does not increase so much.
It has been difficult to increase the discharge pressure of the pump by using a high-power vibrator. [0006] On the other hand, when the piezoelectric pump is driven by a commercial power supply, the valve used conventionally does not open or close following the driving frequency of 50 Hz or 60 Hz of the piezoelectric vibrator, so that fluid leakage occurs and discharge occurs. It was found that the pressure was reduced. In view of the above situation, the present inventors have conducted intensive studies to obtain a piezoelectric pump having a high discharge pressure, and have 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 provided with a packing corresponding to the diameter of the vibrator, and a fluid suction port and a fluid discharge port are provided on one side of the casing. In a piezoelectric pump in which outlets are provided and a pump chamber is formed by providing suction and discharge check valves in each of them, a piezoelectric pump in which a piezoelectric vibrator is covered with a resin film having a thickness of 0.3 mm or less, a piezoelectric pump, The outer peripheral portion of the vibrator is sandwiched and fixed by a casing fitted with a packing corresponding to the diameter of the vibrator, and a fluid suction port and a fluid discharge port are provided on one side of the casing. In the piezoelectric pump provided with a discharge check valve to form a pump chamber, the opening pressure (pressure at which the valve opens with a positive pressure) of the suction and discharge check valves is 0.01 kg / cm ² or less, and Withstand pressure (to reverse pressure Can withstand pressure) 1kg / cm
A piezoelectric pump characterized by using an umbrella type valve having ^two or more characteristics, and the outer peripheral portion of the piezoelectric vibrator is sandwiched and fixed by a casing fitted with a packing corresponding to the diameter of the vibrator. A fluid suction port and a fluid discharge port are provided on one side of the casing, and a suction and discharge check valve is provided in each of these to form a pump chamber. In the piezoelectric pump, openings are provided in the suction and discharge check valves. An umbrella type valve having a pressure (pressure at which the valve opens with positive pressure) of 0.01 kg / cm ² or less, and a pressure resistance (pressure at which the valve can withstand reverse pressure) of 1 kg / cm ² or more, and The present invention relates to a piezoelectric pump, wherein the center of the umbrella type valve is located on the diameter of the piezoelectric vibrator, and the umbrella portions of the valve overlap each other via the pump chamber wall surface. Hereinafter, the present invention will be described in detail. In the present invention, the piezoelectric vibrator has a thickness of 0.1 mm.
Coated with a resin film of 3 mm or less. One feature is that it is insulated. By satisfying this condition, it is possible to improve the discharge pressure by transmitting the generated force of the vibrator to the fluid without loss while protecting the fluid and securing the electrical insulation. When the insulating layer is thicker than 0.3 mm, it is possible to increase the discharge pressure of the pump by making the vibrator thinner, but as the impedance of the vibrator decreases, the heat generated during driving increases and eventually Since this causes damage to the vibrator, the range in which the discharge pressure can be improved by this method is very limited. On the other hand, thinning the insulating layer is considered to effectively reflect the force generated by the vibrator on the discharge pressure of the pump, and is an extremely effective means for increasing the discharge pressure of the pump. However, in order to ensure electrical insulation and the like of the vibrator, the insulating layer must be reliably formed, and its thickness is desirably 0.05 mm or more. As a material for forming the insulating layer, it is desirable to use an insulating polymer resin having relatively low elasticity, such as epoxy, vinyl chloride, or polyimide, rather than an elastic body such as silicon rubber. Examples of the method for forming the insulating layer include a method of applying a resin precursor (monomer or the like) to the vibrator and curing it by heat or light, or a method of attaching a resin film coated with an adhesive. Can be In the present invention, in order to obtain a piezoelectric pump having a high discharge pressure, the opening pressure (pressure at which the valve opens with a positive pressure) as a suction and discharge check valve is 0.01 kg / cm ^2.
Below, and withstand pressure (pressure at which the valve can withstand back pressure) is 1k
Another feature is to use an umbrella type valve having characteristics of g / cm ² or more. The opening pressure of the umbrella type valve is 0.01 kg /
cm ² or less is desirable. When the opening pressure exceeds 0.01 kg / cm ² , the valve cannot follow the frequency of the vibrator, and the self-priming force and discharge amount of the pump decrease. on the other hand,
The pressure resistance of the umbrella type valve is desirably 1 kg / cm ² or more. When the pressure resistance is less than 1 kg / cm ² , when the fluid is pumped to a long distance or a high position, a considerable pressure is applied to the discharge check valve of the piezoelectric pump to cause a leak, thereby lowering the discharge pressure of the pump. Would. In order to manufacture a small-sized piezoelectric pump, it is preferable that the center of the umbrella type valve is located on the diameter of the piezoelectric vibrator, and the umbrella portions of the valve overlap each other via the wall surface of the pump chamber. This is also one of the features of the present invention. As the piezoelectric material constituting the piezoelectric vibrator of the present invention, a ceramic material or an organic material can be used. Specifically, a ceramic material such as lead titanate and lead zirconate titanate is used. And polyvinylidene fluoride. More preferably, a piezoelectric plate having a dielectric constant of 3000 or more and an electromechanical coupling coefficient Kp of 50% or more is adhered to both sides of the metal plate via a metal plate in the same polarization direction, and has a diameter of 20 to 80 m.
m, the thickness of the vibrator is 1.0 to 25 mm, and the capacitance is 15
Those having characteristics of 0 to 200 nF are preferable. It is preferable that the outlet of the pump is as close as possible to the packing for fixing. Desirably, a position closest to the packing for fixing on the outer peripheral portion of the discharge port of the pump is attached within 0 to 5 mm of the inner end of the packing for fixing. When the position closest to the packing for fixing on the outer peripheral portion of the discharge port is provided at a position farther than 5 mm of the inner end of the packing for fixing, when the pump chamber is driven from an empty state, air is discharged between the discharge port and the packing for fixing. The amount of air that accumulates and accumulates as the distance from the packing increases, and it may be difficult to remove the air. Next, the present invention will be described by way of examples. Example 1 A composite oxide composed of Pb, Zr, Ti, and La was sintered and machined into a disk shape having a diameter of 50 mm and a thickness of 0.6 mm, and electrodes were baked on both surfaces thereof to perform a polarization treatment. Thus, a disk-shaped piezoelectric ceramic plate having a piezoelectric characteristic of a relative dielectric constant of 3900 and an electromechanical coupling coefficient of kp60% was produced. The two piezoelectric ceramic plates are bonded together via a phosphor bronze plate having a thickness of 0.1 mm in the same polarization direction, and a lead wire is attached so that the two piezoelectric ceramic plates are electrically parallel to each other to form a vibrator. Obtained. The obtained vibrator was placed in a 37.5 mm diameter O
As a result of examining the generated force by setting the area within a radius of 2 mm from the center of the electrode surface as a load point,
Its value was 3.0 kgf. In measuring the generated force, DC 200 V was applied to the vibrator. An epoxy resin precursor was applied to the entire surface of the vibrator and cured to form an epoxy resin insulating layer having a thickness of 0.2 mm. Next, a piezoelectric pump having the same structure as that shown in FIG. 1 was assembled using this vibrator. That is, a vibrator covered with an insulating layer was formed by removing an outer diameter of 50 mm, an inner diameter of 46 mm, and a thickness of 0.1 mm.
It was sandwiched by a flat casing made of aluminum via a fixing packing made of 3 mm silicone rubber. Here, the casing was provided with nozzles as a suction port and a discharge port, and a duckbill type check valve was attached to each of the nozzles. Example 2 A vibrator was manufactured by changing the size of the piezoelectric ceramic plate used in Example 1 to 50 mm in diameter and 1.0 mm in thickness. The generated force was measured by the same measuring method as in Example 1 and was found to be 5 kgf. An epoxy resin insulating layer having a thickness of 0.2 mm was formed on the entire surface of the vibrator in the same manner as in Example 1, and a piezoelectric pump was manufactured in the same manner as in Example 1 using this vibrator. Example 3 A silicon rubber precursor was applied to the entire surface of the same vibrator as in Example 1, and was cured to form a 0.2 mm thick silicon rubber insulating layer. Next, a piezoelectric pump was manufactured using this vibrator in the same manner as in Example 1. Example 4 An insulating layer of silicon rubber having a thickness of 0.2 mm was formed on the entire surface of the same vibrator as in Example 2 in the same manner as in Example 3. Next, a piezoelectric pump was manufactured using this vibrator in the same manner as in Example 1. Comparative Example 1 A silicon rubber precursor was applied to the entire surface of the same vibrator as in Example 1 and cured to form a 2.0 mm thick silicon rubber insulating layer. Using this, a piezoelectric pump was produced in the same manner as in Example 1. Comparative Example 2 A 2.0 mm thick silicon rubber insulating layer was formed on the entire surface of the same vibrator as in Example 2 in the same manner as in Comparative Example 1. Using this, a piezoelectric pump was produced in the same manner as in Example 1. The piezoelectric pumps obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were connected to a commercial power supply of 200 V and 50 Hz to
The maximum discharge pressure when flowing 5 ° C. water was measured. Table 1 shows the results. [Table 1] Embodiment 5 FIG. 2 shows the configuration of the piezoelectric pump used in this embodiment. As the piezoelectric vibrator, a composite oxide composed of Pb, Zr, Ti, and La was sintered and machined to obtain a dielectric constant of 3000.
Electrodes are applied to both surfaces of two piezoelectric elements having an electromechanical coupling coefficient Kp of 62%, and a lead wire for applying an AC voltage is attached to the two piezoelectric elements which are bonded together with their polarization directions interposed therebetween via a phosphor bronze plate. An epoxy resin was coated to electrically insulate the surface. The diameter of the piezoelectric vibrator is 50mm
φ and thickness (after epoxy resin application) were 1.5 mm. The casing was provided with a suction port and a discharge port, and a suction umbrella valve and a discharge umbrella valve were attached to each. In this embodiment, the opening pressure is 0.005 kg / c.
An umbrella type valve showing m ² and a pressure resistance of 1.1 kg / cm ² was used. As a communication hole connecting the pump chamber with the suction port and the discharge port, a hole having a diameter of 2 mm is formed 6 m from the center of the valve.
8 were provided at the position of m. Table 2 shows the measurement results of pump characteristics when water was flowed using the piezoelectric pump of the present invention. Note that an AC voltage of 200 V and 50 Hz was applied to the piezoelectric vibrator. Comparative Example 3 The procedure of Example 5 was repeated except that a ball valve was used instead of the umbrella-type valve of Example 5. Table 2 shows the results. Comparative Example 4 Instead of the umbrella type valve of Example 5, the opening pressure was 0.05 kg /
Except for using an umbrella-type valve having a size of cm ² , the same procedure was performed as in Example 5. Table 2 shows the results. [Table 2] Embodiment 6 FIG. 3 shows the configuration of a piezoelectric pump used in this embodiment. This piezoelectric pump is much smaller than a conventional piezoelectric pump, and is suitable for being incorporated (built-in) in medical equipment, industrial equipment, physics and chemistry equipment, and the like. As the fixing packing, silicone rubber having an outer diameter of 25 mm, an inner diameter of 21 mm, and a thickness of 300 μm is used.
b, Zr, Ti, La composite oxide sintered and machined, dielectric constant 3900, electromechanical coupling coefficient K
An electrode is applied to both sides of two piezoelectric elements having a p of 60%, and the electrodes are bonded together through a phosphor bronze plate in the same polarization direction, and a lead wire for applying an AC voltage is attached. This piezoelectric vibrator was coated with an epoxy resin to electrically insulate its surface. The diameter of the vibrator was 25 mmφ, and the thickness (after epoxy resin application) was 1.0 mm. The casing was provided with a suction port and a discharge port, and a suction umbrella valve and a discharge umbrella valve were attached to each. In this embodiment, the opening pressure is 0.005 kg /
cm ^2, using an umbrella-type valve showing the breakdown voltage 1.1 kg / cm ^2, there center of the valve are on the diameter of the piezoelectric vibrator, and a portion of the umbrella portion of each other across the partition wall of the pump chamber It was set so that it overlapped. The size of the produced piezoelectric pump is 35 mm
Despite its very small size (vertical) × 35 mm (horizontal) × 25 mm (height), the pump characteristics when water is supplied to this piezoelectric pump are as follows: discharge rate 100 ml / min, discharge pressure 0. It was 3 kg / cm ² . Note that an AC voltage of 200 V and 50 Hz was applied to the piezoelectric vibrator. According to the piezoelectric pump of the present invention, the power generated by the vibrator is transmitted to the fluid without any loss by reducing the thickness of the insulating layer of the piezoelectric vibrator. By using the vibrator which is used, a higher discharge pressure can be obtained. Also, by using an umbrella type valve as a check valve of the piezoelectric pump, the size of the piezoelectric pump can be easily reduced, and by using an umbrella type valve having specific physical properties, the valve follows the frequency of the piezoelectric vibrator. As a result, the pump efficiency can be improved, and the pump characteristics such as self-priming force, discharge amount, and discharge pressure can be increased.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing a structure of a piezoelectric pump according to the present invention. FIG. 2 is a sectional view showing the structure of the piezoelectric pump of the present invention. FIG. 3 is a sectional view showing the structure of the piezoelectric pump of the present invention. [Description of Signs] 1: Casing 2: Suction port 3: Discharge port 4: Suction check valve 5: Discharge check valve 6: Piezoelectric vibrator 7: Fixing packing 8: Insulating layer 9: Pump chamber

──────────────────────────────────────────────────続 き Continued from the front page (56) References JP-A-4-72479 (JP, A) JP-A-3-8679 (JP, U) JP-A-61-41878 (JP, U) JP-A-63 183387 (JP, U) Japanese Utility Model Showa 64-15789 (JP, U) Japanese Utility Model Application Hei 4-89871 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F04B 43/00-47 / 14 F04B 53/00-53/22

Claims (1)

(57) [Claims 1] An outer peripheral portion of a piezoelectric vibrator is sandwiched and fixed by a casing fitted with a packing corresponding to the diameter of the vibrator, and a fluid is provided on one side of the casing. In a piezoelectric pump in which a suction port and a fluid discharge port are provided, and a suction and discharge check valve is provided in each of them to form a pump chamber, the opening pressure (valve by positive pressure) is applied to the suction and discharge check valves. opening pressure), 0.01 kg / cm ² or less, and, using the umbrella valve that withstand (pressure valve in the opposite pressure withstand) has a 1 kg / cm ² or more characteristics, and the center of the umbrella valve A piezoelectric pump, which is located on the diameter of a piezoelectric vibrator, wherein the umbrella portion of the valve overlaps via the wall of the pump chamber.