JP2004354243A - Thermal degradation diagnostic device of equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal degradation diagnostic device of equipment having high versatility and reliability. <P>SOLUTION: This device is equipped with a metal rod-shaped body 4, a metal block 7 provided with a hole 8a having a prescribed length into which the metal rod-shaped body is inserted, a low-melting point alloy 8 having a creep fracture characteristic, stuck with a prescribed sticking area onto the metal rod-shaped body and the hole by being poured into the hole in the molten state in the state where the metal rod-shaped body is inserted into the hole, an elastic body 6 for pressing the metal block so as to generate a prescribed shearing stress on the sticking face between the metal rod-shaped body and the low-melting point alloy, and a detection display means 10a for detecting and displaying movement of the metal block by an elastic force of the elastic body, generated by creep shear fracture of the low-melting point alloy caused by a heat load at a prescribed temperature for a prescribed time. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thermal degradation diagnosis device that detects and displays thermal degradation of devices such as electric devices and electronic devices.
[0002]
[Prior art]
Equipment such as electricity, electronic components, and their aggregates, electrical and electronic machines, can be thermally degraded during long-term operation due to heat generated by themselves or heat from the surroundings, and exhibit the expected performance. Disappears, resulting in a so-called life. The degree of progress of thermal degradation is remarkable as the temperature is higher and the time during which the temperature is exposed is longer.
[0003]
As a device for diagnosing thermal deterioration of such equipment, in a gate drive device of a power converter, the difference in the coefficient of linear expansion between the printed board of the gate drive device and the printed board is larger than any component mounted on the printed board. A test piece made of a material is soldered and mounted, and when the test piece reaches a predetermined solder connection life, a solder connection portion is electrically opened by a crack to output an alarm signal (for example, Patent Document 1).
[0004]
[Patent Document 1]
JP-A-11-89214 (page 2, FIG. 1, FIG. 2)
[0005]
[Problems to be solved by the invention]
The above-described conventional technology can be applied only to electric and electronic devices in which components are mounted on a printed board, and the time during which a solder connection is opened due to the progress of solder cracks has a large individual difference, Further, even if a crack is formed, the electrical contact does not always remain open and is not always reliable.
[0006]
The present invention has been made in view of the above, and an object of the present invention is to provide a highly versatile and reliable apparatus for diagnosing thermal degradation of equipment.
[0007]
[Means for Solving the Problems]
According to the thermal degradation diagnosis apparatus for an apparatus according to the present invention, a metal rod, a metal block provided with a hole of a predetermined length through which the metal rod is inserted, and the metal rod inserted into the hole are provided. A low-melting alloy having creep rupture characteristics, which is poured into the hole in a molten state in a molten state and is fixed to the metal rod and the hole with a predetermined fixing area, and a bonding surface between the metal rod and the low-melting alloy. An elastic body that presses the metal block so as to generate a predetermined shear stress, and the low melting point alloy is subjected to creep shear fracture by a heat load at a predetermined temperature and a predetermined time, and the metal block is subjected to an elastic force of the elastic body. Detection display means for detecting and displaying that the. Has moved.
[0008]
According to the present invention, the creep rupture characteristics of the low melting point alloy are similar to the life characteristics due to the thermal load of electric equipment, electronic equipment, and the like, and when the creep rupture occurs, the metal block moves due to the elastic force of the elastic body. It is possible to accurately diagnose the thermal deterioration life of these devices.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of an apparatus for diagnosing thermal degradation of equipment according to the present invention will be described in detail with reference to the accompanying drawings.
[0010]
Embodiment 1 FIG.
Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view showing a device for diagnosing thermal degradation of equipment according to Embodiment 1 of the present invention, FIG. 2 is a longitudinal sectional view showing a state of displaying thermal degradation, and FIG. 3 shows creep rupture characteristics of eutectic solder. FIG. 4, FIG. 4 is a diagram showing the life characteristics of the aluminum electrolytic capacitor, FIG. 5 is a diagram showing a creep rupture master curve of the eutectic solder, and FIG. 6 is a line in which the capacitor life characteristics line and the eutectic solder creep rupture characteristics line are overwritten. FIG.
[0011]
In the figure, a thermal degradation diagnosis apparatus 1 installed near or inside an apparatus and placed in the same thermal environment as the apparatus is housed in a cylindrical case 2 and the base end of a metal rod 4 has a cylindrical shape. It is supported by the support block 3 and installed at the center of the case 2.
At the tip of the metal rod 4, a disk-shaped metal block 7 provided with a hole 8 a of a predetermined length into which the metal rod 4 is inserted is installed. Eutectic solder as a low melting point alloy having creep rupture characteristics is poured into the hole 8a in a molten state, and the metal rod 4 and the metal block 7 are fixed with the eutectic solder 8. The eutectic solder 8 is poured by the length of the hole 8a, and the metal rod 4 and the eutectic solder 8 are fixed to each other with a predetermined fixing area determined by the thickness of the metal rod 4 and the length of the hole 8a. I have.
[0012]
A coil spring 6 as an elastic body is inserted between the support block 3 and the metal block 7 connected by the metal rod 4, and disk-shaped insulating plates 5, 5 are mounted on both sides of the coil spring 6 to support the coil spring 6. The block 3, the coil spring 6, and the metal block 7 are insulated. A lead wire 9 connected to the base end of the metal rod 4 or the support block and a lead wire 9a connected to the metal block 7 are drawn out of the case 2 and connected in series to a power supply 11 and a display 10. Have been. The metal rod 4, the coil spring 6 as an elastic body, the metal block 7, the eutectic solder 8 as a low melting point alloy, the lead wires 9 and 9a, the power supply 11 and the display 10 constitute a detection display means 10a. When the thermal degradation diagnosis device 1 is housed in a case of the device, the case 2 may not be provided.
[0013]
Next, the operation of the thermal degradation diagnosis device 1 configured as described above will be described. Since the metal block 7 is constantly pressed by the coil spring 6 with a predetermined spring force, a predetermined shear stress is always generated on the fixing surface between the metal rod 4 and the eutectic solder 8. When placed in the same thermal environment as the equipment and subjected to a thermal load at a predetermined temperature, the eutectic solder 8 gradually undergoes creep deformation due to shear stress, and after a predetermined period (time), as shown in FIG. And the metal block 7 is pushed by the spring force and moves, falls off from the metal rod 4, disconnects the electrical connection between the metal rod 4 and the metal block 7, the display 10 is turned off, and the Displays and warns that the battery has reached the thermal degradation life.
[0014]
Next, the thermal degradation diagnosis apparatus 1 is attached to the highest temperature portion of an aluminum electrolytic capacitor, which is one of the devices whose thermal degradation temperature-lifetime characteristics are known, and the thermal degradation life is detected and displayed. The method will be described.
[0015]
The eutectic solder gradually expands under a constant shear stress that does not cause immediate breakage, and eventually breaks (breaks), that is, a so-called creep phenomenon occurs even near room temperature. FIG. 3 shows the creep strength of a portion soldered with eutectic solder against shear stress. The vertical axis indicates the shear stress of the soldered portion, and the horizontal axis indicates the rupture time. The shear stress-rupture time characteristics at each temperature (140 ° C., 70 ° C., 20 ° C.) are shown. As shown in the figure, the logarithmic graph shows linearity, and the lower the shear stress, the longer the time required for fracture, and the higher the temperature, the shorter the fracture at the same stress.
[0016]
FIG. 4 is a life characteristic diagram of a capacitor (a product guaranteed for 3,000 hours at 85 ° C.).
The vertical axis is the life time, and the horizontal axis is the operating temperature. As shown in the figure, the logarithmic graph shows linearity, and the higher the temperature, the shorter the lifetime.
[0017]
Assuming that the design use temperature of the condenser is 70 ° C., the life time of the condenser is 9000 hours, as indicated by the arrow in FIG. A method for detecting the life time using the thermal deterioration diagnosis device 1 will be described below.
[0018]
As indicated by solid arrows in FIG. 3, the shear stress at which the soldered portion breaks at 9000 hours at 70 ° C. becomes 0.28 N / mm ² . That is, if the relationship between the solder fixing area and the spring force of the thermal degradation diagnosis device 1 is set so that the shear stress becomes 0.28 N / mm ² and is installed near the capacitor, the capacitor operates for the design life time. At this time, the solder fixing surface undergoes creep shear failure, and the metal block 7 moves by being pushed by the spring force, falls off the metal rod 4, disconnects the electrical connection between the metal rod 4 and the metal block 7, and the display 10 is turned off. Turns off and indicates that the capacitor has reached the end of its thermal degradation life.
[0019]
Also, to warn that the capacitor has operated for half of the life time, as shown by a broken arrow in FIG. 3, the shear stress at which the solder fixing surface is broken at 70 ° C. and 4500 hours is 0.35 N / mm ² . What is necessary is just to set the relationship between the solder fixing area and the spring force in such a manner.
[0020]
Next, the case where the use temperature of the capacitor deviates from the designed value of 70 ° C. will be described below. As shown in FIG. 3, the creep rupture time of the portion soldered with the eutectic solder decreases as the temperature increases with the same shear stress. This is the same characteristic as the life characteristic of the capacitor shown in FIG. 4, and the thermal degradation diagnosis device 1 for equipment utilizing the creep rupture characteristic of eutectic solder qualitatively determines the capacitor even when the operating temperature deviates from the design value. Reflects the thermal aging life of
[0021]
A method for quantitatively examining this point will be described below. FIG. 5 is a diagram obtained by statistically processing the creep rupture characteristics of the soldered portion of the eutectic solder shown in FIG. The vertical axis is the shear stress, the horizontal axis is the logarithmic function value of the temperature (T in the figure) and the fracture time (t in the figure), and C is a constant. The curve shows a relatively linear tendency, and 9000 hours at 70 ° C. is indicated by a circle at the lower right in the figure. Since the horizontal axis is a function of the temperature and the rupture time as described above, it is possible to calculate the rupture time at an arbitrary temperature at a point indicated by a circle. That is, it is possible to calculate the breaking time at another temperature corresponding to 9000 hours at 70 ° C. in the creep rupture characteristics.
[0022]
FIG. 6 is a graph in which the calculation result is overwritten on the life characteristics of the capacitor shown in FIG. 4, and it can be seen that both characteristics are relatively well matched. From this, even if the capacitor is used at a temperature other than the design temperature of 70 ° C., the thermal degradation diagnosis device 1 can accurately detect the end of the life of the capacitor and display and warn the user.
[0023]
By conducting the above-mentioned studies, it is possible to quantitatively compare the life characteristics of the equipment for which the thermal aging life period is to be determined and the creep rupture characteristics of the low melting point alloy. It can be determined whether the thermal degradation diagnostic device 1 can detect the thermal degradation life of the device at the temperature that will actually be used.
[0024]
In the first embodiment, eutectic solder is used as the low melting point alloy, but other components such as solder or alloy may be used.
[0025]
Embodiment 2 FIG.
Second Embodiment A second embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a longitudinal sectional view showing a device for diagnosing thermal degradation of equipment according to Embodiment 2 of the present invention, and FIG. 8 is a longitudinal sectional view showing a state in which thermal degradation is displayed. In these drawings, the same or equivalent components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof is omitted.
[0026]
In the figure, a metal rod 24 is made longer than the metal rod 4 of the first embodiment, and an annular conductive stopper 12 insulated from the metal rod 24 by an insulating spacer 13 is fixed to the end thereof. I have. The insulating plates 5, 5 of the first embodiment are not mounted. A lead wire 9 connected to the conductive stopper 12 and a lead wire 9a connected to the metal block 7 are drawn out of the case 2 and connected in series to the power supply 11 and the display 10. The metal rod 24, the coil spring 6, the metal block 7, the eutectic solder 8, the conductive stopper 12, the lead wires 9 and 9 a, the power supply 11 and the display 10 constitute a detection display unit 20 a.
[0027]
Next, the operation of the thermal degradation diagnosis device 21 configured as described above will be described. Since the metal block 7 is always pressed by the coil spring 6 with a predetermined spring force, a predetermined shear stress is always generated on the fixing surface between the metal rod 24 and the eutectic solder 8.
When placed in the same thermal environment as the equipment and subjected to a thermal load at a predetermined temperature, the eutectic solder 8 gradually undergoes creep deformation due to shear stress, and as shown in FIG. When the metal block 7 is pushed by the spring force and moves on the metal rod 4 and abuts on the conductive stopper 12, the metal block 7 and the conductive stopper 12 are electrically connected, and the display 10 is turned on. To display and warn that the equipment has degraded due to heat. As means for detecting the movement of the metal block 7, a separate sensor or limit switch may be separately provided in the case 2.
[0028]
【The invention's effect】
The apparatus for diagnosing thermal deterioration of equipment according to the present invention comprises a metal block provided with a hole of a predetermined length through which a metal rod is inserted, and a molten state poured into the hole with the metal rod inserted through the hole. A low melting point alloy having creep rupture properties fixed to a metal rod and a hole with a predetermined fixing area and a metal block pressed to generate a predetermined shear stress on the bonding surface between the metal rod and the low melting point alloy Since the elastic body is provided, the thermal deterioration of the device can be accurately diagnosed regardless of the target device.
[Brief description of the drawings]
FIG. 1 is a vertical sectional view showing a device for diagnosing thermal deterioration of equipment according to Embodiment 1 of the present invention.
FIG. 2 is a longitudinal sectional view showing a state in which thermal deterioration is displayed.
FIG. 3 is a diagram showing creep rupture characteristics of eutectic solder.
FIG. 4 is a view showing life characteristics of an aluminum electrolytic capacitor.
FIG. 5 is a diagram showing a creep rupture master curve of eutectic solder.
FIG. 6 is a diagram in which a capacitor life characteristic line and a eutectic solder creep rupture characteristic line are overwritten.
FIG. 7 is a vertical sectional view showing a device for diagnosing thermal deterioration of equipment according to Embodiment 2 of the present invention.
FIG. 8 is a longitudinal sectional view showing a state in which thermal deterioration is displayed.
[Explanation of symbols]
1, 21 thermal degradation diagnostic device, 2 case, 3 support block, 4, 24 metal rod, 5 insulating plate, 6 coil spring, 7 metal block, 8 eutectic solder, 8a hole, 9, 9a lead wire, 10 display , 10a, 20a detection display means, 11 power supply, 12 conductive stopper, 13 insulating spacer.

Claims (3)

A metal rod,
A metal block provided with a hole of a predetermined length through which the metal rod is inserted,
In the state where the metal rod is inserted through the hole, a low-melting alloy having creep rupture properties, which is poured in a molten state into the hole and is fixed to the metal rod and the hole with a predetermined fixing area,
An elastic body that presses the metal block so as to generate a predetermined shear stress on the fixed surface of the metal rod and the low melting point alloy,
Detection display means for detecting and displaying that the low melting point alloy has undergone creep shear fracture due to a heat load at a predetermined temperature and for a predetermined time and the metal block has moved by the elastic force of the elastic body. Deterioration diagnosis device. 2. The apparatus for diagnosing thermal degradation of equipment according to claim 1, wherein the detection display means comprises the metal rod, the elastic body, the metal block, the low melting point alloy, a lead wire, a power supply and a display. . The said detection display means comprises the said metal rod-shaped body, the said elastic body, the said metal block, the said low-melting-point alloy, a conductive stopper, the said lead wire, the said power supply, and the said indicator. Thermal degradation diagnosis device for equipment.

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