JP2016197564A - Cable structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cable structure securing safety of a system that repeats relative movement, while suppressing a size up and cost up of a strong electric cable.SOLUTION: A motor cable 6, which is a strong electric cable, is used for an in-wheel motor system where an in-wheel motor 4 repeats relative movement with respect to an inverter 5, and electrically connects between the inverter 5 and the in-wheel motor 4. The motor cable 6 is configure to be a multilayer structure including a plurality of layers 61, 62, 63, and 64 coaxially arranged. And in all the layers 61, 62, 63, and 64 constituting the motor cable 6, flexural durability determined by an amount of relative movement and the number of times of repeated fatigue is secured to a specific value or more and in addition to the outermost layer 64, the insulation layer 62 as a weakest part with a weaker flexural durability than the outermost layer 64 is provided.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a cable structure of a high-voltage cable that electrically connects between a power supply unit and a drive unit that repeat relative movement.

  2. Description of the Related Art Conventionally, as an electric cable, a cable composed of a plurality of covered electric wires, an insulating layer having a hollow portion in which the plurality of covered electric wires are fixed to the inner periphery, and a sheath (outermost layer) covering the outer periphery is known (for example, , See Patent Document 1).

Japanese Patent No. 4821983

  However, in the conventional electric cable, it has not been considered until the final breakage, and at the end, the electric wire (copper wire) may break, and the broken copper wire may break through the sheath and be exposed to the surface. There was a problem that there was. In addition, when the durability is increased by providing a hollow portion or by increasing the thickness of the sheath, the current density is lowered. Therefore, there is a problem that the size and cost are increased in order to secure a necessary current.

  The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a cable structure that ensures the safety of a system that repeats relative movement while suppressing an increase in size and cost of a high-power cable.

In order to achieve the above object, the high power cable of the present invention is used in a system in which the drive unit repeats relative movement with respect to the power supply unit, and electrically connects the power supply unit and the drive unit.
The high-voltage cable has a multilayer structure having a plurality of layers in a coaxial arrangement.
In addition, the bending durability determined by the relative movement amount and the number of times is ensured to a certain value or more in all layers constituting the high-power cable, and the weakest portion having a bending durability weaker than the outermost layer is provided in addition to the outermost layer.

Therefore, the high-power cable has a multi-layer structure, and the bending durability determined by the relative movement amount and the number of times is secured to a certain value or more in all layers constituting the high-power cable, and the bending durability is higher than the outermost layer in addition to the outermost layer. The weakest part is weak.
That is, since the high-voltage cable has a multi-layer structure having a plurality of layers arranged coaxially, the increase in size and cost can be suppressed even when the conductor layer has a sufficient cross-sectional area to ensure the necessary current. Furthermore, the weakest part having a lower bending durability than the outermost layer is provided from the layers other than the outermost layer, that is, the part where the degree of damage is maximized at the time of design is determined. Therefore, even when the usage exceeds the service life, it is possible to safely stop the function or detect the abnormality by the weakest part, so that the safety of the system that repeats the relative movement is ensured.
As a result, it is possible to ensure the safety of the system that repeats relative movement while suppressing the increase in size and cost of the high-voltage cable.

It is a top view which shows the rear part of the in-wheel motor vehicle provided with the motor cable to which the cable structure of Example 1 was applied. It is a front view which shows the rear part of the in-wheel motor vehicle provided with the motor cable to which the cable structure of Example 1 was applied. It is sectional drawing which shows the motor cable to which the cable structure of Example 1 was applied. It is a circuit diagram which shows the electrical leakage detection means of the motor cable to which the cable structure of Example 1 was applied. It is explanatory drawing which shows the change state of the motor position and cable stress by the movement (swing) of the in-hole motor of the motor cable to which the cable structure of Example 1 is applied. It is a linear characteristic figure which shows the conductor layer stress characteristic, insulating layer stress characteristic, and outermost layer stress characteristic in case the relationship between the motor position of a motor cable and cable stress is linear. It is a nonlinear characteristic figure which shows the conductor layer stress characteristic, insulation layer stress characteristic, and outermost layer stress characteristic in case the relationship between the motor position of a motor cable and cable stress is nonlinear. Strength of motor cable with conductor layer / insulation layer / outermost layer showing the relationship between the life of each layer and the stress amplitude, and the damage degree of all layers (conductor layer, insulation layer, shield layer, outermost layer) and the strength relationship of each layer FIG. It is a nonlinear characteristic figure which shows the relationship characteristic (conductor layer stress characteristic / shield layer stress characteristic) of the motor position of a metal layer, and cable stress in the motor cable to which the cable structure of Example 1 was applied. FIG. 3 is a bearing diagram showing the relationship between the life of a metal layer (conductor layer / shield layer) and the stress amplitude in a motor cable to which the cable structure of Example 1 is applied. It is a nonlinear characteristic figure which shows the relationship characteristic (outermost layer plastic strain characteristic / insulating layer plastic strain characteristic) of the motor position of a resin layer, and plastic strain in the motor cable to which the cable structure of Example 1 is applied. It is a strength line figure showing the relation between the life of a resin layer (outermost layer / insulating layer) and the plastic strain amplitude in a motor cable to which the cable structure of Example 1 is applied. It is the intensity | strength relationship figure between each layer which shows the damage degree of all the layers (a conductor layer, an insulating layer, a shield layer, outermost layer) and the intensity | strength relationship for every layer in the motor cable to which the cable structure of Example 1 was applied.

  Hereinafter, the best mode for realizing the cable structure of the present invention will be described based on Example 1 shown in the drawings.

First, the configuration will be described.
The cable structure according to the first embodiment is applied to a three-phase motor cable that electrically connects an inverter and an in-wheel motor in a rear-wheel drive in-wheel motor vehicle. Hereinafter, the configuration of the cable structure in the first embodiment will be described by being divided into “overall configuration”, “cable configuration”, and “determination configuration of strength relationship for each layer”.

[overall structure]
1 and 2 are a plan view and a front view showing a rear part of an in-wheel motor vehicle equipped with a motor cable to which the cable structure of the first embodiment is applied. The overall configuration will be described below with reference to FIGS.

  As shown in FIGS. 1 and 2, the in-wheel motor vehicle includes a suspension member 1, left and right rear wheel tires 2L and 2R, left and right rear wheel wheels 3L and 3R, and left and right in-wheel motors 4L and 4R. And an inverter 5 and left and right three-phase motor cables 6L and 6R are provided at the rear of the vehicle.

  The suspension member 1 is attached as a vehicle body side member of the left and right suspension devices 7L and 7R for suspending left and right rear wheel units (a general term for left and right rear wheel tires + wheels + motors) on the vehicle body. As shown in FIG. 1, the suspension member 1 is a square member disposed in a central region sandwiched between left and right rear wheel tires 2L and 2R, and a total of four mounting members 11 with respect to the vehicle body main frame. It is elastically supported via. The left and right suspension devices 7L and 7R include a lower link, an upper link, a shock absorber, a coil spring, and the like.

  The left and right rear wheel tires 2L, 2R are mounted on the outer peripheral positions of the left and right rear wheel wheels 3L, 3R, respectively. A left in-wheel motor 4L that drives the left rear wheel tire 2L is attached to the left rear wheel 3L in a state where at least a part thereof is disposed in the wheel inner space. A right in-wheel motor 4R that drives the right rear wheel tire 2R is attached to the right rear wheel 3R in a state where at least a part thereof is disposed in the wheel inner space.

  As shown in FIGS. 1 and 2, the inverter 5 is an example of a power supply unit attached to the upper surface on the vehicle front side of the suspension member 1. The inverter 5 is driven by converting high voltage direct current from a battery (not shown) into three-phase alternating current during powering and applying it to the left in-wheel motor 4L and the right in-wheel motor 4R. Moreover, the inverter 5 converts the three-phase alternating current from the left in-wheel motor 4L and the right in-wheel motor 4R into direct current and charges a battery (not shown) during regeneration. The battery is disposed at a position below the center of the vehicle body floor, and a battery module, a junction box, and the like are installed inside the case.

  The left three-phase motor cable 6L is a cable for electrically connecting the inverter 5 and the left in-wheel motor 4L, and the cable length is a length obtained by adding a margin length to the linear distance between the two connecting portions. As shown in FIG. 2, it is bent slightly downward. The left three-phase motor cable 6L includes a U-phase cable 6LU (vehicle rear position), a V-phase cable 6LV (intermediate position), and a W-phase cable 6LW (vehicle front position) independently. . Further, the inverter 5 and the left in-wheel motor 4L are connected by a ground bonding cable 6LE in parallel with the left three-phase motor cable 6L.

  The right three-phase motor cable 6R is a cable for electrically connecting the inverter 5 and the right in-wheel motor 4R, and the cable length is a length obtained by adding a margin length to the linear distance between the two connecting portions. As shown in FIG. 2, it is bent slightly downward. The right three-phase motor cable 6R includes a U-phase cable 6RU (vehicle rear position), a V-phase cable 6RV (intermediate position), and a W-phase cable 6RW (vehicle front position) independently. . Further, the inverter 5 and the right in-wheel motor 4R are connected by a grounding bonding cable 6RE in parallel with the right three-phase motor cable 6R. That is, the left three-phase motor cable 6L and the right three-phase motor cable 6R are symmetrically arranged with the inverter 5 interposed therebetween.

[Cable configuration]
FIG. 3 is a sectional view showing a motor cable to which the cable structure of the first embodiment is applied, and FIG. 4 is a schematic view showing a leakage detecting means of the three-phase motor cable. Hereinafter, the cable configuration will be described with reference to FIGS. 3 and 4.

  As shown in FIGS. 1 and 2, the cable structure of the first embodiment is applied to an in-wheel motor system in which left and right in-wheel motors 4L and 4R (drive unit) repeat relative movement with respect to an inverter 5 (power source unit). Yes. And the cable structure by the multilayer structure shown in FIG. 3 is employ | adopted as the high electric cable which electrically connects between the inverter 5 and the left-right in-wheel motor 4L, 4R. That is, the U-phase cable 6LU, the V-phase cable 6LV, and the W-phase cable 6LW that constitute the left three-phase motor cable 6L, and the U-phase cable 6RU, the V-phase cable 6RV, and the W-phase cable 6RW that constitute the right three-phase motor cable 6R. It is adopted for each cable. Hereinafter, these cables are collectively referred to as “motor cable 6 (high power cable)”.

  As shown in FIG. 3, the motor cable 6 includes a conductor layer 61, an insulating layer 62, a shield layer 63, and an outermost layer 64. These layers 61, 62, 63, and 64 are coaxially arranged. It has a multi-layer structure (coaxial cable structure).

  The said conductor layer 61 is provided in the cable center axis position, for example, is comprised by twisting a copper wire to a fixed direction and making it a copper wire bundle. The diameter of the copper wire and the number of copper wires constituting the conductor layer 61 are set to a diameter and a number sufficient to pass a necessary current.

  The insulating layer 62 is disposed between the conductor layer 61 and the shield layer 63, and is configured, for example, by covering the outer periphery of the conductor layer 61 with an insulating resin. As the material of the insulating layer 62, a resin material having insulation and elasticity that ensures insulation between the conductor layer 61 and the shield layer 63 even when the motor cable 6 is bent and deformed is used.

  The shield layer 63 is disposed between the insulating layer 62 and the outermost layer 64, and is composed of, for example, a laterally wound shield in which copper or aluminum conductor wires are twisted in a certain direction or a braided shield in which conductor wires are knitted. . The shield layer 63 covers the insulating layer 62 to ensure the function of blocking the influence of noise from the outside and the generation of noise from the inside (conductor layer 61).

  The outermost layer 64 is called a “sheath”, and is configured by covering the outer periphery of the shield layer 63 with a flexible resin. The outermost layer 64 is made of a resin material that is durable enough not to be damaged or damaged by interference with peripheral members.

  Between the conductor layer 61 and the shield layer 63, as shown in FIG. 4, a potential difference sensor 8 is provided as a leakage detecting means. The potential difference sensor 8 is a sensor that monitors a potential difference between the leakage detection line 9 having one end connected to the shield layer 63 and the ground bonding cables 6LE and 6RE. If there is no leakage between the conductor layer 61 and the shield layer 63, a potential difference occurs. However, if there is a leakage, the potential difference becomes 0 (zero) due to a short circuit between the conductor layer 61 and the shield layer 63. The shield layer 63 is connected to the ground via the vehicle body. On the other hand, the strong electric system is in a state where it floats while being electrically isolated from the vehicle body, the shield layer 63, and the ground.

[Determination structure of strength relationship for each layer]
In the motor cable 6, the bending durability determined by the relative movement amount and the number of times is secured to a certain value or more in all layers of the conductor layer 61, the insulating layer 62, the shield layer 63 and the outermost layer 64. At the same time, the insulating layer 62 is the weakest part of the layers other than the outermost layer 64 (the conductor layer 61, the insulating layer 62, and the shield layer 63) that has a lower bending durability than the outermost layer 64.

  In determining the bending durability of each of the layers 61, 62, 63, 64, the resistance line SN against repeated fatigue of each of the layers 61, 62, 63, 64 is used. Each layer 61, 62, 63, obtained by dividing the market input number Na (reference life number) converted to the maximum stroke as the number of repeated fatigue times by the life number Nf (design life number) of each layer for repeated fatigue. It is determined by a damage degree D of 64. That is, if the lifetime Nf of each layer 61, 62, 63, 64 is designed to match the market input number Na, D = 1, and if it is designed to exceed the market input number Na, D <1.

  Here, among the layers 61, 62, 63, and 64 constituting the motor cable 6, the insulating layer 62 and the outermost layer 64 made of an organic substance (resin) use a load bearing line SN having a plastic strain component as a load. On the other hand, in the conductor layer 61 and the shield layer 63 made of an inorganic substance (metal), a load bearing line SN with a stress component or a total strain component as a load is used. Furthermore, with respect to the insulating layer 62, the load-bearing line SN whose lifetime is the failure state in which leakage is detected is used, and the other conductor layer 61, the shield layer 63, and the outermost layer 64 have a failure in which the copper wire of the conductor layer 61 is exposed to the outside. The load bearing line SN whose life is the state is used.

  That is, to ensure that the bending durability of all the layers 61, 62, 63, 64 is a certain value or more, the damage degree D is calculated to be 1 or less in all the layers 61, 62, 63, 64. Design. In addition, the insulating layer 62 is considered to be the weakest portion weaker than the outermost layer 64 in bending durability. Among all the layers 61, 62, 63, 64, the damage degree D of the insulating layer 62 is maximized (others). It is calculated and designed so as to be larger than the layers 61, 63 and 64 and closest to D = 1.

Next, the operation will be described.
The operation in the cable structure of the first embodiment will be described by being divided into “determination of strength relationship for each layer” and “characteristic operation of motor cable”.

[Determination of strength relationship for each layer]
Hereinafter, based on FIG. 5 to FIG. 13, the action of determining the strength relationship for each layer on how the damage level D of each layer 61, 62, 63, 64 is determined will be described in detail.
The left and right rear wheel wheels 3L and 3R are collectively referred to as “rear wheel wheel 3”, and the left and right in-wheel motors 4L and 4R are collectively referred to as “in-wheel motor 4”. Further, when the stress generated in each layer is σ1 to σ4 and the resistance lines against repeated fatigue of each layer are SN1 to SN4, the conductor layer 61 (σ3, SN3), the insulating layer 62 (σ2, SN2), the shield layer 63 ( σ4, SN4) and outermost layer 64 (σ1, SN1) (see FIG. 3).

First, FIG. 5 shows a change state of the motor position δ and the cable stress σ (stress generated in the cable) due to the movement (swing) of the in-wheel motor 4 of the motor cable 6 to which the cable structure of the first embodiment is applied. Since the rear wheel 3 repeats the suspension stroke on the bounce side and the rebound side according to the road surface input or the like during traveling as described above, the in-wheel motor 4 attached to the rear wheel 3 also moves with the stroke. Move (perpendicular). Therefore, the motor cable 6 having one end connected to the inverter 5 and the other end connected to the in-wheel motor 4 is bent and deformed. For example, the arc-shaped cable bends as the in-wheel motor 4 moves downward. The radius of curvature of the part decreases and the stress increases.
Therefore, when the motor position δ is the lowest stroke position δmin, the cable stress σ becomes the maximum stress σmax, and when the motor position δ is the highest stroke position δmax, the cable stress σ becomes the minimum stress σmin.

  FIG. 6 shows an example of the conductor layer stress characteristic σ3, the insulating layer stress characteristic σ2, and the outermost layer stress characteristic σ1 when the relationship between the motor position δ and the cable stress σ is linear. FIG. 7 shows an example of the conductor layer stress characteristic σ3, the insulating layer stress characteristic σ2, and the outermost layer stress characteristic σ1 when the relationship between the motor position δ and the cable stress σ is nonlinear. That is, regardless of the linear characteristic or the non-linear characteristic, the local displacement due to the conductor layer stress characteristic σ3 due to the conductor layer 61 at the axial center position is small in the motor cable 6, and then the insulation layer 62 is the next highest. As in the outer layer 64, the local displacement increases toward the outer peripheral side. The characteristic feature is that the amount of deformation increases as the layer moves toward the outer peripheral side. The stress is determined by the Young's modulus of the material and the locally applied displacement.

For example, assuming a motor cable 6 having a conductor layer 61, an insulating layer 62, and an outermost layer 64, the action of determining the strength relationship for each layer based on the load bearing diagram showing the relationship between the life of each layer and the stress amplitude shown in FIG. Will be explained.
The vertical axis in FIG. 8 is the stress amplitude Δσ, and the stress amplitudes Δσ1, Δσ2, and Δσ3 of the layers 61, 62, and 64 are
Δσ1 = (σ1max−σ1min) / 2: outermost layer 64
Δσ2 = (σ2max−σ2min) / 2: Insulating layer 62
Δσ3 = (σ3max−σ3min) / 2: conductor layer 61
It becomes. As shown in FIG. 8, the strength lines SN1, SN2, and SN3 of the layers 61, 62, and 64 are all expressed by characteristics that the lifetime (number of times) of each layer decreases as the stress amplitude Δσ increases. The bearing lines SN1, SN2, and SN3 are larger than the market input number Na converted to the maximum stroke, regardless of the magnitude of the stress amplitude Δσ.
As a result, the damage levels D1, D2, and D3 of the respective layers 61, 62, and 64 are
D1 = Na / Nf1 ≒ 0.3
D2 ＝ Na / Nf2 ≒ 0.5
D3 = Na / Nf3 ≒ 0.2
It becomes. Therefore, the strength relationship for each layer is
D1, D3 <D2 <1
Thus, all the layers of the conductor layer 61, the insulating layer 62, and the outermost layer 64 are in a range that exceeds a certain bending durability because the damage levels D1, D2, and D3 are less than 1. Of the damage levels D1, D2 and D3, the damage layer D2 is the maximum value, so that the insulating layer 62 is the weakest part.

Next, the action of determining the strength relationship for each layer in the motor cable 6 according to the first embodiment having the conductor layer 61, the insulating layer 62, the shield layer 63, and the outermost layer 64 will be described with reference to FIGS.
It should be noted that the layer of the inorganic material (metal) (conductor layer 61, shield layer 63) and the layer of organic material (resin) (insulating layer 62, outermost layer 64) vary the load of the load bearing line based on the difference in the principle of fatigue. ing. In other words, the reason for changing the vertical axis parameter of the strength line used for metal and resin is that the fatigue mechanism is because metal is dominated by load and resin is dominated by deformation, and the fatigue characteristics (life characteristics) of each material Are organized by the dominant factors.

In the conductor layer 61 and the shield layer 63 made of an inorganic material (metal), the load bearing lines SN3 and SN4 (FIG. 10) using a stress component or a total strain component as loads are used.
FIG. 9 is a nonlinear characteristic of the cable stress σ with respect to the motor position δ, and the vertical axis of FIG. 10 is the stress amplitude Δσ. Therefore, the stress amplitudes Δσ3 and Δσ4 of the layers 61 and 63 are
Δσ3 = (σ3max−σ3min) / 2: conductor layer 61
Δσ4 = (σ4max−σ4min) / 2: shield layer 63
It becomes. As shown in FIG. 10, the load bearing lines SN3 and SN4 of the layers 61 and 63 are larger than the market input number Na converted to the maximum stroke regardless of the magnitudes of the stress amplitudes Δσ3 and Δσ4.
As a result, the damage levels D3 and D4 of each layer 61 and 63 are
D3 = Na / Nf3 ≒ 0.2
D4 = Na / Nf4 ≒ 0.3
It becomes.

On the other hand, in the insulating layer 62 and the outermost layer 64 made of an organic substance (resin), the load bearing lines SN1 and SN2 (FIG. 12) having a plastic strain component as a load are used.
FIG. 11 shows the nonlinear characteristic of the plastic strain ε with respect to the motor position δ, and the vertical axis of FIG. 12 shows the plastic strain amplitude Δε. Therefore, the plastic strain amplitudes Δε1, Δε2 of the layers 64, 62 are
Δε1 = (ε1max−ε1min) / 2: outermost layer 64
Δε2 = (ε2max−ε2min) / 2: Insulating layer 62
It becomes. As shown in FIG. 12, the strength lines SN2 and SN1 of the layers 62 and 64 are larger than the market input number Na converted to the maximum stroke regardless of the magnitudes of the plastic strain amplitudes Δε1 and Δε2.
As a result, the damage levels D1, D2 of the respective layers 62, 64 are
D1 = Na / Nf1 ≒ 0.3
D2 ＝ Na / Nf2 ≒ 0.5
It becomes.

Therefore, the strength relationship of each of the conductor layer 61, the insulating layer 62, the shield layer 63, and the outermost layer 64 is as shown in FIG.
D1, D3, D4 <D2 <1
It becomes. That is, all the layers of the conductor layer 61, the insulating layer 62, the shield layer 63, and the outermost layer 64 are in a range that exceeds a certain bending durability because the damage levels D1, D2, D3, and D4 are less than 1. . Of the damage levels D1, D2, D3, and D4, the damage level D2 is the maximum value, so that the insulating layer 62 is the weakest part.

[Characteristics of motor cable]
In Example 1, in the motor cable 6 used in the in-wheel motor system, the motor cable 6 has a multilayer structure having a plurality of layers 61, 62, 63, and 64 in a coaxial arrangement. In addition, the bending durability determined by the relative movement amount and the number of times is secured to a certain value or more in all the layers 61, 62, 63, 64 that constitute the motor cable 6, and the bending durability is more than the outermost layer 64 other than the outermost layer 64. The insulating layer 62 (weakest part) having weak properties is provided.
That is, since the motor cable 6 has a multi-layer structure having a plurality of layers 61, 62, 63, 64 in a coaxial arrangement, the conductor layer 61 having a sufficient cross-sectional area to secure a necessary current can be increased in size and cost. Up is suppressed. Further, in addition to the outermost layer 64, an insulating layer 62 (weakest part) whose bending durability is weaker than that of the outermost layer 64 is provided, that is, a part where the degree of damage is maximized at the time of design is determined. Therefore, even if it is used beyond its lifetime, the insulation layer 62, which is the weakest part, can safely stop the function or detect an abnormality, ensuring the safety of the in-wheel motor system that repeats relative movement. Is done.
As a result, it is possible to ensure the safety of the in-wheel motor system that repeats relative movement while suppressing the increase in size and cost of the motor cable 6.

In Example 1, the motor cable 6 includes at least the conductor layer 61, the outermost layer 64, and the insulating layer 62 that insulates between the conductor layer 61 and the outermost layer 64 as the plurality of layers, and the insulating layer 62 is the outermost layer. It was set as the structure made into a weak part.
That is, the reason for making the insulating layer 62 the weakest part is that even if the insulating layer 62 is damaged, there is no attack to other layers, and when the insulating layer 62 is damaged, it is easy to detect due to current abnormality or the like. .
Therefore, by using the insulating layer 62 as the weakest part in durability, exposure of the conductive wire from the conductor layer 61 is prevented, and safety is increased.

In the first embodiment, a shield layer 63 is provided between the insulating layer 62 and the outermost layer 64 of the motor cable 6, and a potential difference sensor 8 is provided as a leakage detection means between the conductor layer 61 and the shield layer 63. did.
That is, there is no leakage between the conductor layer 61 and the shield layer 63 when the insulating layer 62 is not damaged and exhibits an insulating function. However, if the insulating layer 62 loses its insulating function due to damage or the like, a leakage between the conductor layer 61 and the shield layer 63 is detected before the conductive wire is exposed.
Therefore, by detecting leakage from the insulating layer 62 with an easy configuration, the effect of increasing safety by measures such as warning based on leakage detection or interruption of energization can be reliably obtained.

In the first embodiment, among the layers 61, 62, 63, and 64 constituting the motor cable 6, the layers 62 and 64 made of organic matter (resin) use the load bearing lines SN1 and SN2 that use a plastic strain component as a load. In the layers 61 and 63 made of inorganic materials (metals), the load bearing lines SN3 and SN4 having a stress component or a total strain component as loads are used. And it was set as the structure which determines the weakest part by contrast of the damage degree of each layer 61,62,63,64.
In other words, the prediction accuracy of the organic substance (resin) is higher when the damage degree is predicted by a load bearing line with a plastic strain component as a load. On the other hand, the prediction accuracy of an inorganic substance (metal) is higher when the damage level is predicted using a load bearing line with a stress component as a load.
Therefore, by optimizing the strength line used for comparing the damage level due to the difference in the material of each layer 61, 62, 63, 64, the magnitude relationship of the damage level of each layer 61, 62, 63, 64 can be accurately determined. Highest accuracy determines the weakest part in durability.

In the first embodiment, among the layers 61, 62, 63, and 64 constituting the motor cable 6, the insulation layer 62 uses the load bearing line SN2 that sets the damage level by detecting leakage. For the other layers 61, 63, and 64, the load bearing lines SN 1, SN 3, and SN 4 that set the degree of damage by exposing the conductors that form the conductor layer 61 are used. And it was set as the structure which determines the weakest part by contrast of the damage degree of each layer 61,62,63,64.
That is, with respect to the insulating layer 62, the damage level is set using the load bearing line SN2 having high safety. On the other hand, with respect to the other layers 61, 63, 64, the degree of damage is set by using the bearing lines SN1, SN3, SN4 having low safety.
Therefore, by setting the damage level setting of the insulating layer 62 to be safer than the damage level settings of the other layers 61, 63, 64, the damage levels of the layers 61, 62, 63, 64 for the purpose of ensuring safety can be reduced. The weakest part is accurately determined by the magnitude relationship.

In the first embodiment, the high-power cable is configured as a motor cable 6 in which one end is connected to the inverter 5 and the other end is connected to the in-wheel motor 4 in the in-wheel motor system.
That is, in the case of an in-wheel motor system, by connecting the other end of the motor cable 6 to the in-wheel motor 4 that follows the suspension operation, the motor cable 6 is repeatedly moved and deformed, and high bending durability is required. The Further, the motor cable 6 is required to have high safety by being exposed to the wheel house space.
Therefore, application to the in-wheel motor system can meet the high bending durability and high safety required for the motor cable 6.

Next, the effect will be described.
In the cable structure of the first embodiment, the effects listed below can be obtained.

(1) Used in a system in which the drive unit (in-wheel motor 4) repeats relative movement with respect to the power supply unit (inverter 5), and electrically between the power supply unit (inverter 5) and the drive unit (in-wheel motor 4). In the high power cable (motor cable 6) to be connected,
The high voltage cable (motor cable 6) has a multilayer structure having a plurality of layers 61, 62, 63, 64 in a coaxial arrangement,
In all layers 61, 62, 63, and 64 constituting the high-voltage cable (motor cable 6), the bending durability determined by the relative movement amount and the number of times is ensured to be a certain value or more (the damage degree D is not more than a certain value), and the maximum In addition to the outer layer 64, a weakest portion (a portion where the damage degree D is maximized) having a bending durability weaker than that of the outermost layer 64 is provided (FIG. 3).
For this reason, it is possible to ensure the safety of a system (in-wheel motor system) that repeats relative movement while suppressing the increase in size and cost of the high-power cable (motor cable 6).

(2) The high-power cable (motor cable 6) has at least a conductor layer 61, an outermost layer 64, and an insulating layer 62 that insulates between the conductor layer 61 and the outermost layer 64 as a plurality of layers. The layer 62 was taken as the weakest part (FIGS. 6-8).
For this reason, in addition to the effect of (1), since the weakest part is the insulating layer 62, exposure of the conductive wire from the conductor layer 61 is prevented, and safety can be increased.

(3) In the high-voltage cable (motor cable 6), a shield layer 63 is provided between the insulating layer 62 and the outermost layer 64, and a leakage detection means (potential difference sensor 8) is provided between the conductor layer 61 and the shield layer 63. Provided (FIGS. 3 and 4).
For this reason, in addition to the effect of (2), by detecting leakage from the insulating layer 62 with an easy configuration, it is possible to reliably obtain an effect of increasing safety by measures such as warning based on leakage detection and interruption of energization. it can.

(4) Of the layers 61, 62, 63, 64 constituting the high-power cable (motor cable 6), the layers 62, 64 made of organic matter (resin) use the load bearing lines SN1, SN2 with the plastic strain component as a load, In the layers 61 and 63 made of inorganic materials (metals), the weakest part is determined by comparing the damage levels of the layers 61, 62, 63, and 64 using the load bearing lines SN3 and SN4 loaded with stress components or total strain components ( 9-13).
For this reason, in addition to the effects of (1) to (3), by optimizing the load of the load bearing line based on the difference in the material of each layer 61, 62, 63, 64, that is, the difference in the fatigue principle, The strength relationship between the layers 61, 62, 63, 64 is accurately determined, and the weakest portion can be determined with high accuracy.

(5) Among the layers 61, 62, 63, 64 constituting the high-power cable (motor cable 6), the insulation layer 62 uses the load bearing line SN2 for setting the damage level by detecting the leakage, and the other layers 61, 63, As for 64, the weakest part is determined by comparing the degree of damage of each layer 61, 62, 63, 64 using the strength lines SN1, SN3, SN4 that set the degree of damage by exposing the conductor constituting the conductor layer 61 (FIG. 10, 12).
Therefore, in addition to the effect of (4), the setting of the damage level of the insulating layer 62 is set to be safer than the setting of the damage levels of the other layers 61, 63, 64. The weakest portion can be accurately determined by the strength relationship of 61, 62, 63, 64.

(6) The power supply unit is an inverter 5 mounted on the suspension member 1,
The drive unit is an in-wheel motor 4 in which at least a part is disposed in the wheel interior space of the drive wheels (left and right rear wheels),
The high power cable is a motor cable 6 having one end connected to the inverter 5 and the other end connected to the in-wheel motor 4 (FIGS. 1 and 2).
For this reason, in addition to the effects (1) to (5), application to an in-wheel motor system can meet the high bending durability and high safety required for the motor cable 6.

  As described above, the cable structure of the present invention has been described based on the first embodiment. However, the specific configuration is not limited to the first embodiment, and the gist of the invention according to each claim of the claims is described. Unless it deviates, design changes and additions are allowed.

  In the first embodiment, an example of a four-layer motor cable 6 having a conductor layer 61, an insulating layer 62, a shield layer 63, and an outermost layer 64 is shown as a high-power cable. However, the high-power cable may be an example of a three-layer high-power cable having a conductor layer, an insulating layer, and an outermost layer, or an example of a high-power cable having five or more layers including a separator layer, a reinforcing netting layer, and the like. It may be.

  In Example 1, the example of the motor cable 6 which made the insulating layer 62 the weakest part among several layers was shown as a strong electric cable. However, the high power cable may be an example in which a layer other than the insulating layer is the weakest part.

  In the first embodiment, the example in which the potential difference sensor 8 serving as the leakage detection means is provided between the conductor layer 61 and the shield layer 63 of the high-voltage cable has been described. However, an example in which a leakage detection circuit is provided inside the inverter may be used, and further, an example in which leakage detection means is not provided may be used.

  In Example 1, as an example of determining the damage level of each layer, an example in which plastic strain is applied as a load or a stress component is applied as a load is shown depending on the layer material. However, the means for determining the damage level of each layer may be an example in which a load other than the plastic strain or stress component is applied, or may be an example that is not divided according to the layer material.

  In the first embodiment, an example in which the cable structure of the present invention is applied to a motor cable of an in-wheel motor system has been shown. However, the cable structure of the present invention can also be applied to a high-power cable that uses a battery as a power supply unit, an in-wheel motor incorporating an inverter as a drive unit, and connects the power supply unit and the drive unit. In short, any high-power cable can be used as long as it is used in a system in which the drive unit repeats relative movement with respect to the power supply unit and electrically connects the power supply unit and the drive unit.

1 Suspension members 2L, 2R Left and right rear wheel tires 3L, 3R Left and right rear wheel 4 In-wheel motor (drive unit)
4L, 4R Left and right in-wheel motor 5 Inverter (power supply)
6 Motor cable (high power cable)
61 Conductor layer 62 Insulating layer 63 Shield layer 64 Outermost layers 6L, 6R Left and right three-phase motor cables 7L, 7R Left and right suspension devices 8 Potential difference sensor (leakage detection means)

Claims (6)

Used in a system in which the drive unit repeats relative movement with respect to the power supply unit, and in the high voltage cable that electrically connects the power supply unit and the drive unit,
The high-voltage cable has a multilayer structure having a plurality of layers in a coaxial arrangement,
The bending durability determined by the relative movement amount and the number of times in all layers constituting the high-voltage cable is ensured to be a certain value or more, and the weakest portion having a bending durability weaker than the outermost layer is provided in addition to the outermost layer. Characteristic cable structure. The cable structure according to claim 1,
The high-power cable has, as a plurality of layers, at least a conductor layer, an outermost layer, and an insulating layer that insulates between the conductor layer and the outermost layer, and the insulating layer is the weakest part. Cable structure characterized by The cable structure according to claim 2,
The high-voltage cable is characterized in that a shield layer is provided between the insulating layer and the outermost layer, and a leakage detection means is provided between the conductor layer and the shield layer. In the cable structure according to any one of claims 1 to 3,
Among the layers constituting the high-voltage cable, the layer made of organic material uses a load-bearing line loaded with a plastic strain component, and the layer made of inorganic material uses a load-bearing wire loaded with a stress component or a total strain component to damage each layer. The weakest part is determined by contrast of the degree. The cable structure according to claim 4, wherein
Of each layer constituting the high-power cable, the insulation layer uses a load-bearing line that sets the degree of damage by detecting leakage, and the other layers use the load-bearing line that sets the degree of damage by exposing the conductor constituting the conductor layer. And determining the weakest part by comparing the damage level of each layer. In the cable structure described in any one of Claim 1 to Claim 5,
The power source is an inverter mounted on a suspension member,
The drive unit is an in-wheel motor in which at least a part is disposed in a wheel inner space of a drive wheel,
The high-voltage cable is a motor cable having one end connected to the inverter and the other end connected to the in-wheel motor.