JP5838911B2 - Cooling system - Google Patents

Description

  The present invention relates to a cooling device that cools a heating element using a magnetic fluid as a medium.

  Conventionally, an apparatus described in Patent Document 1 is known as a cooling apparatus that cools equipment using a magnetic fluid. According to Patent Document 1, by applying a magnetic field from the outside to a magnetic fluid in which particles of a magnetic material are dispersed in a solvent, a connection structure in which a plurality of particles included in the fluid are connected to each other is obtained. Is disclosed. Since the heat exchange performance of the magnetic fluid is improved by forming this connection structure, the heat exchange performance of the cooling device can be improved by forming the connection structure in a flow path that requires effective heat exchange.

  Non-Patent Document 1 discloses that the heat exchange performance can be improved by making the shape of the magnetic particles contained in the magnetic fluid more fibrous than spherical.

JP 2011-117688 A

Journal of Japan Society of Refrigerating and Air Conditioning, Vol. 54, No. 626, pp. 13-22

  As in Patent Document 1, in a cooling device that uses a magnetic fluid as a medium for cooling a heat generating device, higher cooling performance is required as the heat generating device becomes more sophisticated. Therefore, the cooling device is required to realize high heat exchange performance using a magnetic fluid containing fibrous magnetic particles described in Non-Patent Document 1.

  On the other hand, when fibrous particles, that is, elongated particles, are flowed into a solvent, it is known that the axis of the particles is directed in a direction parallel to the fluid flow direction. According to the characteristics related to the orientation of the particles, when the above-mentioned connection structure of magnetic particles is formed to improve the heat exchange performance, the direction of the axis of the particles is changed from the direction parallel to the fluid flow direction to the fluid flow direction. Must be changed vertically. Therefore, in order to obtain high-efficiency heat exchange performance, it is necessary to reliably and efficiently change the posture of the particles that can realize the above-described connection structure.

  Therefore, the present invention has been made in view of the above points, and an object of the present invention is to provide a cooling device that exhibits high-efficiency heat exchange performance using a magnetic fluid containing needle-like or fibrous magnetic particles as a heat transport fluid. It is to be.

In order to achieve the above object, the following technical means are adopted. That is, the cooling device according to the present invention includes a magnetic fluid (1) including at least a solvent (2) and needle-like or fibrous magnetic particles (3) dispersed in the solvent, and a fluid in which the magnetic fluid circulates. A circulation circuit (35, 45), a pump for forcibly circulating a magnetic fluid in the fluid circulation circuit, a heating element (34, 42, 44) that is absorbed by the magnetic fluid in the middle of the fluid circulation circuit, and the fluid circulation A magnetic field generator (20) that applies a magnetic field to the magnetic fluid flowing through the circuit, and before the magnetic field is applied to the magnetic fluid by the magnetic field generator, the direction of the axis of the magnetic particles in the magnetic fluid is parallel to the flow of the magnetic fluid with such orientation in which particles posture changing means for changing the orientation of the magnetic particles so as to change the state of the unspecified orientation from the state (10,10A, 10B, 10C, 10D , 10E, 10F) and the
The particle posture changing means is provided separately from the pump in the fluid circulation circuit, and is adjacent to the magnetic field generation device immediately before .

  According to the present invention, when a magnetic field is generated with respect to a magnetic fluid by a magnetic field generation device, a form change that forms a connection structure in which a plurality of magnetic particles are arranged and connected in the magnetic field direction occurs. Due to the shape change, the magnetic particles are oriented in a certain direction, so that the thermal conductivity of the magnetic fluid is improved due to its characteristics. Since the heat absorption capability of the magnetic fluid is enhanced by the shape change, the magnetic fluid having high heat exchange performance can be circulated in the fluid circulation circuit. Furthermore, according to the present invention, the direction of the axis of the magnetic particle can be changed by the particle posture changing means before the form change for forming the connection structure is caused by the magnetic field generation device. Because of this action, the direction of the axis of a large number of fibrous magnetic particles flowing in the fluid circulation circuit is changed from a direction parallel to the fluid flow in the magnetic fluid to a posture indicating an unspecified direction. It is possible to efficiently carry out the shape change that forms the above-described connection structure. Therefore, according to the present invention, it is possible to provide a cooling device that exhibits highly efficient heat exchange performance using a magnetic fluid containing needle-like or fibrous magnetic particles as a heat transport fluid.

It is the schematic diagram which showed the position of the magnetic field formation apparatus and the particle | grain attitude | position change means in the cooling device of 1st Embodiment to which this invention is applied. It is the schematic diagram which showed the structure of the cooling device which concerns on 1st Embodiment. It is the schematic diagram which showed the 1st example about the particle | grain attitude | position change means. It is the schematic diagram which showed the 2nd example about the particle | grain attitude | position change means. It is the schematic diagram which showed the 3rd example about the particle | grain attitude | position change means. It is the schematic diagram which showed the 4th example about the particle | grain attitude | position change means. It is a calculation result for specifying a preferable position regarding the particle posture changing means. It is the schematic diagram which showed the 5th example about the particle | grain attitude | position change means. It is the schematic diagram which showed the 6th example about the particle | grain attitude | position change means. It is the schematic diagram which showed the 7th example about the particle | grain attitude | position change means.

  A plurality of modes for carrying out the present invention will be described below with reference to the drawings. In each embodiment, parts corresponding to the matters described in the preceding embodiment may be denoted by the same reference numerals, and redundant description may be omitted. When only a part of the configuration is described in each mode, the other modes described above can be applied to the other parts of the configuration. Not only combinations of parts that clearly indicate that each embodiment can be specifically combined, but also combinations of the embodiments even if they are not clearly indicated unless there is a problem with the combination. Is also possible.

(First embodiment)
Hereinafter, a magnetic fluid and a cooling device according to a first embodiment of the present invention will be described with reference to FIGS. The magnetic fluid of the present embodiment is a magnetic colloid solution composed of, for example, magnetic fine particles such as magnetite, a surfactant that covers the surface of the magnetic fluid, a base liquid, and the like. . The magnetic fluid is used in various electronic devices, an internal combustion engine of an automobile, an electric motor that generates a driving force for running an electric vehicle or a hybrid vehicle, an inverter that drives the electric motor, a cooling device that cools a secondary battery, and the like.

  As shown in FIG. 1, the magnetic fluid 1 includes at least a solvent 2 and a plurality of fine particles. The plurality of fine particles are aggregates of a plurality of magnetic material particles (hereinafter also referred to as magnetic particles 3), and are dispersed in a solvent. The magnetic particle 3 has a needle shape or a fiber shape. A plurality of such magnetic particles 3 are normally dispersed in a solvent, but are connected and arranged so as to extend in the direction along the magnetic field direction when magnetized (hereinafter referred to as a connection structure). (Also referred to as state 4C). In other words, the plurality of needle-like or fiber-like magnetic particles 3 have a connection structure in which the axes are arranged in a posture that is parallel to the magnetic field direction or extends in the magnetic field direction.

  The form showing this connection structure is maintained as long as there is an influence of remanent magnetization or the like. However, when the connection structure state 4C is released along with the flow of the magnetic fluid 1, the magnetic particles 3 are separated from each other in the solvent 2. A plurality of magnetic particles 3 are dispersed. When shifting to a form change accompanied by the connected structure state 4C, the thermal conductivity of the magnetic fluid 1 is improved as compared with the case of the unconnected structure state 4. On the other hand, when the connection structure is disassembled and transitions to the dispersed state, which is the unconnected structure state 4D, the thermal conductivity is lower than that in the connected structure state 4C, but the viscosity of the fluid is reduced. As described above, the morphological change between the connected structural state 4C and the unconnected structural state 4D is reversible, and the magnetic field is generated with respect to the magnetic fluid 1, the flow of the fluid (change in the flow velocity, the change in the flow direction), Caused by a trigger such as vibration or temperature change.

  The solvent 2 used in the magnetic fluid 1 is an aggregate of solvent molecules, for example, water or an organic substance (for example, ethylene glycol, toluene, etc.). The solvent 2 can be a fluid that disperses the magnetic particles 3 and carries the magnetic particles 3. This fluid may be provided by a liquid or a gas. A fluid may be composed of single or multiple components. For example, water or a liquid polymer can be used as the fluid. Furthermore, a mixture can be used as the fluid. For example, the mixture can be a mixture of water, ethylene glycol, and other functional components.

  Each of the plurality of magnetic particles 3 included in the magnetic fluid 1 is not a sphere but a rod or an elongated shape, and is dispersed in a form surrounded by solvent molecules in the magnetic fluid. The magnetic particle 3 is preferably a material having ferromagnetism, for example, particles made of metal such as iron (Fe), nickel (Ni), manganese (Mn), cobalt (Co), alloys thereof, or oxidation Can be used. Further, the magnetic particle 3 may be composed of two or more kinds of substances.

  As the magnetic particles 3, for example, metal nanorods (nano-sized rod-shaped metal fine particles) having an aspect ratio (a value obtained by dividing the long side of the rod-like particle by the short side) of about 2 to 3 can be used. The magnetic particles 3 may be high-aspect particles having an aspect ratio of, for example, several tens to 100.

The magnetite (Fe ₃ 0 ₄ ) used for the magnetic particles 3 can be obtained by reacting ammonia with a solution of iron (II) chloride and iron (III) chloride. Moreover, the raw material oxide particles of magnetic metal particles, which is an example of the magnetic flower 3, can be produced by, for example, a known metal ion reduction method. The raw material oxide particles of the magnetic metal particles referred to here are those in which the oxide becomes a ferromagnetic metal or alloy by reduction. Specific examples of the raw material oxide particles of the magnetic metal particles include magnetite, Co ferrite, Ni ferrite and the like.

  The magnetic fluid 1 increases or decreases its thermal conductivity by using two states, that is, a connected structure state 4C and unconnected structure states 4 and 4D of a plurality of magnetic particles 3, and the heat exchange performance is improved by the structure formed by the magnetic particles 3. It becomes an adjustable medium. As shown in FIG. 1, the particle orientation changing means 10 is configured to change the direction of the axis of the magnetic particle 3 in the magnetic fluid 1 before the magnetic field is applied to the magnetic fluid 1 by the magnetic field generator 20. It is a device that changes the posture. Therefore, the particle posture changing means 10 is provided at a position upstream of the magnetic field generation device 20 in the pipe 5.

  As shown in FIG. 1, in the pipe 5 in which the magnetic fluid 1 flows in the X direction, on the upstream side of the magnetic field forming portion 22, the magnetic particles 3 are in such a posture that their axes are along the X direction of the fluid flow. (First unconnected structural state 4 shown on the leftmost side in FIG. 1). This is because, when fibrous particles, ie, elongated particles, are flowed into the solvent, the particles have a characteristic that their axes are oriented in a direction parallel to the fluid flow direction. Since the magnetic particles 3 in the first unconnected structure state 4 are arranged relatively regularly in the solvent, they are not in a state of moving randomly.

  The magnetic particles 3 in the first unconnected structural state 4 are regularly arranged in the solvent rather than the first unconnected structural state 4 because the posture is forcibly changed by the particle posture changing means 10. Without moving to a state of moving randomly (second unconnected structure state 4B shown between the particle orientation changing means 10 and the magnetic field generation device 20 in FIG. 1). When a magnetic field is generated in the direction perpendicular to the wall surface (magnetic field generation part 22) of the pipe 5 in the direction from the north pole to the south pole by the permanent magnets 21 constituting the magnetic field generation device 20, it is dispersed upstream. The plurality of magnetic particles 3 that have been magnetized are gathered and assembled into a connected structure state 4C that is arranged and connected so as to be aligned in the magnetic field direction.

  Further, in this connected structure state 4C, the magnetic fluid 1 has an improved thermal conductivity and a higher viscosity than those in the unconnected structure states 4 and 4B due to the characteristics of the magnetic particles that are extended and connected in the magnetic field direction. Become. Next, the magnetic particles 3 that are in the connected structure state 4C at the magnetic field generation site 22 are then released from the third unconnected structure state 4D in which the magnetization is released and the magnetic particles 3 are separated as they flow through the fluid circulation circuit 35. Become. This third unconnected structural state 4D has a lower thermal conductivity and a lower viscosity than in the case of the connected structural state 4C, and further changes to the first unconnected structural state 4 as the fluid flow proceeds. .

  FIG. 2 shows a cooling device 30 that cools the engine 34 that generates the driving force of the automobile, and a cooling device 40 that cools the inverter 44 that drives the electric motor for traveling of the hybrid vehicle.

  The cooling device 30 includes a magnetic fluid 1, a fluid circulation circuit 35 in which the magnetic fluid 1 circulates, a magnetic field generation device 20 that generates a magnetic field for the magnetic fluid 1 flowing in the fluid circulation circuit 35, and a magnetic field generation device 20. And an engine 34 as a heating element that absorbs heat by the magnetic fluid 1 in the middle of the fluid circulation circuit 35. The cooling device 30 further cools the water pump 31 forcibly circulating the magnetic fluid 1 in the fluid circulation circuit 35, the engine radiator 32 provided downstream of the magnetic field generation device 20, and the engine radiator 32. And a thermostat 38 that switches the flow path of the magnetic fluid 1 based on the temperature of the magnetic fluid 1.

  The magnetic field generation device 20 is disposed in the fluid circulation circuit 35 on the upstream side of the heating element engine 34 (upstream side of the portion that absorbs the heat of the heating element). For this reason, the cooling device 30 passes through the particle posture change to the second unconnected structure state 4B by the particle posture changing means 10, and the magnetic particles 3 that are in the connected structure state 4C by the magnetic field generation of the magnetic field generation device 20 The heat conductivity of the magnetic fluid 1 is improved and the heat of the engine 34 can be efficiently absorbed.

  The magnetic field generator 20 is disposed upstream of the engine radiator 32 that radiates the heat of the engine 34 in the fluid circulation circuit 35 (upstream of the portion that radiates the heat of the heating element). For this reason, the cooling device 30 has undergone the change in the posture of the particles to the second unconnected structural state 4B by the particle posture changing means 10, and the cooling device 30 uses the magnetic particles 3 that have become the connected structural state 4C due to the magnetic field generation of the magnetic field generating device 20. The heat conductivity of the magnetic fluid 1 is improved and the heat of the engine 34 can be released efficiently.

  The cooling device 40 includes a magnetic fluid 1, a fluid circulation circuit 45 in which the magnetic fluid 1 circulates, a magnetic field generation device 20 that generates a magnetic field with respect to the magnetic fluid 1 that flows in the fluid circulation circuit 45, and a magnetic field generation device 20. And an inverter 44 as a heating element that absorbs heat by the magnetic fluid 1 in the middle of the fluid circulation circuit 45. Further, the cooling device 40 includes a water pump 41 that forcibly circulates the magnetic fluid 1 in the fluid circulation circuit 45, an HV radiator 43 provided upstream of the magnetic field generation device 20 and the particle orientation changing means 10, and an inverter 44. An electric motor 42 (or a generator) to be driven.

  The magnetic field generation device 20 is disposed upstream of the inverter 44 in the fluid circulation circuit 45 (upstream of a portion that absorbs heat from the heating element). For this reason, the cooling device 40 passes through the change in the posture of the particles to the second unconnected structure state 4B by the particle posture changing means 10, and the magnetic particles 3 that are in the connected structure state 4C by the magnetic field generation of the magnetic field generation device 20 As a result, the thermal conductivity of the magnetic fluid 1 is improved and the heat of the inverter 44 can be absorbed efficiently.

  As described above, the magnetic fluid 1 becomes a cooling medium having a higher thermal conductivity than the unconnected structures 4, 4 </ b> B, 4 </ b> D due to the magnetization of the magnetic particles 3 by the magnetic field generation device 20, and a heat exchange site that requires heat absorption or heat generation. To absorb heat from the outside or dissipate to the outside. Further, the magnetic fluid 1 can be in the unconnected structure state 4 or 4D because the magnetization is weakened at the portion where heat absorption or heat generation is not required in the fluid circulation circuits 35 and 45 (for example, the portions indicated by reference numerals 36 and 37 in FIG. 2). Viscosity due to the formation of the connection structure is reduced, and the fluid circulation circuits 35 and 45 are circulated as a cooling medium having good fluidity with reduced flow resistance.

  Next, a first example of particle posture changing means in the cooling devices 30 and 40 will be described with reference to FIG. As shown in FIG. 3, the particle orientation changing means 10 includes at least one fin member 100 provided in the flow path of the fluid circulation circuits 35 and 45.

  At least one fin member 100 disposed in the flow path of the fluid circulation circuits 35 and 45 changes the flow direction of the magnetic fluid 1 when the magnetic fluid 1 passes through the vicinity thereof. Further, as shown in FIG. 3, the particle orientation changing means 10 may be configured by arranging a plurality of fin members 100 in a staggered manner in the flow path.

  According to the particle posture changing means 10 having this configuration, the magnetic fluid 1 is stirred by the fin member 100 by changing the flow direction thereof. Thereby, since an efficient stirring mechanism of the magnetic fluid 1 can be provided, the direction of the axis of the magnetic particles 3 such as many fibers is parallel to the fluid flow (first unconnected structure). It is possible to shift from the state 4) to the state indicating the unspecified direction (second unconnected structure state 4B). Therefore, it can contribute to forming the connection structure state 4C by the magnetic field generator 20 reliably and efficiently.

  Next, a second example of the particle posture changing means in the cooling devices 30 and 40 will be described with reference to FIG. As shown in FIG. 4, the particle orientation changing means 10 </ b> A includes at least one cylindrical member 100 </ b> A provided in the flow path of the fluid circulation circuits 35 and 45. The cylindrical member 100A forms a Karman vortex on the wake side of the cylindrical member 100A when the magnetic fluid 1 collides. In FIG. 4, the cylindrical member 100 </ b> A is installed with its axial direction oriented in the horizontal direction, but may be arranged with the axial direction oriented in an arbitrary direction including the vertical direction. Further, as shown in FIG. 4, the particle posture changing means 10A has a plurality of columnar members 100A arranged in a direction (flow channel crossing direction) perpendicular to the axial direction (fluid flow direction) of the flow channel. You may comprise by various arrangement | positioning.

  According to the particle orientation changing means 10A having this configuration, the magnetic fluid 1 flowing through the fluid circulation circuits 35 and 45 is agitated by generating at least one cylindrical member 100A to generate Karman vortices. Thereby, since an efficient stirring mechanism can be provided, it is possible to reliably realize a change in form from the first unconnected structure state 4 to the second unconnected structure state 4B with respect to a large number of fibrous particles 3 such as fibers. .

  Next, the 3rd example of the particle | grain attitude | position change means in the cooling devices 30 and 40 is demonstrated with reference to FIG. As shown in FIG. 5, the particle orientation changing means 10 </ b> B includes a plurality of dimples 100 </ b> B formed on the inner wall of the pipe 5 </ b> B that forms the flow paths of the fluid circulation circuits 35 and 45. The plurality of dimples 100B gives a turbulent flow to the magnetic fluid 1 flowing in the vicinity of the inner wall of the pipe 5B, and causes irregular behavior of the magnetic particles 3 along with the turbulence. The plurality of dimples 100B may be formed over the entire circumference or may be partially formed in a predetermined portion of the inner wall of the pipe 5B.

  According to the particle orientation changing means 10B having this configuration, the flow of the magnetic fluid 1 flowing through the fluid circulation circuits 35 and 45 is disturbed from the vicinity of the inner wall of the pipe 5B, and when this disturbance develops, it propagates to the central axis side of the pipe 5B. To come. Thereby, since an efficient stirring mechanism can be provided, it is possible to reliably realize a change in form from the first unconnected structure state 4 to the second unconnected structure state 4B with respect to a large number of fibrous particles 3 such as fibers. .

  Next, a fourth example of particle posture changing means in the cooling devices 30 and 40 will be described with reference to FIG. As shown in FIG. 6, the particle orientation changing means 10 </ b> C is provided with a stirring bar 100 </ b> C that is provided in the flow path of the fluid circulation circuits 35 and 45 and that stirs the magnetic fluid 1. The stirrer 100 </ b> C stirs the magnetic fluid 1 by rotating the blades as the rotation shaft is forcibly driven by a motor or the like.

  According to the particle orientation changing means 10C having this configuration, the flow of the magnetic fluid 1 flowing through the fluid circulation circuits 35 and 45 is disturbed by the rotation of the stirrer 100C, so that an efficient stirring mechanism can be provided. Therefore, according to the particle orientation changing means 10C, the shape change from the first unconnected structure state 4 to the second unconnected structure state 4B can be reliably realized with respect to a large number of fibrous particles 3 such as fibers.

  The particle posture changing means 10 to 10F are provided immediately adjacent to the magnetic field generation device 20 in the fluid circulation circuits 35 and 45. The results will be described with reference to FIG. The inventors have obtained the following findings as a result of performing the calculation under a predetermined condition and examining the results. The inventors set the fiber diameter of the fibrous magnetic particles 3 to 60 nm, the length is 6 μm, the solvent is water, and the diameter of the flow path through which the magnetic fluid 1 flows is 1.4 mm. The average flow velocity is set to two patterns of 0.025 m / s and 0.16 m / s, and the inclination angle of the axis of the magnetic particle 3 with respect to the direction (transverse direction) is perpendicular to the flow axis (fluid flow direction). It was simulated how it changed from the initial angle of 45 degrees.

  As shown in FIG. 7, the inclination angle of the axis line continues to increase from the state of 45 degrees at the initial position at any flow velocity, that is, continues to approach the angle parallel to the fluid flow direction, and the direction of the axis line is For example, the first unconnected structure state 4 is approached. Then, at a position 40 mm away from the initial position, it tilts to about 54 degrees when the average flow velocity is 0.025 m / s and to about 62 degrees when the average flow velocity is 0.16 m / s. From the above, it can be determined that the particle posture changing means 10 to 10F are preferably arranged immediately before the magnetic field generating device 20, for example, adjacent to a place within 50 mm. When the particle orientation changing means 10 to 10F are provided at the upstream further than this, the direction of the axis of the magnetic particle 3 is reliably transferred from the first unconnected structure state 4 to the second unconnected structure state 4B. It is because it is thought that it will become difficult.

  In addition, as a result of intensive studies, the inventors satisfy the following formula 1 between the distance L between the particle orientation changing means 10 to 10F and the magnetic field generation device 20 and various physical property values of the magnetic fluid 1. know.

(Formula 1)
9 × D × (η / η ₀ ) ^1/2 <L <49 × D × (η / η ₀ ) ^1/2
D is the channel diameter (m), η is the viscosity of the solvent 2 (m ² / s), and η ₀ is the viscosity of water (m ² / s).

  Next, a fifth example of the particle posture changing means in the cooling devices 30 and 40 will be described with reference to FIG. As shown in FIG. 8, the particle orientation changing means 10 </ b> D is configured by a magnetic field generating device that generates a magnetic field perpendicular to the wall surface of the pipe 5 through which the magnetic fluid 1 flows. The magnetic field generation device includes an electromagnet 100D that can control the strength of an alternating magnetic field to be generated according to a current value flowing through a coil by an applied voltage. The strength of the magnetic field is adjusted by the control device 6 that controls the applied voltage.

  According to such a configuration, the magnetic particles 3 in the magnetic fluid 1 flowing through the fluid circulation circuits 35 and 45 are not connected to each other by the action of bringing the axis of the particles closer to the magnetic field direction by forming a magnetic field by the electromagnet 100D. It is easy to cause a reliable form change from the first unconnected structure state 4 to the second unconnected structure state 4B via the. Therefore, an efficient fluid stirring function can be exhibited. Further, since the magnetic field is generated by the electromagnet 100D, the strength of the current can be adjusted, and a magnetic field having a desired strength according to the product specifications can be stably generated. Therefore, it is easy to adjust the degree of particle posture change by the particle posture changing means 10D, and it is easy to control the level setting of the heat exchange performance of the cooling devices 30 and 40.

  Next, a sixth example of the particle posture changing means in the cooling devices 30 and 40 will be described with reference to FIG. As shown in FIG. 9, the particle orientation changing means 10E is a permanent magnet 100E (magnetic field generating device) that generates a magnetic field perpendicular to the wall surface of the pipe 5 through which the magnetic fluid 1 flows between a pair of magnetic field forming portions 101E. ). The magnetic field generation device is a particle posture changing means using a single-stage DC magnetic field application method in which one is arranged in the fluid flow direction. Further, as the particle orientation changing means 10F of the seventh example, as shown in FIG. 10, a magnetic field that is perpendicular to the wall surface of the pipe 5 through which the magnetic fluid 1 flows is provided between each of a plurality of sets of magnetic field forming portions 101F. You may employ | adopt the permanent magnet 100F (magnetic field generator) to produce | generate. The magnetic field generation device is a particle posture changing means using a plurality of stages of DC magnetic field application methods arranged side by side in the fluid flow direction.

  According to such a configuration, the magnetic particles 3 in the magnetic fluid 1 flowing through the fluid circulation circuits 35 and 45 are changed from the first unconnected structure state 4 to the second non-connected state by the magnetic field formation by the permanent magnets 100E and 100F. It is easy to cause a sure shape change to the connected structure state 4B. Therefore, an efficient fluid stirring function can be exhibited.

  Below, the effect which the cooling devices 30 and 40 of 1st Embodiment bring is described. The cooling device 30 includes a magnetic fluid 1 including at least a solvent 2 and needle-like or fibrous magnetic particles 3 dispersed in the solvent, a fluid circulation circuit 35 in which the magnetic fluid 1 circulates, and a fluid circulation circuit 35 An engine 34 as a heating element that absorbs heat by the magnetic fluid 1 in the middle, a magnetic field generation device 20 that applies a magnetic field to the magnetic fluid 1 that flows through the fluid circulation circuit 35, and a magnetic field is applied to the magnetic fluid 1 by the magnetic field generation device 20. Before the operation, the particle orientation changing means 10 for changing the orientation of the magnetic particles 3 so as to change the direction of the axis of the magnetic particles 3 in the magnetic fluid 1 is provided.

  According to this, when a magnetic field is generated with respect to the magnetic fluid 1 by the magnetic field generation device 20, a form change (connected structure state 4C) that forms a connection structure in which a plurality of magnetic particles 3 are aligned and connected in the magnetic field direction occurs. . Due to the shape change, the magnetic particles 3 are oriented in a certain direction along with the magnetic field direction, so that the plurality of magnetic particles 3 are connected in a string shape, and the thermal conductivity of the magnetic fluid 1 is improved due to its characteristics. Since this connected structure state 4C is maintained to some extent, the magnetic fluid 1 with improved thermal conductivity flows. Thereby, since the heat absorption capability of the magnetic fluid 1 is strengthened, the magnetic fluid 1 having high heat absorption can be circulated in the fluid circulation circuit.

  Further, the orientation of the magnetic particles 3 can be changed by the particle orientation changing means 10 before the magnetic field generating device 20 changes the form of forming the connected structure state 4C. By this action, the direction of the axis of the magnetic particles 3 such as a number of fibers flowing in the fluid circulation circuit 35 is changed from a direction parallel to the fluid flow in the magnetic fluid 1 to an unspecified direction. Thereby, the form change which forms the connection structure state 4C from the 1st connection state 4 through the 2nd connection state 4B can be implemented efficiently. Therefore, according to the cooling device of the first embodiment, highly efficient heat exchange performance can be exhibited using the magnetic fluid 1 containing the needle-like or fibrous magnetic particles 3 as the heat transport fluid.

  The magnetic field generator 20 generates a magnetic field that is perpendicular to the wall surface of the pipe 5 through which the magnetic fluid 1 flows. According to this configuration, by forming a magnetic field in such a direction, the magnetic particles 3 are in a preferable connected structure state 4C, and a preferred particle orientation for heat conduction is obtained, and heat exchange with the wall of the pipe 5 is achieved. Can be formed efficiently.

  Further, according to the cooling device 30, if the magnetic field generation device 20 and the particle posture changing means 10 generate a magnetic field at a desired portion (magnetic field generation portion 22) of the fluid circulation circuit 35 through which the cooling water circulates, It becomes possible to efficiently absorb the heat of the engine 34 by exchanging heat between the coolant having improved thermal conductivity and the heat of the engine 34 by forming the connection structure state 4C. Therefore, improvement in engine operability and reliability can be achieved by improving engine cooling performance.

  Further, according to the cooling device 40, if the magnetic field generation device 20 and the particle posture changing means 10 generate a magnetic field at a desired portion (magnetic field generation portion 22) of the fluid circulation circuit 45 through which the cooling water circulates, Improvement of inverter cooling performance can contribute to improvement of inverter reliability.

(Other embodiments)
The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. The structure of the said embodiment is an illustration to the last, Comprising: The scope of the present invention is not limited to the range of these description. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

  As the solvent contained in the magnetic fluid, the following organic solvents can be used in addition to those exemplified in the above embodiments. Examples of the organic solvent include toluene, hexane, diethyl ether, chloroform, ethyl acetate, tetrahydrofuran, methylene chloride, acetone, acetonitrile, N, N-dimethylformamide, dimethyl sulfoxide, butanol acetate, 2propanol, 1-propanol, ethanol, methanol. , Formic acid and the like.

  Moreover, you may use what consists of two types of components as a solvent contained in a magnetic fluid. Of these, one kind of solvent may be a liquid having a freezing point depressing action. For example, water can be used as the solvent, and potassium acetate, sodium acetate, or the like can be used as the freezing point depressant. According to such a structure, the practicality in a cold district etc. can be further improved by lowering the freezing point of the magnetic fluid. Furthermore, if necessary, in addition to the freezing point depressant, a rust inhibitor and an antioxidant may be added to the magnetic fluid as additives. If there is no need to lower the freezing point of the magnetic fluid, two or more types of solvents that do not contain a freezing point depressant may be used.

  In the above embodiment, when ethylene glycol is used as the solvent, it has a freezing point lowering action, and the freezing point of the solvent can be lowered to, for example, about −20 ° C. That is, for example, when the cooling device targets the engine for cooling, the practicality in a cold district such as in-vehicle cooling water or oil becomes better.

  One magnetic field generation device 20 in the above embodiment is provided for the magnetic field generation portion 22. However, when the range of the part requiring heat exchange is long or large, or in a part where it is difficult to physically install the magnetic field generating device such as a part that generates high temperature heat, the magnetic field generating apparatus can satisfy the request. A plurality of fluid circulation circuits 35 and 45 may be installed.

  In addition, the cooling device of each of the above embodiments is used in a cooling device for a semiconductor component such as a CPU, LSI, CCD, etc., as well as a device for radiating heat from an engine, an inverter, a secondary battery, an electronic device, etc., and a cooling device for a motor. It can also be applied.

DESCRIPTION OF SYMBOLS 1 ... Magnetic fluid 2 ... Solvent 3 ... Magnetic particle 10, 10A, 10B, 10C, 10D, 10E, 10F ... Particle posture change means 20 ... Magnetic field generator 30, 40 ... Cooling device 35, 45 ... Fluid circulation circuit 34 ... Engine (Heating element)
42 ... Electric motor (heating element)
44 ... Inverter (heating element)

Claims (5)

A magnetic fluid (1) comprising at least a solvent (2) and acicular or fibrous magnetic particles (3) dispersed in the solvent;
A fluid circulation circuit (35, 45) through which the magnetic fluid circulates;
A pump for forcibly circulating the magnetic fluid in the fluid circulation circuit;
A heating element (34, 42, 44) that is absorbed by the magnetic fluid in the middle of the fluid circulation circuit;
A magnetic field generator (20) for applying a magnetic field to the magnetic fluid flowing through the fluid circulation circuit;
Before the magnetic field is applied to the magnetic fluid by the magnetic field generation device, the direction of the axis of the magnetic particles in the magnetic fluid is changed from a state parallel to the flow of the magnetic fluid to an unspecified direction. Particle posture changing means (10, 10A, 10B, 10C, 10D, 10E, 10F) for changing the posture of the magnetic particles so as to change;
Equipped with a,
In the fluid circulation circuit, the particle posture changing means is provided separately from the pump, and is adjacent to the magnetic field generation device immediately before the cooling device.   The cooling apparatus according to claim 1, wherein the particle posture changing means (10) includes at least one fin member (100) provided in a flow path of the fluid circulation circuit. The particle posture changing means (10A) is composed of at least one cylindrical member (100A) provided in the flow path of the fluid circulation circuit,
The cooling apparatus according to claim 1, wherein the cylindrical member forms a Karman vortex by the collision of the magnetic fluid.   2. The cooling according to claim 1, wherein the particle posture changing means (10 </ b> C) includes a stirrer (100 </ b> C) that is provided in a flow path of the fluid circulation circuit and stirs the magnetic fluid by rotating. apparatus. The particle position change means (10B) is according to claim 1 to claim 4, characterized in that it consists of a plurality of dimples formed on the inner wall of the pipe (5B) for forming a flow path of the fluid circulation circuit (100B) The cooling device according to any one of the above.

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