KR100454487B1 - Micro-Generator with Cycling Microfluidic Circuitry - Google Patents

Abstract

The present invention relates to a closed-circuit type microgenerator in the field of industrial precision machinery, and more particularly, to the power generation principle and power generation apparatus of a microgenerator having a small size.

The microgenerator of the present invention has a microchannel having a closed circulation circuit of a microsystem, a working fluid circulating in the pupil of the microchannel through boiling and condensation due to a temperature difference, and a boiling and condensation of the working fluid. An exercise device for converting thermal energy into mechanical kinetic energy by reciprocating with a power source, a power generation element for converting mechanical kinetic energy into electrical energy by vertical reciprocating motion of the exerciser, and the working fluid does not flow backward in the microchannel pupil It consists of a backflow prevention means to prevent.

Description

Closed-Circulation Microgenerator {Micro-Generator with Cycling Microfluidic Circuitry}

The present invention relates to a closed-circuit type microgenerator in the field of industrial precision machinery, and more particularly, to the power generation principle and power generation apparatus of a microgenerator having a small size.

The present invention utilizes a given temperature difference to induce a current, and applies the thermodynamics and heat transfer for the boiling and condensation of small liquids and the microfabrication technology of MEMS (Microelectro Mechanical System) to the field of micro power generation.

The micro system, which is a micro technology, has a lot of devices that require electricity such as a micro sensor and a micro actuator, including a micro pump and a micro processor.

The voltage and current required to drive these devices is very small compared to the consumption of the macro system, but due to the limitation of the volume of micro, it has been difficult to provide a stable power supply within a limited size.

Current MEMS power supply methods include micro fuel cells, micro batteries, and microwaves.

In recent years, however, the company has begun to envision a semi-permanent self-powered system using an external environment with temperature differences instead of using an external power source. I was looking for an autonomous MEMS.

Several development methodologies have been studied for the purpose of developing a power source for such a self-driven system.

Most of these methodologies are based on phenomena discovered long ago.

The characteristics of the power generation method in a large macro system in the related art have a form in which the working fluid moves inside the equipment when there is a high temperature part and a low temperature part, passes through them sequentially, heats the high temperature part, works outside, and cools the low temperature part to circulate to the hot part. .

For example, internal combustion engines undergo air intake, heating (combustion), expansion (work), and exhaust from the outside, forming a continuous cycle with the intake of fresh air.

However, in microsystems, constraints on volume and microfabrication methods and integration with other electrical and electronic circuits must be considered.

Considering this point, there is a power generation method using a thermoelectric module as a technology having a very high applicability to MEMS microstructures.

This method uses the Seebeck Effect, in which a current is induced by joining two different metals and then giving a temperature difference between them.

This method is simple in structure and reliable, suitable for the microstructure of MEMS, and can generate electricity for various temperature differences.

In addition, there is no need for a working fluid or mechanical motion, which is advantageous in terms of safety and noise.

However, despite the ongoing development of suitable materials for improving performance, it is still insufficient to supply power for MEMS micropumps due to low efficiency and low current and voltage.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an alternative to a power generation method using a low efficiency and low voltage thermoelectric module that directly converts thermal energy into electrical energy using a semiconductor. It is intended to extend and modify the proven development concept of the macro system to the micro system.

Another object of the present invention is a closed-circuit type microgenerator capable of stably supplying power by applying the concept of a thermodynamic cycle to a microsystem so that higher efficiency and voltage can be obtained in a smaller area than the conventional microgeneration method. To provide.

In order to achieve the above object, the present invention has improved these devices in two directions: a micro reciprocating device for converting thermal energy into mechanical kinetic energy and a micro power generating device for converting mechanical kinetic energy to electrical energy.

To improve the performance of each device, technical details such as continuous operation, ease of MEMS micromachining, high efficiency and voltage generation capability, economical use even for single use, and robust structure that can withstand external shocks are taken into consideration. It was.

1 is an internal structural diagram of a micro generator according to a first embodiment of the present invention.

2 is an internal structural diagram of a micro generator according to a second embodiment of the present invention.

3A and 3B are power generation conceptual diagrams in the case of FIG. 1.

4A and 4B are power generation conceptual diagrams in the case of FIG. 2.

5A and 5B are views showing the role of the microvalve for preventing backflow in the microgenerator of the present invention.

<Description of the symbols for the main parts of the drawings>

10: magnet 12: working fluid

14 coil 16 thin film

18: heat insulation portion 20: heating portion

22 cooling part 24 micro valve (capillary pump)

26: dummy mass 28: PZT

30: microchannel

Hereinafter, the configuration and operation of the present invention will be described with reference to the accompanying drawings.

MEMS microsystems have a simple two-dimensional structure as long as it is possible to obtain long-term reliability and ease of manufacture.

To this end, the structure of the microgenerator according to the invention consists of several very simplified components.

A microchannel having a closed circulation circuit of a microsystem, a working fluid circulating in the pupil of the microchannel through boiling and condensation by temperature differences, and a reciprocating motion up and down through boiling and condensation of the working fluid Primer Mover for converting the mechanical kinetic energy into mechanical power, a power generating element for converting the mechanical kinetic energy into electrical energy by the vertical reciprocating motion of the exerciser, and the working fluid is prevented from flowing back in the microchannel pupil And backflow prevention means.

1 is an internal structural diagram of a microgenerator according to a first embodiment of the present invention.

1 shows a magnet 10 used as an exerciser for converting thermal energy into mechanical kinetic energy, and a coil 14 wound in multiple layers outside the magnet 10 as a power generating element for converting mechanical kinetic energy into electrical energy. do.

In addition, as the backflow preventing means, a capillary pump 24 for continuously supplying the working fluid 12 into the cavity of the microvalve 24 or the microchannel 30 as shown in FIG. 5 is used.

Referring to FIG. 1 in detail, the lower heating part 20 is continuously supplied with heat by conduction heat transfer from a heat source.

The microchannel 30 of the upper part of the heating unit 20 is spaced apart by a predetermined distance and arranged in a vertical zigzag to face each other and is opened and closed by the thin film 16, the magnet which can move up and down between the spaced middle of the microchannel 30 ( 10 and the coil 14 wound outside the magnet 10 is located.

A cooling unit 22 is formed between the outside of the micro channel 30 and arranged in an upper portion and zigzag, and a heat insulating unit 20 is formed between the heating unit 20 and the micro channel 30 except for a central portion. Is formed.

The heating unit 20 and the cooling unit 22 are made of a material such as copper, gold, aluminum having good heat transfer properties, and the heat insulating part 18 is made of a material having good heat insulating properties.

In the microchannel 30, the thin film 16 having the magnet 10 positioned thereon is formed, and as the temperature increases, the thin film 16 expands due to pressure, thereby causing the magnet 10 to rise upward.

In the present invention, as the thin film 16, silicon rubber is used.

A capillary pump 24 or microvalve 24 is installed in the microchannel 30 to prevent the working fluid 12 from flowing in the microchannel 30 in the reverse direction.

The development principle of this configuration is based on a thermodynamic cycle in which the working fluid 12 undergoes a phase change as it circulates through the microchannel 30 and is a latent heat, which is a heat required for the phase change during this conversion process. ) Is used for development.

Specifically, heat is continuously supplied from the heat source by conduction heat transfer to the heating unit 20, which is a heating copper plate under the generator in a state in which the microvalve 30 is closed by the thin film 16 in the first step. .

The supplied heat supplies heat to the microchannel 30 through a central portion where no thermal insulation 18 is formed, which causes the working fluid of the microchannel 30 to phase change from liquid 12 to gas. Used.

Therefore, the heating unit 20 serves as a boiler for continuously generating bubbles.

In the second step, the gaseous volume and pressure continue to rise in the closed cavity of the microchannel 30 by the bubbles.

At this time, the elevated pressure prevents the working fluid 12 from flowing in the reverse direction by compressing the microvalve 24 as shown in FIG. 5B, thereby maintaining a high pressure in the closed state.

The capillary pump 24 may be used instead of the microvalve 24 to continuously supply liquid into the cavity of the microchannel 30.

At this time, the pressure difference obtained by the capillary pump 24 should be greater than the pressure rising in the pupil.

In the third step, when the elevated pressure expands the upper thin film 16, the high pressure gas in the cavity of the microchannel 30 is pushed out by pushing the magnet 10 on the thin film 16 upward as shown in FIG. 3B.

As a result, an induced current is generated in the coil 14 wound around the magnet 10.

This action of the working fluid 12 can be seen as expansion into the low pressure condensation in the high pressure pupil and the thin film 16 and the magnet 10 act as a kind of turbine.

In the final stage, the fourth stage, the exiting gaseous working fluid 12 continues from the cooling section 22, such as a low temperature cooling copper plate and fins, on the upper and side surfaces of the microvalve 30 again. The heat is taken away to cool, condense and run off.

At this time, the magnet 10 and the thin film 16, which are the mover, are dropped by their own loads to close the microchannel 30 again.

In this way, the working fluid 12 undergoes a series of boiling, expansion, condensation, and compression processes in a closed circulation circuit to form a kind of thermodynamic cycle, in which the expansion of the working fluid 12 exits the microchannel 30. By vibrating the magnet 10 as an exerciser, the electricity is induced.

The vertical reciprocation of the magnet 10 produces electricity by inducing a current in the coil 14 fixed around the magnet 10.

2 is an internal structural diagram of a microgenerator according to a second embodiment of the present invention.

FIG. 2 is a dummy mass 26 having only mass as a prime mover for converting thermal energy into mechanical kinetic energy, and the dummy mass 26 as a power generating element for converting mechanical kinetic energy into electrical energy. A PZT 28 connected to the edge of c) is used.

In addition, as the backflow preventing means, a capillary pump 24 for continuously supplying the working fluid 12 into the cavity of the microvalve 24 or the microchannel 30 as shown in FIG. 5 is used.

2, the lower heating part 20 receives heat continuously by conducting heat transfer from a heat source.

The microchannel 30 on the heating unit 20 is arranged in a vertical zigzag spaced apart from each other by a predetermined distance, and is opened and closed by the thin film 16, and a thin film capable of vertically moving between the microchannels 30 spaced apart from each other. 16) The dummy scalpel 26 and the PZT 28 connected to the dummy scalpel 26 are positioned.

A cooling unit 22 is formed between the outside of the micro channel 30 and arranged in an upper portion and zigzag, and a heat insulating unit 20 is formed between the heating unit 20 and the micro channel 30 except for a central portion. Is formed.

The heating unit 20 and the cooling unit 22 are made of a material such as copper, gold, aluminum having good heat transfer properties, and the heat insulating part 18 is made of a material having good heat insulating properties.

In the micro channel 30, the thin film 16 having the dummy scalpel 26 positioned thereon is formed, and as the temperature increases, the thin film 16 is inflated by the rising pressure in the micro channel 30. The scalpel 28 is lifted up.

In the present invention, as the thin film 16, silicon rubber is used.

A capillary pump 24 or microvalve 24 is installed in the microchannel 30 to prevent the working fluid 12 from flowing in the microchannel 30 in the reverse direction.

As shown in FIG. 1, the principle of development of the above construction is based on a thermodynamic cycle, in which the working fluid 12 undergoes a phase change as it circulates through the microchannel 30 and is required for the phase change during the conversion process. Latent Heat, which is heat, is used for power generation.

Specifically, heat is continuously supplied from the heat source by conduction heat transfer to the heating unit 20, which is a heating copper plate under the generator in a state in which the microvalve 30 is closed by the thin film 16 in the first step. .

The supplied heat supplies heat to the microchannel 30 through a central portion where no thermal insulation 18 is formed, which causes the working fluid 12 of the microchannel 30 to change phase from liquid to gas. Used.

Therefore, the heating unit 20 serves as a boiler for continuously generating bubbles.

In the second step, the volume and pressure of the gaseous state continue to rise in the cavity of the microchannel 30 by the bubbles.

At this time, the elevated pressure prevents the working fluid 12 from flowing in the reverse direction by compressing the microvalve 24 as shown in FIG. 5B, thereby maintaining a high pressure in the closed state.

The capillary pump 24 may be used instead of the microvalve 24 to continuously supply liquid into the cavity of the microchannel 30.

At this time, the pressure difference obtained by the capillary pump 24 should be greater than the pressure rising in the pupil.

In the third step, when the elevated pressure expands the upper thin film 16, the high pressure gas in the cavity of the microchannel 30 is pushed out by pushing the dummy scalpel 26 on the thin film 16 upward as shown in FIG. 4B. Will go out.

This causes a deformation in the PZT 28 connected to the edge of the dummy scalpel 26 to induce a current in the PZT 28.

This action of the working fluid 12 can be seen as expansion into the low pressure condensation in the high pressure pupil and the thin film 16 and the dummy scalpel 26 act as a kind of turbine.

In the final stage, the fourth stage, the exiting gaseous working fluid 12 continues from the cooling section 22, such as a low temperature cooling copper plate and fins, on the upper and side surfaces of the microvalve 30 again. The heat is taken away to cool, condense and run off.

At this time, the microchannel 30 is closed again by the spring action.

In this way, the working fluid 12 undergoes a series of boiling, expansion, condensation and compression processes in a closed circuit, forming a kind of thermodynamic cycle, in which the expansion of the working fluid 12 exits the microchannel 30. By vibrating the dummy scalpel 26 which is an exerciser, electricity is induced.

Vertical reciprocation of the dummy scalpel 26 results in displacement of the PZT 28 connected to the edge of the dummy scalpel 26 to produce electricity.

In order to rearrange the power generation process by the structure of FIGS. 1 and 2, the working fluid 12 causes a phase change due to a temperature difference (thermal energy), and this phase change causes the mechanical motion of the thin film and the moving body (magnet or dummy scalp) up and down. After converting it to energy, it is generated again by using a generator (coil, PZT) to generate induced current (electrical energy).

As described above, the present invention utilizes the phase change of the working fluid 12, so that the heat of vaporization / liquefaction generates a large volume change during the liquid-to-gas or gas-to-liquid state change of the working fluid 12. It has the advantage of generating and converting the volume change of the expansion and contraction into effective power by converting the kinetic energy of the thin film and the exerciser.

In addition, even if the temperature difference is outside the design range, efficiency and power are reduced, but some amount of electricity can be produced continuously.

Through the present invention as described above, the micro-generator according to the present invention can be used for the recovery of waste heat of power plants, chemical plants, incinerators, etc., produced in a smaller size, body temperature, solar heat, etc. as an energy source PDA, It can be used as a main power supply or auxiliary power supply for notebook computers and DNA chips.

Claims (9)

A micro channel having a closed circuit of the micro system, A working fluid circulating in the pupil of the microchannel through boiling and condensation due to temperature differences, An exerciser for converting thermal energy into mechanical kinetic energy by reciprocating up and down through boiling and condensation of the working fluid, A power generation element for converting mechanical kinetic energy into electrical energy by vertical reciprocating motion of the motor; Backflow preventing means for preventing the working fluid from flowing back within the cavity of the microchannel, Containing closed circulation fine generator. The closed generator of claim 1, wherein the working fluid is boiled and condensed by a heating part located under the microchannel and a cooling part located on the top and the side. The method of claim 1, wherein the micro-channel is closed by a thin film located below the mover, closed loop micro-generator, characterized in that the membrane is expanded and opened by the boiling of the working fluid. The closed loop fine generator according to claim 1 or 3, wherein the mover is a magnet. The method of claim 4, wherein the power generating element is a closed loop type micro-generator, characterized in that the coil wound in multiple layers on the magnet. The closed generator of claim 1 or 3, wherein the mover is simply a dummy mass having only mass. The method of claim 6, wherein the generator is a closed loop fine generator, characterized in that the PZT connected to the edge of the dummy scalpel. The closed type microgenerator of claim 1, wherein the backflow preventing means is a microvalve installed in a microchannel in which boiling occurs. The closed type microgenerator of claim 1, wherein the backflow preventing means is a capillary pump for supplying a working fluid to the microchannel in which boiling occurs.