JP7508246B2 - Composite Cable - Google Patents

Description

The present invention relates to a composite cable, and in particular to a composite cable to be installed in a vehicle, etc.

2. Description of the Related Art Conventionally, an ABS cable (signal line) is known for transmitting a signal from an ABS sensor disposed near a wheel to an ABS control device in order to activate an anti-lock brake system (hereinafter referred to as ABS) in a vehicle.
Furthermore, with the recent widespread use of electric parking brakes (hereinafter referred to as EPBs), an EPB cable (power line) that supplies power from an EPB control device to an actuator of the EPB has also become known.

In a vehicle, the ABS control device and the EPB control device are positioned close to each other or in approximately the same location, while the ABS sensor and the electric brake actuator are each positioned at the wheels, so the ABS cable and the EPB cable connecting them are usually installed along similar routes within the vehicle.
For this reason, conventionally, these cables have often been installed inside a vehicle by wrapping them together in tape or bundling them with cable ties.

Meanwhile, in recent years, there has been progress in the development of composite cables that combine these cables into a single cable. For example, Patent Document 1 discloses a composite cable in which a pair of power lines (EPB cables) and a pair of signal lines (ABS cables) are sheathed together.
Furthermore, for example, Patent Documents 2 and 3 disclose composite cables having a pair of power lines and two pairs of signal lines.

In this way, combining the power line (e.g., EPB cable) and the signal line (e.g., ABS cable) into a single composite cable has the advantage that it is possible to reduce the space that the cables occupy inside the vehicle (space saving) compared to assembling the EPB cable and ABS cable separately inside the vehicle or bundling them together, as described above.

Patent No. 5541331 Patent No. 6219263 Patent No. 6424950

Incidentally, when a composite cable including a power line for the EPB and a signal line for the ABS as described above is arranged inside a vehicle, one end of the composite cable is attached to the tire (brake) part of the vehicle, so that every time the steering wheel is turned and the direction of the tire changes, the composite cable bends and stretches, and a bending force is repeatedly applied to the composite cable.
For this reason, composite cables are required to have high resistance to repeated bending (hereinafter referred to as repeated bending property, or bending resistance, etc.; in other words, the property of making it difficult for breaks, etc. to occur in the power lines and signal lines even if the composite cable is repeatedly bent).

In addition, in North America, Russia, Northern Europe, and high altitude regions, temperatures can drop to as low as -40°C, and composite cables are required to be able to withstand repeated bending forces in such extreme cold, which can cause breaks in the power and signal lines, i.e., they are required to have high repeated bending properties at low temperatures.

The present invention was made in consideration of the above problems, and aims to provide a composite cable that has excellent repeated bending properties not only at room temperature but also at low temperatures.

In order to solve the above problem, the invention described in claim 1 comprises:
In a composite cable including a plurality of signal lines and a plurality of power lines, each of which has a resin layer around the conductor,
The signal line is thinner than the power line,
The wires constituting the conductor of the signal line are twisted together,
The wires constituting the conductor of the power line are twisted together,
Two or more of the plurality of signal lines are further twisted together,
the signal line and the power line are further twisted together,
The power line is characterized in that the occupancy rate of the conductor gaps in a cross section of the power line is 26 to 40%.

Furthermore, the invention described in claim 1 is
The power line is characterized in that the cross-sectional area of the conductor is 0.5 to 4.0 mm ² , the diameter of the strands constituting the conductor is 0.05 to 0.5 mm, and the tensile strength of the strands is 350 to 900 MPa.

The invention described in claim 2 is the composite cable described in claim 1 , characterized in that the twist ratio of the strands constituting the conductor of the power line is 1.03 to 1.07.

The invention described in claim 3 is characterized in that, in the composite cable described in either claim 1 or claim 2 , the tensile modulus of elasticity of the resin layer of the power wire is 150 to 1000 MPa at (23±2)°C.

The invention described in claim 4 is characterized in that in the composite cable described in any one of claims 1 to 3 , the plurality of power supply lines includes a power supply line for vehicle brake control.

The invention described in claim 5 is a composite cable described in any one of claims 1 to 4 , characterized in that the multiple power supply lines include a power supply line that supplies power from a control device of an electric parking brake to an actuator, and the multiple signal lines include a signal line for transmitting a signal from a sensor of an anti-lock brake system to the control device.

According to the present invention, a composite cable having multiple power lines and multiple signal lines has excellent repeated bending properties not only at room temperature but also at low temperatures.

1 is a diagram showing a state in which the signal line of the composite cable is connected to an ABS sensor and an ABS control device, and the power line is connected to an EPB control device and an actuator. 1 is a cross-sectional view showing an example of the configuration of a composite cable according to an embodiment of the present invention, showing a four-core cable. 1 is a cross-sectional view showing an example of the configuration of a composite cable according to an embodiment of the present invention, showing a six-core cable. 1 is a diagram showing that the conductors of the power supply line and the signal line are formed by twisting together a plurality of wires. 1A and 1B are diagrams showing the state in which signal lines and power lines are twisted together as a whole within a composite cable, where (a) shows the case of a four-core cable and (b) shows the case of a six-core cable. 11 is a diagram illustrating an internal portion of a resin layer of a power line from which the conductor has been removed. FIG. FIG. 2 is a schematic diagram of an apparatus used in bending tests 1 to 3, viewed from the axial direction of a mandrel.

Hereinafter, a composite cable according to the present invention will be described with reference to the drawings.
However, the embodiments described below are subject to various limitations that are technically preferable for implementing the present invention, but the scope of the present invention is not limited to the following embodiments or illustrated examples.

In the following, a case will be described in which the multiple power lines in the composite cable include a power line for vehicle brake control, but the present invention is not necessarily limited to this case.
Specifically, in this embodiment, as shown in FIG. 1 , the multiple signal lines 2 of the composite cable 1 include a signal line for transmitting a signal from a sensor 11 of the anti-lock brake system to a control device 12, and the multiple power supply lines 3 include a power supply line for supplying power from a control device 13 of the electric parking brake to an actuator 14, but this is not limited to this case.

2 and 3 are cross-sectional views showing examples of the configuration of a composite cable according to this embodiment, in which FIG. 2 shows a four-core cable and FIG. 3 shows a six-core cable.
In this embodiment, the composite cable 1 includes a plurality of signal wires 2 and a plurality of power wires 3, and each of the signal wires 2 and the power wires 3 has an insulating resin layer 22, 32 on the outer periphery of a conductor 21, 31. The signal wires 2 and the power wires 3 are collectively covered with a sheath layer 4.

The sheath layer 4 may be composed of a plurality of layers.
In addition, the composite cable 1 only needs to include a plurality of signal lines 2 and a plurality of power lines 3, and is not limited to the four-core or six-core cable shown in Figures 2 and 3. Furthermore, although Figures 2 and 3 show the case where two power lines 3 are provided, three or more power lines may be provided.

Also, the dashed circles including pairs of signal wires 2 in FIG. 2 and FIG. 3 indicate that a predetermined number of signal wires 2 are twisted together.
In this manner, by configuring two or more of the multiple signal lines 2 to be twisted together, the twisted signal lines 2 become more flexible than when the signal lines 2 are not twisted together.

At the same time, when the composite cable 1 is pulled in the longitudinal direction, the twisted signal wires 2 can stretch in that direction, so that when the composite cable 1 is subjected to repeated bending forces, the twisted signal wires 2 stretch, making it less likely that breakage or the like will occur.
In this manner, by configuring two or more signal wires 2 to be twisted together, it is possible to improve the flexibility and repeated bending resistance of the composite cable 1 .

In this embodiment, the signal line 2 is thinner than the power line 3, similarly to a normal composite cable. The signal line 2 may be formed by using a metal wire such as a copper alloy or an aluminum alloy as a conductor 21, which is covered with an insulating resin layer 22 made of a resin such as polyester.
In the following description, it is assumed that the conductor 21 of the signal line 2 is a metal wire. However, the conductor 21 of the signal line 2 may include, for example, an optical fiber core.

In this embodiment, as shown in FIG. 4, the signal line 2 has a conductor 21 formed by twisting together a plurality of metal wires 21a.
Note that FIG. 4 does not indicate that the conductor 21 (strand 21a) of the signal line 2 and the conductor 31 (strand 31a) of the power line 3 described below have the same thickness.

With this configuration, the signal line 2 itself becomes more flexible than when the strands 21a of the signal line 2 are not twisted together.
At the same time, when the composite cable 1 is pulled in the longitudinal direction, the signal line 2 itself can stretch in that direction, so that when the composite cable 1 is subjected to repeated bending forces, the signal line 2 itself stretches, making it less likely to break or the like.
In this manner, by forming the conductor 21 of the signal line 2 by twisting together a plurality of strands 21a, it is possible to improve the flexibility and repeated bending resistance of the composite cable 1.

The power line 3 has an insulating resin layer 32 on the outer periphery of a conductor 31. The material constituting the conductor 31 is not particularly limited, and for example, copper, aluminum, or alloys thereof can be used, but a copper alloy wire is preferable, and among them, a copper alloy wire containing 0.1 to 1.0% Sn is particularly preferable.
Moreover, by setting the tensile strength of the copper alloy wire 31a to 350 to 900 MPa, it is possible to obtain high repetitive bending resistance.

In this case, the conductor 31 of the power line 3 preferably has a cross-sectional area of 0.5 to 4.0 ^mm2 , and more preferably 1.0 to 3.5 ^mm2 . The diameter of the strands 31a constituting the conductor 31 is preferably 0.05 to 0.5 mm, and more preferably 0.05 to 0.3 mm.
The cross-sectional shape of the wire 31a may be circular (round wire) or rectangular (rectangular wire).

4, in the power line 3, a plurality of strands 31a are twisted together to form the conductor 31. There is no restriction on the number of strands 31a as long as they are two or more.
Therefore, similarly to the case of the signal line 2 described above, the power line 3 itself becomes flexible, and when repeated bending forces are applied to the composite cable 1, the power line 3 itself stretches and is less likely to break, etc. Therefore, by configuring the conductor 31 of the power line 3 by twisting together a plurality of wires 31a, it is possible to improve the flexibility and repeated bending resistance of the composite cable 1.

If the twist pitch (the length from one arrangement of the twisted wires to the next same arrangement) of the strands 21a, 31a constituting the conductors 21, 31 of the signal line 2 and the power line 3 becomes too narrow, the twisted wires (the signal line 2 and the power line 3) become hard and lose flexibility, making them difficult to bend and reducing the ability to bend repeatedly. Also, problems such as the diameter of the conductors 21, 31 becoming thicker may occur.
Furthermore, if the twist pitch of the wires 21a, 31a becomes too wide, the signal line 2 and the power line 3 will be in a state close to being untwisted, and the effect of improving flexibility and repeated bending resistance by twisting the wires 21a, 31a will not be obtained.

Therefore, it is desirable that the twisting rates of the wires 21a and 31a are each set to an appropriate value.
In this case, the twisting ratio is defined as the ratio of the length of the extracted wires 21a, 31a to the length of the cut composite cable 1, measuring the length of the cut composite cable 1 and the length of the extracted wires 21a, 31a by dismantling the cut composite cable 1.

According to research by the present inventors, it is found that the twist ratio of the strands 21a, 31a constituting the conductors 21, 31 of the signal line 2 and the power line 3 is preferably 1.03 to 1.07, and more preferably 1.04 to 1.06.
In addition, "the twisting ratio of the wires 21a, 31a is 1.03 to 1.07" means that the length of the wires 21a, 31a of the signal wire 2 and the power wire 3 extracted by dismantling the cut composite cable 1 is 3 to 7% longer than the length of the cut composite cable 1.

With this configuration, it is possible to improve the flexibility and repeated bending resistance of the composite cable 1 without the signal line 2 or the power line 3 becoming unnecessarily high in electrical resistance or unnecessarily decreasing in signal.
The twisting ratio of the wire 31a can be adjusted by the twist pitch of the conductor 31, the twist pitch of the signal wire 2 and the power wire 3 described below, and the outer diameter of each wire (wires 21a, 31a, signal wire 2, power wire 3), etc.

In this embodiment, as shown in FIG. 5( a ), inside the composite cable 1 , the twisted signal wires 2 and the power wires 3 are further twisted together overall.
As a result, the overall flexibility of the twisted signal wires 2 and power wires 3 is improved, and when repeated bending forces are applied to the composite cable 1, the signal wires 2 and power wires 3 stretch overall, making it less likely that breaks will occur in the signal wires 2 and power wires 3.

Therefore, by further twisting the signal wires 2 and the power wires 3 together as a whole, it is possible to improve the overall flexibility and repeated bending resistance of the composite cable 1.
Although FIG. 5A shows a case where the composite cable 1 has four cores (see FIG. 2), the same applies to other configurations. For example, in the case of the six cores shown in FIG. 3, it would look like FIG. 5B.

As described above, in the composite cable 1 according to this embodiment, the signal line 2 itself and the power line 3 itself are constructed by twisting the strands 21a, 31a (see FIG. 4), the signal lines 2 are twisted together (see FIG. 2 and FIG. 5(a), (b)), and the signal line 2 and the power line 3 are twisted together as a whole (see FIG. 5(a), (b)). The twisted structure of the signal line 2 and the power line 3 improves the repeated bending resistance of the composite cable 1.

On the other hand, when comparing the signal line 2 and the power line 3, the effect on the repeated bending resistance of the composite cable 1 is greater for the thicker power line 3 than for the signal line 2.
In the present invention, the wires 31a of the power line 3 are twisted together as described above, so that the power line 3 itself is configured to have the ability to be repeatedly bent.

However, for example, if the conductor 31 (strands 31a) are densely packed in the resin layer 32, the power line 3 becomes hard and difficult to bend, and the repeated bending resistance of the power line 3 itself may be reduced.
The degree of packing of the wires 31a in the power line 3 can be expressed as the void occupancy rate α of the conductor 31 in the cross section of the power line 3, and the void occupancy rate α can be calculated by the following method.

That is, a microscope capable of measuring the area of a region is used to determine the cross-sectional area of the internal portion A (see the dotted portion in FIG. 6) of the resin layer 32 of the power line 3 from which the conductor 31 has been removed. Note that the dotted region in FIG. 6 represents the internal portion A of the power line 3, and does not represent the presence of any object such as a conductor therein.
Then, the cross-sectional area of the conductor 31 is calculated based on the configuration of the conductor 31 (the cross-sectional area of each of the wires 31a and the number of wires 31a).
α = (cross-sectional area of inner part - cross-sectional area of conductor) / (cross-sectional area of inner part) x 100 [%]
By calculating the above, the occupancy rate α of the gap of the conductor 31 in the cross section of the power line 3 can be calculated.

If the void occupancy rate α is too small (i.e., if the conductor 31 is densely packed in the resin layer 32), the power line 3 becomes hard, and there is a possibility that the repeated bending resistance of the power line 3 itself will be reduced.
Conversely, if the void occupancy rate α is too large, i.e., if the conductor 31 is loosely packed in the resin layer 32, the power line 3 itself may be more resistant to repeated bending. However, as the composite cable 1 is bent, the shape change due to the radial stress applied to the resin layer 32 of the power line 3 becomes excessive, and the resin layer 32 of the power line 3 may be damaged.

Therefore, the inventors' research has revealed that it is preferable that the void occupancy rate α of the conductor 31 in the cross section of the power line 3 is 26 to 40%.
Furthermore, if the resin layer 32 of the power line 3 is too hard, the repeated bending resistance of the power line 3 itself will decrease, but if it is too soft, problems such as damage to the resin layer 32 will occur when the power line 3 is repeatedly bent as described above. Therefore, it is preferable that the resin layer 32 of the power line 3 has a tensile modulus of elasticity of 150 to 1000 MPa. The tensile modulus of elasticity can be determined according to JIS K 7161-1. When measuring the tensile modulus of elasticity of the coating (resin layer 32) of the power line, a tubular test piece of the coating is taken from the power line and measured according to JIS C 3005 (tensile strength of insulators and sheaths). The length of the test piece is about 150 mm, and marked lines are drawn at intervals of 50 mm in the center of the test piece.

As described above, in the composite cable 1 according to this embodiment, the wires 21a, 31a constituting the conductors 21, 31 of the signal line 2 and the power line 3 are twisted together, two or more signal lines 2 are twisted together, and further the signal line 2 and the power line 3 are twisted together as a whole.
At the same time, the occupancy rate α of the voids in the conductor 31 in the cross section of the power line 3 is set to 26 to 40%.

Therefore, the twisted structure of the signal wires 2 and the power wires 3 makes it possible to improve the repeated bending resistance of the composite cable 1, and by keeping the void occupancy rate α within the above range, the repeated bending resistance of the power wires 3 themselves is improved, and the repeated bending resistance of the composite cable 1 can be further improved.
As will be shown in the examples described later, the composite cable 1 according to this embodiment has excellent repeated bending properties not only at room temperature but also at low temperatures.

Here, we will explain the tests that were conducted on the composite cable 1 according to this embodiment (Examples 1 to 4) and composite cables with other configurations (Comparative Examples 1 to 5) regarding repeated bending properties, etc.

[Creating a signal line]
A conductor was prepared by twisting together strands of copper alloy wire containing 0.3% Sn and having a diameter of 0.08 mm. This conductor was then extruded with polyethylene (Sumikathene CU5003, manufactured by Sumitomo Chemical) to give an outer wire diameter of 1.4 mm and a resin layer thickness of 0.35 mm. After that, a cross-linking process was performed in which the resin layer was cross-linked by irradiating it with an electron beam of 750 keV and 8 Mrad to obtain a signal wire.

[Creating power lines]
A conductor was prepared by twisting together strands of 0.08 mm diameter copper alloy wire containing 0.15% Sn, and this was then extruded with polyethylene (Sumikathene CU5003 (manufactured by Sumitomo Chemical)) to give an outer wire diameter of 2.6 mm and a resin layer thickness of 0.45 mm. After that, a crosslinking process was performed in which the resin layer was crosslinked by irradiating it with an electron beam of 500 keV and 8 Mrad to obtain a power line.

[Cable core]
Two of the obtained signal wires were twisted together, and the twisted signal wire and two power wires were further twisted together to prepare a cable core.

[Creating a composite cable]
The obtained cable core was made of a material consisting of flame-retardant cross-linked polyurethane, which is a polyurethane-based resin, and extrusion molding was performed so that the cable outer diameter was 8.3 mm to form a sheath layer around the cable core. After that, as a cross-linking process, the sheath layer was cross-linked by irradiating it with an electron beam of 800 keV and 12 Mrad to obtain a composite cable.

Moreover, the composite cable produced as described above was subjected to the following three types of bending tests.
FIG. 7 is a schematic diagram of the device used in the following bending tests 1 to 3, as viewed from the axial direction of the mandrel.

<Bending test 1>
As shown in FIG. 7 , the manufactured cable 100 was passed vertically between two mandrels 51, 52 arranged horizontally and parallel to each other, and between anti-sway retainers 61, 62, and a weight (not shown) was attached below the composite cable 100.
In this state, the upper end of the composite cable 100 was bent (alternately repeated left and right) so as to alternately contact the upper outer periphery of the left and right mandrels 51 or 52. The number of bending times was counted as one bending when the composite cable 100 was bent so as to contact the outer periphery of either the left or right mandrel 51, 52.

The test conditions were a mandrel diameter of 15 mm, a left-right bending angle of 90°, and a speed of 60 bends/min. The weight was 500 g, the clearance between the composite cable and the mandrel was 1 mm, and the length of the bend was adjusted so that the upper side of the composite cable 100 was in contact with the upper outer circumference of each mandrel. The test was performed in an atmosphere of 25°C. The composite cables were connected in series in a loop shape and electricity was passed through them, and the number of bends until a break occurred was measured.

The evaluation was performed based on whether the number of times the power line or signal line was bent before the first break occurred fell within any of the following criteria: "◯" and "Δ" are acceptable, and "×" is unacceptable.
○: 100,000 times or more △: 50,000 times or more, less than 100,000 times ×: Less than 50,000 times

<Flex test 2>
The bending test 2 was a severe test similar to the bending test 1 described above, except that the mandrel diameter was 8 mm.
The evaluation was performed based on whether the number of times the power line or signal line was bent before the first break occurred fell within any of the following criteria: "◯" and "Δ" are acceptable, and "×" is unacceptable.
○: 100,000 times or more △: 50,000 times or more, less than 100,000 times ×: Less than 50,000 times

<Bending test 3>
A bending test was conducted at cryogenic temperatures.
The test contents were the same as those of the bending tests 1 and 2, but the test was carried out in an atmosphere of -40°C.
The evaluation was performed based on whether the number of times the power line or signal line was bent before the first break occurred fell within any of the following criteria: "◯" and "Δ" are acceptable, and "×" is unacceptable.
○: 100,000 times or more △: 50,000 times or more, less than 100,000 times ×: Less than 50,000 times

The results of performance evaluation of the bending resistance of the various composite cables prepared are shown in Table I below.
In Table I, the results of the above bending tests 1 to 3 are shown as bending resistance 1 to 3, respectively. In Table I, the presence or absence of twisting of the power lines, etc. is shown as "yes" or "no", but because it is difficult to completely avoid twisting due to manufacturing constraints on the power lines, etc., the cases where no twisting is performed (the cases of "no" in Table I) include cases where the twisting is sufficiently small.

In Examples 1 to 4, good results were obtained for all of bending resistance 1 to 3. In other words, good results were obtained under normal conditions, more severe bending conditions, and extremely low temperature conditions.

On the other hand, in Comparative Example 1, the void occupancy rate α of the conductor in the cross section of the power line was set to 55%, but because the void occupancy rate α was too large, the resin layer of the power line was damaged by repeated bending in all of Bending Tests 1 to 3, and as a result, the power line broke after a relatively small number of bending cycles, resulting in poor repeated bending resistance.
In addition, in Comparative Examples 2 to 5, the power supply lines, signal lines, pairs of signal lines, or the entire power supply lines and signal lines were not twisted. However, in all of these cases, at least in Bending Test 2 (stricter bending conditions) and Bending Test 3 (extremely low temperature conditions), breaks occurred in the power supply lines and signal lines after a relatively small number of bending cycles, and the repeated bending resistance was poor.

It goes without saying that the present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention.
For example, although the case where only one sheath layer 4 is formed is shown in FIG. 2 and FIG. 3, the sheath layer 4 can be formed in a plurality of layers.

In addition, since the part of the vehicle in which the composite cable 1 is arranged may become relatively hot, it is also possible to configure the sheath layer 4 of the composite cable 1 (or any one of the multiple sheath layers 4) and the resin layers 22, 32 of the signal line 2 and power line 3 to be made of a heat-resistant resin, etc.

REFERENCE SIGNS LIST 1 composite cable 2 signal line 3 power line 11 sensor 12 control device 13 control device 14 actuator 21 conductor 21a strand 22 resin layer 31 conductor 31a strand 32 resin layer α void occupancy

Claims (5)

In a composite cable including a plurality of signal lines and a plurality of power lines, each of which has a resin layer around the conductor,
The signal line is thinner than the power line,
The wires constituting the conductor of the signal line are twisted together,
The wires constituting the conductor of the power line are twisted together,
Two or more of the plurality of signal lines are further twisted together,
the signal line and the power line are further twisted together,
the occupancy rate of the conductor gap in the cross section of the power line is 26 to 40%;
The power line is a composite cable, characterized in that the cross-sectional area of the conductor is 0.5 to 4.0 mm ² , the diameter of the strands constituting the conductor is 0.05 to 0.5 mm, and the tensile strength of the strands is 350 to 900 MPa . 2. The composite cable according to claim 1 , wherein the twist ratio of the strands constituting the conductor of the power line is 1.03 to 1.07. The composite cable according to claim 1 or 2 , characterized in that the resin layer of the power line has a tensile modulus of elasticity of 150 to 1000 MPa at (23±2)°C. 4. The composite cable according to claim 1, wherein the plurality of power lines includes a power line for controlling a brake of a vehicle. 5. The composite cable according to claim 1, wherein the plurality of power supply lines includes a power supply line for supplying power from a control device of an electric parking brake to an actuator, and the plurality of signal lines includes a signal line for transmitting a signal from a sensor of an anti-lock brake system to the control device.

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