JP2005079242A - Electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic apparatus which can be improved in characteristics and reliability by protecting components having low heat resistance from heat dissipated from a heating component and which can be reduced in size and thickness. <P>SOLUTION: On the bottom inside a housing 10 formed of a material having a low thermal conductivity, PEFC1 which is the heating component whose surface is pasted with an aluminum foil and hence its surface emissivity is suppressed to not less than 0.04 nor more than 0.3 is located via heat insulating spacers 5. An air blower 6 for air-cooling the PEFC1 is located on the side of the PEFC1. On the top face side inside the housing 10, an electrolytic capacitor 2 and a memory disc 3, which are the components having a low heat resistance, are located. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electronic device incorporating a heat generating component, and more particularly to an electronic device incorporating a fuel cell as a heat generating component.

    In recent years, portable electronic devices such as mobile phones and notebook personal computers (hereinafter abbreviated as “notebook personal computers”) are required to be lighter, smaller and thinner, and to be used for a long time. Therefore, there is a demand for a power source that is light and small in size and has a high energy density. Among power sources that are currently popular, lithium ion secondary batteries have the highest energy density, but there is a need for a power source that has a higher energy density. A fuel cell, which is one of the power sources, generates electricity by an electrochemical reaction. Among them, a polymer electrolyte fuel cell (hereinafter referred to as PEFC) and a solid oxide fuel cell (Solid). Oxide Fuel Cell (hereinafter referred to as SOFC) is expected as a power source capable of realizing a high energy density.

    In PEFC and SOFC, heat is generated during power generation. For example, in the case of PEFC that generates power by supplying hydrogen to the fuel electrode and oxygen in the air to the oxidizer electrode, theoretically, per cell. A voltage of 1.2 volts is produced, but generally the actual voltage obtained is 0.4 to 0.6 volts, and the difference between the theoretical voltage and the actual voltage obtained, ie 0.6 to 0.8. Electrical energy corresponding to voltage in volts is converted into thermal energy. For example, when power generation of 15 watts is performed in PEFC, heat generation of 15 to 30 watts is accompanied.

    On the other hand, it is desirable to operate the power supply so that it can generate electric power at a higher output from the viewpoint of weight reduction and miniaturization of the power supply. Therefore, in PEFC and SOFC, in order to generate electric power at high output, Is preferably kept higher than room temperature. For example, the amount of power generated when the PEFC is operated at 25 ° C. is 2 watts, and the amount of heat generated at this time is 4 watts, whereas the amount of power generated when operated at 80 ° C. is 13 watts. The calorific value at this time is 26 watts. Therefore, in PEFC, in order to obtain a high output, temperature control is performed so that the temperature during the power generation operation is maintained at about 70 to 130 ° C. In addition, in SOFC, the amount of power generated when operated at 25 ° C. is 0.2 watts, and the amount of heat generated at this time is 0.4 watts, whereas the amount of heat generated when operated at 400 ° C. The power generation amount is 13 watts, and the heat generation amount at this time is 26 watts. Therefore, in SOFC, in order to obtain a high output, temperature control is performed so that the temperature during the power generation operation is maintained at least at 400 ° C. or more.

    As described above, in an electronic device equipped with a PEFC or SOFC as a power source, the temperature of the PEFC or SOFC is maintained at a high temperature during operation, and these generate heat due to power generation. Therefore, a large amount of heat is dissipated from the PEFC or SOFC to the surroundings. For this reason, PEFC and SOFC are hereinafter referred to as heat generating components.

    By the way, an electronic device equipped with a PEFC or SOFC as a power source has a low heat resistance component (hereinafter referred to as a low heat resistance component) in addition to a heat generating component such as a PEFC or SOFC. Here, the low heat-resistant component is a component whose specified maximum temperature is lower than the temperature during operation of the heat generating component. For example, examples of the low heat resistant parts include electrolytic capacitors, crystal elements, image pickup elements, IC cards, batteries, storage disks, etc., and the specified maximum operating temperatures of these parts are 85 ° C., 80 ° C., 60 ° C., respectively. ° C, 60 ° C, 60 ° C, 40 ° C. Such low heat-resistant components cause performance degradation, malfunction, shortening of life, etc. when operated at a temperature higher than the maximum specified temperature, resulting in the characteristics and reliability of electronic equipment. Adversely affect. Therefore, in an electronic device incorporating a heat generating component and a low heat resistant component, it is necessary to protect the low heat resistant component from the heat radiated from the heat generating component, and thus it is necessary to devise a heat dissipation method in the device. Such a problem is not limited to the case where the heat-generating component is a PEFC or SOFC. In addition to this, for example, an electronic device including a power supply module or the like also becomes a problem.

By the way, there are three modes of heat transfer from the heat generating component to the surroundings: conduction heat transfer, convection heat transfer, and radiant heat transfer. The amount of heat transferred from the heat generating component to the surroundings (heat dissipation amount) is The total amount of heat in each heat transfer. In the heat conduction, heat of the heat generating portion is transferred to the surroundings through a member that contacts the heat generating component, for example, a housing to which the heat generating component is attached. Convective heat transfer is heat transfer by air. Radiant heat transfer is heat transfer by heat rays such as infrared rays emitted from a heat generating portion. The heat transfer amount increases as the temperature of the heat generating component increases and the surface area of the heat generating component increases. For example, when the heat generating component has a general value (specifically, 0.95) of emissivity with respect to infrared rays having a wavelength of around 10 micrometers, the surface temperature is 125 ° C. and the surface area is 100 cm ² , the temperature The amount of heat released by radiant heat transfer to the surroundings at 25 ° C. is 9 watts.

    In order to protect the low heat resistant component from the heat radiated from the heat generating component, it is necessary to suppress the heat transfer to the low heat resistant component. As a method for suppressing heat transfer, for example, by reducing the cross-sectional area of a portion where the heat generating component contacts (for example, a casing to which the heat generating component is attached), the heat is transmitted from the heat generating component to the low heat resistant component by conduction heat transfer. The amount of heat transfer can be easily reduced. Also, by quickly discharging air heated by convective heat transfer from the inside of the electronic equipment to the outside, the amount of heat transfer by convective heat transfer increases, thereby suppressing conduction heat transfer and radiant heat transfer from the heat-generating components. As a result, heat dissipation to the low heat resistant component is suppressed.

On the other hand, as a method for suppressing radiant heat transfer, for example, there is a method in which an inner surface of a housing of an electronic device that houses a low heat resistance component and a heat generating component is configured to have a low emissivity (for example, Patent Document 1). reference). According to such a configuration, it is possible to suppress heat transferred from the heat generating component to the housing from being transmitted from the housing to the low heat resistant component by radiant heat transfer. Moreover, there exists a thing of the structure which has arrange | positioned the infrared-reflection board between a heat-emitting component and a low heat resistant component (for example, refer patent document 2). According to such a configuration, since the heat rays emitted from the heat generating component can be reflected by the infrared reflector, the low heat resistant component does not receive heat radiation directly from the heat generating component, and thus the temperature of the low heat resistant component is reduced. The rise can be suppressed.
Japanese Patent Laid-Open No. 2001-210980 JP 2001-148593 A

    As described above, the method for reducing the emissivity of the inner surface of the casing of the electronic device is based on the premise of conduction heat transfer from the heat generating component to the casing, and therefore, the low heat resistant component is thermally separated from the casing. There is a need. For this reason, the degree of freedom of arrangement of the low heat-resistant components in the electronic device is remarkably lowered, and the device is hindered from being reduced in size and thickness. Further, if the temperature of the case touched by human hands rises due to conduction heat transfer, there is a risk of burns when touching the case. On the other hand, the method of placing an infrared reflector between a heat-generating component and a low heat-resistant component requires a space for the arrangement of the infrared reflector, which increases the size of the device and makes it difficult to reduce the size and thickness. It becomes.

    An object of the present invention is to provide an electronic device that has improved characteristics and reliability by protecting a low heat-resistant component from heat dissipation of a heat-generating component, and that can be reduced in size and thickness.

      In order to solve the above-described problems, an electronic device according to the present invention includes a heat-generating component including a power supply unit and a low heat-resistant component having a maximum use temperature lower than a temperature during operation of the heat-generating component. In the above, at least a part of the surface of the heat generating component has an emissivity of 0.04 or more and 0.3 or less with respect to infrared rays having a wavelength of around 10 micrometers.

      According to this configuration, it is possible to reduce the amount of heat radiated from the surface of the power generation component to the surroundings by radiant heat transfer, and thus it is possible to suppress the temperature rise of the low heat resistance component. Accordingly, it is possible to prevent the performance of the low heat resistant component from being deteriorated, the occurrence of malfunction, and the shortening of the lifetime, and the characteristics, reliability, and durability of the electronic device can be improved. Here, the surface refers to the surface of the case when the heat generating component houses the component in the case.

      The emissivity is more preferably 0.04 or more and 0.1 or less.

  The heat generating component may be a power supply module.

  The heat generating component may be a fuel cell, for example, a polymer electrolyte fuel cell or a solid oxide fuel cell.

  In such a configuration, in the polymer electrolyte fuel cell and the solid oxide fuel cell, the temperature during the power generation operation is maintained at a high temperature in order to obtain a high output. Here, in a fuel cell having a low surface emissivity as described above, radiation heat transfer to the surroundings is suppressed and it becomes possible to confine the heat inside itself, so this heat is maintained at its own temperature. Can be used. Therefore, it is possible to effectively use heat while suppressing heat radiation to the low heat resistant component. In particular, when the emissivity is 0.04 or more and 0.1 or less, not only the temperature holding effect during power generation but also the effect of shortening the time required for starting the fuel cell due to heat confinement can be obtained.

  The low heat-resistant component may be any one of an electrolytic capacitor, a crystal device, an image sensor, an IC card, a battery, and a storage disk.

  The heat generating component and the low heat resistant component may be arranged inside a housing, and may be configured to be able to suppress conduction heat transfer through the housing of heat generated by the heat generating component, The conduction heat transfer may be suppressed by insulating the heat generating component. For example, the housing may be made of a heat insulating material, and a heat insulating material may be disposed between the housing and the heat generating component.

  The heat generating component and the low heat resistant component may be disposed inside a housing, and may include a cooling unit that cools the heat generating component by convective heat transfer. For example, the housing may have an air outlet for discharging internal air to the outside and an air inlet for taking external air into the inside, and the cooling means may be a blower.

  At least a part of the surface of the heat-generating component may be composed of a flat metal surface, and the metal surface may be composed of a metal oxide. For example, the metal oxide may be magnesium oxide or aluminum oxide.

    According to the present invention, in an electronic device incorporating a heat-generating component and a low heat-resistant component, heat dissipation from the heat-generating component to the low heat-resistant component can be significantly suppressed, so that an increase in temperature of the low heat-resistant component can be suppressed. I can do it. Accordingly, in the electronic device, it is possible to prevent the performance degradation and malfunction of the low heat resistant component, and to stably obtain good characteristics and high reliability.

    Embodiments of the present invention will be described below with reference to the drawings. Here, a notebook personal computer will be described as an electronic device.

    FIG. 1 is a schematic cross-sectional view showing an internal configuration of an electronic apparatus (notebook personal computer) according to an embodiment of the present invention. Note that FIG. 1 shows only the configuration necessary for describing the features of the present invention, and illustration and description of other configurations are omitted.

    As shown in FIG. 1, an electronic device includes a PEFC 1 that is a fuel cell that is a heat-generating component, a first substrate 11 on which an electrolytic capacitor 2 and a storage disk 3 that are low heat-resistant components are disposed in a housing 10, A second substrate 12 on which a lithium ion secondary battery 4 as a low heat resistant component is disposed and a blower 6 for air-cooling the PEFC 1 are built in.

    The housing 10 has a rectangular thin box shape, and includes a top surface and a bottom surface forming a pair of main surfaces, and side surfaces disposed on the outer periphery of the main surface. A plurality of through holes are formed in a pair of opposing side surfaces, whereby an air outlet 13 for discharging the air in the housing 10 to the outside and an external air to be introduced into the housing 10 Air inlet 14 is provided. The housing | casing 10 is comprised from the material with small heat conductivity so that it may have heat insulation. For example, here, the casing is made of a polycarbonate-based resin having a thermal conductivity of 0.19 W / (m · k).

  A first substrate 11, which is a circuit substrate on which various electronic components such as the electrolytic capacitor 2 and the storage disk 3 are mounted, is disposed on the upper surface side inside the housing 10. On the other hand, a second substrate 12 that is a printed wiring board on which the lithium ion secondary battery 4 is disposed is disposed on the bottom surface side. The first substrate 11 and the second substrate 12 are each attached to the inner surface of the housing 10 by, for example, an adhesive. Therefore, the first substrate 11 and the second substrate 12 are thermally connected to the housing 10 respectively, and the substrates 11 and 12 are arranged apart from each other with a space therebetween. . Although not shown here, the first substrate 11 and the second substrate 12 are electrically connected as in the conventional configuration. The PEFC 1 is disposed on the bottom surface side of the housing 10 with a space 5 formed between the bottom surface of the housing 10 and the spacer 5 made of a heat insulating material. Therefore, the housing 10 and the PEFC 1 are thermally insulated. Also, a blower 6 having a fan is disposed so as to send wind to the PEFC 1 from the side surface side.

    As will be described later, during operation of the electronic device, the PEFC 1 that is a power source is at a higher temperature (about 70 to 130 ° C.) than other surrounding components. Therefore, here, PEFC1 corresponds to a heat generating component. On the other hand, the electrolytic capacitor 2, the storage disk 3, and the lithium ion secondary battery 4 have the specified maximum use temperatures of 85 ° C., 40 ° C., and 60 ° C., respectively, which is the highest use temperature than the operating temperature of PEFC 1. The temperature is low. Therefore, here, the electrolytic capacitor 2, the storage disk 3, and the lithium ion secondary battery 4 correspond to low heat resistant components.

    The PEFC 1 is configured such that the surface has an emissivity of 0.04 or more and 0.3 or less with respect to infrared rays having a wavelength of about 10 micrometers. For example, in such a configuration, a metal foil or a metal plate such as aluminum or stainless steel whose surface is polished or plated and is flattened is attached to the surface of PEFC1, or a metal oxide such as aluminum oxide or magnesium oxide is attached. This can be realized by coating the surface of PEFC 1 to form a flat surface. When the metal oxide is aluminum oxide or magnesium oxide, durability can be improved. The PEFC 1 may have a configuration in which a part of the surface is applied, or may have a configuration in which the entire surface is applied. Here, the entire surface of the PEFC 1 has such a configuration, and the emissivity of the entire surface is within this range.

    Many of the substances existing in the natural world have an emissivity of 0.9 or more on the surface, and in particular, a surface state with an emissivity of 0.3 or less cannot be produced unintentionally. Further, the emissivity of the surface of PEFC1 and the amount of radiant heat transfer from PEFC1 are proportional to each other, and the smaller the emissivity of the surface of PEFC1, the lower the amount of radiant heat transfer, which is preferable from the viewpoint of protecting low heat resistant parts A surface state with an emissivity of less than 0.04 can only be achieved with a very flat metal surface, and it is not practical to form such a metal surface because of the high cost. Therefore, the emissivity of the surface of PEFC1 is preferably in the range of 0.04 or more and 0.3 or less.

    The emissivity is defined for infrared rays in the vicinity of a wavelength of 10 micrometers for the convenience of considering that the wavelength to be measured by the radiation thermometer used is often in this wavelength range. The wavelength is not limited to the above as long as the same effect is obtained with respect to infrared radiation.

    In PEFC1, the emissivity is more preferably 0.04 or more and 0.1 or less. As described above, if the emissivity is 0.04 or more and 0.3 or less, the amount of radiant heat transfer can be sufficiently reduced. However, by setting the emissivity to 0.04 or more and 0.1 or less, the following is achieved. In addition, the startup time of PEFC 1 can be shortened.

    That is, in PEFC1, since the electrochemical activity of platinum or a ruthenium alloy as a catalyst depends on temperature, a high output cannot be obtained at room temperature. Therefore, normally, PEFC1 is heated to a predetermined temperature. In the meantime (ie, at the time of startup), the lithium ion secondary battery 4 connected to the hybrid is operated as a power source to cover the output, while the temperature of the PEFC 1 is raised. Here, paying attention to the correlation between the temperature rise time of PEFC1 and the emissivity of the surface of PEFC1, the temperature rise time of PEFC1 is determined by the emissivity, and if the emissivity is small, heat dissipation due to radiant heat transfer is suppressed. The heat generated in PEFC1 is confined inside itself and used for heating itself. Therefore, the temperature of PEFC 1 is quickly increased. For example, when the emissivity is 0.3, it takes 1 minute to raise the temperature of PEFC1 to 130 ° C., whereas when the emissivity is 0.1, the temperature rise time is 20 seconds. Shortened to If the temperature raising time of the PEFC 1 is shortened in this way, it is possible to reduce the capacity of the lithium ion secondary battery 4 used as a hybrid power source at the time of start-up. As a result, the electronic device is reduced in size and thickness. Can be realized.

    Next, the behavior of heat during the operation of the electronic device will be described.

    At the beginning of the operation of the electronic device (that is, at the time of startup), as described above, the device is operated using the lithium ion secondary battery 4 as a power source until the temperature at which the PEFC 1 can obtain a sufficient output. When the PEFC 1 is sufficiently heated, the operation of the lithium ion secondary battery 4 is stopped, the PEFC 1 is operated as a power source, and the PEFC 1 is air-cooled by the blower 6 so that the PEFC 1 is maintained at an optimum temperature for power generation. To do.

    In PEFC1, the air supplied to the oxidant electrode reacts with the fuel supplied to the fuel electrode to generate power. Along with the power generation reaction, a large amount of heat is generated in PEFC1. Since the heat obtained by this power generation reaction and the high temperature optimal for power generation are maintained, PEFC 1 has a higher temperature than the surroundings. Therefore, heat is transmitted from the PEFC 1 to the surroundings by conduction heat transfer, convection heat transfer, and radiant heat transfer to perform heat dissipation. Hereinafter, heat dissipation in each heat transfer method will be described in detail.

    First, in conduction heat transfer, the heat of PEFC 1 is transferred to the casing 10 to which the PEFC 1 as a heat generating component is attached. The amount of heat transfer in conduction heat transfer is the thermal conductivity of the material constituting the housing 10, the contact area between the housing 10 and PEFC 1, the cross-sectional area of the housing 10, the heat transfer distance, and the housing 10 and PEFC 1. It depends on the temperature difference. Here, as described above, the housing 10 is made of a material having a low thermal conductivity, and the spacer 5 made of a heat insulating material is disposed between the bottom surface of the housing 10. In this configuration, conduction heat transfer from the PEFC 1 to the housing 10 is suppressed. Therefore, the amount of heat transferred from the PEFC 1 to the electrolytic capacitor 2, the storage disk 3, and the lithium ion secondary battery 4 through the casing 10 by conduction heat transfer is also reduced. Moreover, since the temperature rise of housing | casing 10 itself is also suppressed, safety | security improves.

    Convective heat transfer is heat transfer by air, and in the above configuration in which the air blower 6 is provided to cool the PEFC 1, convective heat transfer is performed as follows. That is, the rotation of the fan of the blower 6 forms an air flow toward the PEFC 1 in the housing 10, and heat is transferred from the PEFC 1 to the air. The air to which heat has been transferred is discharged to the outside from the air outlet 13 of the housing 10, while air at room temperature is newly taken into the housing 10 from the outside through the air inlet 14 of the housing 10.

    The amount of heat transfer in such convective heat transfer is determined by the wind speed of the wind (air) sent from the blower 6 to the PEFC 1, the temperature difference between the wind and the PEFC 1, and the surface area of the portion where the wind strikes. Here, since the surface area of the portion to which the wind hits is large and the temperature difference between the sent wind and the PEFC 1 is large, it is realistic to use the blower 6 that can be built in the housing 10 and has low power consumption. Air cooling can be performed at a high wind speed, and a large amount of heat can be released to the outside together with air. Therefore, the heat transfer amount of the convection heat transfer, in other words, the heat release amount to the outside of the device using the convection heat transfer increases, and the PEFC 1 is cooled. By the way, the heat transfer amount from PEFC1 to the surroundings is the sum of the heat transfer amounts in the three heat transfer methods as described above, and since this sum is substantially constant according to the output of PEFC1, the convection heat transfer is performed as described above. When the amount of heat transfer in increases, the amount of heat transfer in conduction heat transfer and radiation heat transfer is reduced. Therefore, as a result, the amount of heat transferred from the PEFC 1 to the electrolytic capacitor 2, the storage disk 3, and the lithium ion secondary battery 4 is reduced.

    In radiant heat transfer, the amount of heat transfer is determined by the emissivity of the surface of the PEFC 1, the surface area, and the temperature difference between the surroundings where the heat is transferred and the PEFC 1. In particular, the emissivity and the amount of heat transfer are in a proportional relationship. Therefore, by reducing the emissivity of the surface of PEFC1 to 0.04 or more and 0.3 or less, more preferably 0.04 or more and 0.1 or less. The amount of heat transfer due to radiant heat transfer can be suppressed, and therefore the amount of heat transfer due to radiant heat transfer from the PEFC 1 to the electrolytic capacitor 2, the storage disk 3, and the lithium ion secondary battery 4 can be reduced. . In addition, by suppressing the heat radiation from the surface of PEFC1 in this way, the heat generated in PEFC1 is used to maintain the temperature of the battery itself, so that it is possible to maintain a temperature state in which high output is possible in PEFC1. Become.

    As described above, in the electronic device of the present embodiment, it is possible to suppress conduction heat transfer and radiant heat transfer of heat generated in PEFC 1 while promoting convective heat transfer. 2, the heat transfer to the storage disk 3 and the lithium ion secondary battery 4 is suppressed, and the temperature rise of these components can be prevented. Therefore, it is possible to prevent the performance of these low heat-resistant parts from being deteriorated, the occurrence of malfunction, the shortening of the service life, and the like, and as a result, the characteristics, reliability, and durability of the electronic device are improved.

    In addition, the configuration in which the surface of the PEFC 1 has a low emissivity can be easily realized by a method such as attaching a metal foil to the surface of the PEFC 1 as described above. There is no space limitation as in the conventional case in which an infrared reflector is disposed between components. Therefore, the degree of freedom of arrangement of the components in the electronic device is increased, and the entire electronic device can be reduced in size and thickness. Therefore, it is particularly effective in portable electronic devices. Moreover, since conduction | electrical_connection heat transfer is suppressed, the high temperature of the housing | casing 10 can be prevented and safety | security improves accordingly.

    In the above description, the case where the electronic device includes PEFC1 that is a fuel cell as a heat generating component has been described. However, the present invention can also be applied to an electronic device including a fuel cell other than PEFC1 as a heat generating component. For example, as a modification of the present embodiment, a configuration provided with SOFC as a heat generating component may be used. In this case, the operating temperature during power generation of the SOFC is 400 ° C. or higher, which is higher than the operating temperature of the PEFC. Therefore, the effect of suppressing heat transfer from the SOFC to the low heat-resistant component is more effectively achieved, and the self-inside The effect of using the trapped heat to maintain its own temperature is more effective. In particular, in SOFC, in addition to the electrochemical activity of the catalyst, the ionic conductivity of the electrolyte is temperature-dependent, so power generation is not possible at room temperature. Therefore, it is necessary to wait until the temperature reaches a predetermined high temperature at startup. However, in such a configuration, since the radiant heat transfer can be suppressed and the heat can be effectively used to increase its own temperature even at the time of start-up, the effect of shortening the start-up time is further effectively exhibited.

    Furthermore, the present invention can be applied to an electronic device provided with a power generation component other than a fuel cell as a heat generating component. For example, the power supply module may be an electronic device corresponding to the heat generating component. Here, the power supply module includes a power conversion device as a main component, and is, for example, an ultra-small turbine generator. Here, the fuel cell and the power supply module are collectively referred to as a power supply unit.

    The heat generating component is not limited to a power generating component such as a power supply unit. However, since the heat generating component usually generates a lot of heat, it can be said that the power generating component is a heat generating component. In an electronic device including a heat generating component such as a power generation component, the effect of the present invention is more effectively exhibited as the heat generation amount of the heat generating component is larger and the surface area thereof is larger. Further, the above-described PEFC and SOFC As described above, in the case where it is necessary to maintain a high temperature during operation, heat can be confined in the self and the heat can be utilized for maintaining the temperature of the self, so that the effect of the present invention is more effectively exhibited.

    Further, the low heat-resistant component is not limited to the electrolytic capacitor, the storage disk, and the lithium ion secondary battery, but may be other than this. The lower the maximum operating temperature of the low heat resistant component and the larger the surface area of the component, the more effective the effect of the present invention.

In the above description, the notebook personal computer is described as the electronic device. However, the present invention can be applied to other electronic devices, and in particular, the heat generating component and the low heat-resistant component are arranged close to each other. A more advantageous effect is achieved in portable devices that have been made more efficient.
(Example 1)
A notebook personal computer having the structure shown in FIG. 1 was produced, and the amount of heat released to the surroundings during the power generation operation of the PEFC 1 and the temperature of the electrolytic capacitor 2 at this time were measured.

In the PEFC 1 of this example, the power generating unit that generates heat has dimensions of 70 mm long × 70 mm wide × 10 mm high, has a volume of 49 cc, and has a surface area of 126 cm ² . A commercially available stainless steel plate having a thickness of 0.05 mm, whose surface is appropriately polished, is attached to the entire power generation unit of PEFC 1 with an adhesive. The emissivity of the surface of the power generation section of PEFC1 with respect to infrared rays having a wavelength of around 10 micrometers was 0.3 as measured by a radiation thermometer. The PEFC 1 is disposed on the bottom surface of the casing 10 through a heat insulating spacer 5 made of silica. The spacer 5 has a thermal conductivity of 0.1 watt / mK and a size of 5 mm in length × 5 mm in width. X Height is 3 mm.

With this configuration, the amount of heat generated from the PEFC 1 is 25 watts, and air (air) is sent from the blower 6 to the entire surface of the power generation unit of the PEFC 1 at a wind speed of 2.6 m / sec. did. When the amount of heat released from PEFC 1 at this time was measured, the amount of heat released by conduction heat transfer was 0.3 watts, the amount of heat released by convection heat transfer was 22.3 watts, and the amount of heat released by radiant heat transfer was 0.2 watts. It was 3 watts. And the maximum temperature of the electrolytic capacitor 2 at this time was 85 degreeC, and was below the heat-resistant temperature.
(Example 2)
A notebook personal computer similar to that of Example 1 was prepared except that the emissivity of the surface of the power generation unit of PEFC1 was 0.04, and the amount of heat released during the power generation operation of PEFC1 was measured in the same manner as in Example 1.

With such a configuration, the amount of heat generated from the PEFC 1 is 25 watts, air (air) is sent from the blower 6 at a wind speed of 3.2 m / sec to the entire surface of the power generation unit of the PEFC 1, and air cooling is performed. did. When the amount of heat released from PEFC 1 at this time was measured, the amount of heat released by conduction heat transfer was 0.2 watts, the amount of heat released by convection heat transfer was 24.5 watts, and the amount of heat released by radiant heat transfer was 0.2 watts. It was 3 watts. At this time, the maximum temperature of the electrolytic capacitor 2 was 75 ° C., which was lower than the heat resistance temperature.
(Example 3)
Instead of the stainless steel plate, a 0.5 mm-thick magnesium oxide plate with an appropriately polished surface is disposed on the surface of the power generation unit of PEFC1, and the emissivity of the surface of the power generation unit is set to 0.29. A notebook computer having the same configuration as that of No. 1 was produced. In the same manner as in Example 1, the amount of heat released during the power generation operation of PEFC 1 was measured.

With this configuration, the amount of heat generated from the PEFC 1 is 25 watts, air (air) is sent from the blower 6 at a wind speed of 2.7 m / sec to the entire surface of the power generation unit of the PEFC 1, and air cooling is performed. did. When the amount of heat released from PEFC 1 at this time was measured, the amount of heat released by conduction heat transfer was 0.2 watts, the amount of heat released by convection heat transfer was 22.4 watts, and the amount of heat released by radiant heat transfer was 2.2. It was 4 watts. At this time, the maximum temperature of the electrolytic capacitor 2 was 84 ° C., which was lower than the heat resistance temperature.
Example 4
Instead of the stainless steel plate, a 0.5 mm-thick aluminum oxide plate with a moderately polished surface is placed on the surface of the power generation unit of PEFC1, and the emissivity of the surface of the power generation unit is set to 0.1. A notebook computer having the same configuration as that of No. 1 was produced. In the same manner as in Example 1, the amount of heat released during the power generation operation of PEFC 1 was measured.

With this configuration, the amount of heat generated from PEFC 1 was 25 watts, and the air was cooled from the blower 6 to the entire surface of the power generation unit of PEFC 1 at a wind speed of 3.0 m / sec, and the temperature of the power generation unit was set to 100 ° C. When the amount of heat released from PEFC 1 at this time was measured, the amount of heat released by conduction heat transfer was 0.2 watts, the amount of heat released by convection heat transfer was 24.0 watts, and the amount of heat released by radiant heat transfer was 0.00. It was 8 watts. At this time, the maximum temperature of the electrolytic capacitor 2 was 78 ° C., which was lower than the heat resistance temperature.
(Example 5)
A small SOFC unit having the same configuration as that of FIG. 1 in which an SOFC instead of PEFC was provided as a heat generating component was produced. That is, the SOFC unit is configured by housing the SOFC 1 as a heat generating component and the electrolytic capacitor 2 as a low heat resistant component in a housing 10. The power generating section of SOFC 1 that generates heat in this SOFC unit has dimensions of 100 mm long × 100 mm wide × 30 mm high, has a volume of 300 cc, and has a surface area of 320 cm ² . And the aluminum foil is affixed on the whole power generation part surface of SOFC1 with the adhesive agent. The emissivity of the surface of the power generation section of SOFC1 with respect to infrared rays having a wavelength of around 10 micrometers was 0.04 as measured by a radiation thermometer. The SOFC 1 is disposed on the bottom surface of the housing 10 via a silica heat insulating spacer 5, and this spacer 5 has a thermal conductivity of 0.1 watt / mK and a size of 5 mm in length × 5 mm in width. X Height is 3 mm.

With this configuration, the heat generation amount from the SOFC 1 was 150 watts, and the air was cooled from the blower 6 to the entire surface of the power generation unit of the SOFC 1 at a wind speed of 0.4 m / sec, and the temperature of the power generation unit was set to 500 ° C. When the amount of heat released from the SOFC 1 at this time was measured, the amount of heat released by conduction heat transfer was 1.7 watts, the amount of heat released by convection heat transfer was 124.4 watts, and the amount of heat released by radiant heat transfer was 23. It was 9 watts. And the maximum temperature of the electrolytic capacitor 2 at this time was 85 degreeC, and was below the heat-resistant temperature.
(Comparative example)
Instead of the stainless steel plate of Example 1 whose surface was polished, a 0.05 mm thick stainless steel plate was placed on the surface of the power generation unit of PEFC1, and the emissivity of the power generation unit surface was set to 0.95. A notebook computer having the same configuration as in Example 1 was prepared except for the above. In the same manner as in Example 1, the amount of heat released during the power generation operation of PEFC 1 was measured.

    With this configuration, the amount of heat generated from PEFC 1 was 25 watts, and air was sent from the blower 6 to the entire surface of the power generation unit of PEFC 1 at a wind speed of 1.5 m / second to perform air cooling, and the temperature of the power generation unit was 100 ° C. When the amount of heat released from PEFC 1 at this time was measured, the amount of heat released by conduction heat transfer was 0.2 watts, the amount of heat released by convection heat transfer was 17.1 watts, and the amount of heat released by radiant heat transfer was 7. It was 7 watts. At this time, the maximum temperature of the electrolytic capacitor 2 was 95 ° C., which was 10 ° C. higher than the heat resistance temperature.

    As shown in Examples 1 to 5 and Comparative Example above, heat transfer to the low heat resistant component can be suppressed by setting the emissivity of the surface of the heat generating component to 0.04 or more and 0.3 or less. Therefore, it has been clarified that the temperature rise in the low heat resistant component can be suppressed.

  The electronic device according to the present invention has an effect of suppressing heat dissipation from the heat-generating component to the low heat-resistant component. For example, the heat-generating component is a power-generating component, and particularly effective for an electronic device equipped with a fuel cell as the power-generating component. It is. In particular, the present invention is more useful in electronic devices such as miniaturized and thin portable devices in which a heat generating component and a low heat resistant component are arranged close to each other.

Sectional drawing which shows schematically the structure of the electronic device which concerns on embodiment of this invention

Explanation of symbols

1 PEFC
2 Electrolytic Capacitor 3 Storage Disk 4 Lithium Ion Secondary Battery 5 Spacer 6 Blower 10 Housing 11 First Board 12 Second Board 13 Air Outlet 14 Air Inlet

Claims (17)

In an electronic device having a built-in heat-generating component composed of a power supply unit and a low heat-resistant component whose maximum operating temperature is lower than the operating temperature of the heat-generating component,
At least a part of the surface of the heat generating component has an emissivity of 0.04 or more and 0.3 or less with respect to infrared rays having a wavelength of around 10 micrometers.   The electronic device according to claim 1, wherein the emissivity is 0.04 or more and 0.1 or less.   The electronic device according to claim 1, wherein the heat generating component is a power supply module.   The electronic device according to claim 1, wherein the heat generating component is a power generating component.   The electronic device according to claim 4, wherein the power generation component is a fuel cell.   The electronic device according to claim 5, wherein the fuel cell is a polymer electrolyte fuel cell.   The electronic device according to claim 5, wherein the fuel cell is a solid oxide fuel cell.   The electronic apparatus according to claim 1, wherein the low heat-resistant component is any one of an electrolytic capacitor, a crystal device, an image sensor, an IC card, a battery, and a storage disk.   The heat generating component and the low heat resistant component are arranged inside a housing, and the heat transfer from the heat generated by the heat generating component through the housing can be suppressed. The electronic device according to Crab.   The electronic device according to claim 9, wherein the casing and the heat generating component are thermally insulated.   The electronic device according to claim 10, wherein the casing is made of a heat insulating material.   The electronic device according to claim 10, wherein a heat insulating material is disposed between the housing and the heat generating component.   The electronic device according to claim 1, wherein the heat generating component and the low heat resistant component are disposed inside a housing, and includes a cooling unit that cools the heat generating component by convective heat transfer. The housing has an air outlet for discharging internal air to the outside, and an air inlet for taking external air into the inside,
The electronic device according to claim 13, wherein the cooling means is a blower.   The electronic device according to claim 1, wherein at least a part of the surface of the heat-generating component is formed of a flat metal surface.   The electronic device according to claim 15, wherein the metal surface is made of a metal oxide. The electronic device according to claim 16, wherein the metal oxide is magnesium oxide or aluminum oxide.

Images