JPH09280203A - Piezoelectric actuator for droplet radiator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device which is free from any loss in converting the expansion/ contraction of a piezoelectric element into the vibration in the thickness direction, and in which the dripping condition is not disturbed by the differential pressure between an emitter and a pressure chamber. SOLUTION: The pressure fluctuation in an emitter 11 can be directly generated by the expansion/contraction of a piezoelectric element 1 to efficiently emit the drip 17 by providing an emitter 11 which is provided with an orifice plate 15 on a lower part and whose inside is hollow, a case 3 which is arranged on an upper part in the emitter 11 and provided with a downward recessed part, a clamp member 2 arranged at a lower end of the case 3, and the flat-plate shaped piezoelectric element 1 whose end part is held between two seal sliding members 2b of the clamp member 2 to form a pressure chamber in the recessed part of the case 3, and which is expanded/ contracted by a driving power source 10. Since an air intake flow rate regulating valve provided on an intake pipe to be communicated with the pressure chamber, and a control device to control the air intake flow rate regulating valve are provided, the pressure in the pressure chamber is adjusted so as to be always equal to the pressure in the emitter, and expansion/contraction of the piezoelectric element becomes smooth to enable excellent emission of the drip.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a droplet radiator piezoelectric actuator applied to a heat dissipation system of a space station.

[0002]

2. Description of the Related Art A piezoelectric actuator for a droplet radiator that is applied to a conventional heat dissipation system of a space station and forms a minute flow rate pump has been published in the literature (Journal of the Aerospace Society, Vol. 39, No. 453, page 552). Figure 4
There was one shown in (a).

The conventional apparatus shown in FIG. 4 (a) has a suction pipe 33 connected to the upper part and an orifice plate 3 provided in the lower part.
4, a case 35 provided inside the emitter 32 and provided with a pressure chamber 36 therein, and an inside of the emitter 32 provided under the case 35 and the pressure chamber 3
It was formed by the disk-type piezoelectric element 31 partitioning between the six.

In the above, the disk-type piezoelectric element 31 generates an expansion / contraction force in the radial direction when an alternating voltage is applied,
Since the circumferential portion is fixed, the vibration having the maximum amplitude is generated at the center thereof as shown in FIG. 4 (b).

When the piezoelectric element 31 vibrates, a pressure variation occurs inside the emitter 32, and when a driving condition satisfies a certain condition, it passes from the suction pipe 33 into the emitter 32 and passes through an orifice provided in an orifice plate 34. The fluid to
The droplets are discharged from the orifice.

[0006]

In the conventional piezoelectric actuator for a droplet radiator, as described above, the expansion and contraction of the disk-shaped piezoelectric element due to the application of the alternating voltage is converted into the vibration having the maximum amplitude at the center of the piezoelectric actuator. There was a loss for this conversion as it generated internal pressure fluctuations.

Further, since there is no means for adjusting the pressure in the pressure chamber, the difference between the pressure in the emitter and the pressure in the pressure chamber, which occurs when the piezoelectric element is driven, acts on the piezoelectric element, and the piezoelectric element produces a differential pressure. Since the piezoelectric elements are operated against each other, the deformation of the piezoelectric element is absorbed by the elastic deformation due to the differential pressure, and the pressure fluctuation inside the emitter becomes small, which may make it impossible to generate droplets.

Further, as a result of these, there is a problem that the driving range of the actuator that satisfies the droplet generation condition of the droplet radiator is restricted. The present invention seeks to solve the above problems.

[0009]

[Means for Solving the Problems]

(1) In the piezoelectric actuator for a droplet radiator according to the first aspect of the invention, the inflow pipe is connected to the upper part, the orifice plate is provided in the lower part, the inside is a hollow emitter, and the inside is arranged in the upper part of the emitter and faces downward. Having a concave portion, a clamp plate fixed to the lower end of the case, a clamp member formed by two seal sliding members arranged between the clamp plate and the lower end of the case, and the clamp member And a plate-shaped piezoelectric element whose end is sandwiched between the two seal sliding members to form a pressure chamber in the recess of the case and which expands and contracts when an alternating voltage is applied from the driving power source. It has a feature.

In the above, when an alternating voltage is applied from the drive power source to the flat piezoelectric element, the piezoelectric element expands and contracts, and the volume of the portion of the piezoelectric element protruding from the seal sliding member increases or decreases, and the pressure chamber and the emitter The volume is changed, the pressure inside each is changed, and the emitter sucks the fluid from the inflow pipe and discharges it as droplets from the orifice plate.

In the present invention, since the pressure fluctuation in the emitter is directly generated by the expansion and contraction of the piezoelectric element, it is possible to avoid the loss caused by converting the expansion and contraction of the piezoelectric element in the conventional device into the vibration in the thickness direction. Becomes

(2) According to a second aspect of the invention, in the piezoelectric actuator for a liquid drop radiator according to the first aspect of the invention, the exhaust pipe is provided which penetrates the emitter and the case and communicates with a recess of the case. An exhaust valve, an intake flow rate adjusting valve provided in an intake pipe penetrating the emitter and the case to communicate with a recess of the case, and a first provided in the emitter.
Pressure gauge, a second pressure gauge provided in the pressure chamber, and a control device for inputting a pressure signal from the first and second pressure gauges to control the intake flow rate adjusting valve. There is.

In the present invention, when the piezoelectric element expands and contracts and the pressures in the pressure chamber and the emitter fluctuate, the pressure fluctuations are measured by the first and second pressure gauges and input to the control device. The intake flow rate control valve is controlled so that the pressure in the pressure chamber becomes equal to the pressure in the emitter.

Therefore, the frictional force at the contact portion of the piezoelectric element with the seal sliding member is reduced, the expansion and contraction of the piezoelectric element becomes smoother than that of the above-mentioned invention (1), and a better droplet can be discharged. Become.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A piezoelectric actuator for a droplet radiator according to a first embodiment of the present invention will be described with reference to FIG.

In the piezoelectric actuator according to this embodiment shown in FIG. 1, the inflow pipe 14 is connected to the upper portion and the orifice 16 is provided.
A cylindrical shape having an orifice plate 15 having a lower part and a hollow inside, and a downward recess communicating with the intake pipe 5 passing through the emitter 11 and the exhaust pipe 6 disposed in the upper part of the emitter 11. Case 3, same case 3
A ring plate-shaped clamp plate 2a provided at the lower end of the ring, two ring-shaped rubber members 2b, and a plurality of tightening bolts 2c
The driving power source 10 has an end portion sandwiched between the clamp member 2 and two rubber members 2b of the clamp member 2
And a disk-shaped piezoelectric element 1 for forming a pressure chamber 4 in the concave portion of the case 3 connected to.

The exhaust pipe 6 is provided with an exhaust valve 9, and the intake pipe 5 is provided with an intake valve 7 and a check valve 8. The check valve 8 provided in the intake pipe 5 is provided to prevent the backflow of the fluid in the pressure chamber 4, and is attached to the tip of the intake pipe 5 in FIG. 1, but is not the tip. Good.

The rubber member 2b seals the piezoelectric element 1 and slides the piezoelectric element 1 when the piezoelectric element 1 expands and contracts, and is a seal sliding member for the piezoelectric element 1.

Next, the driving procedure of the piezoelectric actuator according to this embodiment will be described. In driving this piezoelectric actuator, first, the pressure chamber 4 is set to an appropriate pressure so that the fluctuating pressure difference between the pressure chamber 4 and the emitter 11 is minimized. Closes the exhaust valve 9 and opens the intake valve 7, and closes the intake valve 7 and opens the exhaust valve 9 when lowering.

After the pressure in the pressure chamber 4 reaches an appropriate pressure, both the intake valve 7 and the exhaust valve 9 are closed,
The alternating voltage supplied from the driving power supply 10 is applied to the piezoelectric element 1. This alternating voltage is shown in FIG.

When an alternating voltage is applied to the piezoelectric element 1, the piezoelectric element 1 is gently moved to the case 3 by the rubber member 2b.
2B, the rubber member 2b expands and contracts in the radial direction to increase or decrease the volume inside the pressure chamber 4 and the inside of the emitter 11 as shown in FIG. 2 is changed as shown in FIG.

Therefore, the fluid passing from the inflow pipe 14 through the inside of the emitter 11 and the orifice 16 provided in the orifice plate 15 is discharged as droplets 17 to the outside of the emitter 11.

In this embodiment, the expansion and contraction of the piezoelectric element 1 directly causes the pressure fluctuation in the emitter 11.
Since it is not necessary to change the direction of force such as the expansion and contraction of the piezoelectric element 1 to vibrate in the thickness direction as in the conventional device, it is possible to avoid the loss for that.

Since the pressure in the pressure chamber 4 is adjusted in advance by the intake valve 7 and the exhaust valve 9 so that the pressure difference between the pressure in the emitter 11 and the pressure in the emitter 11 is minimized, the fluid in the emitter 11 is pressurized. The tightening force of the rubber member 2b for sealing so as not to enter the chamber 4 is small, and the frictional force acting on the piezoelectric element 1 from the rubber member 2b is small. as a result,
The piezoelectric element 1 expands and contracts smoothly, and is effectively used for droplet generation.

A piezoelectric actuator for a droplet radiator according to the second embodiment of the present invention will be described with reference to FIG. In the piezoelectric actuator according to the present embodiment shown in FIG. 3, an intake flow rate adjusting valve 7a is used instead of the intake valve 7 in the first embodiment, and a pressure gauge 12a capable of measuring the internal pressures of the emitter 11 and the pressure chamber 10 is used. , 12b are provided, and a pressure signal is input from the pressure gauges 12a, 12b to control opening / closing of the intake flow rate adjusting valve 7a.
3 is provided.

In the present embodiment, the pressure inside the emitter 11 and the pressure inside the pressure chamber 10 are always the pressure gauge 12 respectively.
a, 12b, and pressure gauges 12a, 12
The pressure signal measured by b is input to the control device 13, and the control device 13 controls the intake flow rate adjusting valve 7a so that the pressure in the pressure chamber 10 is always equal to the pressure in the emitter 11.

Therefore, a force in the plate thickness direction due to a pressure difference between the pressure chamber 4 and the emitter 11 does not act on the piezoelectric element 1,
In the portion of the piezoelectric element 1 clamped by the rubber member 2b, the frictional force when the piezoelectric element 1 expands and contracts is further reduced as compared with the case of the first embodiment, and the expansion and contraction of the piezoelectric element 1 becomes smoother.

[0028]

The piezoelectric actuator for a liquid drop radiator according to the present invention has an orifice plate provided in the lower part, a hollow emitter, and a case having a downward recessed part disposed in the upper part of the emitter, and a case of the same. A flat plate-shaped piezoelectric element which is sandwiched between a clamp member arranged at the lower end and two seal sliding members of the same member to form a pressure chamber in the recess of the case and which expands and contracts by a drive power source. By providing the element, the pressure fluctuation in the emitter can be directly generated by the expansion and contraction of the piezoelectric element, so that the droplets can be efficiently discharged, and the intake pipe connected to the pressure chamber is provided. Since the intake flow rate control valve and the control device that controls the intake flow rate control valve by inputting the pressures in the pressure chamber and the emitter are installed, the pressure in the pressure chamber is adjusted to be always equal to the pressure in the emitter. Since the expansion and contraction of the piezoelectric element becomes smooth, it becomes possible to release a good droplet.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a piezoelectric actuator for a droplet radiator according to a first embodiment of the present invention.

FIG. 2 is an operation explanatory view of the piezoelectric actuator according to the first embodiment, in which (a) is a voltage applied to the piezoelectric element,
(B) is expansion and contraction of a piezoelectric element, (c) is explanatory drawing of the pressure fluctuation in a pressure chamber and an emitter.

FIG. 3 is an explanatory diagram of a droplet radiator piezoelectric actuator according to a second embodiment of the present invention.

FIG. 4 is an explanatory view of a conventional device, in which (a) is a configuration of the device,
(B) is an explanatory view of the operation of the device.

[Explanation of symbols]

 1 Piezoelectric element 2 Clamp member 2a Clamp plate 2b Rubber member 2c Tightening bolt 3 Case 4 Pressure chamber 5 Intake pipe 6 Exhaust pipe 7 Intake valve 7a Intake flow control valve 8 Check valve 9 Exhaust valve 10 Drive power supply 11 Emitter 12a, 12b Pressure Total 13 Control device 14 Inflow pipe 15 Orifice plate 16 Orifice 17 Droplet

Claims (2)

[Claims] 1. An inflow pipe is connected to an upper part, an orifice plate is provided in a lower part, a hollow emitter, a case having a downward recessed part disposed in the upper part of the emitter, and a clamp fixed to a lower end of the case. Plate and a clamp member formed by the clamp plate and the two seal sliding members disposed between the lower end of the case and the case, and an end portion of the clamp member between the two seal sliding members of the clamp member. A piezoelectric actuator for a droplet radiator, comprising a flat plate-shaped piezoelectric element which is sandwiched to form a pressure chamber in a recess of the case and which expands and contracts when an alternating voltage is applied from a driving power source. 2. The piezoelectric actuator for a droplet radiator according to claim 1, wherein an exhaust valve provided in an exhaust pipe penetrating the emitter and the case and communicating with a recess of the case, and penetrating the emitter and the case. An intake flow rate control valve provided in an intake pipe communicating with the recess of the case, a first pressure gauge provided in the emitter, a second pressure gauge provided in the pressure chamber, and the first and second A piezoelectric actuator for a droplet radiator, comprising a control device for controlling a suction flow control valve by inputting a pressure signal from a pressure gauge.