Thermal analysis method, thermal analysis device, and thermal analysis program

Abstract

To provide a thermal analysis method, a thermal analysis device, and a thermal analysis program with which it is possible to conduct appropriate temperature prediction.SOLUTION: A thermal analysis method includes: setting an electric wire model 211 for calculating an electric wire calorific value by a thermal circuit network method regarding a plurality of electric wires 13 (S10); setting a heat-generating element block 31 that simulates the plurality of electric wires 13 (S12); setting a heat diffusion block 32 at a position between a plurality of electrical components 12 and the heat-generating element block 31 (S14); calculating an electric wire calorific value of the plurality of electric wires 13 by the electric wire model 211, and adding a heat amount conveyed from the electrical components 12 to the plurality of electric wires 13 to the electric wire calorific value and calculating the heat dissipation of the heat-generating element block 31 (S16); setting a boundary temperature of the plurality of electric wires 13 (S18); and predicting a temperature of the electrical components 12 by computation on the basis of the boundary temperature of the plurality of electric wires 13, the heat dissipation of the heat-generating element block 31, and heat diffusion by the heat diffusion block 32 (S20).SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a thermal analysis method, a thermal analysis device, and a thermal analysis program. [Background technology]

[0002] Conventionally, as a thermal analysis method, a thermal analysis device, and a thermal analysis program, for example, as described in Patent Document 1, a thermal analysis method, a thermal analysis device, and a thermal analysis program are known in which a wire harness is divided in the longitudinal direction, thermal characteristic parameters of the divided portions are calculated by thermal analysis, a wire harness thermal equivalent circuit corresponding to the entire wire harness obtained by connecting the divided portions based on the calculated thermal characteristic parameters, a thermal network method is executed on the wire harness thermal equivalent circuit, and the temperature distribution and temperature rise of the wire harness are visualized, thereby performing a thermal analysis of the wire harness. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-128426 Summary of the Invention [Problem to be solved by the invention]

[0004] The thermal analysis method, thermal analysis device, and thermal analysis program described above are difficult to apply to electrical junction boxes, and there is room for improvement in that it is difficult to predict the temperature rise of the electrical junction box. For example, an electrical junction box houses electrical components such as relays and electric wires connected to the terminals of the electrical components. An electrical junction box houses a large number of electrical components, and a large number of electric wires are connected and routed in a complex, intricate manner. Therefore, if the routing position and routing shape of each electric wire are set and modeled, the number of meshes becomes enormous, making modeling difficult. Alternatively, it is possible to perform a thermal analysis by simply modeling the electric wires as straight, but it is difficult to predict the appropriate temperature rise.

[0005] Therefore, an object of the present invention is to provide a thermal analysis method, a thermal analysis device, and a thermal analysis program that are capable of appropriately predicting a temperature rise. [Means for solving the problem]

[0006] That is, the thermal analysis method according to the present invention is configured to include: an electric wire model setting step of setting an electric wire model for calculating electric wire heat generation amounts by a thermal network method for a plurality of electric wires housed in an electric junction box and connected to a plurality of electric components; a heat generator block setting step of setting a heat generator block simulating the plurality of electric wires at a position spaced apart from the plurality of electric components; a heat diffusion block setting step of setting a heat diffusion block at a position between the plurality of electric components and the heat generator block; a calculation step of calculating electric wire heat generation amounts for the plurality of electric wires using the electric wire model and calculating the heat dissipation amount of the heat generator block by adding the heat conducted from the electric components to a portion of the electric wire heat generation amounts; a temperature setting step of setting boundary temperatures for the plurality of electric wires; and a thermal analysis step of calculating and predicting the temperatures of the electric components based on the boundary temperatures of the plurality of electric wires, the heat radiation amount of the heat generator block, and the heat dispersion by the heat diffusion block. [Effects of the Invention]

[0007] According to the thermal analysis method, thermal analysis device, and thermal analysis program of the present invention, it is possible to appropriately predict the temperature rise of an electrical junction box. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of an electrical connection box that is the subject of thermal analysis of a thermal analysis method, a thermal analysis device, and a thermal analysis program according to an embodiment. [Figure 2] FIG. 2 is an explanatory diagram of a heat generating block and a thermal diffusion block in the thermal analysis method, the thermal analysis device, and the thermal analysis program according to the embodiment. [Figure 3] FIG. 3 is a block diagram showing an outline of the electrical configuration of the thermal analysis device according to the embodiment. [Figure 4]FIG. 4 is an explanatory diagram of an electric wire model in the thermal analysis method, thermal analysis device, and thermal analysis program according to the embodiment. [Figure 5] FIG. 5 is an explanatory diagram of a thermal diffusion block in the thermal analysis method, the thermal analysis device, and the thermal analysis program according to the embodiment. [Figure 6] FIG. 6 is a flowchart showing a thermal analysis method according to the embodiment. [Figure 7] FIG. 7 is a flowchart showing a modified example of the thermal analysis method, the thermal analysis device, and the thermal analysis program according to the embodiment. [Figure 8] FIG. 8 is an explanatory diagram showing an example of heat flow in an electric junction box that is the target of thermal analysis by the thermal analysis device according to the embodiment. [Figure 9] FIG. 9 is an explanatory diagram showing an example of heat flow in an electric junction box that is the target of thermal analysis by the thermal analysis device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to these embodiments. Furthermore, the components in the following embodiments include those that are easily replaceable by those skilled in the art, or those that are substantially the same.

[0010] [Embodiment] The present embodiment relates to a thermal analysis method, a thermal analysis device, and a thermal analysis program. In the following description, of a first direction, a second direction, and a third direction that intersect with one another, the first direction is referred to as the "depth direction X," the second direction is referred to as the "width direction Y," and the third direction is referred to as the "height direction Z." Here, the depth direction X, the width direction Y, and the height direction Z are mutually perpendicular. The depth direction X corresponds to the depth direction of the electrical junction box. The width direction Y corresponds to the width direction of the electrical junction box. The width direction Y and the height direction Z intersect with the depth direction X. Furthermore, unless otherwise specified, each direction used in the following description represents a direction when each part is assembled to each other. Note that orthogonal here includes nearly orthogonal.

[0011] As shown in Fig. 1, an electrical junction box 10 to be subjected to thermal analysis is configured by accommodating electrical components 12 and electric wires 13 inside a case 11. The electrical junction box 10 is, for example, a box body mounted on a vehicle and accommodating electrical components 12 such as relays and fuses, with the electric wires 13 connected to the electrical components 12. The electrical junction box 10 accommodates a plurality of electrical components 12, with the electric wires 13 connected to the lower part of each electrical component 12. In other words, the electric wires 13 extend below the electrical components 12 and are routed below the electrical components 12. The electric wires 13 are, for example, coated electric wires in which the outer periphery of a conductor is covered with an insulating coating.

[0012] The thermal analysis method, thermal analysis device, and thermal analysis program according to the present embodiment are applied to, for example, thermal analysis of the terminal portion 121 of the electrical component 12 housed in the electrical junction box 10. That is, the thermal analysis method, thermal analysis device, and thermal analysis program according to the present embodiment predict the temperature or temperature rise of the terminal portion 121 of the electrical component 12 during operation of the electrical junction box 10. The terminal portion 121 is a terminal portion or crimped portion of the electrical component 12 to which the electric wire 13 is connected.

[0013] As shown in FIG. 2 , the thermal analysis method, thermal analysis device 1, and thermal analysis program according to this embodiment model the electrical junction box 10 as a three-dimensional structure to perform temperature prediction. In the thermal analysis method, thermal analysis device 1, and thermal analysis program according to this embodiment, instead of modeling each individual electric wire 13 in detail, the entire plurality of electric wires 13 is defined as a heating element block 31 and a thermal diffusion block 32 to perform thermal analysis. The heating element block 31 is a block that simulates the plurality of electric wires 13 as a heating element and is positioned below and spaced apart from the electric component 12. The thermal diffusion block 32 is positioned between the electric component 12 and the heating element block 31. The thermal diffusion block 32 is configured as a block for diffusing heat emitted from the heating element block 31. By defining the heating element block 31 and the thermal diffusion block 32, the thermal analysis method, thermal analysis device 1, and thermal analysis program according to this embodiment can reproduce the phenomenon in which the electric component 12 is heated through air by heat convection emitted from the plurality of electric wires 13, thereby enabling appropriate thermal analysis and temperature prediction.

[0014] 3, the thermal analysis device 1 includes a control unit 2, an input unit 3, and an output unit 4, and is configured by, for example, a computer system including an input / output interface, a processor, and a memory. The input unit 3 is a unit that inputs data and the like to the control unit 2, and corresponds to, for example, a keyboard, a mouse, etc. The output unit 4 is a unit that outputs the analysis results of the control unit 2, and corresponds to, for example, a monitor, a speaker, etc.

[0015] The control unit 2 is a control unit that performs thermal analysis and temperature prediction, and is configured, for example, by a computer main body. The control unit 2 includes a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc. For example, the control unit 2 loads a thermal analysis program stored in the ROM into the RAM and executes it with the CPU to perform thermal analysis and temperature prediction.

[0016] The control unit 2 includes an electric wire model setting unit 21, a heating element block setting unit 22, a thermal diffusion block setting unit 23, a temperature setting unit 24, a calculation unit 25, a thermal analysis unit 26, and a storage unit 27. The electric wire model setting unit 21, the heating element block setting unit 22, the thermal diffusion block setting unit 23, the temperature setting unit 24, the calculation unit 25, and the thermal analysis unit 26 are configured, for example, by installing a thermal analysis program into the control unit 2. Furthermore, the electric wire model setting unit 21, the heating element block setting unit 22, the thermal diffusion block setting unit 23, the temperature setting unit 24, the calculation unit 25, and the thermal analysis unit 26 may be configured as individual control units.

[0017] As shown in FIG. 4 , the electric wire model setting unit 21 sets an electric wire model 211 that calculates the electric wire heat generation amount for a plurality of electric wires 13 using a thermal network method. The electric wire model 211 is a thermal equivalent circuit of the electric wire 13. For example, a node 131A, a node 132A, and a node 133A are set at predetermined distances along the extension direction of the electric wire 13 for the conductor portion 131, the covering portion 132, and the boundary portion 133. In the electric wire model 211, thermal resistances are set between the node 131A and the node 13A, between the node 132A and the node 132A, and between the node 132A and the node 133A, respectively. The thermal resistance is set, for example, as a value obtained by dividing the length between the nodes by the product of the cross-sectional area and the thermal conductivity. The boundary portion 133 is a boundary portion between the electric wire 13 and the external space, for example, a surface portion of the electric wire 13. The electric wire model setting unit 21 sets the heat capacity of the conductor and the coating for each of the nodes 131A and 132A excluding the node 133A at the boundary portion 133. The electric wire model setting unit 21 can calculate the heat generation amount of the electric wire 13 by inputting, for example, the current flowing through the electric wire 13 and the boundary temperature of the boundary portion 133. This electric wire model 211 is set for each electric wire 13. The electric wire heat generation amount of each electric wire 13 is calculated by this electric wire model 211. Each data of the set electric wire model 211 is stored in the storage unit 27.

[0018] The heating element block setting unit 22 sets the heating element block 31. As described above, the heating element block 31 is a three-dimensional object that simulates the plurality of electric wires 13 as heating elements. The size of the heating element block 31 is set according to the size of the plurality of electric wires 13. The heating element block 31 radiates heat and transfers the heat to the electric component 12 by upward heat convection. The amount of heat radiation from the heating element block 31 is calculated by the calculation unit 25, which will be described later.

[0019] The thermal diffusion block setting unit 23 sets the thermal diffusion block 32. As described above, the thermal diffusion block 32 is a three-dimensional object that diffuses the heat H emitted upward from the heat-generating block 31. The thermal diffusion block 32 is configured by alternately stacking a plurality of plate bodies 321 arranged side by side along the depth direction X and a plurality of plate bodies 322 arranged side by side along the width direction Y in the height direction Z. The plate bodies 321 arranged side by side in the depth direction X are spaced apart, and the plate bodies 322 arranged side by side in the width direction Y are spaced apart. Furthermore, the plate bodies 321 and the plate bodies 322 stacked in the height direction Z are spaced apart. The thermal diffusion block 32 has a structure in which, for example, the plate bodies 321 and the plate bodies 322 are stacked in four layers. Note that the number of stacked plate bodies 321 and the plate bodies 322 in the thermal diffusion block 32 may be set to three or less layers or five or more layers depending on the number of electric wires 13, etc. 5, the thermal diffusion block 32 is configured such that the distance between the plate members 321 and 322, the distance between adjacent plate members 321, and the distance between adjacent plate members 322 are appropriately adjusted depending on the routing state of the electric wires 13. Although the thermal diffusion block 32 is configured to have a rectangular parallelepiped shape in FIG. 5, the shape of the thermal diffusion block 32 may be configured to have a shape other than a rectangular parallelepiped depending on the routing state of the electric wires 13.

[0020] The temperature setting unit 24 sets boundary temperatures of the multiple electric wires 13. The boundary temperatures are, for example, boundary conditions or ambient temperatures of the electric wires 13, and are set as initial values ​​of temperatures before thermal analysis is performed. For example, the boundary temperatures are set as the temperatures of the node 133A of the electric wire model 211 in FIG. 4, and are set for each node 133A of each electric wire model 211. Specifically, the boundary temperatures are set by calculating a temperature rise based on the size and heat generation amount of the electric junction box 10.

[0021] For example, in the electric wire 13, different boundary temperatures are set between a near region R1 and a far region R2 of the terminal portion 121. The near region R1 is a region of the electric wire 13 that is near the terminal portion 121, and the far region R2 is a region of the electric wire 13 that is farther than the near region R1. For example, if the length of the electric wire 13 is set to 50 cm, the region within 4 cm of the terminal portion 121 is set as the near region R1, and the region further away than 4 cm is set as the far region R2. A first boundary temperature is set in the near region R1, and a second boundary temperature different from the first boundary temperature is set in the far region R2. The first boundary temperature in the near region R1 is set to, for example, the ambient temperature of the terminal portion 121. The second boundary temperature in the far region R2 is set to a temperature lower than the first boundary temperature in the near region R1, for example, the average ambient temperature at the bottom of the case 11. In this way, more accurate temperature prediction is possible by the temperature setting unit 24 setting the boundary temperature of the electric wire 13 differently depending on the distance from the electric component 12. Note that although the boundary temperature is set in two stages here, it may be set in three or more stages.

[0022] The calculation unit 25 calculates the wire heat generation amount of the electric wires 13 and calculates the heat dissipation amount of the heating element block 31. The calculation unit 25 calculates the wire heat generation amount of each electric wire 13 using the electric wire model 211. The calculation unit 25 also calculates the heat dissipation amount of the heating element block 31 by adding the heat conducted from the electric components 12 to the plurality of electric wires 13 to a portion of the wire heat generation amount. As a specific example, FIG. 8 shows the heat flow in the electric junction box 10. In the electric junction box 10, the heat generation amount of the electric components 12 is 22.7 W, of which 11.0 W (48.5%) is dissipated to the electric wires 13. The wire heat generation amount is 18.6 W, of which 15.0 W (80.6%) escapes to the outside of the electric junction box 10. The heat generation amount of the heating element block 31 is set to 14.6 W, which is the sum of 11.0 W dissipated from the electric components 12 to the electric wires 13 and 3.6 W, which is a portion of the wire heat generation amount. 9, in the electrical junction box 10, the heat generated by the electrical components 12 is 9.8 W, of which 4.6 W (46.0%) is radiated to the electric wires 13. The heat generated by the electric wires is 7.6 W, and all of this heat is dissipated to the outside of the electrical junction box 10. Furthermore, of the 4.6 W radiated from the electrical components 12 to the electric wires 13, 1.2 W passes through the electric wires 13 and dissipates to the outside of the electrical junction box 10. The heat generated by the heating element block 31 is set to 3.4 W, which is calculated by subtracting the 1.2 W radiated to the outside of the electrical junction box 10 through the electric wires 13 from the 4.6 W radiated from the electrical components 12 to the electric wires 13.

[0023] The thermal analysis unit 26 calculates the temperature of the electrical component 12 based on the boundary temperatures of the multiple electric wires 13, the heat dissipation amount of the heating element block 31, and the heat dispersion by the thermal diffusion block 32. For example, the thermal analysis unit 26 performs a thermal fluid analysis of the state in which heat emitted from the heating element block 31 passes through the thermal diffusion block 32 and heats the electrical component 12, and calculates the temperature rise of the terminal portion 121 of the electrical component 12. By setting the heating element block 31 and the thermal diffusion block 32 without individually modeling the multiple electrical wires 13, the thermal analysis by the thermal analysis unit 26 is simplified and performed smoothly. Furthermore, in the thermal fluid analysis by the thermal analysis unit 26, the heat dissipation amount of the heating element block 31 is set based on the amount of heat conducted from the electrical component 12 to the electrical wires 13, so that the conduction of heat from the electrical component 12 to the electrical wires 13 is taken into account while performing the thermal fluid analysis.

[0024] The storage unit 27 stores various data related to thermal analysis in the thermal analysis device 1. For example, the storage unit 27 stores setting data for the electric wire model 211, setting data for the heating element block 31, setting data for the thermal diffusion block 32, and the like.

[0025] Next, a thermal analysis method, the operation of the thermal analysis device 1, and the execution of the thermal analysis program according to this embodiment will be described.

[0026] Fig. 6 is a flowchart showing a thermal analysis method according to this embodiment. The flowchart in Fig. 6 also shows the operation of the thermal analysis apparatus 1 and the execution of the thermal analysis program. The flowchart in Fig. 6 is executed by, for example, the control unit 2 of the thermal analysis apparatus 1.

[0027] As shown in step S10 (hereinafter simply referred to as "S10"; the same applies to S10 and subsequent steps) in FIG. 6, a setting step of the electric wire model 211 is performed. This setting step is a step of setting the electric wire model 211 according to the electric wire 13. For example, the electric wire model setting unit 21 sets the electric wire model 211 according to the specifications of the electric wire 13. Specifically, as shown in FIG. 4, values ​​such as the thermal resistance of a thermal equivalent circuit are set for each electric wire 13 connected to the electric component 12, and the electric wire model 211 is set.

[0028] Then, the process proceeds to S12 in Fig. 6, where the setting process of the heating element block 31 is performed. This setting process is a process of setting the heating element block 31. For example, as shown in Fig. 2, the heating element block setting unit 22 sets the three-dimensional heating element block 31 at a lower position within the case 11. In Fig. 2, the heating element block 31 is shown as a rectangular parallelepiped, but it may have a shape other than a rectangular parallelepiped depending on the routing state of the electric wires 13.

[0029] Then, the process proceeds to S14, where the setting step of the thermal diffusion block 32 is performed. This setting step is a step of setting the thermal diffusion block 32. For example, as shown in FIG. 2, the thermal diffusion block setting unit 23 sets the thermal diffusion block 32 between the electric component 12 and the heat generating block 31 inside the case 11. As shown in FIG. 5, the thermal diffusion block 32 is set to have a shape that combines a plate body 321 and a plate body 322. Note that the steps of S10, S12, and S14 may be performed in an order other than that described above.

[0030] 6, where a heat quantity calculation step is performed. This calculation step is a step of calculating the wire heat generation amount of the electric wires 13 and the heat radiation amount of the heating element block 31. For example, the calculation unit 25 calculates the wire heat generation amount of each electric wire 13 using the electric wire model 211. The calculation unit 25 also calculates the heat radiation amount of the heating element block 31 by adding the heat quantity conducted from the electric component 12 to the plurality of electric wires 13 to a portion of the wire heat generation amount.

[0031] Then, the process proceeds to S18, where a temperature setting step is performed. This temperature setting step is a step of setting the boundary temperatures of the electric wire model 211. For example, the temperature setting unit 24 sets the boundary temperatures of the near region R1 and the far region R2 in the electric wire model 211.

[0032] Then, the process proceeds to S20, where a thermal analysis step is performed. This thermal analysis step is a step of performing a thermal analysis of the electric junction box 10 under the set conditions of S10 to S18. For example, the thermal analysis unit 26 performs a thermal analysis of the electric junction box 10, and calculates and outputs the temperature rise of the terminal portion 121 of the electric component 12. In this case, the thermal analysis unit 26 calculates the boundary temperature of the nearby region R1 and the boundary temperature of the distant region R2 in the electric wire model 211. The boundary temperature of the nearby region R1 is output by extracting the temperature of the air surrounding the terminal portion 121 of the electric component 12.

[0033] The process then proceeds to S22, where it is determined whether the boundary temperature of the near region R1 calculated by the thermal analysis matches the boundary temperature set in S18. If the first boundary temperature of the near region R1 calculated by the thermal analysis does not match the boundary temperature set in S18, the process returns to the temperature setting step of S18. In this case, the boundary temperature of the near region R1 calculated by the thermal analysis in S20 is reset as the first boundary temperature of the near region R1 in S18, and the boundary temperature of the far region R2 calculated by the thermal analysis in S20 is reset as the second boundary temperature of the far region R2 in S18. Then, the thermal analysis step of S20 is performed.

[0034] On the other hand, if in S22 the boundary temperature of the vicinity region R1 calculated by thermal analysis matches the first boundary temperature set in S18, it is determined that the temperature prediction of the electrical component 12 is complete, and the series of control processes in FIG. 6 ends. Note that in S22, a match in the boundary temperatures includes a case where the boundary temperatures almost match. For example, if the boundary temperature of the vicinity region R1 calculated by thermal analysis is within a predetermined temperature range of the first boundary temperature set in S18, it is determined that the boundary temperature matches the first boundary temperature set in S18. The predicted boundary temperature of the vicinity region R1 is then output to the output unit 4 as the temperature rise of the terminal portion 121 of the electrical component 12.

[0035] Such a thermal analysis method, thermal analysis program, and thermal analysis device 1 can reproduce the phenomenon in which an electrical component 12 is heated by heat emitted from multiple wires 13 by setting a heating element block 31 and a heat diffusion block 32 for multiple wires 13, and can appropriately predict the temperature of the electrical component 12 through thermal fluid analysis.

[0036] As a comparative example, a plurality of electric wires 13 were each three-dimensionally modeled, and the temperature of the electric component 12 was predicted by heat transfer analysis. There were 37 electric wires 13 connected to the electric component 12. These electric wires 13 were each modeled as a linearly extending wire. As a result, the difference between the predicted temperature and the actually measured temperature was -18.5 to +19.0 degrees, and the temperature difference was large depending on the electric wire 13.

[0037] In contrast, the thermal analysis method, thermal analysis device 1, and thermal analysis program according to the present embodiment set 37 electric wires 13 as heating element blocks 31 and thermal diffusion blocks 32, and performed thermal fluid analysis, resulting in a difference between predicted and measured temperatures of -3.5 to +9.0 degrees. As a result, the thermal analysis method, thermal analysis program, and thermal analysis device 1 according to the present embodiment were able to improve the accuracy of temperature prediction.

[0038] As described above, the thermal analysis method, thermal analysis device 1, and thermal analysis program according to this embodiment can appropriately predict the temperature rise of the electrical component 12 by setting the heating element block 31 and the thermal diffusion block 32 and calculating the temperature of the electrical component 12 using the heating element block 31 and the thermal diffusion block 32.

[0039] Furthermore, in the thermal analysis method, thermal analysis device 1, and thermal analysis program according to the present embodiment, if the temperature of the electrical component 12 predicted by the thermal analysis step does not match the boundary temperature set in the temperature setting step, the thermal analysis step is performed again using the predicted temperature of the electrical component 12 as the boundary temperature. This allows the thermal analysis method, thermal analysis device 1, and thermal analysis program according to the present embodiment to accurately predict the temperature rise of the electrical component 12.

[0040] Furthermore, the thermal analysis method, thermal analysis device 1, and thermal analysis program according to the present embodiment perform thermal analysis by setting a first boundary temperature in a near region R1 according to the distance from the electric component 12, and setting a second boundary temperature different from the first boundary temperature in a far region R2 as the boundary temperature of the electric wire 13. Therefore, the thermal analysis method, thermal analysis device 1, and thermal analysis program according to the present embodiment can accurately predict the temperature rise of the electric component 12.

[0041] The thermal analysis method, thermal analysis device, and thermal analysis program according to the present invention are not limited to the above-described embodiment, and various modifications are possible within the scope of the claims. The thermal analysis method, thermal analysis device 1, and thermal analysis program according to this embodiment may be configured by appropriately combining the components of the above-described embodiment and modified examples.

[0042] For example, in the above-described embodiment, in S22 of Fig. 6, it is determined whether the boundary temperature of the vicinity region R1 calculated by thermal analysis matches the first boundary temperature set in S18. However, in addition to determining the boundary temperature, it may also be determined whether the heat dissipation amount of the heating element block 31 calculated by thermal analysis matches the heat dissipation amount of the heating element block 31 calculated in S16. Specifically, as shown in Fig. 7, if the heat dissipation amount of the heating element block 31 calculated by thermal analysis does not match the heat dissipation amount of the heating element block 31 calculated in S16, the process returns to the heat amount calculation step of S16. In this case, in S16, the total amount of heat conducted from the electrical component 12 to the multiple electrical wires 13 calculated in the thermal analysis in S20 is added to a portion of the electrical wire heat generation amount, and the result is reset as the heat dissipation amount of the heating element block 31. Then, the temperature setting step is performed again in S18, the thermal analysis step is performed again in S20, and it is determined in S22 whether the boundary temperature of the vicinity region R1 calculated by the thermal analysis matches the first boundary temperature set in S18 and whether the heat dissipation amount of the heat generating block 31 calculated by the thermal analysis matches the heat dissipation amount of the heat generating block 31 calculated in S16. The term "matching the heat dissipation amounts" used here includes cases where the heat dissipation amounts are nearly the same. Such a thermal analysis method, thermal analysis device, and thermal analysis program can more appropriately predict the temperature rise of the electric component 12.

[0043] In addition, in the above-described embodiment, the case where the electrical connection box 10 is mounted on a vehicle has been described, but the thermal analysis method, thermal analysis device, and thermal analysis program according to the present invention may also be applied to an electrical connection box that is used without being mounted on a vehicle. [Explanation of symbols]

[0044] 1:Thermal analysis device 10: Electrical junction box 12: Electrical parts 13: Electric wire 21: Wire model setting section 22: Heating element block setting section 23: Heat diffusion block setting section 24: Temperature setting section 25: Calculation section 26: Thermal analysis department 31: Heating block 32: Heat diffusion block 121:Terminal section 211: Electrical wire model R1: Neighborhood region R2: Far area

Claims

1. a wire model setting step of setting a wire model for calculating wire heat generation amounts by a thermal network method for a plurality of wires housed in an electric junction box and connected to a plurality of electric components; a heat generating block setting step of setting a heat generating block simulating the plurality of electric wires at a position spaced apart from the plurality of electric components; a thermal diffusion block setting step of setting a thermal diffusion block at a position between the plurality of electrical components and the heat generating block; a calculation step of calculating the heat dissipation amount of the heating element block by calculating the heat generation amounts of the electric wires using the electric wire model and adding the heat amount conducted from the electric component to the electric wires to a part of the heat generation amounts of the electric wires; a temperature setting step of setting boundary temperatures for the plurality of electric wires; a thermal analysis step of calculating and predicting the temperature of the electrical component based on the boundary temperatures of the plurality of electric wires, the heat dissipation amount of the heat generating block, and the heat dispersion by the thermal diffusion block, Thermal analysis method.

2. If the temperature of the electrical component predicted by the thermal analysis step does not match the boundary temperature set in the temperature setting step, the temperature of the electrical component predicted by the thermal analysis step is set as the boundary temperature, and the thermal analysis step is performed again; When the temperature of the electrical component predicted by the thermal analysis step matches the boundary temperature set in the temperature setting step, the temperature of the electrical component predicted by the thermal analysis step is set as a predicted temperature. The thermal analysis method according to claim 1 .

3. In the temperature setting step, a first boundary temperature is set in a vicinity region of a terminal portion of the electrical component to which the electric wire is connected, and a second boundary temperature different from the first boundary temperature is set in a distant region that is farther away than the vicinity region, as the boundary temperature of the electric wire; the thermal analysis step includes calculating and predicting a temperature of the terminal portion of the electrical component based on the first boundary temperature, the second boundary temperature of the plurality of electric wires, the heat dissipation amount of the heat generating block, and the heat dispersion by the thermal diffusion block. The thermal analysis method according to claim 1 or 2.

4. an electric wire model setting unit that sets an electric wire model for calculating electric wire heat generation amounts by a thermal network method for a plurality of electric wires housed in an electric junction box and connected to a plurality of electric components; a heat generating block setting unit that sets a heat generating block simulating the plurality of electric wires at a position spaced apart from the plurality of electric components; a thermal diffusion block setting unit for setting a thermal diffusion block at a position between the plurality of electrical components and the heat generating block; a calculation unit that calculates the heat dissipation amount of the heating element block by calculating the heat generation amount of the plurality of electric wires using the electric wire model and adding the heat amount conducted from the electric component to the plurality of electric wires to a part of the heat generation amount of the electric wires; a temperature setting unit that sets boundary temperatures of the plurality of electric wires; a thermal analysis unit that calculates a temperature of the electrical component based on the boundary temperatures of the plurality of electric wires, the heat dissipation amount of the heat generating block, and heat dispersion by the thermal diffusion block. Thermal analysis equipment.

5. A thermal analysis program that causes a computer to execute temperature prediction for an electrical junction box mounted on a vehicle, a wire model setting step of setting a wire model for calculating a heat generation amount of a plurality of wires housed in the electric junction box and connected to a plurality of electric components by a thermal network method; a heat generating block setting step of setting a heat generating block simulating the plurality of electric wires at a position spaced apart from the plurality of electric components; a thermal diffusion block setting step of setting a thermal diffusion block at a position between the plurality of electrical components and the heat generating block; a calculation step of calculating the heat dissipation amount of the heating element block by calculating the heat generation amounts of the electric wires using the electric wire model and adding the heat amount conducted from the electric component to the electric wires to a part of the heat generation amounts of the electric wires; a temperature setting step of setting boundary temperatures for the plurality of electric wires; a thermal analysis step of calculating the temperature of the electrical component based on the boundary temperatures of the plurality of electric wires, the heat dissipation amount of the heat generating block, and the heat dispersion by the thermal diffusion block. Thermal analysis program.

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