JP6875143B2 - Wire harness thermal analysis methods, thermal analyzers and programs - Google Patents

Description

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

Vehicles such as electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs) are equipped with a wire harness that connects a battery pack located in the center or rear of the vehicle to an inverter located in the engine room. Has been done. Since this wire harness is laid out via the engine room, underfloor, indoors, etc. of the vehicle, it is affected by different environmental temperatures. Further, since this wire harness includes a high-voltage electric wire that is responsible for power transmission of the drive system, the change in the conductor temperature during energization is also large.

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

Keiji Mashita, 3 others, "Thermal analysis technology for automobile parts", [online], July 2002, Furukawa Electric Time Signal No. 110, [Search on 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 wire harnesses for automobiles", [online], 2015 Vol. 1. Fujikura Technical Report No. 128, [Searched on 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 standard of the electric wire and exterior material used for the wire harness is determined. , There is room for improvement.

An object of the present invention is to provide a thermal analysis method, a thermal analysis device, 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, the thermal analysis method of the wire harness according to the present invention is a thermal analysis method of the wire harness that simulates the temperature distribution of the wire harness mounted on the vehicle by using a computer. Of these, the electric wire bundle portion having a uniform cross-sectional structure orthogonal to the longitudinal direction is equally divided into a finite number in the longitudinal direction with a constant length, and the thermal characteristic parameter constituting the electric wire bundle portion for a certain length. Is calculated by thermo-fluid analysis, and the first modeling step of modeling the reference heat equivalent circuit corresponding to the wire bundle portion for a certain length based on the calculated thermal characteristic parameter, and the reference heat. A wire bundle heat equivalent circuit is created by connecting the equivalent circuits by the length of the wire bundle, and the wire harness heat corresponding to the entire wire harness is generated based on the thermal characteristic parameters constituting the wire bundle heat equivalent circuit. A second modeling step of modeling the equivalent circuit and a visualization step of executing a thermal network method on the wire harness thermal equivalent circuit to visualize at least one of the temperature distribution and transient temperature rise of the wire harness. The thermal characteristic parameter includes, and the 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 . In the first modeling step, when the wire harness has a branch structure, a plurality of the wire bundle portions divided for each branch are equally divided into a finite number in the longitudinal direction with a constant length. The reference heat equivalent circuit corresponding to each wire bundle portion of a certain length is created, and in the second modeling step, each reference heat equivalent circuit is further divided by the length of each wire bundle portion. A plurality of connected wire bundle heat equivalent circuits are created, the wire harness heat equivalent circuit is modeled based on the plurality of wire bundle heat equivalent circuits, and the second modeling step is performed on each wire bundle portion. The heat equivalent circuit is modeled as a device having terminals for connecting to the other wire bundle heat equivalent circuit, and a plurality of the devices are connected to each other via the terminals to model the wire harness heat equivalent circuit. characterized in that it.

Further, in the method for thermal analysis of the wire harness, it is preferable that the thermal characteristic parameter includes the environmental temperature of the wire harness.

In order to achieve the above object, the wire harness thermal analysis device according to the present invention is a wire harness thermal analysis device that simulates the temperature distribution of a wire harness mounted on a vehicle, and is divided for each branch of the wire harness. A plurality of wire bundles having a uniform cross-sectional structure perpendicular to the longitudinal direction are equally divided into a finite number of wire bundles having a constant length in the longitudinal direction, and each of the wire bundles has a certain length. Based on this, a calculation means for calculating the thermal characteristic parameters required for modeling each reference heat equivalent circuit corresponding to each said wire bundle portion for a certain length, and each said reference heat equivalent circuit for each said wire bundle. A processing means for creating a plurality of electric wire bundle heat equivalent circuits connected by the length of the part and modeling a wire harness heat equivalent circuit based on the plurality of wire bundle heat equivalent circuits, and the wire harness heat equivalent circuit. A display means for displaying at least one of the temperature distribution and the transient temperature rise of the wire harness is provided from the calculation result of the thermal network method executed for the above, and the thermal characteristic parameter is for a certain length. The heat resistance value in each heat transfer path between the plurality of members constituting the electric wire bundle portion and between each member and the external environment is included, and the calculation means further includes the wire harness having a branched structure. In the case, the plurality of the electric wire bundles divided for each branch are equally divided into a finite number in the longitudinal direction with a certain length, and the reference heat equivalent corresponding to each of the electric wire bundles for a certain length. Each circuit is created, and the processing means further creates a plurality of the wire bundle heat equivalent circuits in which each reference heat equivalent circuit is connected by the length of each wire bundle, and the processing means creates a plurality of the wire bundle heat equivalent circuits. The wire harness heat equivalent circuit is modeled based on the heat equivalent circuit, and the processing means is modeled as a device having terminals for connecting each wire bundle heat equivalent circuit to another wire bundle heat equivalent circuit. It is characterized in that a plurality of the devices are connected to each other via the terminals to model the wire harness thermal equivalent circuit .

In order to achieve the above object, the 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 the wire harness mounted on the vehicle. Therefore, a plurality of electric wire bundle portions that are divided for each branch of the wire harness and have a uniform cross-sectional structure orthogonal to the longitudinal direction are equally divided into a finite number in the longitudinal direction with a constant length. With a calculation function that calculates the thermal characteristic parameters required for modeling each reference heat equivalent circuit corresponding to each wire bundle for a certain length based on each wire bundle for a certain length. , Each of the reference heat equivalent circuits is connected by the length of each of the wire bundles to create a plurality of wire bundle heat equivalent circuits, and a wire harness heat equivalent circuit is modeled based on the plurality of wire bundle heat equivalent circuits. computer and processing function, from the wire harness heat equivalent circuit calculation result of thermal network method is performed on a display function for displaying at least one of the temperature distribution and transient temperature rise of the wire harness, a to of Further, when the wire harness has a branch structure, the calculation function further divides a plurality of the wire bundle portions divided for each branch into a finite number of equal lengths in the longitudinal direction. , The reference heat equivalent circuit corresponding to each of the wire bundles for a certain length was created, and the processing function further connected each of the reference heat equivalent circuits for the length of each wire bundle. A plurality of the wire bundle heat equivalent circuits are created, the wire harness heat equivalent circuit is modeled based on the plurality of wire bundle heat equivalent circuits, and the processing function includes each of the wire bundle heat equivalent circuits. Modeling as a device having terminals for connecting to the electric wire bundle thermal equivalent circuit, and modeling the wire harness thermal equivalent circuit by connecting a plurality of the devices to each other via the terminals. To realize.

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

FIG. 1 is a plan view showing a schematic configuration of a wire harness according to the first embodiment. FIG. 2 is a block diagram showing a configuration example of the thermal analysis device according to the first embodiment. FIG. 3 is a cross-sectional view showing a schematic configuration of a wire bundle portion of the wire harness according to the first embodiment. FIG. 4 is a cross-sectional perspective view of a portion of the wire harness according to the first embodiment in which the wire bundle portion is equally divided. 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 heat equivalent circuit of the wire harness according to the first embodiment. FIG. 7 is a schematic diagram of the wire harness heat equivalent circuit according to the first embodiment. FIG. 8 is a diagram showing a netlist corresponding to the wire harness heat equivalent circuit according to the first embodiment. FIG. 9 is a flowchart showing the 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 showing 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 showing a schematic configuration of a wire bundle portion of the wire harness according to the second embodiment. FIG. 14 is a schematic view of a reference heat equivalent circuit of a portion of the wire harness according to the second embodiment in which the wire bundle portion is equally divided. FIG. 15 is a diagram showing a netlist corresponding to the reference heat equivalent circuit according to the second embodiment. FIG. 16 is a diagram showing a netlist corresponding to a wire bundle portion of the wire harness according to the second embodiment. FIG. 17 is a schematic view of a device model corresponding to the electric wire bundle portion of the wire harness according to the second embodiment. FIG. 18 is a schematic view of a device model corresponding to the wire harness according to the second embodiment. FIG. 19 is a schematic view of the wire harness heat equivalent circuit according to the second embodiment. FIG. 20 is a flowchart showing the procedure of the thermal analysis method according to the second embodiment. FIG. 21 is a schematic view showing the temperature distribution of the wire harness according to the second embodiment. FIG. 22 is a schematic view showing 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 modified example of the second embodiment. FIG. 24 is a schematic view of a device model corresponding to the wire bundle portion of the wire harness according to the modified example of the second embodiment. FIG. 25 is a schematic view of a device model corresponding to the wire harness according to the modified example of the second embodiment. FIG. 26 is a schematic view of a wire harness heat equivalent circuit according to a modified example of the second embodiment.

Hereinafter, embodiments of a thermal analysis method, a thermal analysis device, and a program for a wire harness according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment. In addition, the components in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same. In addition, the components in the following embodiments can be omitted, replaced, or changed in various ways without departing from the gist of the invention.

[Embodiment 1]
FIG. 1 is a plan view showing a schematic configuration of a wire harness according to the first embodiment. FIG. 2 is a block diagram showing a configuration example of the thermal analysis device according to the first embodiment. FIG. 3 is a cross-sectional view showing a schematic configuration of a wire bundle portion of the wire harness according to the first embodiment. FIG. 4 is a cross-sectional perspective view of a portion of the wire harness according to the first embodiment in which the wire bundle portion is equally divided. 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 heat equivalent circuit of the wire harness according to the first embodiment. FIG. 7 is a schematic diagram of the wire harness heat equivalent circuit according to the first embodiment. FIG. 8 is a diagram showing a netlist corresponding to the wire harness heat equivalent circuit according to the first embodiment. FIG. 9 is a flowchart showing the 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. Note that FIG. 3 is a cross-sectional view taken along the line AA of FIG.

As described above, the wire harness 100A shown in FIG. 1 is a battery pack arranged in 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). And the inverter located in the engine room. The wire harness 100A is routed via the engine room, underfloor, indoor, etc. of the vehicle. The wire harness 100A includes a high-voltage electric wire and a motor electric wire for power transmission of the drive system, a low-voltage electric wire for power transmission of the 12V power supply system, and the like. In the wire harness 100A, a plurality of electric wires are grouped by an exterior material such as a corrugated tube or a resin tape, and are attached to connecting parts such as a multi-core connector capable of connecting the plurality of electric wires at both ends at one time. The wire harness 100A may also include a fixture, a protector, a grommet, and the like. The wire harness 100A in the present embodiment includes one wire bundle portion 11 and a plurality of connector portions 13.

The electric wire bundle portion 11 is a portion of the wire harness 100A in which a plurality of electric wires are bundled by an exterior material. The wire bundle portion 11 in the present embodiment has a length of 200 cm in the longitudinal direction and has a uniform cross-sectional structure orthogonal to the longitudinal direction. As shown in FIGS. 3 and 4, the electric wire bundle portion 11 is composed of an exterior material 111, an electric wire 112, and a gap portion 114. The exterior material 111 is mounted on the electric wire 112 to protect the electric wire 112 from focusing, route regulation, and interference with other parts. The exterior material 111 is composed of, for example, a resin corrugated tube, a resin tape, a binding band, or the like. The electric wire 112 is a 2-core shielded electric wire. The electric wire 112 is composed of a sheath 113, a braid 115, a coating 117, and two conductors 119 and 121. The sheath 113 is provided on the outside of the electric wire 112 and is a protective outer coating that 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 by a high-voltage current flowing through the electric wire 112 from affecting electronic devices and the like arranged 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 portions 13 are at both ends of each electric wire 112 and are connecting portions for connecting to a sub-harness (not shown), an electronic component mounted on a vehicle, or the like. The connector portion 13 is, for example, a connector, and accommodates 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 by 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 device, 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 a storage unit 302 or the like 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), or an HDD (Hard Disk 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 the 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 is composed of, 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 composed of a keyboard, includes a plurality of keys for inputting characters, numerical values, various instructions, etc., and receives input information from these keys to the processing unit 301 in the personal computer 3. Send. The output device 502 includes, for example, a CRT display, a liquid crystal display, a printer, and the like. The output device 502 in the present embodiment is composed of a liquid crystal display, and displays information on the screen based on the 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 device 1 according to the first embodiment will be described with reference to FIG. In this procedure, spreadsheet software, circuit simulator, thermo-fluid analysis software, etc. that operate in the thermal analysis device 1 are used. Here, the spreadsheet software operates on the processing unit 301 of the personal computer 3 and performs aggregation and analysis of numerical data or calculation of the thermal network 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 thermo-fluid analysis software operates on the processing unit 301 of the personal computer 3, performs numerical calculations on the flow of wind, heat transfer, and the like, and obtains 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 of the wire harness 100A is equally divided into a finite number with a constant length (here, 1 cm), and the length is 1 cm. A reference heat equivalent circuit 21a corresponding to the wire bundle portion 11a of the minute is created. In the present embodiment, the electric wire bundle portion 11 is equally divided into 1 cm lengths, and a reference heat equivalent circuit 21a corresponding to the electric wire bundle portion 11a having a length of 1 cm is created.

Here, the heat transfer in the wire harness 100A will be described. The heat transfer in the wire harness 100A is performed between a plurality of members constituting the wire bundle portion 11 or on each member. Here, the plurality of members constituting the electric wire bundle portion 11 include an exterior material 111, a sheath 113, a gap portion 114, a braid 115, a coating 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). It should be noted that the heat conduction and the movement of the fluid in the gap 114 are not considered because the influence is very small.
Rx = L / λS (1)
L: Length in the direction of heat transfer [m]
λ: Thermal conductivity [° C / (K ・ m)]
S: Cross-sectional area [m ^ 2]

On the other hand, the heat transfer in the radial direction of the wire harness 100A is, for example, conductor 119 → coating 117 → braid 115 → sheath 113 → exterior material 111 → external environment 123, and so on, between a plurality of members and between each member and the external environment 123. It is done in between. Here, the external environment 123 means an environment in which the wire harness 100A is scheduled to be distributed to 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 thermo-fluid analysis. That is, in the thermo-fluid analysis, the electric wire bundle portion 11a having a length of 1 cm shown in FIG. 4 is modeled. By setting symmetrical boundaries on both cross sections of the wire bundle portion 11a having a length of 1 cm (setting that heat flow and fluid do not flow in and out in the longitudinal direction of the wire harness 100A), an infinitely extended wire harness is assumed. Calculate the temperature rise. From this calculation result, the temperature difference and the heat flow between the members 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-member Y [° C]
HF _XY : Heat flow of member X-member Y [W]

The thermal resistance of the wire harness 100A in the present embodiment in the longitudinal direction is calculated using the exterior material 111, the braid 115, and the conductors 119 and 121. That is, since the coating 117 and the sheath 113 are resin materials, the thermal conductivity is very small as compared with the metal, and the cross-sectional area is small, the thermal resistance is much larger than that of the conductors 119, 121 and the braid 115. Therefore, it is considered that the coating 117 and the sheath 113 do not significantly affect the heat transfer in the longitudinal direction of the wire harness, and these are ignored. Here, the thermal resistance Rx in the longitudinal direction of each wire harness of the conductors 119, 121, the braid 115, and the exterior material 111 is R1, R2, and R3. Using these thermal resistances R1 to R3, a thermal equivalent circuit in the longitudinal direction of the wire harness 100A is created. R1 represents the thermal resistance of two conductors.

The thermal resistance of the wire harness 100A in the present embodiment in the radial direction is 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 thermo-fluid analysis. The heat resistance R12 between the conductor and the braid is the maximum temperature of the conductor 119 (121) and the maximum temperature of the braid 115, assuming that the Joule heat Q of the two conductors 119 and 121 all move to the braid 115 through the coating 117, respectively. The temperature difference is calculated, and the temperature difference is divided 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 to each other.

Similarly, the thermal resistance R23 between the braid and the exterior material is obtained from the thermo-fluid analysis. As shown in FIG. 3, the form of heat transfer from the braid 115 to the sheath 113 is heat conduction. Further, heat transfer from the sheath 113 to the exterior material 111 is caused by radiant heat transfer and convection heat transfer when the electric wire 112 is in the center of the exterior material 111 and the two are not in contact with each other. All of the Joule heat Q of the two conductors 119 and 121 is transferred to the exterior material 111 via 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. Calculated by dividing by.

Similarly, the thermal resistance R3amb between the exterior material and the external environment is obtained from the thermo-fluid analysis. As shown in FIG. 3, the heat transfer modes from the exterior material 111 to the external environment 123 are 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. And move everything 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 environment temperature, and divides this temperature difference by the sum of the Joule heat Qs of the two conductors 119 and 121. Ask by.

As shown in FIG. 5, the reference thermal equivalent circuit 21a of the electric wire bundle portion 11a having a length of 1 cm can be represented by using the thermal resistances R12, R23, and R3amb. The temperature rise in the reference heat equivalent circuit 21a can be obtained from the Joule heat Q of the conductors 119 and 121 and the thermal resistances R12, R23 and 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) holds.
Q = (T1-T2) / R12 (3)
T1: Conductor temperature T2: Braiding temperature

Further, since the amount of heat flowing from the conductors 119 and 121 to the braid 115 and the amount of heat flowing out from the braid 115 to the exterior material 111 are equal, the following equation (4) holds.
(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 and the amount of heat flowing out from the braid 115 to the exterior material 111 are equal, the following equation (5) holds.
(T2-T3) / R23 = (T3-Tamb) / R3amb (5)
Tamb: Environmental temperature

By solving the simultaneous equations (3) to (5) above, the temperatures 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 S102, the reference heat equivalent circuit 21a created in step S101 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 electric wire bundle portion heat equivalent circuit 21 of the electric wire bundle portion 11 is a reference heat equivalent circuit 21a of the electric wire bundle portion 11a having a length of 1 cm, using thermal resistances R1 to R3. It is created by connecting the lengths of the bundle portions 11. Here, the length of the electric wire bundle portion 11 in the longitudinal direction is 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 electric wire bundle portion 11, the electric wire bundle portion thermal equivalent circuit 21 of the electric wire bundle portion 11 is a wire harness. It becomes a heat equivalent circuit of 100A. Therefore, the wire bundle heat equivalent circuit 21 corresponding to the wire bundle portion 11 having a length of 200 cm 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 has 600 nodes (nodes) excluding the external environment 123, similarly to the reference heat equivalent circuit 21a of the wire bundle portion 11a having a length of 1 cm. , Create simultaneous equations according to the conservation law of each heat flow. Actually, the wire harness thermal 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 simulating a heat equivalent circuit in a circuit simulator, for example. What kind of heat characteristic parameters are used in the heat equivalent circuit to be analyzed, and what kind of node is it? It is a list showing whether or not they are connected. The netlist 7 in the present embodiment is composed of, for example, a node of two members and a thermal characteristic parameter between the two members, as shown in FIG. This thermal characteristic parameter includes a thermal resistance value in each heat transfer path between a plurality of members constituting the electric wire bundle portion for a certain length and between each member and the external environment 123.

The amount of heat generated is separately set for each of the nodes (conductor nodes) N001 to N200 in the wire harness heat equivalent circuit 22 shown in FIG. 7. The external environment 123 in the wire harness heat equivalent circuit 22 sets a desired environmental temperature for each node of the nodes N601 to N800 shown in FIG. 7. For example, in a wire harness 100A having a length of 200 cm, when the front 30 cm is the engine room environment and the rear 170 cm is the underfloor and indoor environment, the environmental temperature of the nodes N601 to N630 is 100 ° C., and the environmental temperature of the nodes N631 to N800 is 40. Let it be ° C.

Returning to FIG. 9, in step S103, a table calculation or a circuit simulator is executed on 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. Displayed on device 502. FIG. 10 shows an example of the temperature distribution of the wire harness 100A displayed on the output device 502. In the graph shown in FIG. 10, the horizontal axis is the length of the wire harness, and the vertical axis is the temperature / environmental temperature of the wire harness.

As described above, in the method for thermal analysis of the wire harness according to the present embodiment, the electric 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 electric wire bundle portion 11a having a length of 1 cm is equally divided. The thermal resistances R12, R23, and R3amb constituting the above are calculated, and the 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, and R3amb. Then, the reference heat equivalent circuit 21a is connected via the thermal resistances R1, R2, and R3 for the length of the electric wire bundle portion 11 to create the electric wire bundle portion thermal equivalent circuit 21, and the electric wire bundle portion thermal equivalent circuit 21 is formed. The wire harness thermal equivalent circuit 22 corresponding to the entire wire harness is modeled based on the constituent thermal resistance values. The thermal network method is executed on the wire harness heat equivalent circuit 22, and the temperature distribution of the wire harness 100A is visualized.

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

[Embodiment 2]
FIG. 11 is a plan view showing 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 showing a schematic configuration of a wire bundle portion of the wire harness according to the second embodiment. FIG. 14 is a schematic view of a reference heat equivalent circuit of a portion of the wire harness according to the second embodiment in which the wire bundle portion is equally divided. FIG. 15 is a diagram showing a netlist corresponding to the reference heat equivalent circuit according to the second embodiment. FIG. 16 is a diagram showing a netlist corresponding to a wire bundle portion of the wire harness according to the second embodiment. FIG. 17 is a schematic view of a device model corresponding to the electric wire bundle portion of the wire harness according to the second embodiment. FIG. 18 is a schematic view of a device model corresponding to the wire harness according to the second embodiment. FIG. 19 is a schematic view of the wire harness heat equivalent circuit according to the second embodiment. FIG. 20 is a flowchart showing the procedure of the thermal analysis method according to the second embodiment. FIG. 21 is a schematic view showing the temperature distribution of the wire harness according to the second embodiment. FIG. 22 is a schematic view showing a change over time in the temperature distribution of the wire harness according to the second embodiment.

The method for thermal analysis of the 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 branched structure. In the second embodiment, those having the same basic configuration and basic operation as the first embodiment are designated by the same reference numerals, and the description thereof will be omitted or simplified (hereinafter, the same applies).

As shown in FIG. 11, the wire harness 100B includes a plurality of wire bundle portions 11A to 11I and a plurality of connector portions 13. The plurality of electric 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 electric wire bundle portions 11A to 11I has a uniform cross-sectional structure orthogonal to the longitudinal direction. The electric wire bundle portion 11A has a cross-sectional structure of 12A, has a length of 20 cm in the longitudinal direction, and has two circuits. The electric wire bundle portion 11B has a cross-sectional structure of 12B, has a length of 20 cm, and has one circuit number. The electric wire bundle portion 11C has a cross-sectional structure of 12C, has a length of 40 cm, and has three circuits. The electric wire bundle portion 11D has a cross-sectional structure of 12D, has a length of 40 cm, and has three circuits. The electric wire bundle portion 11E has a cross-sectional structure of 12E, a length of 120 cm, and a number of circuits of 6. The electric wire bundle portion 11F has a cross-sectional structure of 12F, has a length of 10 cm, and has three circuits. The electric wire bundle portion 11G has a cross-sectional structure of 12G, has a length of 80 cm, and has three circuits. The electric wire bundle portion 11H has a cross-sectional structure of 12H, has a length of 20 cm, and has two circuits. The electric wire bundle portion 11I has a cross-sectional structure of 12I, has a length of 20 cm, and has one circuit.

As shown in FIG. 12, in the wire harness 100B, the wire bundle portions 11A to 11D and the front 50 cm of the wire bundle portion 11E are arranged in the engine room environment, and the wire bundle portions 11E 70 cm behind and the wire bundle portions 11F to 11I are arranged. It shall be routed under the floor and in the indoor environment. That is, 50 cm in front of the wire bundle portion 11E having a length of 120 cm is used as the engine room environment, and 70 cm behind is used as the underfloor and indoor environment. As shown in FIG. 13, the electric wire bundle portion 11E is composed of an exterior material 111, three motor electric wires 201, two high-voltage electric wires 203, and one low-voltage electric wire 205.

Next, the procedure of the thermal analysis method of the wire harness 100B by the thermal analysis device 1 according to the second embodiment will be described with reference to FIG. In this procedure, spreadsheet software, circuit simulator, thermo-fluid analysis software, etc. that operate in the thermal analysis device 1 are used.

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

The thermal resistance in the radial heat transfer 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 arranged on the conductor of the low-voltage electric wire 205 inserted in the center of the electric wire bundle portion 11Ea having a length of 1 cm. The node N101 is arranged on the conductor of the motor electric wire 201. The node N201 is arranged on the conductor of the high-voltage power line 203. Although the motor wire 201 is composed of three circuits, the nodes are collectively expressed on the assumption that the temperatures of the three conductors are equivalent. Further, although the high-voltage power line 203 is composed of two circuits, the nodes are collectively represented by assuming that the temperatures of the two conductors are equivalent. The node N301 is set to the exterior material 111 on the motor electric wire 201 side, and the node N401 is set to the exterior material 111 on the high voltage electric wire 203 side.

In the electric wire bundle portion 11Ea having a length of 1 cm, the heat generated by the low-voltage electric wire 205 is structurally dissipated to the external environment via the motor electric wire 201, the high-voltage electric wire 203, and the exterior material 111. 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 dissipated to the external environment via 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 power line 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 of the external environment is R4amb. Further, since heat transfer occurs between the node N301 and the node N401 via 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 wire 205 in which the node N001 is located. R1 corresponds to the motor wire 201 in which the node N101 is arranged. R2 corresponds to the high-voltage power line 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 arranged. R4 corresponds to the lower part of the exterior material 111 on which the node N401 is arranged. 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. 14 and 15. The thermal resistance is placed at both ends of the node.

In the reference heat equivalent circuit 41Ea of the electric wire bundle portion 11Ea having a length of 1 cm, the heat generating sources of the low-voltage electric wire 205, the motor electric wire 201, and the high-voltage electric wire 203 are modeled as current sources Source_101, 201, 301. In modeling the heat generation source, the temperature of each of the nodes N001, node N101, and node N201 (voltage on the circuit simulator) is referred to, and the temperature dependence can be considered by using a predetermined arithmetic expression. 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 temperature of the nodes at both ends of each thermal resistance.

The environmental temperature is modeled by connecting 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. Further, in the reference heat equivalent circuit 41Ea, the transient temperature rise is calculated by connecting capacitors C0, C1, C2, C3, and C4 to each node N001, N101, N201, N301, and N401 to express the heat capacity. Is possible.

Returning to FIG. 20, in step S202, the reference heat equivalent circuits created in step S201 are connected by the lengths of the wire bundle portions 11A to 11I to create a plurality of wire bundle portion heat equivalent circuits 41A to 41I. For example, when the reference heat equivalent circuit 41Ea of the electric wire bundle portion 11Ea having a length of 1 cm is connected by the length of the electric wire bundle portion 11E, the reference heat equivalent circuit 41Ea shown in FIG. 14 is formed by the length of the electric wire bundle portion 11E. Create by connecting 120 cm.

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

Here, when the reference heat equivalent circuit 41Ea shown in FIG. 14 is connected and modeled by the length of the electric wire bundle portion 11E on the circuit simulator using the above netlist 15, a plurality of terminals as shown in FIG. 17 are connected. Can be expressed as a device 17E having the above. The device 17E has 14 terminals for connecting to other devices. That is, the device 17E allows inflow and outflow of heat (treated as a current value on the circuit simulator) through various electric wires (motor electric wire 201, high-voltage electric wire 203, low-voltage electric wire 205) and exterior material 111 constituting the electric wire bundle portion 11E. Terminals RC11, RC21, RC31, RC12, RC22, RC32, RP11, RP12, RP21, RP22, terminals l1, l2, l3 for setting the current of low-voltage electric wire 205, motor electric wire 201, and high-voltage electric wire 203, and environmental temperature setting. It has a terminal Bias that performs the above. The current values set at the terminals l1 to l3 are connected to all the heat generating sources 15c (current sources) configured every 1 cm in the device 17E, and the conductor resistance of the electric wire and its temperature coefficient inside the heat generating source 15c. , It can be obtained by calculating the amount of heat generated by the electric wire at that node (handled as a current value on the circuit simulator) from the temperature of the node where the heat generation source 15c is set (handled as a voltage on the circuit simulator). Similarly, the terminal Bias is connected to capacitors C0 to C4 and thermal resistances 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 thermal equivalent circuits 41A to 41I shown in FIG. 18 are created, and the created plurality of devices 17A to 17I are mounted on the circuit simulator. The wire harness thermal equivalent circuit 42, which is the thermal equivalent circuit of the wire harness 100B shown in FIG. 19, is created by connecting to each other via terminals. Here, since the wire bundle portion 11E arranged substantially in the center of the wire harness 100B has a change point of the environmental temperature, it is modeled separately for the engine room side 50 cm and the underfloor & indoor side 70 cm. That is, the electric wire bundle portion thermal equivalent circuit 41E of the electric wire bundle portion 11E is not created separately for the device 17E of 6 circuits / 120 cm, but separately for the device 17EA of 6 circuits / 50 cm and the device 17EB of 6 circuits / 70 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, so that the heat flow flowing in the longitudinal direction through the exterior material (current on the circuit simulator). Can be treated as). Further, the motor electric wire 201 can consider the heat flow flowing in the longitudinal direction through the exterior material by connecting the terminal RC21 of one device and the terminal RC22 of the other device to each other. Further, the high-voltage power line 203 can consider the heat flow flowing in the longitudinal direction through the exterior material by connecting the terminal RC31 of one device and the terminal RC32 of the other device to each other. By connecting the terminal RP11 of one device and the terminal RP22 of the other device to the exterior material, it is possible to consider the heat flow flowing in the longitudinal direction through the exterior material. Further, by connecting the terminals l1, l2, and l3 together to the low-voltage electric wire 205, the motor electric wire 201, and the high-voltage electric wire 203, the current setting of each can be facilitated. By setting the time-current profile in the current condition of the current flowing from the heat generation 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 50 cm on the engine room side is 100 ° C. and the environmental temperature of 70 cm under the floor and indoor side is 40 ° C., the terminal Bias of the devices 17A, 17B, 17C, 17D, 17EA are collectively set to the environmental temperature of 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. No terminals are connected to both ends of the wire harness 100B, assuming that there is no further heat transfer. However, if a problem such as processing cannot be executed due to the presence of the OPEN terminal on the circuit simulator, a terminating resistor larger than the thermal resistance may be used for GND connection.

Next, in step S204, the calculation of the thermal network method is executed on the personal computer 3 using the circuit simulator for the wire harness thermal 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. 21 and 22 show an example of the temperature distribution of the wire harness 100B displayed on the output device 502. 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 sec has elapsed, and FIG. 22 shows the temperature of the wire harness 100B when the energization time T: 3600 sec has elapsed, as the height of the bar. In other words, the higher the bar, the higher the temperature.

As described above, in the thermal analysis method of the wire harness according to the present embodiment, a plurality of electric wire bundle portions 11A to 11I divided for each branch are equally divided into 1 cm lengths 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 wire bundle portion 11A to 11I of the above is created. A plurality of devices 17A to 17I in which each reference heat equivalent circuit is connected by 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. The calculation of the thermal network method is executed for the wire harness heat equivalent circuit 42 by using a circuit simulator, and the temperature distribution of the wire harness 100B is visualized.

According to the wire harness thermal analysis method, the thermal analyzer, and the program according to the present embodiment, the wire harness 100B is made into a device on the circuit simulator for a plurality of electric wire bundle portions 11A to 11I divided for each branch. 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 wire harness heat equivalent circuit in consideration of 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 partially change it, but by modifying the device, the wire harness It is possible to reduce the man-hours required for modeling and modifying the above. For example, when changing the length of the wire bundle portion corresponding to the device model 17EA of 6 circuits / 50 cm shown in FIG. 19, it is only necessary to rewrite the netlist 16 in spreadsheet software and replace the device model 17EA.

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

[Modified Example of Embodiment 2]
FIG. 23 is a schematic diagram of a reference heat equivalent circuit according to a modified example of the second embodiment. FIG. 24 is a schematic view of a device model corresponding to the electric wire bundle portion of the wire harness according to the modified example of the second embodiment. FIG. 25 is a schematic view of a device model corresponding to the wire harness according to the modified example of the second embodiment. FIG. 26 is a schematic view of a wire harness heat equivalent circuit according to a modified example of the second embodiment.

The method of thermal analysis of the wire harness in the modified example 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 modeled by connecting the reference heat equivalent circuit 51Ea for the length of the electric 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 thermal equivalent circuit 52, the 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 device, and the program of the wire harness according to the modified example of the second embodiment, since each of the plurality of devices 61A to 61I has the ambient temperature of the Bias voltage as a fixed value, the ambient temperature is set for each device. Can be set.

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

Further, in the first and second embodiments and the modified examples, the length for equally dividing the electric wire bundle portions 11, 11A to 11I having a uniform cross-sectional structure into a finite number in the longitudinal direction is set to 1 cm, but the length is limited to this. It's not a thing.

Further, in the second embodiment, the wire harness 100B having a branched structure is divided for each branch, but it may be divided for each cross-sectional structure or for each number of circuits.

Further, in the second embodiment and the modified example, the case where the temperature distribution of the wire harness is displayed on the output device 502 by the display methods as shown in FIGS. 10, 21 and 22 has been described, but the display method is limited to these display methods. It is not something that is done.

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

1 Thermal analyzer 3 Personal computer 5 Input / output device 7,15,16 Netlist 11,11A-11I Wire bundle 11a, 11Ea Wire bundle for 1 cm in length 12A-12I Cross-sectional structure 15a Thermal resistance 15b Heat capacity 15c Heat source 17A to 17I, 61A to 61I Devices 21, 41A to 41I Wire bundle heat equivalent circuit 21a, 41Ea, 51Ea Reference heat equivalent circuit 22, 42, 52 Wire harness heat equivalent circuit 100A, 100B Wire harness 111 Exterior material 112 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 (4)

A method for thermal analysis of wire harnesses that simulates the temperature distribution of wire harnesses mounted on vehicles using a computer.
Of the wire harness, a wire bundle portion having a uniform cross-sectional structure orthogonal to the longitudinal direction is equally divided into a finite number of wire bundle portions having a constant length in the longitudinal direction to form the wire bundle portion having a certain length. The first modeling step of calculating the thermal characteristic parameters by thermo-fluid analysis and modeling the reference thermal equivalent circuit corresponding to the wire bundle portion for a certain length based on the calculated thermal characteristic parameters, and
A wire bundle heat equivalent circuit is created by connecting the reference heat equivalent circuit by the length of the wire bundle portion, and the entire wire harness is supported based on the thermal characteristic parameters constituting the wire bundle heat equivalent circuit. The second modeling step to model the wire harness thermal equivalent circuit,
It comprises a visualization step of performing a thermal network method on the wire harness thermal equivalent circuit to visualize at least one of the temperature distribution and transient temperature rise of the wire harness.
The thermal characteristic parameter includes a thermal resistance value in each heat transfer path between a plurality of members constituting the electric wire bundle portion for a certain length and between each member and the external environment .
The first modeling step further
When the wire harness has a branch structure, the plurality of wire bundles divided for each branch are equally divided into a finite number in the longitudinal direction with a certain length, and each wire bundle for a certain length is provided. Create the reference heat equivalent circuit corresponding to each part,
The second modeling step further
A plurality of the wire bundle heat equivalent circuits in which each reference heat equivalent circuit is connected by the length of each wire bundle portion are created, and the wire harness heat equivalent circuit is formed based on the plurality of wire bundle heat equivalent circuits. Modeled
The second modeling step is
Each of the wire bundle heat equivalent circuits is modeled as a device having terminals for connecting to other wire bundle heat equivalent circuits, and a plurality of the devices are connected to each other via the terminals to connect the wire harness heat. A method for thermal analysis of wire harnesses, which comprises modeling an equivalent circuit. The method for thermal analysis of a wire harness according to claim 1 , wherein the thermal characteristic parameter includes the environmental temperature of the wire harness. A wire harness thermal analyzer that simulates the temperature distribution of a wire harness mounted on a vehicle.
A plurality of electric wire bundles that are divided for each branch of the wire harness and have a uniform cross-sectional structure orthogonal to the longitudinal direction are equally divided into a finite number of constant lengths in the longitudinal direction to have a constant length. A calculation means for calculating the thermal characteristic parameters required for modeling each reference heat equivalent circuit corresponding to each wire bundle portion of a certain length based on each wire bundle portion of the minute.
Create a plurality of wire bundle heat equivalent circuits in which each reference heat equivalent circuit is connected by the length of each wire bundle, and model a wire harness heat equivalent circuit based on the plurality of wire bundle heat equivalent circuits. Processing means to be
A display means for displaying at least one of the temperature distribution and the transient temperature rise of the wire harness from the calculation result of the thermal network method executed for the wire harness thermal equivalent circuit is provided.
The thermal characteristic parameter includes a thermal resistance value in each heat transfer path between a plurality of members constituting the electric wire bundle portion for a certain length and between each member and the external environment .
The calculation means further
When the wire harness has a branch structure, the plurality of wire bundles divided for each branch are equally divided into a finite number in the longitudinal direction with a certain length, and each wire bundle for a certain length is provided. Create the reference heat equivalent circuit corresponding to each part,
The processing means further
A plurality of the wire bundle heat equivalent circuits in which each reference heat equivalent circuit is connected by the length of each wire bundle portion are created, and the wire harness heat equivalent circuit is formed based on the plurality of wire bundle heat equivalent circuits. Modeled
The processing means
Each of the wire bundle heat equivalent circuits is modeled as a device having terminals for connecting to other wire bundle heat equivalent circuits, and a plurality of the devices are connected to each other via the terminals to connect the wire harness heat. A wire harness thermal analyzer characterized by modeling an equivalent circuit. A computer-readable program that performs a method of thermal analysis of a wire harness to simulate the temperature distribution of a wire harness mounted on a vehicle.
A plurality of electric wire bundles that are divided for each branch of the wire harness and have a uniform cross-sectional structure orthogonal to the longitudinal direction are equally divided into a finite number of constant lengths in the longitudinal direction to have a constant length. A calculation function that calculates the thermal characteristic parameters required for modeling each reference heat equivalent circuit corresponding to each wire bundle portion of a certain length based on each wire bundle portion of the minute, and a calculation function.
Create a plurality of wire bundle heat equivalent circuits in which each reference heat equivalent circuit is connected by the length of each wire bundle, and model a wire harness heat equivalent circuit based on the plurality of wire bundle heat equivalent circuits. Processing function and
From the calculation result of the thermal network method executed for the wire harness heat equivalent circuit, a computer is realized with a display function for displaying at least one of the temperature distribution and the transient temperature rise of the wire harness.
The calculation function further
When the wire harness has a branch structure, the plurality of wire bundles divided for each branch are equally divided into a finite number in the longitudinal direction with a certain length, and each wire bundle for a certain length is provided. Create the reference heat equivalent circuit corresponding to each part,
The processing function further
A plurality of the wire bundle heat equivalent circuits in which each reference heat equivalent circuit is connected by the length of each wire bundle portion are created, and the wire harness heat equivalent circuit is formed based on the plurality of wire bundle heat equivalent circuits. Modeled
The processing function
Each of the wire bundle heat equivalent circuits is modeled as a device having terminals for connecting to other wire bundle heat equivalent circuits, and a plurality of the devices are connected to each other via the terminals to connect the wire harness heat. A program that allows a computer to model an equivalent circuit.

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