JP6525075B2 - Cable deformation prediction method - Google Patents

Description

  The present invention relates to a cable deformation prediction method.

  In response to strong demands for global environmental protection and energy saving in recent years, electric vehicles (EVs) and fuel cell vehicles (FCEVs) using electric motors as main power sources are energetically researched and developed. As drive mechanisms for these vehicles, there have been proposed a system in which a conventional engine (internal combustion engine) is simply replaced with an electric motor, and an in-wheel motor system in which an electric motor is disposed in a wheel and driven directly. The in-wheel motor system has attracted attention as a very unique drive mechanism, such as a point that the conventional engine room becomes unnecessary and a point which enables each wheel independent drive.

  In the in-wheel motor system, power is supplied to the motor built in the wheel from the outside through a power cable. The power supply cable is subjected to repeated bending movements as the suspension moves, for example, when the vehicle travels. At this time, it is extremely important that the power supply cable is routed so as not to apply an excessive tensile stress to the power supply cable or contact with surrounding structural members, rotating wheels and the like.

  On the other hand, a method of visualizing the bending state of a plurality of conductor wires constituting a stranded cable is disclosed for a stranded cable to be arranged in a bendable movable part such as a door of an automobile (see Patent Document 1). ).

JP, 2009-266775, A

  In an in-wheel motor electric vehicle, the power cable of the in-wheel motor may come into contact with surrounding structural members unexpectedly. This means that the power supply cable is deformed in a direction out of the bending movement (referred to as out-of-plane deformation) when it is subjected to repeated bending movements accompanying the movement of the suspension.

  Patent Document 1 describes a method for visually grasping a bending state of a conductor wire constituting a cable when the cable is bent at a certain curvature, and a visualization system. The bending state of the conductor wire calculated at this time is obtained by a geometrical calculation formula, and does not take into consideration the stress distribution inside the cable. Since the prediction of the out-of-plane deformation is caused by the stress distribution inside the cable, Patent Document 1 can not cope with the out-of-plane deformation of the problem of the present application.

  Unforeseen contact between the power cable and the surrounding structural member may cause damage to the power cable over time, so sufficient elucidation is necessary.

  The present invention is an invention for solving the above-mentioned problems, and provides a cable deformation prediction method capable of predicting cable deformation in advance at the design stage on the premise of using a cable having a bending rod. The purpose is to

To achieve the above object, the cable deformation prediction method of the present invention, the bending prediction apparatus for predicting a cable deformation in a cable having a habit is, bending of the cable having a habit bending be drawn an arc at least under stress unloaded environment The cable is straightened using an analytical model created by reproducing the shape having the radius of curvature based on the bending radius of the cable, using the bending radius based on the bending radius of the cable required for prediction of deformation based on the ridge. The stress distribution calculation step of calculating the stress distribution in the cable at the time of deformation, the rotation angle setting step of setting the rotation angle around the axis of the cable to determine the installation direction of the cable having a bending weir, the rotation angle stress is distributed and set to the initial state, Cave of calculating the deformation of the cable at the time of deforming the cable according to the load condition A deformed state calculating step, characterized by having a. Other aspects of the invention are described in the embodiments described below.

  According to the present invention, the deformation of the cable can be predicted in advance at the design stage on the premise of using a cable having a bending weir.

It is a schematic diagram which shows the example of a structure and cable layout around an in-wheel motor when the inner side of a wheel is seen from the side direction of a vehicle body. It is a schematic diagram which shows the example of a structure and cable layout when the inner side of a wheel is seen from the upper surface direction of the vehicle body of FIG. It is a cross-sectional schematic diagram which shows an example of the cable used for a power supply cable. It is a block diagram showing a prediction device for predicting out-of-plane deformation and its variation. It is a flowchart which shows the cable out-of-plane deformation | transformation and the prediction method of the dispersion | variation. It is an explanatory view showing an example of modeling. It is explanatory drawing which shows the installation direction with respect to the curl of a cable.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. First, a structural example around the in-wheel motor and a cable layout will be described with reference to FIGS. 1 and 2.

(Cable layout)
FIG. 1 is a schematic view showing an example of a structure around an in-wheel motor and a cable layout when the inside of a wheel is viewed from the side direction of a vehicle body. FIG. 2 is a schematic view showing an example of a structure and a cable layout when the inside of the wheel is viewed from the upper surface direction of the vehicle body of FIG. The in-wheel motor 30 is fixed to the suspension arm 31 together with the suspension 32, and the motor rotation shaft is disposed so as to be the rotation shaft of the wheel 35.

  A three-phase alternating current motor is usually used because the in-wheel motor 30 simultaneously requires a reduction in size for installation in a space restricted by the wheel 35 and a high output for traveling the vehicle. . Therefore, a plurality of power supply cables 20 (for example, power supply cables 20 a to 20 c) are connected to the in-wheel motor 30 via the connection terminals 21 and the terminal block 33. From such a situation, the power cable 20 for supplying power to the in-wheel motor 30 is necessarily routed in a narrow space.

  Furthermore, the power supply cable 20 is subjected to repeated bending movements as the suspension 32 moves, for example, when the vehicle is traveling. For example, the bending movement is received in the operating direction of the suspension 32 in FIG. At this time, the power cable 20 is routed so as not to apply an excessive tensile stress to the power cable 20 or contact with the surrounding structural members (for example, the suspension 32) and the rotating wheel 35 (including the tire). It is extremely important to be

  As described above in the problem to be solved, in the in-wheel motor type electric vehicle, the power cable 20 of the in-wheel motor 30 may come into contact with surrounding structural members unexpectedly. This is because, when the power supply cable 20 is subjected to repeated bending movements as the suspension 32 moves, deformation occurs in the direction out of the bending movement plane (in the xy plane of FIG. 1). Means to For example, out-of-plane deformation occurs, which is deformation in a direction indicated by an arrow in FIG.

  As a result of various investigations while replacing the power supply cable 20, the appearance and degree of the out-of-plane deformation were different for each power supply cable 20, and a consistent tendency was not found initially. In other words, it was thought that the prediction was difficult because the factors of the out-of-plane deformation of the power supply cable 20 and the variation thereof were unknown, but it was solved based on the following basic idea.

(Basic thought of the present invention)
The present inventors configure the power supply cable 20 in order to clarify the factor that the appearance and degree of the out-of-plane deformation of the power supply cable 20 largely vary from one power supply cable 20 to another when the bending motion is imposed on the power supply cable 20. The investigation went back to the manufacture of the electric wire.

  Since cables are generally manufactured in a long length, they are usually stored wound on a bobbin / drum until just before they become final products. When the cable is cut out from the bobbin / drum to a predetermined length in order to manufacture the power supply cable 20 by end processing, the cut-out cable may still have a curl. It is said that the curling of such a cable is due to the viscoelasticity of the insulating material / sheath material made of resin. Also, it is believed that the curling of the cable also depends on the material of the insulating material / sheath material, the storage period of the manufactured cable, and the diameter of the bobbin / drum on which the cable is wound up.

  Therefore, on the premise that a cable having a curl is used, the inventors investigated and studied the relationship between the curl and the appearance and degree of the out-of-plane deformation of the power supply cable 20 in more detail. As a result, it has been found that the appearance and degree of the out-of-plane deformation of the power supply cable 20 is strongly influenced by the relationship between the winding direction of the cable used and the direction of the bending movement imposed on the power supply cable 20. The present invention is based on the above findings.

(Cable structure)
FIG. 3 is a schematic cross-sectional view showing an example of a cable used for a power supply cable. The cable 10 includes a cable 10 in which an insulating layer 13, a reinforcing braided layer 14 and a resin sheath 15 are sequentially formed on the outer periphery of a central conductor 12 (conductor), and a connection terminal 21 formed at the end of the cable 10 in the longitudinal direction. See FIG. 1). The cable 10 has a curl that attempts to draw an arc under stress free environment.

  The cross-sectional structure of the cable 10 is not limited to that shown in FIG. 3 and is not limited to the other configuration as long as it has at least the central conductor 12 and the resin sheath 15 of the outermost layer. Also, in the present embodiment, the stress-free environment refers to a plate on which surface friction is made as small as possible (for example, on a surface-finished polytetrafluoroethylene (PTFE) plate or a surface-finished ice plate) ), The cable 10 is defined as a quiet environment.

  In the present embodiment, the central conductor 12 is preferably a stranded wire in which a plurality of strands 11 are twisted together. Generally, a stranded wire conductor has an advantage of high bending resistance because each strand is uniformly stressed during bending movement. In FIG. 3, although a 29-core twisted wire is drawn, it is of course not limited thereto. Moreover, the strands 11 may themselves be made of a thinner strand of strands.

  The material and thickness of the insulating layer 13, the reinforcing braided layer 14 and the resin sheath 15 are not particularly limited, and an electrical device to be connected to the power cable 20 (see FIG. 1) (for example, in-wheel motor 30) It may be appropriately selected according to the specifications of For example, a polyethylene (PE) layer (0.5 mm in thickness) is used as the insulating layer 13 for the central conductor 12 (diameter 3.4 mm) as the cable 10, and a polyethylene terephthalate (PET) fiber braided as the reinforcing braided layer 14 It is possible to use an ethylene propylene diene rubber (EPDM) layer (thickness 0.8 mm) as the resin sheath 15 using the layer (thickness 1.0 mm).

(Configuration of prediction device)
FIG. 4 is a block diagram showing a prediction apparatus for predicting out-of-plane deformation and its variation. The prediction apparatus 100 includes, as shown in FIG. 4, an input device 41 including a keyboard and a mouse, an output device 42 including a display and a printer, and a storage unit 43 including a hard disk for storing various information. A process for predicting the out-of-plane deformation of the cable 10 and the variation thereof based on the cable stiffness measurement unit 44 for measuring the stiffness of the cable 10 and various data input by the input device 41 and the cable stiffness measurement unit 44 And a data processing unit 50 for performing the

  The input device 41 receives shape information of the cable 10 and parameters required for calculation. The output device 42 outputs the calculation result by the data processing unit 50.

  The data processing unit 50 calculates equivalent material physical properties from the stress-strain curve obtained by the control unit 51 that comprehensively controls each function of the data processing unit 50 and the cable stiffness measurement unit 44. A finite element analysis is performed using the derivation unit 52, an analysis model generation unit 53 for generating an input file for finite element analysis of the cable 10 from various parameters input by the input device 41, and the cable using the generated input file. A deformation state calculation unit 54 that calculates 10 deformation states, and an output calculation unit 55 that calculates calculation results of the deformation state of the cable 10, out-of-plane deformation variation, stress and the like, and outputs the calculation result to the output device 42.

(Forecasting method)
Next, specific processing contents performed by the prediction device 100 will be described based on FIGS. 5 and 6. FIG. 5 is a flowchart showing an out-of-plane deformation and its variation prediction method. FIG. 6 is an explanatory view showing an example of modeling. Refer to FIG. 3 and FIG. 4 as appropriate.

(S101): The data processing unit 50 receives input of various input parameters necessary for deriving the equivalent material physical properties of the cable 10 and predicting the out-of-plane deformation variation. The input is performed by the input device 41 and recorded in the storage unit 43. Input parameters are length of cable 10, radius of cable 10, stranding method of strand 11, radius of strand 11, number of strands 11, stranding pitch of strand 11, curvature radius of bending ridge of cable 10, installation It comprises the step size of the direction (rotational step Δθ) and the load condition. As the load conditions, selection of the type of load (L-curve bending or S-curve bending, etc.) and the size of the load at that time (curvature radius, geometrical positional relationship, etc.) are input. The installation direction will be described in S105.

(S102): The equivalent material physical property deriving unit 52 derives equivalent physical property values including all of the constituent materials such as the central conductor 12 and the resin sheath 15 shown in FIG. Replace with In addition, it is preferable that the conductor portion be modeled as a truss element that is only responsible for the axial force, and be embedded in the analysis model as a homogeneous body. The equivalent material physical properties of the homogeneous body portion are derived from the stress-strain curve obtained by the cable stiffness measurement unit 44. The stress-strain curve of the cable 10 can be obtained, for example, by a bending test such as three-point bending.

  In the equivalent material physical property derivation unit 52, a finite element analysis model of the cable 10 to be measured by the cable stiffness measurement unit 44 is created by the analysis model creation unit 53, and a stress-strain curve is calculated using virtual physical property values. calculate. It is equivalent by evaluating the difference between the stress-strain curve obtained by measurement and the stress-strain curve obtained by calculation and searching for the material property with the smallest difference among the specified physical range and the number of repetitions. Calculate the material properties. As search algorithm, exhaustive search, minimum gradient method, genetic algorithm method and the like can be used.

  As a material model, for example, it is possible to make an area excluding the conductor part of the cable 10 an elastic-plastic body and approximate the conductor part to an elastic body.

(S103): The analysis model creation unit 53 analyzes the finite element analysis model of the cable 10 having a bending weir, the radius of the input cable 10, the length of the cable 10, the curvature radius of the bending weir, the twist method of the wire 11 , The radius of the wire 11, the number of the wires 11, and the twist pitch of the wires 11. A finite element analysis model of the cable 10 having a bending weir can be created by the following procedure.

  First, the analysis model creation unit 53 creates a finite element analysis model of the linear cable 10 according to the input parameter (Fig. 6 (a) linear shape creation). Next, the linear finite element analysis model is deformed in accordance with the curvature radius of the bending ridge input by the deformation state calculation unit 54 (deformation by the curvature radius of the bending ridge in FIG. 6B). Next, only the shape information obtained at this time (except information such as stress) is handed over to the next step as a finite element analysis model (only the shape shown in FIG. 6C is handed over).

(S104): The deformation state calculation unit 54 linearly deforms the finite element analysis model created in S103, and calculates the stress distribution inside the cable (FIG. 6 (d) linear deformation to calculate stress distribution).

(S105): The deformation state calculation unit 54 sets a rotation angle around the axis of the cable 10 in order to determine the installation direction of the bending rod, and sets a cable model (finite element analysis model) deformed in a straight line. It arrange | positions by the rotation angle (The initial value is installation angle (theta) = 0 degree) (installation by the installation angle (theta) of FIG.6 (e)).

  In the present embodiment, the cable 10 including the conductor and the resin sheath 15 covering the conductor is horizontally disposed, and the vertical surface along the axial center of the cable 10 is used as a reference surface to bend the cable 10 in the vertical direction. . The rotation angle around the axis of the cable 10 with respect to the reference plane is set. Although the installation angle θ is 0 ° as an initial value, the calculation of S106 may be started from an arbitrary installation angle.

(S106): The deformation state calculation unit 54 deforms the cable 10 according to the input load condition to calculate the deformation state and the out-of-plane deformation amount of the cable 10 (FIG. 6 (f) deformation under the designated load condition, Fig. 6 (g) Calculate the out-of-plane deformation amount and the cable deformation state).

(S107): The deformation state calculation unit 54 determines whether or not the installation angle θ indicating the installation direction has reached the upper limit value θmax (= 360 °). If the upper limit value θmax has not been reached (S107, No), the process proceeds to S108, and if the upper limit value θmax has been reached (S107, Yes), the process proceeds to S109. The upper limit value θmax may be a predetermined value for evaluating out-of-plane deformation.

(S108): The deformation state calculation unit 54 increases the installation angle θ by the specified step width Δθ, updates the value, and returns to S105.

(S109): The output calculation unit 55 calculates the variation width of the out-of-plane deformation amount with respect to the assumed load path and the deformation state, and displays them on the output device 42 (FIG. 6 (g)).

  In addition, when the difference between the finite element analysis model created in S102 and the finite element analysis model shown in FIG. 6A in S103 is described, only the length of the cable 10 and the load condition are different. In the finite element analysis model created in S102, modeling of the bending weir shown in FIG. 6 (b) is not necessary. As a load condition, for example, in the case of three-point bending, it is preferable to give time histories of load, displacement, and the like. Therefore, the cable length of the finite element analysis model of FIG. 6A may be appropriately changed and used for the finite element analysis model created in S102.

(Confirmation of operation and effect of the embodiment)
In order to confirm the effect of this embodiment, the power supply cable 20 shown below was produced, and the amount of out-of-plane deformation was measured to confirm the prediction accuracy.

(How to make a power cable)
First, the cable 10 shown in FIG. 3 was produced. The produced power cable 20 has a PE layer (0.5 mm thick) as the insulating layer 13 and an EPDM layer (thickness 0) as the outermost resin sheath 15 on the outer periphery of the central conductor 12 (diameter 3.4 mm, 29 cores) A cable 10 (having an outer diameter of 8.0 mm), in which 8 mm) were sequentially formed, was prepared.

  Next, in order to produce the power supply cable 20, the cable 10 was cut out from the bobbin with a length such that the distance between the connection terminals 21 was 160 mm. The cable 10 immediately after it was cut out had a curl with a radius of curvature of about 100 mm due to the effect of being wound and stored around the bobbin. Finally, both ends of the cable 10 were subjected to end processing, and the connection terminal 21 was attached to fabricate the power supply cable 20.

(Outside deformation measurement method)
FIG. 7 is an explanatory view showing the installation direction of the cable with respect to the curl. FIG. 7 is an image diagram for understanding the relationship between the winding direction of the cable 10 and a plane (xy plane) which imposes an L-shaped bending on the cable. The method of measuring the amount of out-of-plane deformation of the power cable 20 will be described with reference to FIG.

  The power supply cable 20 is in a state in which one end (cable end A) is fixed to the origin O. Then, the other end (cable end B) of the power supply cable 20 is free (for example, not pinched by a chuck etc.), and it is assumed that the curling of the cable 10 appears clearly. (Specifically, the shape of the power supply cables 201 to 203) is shown.

  More specifically, the power supply cable 201 shows the case where the winding direction of the cable 10 is in the xy plane and the free cable end B is in the positive region of the y axis (y ′ ′ axis). (Hereinafter, this is defined as installation direction 0 °.) The power cable 202 has the winding direction of the cable 10 in the xz plane and the free cable end B is positive in the z axis (z ′ ′ axis). (In the following, this is defined as an installation direction of 90 °). The power supply cable 203 shows the case where the winding direction of the cable 10 is in the xz plane and the free cable end B is in the negative region of the z axis (z ′ ′ axis) (hereinafter, this is installed) Defined as direction 270 °).

  In the measurement of the amount of out-of-plane deformation, the cable end B is once moved on the x axis (x-x 'axis) with the cable end B sandwiched, and then the cable end B is moved in the xy plane to move the power cable 201, L-shaped bending was imposed on 202 and 203. At this time, the maximum amount of deformation of the cable 10 of the power cables 201, 202 and 203 in the out-of-plane direction (z direction) was measured.

  In FIG. 7, the origin O corresponds to, for example, the connection terminal 21 of FIG. 1, and a cable 10 of a predetermined length from there is assumed. Actually, S-shaped bending is performed as shown in FIG. 1, but in the present embodiment, L-shaped bending which is a more basic deformation mode is targeted. Since S-shaped bending is a combination of L-shaped bending, the same effect as that of the present embodiment can be obtained in S-shaped bending as well.

  Table 1 is a table showing the effects of the embodiment, and is a table showing the prediction results and the experimental results of the out-of-plane deformation when bending in an L-shape in the installation direction of 0 °, 90 ° and 270 °. is there. Table 1 shows the comparison result of the measured value and the predicted value according to the present invention (the comparison result of the measured value of the amount of out-of-plane deformation and the predicted value).

  The cable out-of-plane deformation prediction apparatus 100 according to the present embodiment arranges the cable 10 including the conductor and the resin sheath 15 covering the conductor horizontally and sets the vertical plane along the axial center of the cable 10 as a reference surface. An input device 41 for receiving input parameters necessary for the prediction of out-of-plane deformation when bending a cable 10 having a curl to draw an arc under no load environment in the vertical direction, and equivalent material physical properties of the entire cable 10 Based on the equivalent material physical property deriving unit 52 which derives the value from the measured stress-strain curve and the equivalent material physical property value of the cable 10 which is derived, the shape having the curvature radius of the bending ridge input from the input device 41 is reproduced 6 (a) to (c), the cable 10 is deformed in a straight line, and the stress distribution in the cable 10 is calculated. S104, FIG. 6D, setting an angle of rotation around the axis of the cable 10 for determining the installation direction of the bending rod (S105, FIG. 6E), the analysis model generation unit 53, and the calculated stress With the distribution and the set rotation angle as the initial state, the cable 10 is deformed according to the load condition input from the input device 41, and the deformation state and the out-of-plane deformation amount of the cable 10 are calculated (S106, FIG. )) And an output operation unit 55 for outputting the calculation result of the deformation state of the cable 10 and the out-of-plane deformation amount (S109, FIG. 6 (g)) to the output device 42.

  As described above, the prediction device according to the present invention can predict with high accuracy the out-of-plane deformation amount at the time of cable bending and the variation width thereof, which has been difficult to predict so far. As a result, since it is possible to know in advance the clearance value required for cable routing, it is possible to minimize unexpected cable contact.

  The above-described embodiment is specifically described in order to help the understanding of the present invention, and the present invention is not limited to including all the described configurations. For example, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Furthermore, with respect to a part of the configuration of each embodiment, it is possible to delete, add to other configurations, and add other configurations. Further, the scope of application of the present invention is not particularly limited to cables for in-wheel motors, and is applicable to all types of cables for bending applications such as other bending cables for automobiles and cables for industrial robots.

10 cable 11 wire 12 center conductor (conductor)
13 Insulating layer 14 Reinforcement braided layer 15 Resin sheath 20, 20a, 20b, 20c, 201, 202, 203 Power cable 21 Connection terminal 30 In-wheel motor 31 Suspension arm 32 Suspension 33 Terminal block 35 Wheel 41 Input device 42 Output device 43 Memory Unit 44 Cable stiffness measurement unit 50 Data processing unit 51 Control unit 52 Equivalent material physical property derivation unit 53 Analysis model creation unit 54 Deformation state calculation unit 55 Output operation unit 100 Prediction device

Claims (4)

A prediction device for predicting cable deformation in a cable having a bending rod is
Using the radius of curvature based on the bending habit of the cable, which is necessary for the prediction of the deformation based on the bending habit of the cable having the bending habit trying to draw an arc at least under a stress-free environment , Stress distribution calculation step of calculating stress distribution in the cable when the cable is linearly deformed using an analysis model created by reproducing a shape having a curvature radius based on the stress distribution calculation process;
A rotation angle setting step of setting a rotation angle around an axis of the cable for determining the installation direction of the cable having the bending rod;
A cable deformation state calculation step of taking the calculated stress distribution and the set rotation angle as an initial state, and calculating a deformation state of the cable when the cable is deformed according to a load condition. Cable deformation prediction method characterized by The load conditions are determined by the type of load and the size of the load at that time,
The cable deformation prediction method according to claim 1, characterized in that: The analysis model is created from the radius and length of the cable, the radius of curvature of the bending ridge, the stranding method of the strands, the radius of the strands, the number of strands, and the stranding pitch of the strands.
The cable deformation prediction method according to claim 1 or 2, characterized in that: Said stress stress calculated distribution by distribution calculation step, the cable deformation according to any one of claims 1 to 3, characterized in that it is calculated based on only the shape information before deformation the cable in a straight line Forecasting method.

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