Thermal conductivity measurement device and thermal conductivity measurement method

A thermal conductivity measurement device comprises: first and second clamping members which clamp an object; a heating member which has a contacting end surface which contacts a distal end surface of the first clamping member through a first axial correction member, and a distal end surface on the reverse side of the contacting end surface; a cooling member which has a contacting end surface which contacts a distal end surface of the second clamping member through a second axial correction member, and a distal end surface on the reverse side of the contacting end surface; a plurality of temperature sensors disposed on the clamping members; and a mechanism which applies a pressing force between the heating member and the cooling member. At least one surface of the first axial correction member and the second axial correction member has a convex curved shape, and the other surface is a flat surface.

TECHNICAL FIELD

The present invention relates to a thermal conductivity measurement apparatus and a thermal conductivity measurement method for measuring thermal conductivity of a material.

BACKGROUND ART

Various apparatuses are conventionally known as an apparatus measuring a thermophysical property value (particularly thermal conductivity) of an object to be measured such as a resin material and a metallic material and a contact thermal resistance between members of a resin material or a metallic material by a steady state method (Patent Documents 1 to 5).

A thermophysical property measurement apparatus using a steady state method employs a configuration in which an object to be measured is sandwiched between a heating-side holding member connected to a heating part and a cooling-side holding member connected to a cooling part. The heating-side holding member and the cooling-side holding member are configured such that temperature can be measured at multiple positions, and a measured temperature gradient is used for obtaining a thermophysical property value (such as thermal conductivity) of an object to be measured and a contact thermal resistance between the members.

PRIOR ART DOCUMENTS

Patent Documents

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

A thermophysical property (thermal conductivity, contact thermal resistance, etc.) measurement apparatus using a steady state method maintains a state in which an object to be measured is sandwiched between a heating-side holding member provided with multiple temperature measurement mechanisms and a cooling-side holding member provided with multiple temperature measuring mechanisms and allows heat to pass from the heating-side holding member connected to a heat source through the object to be measured to the cooling-side holding member connected to a cooling source in one direction so as to calculate a thermophysical property (such as thermal conductivity) of the object to be measured from temperature measured at temperature measurement points disposed in both holding members. When the contact thermal resistance is calculated between the members, the heating-side holding member and the cooling-side holding member are brought into contact with each other while a pressing force is applied without sandwiching the object to be measured, and the contact thermal resistance is calculated from the temperature measured at the temperature measurement points disposed in both holding members.

To ensure the measurement accuracy of the thermophysical property value of the object to be measured, a flow of heat passing through the heating-side holding member, the object to be measured, and the cooling-side holding member in this order must be prevented from being spatially biased.

In the measurement apparatus described above, by disposing the object to be measured in a normal state between the heating-side holding member and the cooling-side holding member, i.e., by disposing the object such that the heating-side holding member, the object to be measured, and the cooling-side holding member are vertically arranged along a heat passage direction (vertical direction), the heat can pass through the heating-side holding member, the object to be measured, and the cooling-side holding member without bias of the flow of heat.

On the other hand, if the object to be measured is disposed in a non-normal disposition state between the heating-side holding member and the cooling-side holding member, i.e., if the heating-side holding member, the object to be measured, and the cooling-side holding member are tilted from the heat passage direction (vertical direction), the flow of passing heat is spatially biased and, as a result, the thermophysical property value of the object to be measured cannot precisely be measured.

To detect an abnormality of disposition of the heating-side holding member, the object to be measured, and the cooling-side holding member, for example, Patent Document 1 discloses a system that is provided with a mechanism capable of measuring a temperature variation in an in-plane direction of the holding members in a direction parallel to surfaces of the heating-side holding member and the cooling-side holding member coming into contact with the object to be measured and that detects the temperature variation in the in-plane direction equal to or greater than a certain value as an abnormality of disposition.

However, adding the system detecting an abnormality of disposition of the heating-side holding member, the object to be measured, and the cooling-side holding member makes the apparatus more complicated and increases costs. Additionally, since an operation must be performed with sufficient attention given to a disposition state and an abnormality cannot be detected unless measurement is started, the measurement takes time depending on the disposition state, resulting in deterioration in efficiency of the measurement. Another problem is that the thermophysical property value of the object to be measured cannot precisely be measured due to a set threshold value of the temperature variation in some cases.

An object of the present invention is to provide a thermal conductivity measuring apparatus capable of shortening a setting time and an adjustment time of measurement and efficient and highly accurate in measurement.

Means for Solving Problem

An aspect of the present invention provides

a thermal conductivity measurement device comprising:

a first holding member including a contact end face coming into contact with an object to be measured and a distal end face disposed on the side opposite to the contact end face;

a second holding member including a contact end face coming into contact with the object to be measured and a distal end face disposed on the side opposite to the contact end face, the second holding member holding the object to be measured together with the first holding member;

a heating member including an abutting end face that abuts on the distal end face of the first holding member across a first axis correction member including two opposite faces and a distal end face disposed on the side opposite to the abutting end face, the heating member heating the first holding member;

a cooling member including an abutting end face that abuts on the distal end face of the second holding member across a second axis correction member including two opposite faces and a distal end face disposed on the side opposite to the abutting end face, the cooling member cooling the second holding member;

a plurality of temperature sensors disposed in the first holding member and the second holding member; and

a pressing force applying mechanism applying a pressing force between the heating member and the cooling member wherein

at least one face of the first axis correction member and the second axis correction member is a curved face having a convex curved shape, while the other face is a flat face that is flat.

Another aspect of the present invention provides

a thermal conductivity measurement device comprising:

a first holding member including a contact end face coming into contact with an object to be measured and a distal end face disposed on the side opposite to the contact end face;

a second holding member including a contact end face coming into contact with the object to be measured and a distal end face disposed on the side opposite to the contact end face, the second holding member holding the object to be measured together with the first holding member;

a heating member including an abutting end face that faces the distal end face of the first holding member and heating the first holding member;

a cooling member including an abutting end face that faces the distal end face of the second holding member and cooling the second holding member;

an axis correction member sandwiched at least between the distal end face of the first holding member and the abutting end face of the heating member or between the distal end face of the second holding member and the abutting end face of the cooling member and including two faces facing the distal end face and the abutting end face; and

a plurality of temperature sensors disposed in the first holding member and the second holding member, wherein

at least one face of the axis correction member is a curved face having a convex curved shape.

Another aspect of the present invention provides

a thermal conductivity measurement device comprising:

a first holding member including a contact end face coming into contact with an object to be measured and a distal end face disposed on the side opposite to the contact end face;

a second holding member including a contact end face coming into contact with the object to be measured and a distal end face disposed on the side opposite to the contact end face, the second holding member holding the object to be measured together with the first holding member;

a heating member including an abutting end face that faces the distal end face of the first holding member and heating the first holding member;

a cooling member including an abutting end face that faces the distal end face of the second holding member and cooling the second holding member;

an axis correction member sandwiched at least between the distal end face of the first holding member and the abutting end face of the heating member or between the distal end face of the second holding member and the abutting end face of the cooling member and including two faces facing the distal end face and the abutting end face; and

a plurality of temperature sensors disposed in the first holding member and the second holding member, wherein

at least one face of the axis correction member is a curved face having a convex curved shape, while the other face is a flat face that is flat.

Another aspect of the present invention provides

a thermal conductivity measurement method comprising the steps of:

preparing the thermal conductivity measurement device;

sandwiching the object to be measured between the first holding member and the second holding member;

applying a pressing force between the heating member and the cooling member by the pressing force applying mechanism;

heating the first holding member with the heating member and cooling the second holding member with the cooling member; and

measuring temperatures of the first holding member and the second holding member with the temperature sensors to detect the thermal conductivity of the object to be measured.

According to the present invention, since the first axis correction member and the second axis correction member are respectively sandwiched between the first holding member and the heating member and between the second holding member and the cooling member, and the first axis correction member and the second axis correction member have at least one face that is a curved face having a convex curved shape and the other face that is a flat surface, the axes of the three members, i.e., the heating-side holding member, the object to be measured, and the cooling-side holding member, can be made coincident with each other simply by applying the pressing force without special adjustment, so that the temperature variation can significantly be suppressed in the in-plane direction of the object to be measured. Therefore, the setting time and the adjustment time of the measurement can be shortened, and the efficient and highly-accurate measurement can be performed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

FIG. 1is a configuration diagram of a thermal conductivity measurement device according to a first embodiment of the present invention, generally denoted by100. In a thermal conductivity measurement device100, a heating-side holding member7and a cooling-side holding member9holding an object to be measured8are sandwiched between a heating block unit5and a cooling block unit6so that a pressing force can be applied by a pressing force adjusting screw14.

The heating-side holding member7and the cooling-side holding member9are configured to have the same shape by using the same material and are formed into a three-dimensional shape, for example, a rectangular columnar shape or a circular columnar shape, having a contact end face coming into contact with the object to be measured8and a distal end face opposite to the contact end face. The contact end face and the distal end face are flat surfaces parallel to each other. A material having relatively high thermal conductivity, for example, copper or aluminum is used as the material, so that a thermophysical property of the object to be measured8can accurately be measured. Other usable materials include aluminum alloy, stainless steel, etc.

The heating block unit5is made of a material having relatively high thermal conductivity, for example, copper or aluminum, and is made up of a metal block having an abutting end face abutting on the distal end face of the heating-side holding member7via a heating-side axis correction member51, a heating element, for example, a ceramic heater or a cartridge heater, etc. The metal block has a function of diffusing heat to make temperature uniform, and a thermal conductive grease for reducing a contact thermal resistance is applied to a joint position with the heating element as needed. The heating element is connected to a heating block unit control device18for controlling an amount of heat generation.

The cooling block unit6is made of a material having relatively high thermal conductivity, for example, copper or aluminum, and has a metal block having an abutting end face abutting on the distal end face of the cooling-side holding member9via a cooling-side axis correction member52, a cooing element, for example, a water cooling unit, a Peltier element, or a combination of a heat sink and a cooling fan, etc. The metal block has a function of diffusing heat to make temperature uniform, and a thermal conductive grease for reducing a contact thermal resistance is applied to a joint position with the cooling element as needed. The cooling element is connected to a cooling block unit control device19for controlling an amount of heat discharge.

The heating-side axis correction member51and the cooling-side axis correction member52are made of a material having relatively high thermal conductivity such as copper or aluminum so that the heat generated in the heating block unit can efficiently be conducted to the heating-side holding member. Additionally, the heat conducted through the heating-side holding member7and the object to be measured8to the cooling-side holding member9can efficiently be discharged via the cooling block unit6.

The thermal conductivity measurement device100according to the first embodiment of the present invention has the heating-side axis correction member51and the cooling-side axis correction member52having a flat plate shape and sandwiched and held between the heating-side holding member7and the heating block unit5and between the cooling-side holding member9and the cooling block unit6, respectively. The heating-side axis correction member51and the cooling-side axis correction member52may be removable.

The heating-side axis correction member51has an end face having a planar R shape (convex cylindrical face) or a spherical R shape (convex spherical face) on the heating block unit5side. Similarly, the cooling side shaft correction member52has an end face having a planar R shape or a spherical R shape on the cooling block unit6side. The surfaces facing the planar R shape or the spherical R shape are preferably relatively flat as compared to the R face, and this enables more accurate measurement.

Preferably, the heating-side axis correction member51covers the entire distal end face of the heating-side holding member7, and the vertex of the planar R shape is disposed on the central axis of the heating-side holding member7. The same applies to the cooling-side axis correction member52.

To reduce the contact thermal resistance, thermal conductive grease10is applied between the metal block of the heating block unit5and the heating-side axis correction member51and between the cooling-side axis correction member52and the metal block of the cooling block unit6.

In such a configuration, the heat generated by the heating block unit5is transferred through the heating-side axis correction member51to the heating-side holding member7, transferred through the object to be measured8to the cooling-side holding member9, and discharged through the cooling-side axis correction member52from the cooling block unit6. When the heat passes through in a constant direction in this way, a temperature gradient is formed according to the thermal conductivity of the members and a difference in the contact thermal resistance between the members.

The side faces of the heating-side holding member7and the cooling-side holding member9have multiple holes formed along the longitudinal direction. Thermocouples4are inserted in the holes as temperature sensors and fixed such that temperature measurement points coincide with axes of the heating-side holding member7and the cooling-side holding member9. These multiple thermocouples4enable measurement of temperature distribution corresponding to vertical positions. The measured values are input to a temperature measurement device3, so that the temperature can constantly be monitored. From these measured values, an amount of heat passing through the object to be measured8can be calculated so as to calculate the thermophysical property value of the object to be measured8and the contact thermal resistance between the members. Such an arithmetic function may be built into the temperature measurement device3or may be built into an external computer connected through a network.

The cooling block unit6is disposed at the center of a base17. Multiple (inFIG. 1, two) shafts15are disposed at end portions of the base17. A support plate12is disposed above the base17so as to be vertically displaceable while being guided by the shaft15. The heating block unit5is attached to the support plate12. An upper plate16is fixed to upper ends of the shafts15. By providing the multiple shafts15as described above, vertical alignment can be ensured among the heating block unit5, the heating-side axis correction member51, the heating-side holding member7, the object to be measured8, the cooling-side holding member9, the cooling-side axis correction member52, and the cooling block unit6.

The thermal conductivity measurement device100further includes a pressing force adjustment mechanism50for adjusting a pressing force applied to the object to be measured8via the heating-side holding member7and the cooling-side holding member9. The pressing force adjustment mechanism50is made up of the support plate12disposed on an upper portion of the heating block unit5and supporting the heating block unit5, a load cell11disposed on the support plate12for monitoring the pressing force, a spacer13disposed on the load cell11for transferring the pressing force to the load cell11, and the pressing force adjustment screw14fixed to the upper plate16for applying the pressing force via the spacer13to the load cell11. The pressing force measured by the load cell11is input to a measurement control device2so that the pressing force can constantly be monitored.

A method of adjusting a pressing force will be described. When the thermophysical property of the object to be measured8is measured, the heat applied from the heating block unit5passes through the heating-side axis correction member51, the heating-side holding member7, the object to be measured8, the cooling-side holding member9, and the cooling-side axis correction member52and reaches the cooling block unit6. Due to the passing heat, the temperature rises in the members, i.e., the heating block unit5, the heating-side axis correction member51, the heating-side holding member7, the object to be measured8, the cooling-side holding member9, the cooling-side axis correction member52, and the cooling block unit6. As the temperature rises in the members, the members expand, and the pressing force applied to the load cell11changes during measurement. Since the pressing force applied to the object to be measured8must be controlled to a constant force in the thermophysical property measurement of the object to be measured8, it is necessary to adjust the pressing force adjustment screw14depending on a displayed pressing force. It is noted that the thermophysical property of the object to be measured can accurately be measured when variations from a predetermined pressing force are within ±5%, or preferably, variations from a predetermined pressing force are within ±1%. Therefore, the “constant pressing force” of the present invention means the variations from a predetermined pressing force within the range of ±5%, more preferably ±1%. Thus, it is preferable to provide a pressing force control device adjusting the pressing force adjustment screw14through feedback of the pressing force applied to the load cell11so as to automatically control the pressing force to a predetermined constant value. This enables elimination of manual work and automation of measurement. The support plate12and the spacer13are desirably made of sufficiently rigid metal.

As shown in a thermal conductivity measurement device110ofFIG. 2, a heat insulating plate20may be disposed between the heating block unit5and the support plate12. This can reduce an amount of heat transferred from the heating block unit5to the support plate12to increase the amount of heat transferred to the object to be measured8.

When the thermophysical property of the object to be measured8is measured, thickness information of the object to be measured8is also important. As shown in a thermal conductivity measurement device210ofFIG. 3, a thickness display device21may be disposed that can measure and display a total thickness of the heating-side axis correction member51, the heating-side holding member7, the object to be measured8, the cooling-side holding member9, and the cooling-side axis correction member52in the measurement state. The thickness display device21is formed by using a laser range finder, an optical scale, a magnetic scale, etc. However, the device may be disposed at another position as long as the thickness of the object to be measured8can be calculated by using a position and a mechanism without using the position shown inFIG. 3. By preliminarily measuring the thickness of the heating-side holding member7, the cooling-side holding member9, the heating-side axis correction member51, and the cooling-side axis correction member52with slide calipers, a micrometer, etc., the thickness of the object to be measured8can more precisely be calculated from the thickness displayed on the thickness display device21.

The configurations ofFIGS. 2 and 3are also applicable to thermal conductivity measurement devices described in second to fifth embodiments.

The heating-side holding member7and the cooling-side holding member9are formed into a circular columnar shape having a diameter of 10 mm to 30 mm and a height of 30 to 100 mm, so that the thermophysical property value of the object to be measured8and the contact thermal resistance between the members can precisely and accurately be measured. The shapes of the heating-side holding member7and the cooling-side holding member9are not limited thereto, and the same effect can be obtained also from a shape of a rectangular column etc. The faces (contact end faces) of the heating-side holding member7and the cooling-side holding member9coming into contact with the object to be measured8are processed into flat faces, and the surface roughness of the processed faces preferably have smaller Ra. In experiments, the thermophysical property of the object to be measured8can precisely be measured when the faces are finished to a level of Ra=0.8. However, the surface roughness is not limited to this value.

The object to be measured8is inserted and fixed between the contact end faces of the heating-side holding member7and the cooling-side holding member9. When the object to be measured8is a fluid, the object is adjusted to a specified thickness by a dispenser and screen printing and is applied between the heating-side holding member7and the cooling-side holding member9. The heating-side holding member7and the cooling-side holding member9may be fixed by the viscosity force or the adhesion force of the object to be measured8itself or may be fixed by using an auxiliary member such as an adhesive tape.

To reduce heat dissipation due to heat transfer from the surfaces of the heating-side holding member7and the cooling-side holding member9to the air, a heat insulating material may be wrapped around the holding members7,9. When the thermophysical property of the object to be measured8is measured, the heating-side holding member7and the cooling-side holding member9with the object to be measured8sandwiched therebetween are integrally disposed on the cooling block unit6via the cooling-side axis correction member52, and the heating block unit5is then disposed thereon via the heating-side axis correction member51.

In this case, even if the pressing force adjustment screw14of the pressing force adjustment mechanism is not tightened, a pressing force is applied due to the weight of the members, particularly, the heating block unit5. It is noted that tightening the pressing force adjusting screw14of the pressing force adjusting mechanism is more preferable. As a result, a constant pressing force is applied to the heating-side axis correction member51, the heating-side holding member7, the object to be measured8, the cooling-side holding member9, and the cooling-side axis correction member52, and the measurement of the thermophysical property is started in this state.

InFIG. 1, the thermal conductive grease10is applied between the metal block of the heating block unit5and the heating-side axis correction member51and between the metal block of the cooling block unit6and the cooling-side axis correction member52; however, the thermal conductive grease may also be applied between the heating-side axis correction member51and the heating-side holding member7and between the cooling-side holding member9and the cooling-side axis correction member52.

As described above, the distal end face of the heating-side axis correction member51in contact with the heating block unit5and the distal end face of the cooling-side axis correction member52in contact with the cooling block unit6have a planar R shape or a spherical R shape; however, only one of the heating-side axis correction member51and the cooling-side axis correction member52may have a planar R shape or a spherical R shape. The other end faces such as the contact end faces for contact between the shaft correction members51,52and the holding members7,9have a planar shape.

In a conventional structure, the heating-side axis correction member51and the cooling-side axis correction member52are not included, and the distal end faces of the holding members7,9are flat. Therefore, to precisely measure the thermophysical property of the object to be measured8, when heat passes through the heating-side holding member7, the object to be measured8, and the cooling-side holding member9, the temperature distribution in an in-plane direction (a plane perpendicular to axes) of the heating-side holding member7and the cooling-side holding member9must allow the heat to pass through symmetrically about the axial center without bias as shown in an isotherm graph ofFIG. 5so that a temperature variation in the plane is made as small as possible. In this graph, reference numeral25denotes a temperature measurement point of the thermocouple4, and reference numeral26denotes an isotherm of a specific temperature.

To allow the heat to pass from the heating block unit5through the axial centers of the heating-side holding member7, the object to be measured8, the cooling-side holding member9, and the cooling block unit6, it is necessary to dispose the heating-side holding member7, the object to be measured8, and the cooling-side holding member9such that the axes of these three members coincide with each other, i.e., such that the axial centers of the heating-side holding member7and the cooling-side holding member9as well as the center axis of the object to be measured8are on a straight line.

However, as compared to the heating block unit5and the cooling block unit6, the heating-side holding member7and the cooling-side holding member9are small, and therefore, when a pressing force is applied by adjusting the pressing force adjustment screw14to the members, i.e., the heating-side holding member7, the object to be measured8, and the cooling-side holding member9, a deviation may occur among the axes of the three members, i.e., the heating-side holding member7, the object to be measured8, and the cooling-side holding member9. Actually, considering the parallelism and flatness of the abutting end face of the heating member and the abutting end face of the cooling member manufactured by machining, surface treatment, etc., the axes of the three members, i.e., the heating-side holding member7, the object to be measured8, and the cooling-side holding member9, are not on a straight line and are usually deviated to no small extent although magnitude may differ.

FIG. 4shows an example thereof in which the parallelism of the metal block of the heating block unit5is not achieved, i.e., the case that the lower surface of the metal block is not horizontal. If a pressing force is applied when the parallelism of the metal block of the heating block unit5is not achieved, the distal end face of the heating-side holding member7follows the abutting end face of the metal block without the parallelism achieved, so that the abutting end face of the heating-side holding member7comes into partial contact with the object to be measured8.

When the abutting end face of the heating-side holding member7comes into partial contact with the object to be measured8as shown inFIG. 4, a thermal flux passing through the heating-side holding member7, the object to be measured8, and the cooling-side holding member9is not symmetric about the axial center and is biased toward one side as indicated by arrows55. Consequently, as shown inFIG. 6, the heat passes through the heating-side holding member7, the object to be measured8, and the cooling-side holding member9while being biased from the center, which makes the temperature variation larger in the in-plane direction of the object to be measured8, so that the thermophysical property of the object to be measured8cannot precisely be measured. Therefore, to precisely measure the thermophysical property of the object to be measured8, it is necessary to perform confirmation and adjustment so that the parallelism is achieved in each of the heating block unit5coming into contact with the heating-side holding member7and the cooling block unit6coming into contact with the cooling-side holding member9. In this case, skillful work is required, which makes a setting time and an adjustment time for measurement longer.

Alternatively, it is conceivable that a unit measuring a thermal bias in the members is added to make a correction corresponding to the measured thermal bias through calculation without the adjustment work. In this case, complicated calculations are required, and the measurement accuracy may be reduced.

FIG. 7shows an example in which the present invention is applied when the parallelism of the abutting end face of the metal block of the heating block unit5is not achieved. As shown inFIG. 7(a), since the parallelism of the abutting end face of the heating block unit5is not achieved in the initial stage of application of the pressing force, the heating-side holding member7is tilted, coming into partial contact with the object to be measured8. In this case, the heat flux passing through the heating-side holding member7, the object to be measured8, and the cooling-side holding member9is biased and the temperature variation in the in-plane direction of the object to be measured8is large, so that the thermophysical property of the object to be measured8cannot precisely be measured.

However, in the thermal conductivity measurement device100, the distal end faces of the heating-side holding member7and the cooling-side holding member9are provided with the heating-side axis correction member51and the cooling-side axis correction member52having a planar R shape (convex cylindrical face) or a spherical R shape (convex spherical face) facing toward the block units5,6. Therefore, when the heating-side holding member7and the cooling-side holding member9sandwiching the object to be measured8are sandwiched between the cooling block unit6and the heating block unit5via the heating-side axis correction member51and the cooling-side axis correction member52, respectively, and a pressing force is applied by the pressing force adjustment screw14, the heating-side axis correction member51and the cooling-side axis correction member52having the planar R shape or the spherical R shape attempt to achieve a stable posture as shown inFIG. 7(b), so that a motion following the surface of the heating block unit5naturally occurs. Reference numeral27denotes a pressing force vector applied from the pressing force adjustment screw14. Reference numeral28denotes a horizontal pressing force vector acting on the curved surface of the heating-side axis correction member51when the pressing force is applied.

Because of this motion, as shown inFIG. 7(c), the axes of the three members, i.e., the heating-side holding member7, the object to be measured8, and the cooling-side holding member9, can be made coincident with each other simply by applying the pressing force by the pressing force adjustment screw14without special adjustment, and the heat can pass axially symmetrically through the heating-side holding member7, the object to be measured8, and the cooling-side holding member9(seeFIG. 5), so that the temperature variation can significantly be reduced in the in-plane direction of the object to be measured8. As a result, the thermophysical property of the object to be measured8can precisely be measured simply by applying the pressing force without special adjustment.

In this embodiment, the heating-side axis correction member51and the cooling-side axis correction member52are provided with the curved surfaces having the planar R shape (convex cylindrical face) or the spherical R shape (convex spherical face) facing toward the block units5,6so as to minimize the frictional force acting when the members attempt to be in a stable posture during application of the pressing force, and to maximize the pressing force vector generated due to the pressing force.

To ensure higher measurement accuracy, it is desirable to increase the amount of heat passing through the heating-side holding member7, the object to be measured8, and the cooling-side holding member9to make the measurement temperature at the thermocouples higher, i.e., to make the temperature gradient greater. This is because the influence of the measurement temperature variation in the thermocouples (e.g., ±1.5° C. in the case of K thermocouples, Class1) can be suppressed by increasing the amount of passing heat to make the measurement temperature at the thermocouples higher. If the amount of passing heat is small and the temperature gradient is small, this measurement temperature variation considerably affects the thermophysical property of the object to be measured.

If the thickness of the thermal conductive grease10is thick, the thermal resistance of the thermal conductive grease becomes large, and therefore, preferably, the thermal conductive grease10is thinly applied.

In experiments, the heating-side holding member7and the cooling-side holding member9were shaped into a rectangular column having a cross section of 40 mm×40 mm and a height of 50 mm, and the heating-side axis correction member51and the cooling-side axis correction member52having a spherical 81050 shape (a convex shape with a radius R of 1050 mm) were respectively disposed on the distal end faces of the heating-side holding member7and the cooling-side holding member9. As a result, the thermophysical property values of the object to be measured8and the contact thermal resistance between the members were precisely measurable.

Regarding the size of the radius R, a difference between a height of a central portion of R and a height of a peripheral portion must be at least larger than the flatness of the object to be measured8. However, if the difference of the height is too large, the contact of the heating-side axis correction member51and the cooling-side axis correction member52with the block units5,6is brought into a state close to point contact, so that heat flows passing through the holding members7,9are not parallel. Therefore, preferably, the difference between the height of the central portion of R and the height of the peripheral portion is ten times or less, preferably several times or less, with respect to a particle diameter of a filler contained in the thermal conductive grease10. As a result, the heat flows passing through the holding members7,9become substantially parallel, and the measurement accuracy can be increased.

FIG. 8shows a state of contact between the heating-side holding member7and the object to be measured8in the case of using the heating-side holding member7and the cooling-side holding member9having the cross section of 40 mm×40 mm and the height of 50 mm in the thermal conductivity measurement device100ofFIG. 7.FIG. 8(a)andFIG. 8(b)show the case of not disposing and the case of disposing, respectively, the heating-side axis correction member51and the cooling-side axis correction member52on distal end portions. A dark color portion indicates a contact portion, and a color strength indicates a contact strength. InFIG. 8(a), an upper portion has a dark black color, and it can be seen that a strong partial contact is occurring in the upper portion. In contrast, inFIG. 8(b), the whole area has a light black color, and it can be seen that the whole area is making uniform contact.

Although the object to be measured8is sandwiched between the heating-side holding member7and the cooling-side holding member9to measure the thermophysical property value of the object to be measured8is measured in the above description, additionally, the present invention produces a great effect also in measurement in a state without sandwiching the object to be measured8. Specifically, this is the case that the pressing force and the contact thermal resistance between the members are calculated by using only the heating-side holding member7and the cooling-side holding member9without sandwiching the object to be measured8. When the contact thermal resistance is calculated, a state of contact between the heating-side holding member7and the cooling-side holding member9significantly affects a measurement result. By disposing the heating-side axis correction member51and the cooling-side axis correction member52on the distal end faces of the heating-side holding member7and the cooling-side holding member9as in the present invention, as shown inFIG. 8, an ideal contact state is acquired such that both members come into uniform contact without special adjustment. By measuring the contact thermal resistance in this state, the contact thermal resistance can efficiently and accurately be measured.

The thermal conductive grease10has a certain thickness defined by a filler contained therein and a thermal conductivity of about several W/mK and therefore has a certain level of thermal resistance. However, since the heat flux is calculated in terms of the amount of heat passing through the object to be measured by using the multiple thermocouples shown in the figures in this thermal conductivity measurement method, no influence of the thermal conductive grease10appears in the measurement object. Therefore, highly accurate measurement can be performed.

Specifically, the thermal conductivity measurement is calculated from a difference in temperature of the top and bottom of the object to be measured8estimated from the measured temperatures of the thermocouples4attached to the heating-side holding member7and the cooling-side holding member9as well as an amount of passing heat that can be estimated from the measured temperatures of the multiple thermocouples4attached to one or both of the heating-side holding member7and the cooling-side holding member9. First, regarding the temperature of the top and bottom of the object to be measured8, when the relationship between the distance from the surface of the object to be measured8and the temperature is shown in a graph from the measured temperatures of the thermocouples4attached at regular intervals to the heating-side holding member7, temperatures of measurement points are in a relationship proportional to the distance from the surface of the object to be measured8. Therefore, the surface temperature of the object to be measured8can easily be calculated from the temperatures of the measurement points and the distance from the surface of the object to be measured8. The same applies to the cooling-side holding member9side. From the difference between these temperatures, the difference in temperature of the top and bottom of the object to be measured8is obtained.

Regarding the amount of passing heat, for example, when a measured temperature difference LT of the thermocouples4disposed in the heating-side holding member7, a distance L between the thermocouples4, a cross-sectional area A of the heating-side holding member7, and a thermal conductivity A of the heating-side holding member7are known, the amount of passing heat is easily obtained from Formula 1 below:
ΔT×L/A/λ  (1).
Therefore, the thermal conductive grease10attached to the heating-side holding member7and the cooling-side holding member9on the side opposite to the object to be measured8does not affect the measurement result.

Although the heating-side axis correction member51and the cooling-side axis correction member52are respectively sandwiched between the heating block unit5and the heating-side holding member7and between the cooling block unit6and the cooling-side holding member9in the specific example described in the first embodiment of the present invention, either one may be included.

However, even if the machining accuracy of the holding members7,9is low on the end faces facing toward the object to be measured8and the two end faces are not exactly parallel planes, the influence of the machining accuracy can be absorbed by disposing the axis correction members51,52on both members to obtain the high measurement accuracy. Additionally, when the thermal resistance of a plurality of members integrated by swaging etc., this effect is further exerted. Even if machining accuracy is high in respective members before integration, a tilt is caused in the integrated members in various levels depending on a relationship of tolerance and a placement state of the members at the time of integration, a device used, etc. Therefore, if it is attempted to directly measure the integrated members, the partial contact occurs, so that the thermophysical property of the members cannot accurately be measured. By disposing the heating-side axis correction member51and the cooling-side axis correction member52on the distal end faces of the heating-side holding member7and the cooling-side holding member9as in the present invention, the partial contact can be prevented, and the measurement accuracy can be increased even in the integrated members.

Although the first embodiment of the present invention has been described with a specific example used for measurement of thermal conductivity, the present invention can obviously be used for measurement of thermal resistance.

Second Embodiment

FIG. 9is a configuration diagram of a thermal conductivity measurement device according to the second embodiment of the present invention, generally denoted by200. InFIG. 9, the same reference numerals asFIG. 2denote the same or corresponding portions.

The thermal conductivity measurement device200includes a heating-side axis correction member33and a cooling-side axis correction member34instead of the heating-side axis correction member51and the cooling-side axis correction member52, respectively, of the thermal conductivity measurement device110according to the first embodiment. The other structure is the same as the thermal conductivity measurement device110.

The heating-side axis correction member33and the cooling-side axis correction member34provides a planar shape for the distal end faces of the heating-side holding member7and the cooling-side holding member9, while providing a planar R shape (a convex cylindrical surface) or a spherical R shape (a convex spherical surface) for the abutting end faces of the heating block unit5and the cooling block unit6, thereby suppressing the temperature variation in the in-plane direction of the object to be measured8. In this case, the heating-side axis correction member33and the heating block unit5as well as the cooling-side axis correction member34and the cooling block unit6are fixed by a viscosity force or an adhesion force of grease or fixed by using an auxiliary member such as an adhesive tape.

In the thermal conductivity measurement device200according to the second embodiment of the present invention, due to the R shapes formed on the axis correction members33,34, when the heating-side holding member7, the object to be measured8, the cooling-side holding member9sandwiching the object to be measured8are placed on the cooling block unit6and a pressing force is applied via the heating block unit5by the pressing force adjustment screw14, the axes of the three members, i.e., the heating-side holding member7, the object to be measured8, and the cooling-side holding member9, can be made coincident with each other simply by applying the pressing force by the pressing force adjustment screw14without special adjustment, and the heat passes through the axial centers of the heating-side holding member7, the object to be measured8, and the cooling-side holding member9, so that the thermophysical property of the object to be measured8can precisely be measured.

Regarding the size of the radius R of the heating-side axis correction member33and the cooling-side axis correction member34, as in the first embodiment, a difference between the height of the central portion of R and the height of the peripheral portion must be at least larger than the flatness of the object to be measured8. However, if the difference of the height is too large, the contact between the heating-side axis correction member33and the heating-side holding member7and between the cooling-side axis correction member34and the cooling-side holding member9is brought into a state close to point contact, so that heat flows passing through the holding members7,9are not parallel. Therefore, preferably, the difference between the height of the central portion of R and the height of the peripheral portion is ten times or less, preferably several times or less, with respect to a particle diameter of a filler contained in the thermal conductive grease10. As a result, the heat flows passing through the holding members7,9become substantially parallel, and the measurement accuracy can be increased.

Although the distal end faces of the axis correction members33,34are flat inFIG. 9, the distal end faces may have a planar R shape or a spherical R shape. By using the axis correction members33,34having the distal end faces formed into the planar R shape and the spherical R shape, the measurement accuracy can be increased.

Third Embodiment

FIG. 10is a configuration diagram of a thermal conductivity measurement device according to the third embodiment of the present invention, generally denoted by300. InFIG. 10, the same reference numerals asFIG. 2denote the same or corresponding portions.

The thermal conductivity measurement device300includes a heating-side axis correction member151and a cooling-side axis correction member152instead of the heating-side axis correction member51and the cooling-side axis correction member52, respectively, of the thermal conductivity measurement device110according to the first embodiment. The other structure is the same as the thermal conductivity measurement device110.

As shown inFIG. 10, the heating-side axis correction member151has a structure in which convex protruding portions155in contact with the side surface of the heating-side holding member7are included on both sides of the heating-side axis correction member51of the first embodiment. Similarly, the cooling-side axis correction member152has a structure in which convex protruding portions155in contact with side surface of the cooling-side holding member9are included on both sides of the cooling-side axis correction member52.

Since the heating-side axis correction member151and the cooling-side axis correction member152have the protruding portions155,156as described above, a positional deviation of a placement location can be prevented when the object to be measured8sandwiched between the holding members7,9is placed in the thermal conductivity measurement device300. As a result, a placement time can be shortened, and measurement can be performed with high accuracy.

Although the heating-side axis correction member151and the cooling-side axis correction member152each have a pair of (two) protruding portions on both sides inFIG. 10, the number and shape of the protruding portions are not limited thereto.FIG. 11is a plan view of the heating-side axis correction member151used when the heating-side holding member7is a rectangular column as viewed from the heating-side holding member7side. A portion indicated by hatched lines is the protruding portion155, and the protruding portion155is disposed to surround the distal end portion of the heating-side holding member7.

FIG. 12is a plan view of another heating-side axis correction member151used when the heating-side holding member7is a rectangular column as viewed from the heating-side holding member7side. The portions indicated by hatched lines are the protruding portions155, and the protruding portions155are disposed to sandwich both sides of the heating-side holding member7.

AlthoughFIGS. 11 and 12show the heating-side axis correction member151disposed on the heating-side holding member7side, the cooling-side axis correction member152disposed on the cooling-side holding member9side may have the same shape.

The third embodiment has been described with a specific example in the case that the object to be measured8is sandwiched between the heating-side holding member7and the cooling-side holding member9to measure the thermophysical property of the object to be measured; however, even in the case of measurement of the contact thermal resistance between the members etc. without sandwiching the object to be measured8, a setting step can be facilitated by including such protruding portions. Although a specific example used for measurement of thermal conductivity has been described, the present invention can obviously be used for measurement of thermal resistance.

Fourth Embodiment

FIG. 13is a configuration diagram of a thermal conductivity measurement device according to the fourth embodiment of the present invention, generally denoted by400. InFIG. 13, the same reference numerals asFIG. 9denote the same or corresponding portions.

The thermal conductivity measurement device400includes a heating-side axis correction member133and a cooling-side axis correction member134instead of the heating-side axis correction member33and the cooling-side axis correction member34, respectively, of the thermal conductivity measurement device200according to the second embodiment. The other structure is the same as the thermal conductivity measurement device200.

Since the heating-side axis correction member133and the cooling-side axis correction member134have protruding portions135,136as described above, a positional deviation can be prevented when the object to be measured8sandwiched between the holding members7,9is placed in the thermal conductivity measurement device400. As a result, a placement time can be shortened, and measurement can be performed with high accuracy.

The shapes of the protruding portions135,136may be other shapes as described in the third embodiment (e.g.,FIGS. 11 and 12).

Fifth Embodiment

FIGS. 14 and 15are configuration diagrams of thermal conductivity measurement devices according to the fifth embodiment of the present invention, generally denoted by500,550, which are modifications of the thermal conductivity measurement device110according to the first embodiment shown inFIG. 2. InFIGS. 14 and 15, the same reference numerals asFIG. 2denote the same or corresponding portions.

While the thermal conductivity measurement device110includes the heating-side axis correction member51and the cooling side cooling member52respectively disposed both between the heating block unit5and the heating-side holding member7and between the cooling block unit6and the cooling-side holding member9, the thermal conductivity measurement devices500,550according to the fifth embodiment of the present invention each include either of the members.

FIGS. 16 and 17are configuration diagrams of other thermal conductivity measurement devices according to the fifth embodiment of the present invention, generally denoted by600,650, which are modifications of the thermal conductivity measurement device200according to the second embodiment shown inFIG. 9. InFIGS. 16 and 17, the same reference numerals asFIG. 9denote the same or corresponding portions.

While the thermal conductivity measurement device200includes the heating-side axis correction member33and the cooling side cooling member34respectively disposed both between the heating block unit5and the heating-side holding member7and between the cooling block unit6and the cooling-side holding member9, the thermal conductivity measurement devices600,650according to the fifth embodiment of the present invention each include either of the members.

FIGS. 18 and 19are configuration diagrams of other thermal conductivity measurement devices according to the fifth embodiment of the present invention, generally denoted by700,750, which are modifications acquired by combining the thermal conductivity measurement device110and the thermal conductivity measurement device200. InFIGS. 18 and 19, the same reference numerals asFIGS. 2 and 9denote the same or corresponding portions.

The thermal conductivity measurement device700has the heating-side axis correction member51disposed between the heating block unit5and the heating-side holding member7and the cooling-side axis correction member34disposed between the cooling block unit6and the cooling-side holding member9. On the other hand, the thermal conductivity measurement device750has the heating-side axis correction member33disposed between the heating block unit5and the heating-side holding member7and the cooling-side axis correction member52disposed between the cooling block unit6and the cooling-side holding member9.

As with the thermal conductivity measurement devices500,550,600,650,700,750according to the fifth embodiment of the present invention, one of the heating-side axis correction member51and the cooling-side axis correction member52, one of the heating-side axis correction member33and the cooling-side axis correction member34, or a combination thereof may be used as needed, and such a modification is obviously included in the technical scope of the present invention.

EXPLANATIONS OF LETTERS OR NUMERALS