WO2016194700A1 - Cooling device - Google Patents

Abstract

The present invention relates to a cooling device that comprises: an ECE element comprising a pair of electrodes and a conductive body that is positioned between the pair of electrodes and that is configured from a material having an electrocalorimetric effect; and a cooling member positioned above the ECE element.

Description

Cooling device

The present invention relates to a cooling device.

In various electronic devices, a heat management system for controlling heat generated from various electronic components is used. As such a heat management system, for example, a relatively small electronic device uses a heat sink, a heat pipe, a thermal sheet, a heat storage material, etc., and a large electronic device uses an air conditioner such as an air conditioner, or a Peltier cooling device. A cooling fan or the like is used. However, in a small electronic device, cooling using heat radiation as described above is limited because the area of the housing is limited. In addition, a large electronic device can obtain a sufficient cooling effect by the above air conditioning equipment or the like, but has a problem that it requires a power cost for heat management because the power consumption is very large.

As a power-saving heat management system, attention has been paid to a material using an electrocaloric effect (hereinafter also referred to as “EC effect”). For example, in Non-Patent Document 1, ceramics exhibiting an EC effect are stacked with a space through which a fluid passes, and by applying and removing an electric field, ceramics absorb and generate heat, and at the same time, the fluid is moved by a pump. Thus, an apparatus is described in which heat is transferred from a hot spot to a cold spot to cool. Patent Document 1 describes a cooling device including a refrigerant unit having a ferroelectric polymer film that exhibits an EC effect. The ferroelectric polymer film is suspended between the heat sink and the heat source. By controlling the application of voltage, the ferroelectric polymer film is cooled by alternately applying a bias to the heat sink and the heat source.

US Patent Application Publication No. 2010/0175392

APPLIED PHYSICS LETTERS 106, 043903 (2015)

In Patent Document 1 and Non-Patent Document 1, it is necessary to induce heat absorption and heat generation of a material that exhibits the EC effect and at the same time, transport heat to the cold spot side through the material that exhibits the EC effect. For this reason, a fluid is supplied by a pump or a heat switch is used to transfer heat, or an element having an EC effect is moved to transfer heat, which requires a complicated device. In addition, since such a device becomes huge, it is difficult to apply it to a heat generation problem such as a small portable device or a server with limited space.

Therefore, an object of the present invention is to provide a cooling device that is simple, small and capable of performing efficient cooling.

The present inventors pay attention to an element made of the material having the above-mentioned electrocaloric effect (hereinafter also referred to as “ECE element”), and separately from a thermal contact portion (that is, a hot spot) contacting the heat source on the element. It was found that by providing a cold spot, the heat generated by the heat source can be efficiently conveyed to the cold spot.

According to a first aspect of the present invention, an ECE element comprising a pair of electrodes and a dielectric portion made of a material exhibiting an electrocaloric effect located between the pair of electrodes;
A cooling device is provided having a cooling member located on the ECE element.

According to the second aspect of the present invention, an electronic component having the above cooling device is provided.

According to the third aspect of the present invention, there is provided an electronic apparatus having the cooling device or the electronic component.

According to a fourth aspect of the present invention, there is provided a heat source using an ECE element including a pair of electrodes and a dielectric portion made of a material exhibiting an electrocaloric effect located between the pair of electrodes. A cooling method,
A part of the ECE element is brought into contact with a heat source directly or through a heat conducting member;
In the ECE element, a temperature gradient is generated between the contact portion with the heat source and another portion,
In the above state, by applying a voltage to the electrode, the dielectric part generates heat,
There is provided a cooling method including causing the dielectric portion to absorb heat by stopping application of voltage to the electrode.

According to the present invention, a simple, small, and efficient cooling device can be provided by providing a cold spot on an element that exhibits the EC effect.

FIG. 1 is a schematic cross-sectional view of a cooling device 1a according to the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a state where the cooling device 1a of FIG. 1 is installed on a heat source. FIG. 3 is a schematic cross-sectional view of a cooling device 1b according to the second embodiment of the present invention. FIG. 4 is a schematic cross-sectional view showing a state where a cooling device obtained by modifying the cooling device 1b in the second embodiment is installed on a heat source. FIG. 5 is a schematic cross-sectional view of a cooling device 1c according to the third embodiment of the present invention.

Hereinafter, the cooling device of the present invention will be described in detail with reference to the drawings. However, the shape and arrangement of the cooling device and each component of the present embodiment are not limited to the illustrated example.

As shown in FIG. 1, the cooling device 1a according to the first embodiment of the present invention includes a pair of electrodes 2 and 4 and a dielectric composed of a material that exhibits an electrocaloric effect located between the pair of electrodes. The ECE element 8 having the portion 6 and the cooling member 10 positioned on one surface of the ECE element 8 are provided. As shown in FIG. 2, the cooling device 1 a is installed so that the surface facing the surface on which the cooling member 10 is located (that is, the surface on which the electrode 4 exists) is in contact with the heat source H. By installing in this way, the temperature is high on the electrode 4 side and the temperature is low on the electrode 2 side, and a temperature gradient can be formed in the ECE element 8. When a voltage is applied between the electrodes 2 and 4, an electric field is applied to the dielectric part 6, and the dielectric part 6 generates heat. The generated heat moves to the cooling member 10 having a lower temperature (that is, a cold spot). Further, when the application of the voltage between the electrodes 2 and 4 is suspended, the electric field applied to the dielectric part 6 disappears and the dielectric part 6 absorbs heat. The endotherm is preferentially absorbed from the heat source H side (ie, the hot spot) where the heat is more abundant. That is, when heat is generated, the heat moves so as to be pushed out to the cold spot, and when the heat is absorbed, heat at the hot spot is preferentially removed. Further, since the heat transferred to the cold spot is absorbed by the cooling member 10 and heat is supplied from the heat source H to the hot spot, the ECE element 8 always has a temperature gradient. By applying voltage in a pulse manner, the ECE element 8 repeats heat generation and heat absorption, and conveys heat from the hot spot to the cold spot. In other words, the ECE element 8 functions as a heat pump.

The material showing the electrocaloric effect constituting the dielectric part 6 is not particularly limited, but BaTiO ₃ , Ba (Ti, Zr) O ₃ , Ba (Ti, Sn) O ₃ , (Ba, Sr) TiO ₃ , (1-x) Pb (Mg _1/3 Nb _2/3 ) O ₃ -xPbTiO ₃ , (1-x) Pb (Mg _1/3 Nb _2/3 ) O ₃ -xATiO ₃ (where A is (1-x) Pb (Ni _1/3 Nb _2/3 ) O ₃ -xPbTiO ₃ , (1-x) Pb (Ni _1/3 Nb), which is at least one selected from Ba, Sr and Ca. _2/3 ) O ₃ -xATiO ₃ (wherein A is at least one selected from Ba, Sr and Ca), Pb (Sc, Ta) O ₃ , (Pb, Ba) ZrO _3, etc. Ceramic materials, PVDF (polyvinylidene fluoride), etc. An organic piezoelectric body or a combination thereof can be used. The material to be used can be selected according to the equipment in which the cooling device of the present invention is installed. For example, when the cooling device is to be operated at 120 ° C., the BaTiO ₃ having a dielectric part transition temperature of around 120 ° C. Are suitable, and when it is desired to operate at 80 ° C., Ba (Ti, Zr) O ₃ , Ba (Ti, Si, to which Sr, Zr, and Sn are added as shifters so that the transition temperature is close to 80 ° C. Sn) O ₃ or (Ba, Sr) TiO ₃ or (Pb, Ba) ZrO ₃ is suitable. When used at a lower temperature, (1-x) Pb (Mg _1/3 Nb _2/3 ) O ₃ -xPbTiO ₃ or Pb (Sc, Ta) O ₃ is preferred. Further, in order to suppress the influence of the leakage current when a high voltage is applied, Mn serving as an acceptor, Ta, Nb serving as a donor, rare earth atoms, or the like may be added as appropriate. In particular, the addition of Mn is effective for Ti-based oxides, and the addition of Ta and Nb is effective for Zr-based oxides.

In the dielectric portion 6, the content of the material exhibiting the electrocaloric effect is 50% by mass or more, preferably 60% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and even more preferably. It may be 98% by mass or more, for example, 98.0 to 99.8% by mass. The dielectric portion 6 may be made of a material that substantially exhibits an electrocaloric effect.

The shape of the dielectric portion 6 is not particularly limited, and can be formed into, for example, a sheet shape, a block shape, and other various shapes. The molding method is not particularly limited, and compression, sintering, or the like can be used. Moreover, you may mix and shape | mold with binders, such as resin or glass.

The material constituting the electrodes 2 and 4 is not particularly limited, and examples thereof include Ag, Cu, Pt, Ni, Al, Pd, Au, and alloys thereof (for example, Ag—Pd). Among these, Pt, Ag, Pd, or Ag—Pd is preferable.

Since the electrodes 2 and 4 can intervene in heat transfer between the dielectric part and the heat source or between the dielectric part and the cooling member, the material constituting the electrode has high thermal conductivity from the viewpoint of heat transfer. A material such as Ag is preferred.

The shape of the electrodes 2 and 4 is not particularly limited, but preferably a shape that covers the entire surface of the dielectric portion 6 is preferable.

The cooling member 10 is not particularly limited as long as it can efficiently receive heat from the ECE element 8. For example, as the cooling member 10, a heat storage material, a member formed from a material having high thermal conductivity, or a combination thereof can be used.

The heat storage material is not particularly limited, VO _2, or VO ₂ in W, Mo, Nb, Ti, Ta, Cr, those were dissolved with Al, or, LiVO _2, or LiVO ₂ to Fe, Mn, Examples include Co, Ti added, metal halides, metal nitrates, metal carbonates, metal hydrates, paraffins, fatty acids and the like. A heat storage material can be selected according to the apparatus which installs the cooling device of this invention, and may use 1 type or in combination of 2 or more types.

For example, when used in electronic equipment, the following vanadium oxide is preferred:
V and M (wherein M is at least one selected from W, Ta, Mo and Nb), and the molar content of M is 0 mole part when the total of V and M is 100 mole parts Vanadium oxide which is not less than 5 mol parts;
Vanadium oxide containing A (where A is Li or Na) and V, and the content mole part of A when V is 100 mole parts is 50 mole parts or more and 100 mole parts or less;
When Ti or another atom selected from the group consisting of W, Ta, Mo and Nb is doped and the other atom is W, for a total of 100 mole parts of V, Ti and other atoms, When the content mole part of other atoms is larger than 0 mole part and 5 mole parts or less, and the other atom is Ta, Mo or Nb, with respect to a total of 100 mole parts of V, Ti and other atoms, The mole part of other atoms is larger than 0 mole part and 15 mole parts or less, and the mole part of titanium is 2 mole parts or more and 30 moles with respect to 100 mole parts in total of V, Ti and other atoms. Vanadium oxide which is less than or equal to parts;
V, Li, and transition metals (eg, W, Ta, Mo or Nb), the molar ratio of V to other atoms is in the range of 995: 5 to 850: 150, and the sum of V and other atoms Vanadium oxide in which the molar ratio of Li to Li is in the range of 100: 70-110;
Formula: V _1-x M _x O ₂
[Wherein M is W, Ta, Mo or Nb, and x is 0 or more and 0.05 or less]
Vanadium oxide represented by:
Formula: A _y VO ₂
[In the formula, A is Li or Na, and y is 0.5 or more and 1.0 or less]
Vanadium oxide represented by:
_{Formula: V 1-x-y Ti} x M y O 2
[Wherein M is W, Ta, Mo or Nb;
x is 0.02 or more and 0.3 or less,
y is 0 or more,
When M is W, y is 0.05 or less,
When M is Ta, Mo or Nb, y is 0.15 or less]
Vanadium oxide represented by:
Formula: Li _x V _{1- y My} O ₂
[Wherein M is a transition metal;
y and x satisfy either (a) or (b) below:
(A) y = 0 and 0.70 ≦ x ≦ 0.98, or (b) 0.005 ≦ y ≦ 0.15 and 0.70 ≦ x ≦ 1.1]
Vanadium oxide represented by

The halide of the metal is not particularly limited, for example, lithium fluoride (LiF), lithium chloride (LiCl), sodium fluoride (NaF), include magnesium fluoride (MgF ₂₎ or the like.

The nitrate of the metal is not particularly limited, for example, lithium nitrate (LiNO3), sodium nitrate (NaNO _3), potassium nitrate (KNO _3), and the like.

As carbonate of the metal is not particularly limited, for example, lithium carbonate _(Li 2 _CO 3), and the like potassium carbonate _(K 2 CO ₃₎ is.

As hydrated salt of a metal is not particularly limited, for _{example, NaCH 3 COO · 3H 2 O} , Ba (OH) 2 · 8H 2 O, Sr (OH) 2 · 8H 2 O , and the like.

Paraffins are not particularly limited, and examples thereof include n-docosane (C ₂₂ H ₄₆ ), n-tetracosane (C ₂₄ H ₅₀ ), and n-triacontane (C ₃₀ H ₆₂ ).

The fatty acid is not particularly limited, and examples thereof include stearic acid, polymitic acid, myristic acid and the like.

The member formed from a material having a high thermal conductivity is not particularly limited, and examples thereof include a heat sink, a thermal sheet, and other members formed by molding a material having a high thermal conductivity into a specific shape. The shape of the member formed from a material having high thermal conductivity is not particularly limited, and may be a sheet shape, a block shape, an uneven shape, or the like.

The material having high thermal conductivity is not particularly limited. For example, metal (for example, tin, nickel, copper, bismuth, silver, iron and aluminum, or an alloy containing them), resin (for example, Teflon, polyimide, silicone) , Graphite, carbon, or a composite in which they are combined.

The member formed from a material having high thermal conductivity can be, for example, a heat sink, a thermal sheet, a housing, or the like.

In the embodiment shown in FIG. 1, the cooling member 10 is on a plate, and the size of the contact surface with the electrode 2 and the size of the contact surface of the electrode 2 are the same. It may have the shape and size. For example, the cooling member 10 may be formed in a sheet shape so as to extend from the end of the ECE element 8. Further, the cooling member 10 may be provided with unevenness. Thus, by setting it as a sheet form or uneven | corrugated shape, the surface area of the cooling member 10 becomes large, and the thermal radiation effect improves. When the heat dissipation effect is improved, the temperature of the cold spot of the ECE element 8 is lowered and the temperature difference from the hot spot is further increased, so that the heat pump function of the ECE element 8 is improved.

The connection between the electrodes 2 and 4, the dielectric portion 6 and the cooling member 10 can be performed using, for example, an adhesive, paste, solder, brazing, or the like. Preferably, a material having high thermal conductivity, for example, a high thermal conductivity paste or solder is used. Moreover, you may connect mechanically using a screw, a pin, a nail | claw, etc.

The cooling device according to the first embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and various modifications can be made.

For example, a cooling device 1b in the second embodiment of the present invention is shown in FIG. The cooling device 1b includes a heat conducting member 12 on the electrode 4 in addition to the structure of the cooling device 1a. The cooling device 1b is installed such that the heat conducting member 12 contacts the heat source.

Although the material which comprises the heat conductive member 12 is not specifically limited, It may be mentioned as a material with said high heat conductivity.

In FIG. 3, the heat conducting member 12 is on a plate, and the size of the contact surface with the electrode 2 and the size of the contact surface of the electrode 4 are the same, but not limited to this, various shapes and You may have a size. For example, as shown in FIG. 4, the heat conducting member 12 may extend from the end of the ECE element 8. With such a configuration, the heat source existing at a distant place and the ECE element 8 can be thermally coupled. In FIG. 4, the ECE element 8 is located on one main surface of the heat conducting member 12 and the heat source H exists on the opposite surface, but the ECE element 8 and the heat source H are on the same face of the heat conducting member 12. May be present.

FIG. 5 shows a cooling device 1c according to the third embodiment of the present invention. In the cooling device 1c according to the third embodiment of the present invention, a plurality of internal electrodes 14a and 14b and a plurality of dielectric portions 16 are alternately stacked. The internal electrodes 14a and 14b are electrically connected to external electrodes 20a and 20b disposed on the end face of the ECE element 18, respectively. When a voltage is applied from the external electrodes 20a and 20b, an electric field is formed between the internal electrodes 14a and 14b. Due to this electric field, the dielectric portion 16 generates heat. When the voltage is removed, the electric field disappears, and as a result, the dielectric portion 16 absorbs heat. The cooling member 10 is disposed on the upper surface of the ECE element 18.

By adopting such a structure, it becomes possible to apply a strong electric field to the dielectric portion 16, and the temperature difference (ΔT) between application of voltage and rest time can be further increased.

As described above, the ECE element can function as a heat pump by forming a hot spot and a cold spot and giving a temperature gradient to the ECE element. By using this function, efficient cooling becomes possible.

Accordingly, the present invention is a method of cooling a heat source using an ECE element comprising a pair of electrodes and a dielectric portion made of a material exhibiting an electrocaloric effect located between the pair of electrodes. ,
A part of the ECE element is brought into contact with a heat source directly or through a heat conducting member;
In the ECE element, a temperature gradient is generated between the contact portion with the heat source and another portion,
In the above state, by applying a voltage to the electrode, the dielectric part generates heat,
Provided is a cooling method including causing a dielectric part to absorb heat by stopping application of a voltage to the electrode.

In the present invention, it is only necessary that the dielectric part absorbs and generates heat when voltage is applied and stops. The dielectric part generates heat when applied and may absorb heat when stopped, or absorbs heat when applied and stops when stopped. It may generate heat.

In the above cooling method, it is preferable to use the ECE element 18 in the third embodiment as the ECE element to be used.

In the above cooling method, it is preferable to use the above-described cooling device of the present invention.

The present invention also provides an electronic component having the cooling device of the present invention and an electronic apparatus having the cooling device or the electronic component.

Although it does not specifically limit as an electronic component, For example, a central processing unit (CPU), a hard disk (HDD), a power management IC (PMIC), a power amplifier (PA), a transceiver IC, a voltage regulator (VR), etc. Light emitting elements such as integrated circuits (ICs), light emitting diodes (LEDs), incandescent bulbs, semiconductor lasers, parts that can be heat sources such as field effect transistors (FETs), and other parts such as lithium ion batteries, substrates, heat sinks And parts commonly used in electronic devices such as housings.

The electronic device is not particularly limited, and examples thereof include a mobile phone, a smartphone, a personal computer (PC), a tablet terminal, a hard disk drive, and a data server.

The cooling device of the present invention can be used as a cooling device for various devices, for example, electronic devices in which the heat countermeasure problem has become prominent.

DESCRIPTION OF SYMBOLS 1a, 1b, 1c ... Cooling device 2, 4 ... Electrode 6 ... Dielectric part 8 ... ECE element 10 ... Cooling member 12 ... Heat conduction member 14a, 14b ... Internal electrode 16 ... Dielectric part 18 ... ECE element 20a, 20b ... External electrode

Claims (15)

An ECE element comprising a pair of electrodes and a dielectric portion made of a material exhibiting an electrocaloric effect located between the pair of electrodes;
A cooling device comprising a cooling member located on the ECE element. The cooling device according to claim 1, further comprising a heat conducting member that contacts at least a part of the ECE element. The cooling device according to claim 2, further comprising a cooling member on one surface of the ECE element and a heat conducting member on a surface facing the cooling member. The cooling device according to any one of claims 1 to 3, wherein the electrode is made of Pt, Ag, Pd, or Ag-Pd. 5. The cooling device according to claim 1, wherein a plurality of electrodes and a plurality of dielectric portions are alternately laminated. The material that shows the electrocaloric effect constituting the dielectric part is BaTiO ₃ , Ba (Ti, Zr) O ₃ , Ba (Ti, Sn) O ₃ , (Ba, Sr) TiO ₃ , (1-x) Pb ( Mg _1/3 Nb _2/3 ) O ₃ —xPbTiO ₃ , (1-x) Pb (Mg _1/3 Nb _2/3 ) O ₃ —xATiO ₃ (wherein A is selected from Ba, Sr and Ca) (1-x) Pb (Ni _1/3 Nb _2/3 ) O ₃ -xPbTiO ₃ , (1-x) Pb (Ni _1/3 Nb _2/3 ) O _3- xATiO ₃ (wherein A is at least one selected from Ba, Sr and Ca), Pb (Sc, Ta) O ₃ , (Pb, Ba) ZrO ₃ , or polyvinylidene fluoride. The characteristic of any one of claims 1 to 5, Cooling device. The cooling device according to any one of claims 1 to 6, wherein the cooling member is a heat storage material or a heat sink or a thermal sheet formed of a material having high thermal conductivity. One or more heat storages wherein the cooling member is selected from the group consisting of metal halides, metal nitrates, metal carbonates, metal hydrates, metal oxides, paraffins, fatty acids and ceramic materials The cooling device according to any one of claims 1 to 7, further comprising a material. The cooling device according to claim 8, wherein the heat storage material is vanadium oxide. An electronic component comprising the cooling device according to any one of claims 1 to 9. An electronic apparatus comprising the cooling device according to any one of claims 1 to 9 or the electronic component according to claim 10. A method for cooling a heat source using an ECE element comprising a pair of electrodes and a dielectric portion made of a material exhibiting an electrocaloric effect located between the pair of electrodes,
A part of the ECE element is brought into contact with a heat source directly or through a heat conducting member;
In the ECE element, a temperature gradient is generated between the contact portion with the heat source and another portion,
In the above state, by applying a voltage to the electrode, the dielectric part generates heat,
A cooling method comprising causing the dielectric portion to absorb heat by suspending the application of voltage to the electrode. The cooling method according to claim 12, wherein the temperature gradient in the ECE element is generated by bringing a cooling member into contact with another part. The cooling method according to claim 12, wherein the ECE element is an ECE element in which a plurality of electrodes and a plurality of dielectric portions are alternately stacked. The cooling method according to any one of claims 12 to 14, wherein a voltage is applied in a pulse manner to the electrode of the ECE element.

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