JP2018128426A - Thermal analysis method of wire harness, thermal analysis device, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal analysis method of a wire harness, a thermal analysis device, and a program capable of easily simulating temperature distribution of a wire harness.SOLUTION: In a thermal analysis method of a wire harness, an electric wire bundle part 11 in which structure of a section orthogonal to a longitudinal direction in a wire harness 100A is uniform is equally divided into a finite number of sections with 1 cm length in a longitudinal direction, a thermal characteristic parameter for composing an electric wire bundle part 11a for 1 cm length is calculated by a thermal fluid analysis, and a reference thermal equivalent circuit corresponding to the electric wire bundle part 11a for 1 cm length is modeled based on the calculated thermal characteristic parameter. The reference thermal equivalent circuit is created by an electric wire bundle part equivalent circuit connected by length of the electric wire bundle part 11, and a wire harness thermal equivalent circuit corresponding to the entire wire harness is modeled based on the thermal characteristic parameter for composing the electric wire bundle part thermal equivalent circuit. A thermal network method is executed to the wire harness thermal equivalent circuit, and at least one of temperature distribution of a wire harness and an increase in a transient temperature is visualized.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a thermal analysis method, a thermal analysis apparatus, and a program for a wire harness.

  Vehicles such as electric vehicles (EV), hybrid vehicles (HEV), and plug-in hybrid vehicles (PHEV) are equipped with a wire harness that connects a battery pack disposed in the center or rear of the vehicle and an inverter disposed in the engine room. Has been. Since this wire harness is routed through the engine room, under the floor, indoors, etc. of the vehicle, it is affected by different environmental temperatures. In addition, since the wire harness includes a high-voltage electric wire that is responsible for power transmission in the drive system, the conductor temperature changes greatly during energization.

  By the way, in recent years, since the digitization of vehicles has progressed, the amount of heat generated by electronic components and wire harnesses has increased, and design based on thermal analysis is required (for example, see Non-Patent Document 1). . In addition, the application of simulation technology in the development of automotive wire harnesses is increasing (see Non-Patent Document 2, for example).

Keiji Manshita and three others, “Thermal Analysis Technology for Automobile Parts”, [online], July 2002, Furukawa Electric Time Bulletin No. 110, [Search January 10, 2017], Internet <https: // www.furukawa.co.jp/jiho/fj110/fj110_16.pdf> Yuki Noguchi, 4 others, “Application of simulation technology in the development of automotive wire harnesses”, [online], 2015 Vol. 1. Fujikura Technical Report No. 128, [Search January 10, 2017], Internet <http://www.fujikura.co.jp/rd/gihou/backnumber/pages/_icsFiles/afieldfile/2015/07/ 03 / 128_R8.pdf>

  Conventionally, there is no technology to simulate the temperature rise of the designed wire harness, and after evaluating the temperature rise using a prototype, the heat resistance standards of the wires and exterior materials used for the wire harness are determined. There is room for improvement.

  An object of the present invention is to provide a thermal analysis method, a thermal analysis apparatus, and a program for a wire harness that can easily simulate the temperature distribution of the wire harness.

  In order to achieve the above object, a thermal analysis method for a wire harness according to the present invention is a thermal analysis method for a wire harness that uses a computer to simulate a temperature distribution of the wire harness mounted on a vehicle. Among them, a wire bundle portion having a uniform cross-sectional structure perpendicular to the longitudinal direction is equally divided into a finite number of pieces with a constant length in the longitudinal direction, and the thermal characteristic parameter constituting the wire bundle portion for a fixed length A first modeling step of modeling a reference heat equivalent circuit corresponding to the wire bundle portion of a certain length based on the calculated thermal characteristic parameter, and the reference heat A wire bundle portion heat equivalent circuit is created by connecting equivalent circuits for the length of the wire bundle portion, and the entire wire harness is handled based on the thermal characteristic parameters constituting the wire bundle portion heat equivalent circuit. A second modeling step for modeling a wire harness thermal equivalent circuit; and executing a thermal network method on the wire harness thermal equivalent circuit to visualize at least one of a temperature distribution and a transient temperature rise of the wire harness. And a thermal resistance value in each heat transfer path between a plurality of members constituting the wire bundle portion for a certain length and between each member and the external environment. It is included.

  Moreover, in the thermal analysis method for the wire harness, the first modeling step further includes, when the wire harness has a branch structure, a plurality of the wire bundle portions divided for each branch are fixed in the longitudinal direction. The reference heat equivalent circuits corresponding to the wire bundle portions of a certain length are respectively divided into a finite number of lengths, and the second modeling step further includes the reference heat equivalents. Creating a plurality of wire bundle portion thermal equivalent circuits in which a circuit is connected for the length of each wire bundle portion, and modeling the wire harness heat equivalent circuit based on the plurality of wire bundle portion thermal equivalent circuits preferable.

  In the thermal analysis method for the wire harness, the second modeling step models each wire bundle portion thermal equivalent circuit as a device having a terminal for connecting to the other wire bundle portion thermal equivalent circuit, It is preferable that the plurality of devices are connected to each other via the terminals to model the wire harness thermal equivalent circuit.

  In the thermal analysis method for a wire harness, the thermal characteristic parameter preferably includes an environmental temperature of the wire harness.

  In order to achieve the above object, a thermal analysis device for a wire harness according to the present invention is a thermal analysis device for a wire harness that simulates the temperature distribution of a wire harness mounted on a vehicle, and is divided for each branch of the wire harness. And a plurality of wire bundle portions having a uniform cross-sectional structure perpendicular to the longitudinal direction are equally divided into a finite number of pieces with a fixed length in the longitudinal direction. Calculation means for calculating thermal characteristic parameters necessary for modeling each reference heat equivalent circuit corresponding to each wire bundle portion for a certain length, and each reference heat equivalent circuit for each wire bundle. A plurality of wire bundle heat equivalent circuits connected for the length of each part, and processing means for modeling the wire harness heat equivalent circuit based on the plurality of wire bundle heat equivalent circuits, and the wire harness heat equivalent circuit Against Display means for displaying at least one of a temperature distribution of the wire harness and a transient temperature rise from a calculation result of a thermal network method to be executed, and the thermal characteristic parameter is the electric wire for a certain length The thermal resistance value in each heat-transfer path | route between the some members which comprise a bundle part and between each said member and external environment is contained, It is characterized by the above-mentioned.

  In order to achieve the above object, a wire harness thermal analysis program according to the present invention is a computer-readable program that executes a wire harness thermal analysis method for simulating the temperature distribution of a wire harness mounted on a vehicle. The wire harness is divided for each branch of the wire harness, and a plurality of wire bundle portions having a uniform cross-sectional structure orthogonal to the longitudinal direction are equally divided into a finite number of pieces with a constant length in the longitudinal direction, A calculation function for calculating thermal characteristic parameters necessary for modeling each reference heat equivalent circuit corresponding to each wire bundle portion for a certain length based on each wire bundle portion for a certain length; A plurality of wire bundle part heat equivalent circuits in which the reference heat equivalent circuits are connected for the length of each wire bundle part, and a wire harness heat equivalent circuit is created based on the plurality of wire bundle part heat equivalent circuits. A display function for displaying at least one of the temperature distribution of the wire harness and the transient temperature rise from the calculation result of the thermal network method executed on the wire harness thermal equivalent circuit, Is realized on a computer.

  According to the thermal analysis method, thermal analysis apparatus, and program for the wire harness according to the present invention, the temperature distribution of the wire harness can be easily simulated.

FIG. 1 is a plan view illustrating a schematic configuration of the wire harness according to the first embodiment. FIG. 2 is a block diagram illustrating a configuration example of the thermal analysis apparatus according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a schematic configuration of the wire bundle portion of the wire harness according to the first embodiment. FIG. 4 is a cross-sectional perspective view of a portion obtained by equally dividing the wire bundle portion of the wire harness according to the first embodiment. FIG. 5 is a schematic diagram of a reference heat equivalent circuit of the wire harness according to the first embodiment. FIG. 6 is a schematic diagram of a wire bundle portion heat equivalent circuit of the wire harness according to the first embodiment. FIG. 7 is a schematic diagram of the wire harness thermal equivalent circuit according to the first embodiment. FIG. 8 is a diagram illustrating a netlist corresponding to the wire harness thermal equivalent circuit according to the first embodiment. FIG. 9 is a flowchart illustrating a procedure of the thermal analysis method according to the first embodiment. FIG. 10 is a graph showing the temperature distribution of the wire harness according to the first embodiment. FIG. 11 is a plan view illustrating a schematic configuration of the wire harness according to the second embodiment. FIG. 12 is a plan view showing the environmental temperature of the wire harness according to the second embodiment. FIG. 13 is a cross-sectional view illustrating a schematic configuration of the wire bundle portion of the wire harness according to the second embodiment. FIG. 14 is a schematic diagram of a reference heat equivalent circuit of a portion obtained by equally dividing the wire bundle portion of the wire harness according to the second embodiment. FIG. 15 is a diagram illustrating a netlist corresponding to the reference heat equivalent circuit according to the second embodiment. FIG. 16 is a diagram illustrating a net list corresponding to the wire bundle portion of the wire harness according to the second embodiment. FIG. 17 is a schematic diagram of a device model corresponding to the wire bundle portion of the wire harness according to the second embodiment. FIG. 18 is a schematic diagram of a device model corresponding to the wire harness according to the second embodiment. FIG. 19 is a schematic diagram of a wire harness thermal equivalent circuit according to the second embodiment. FIG. 20 is a flowchart illustrating a procedure of the thermal analysis method according to the second embodiment. FIG. 21 is a schematic diagram illustrating a temperature distribution of the wire harness according to the second embodiment. FIG. 22 is a schematic diagram illustrating a change over time in the temperature distribution of the wire harness according to the second embodiment. FIG. 23 is a schematic diagram of a reference heat equivalent circuit according to a modification of the second embodiment. FIG. 24 is a schematic diagram of a device model corresponding to a wire bundle portion of a wire harness according to a modification of the second embodiment. FIG. 25 is a schematic diagram of a device model corresponding to a wire harness according to a modification of the second embodiment. FIG. 26 is a schematic diagram of a wire harness heat equivalent circuit according to a modification of the second embodiment.

  DESCRIPTION OF EMBODIMENTS Embodiments of a wire harness thermal analysis method, a thermal analysis apparatus, and a program according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same. The constituent elements in the following embodiments can be variously omitted, replaced, and changed without departing from the gist of the invention.

[Embodiment 1]
FIG. 1 is a plan view illustrating a schematic configuration of the wire harness according to the first embodiment. FIG. 2 is a block diagram illustrating a configuration example of the thermal analysis apparatus according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a schematic configuration of the wire bundle portion of the wire harness according to the first embodiment. FIG. 4 is a cross-sectional perspective view of a portion obtained by equally dividing the wire bundle portion of the wire harness according to the first embodiment. FIG. 5 is a schematic diagram of a reference heat equivalent circuit of the wire harness according to the first embodiment. FIG. 6 is a schematic diagram of a wire bundle portion heat equivalent circuit of the wire harness according to the first embodiment. FIG. 7 is a schematic diagram of the wire harness thermal equivalent circuit according to the first embodiment. FIG. 8 is a diagram illustrating a netlist corresponding to the wire harness thermal equivalent circuit according to the first embodiment. FIG. 9 is a flowchart illustrating a procedure of the thermal analysis method according to the first embodiment. FIG. 10 is a graph showing the temperature distribution of the wire harness according to the first embodiment. 3 is a cross-sectional view taken along the line AA in FIG.

  As described above, the wire harness 100A shown in FIG. 1 is a battery pack disposed at the center or rear of a vehicle (not shown) such as an electric vehicle (EV), a hybrid vehicle (HEV), or a plug-in hybrid vehicle (PHEV). Connect the inverter located in the engine room. The wire harness 100A is routed through the vehicle engine room, under the floor, indoors, and the like. The wire harness 100A includes a high-voltage electric wire and a motor electric wire that are responsible for power transmission of the drive system, a low-voltage electric wire that is responsible for power transmission of the 12V power source system, and the like. In the wire harness 100A, a plurality of electric wires are collected by an exterior material such as a corrugated tube or a resin tape, and attached to a connecting component such as a multi-core connector capable of connecting a plurality of electric wires to both ends at once. In addition, the wire harness 100A may include a fixture, a protector, a grommet, and the like. The wire harness 100 </ b> A in the present embodiment includes one wire bundle portion 11 and a plurality of connector portions 13.

  The wire bundle portion 11 is a portion in the wire harness 100A where a plurality of wires are collected by an exterior material. The wire bundle portion 11 in the present embodiment has a length in the longitudinal direction of 200 cm and a uniform cross-sectional structure perpendicular to the longitudinal direction. As shown in FIGS. 3 and 4, the wire bundle portion 11 includes an exterior material 111, an electric wire 112, and a gap portion 114. The sheathing material 111 is sheathed on the electric wire 112 and protects the electric wire 112 from focusing, path regulation, and interference with other components. The exterior material 111 is made of, for example, a resin corrugated tube, a resin tape, a binding band, or the like. The electric wire 112 is a two-core shielded electric wire. The electric wire 112 includes a sheath 113, a braid 115, a covering 117, and two conductors 119 and 121. The sheath 113 is a protective outer covering that is provided outside the electric wire 112 and protects the electric wire 112. The sheath 113 is made of, for example, resin, natural rubber, chloroprene (neoprene), vinyl, or the like. The braid 115 is a so-called electromagnetic shield member for suppressing electromagnetic noise generated when a high-voltage current flows through the electric wire 112 from affecting electronic devices and the like disposed around the electric wire bundle portion 11. The coating 117 is a film-like insulating member that covers the conductors 119 and 121. The two conductors 119 and 121 are linear conductors used for power supply or signal communication. The gap 114 is a space formed between the exterior material 111 and the electric wire 112.

  The connector part 13 is a connection part for connecting to an unillustrated sub-harness, an electronic component mounted on a vehicle, or the like at both ends of each electric wire 112. The connector part 13 is, for example, a connector, and houses a connection terminal to which an electric wire 112 is connected in a resin housing.

  Next, a thermal analysis device that simulates the temperature distribution of the wire harness 100A will be described with reference to FIG. The thermal analysis device 1 can be configured using highly versatile hardware such as a personal computer. As shown in FIG. 2, the thermal analysis device 1 includes a personal computer (PC) 3 and an input / output device 5.

  The personal computer 3 is a versatile information processing apparatus, and includes a processing unit (CPU) 301 and a storage unit (memory) 302. The processing unit 301 is, for example, a central processing unit (CPU) that reads a program stored in the storage unit 302 and executes various processes and controls. The storage unit 302 is, for example, a memory such as a ROM (Read Only Memory), a RAM (Random Access Memory), and an HDD (Hard Disc Drive).

  The input / output device 5 is connected to the personal computer 3 and has a function of inputting information from the outside and sending it to the personal computer 3 and a function of displaying and outputting information sent from the personal computer 3. The input / output device 5 includes an input device 501 and an output device 502. The input device 501 includes, for example, a keyboard, a numeric keypad, a pointing device, a touch panel, and the like. The input device 501 in the present embodiment is configured with a keyboard, and includes a plurality of keys for inputting characters, numerical values, various instructions, and the like. The input device 501 receives input information from these and inputs the information to the processing unit 301 in the personal computer 3. Send. The output device 502 is composed of, for example, a CRT display, a liquid crystal display, a printer, or the like. The output device 502 in the present embodiment is configured by a liquid crystal display, and displays information on the screen based on a signal received from the processing unit 301 in the personal computer 3.

  Next, the procedure of the thermal analysis method of the wire harness 100A by the thermal analysis apparatus 1 according to the first embodiment will be described with reference to FIG. Note that this procedure is performed using spreadsheet software, circuit simulators, thermal fluid analysis software, and the like that operate on the thermal analysis apparatus 1. Here, the spreadsheet software operates on the processing unit 301 of the personal computer 3 and performs summation and analysis of numerical data or calculation of a thermal circuit method. The circuit simulator operates on the processing unit 301 of the personal computer 3, models the thermal equivalent circuit of the wire harness as an electronic circuit, and simulates its operation and characteristics. The thermal fluid analysis software operates on the processing unit 301 of the personal computer 3 and performs numerical calculations regarding wind flow, heat transfer, and the like to obtain thermal characteristics such as thermal resistance.

  First, in step S101, the wire bundle portion 11 having a uniform cross-sectional structure orthogonal to the longitudinal direction in the wire harness 100A is equally divided into a finite number of pieces with a fixed length (here, 1 cm), and the length is 1 cm. The reference heat equivalent circuit 21a corresponding to the minute wire bundle portion 11a is created. In the present embodiment, the wire bundle portion 11 is equally divided by a length of 1 cm, and the reference heat equivalent circuit 21a corresponding to the wire bundle portion 11a having a length of 1 cm is created.

Here, heat transfer in the wire harness 100A will be described. The heat transfer in the wire harness 100 </ b> A is performed between a plurality of members constituting the wire bundle portion 11 or on each member. Here, the plurality of members constituting the wire bundle portion 11 include an exterior material 111, a sheath 113, a gap portion 114, a braid 115, a covering 117, and conductors 119 and 121. The heat transfer in the longitudinal direction of the wire harness 100A is performed on each member. The thermal resistance Rx [° C./W] in the heat transfer in the longitudinal direction of the wire harness 100A is calculated from the following equation (1). Note that heat conduction and fluid movement in the gap 114 are not considered because they have very little influence.
Rx = L / λS (1)
L: Length in the direction of heat transfer [m]
λ: thermal conductivity [° C./(K·m)]
S: sectional area [m ^ 2]

On the other hand, the heat transfer in the radial direction of the wire harness 100A is performed between a plurality of members and between each member and the external environment 123, for example, conductor 119 → cover 117 → braid 115 → sheath 113 → exterior material 111 → external environment 123. Between. Here, the external environment 123 means an environment where the wire harness 100A is scheduled to be routed in the vehicle. Therefore, the temperature of the external environment 123 is the environmental temperature. The thermal resistance Ry [° C./W] in the radial heat transfer of the wire harness 100A is obtained by calculating the temperature rise of each member by thermal fluid analysis. That is, in the thermal fluid analysis, the wire bundle portion 11a having a length of 1 cm shown in FIG. 4 is modeled. Assuming an infinitely extended wire harness by setting symmetrical boundaries on both cross-sections of the wire bundle portion 11a of 1 cm in length (setting in which the heat flow and fluid do not enter and exit in the longitudinal direction of the wire harness 100A) Calculate the temperature rise. From this calculation result, the temperature difference and heat flow between each member are extracted, and the thermal resistance Ry is obtained from the following equation (2).
Ry = ΔT _XY / HF _XY (2)
ΔT _XY : temperature difference between member X and member Y [° C.]
HF _XY : Heat flow of member X-member Y [W]

  The thermal resistance in the longitudinal direction of the wire harness 100A in this embodiment is calculated using the exterior material 111, the braid 115, and the conductors 119 and 121. That is, the coating 117 and the sheath 113 are resin materials, and have a thermal conductivity much smaller than that of the metal, and the thermal resistance is much larger than that of the conductors 119 and 121 and the braid 115. Therefore, it is considered that the covering 117 and the sheath 113 do not greatly affect the heat transfer in the longitudinal direction of the wire harness, and these are ignored. Here, the thermal resistances Rx in the longitudinal direction of the wire harnesses of the conductors 119 and 121, the braid 115, and the exterior material 111 are R1, R2, and R3. A thermal equivalent circuit in the longitudinal direction of the wire harness 100A is created using these thermal resistances R1 to R3. R1 represents the thermal resistance of two conductors.

  The thermal resistance in the radial direction of the wire harness 100A in the present embodiment is the thermal resistance R12, R23, R3amb between the conductor and the braid, between the braid and the exterior material, and between the exterior material and the external environment. The thermal resistance R12 between the conductor and the braid is obtained from a thermal fluid analysis. The conductor-to-braid thermal resistance R12 assumes that the Joule heat Q of the two conductors 119, 121 is all transferred to the braid 115 through the coating 117, and the maximum temperature of the conductor 119 (121) and the maximum temperature of the braid 115. The temperature difference is calculated by dividing the temperature difference by the sum of the Joule heats Q of the two conductors 119 and 121. It is assumed that the temperatures of the two conductors 119 and 121 are equivalent and there is no heat transfer between them.

  Similarly, the thermal resistance R23 between the braid and the exterior material is obtained from the thermal fluid analysis. As shown in FIG. 3, the heat transfer form from the braid 115 to the sheath 113 is heat conduction. In addition, heat transfer from the sheath 113 to the exterior material 111 is caused by radiative heat transfer and convective heat transfer when the wire 112 is in the center of the exterior material 111 and the two are not in contact with each other. All the Joule heat Q of the two conductors 119 and 121 moves to the exterior material 111 through these heat transfer paths. Therefore, the thermal resistance R23 between the braid and the exterior material calculates the temperature difference between the maximum temperature of the braid 115 and the average temperature of the exterior material 111, and this temperature difference is the sum of the Joule heat Q of the two conductors 119 and 121. Find by dividing by.

  Similarly, the thermal resistance R3amb between the exterior material and the external environment is obtained from the thermal fluid analysis. As shown in FIG. 3, the heat transfer form from the exterior material 111 to the external environment 123 is radiant heat transfer and convection heat transfer, and the Joule heat Q of the two conductors 119 and 121 passes through these heat transfer paths. All move to the external environment 123. Therefore, the thermal resistance R3amb between the exterior material and the external environment calculates the temperature difference between the average temperature of the exterior material 111 and the environmental temperature, and divides this temperature difference by the total Joule heat Q of the two conductors 119 and 121. By seeking.

The reference heat equivalent circuit 21a of the wire bundle portion 11a having a length of 1 cm can be expressed using thermal resistances R12, R23, and R3amb as shown in FIG. The temperature rise in the reference heat equivalent circuit 21a can be obtained from the Joule heat Q of the conductors 119, 121 and the thermal resistances R12, R23, R3amb. Since the Joule heat Q generated in the conductors 119 and 121 is equal to the amount of heat flowing out from the conductors 119 and 121 to the braid 115, the following equation (3) is established.
Q = (T1-T2) / R12 (3)
T1: Conductor temperature T2: Braiding temperature

Further, since the amount of heat flowing into the braid 115 from the conductors 119 and 121 is equal to the amount of heat flowing out of the braid 115 into the exterior material 111, the following expression (4) is established.
(T1-T2) / R12 = (T2-T3) / R23 (4)
T3: exterior material temperature

Further, since the amount of heat flowing from the conductors 119 and 121 into the braid 115 is equal to the amount of heat flowing out from the braid 115 to the exterior material 111, the following equation (5) is established.
(T2-T3) / R23 = (T3-Tamb) / R3amb (5)
Tamb: Environmental temperature

  By solving the simultaneous equations comprising the above (3) to (5), the temperatures of the heat transfer paths of the conductors 119, 121, the braid 115, the exterior material 111, and the external environment 123 can be obtained.

  Returning to FIG. 9, in step S <b> 102, the reference heat equivalent circuit 21 a created in step S <b> 101 is connected by the length of the wire bundle portion 11 to create the wire bundle portion heat equivalent circuit 21 of the wire bundle portion 11. As shown in FIGS. 6 and 7, the wire bundle portion thermal equivalent circuit 21 of the wire bundle portion 11 is obtained by changing the reference heat equivalent circuit 21 a of the wire bundle portion 11 a for a length of 1 cm using thermal resistances R1 to R3. It is created by connecting the length of the bundle portion 11. Here, the wire bundle portion 11 has a longitudinal length of 200 cm. Since the wire harness 100A in the present embodiment has no branch and has a uniform cross-sectional structure perpendicular to the longitudinal direction of the wire bundle portion 11, the wire bundle portion heat equivalent circuit 21 of the wire bundle portion 11 is a wire harness. It becomes a 100 A thermal equivalent circuit. Therefore, the wire bundle heat equivalent circuit 21 corresponding to the 200 cm long wire bundle portion 11 is the same as the wire harness heat equivalent circuit 22 corresponding to the wire harness 100A.

  The wire harness heat equivalent circuit 22 corresponding to the wire harness 100A having a length of 200 cm is similar to the reference heat equivalent circuit 21a of the wire bundle portion 11a having a length of 1 cm at 600 nodes (nodes) excluding the external environment 123. Then, simultaneous equations are created according to the conservation law of each heat flow rate. Actually, the wire harness heat equivalent circuit 22 is obtained by inputting the information of the netlist 7 shown in FIG. 8 into spreadsheet software, performing matrix calculation, and solving simultaneous equations. Here, the netlist 7 is a text file used when, for example, a thermal equivalent circuit is simulated by a circuit simulator. The thermal equivalent circuit to be analyzed is composed of what thermal characteristic parameters and which node is It is a list which shows how it is connected. For example, as shown in FIG. 8, the netlist 7 in the present embodiment includes two member nodes and thermal characteristic parameters between the two members. This thermal characteristic parameter includes a thermal resistance value in each heat transfer path between a plurality of members constituting the wire bundle portion of a certain length and between each member and the external environment 123.

  A heat generation amount is separately set for each of the nodes (conductor nodes) N001 to N200 in the wire harness heat equivalent circuit 22 shown in FIG. The external environment 123 in the wire harness heat equivalent circuit 22 sets a desired environmental temperature at each of the nodes N601 to N800 shown in FIG. For example, in the wire harness 100A having a length of 200 cm, when the front 30 cm is an engine room environment and the rear 170 cm is an underfloor and indoor environment, the environmental temperature of the node N601 to the node N630 is 100 ° C., and the node N631 to the node N800 are the environmental temperature 40. ℃.

  Returning to FIG. 9, in step S103, a spreadsheet or a circuit simulator is executed for the wire bundle heat equivalent circuit 21 created in step S102, that is, the wire harness heat equivalent circuit 22, and the temperature distribution of the wire harness 100A is output. Display on the device 502. An example of the temperature distribution of the wire harness 100A displayed on the output device 502 is shown in FIG. In the graph shown in FIG. 10, the wire harness length is set on the horizontal axis, and the temperature / environment temperature of the wire harness is set on the vertical axis.

  As described above, in the thermal analysis method for the wire harness according to the present embodiment, the wire bundle portion 11 having a uniform cross-sectional structure is equally divided into a length of 1 cm in the longitudinal direction, and the wire bundle portion 11a having a length of 1 cm. Are calculated, and a reference heat equivalent circuit 21a corresponding to the wire bundle portion 11a having a length of 1 cm is modeled based on the calculated thermal resistances R12, R23, R3amb. Then, the reference heat equivalent circuit 21a is connected by the length of the wire bundle portion 11 through the thermal resistances R1, R2, and R3 to create the wire bundle portion heat equivalent circuit 21, and the wire bundle portion heat equivalent circuit 21 is The wire harness heat equivalent circuit 22 corresponding to the entire wire harness is modeled based on the configured thermal resistance value. A thermal network method is performed on the wire harness heat equivalent circuit 22 to visualize the temperature distribution of the wire harness 100A.

  According to the thermal analysis method, the thermal analysis apparatus, and the program for the wire harness according to the present embodiment, the wire harness 100A is equally divided to create a reference heat equivalent circuit, and the reference heat equivalent circuit is divided by the line length of the wire harness 100A. Since the wire harness thermal equivalent circuit is created by connecting them, the thermal equivalent circuit corresponding to the wire harness 100A can be easily modeled using a spreadsheet or a circuit simulator, and the wire harness 100A using this thermal equivalent circuit can be modeled. The temperature distribution of can be easily simulated.

[Embodiment 2]
FIG. 11 is a plan view illustrating a schematic configuration of the wire harness according to the second embodiment. FIG. 12 is a plan view showing the environmental temperature of the wire harness according to the second embodiment. FIG. 13 is a cross-sectional view illustrating a schematic configuration of the wire bundle portion of the wire harness according to the second embodiment. FIG. 14 is a schematic diagram of a reference heat equivalent circuit of a portion obtained by equally dividing the wire bundle portion of the wire harness according to the second embodiment. FIG. 15 is a diagram illustrating a netlist corresponding to the reference heat equivalent circuit according to the second embodiment. FIG. 16 is a diagram illustrating a net list corresponding to the wire bundle portion of the wire harness according to the second embodiment. FIG. 17 is a schematic diagram of a device model corresponding to the wire bundle portion of the wire harness according to the second embodiment. FIG. 18 is a schematic diagram of a device model corresponding to the wire harness according to the second embodiment. FIG. 19 is a schematic diagram of a wire harness thermal equivalent circuit according to the second embodiment. FIG. 20 is a flowchart illustrating a procedure of the thermal analysis method according to the second embodiment. FIG. 21 is a schematic diagram illustrating a temperature distribution of the wire harness according to the second embodiment. FIG. 22 is a schematic diagram illustrating a change over time in the temperature distribution of the wire harness according to the second embodiment.

  The thermal analysis method for a wire harness according to the second embodiment is different from the wire harness 100A according to the first embodiment in that the wire harness 100B has a branch structure. In the second embodiment, components having the same basic configuration and basic operation as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified (the same applies hereinafter).

  As illustrated in FIG. 11, the wire harness 100 </ b> B includes a plurality of wire bundle portions 11 </ b> A to 11 </ b> I and a plurality of connector portions 13. The plurality of wire bundle portions 11A to 11I in the present embodiment are obtained by dividing the wire harness 100B for each branch. Each of the plurality of wire bundle portions 11A to 11I has a uniform cross-sectional structure orthogonal to the longitudinal direction. The wire bundle portion 11A has a cross-sectional structure 12A, a length in the longitudinal direction of 20 cm, and the number of circuits is two. The wire bundle portion 11B has a cross-sectional structure 12B, a length of 20 cm, and the number of circuits is 1. The wire bundle portion 11C has a cross-sectional structure 12C, a length of 40 cm, and a number of circuits of 3. The wire bundle portion 11D has a cross-sectional structure 12D, a length of 40 cm, and a number of circuits of 3. The wire bundle portion 11E has a cross-sectional structure 12E, a length of 120 cm, and a number of circuits of 6. The wire bundle portion 11F has a cross-sectional structure 12F, is 10 cm in length, and has 3 circuits. The wire bundle portion 11G has a cross-sectional structure 12G, has a length of 80 cm, and has three circuits. The wire bundle portion 11H has a cross-sectional structure 12H, a length of 20 cm, and a circuit number of two. The wire bundle portion 11I has a cross-sectional structure 12I, a length of 20 cm, and a circuit number of one.

  In the wire harness 100B, as shown in FIG. 12, the wire bundle portions 11A to 11D and the front 50 cm of the wire bundle portion 11E are routed in the engine room environment, and the rear 70 cm and the wire bundle portions 11F to 11I of the wire bundle portion 11E are arranged. It shall be routed under the floor and in the indoor environment. That is, the front 50 cm of the 120 cm long wire bundle portion 11E is an engine room environment, and the rear 70 cm is an underfloor and indoor environment. As shown in FIG. 13, the wire bundle portion 11 </ b> E includes an exterior material 111, three motor wires 201, two high voltage wires 203, and one low voltage wire 205.

  Next, the procedure of the thermal analysis method of the wire harness 100B by the thermal analysis apparatus 1 according to the second embodiment will be described with reference to FIG. Note that this procedure is performed using spreadsheet software, circuit simulators, thermal fluid analysis software, and the like that operate on the thermal analysis apparatus 1.

  First, in step S201, the wire harness 100B is divided into a plurality of wire bundle portions 11A to 11I for each branch, and the divided plurality of wire bundle portions 11A to 11I are each finite in a length of 1 cm in the longitudinal direction. A reference heat equivalent circuit corresponding to each wire bundle portion having a length of 1 cm is created. Here, for example, when the wire bundle portion 11E is equally divided into a finite number of 1 cm in the longitudinal direction, the reference heat equivalent circuit 41Ea corresponding to the wire bundle portion 11Ea for a length of 1 cm is described in the first embodiment. Create as you did. 13 and 14 show a reference heat equivalent circuit 41Ea corresponding to the wire bundle portion 11Ea having a length of 1 cm. As shown in FIG. 13, the wire bundle portion 11 </ b> Ea having a length of 1 cm in the present embodiment includes a three-phase AC motor wire 201 (3 circuits) and a high-voltage wire 203 (2 circuits) for supplying power from the battery pack to the inverter. ), And a low-voltage electric wire 205 (one circuit) for supplying power to an auxiliary battery (12V) mounted in the engine room.

  The thermal resistance in the heat transfer in the radial direction of the wire harness 100B is obtained from the temperature difference and the heat flow between the members constituting the wire bundle portion 11Ea having a length of 1 cm by the method described above. Here, the node N001 is disposed on the conductor of the low-voltage electric wire 205 inserted through the center of the wire bundle portion 11Ea having a length of 1 cm. The node N101 is disposed on the conductor of the motor electric wire 201. The node N201 is disposed on the conductor of the high voltage electric wire 203. In addition, although the motor electric wire 201 is comprised by three circuits, it assumes that the temperature of three conductors is equivalent and represents a node collectively. Moreover, although the high voltage electric wire 203 is comprised by 2 circuits, it assumes that the temperature of two conductors is equivalent and represents a node collectively. The node N301 is set to the exterior material 111 on the motor wire 201 side, and the node N401 is set to the exterior material 111 on the high voltage wire 203 side.

  In the wire bundle portion 11 </ b> Ea having a length of 1 cm, the heat generated in the low voltage electric wire 205 is radiated to the external environment via the motor electric wire 201, the high voltage electric wire 203, and the exterior material 111 due to the structure. Therefore, the thermal resistance between the node N101 of the motor wire 201 and the node N301 of the exterior material 111 is R13, and the thermal resistance between the node N301 of the exterior material 111 and the external environment is R3amb. On the other hand, the heat generated in the high voltage electric wire 203 is radiated to the external environment through the exterior material 111 when the temperature of the low voltage electric wire 205 is high. Therefore, the thermal resistance between the node N201 of the high voltage electric wire 203 and the node N401 of the exterior material 111 is R24, and the thermal resistance between the node N401 of the exterior material 111 and the node Bias in the external environment is R4amb. Further, since heat transfer occurs between the node N301 and the node N401 through the exterior material 111, the thermal resistance is set to R34.

  The thermal resistance in the heat transfer in the longitudinal direction of the wire harness 100B is calculated by the method described above, and is R0, R1, R2, R3, R4. R0 corresponds to the low voltage electric wire 205 in which the node N001 is arranged. R1 corresponds to the motor electric wire 201 in which the node N101 is arranged. R2 corresponds to the high voltage electric wire 203 in which the node N201 is arranged. R3 corresponds to the upper part of the exterior material 111 on which the node N301 is disposed. R4 corresponds to the lower part of the exterior material 111 in which the node N401 is disposed. Since the node must be arranged in the center of the wire bundle portion 11Ea having a length of 1 cm, R0 to R4 are halved in the reference heat equivalent circuit 41Ea as shown in FIGS. The thermal resistance is arranged at both ends of the node.

  In the reference heat equivalent circuit 41Ea of the wire bundle portion 11Ea having a length of 1 cm, the heat sources of the low voltage wire 205, the motor wire 201, and the high voltage wire 203 are modeled as current sources Source_101, 201, 301. In modeling the heat source, the temperature dependence can be considered using a predetermined arithmetic expression with reference to the temperatures (voltages on the circuit simulator) of the nodes N001, N101, and N201. Further, also in the thermal resistances R01, R02, R13, R24, R3amb, and R4amb, it is possible to consider the temperature dependence of the thermal resistance from the temperatures of the nodes at both ends of each thermal resistance.

  The ambient temperature is modeled by connecting it to R3amb and R4amb as a Bias voltage from the outside of the reference heat equivalent circuit 41Ea. The environmental temperature can be simulated by changing the voltage value of the Bias voltage. In the reference heat equivalent circuit 41Ea, the capacitors C0, C1, C2, C3, and C4 are connected to the nodes N001, N101, N201, N301, and N401 to express the heat capacity, thereby calculating the transient temperature rise. Is possible.

  Returning to FIG. 20, in step S <b> 202, the reference heat equivalent circuits created in step S <b> 201 are connected by the lengths of the wire bundle portions 11 </ b> A to 11 </ b> I to create a plurality of wire bundle portion heat equivalent circuits 41 </ b> A to 41 </ b> I. For example, when the reference heat equivalent circuit 41Ea of the wire bundle portion 11Ea having a length of 1 cm is connected by the length of the wire bundle portion 11E, the reference heat equivalent circuit 41Ea shown in FIG. 14 is formed to the length of the wire bundle portion 11E. Create by connecting 120 cm.

  When creating the wire bundle portion heat equivalent circuit 41E of the wire bundle portion 11E having a length of 120 cm, the net list 15 shown in FIG. 15 may be used. The net list 15 is a net list corresponding to the reference heat equivalent circuit 41Ea having a length of 1 cm. By inputting the information of the net list 15 into the spreadsheet software and performing loop processing while adding the numbers at the end of the nodes one by one, a net list 16 is created, and a desired wire bundle is created from the net list 16 A partial heat equivalent circuit 41E is created. In the net list 16 shown in FIG. 16, the reference heat equivalent circuits for 1 cm are arranged in the order of 1 cm (dotted line frame), 2 cm (dotted line frame), 3 cm (dotted line frame),. As described above, the netlist 15 is composed of nodes of two members and thermal characteristic parameters between the two members. The thermal characteristic parameters include a thermal resistance 15a, a heat capacity 15b, and a heat source 15c. The thermal resistance 15a is described with a thermal resistance value in consideration of the thermal resistance value or temperature dependency. The heat capacity 15b describes the heat capacity for each node. The heat capacity 15b is treated as an electric capacity on the circuit simulator. In the heat generation source 15c, a current value of a current flowing through each node is described. The heat source 15c is represented by a symbol of a current source in the reference heat equivalent circuit 41Ea shown in FIG. The heat source 15c is also treated as a current source on the circuit simulator.

  Here, when the net list 15 is used to model the reference heat equivalent circuit 41Ea shown in FIG. 14 for the length of the wire bundle portion 11E on the circuit simulator, a plurality of terminals as shown in FIG. It can be expressed as a device 17E having The device 17E has 14 terminals for connecting to other devices. That is, the device 17E receives inflow and outflow of heat (treated as a current value on the circuit simulator) through various electric wires (the motor electric wire 201, the high-voltage electric wire 203, the low-voltage electric wire 205) and the exterior material 111 constituting the electric wire bundle portion 11E. Terminals RC11, RC21, RC31, RC12, RC22, RC32, RP11, RP12, RP21, RP22 to be performed, terminals l1, l2, and l3 for setting the current of the low voltage electric wire 205, the motor electric wire 201, and the high voltage electric wire 203, and environmental temperature setting And a terminal Bias for performing. The current values set at the terminals 11 to 13 are connected to all the heat sources 15c (current sources) formed every 1 cm in the device 17E, and the conductor resistance of the wire and its temperature coefficient within the heat source 15c. From the temperature of the node where the heat source 15c is set (treated as a voltage on the circuit simulator), the amount of heat generated by the wire at that node (treated as a current value on the circuit simulator) is calculated. Similarly, the terminal Bias is connected to capacitors C0 to C4 and thermal resistors R3amb and R4amb arranged every 1 cm in the device.

  Returning to FIG. 20, in step S203, a plurality of devices 17A to 17I corresponding to the plurality of wire bundle portion thermal equivalent circuits 41A to 41I shown in FIG. 18 are created, and the created devices 17A to 17I are created on the circuit simulator. The wire harness heat equivalent circuit 42 which is a heat equivalent circuit of the wire harness 100B shown in FIG. Here, since the wire bundle part 11E arrange | positioned in the approximate center of the wire harness 100B has a change point of environmental temperature, it is modeled separately by engine room side 50cm and under floor & indoor side 70cm. That is, the wire bundle portion thermal equivalent circuit 41E of the wire bundle portion 11E is created separately for the device 17EA of 6 circuits / 50 cm and the device 17EB of 6 circuits / 70 cm, not the device 17E of 6 circuits / 120 cm.

  In the wire harness heat equivalent circuit 42, the low voltage electric wire 205 connects the terminal RC11 of one device and the terminal RC12 of the other device to each other, thereby causing a heat flow (current on the circuit simulator) to flow in the longitudinal direction through the exterior material. Can be considered). Moreover, the motor electric wire 201 can consider the heat flow which flows through a longitudinal direction through an exterior material by connecting the terminal RC21 of one device, and the terminal RC22 of the other device mutually. Moreover, the high voltage electric wire 203 can consider the heat flow which flows through a longitudinal direction through an exterior material by connecting the terminal RC31 of one device and the terminal RC32 of the other device mutually. The exterior material can consider the heat flow flowing in the longitudinal direction through the exterior material by connecting the terminal RP11 of one device and the terminal RP22 of the other device. Further, the terminals l1, l2, and l3 are connected together to the low-voltage electric wire 205, the motor electric wire 201, and the high-voltage electric wire 203, thereby facilitating the current setting. By setting the time-current profile to the current condition of the current flowing from the heat source 15c, it is possible to reproduce the current fluctuation in the vehicle mounted state and calculate the transient temperature rise at that time. The terminals Bias are connected together according to the environmental temperature. For example, when the environmental temperature of the engine room side 50 cm is 100 ° C. and the environmental temperature under the floor & indoor side 70 cm is 40 ° C., the terminals Bias of the devices 17A, 17B, 17C, 17D, and 17EA are collectively set to the environmental temperature 100 ° C. Connected to the corresponding voltage source. On the other hand, the terminals Bias of the devices 17EB, 17F, 17G, 17H, and 17I are collectively connected to a voltage source corresponding to an environmental temperature of 40 ° C. Note that terminals are not connected to both ends of the wire harness 100B on the assumption that there is no further heat transfer. However, if a problem such as the inability to execute processing due to the presence of the OPEN terminal on the circuit simulator occurs, the GND connection may be performed using a termination resistance larger than the thermal resistance.

  Next, in step S204, the calculation of the thermal network method is executed using a circuit simulator on the personal computer 3 for the wire harness heat equivalent circuit 42 (FIG. 19) of the wire harness 100B created in step S203. The temperature distribution of the wire harness 100B is displayed on the output device 502. An example of the temperature distribution of the wire harness 100B displayed on the output device 502 is shown in FIGS. FIGS. 21 and 22 are bar graphs showing the temperature distribution of the wire harness 100B with respect to the energization time. FIG. 21 shows the temperature of the wire harness 100B when the energization time T: 60 seconds elapses, and FIG. 22 shows the temperature of the wire harness 100B when the energization time T: 3600 seconds elapses. In other words, the higher the bar, the higher the temperature.

  As described above, in the thermal analysis method for the wire harness according to the present embodiment, the plurality of wire bundle portions 11A to 11I divided for each branch are equally divided by a length of 1 cm in the longitudinal direction, and the length is 1 cm. A reference heat equivalent circuit (for example, a reference heat equivalent circuit 41Ea) corresponding to each of the wire bundle portions 11A to 11I is created. A plurality of devices 17A to 17I in which the reference heat equivalent circuits are connected for the lengths of the wire bundle portions 11A to 11I are created, and the wire harness heat equivalent circuit 42 is modeled based on the plurality of devices 17A to 17I. Calculation of the thermal network method is executed on the wire harness heat equivalent circuit 42 using a circuit simulator, and the temperature distribution of the wire harness 100B is visualized.

  According to the thermal analysis method, the thermal analysis apparatus, and the program of the wire harness according to the present embodiment, the plurality of wire bundle portions 11A to 11I obtained by dividing the wire harness 100B for each branch are deviceized on a circuit simulator, By connecting the plurality of devices 17A to 17I to each other to create the wire harness heat equivalent circuit 42, it is possible to easily create the heat equivalent circuit of the wire harness considering the branch structure. Conventionally, when performing thermal analysis of a wire harness, it is necessary to define the node and thermal resistance from the end of the wire harness, so it is not easy to change partly, but by modifying the device, the wire harness It is possible to reduce the man-hours required for modeling and correcting the model. For example, when changing the length of the wire bundle corresponding to the device model 17EA of 6 circuits / 50 cm shown in FIG. 19, it is only necessary to describe the netlist 16 again with spreadsheet software and replace the device model 17EA.

  Further, according to the thermal analysis method, the thermal analysis apparatus, and the program for the wire harness according to the present embodiment, each device 17A to 17I has a terminal to which a Bias voltage can be applied from the outside. It is possible to calculate the temperature in consideration. In addition, the entire structure of the wire harness 100B can be easily inferred from the wire harness heat equivalent circuit 42, and the influence on the wire harness 100B due to the temperature rise can be easily examined.

[Modification of Embodiment 2]
FIG. 23 is a schematic diagram of a reference heat equivalent circuit according to a modification of the second embodiment. FIG. 24 is a schematic diagram of a device model corresponding to a wire bundle portion of a wire harness according to a modification of the second embodiment. FIG. 25 is a schematic diagram of a device model corresponding to a wire harness according to a modification of the second embodiment. FIG. 26 is a schematic diagram of a wire harness heat equivalent circuit according to a modification of the second embodiment.

  The thermal analysis method of the wire harness in the modification of the second embodiment is different from the second embodiment in that the reference heat equivalent circuit 51Ea is provided with the environmental temperature of the external environment as a fixed value in advance.

  The reference heat equivalent circuit 51Ea is obtained by adding a Bias voltage as an environmental temperature to the reference heat equivalent circuit 41Ea shown in FIG. The device 61E is a model in which the reference heat equivalent circuit 51Ea is connected by the length of the wire bundle portion 11E. In the device 61E, the terminal Bias and the terminal connected to the terminal Bias are omitted from the device 17E shown in FIG. That is, in each of the devices 61A to 61I shown in FIG. 25, the terminal Bias and the terminal connected to the terminal Bias are omitted. In the wire harness heat equivalent circuit 52, application of the Bias voltage to the devices 61A to 61D, 61EA, 61EB, and 61F to 61I is omitted.

  According to the thermal analysis method, the thermal analysis apparatus, and the program for the wire harness according to the modification of the second embodiment, each of the plurality of devices 61A to 61I has the environmental temperature of the Bias voltage as a fixed value. Can be set.

  In the first and second embodiments and the modified examples, the personal computer 3 and the input / output device 5 are configured separately, but may be configured integrally.

  Moreover, in the said Embodiment 1, 2, and the modification, although the cross-sectional structure has the uniform cross-section, the length which equally divides the wire bundle part 11 and 11A-11I into a longitudinal direction is 1 cm, However, It is limited to this It is not a thing.

  In the second embodiment, the wire harness 100B having the branch structure is divided for each branch. However, the wire harness 100B may be divided for each cross-sectional structure or for each circuit number.

  In the second embodiment and the modification, the case where the temperature distribution of the wire harness is displayed on the output device 502 by the display method as shown in FIGS. 10, 21, and 22 has been described. However, the present invention is limited to these display methods. Is not to be done.

  The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in the computer of the system or apparatus read the program. It can also be realized by processing to be executed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

DESCRIPTION OF SYMBOLS 1 Thermal analyzer 3 Personal computer 5 Input / output device 7, 15, 16 Net list 11, 11A-11I Wire bundle part 11a, 11Ea Wire bundle part for 1 cm in length 12A-12I Cross-section structure 15a Thermal resistance 15b Heat capacity 15c Heat source 17A-17I, 61A-61I Device 21, 41A-41I Wire bundle thermal equivalent circuit 21a, 41Ea, 51Ea Reference thermal equivalent circuit 22, 42, 52 Wire harness thermal equivalent circuit 100A, 100B Wire harness 111 Exterior material 112 Electric wire 115 Braid 119, 121 Conductor 123 External environment 201 Motor wire 203 High voltage wire 205 Low voltage wire 301 Processing unit 302 Storage unit 501 Input device 502 Output device

Claims (6)

A wire harness thermal analysis method that simulates the temperature distribution of a wire harness mounted on a vehicle using a computer,
A wire bundle portion having a uniform cross-sectional structure perpendicular to the longitudinal direction of the wire harness is equally divided into a finite number of pieces with a certain length in the longitudinal direction, thereby forming the wire bundle portion for a certain length. A first modeling step of calculating a thermal characteristic parameter by thermal fluid analysis and modeling a reference thermal equivalent circuit corresponding to the wire bundle portion of a certain length based on the calculated thermal characteristic parameter;
A wire bundle heat equivalent circuit in which the reference heat equivalent circuit is connected by the length of the wire bundle portion is created, and the entire wire harness is supported based on the thermal characteristic parameters constituting the wire bundle heat equivalent circuit. A second modeling step for modeling the wire harness thermal equivalent circuit;
Performing a thermal network method on the wire harness thermal equivalent circuit, and visualizing at least one of the temperature distribution and transient temperature rise of the wire harness, and
The thermal characteristic parameter includes a thermal resistance value in each heat transfer path between a plurality of members constituting the wire bundle portion of a certain length and between each member and the external environment. Thermal analysis method for wire harness. The first modeling step further includes:
When the wire harness has a branching structure, the plurality of wire bundle portions divided for each branch are equally divided into a finite number of pieces with a certain length in the longitudinal direction, and each wire bundle for a certain length is divided. Each of the reference heat equivalent circuits corresponding to the part,
The second modeling step further includes
A plurality of wire bundle portion heat equivalent circuits in which the reference heat equivalent circuits are connected for the length of each wire bundle portion are created, and the wire harness heat equivalent circuits are formed based on the plurality of wire bundle portion heat equivalent circuits. The thermal analysis method for a wire harness according to claim 1 to be modeled. The second modeling step includes
Each wire bundle heat equivalent circuit is modeled as a device having a terminal for connecting to the other wire bundle heat equivalent circuit, and a plurality of the devices are connected to each other via the terminal to heat the wire harness heat. The thermal analysis method for a wire harness according to claim 2, wherein an equivalent circuit is modeled. The thermal analysis method for a wire harness according to any one of claims 1 to 3, wherein the thermal characteristic parameter includes an environmental temperature of the wire harness. A wire harness thermal analysis device that simulates a temperature distribution of a wire harness mounted on a vehicle,
A plurality of electric wire bundle portions that are divided for each branch of the wire harness and have a uniform cross-sectional structure perpendicular to the longitudinal direction are equally divided into a finite number of pieces with a constant length in the longitudinal direction. Calculation means for calculating each thermal characteristic parameter necessary for modeling each reference heat equivalent circuit corresponding to each wire bundle portion for a certain length based on each wire bundle portion for a minute;
A plurality of wire bundle heat equivalent circuits are created by connecting the reference heat equivalent circuits for the length of each wire bundle portion, and a wire harness heat equivalent circuit is modeled based on the plurality of wire bundle heat equivalent circuits. Processing means to
Displaying means for displaying at least one of the temperature distribution and transient temperature rise of the wire harness from the calculation result of the thermal network method executed for the wire harness thermal equivalent circuit,
The thermal characteristic parameter includes a thermal resistance value in each heat transfer path between a plurality of members constituting the wire bundle portion of a certain length and between each member and the external environment. Thermal analysis device for wire harness. A computer-readable program for executing a thermal analysis method of a wire harness for simulating a temperature distribution of a wire harness mounted on a vehicle,
A plurality of electric wire bundle portions that are divided for each branch of the wire harness and have a uniform cross-sectional structure perpendicular to the longitudinal direction are equally divided into a finite number of pieces with a constant length in the longitudinal direction. A calculation function for calculating thermal characteristic parameters necessary for modeling each reference heat equivalent circuit corresponding to each wire bundle portion for a certain length, based on each wire bundle portion for a minute;
A plurality of wire bundle heat equivalent circuits are created by connecting the reference heat equivalent circuits for the length of each wire bundle portion, and a wire harness heat equivalent circuit is modeled based on the plurality of wire bundle heat equivalent circuits. Processing functions to
From the calculation result of the thermal network method executed for the wire harness thermal equivalent circuit, a display function for displaying at least one of the temperature distribution and transient temperature rise of the wire harness,
A program to make a computer realize.

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