In-vehicle communication systems and communication cables

Abstract

To provide an onboard communication system capable of easily maintaining a distance between conductors of a cable mounted on a vehicle.SOLUTION: An onboard communication system 10 comprises: a transmitter 21 transmitting a differential signal; a receiver 31 for receiving the differential signal; and a communication cable 40 for connecting the transmitter 21 and the receiver 31 and transmitting the differential signal. The communication cable 40 comprises: a twisted wire 50; a sheath for covering the twisted wire 50; and a talc layer provided between the twisted wire 50 and the sheath. The sheath has a pair of ribs which is positioned so that the ribs hold therebetween, a straight line connecting a conductor center of a first cable 51 and a conductor center of a second cable 52 on a cross section of the communication cable 40. The talc layer is provided along a surface of the twisted wire 50.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to an in-vehicle communication system and a communication cable.

Background Art

[0002] Patent Document 1 discloses an interface circuit of a communication device that transmits signals between electrical equipment of a vehicle. In the communication device of Patent Document 1, the signal transmission line of the interface circuit is composed of a pair of differential transmission lines.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, a pair of differential transmission lines of the interface circuit are connected to a cable via a connector. In the cable, it is desired to maintain the distance between conductors.

[0005] Therefore, an object is to make it easy to maintain the distance between conductors of a cable mounted in a vehicle.

Means for Solving the Problems

[0006] The in-vehicle communication system of the present disclosure comprises a transmitter that transmits a differential signal, a receiver that receives the differential signal, and a communication cable connecting the transmitter and the receiver and transmitting the differential signal, wherein the communication cable includes a twisted wire formed by twisting together a first insulated wire and a second insulated wire, a sheath covering the twisted wire, and a talc layer provided between the twisted wire and the sheath, wherein the sheath has a cylindrical portion surrounding the first insulated wire and the second insulated wire, and each portion extending from the cylindrical portion to the first insulated wire The communication cable has a pair of ribs that protrude inward from the communication cable and extend spirally in the direction of extension of the communication cable, and in a cross-section of the communication cable, the pair of ribs are positioned on either side of a straight line connecting the conductor center of the first insulated wire and the conductor center of the second insulated wire so as to divide a first space where the first insulated wire is arranged and a second space where the second insulated wire is arranged, and the talc layer is provided along the surface of the twisted wire, in this in-vehicle communication system. [Effects of the Invention]

[0007] According to this disclosure, it becomes easier to maintain the distance between conductors of cables installed in a vehicle. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram showing an in-vehicle communication system according to Embodiment 1. [Figure 2] Figure 2 is a schematic block diagram showing an in-vehicle communication system according to Embodiment 1. [Figure 3] Figure 3 is a plan view showing a communication cable. [Figure 4] Figure 4 is a cross-sectional view along the line IV-IV in Figure 3. [Figure 5] Figure 5 shows an example of a bent section in a communication cable. [Figure 6] Figure 6 shows the end of a communication cable. [Figure 7] Figure 7 shows the evaluation results of the communication cable. [Figure 8]Figure 8 shows the evaluation results of the communication cable. [Figure 9] Figure 9 is a cross-sectional view showing the communication cable of sample S8. [Figure 10] Figure 10 is a cross-sectional view showing the communication cable of sample S13. [Figure 11] Figure 11 shows the bending position of a communication cable when measuring its characteristic impedance in a bent state. [Modes for carrying out the invention]

[0009] [Description of Embodiments in this Disclosure] First, the embodiments of this disclosure will be listed and described.

[0010] The in-vehicle communication system disclosed herein is as follows:

[0011] (1) A transmitter that transmits a differential signal, a receiver that receives the differential signal, and a communication cable that connects the transmitter and the receiver and transmits the differential signal, wherein the communication cable includes a twisted wire formed by twisting together a first insulated wire and a second insulated wire, a sheath covering the twisted wire, and a talc layer provided between the twisted wire and the sheath, wherein the sheath has a cylindrical portion that surrounds the first insulated wire and the second insulated wire, and each of the cylindrical portions that separates the first insulated wire and the second insulated wire. The in-vehicle communication system has a pair of ribs that protrude inward from the communication cable and extend spirally in the direction of the communication cable's extension, and in a cross-section of the communication cable, the pair of ribs are positioned on either side of a straight line connecting the conductor center of the first insulated wire and the conductor center of the second insulated wire so as to divide a first space where the first insulated wire is arranged and a second space where the second insulated wire is arranged, and the talc layer is provided along the surface of the twisted wire. With the in-vehicle communication system configured in this way, since the talc layer is provided along the surface of the twisted wire, each rib does not obstruct the passage between the first insulated wire and the second insulated wire. As a result, the position through which the first and second insulated wires pass can be restricted by the pair of ribs, thereby reducing noise caused by fluctuations in the relative positional relationship between the wires of the twisted wire, which is a problem in communication cables. Furthermore, the talc layer facilitates the stripping of the sheath in the communication cable.

[0012] (2) In the in-vehicle communication system of (1), a portion of the communication cable along its extending direction may be a straight section, and another portion may be a curved section, and the pair of ribs may partition the first space and the second space in both the straight section and the curved section. This allows for good regulation of the positional relationship between the first insulated wire and the second insulated wire in both the straight section and the curved section.

[0013] (3) In the in-vehicle communication system of (2), the distance between the conductors of the first covered wire and the second covered wire may be constant in both the straight section and the bent section. Thereby, it is possible to reduce noise caused by fluctuations in the relative positional relationship between the wires of the twisted pair, which is a problem in communication cables.

[0014] (4) In any one of the in-vehicle communication systems of (1) to (3), the pair of ribs may be provided over the entire length of the sheath. Thereby, the positional relationship between the first covered wire and the second covered wire can be well regulated over the entire length of the sheath.

[0015] (5) In any one of the in-vehicle communication systems of (1) to (4), the tips of the pair of ribs are separated from each other, and between the pair of ribs, the first space and the second space communicate with each other, and the insulating coverings of the first covered wire and the second covered wire may be in direct contact with each other without passing through the talc layer. Thereby, the distance between the conductors of the first covered wire and the second covered wire and the diameter of the communication cable can be reduced.

[0016] (6) In any one of the in-vehicle communication systems of (1) to (5), the pitch of the helix of each of the pair of ribs may be set to be constant over the entire length of the section where the pair of ribs is provided. Thereby, it becomes easier to keep the pitch of the first covered wire and the second covered wire passing through the first space and the second space partitioned by the pair of ribs constant.

[0017] (7) In any one of the in-vehicle communication systems of (1) to (6), one end portion and the other end portion along the extending direction of the communication cable are sheath outer sections where the twisted pair extends out of the sheath, and a first connector for connecting the twisted pair and the transmitter is provided in the sheath outer section of the one end portion, and a second connector for connecting the twisted pair and the receiver may be provided in the sheath outer section of the other end portion. Thereby, the communication cable can be easily connected to each of the transmitter and the receiver.

[0018] (8) In any one of the in-vehicle communication systems (1) to (7), the sheath may cover only the twisted wire and the talc layer. Thereby, the structure of the communication cable becomes simple and the cost is reduced.

[0019] (9) In any one of the in-vehicle communication systems (1) to (8), the powdered talc in the talc layer contains magnesium hydroxide and silicate, the powdered talc is white, and the color of the sheath may be different from the color of the powdered talc. Thereby, when the sheath is peeled off, it becomes easy to identify the completion of the peeling by checking the color of the peeled part.

[0020] (10) In any one of the in-vehicle communication systems (1) to (9), the average particle diameter of the powdered talc in the talc layer may be from 1 μm to 20 μm. Thereby, in the communication cable, good peelability and good characteristic impedance are easily obtained.

[0021] (11) In any one of the in-vehicle communication systems (1) to (10), the following characteristic impedance measurement method: <Characteristic Impedance Measurement Method> Conform to the measurement method specified in IEC62153-1-1, except for the following points: The measurement posture of the measured sample is changed to a bent posture instead of the normal linear posture, The bent posture is such that the middle part of the measured sample is bent in a loop with a bending radius of 20 mm and the inside of the loop is hollow; The value of the characteristic impedance of the communication cable in the bent state measured may be 94 Ω or more and 106 Ω or less. Thereby, even when the communication cable is bent and arranged in a vehicle, good characteristic impedance is easily obtained.

[0022] (12) In any one of the in-vehicle communication systems from (1) to (11), the characteristic impedance value of the communication cable measured in accordance with IEC62153-1-1 after a fatigue test specified in ISO19642-2, using a 300g weight and a mandrel with a diameter of 15mm, may be 94Ω or more and 106Ω or less. In-vehicle communication cables are prone to repeated bending due to vibration, etc. Even in this case, if the characteristic impedance value after a fatigue test specified in ISO19642-2, using a 300g weight and a mandrel with a diameter of 15mm, is 94Ω or more and 106Ω or less, a good characteristic impedance can be easily obtained even in a communication cable after years of use.

[0023] (13) The communication cable of the present disclosure is a communication cable used in an in-vehicle communication system using differential signals, comprising: a twisted wire formed by twisting together a first insulated wire and a second insulated wire; a sheath that covers the twisted wire collectively; and a talc layer provided between the twisted wire and the sheath, wherein the sheath has a cylindrical portion surrounding the first insulated wire and the second insulated wire, and a pair of ribs that each protrude inward from the cylindrical portion into the space between the first insulated wire and the second insulated wire, extending spirally in the direction of the extension of the communication cable, wherein in a cross-section of the communication cable, the pair of ribs are positioned on either side of a straight line connecting the conductor center of the first insulated wire and the conductor center of the second insulated wire so as to divide a first space where the first insulated wire is arranged and a second space where the second insulated wire is arranged, and the talc layer is provided along the surface of the twisted wire. This makes it possible to reduce noise in in-vehicle communication systems using differential signals via the communication cable in question.

[0024] [Details of the embodiments of this disclosure] Specific examples of the in-vehicle communication system described herein will be explained below with reference to the drawings. However, this disclosure is not limited to these examples, and all modifications within the meaning and scope of the claims are intended to be included. In the following, unless otherwise specified, the latest standards available at the time of filing of this patent application, such as JIS, ISO, and IEC, are adopted.

[0025] [Embodiment 1] The following describes the in-vehicle communication system according to Embodiment 1. Figure 1 is a schematic diagram showing the in-vehicle communication system 10 according to Embodiment 1. Figure 2 is a schematic block diagram showing the in-vehicle communication system 10 according to Embodiment 1. Figure 3 is a plan view showing the communication cable 40. Figure 4 is a cross-sectional view along line IV-IV in Figure 3. Figure 5 is a diagram showing the bent section 42 of the communication cable 40. Figure 6 is a diagram showing the end of the communication cable 40.

[0026] The in-vehicle communication system 10 comprises a transmitter 21, a receiver 31, and a communication cable 40. The transmitter 21 transmits differential signals. The receiver 31 receives differential signals. The transmitter 21 and the receiver 31 are positioned at separate locations from each other in the vehicle 90. The communication cable 40 connects the transmitter 21 and the receiver 31 and transmits differential signals.

[0027] In the example shown in Figure 2, the in-vehicle communication system 10 includes a first ECU (electronic control unit) 20 and a second ECU 30. The first ECU 20 includes a transmitter 21, and the second ECU 30 includes a receiver 31. A communication cable 40 connects the first ECU 20 and the second ECU 30. Each ECU 20 and 30 may include both a transmitter 21 and a receiver 31, and the first ECU 20 and the second ECU 30 may be configured to communicate bidirectionally via the communication cable 40.

[0028] The first ECU 20 includes a transmitter 21, a parallel-to-serial converter 22, and a first ECU-side connector 23. Parallel data PTX, to be transmitted to the second ECU 30, is generated either inside or outside the first ECU 20. The content of the parallel data PTX is not particularly limited and may include, for example, image data or audio data. The parallel-to-serial converter 22 converts the parallel data PTX into serial data STX. The first ECU 20 is connected to one end of the communication cable 40 via the first ECU-side connector 23. The transmitter 21 is coupled to one end of the communication cable 40 and drives the communication cable 40 in response to the serial data STX. This transmits the serial data STX from the first ECU 20 to the second ECU 30.

[0029] The second ECU 30 includes a receiver 31, a serial-to-parallel converter 32, and a second ECU-side connector 33. The second ECU 30 is connected to the other end of the communication cable 40 via the second ECU-side connector 33. The receiver 31 is coupled to the other end of the communication cable 40 and receives serial data S transmitted from the first ECU 20. The serial-to-parallel converter 32 converts the serial data SRX received by the receiver 31 into parallel data PRX. The parallel data PRX is supplied to a circuit block (not shown).

[0030] The communication cable 40 is routed between the transmitter 21 and the receiver 31, having a straight section 41 and a bent section 42. A portion of the communication cable 40 along its extending direction is a straight section 41 that extends in a straight line, while another portion is a bent section 42 that extends in a curved manner.

[0031] The straight section 41 is a section between the transmitter 21 and the receiver 31, and is a section along a straight path. In the straight section 41, the communication cable 40 is arranged so that it extends through two points along the shortest path, thereby shortening the cable length of the communication cable 40 in the vehicle 90.

[0032] The bending section 42 is a section between the transmitter 21 and the receiver 31, and is a section along a curved path. In the bending section 42, the communication cable 40 bends, allowing it to be routed while avoiding locations where it is unsuitable for routing in the vehicle 90. Locations where it is unsuitable for routing in the vehicle 90 include, for example, locations with obstacles, locations that cross interiors, and locations that are exposed inside the interior.

[0033] The communication cable 40 comprises twisted wires 50, a sheath 60, and a talc layer 70.

[0034] The twisted wire 50 includes a first insulated wire 51 and a second insulated wire 52. The first insulated wire 51 and the second insulated wire 52 are twisted together.

[0035] The sheath 60 covers the twisted wire 50. Here, the sheath 60 covers only the twisted wire 50 and the talc layer 70. There may be other parts covered by the sheath 60 besides the twisted wire 50 and the talc layer 70. The sheath 60 is formed by extruding a softened resin material around the twisted wire 50 and the talc layer 70. The main component resin material of the sheath 60 may be, for example, polypropylene (PP), polyvinyl chloride (PVC), polyethylene (PE), etc. In addition to the main component resin material, additives such as plasticizers may be added to the sheath 60. The sheath 60 has a cylindrical portion 61 and a pair of ribs 64.

[0036] The cylindrical portion 61 surrounds the first insulated wire 51 and the second insulated wire 52. Here, in the cross-section of the communication cable 40, the outer shape of the sheath 60 is circular. Therefore, the cylindrical portion 61 has a cylindrical part 62 and an inner part 63. As shown in Figure 4, perpendicular to the longitudinal direction of the communication cable 40. Exchange The cross-section shown is the cross-section of the communication cable 40.

[0037] The cylindrical portion 62 is a portion of the sheath 60 with a constant thickness, including the outermost part. The thickness of the cylindrical portion 62 is the same as the thickness of the sheath 60 in the direction in which the straight line (imaginary line L in Figure 4) connecting the central axis of the first insulated wire 51 and the central axis of the second insulated wire 52 extends. The cylindrical portion 62 is, for example, the portion between the imaginary line C in Figure 4 and the outer surface of the sheath 60.

[0038] The inner portion 63 is the part that protrudes inward from the cylindrical portion 62. The inner portion 63 is the part between the cylindrical portion 62 and the rib 64. The inner portion 63 is, for example, the part between the imaginary line C and the imaginary line T in Figure 4. The imaginary line T is the common tangent between the talc layer 70 on the first insulated wire 51 side and the talc layer 70 on the second insulated wire 52 side in the part where the first insulated wire 51 and the second insulated wire 52 face each other.

[0039] Each pair of ribs 64 protrudes inward from the cylindrical portion 61 into the space between the first insulated wire 51 and the second insulated wire 52 within the communication cable 40. The ribs 64 protrude inward from the inner portion 63 within the communication cable 40. The ribs 64 are, for example, located inside the communication cable 40 beyond the imaginary line T in Figure 4. The tips of the ribs 64 protrude inward (towards the imaginary line L) beyond the common tangent of the first insulated wire 51 and the second insulated wire 52. The distance between the tips of the ribs 64 is smaller than the diameter of the insulated wires.

[0040] In a cross-section of the communication cable 40, the pair of ribs 64 are positioned on either side of a straight line (imaginary line L) connecting the conductor centers of the first insulated wire 51 and the conductor centers of the second insulated wire 52. The pair of ribs 64 divide the internal space of the cylindrical portion 61 into a first space 65 and a second space 66. The first space 65 is the space where the first insulated wire 51 is arranged. The second space 66 is the space where the second insulated wire 52 is arranged. The tips of the pair of ribs 64 are spaced apart. The first space 65 and the second space 66 are in communication with each other.

[0041] The pair of ribs 64 extend spirally in the direction of the communication cable 40. The pitch of each spiral in the pair of ribs 64 is set to be constant over the entire length of the section in which the pair of ribs 64 are provided. The pair of ribs 64 are provided over the entire length of the sheath 60.

[0042] The pair of ribs 64 demarcate the first space 65 and the second space 66 in both the straight section 41 and the curved section 42.

[0043] The positions of the first insulated wire 51 and the second insulated wire 52 within the sheath 60 are restricted by a pair of ribs 64. The distance between the conductors of the first insulated wire 51 and the second insulated wire 52 is constant in both the straight section 41 and the bent section 42.

[0044] The sheath 60 may be formed to have a predetermined hardness. In this embodiment, Shore A (JIS K6253-3) is used as the standard for the hardness of the sheath 60. The predetermined hardness is a hardness that satisfies Shore A 40 to 100. Preferably, the hardness of the sheath 60 is Shore A 60 to 90.

[0045] The hardness of Sheath 60 can be changed by any method. For example, the hardness of Sheath 60 can be changed by changing the degree of polymerization of the main component resin material. Alternatively, the hardness of Sheath 60 can also be changed by changing the composition of additives.

[0046] The talc layer 70 is provided between the twisted wire 50 and the sheath 60. The talc layer 70 is provided along the surface of the twisted wire 50. In the cross-section of the communication cable 40, the shape of the talc layer 70 corresponds to the shape of the surface of the twisted wire 50. Here, the talc layer 70 is in contact with both the twisted wire 50 and the sheath 60. The talc layer 70 is in contact with the outer surface of the twisted wire 50. The talc layer 70 is in contact with the inner surface of the sheath 60.

[0047] Here, the talc layer 70 is not present between the first insulated wire 51 and the second insulated wire 52. The insulating coating 54 of the first insulated wire 51 and the insulating coating 54 of the second insulated wire 52 are in direct contact between the pair of ribs 64 without the talc layer 70 in between. The talc layer 70 is provided on the surfaces of the first insulated wire 51 and the second insulated wire 52, excluding the contact portion between the first insulated wire 51 and the second insulated wire 52. The entire talc layer 70 is provided along the inner surface of the sheath 60. However, a portion of the talc layer 70 may be present between the first insulated wire 51 and the second insulated wire 52.

[0048] The talc layer 70 is formed, for example, by adhering countless powdered talc particles to the surface of the twisted wire 50. Any method can be used to adhere the powdered talc to the surface of the twisted wire 50; for example, the powdered talc may be sprayed onto the twisted wire 50, or the twisted wire 50 may be passed through a tank of powdered talc.

[0049] The powdered talc in the talc layer 70 contains magnesium hydroxide and silicate. The powdered talc is white in color. The color of the sheath 60 is different from the color of the powdered talc. The powdered talc may be the same color as the sheath 60, or various colors other than white may be used. Compared to using other lubricants, such as liquid lubricants, powdered talc can reduce the impact on the communication characteristics of the communication cable 40.

[0050] The average particle size of the powdered talc in the talc layer 70 is, for example, 1 μm or more and 20 μm or less. The average particle size of the powdered talc in the talc layer 70 may be 2 μm or more and 12 μm or less. The average particle size of the powdered talc in the talc layer 70 may be 3 μm or more and 6 μm or less. The average particle size of the powdered talc can be determined, for example, using a laser diffraction scattering particle size analyzer.

[0051] One end and the other end of the communication cable 40 along its extending direction are designated as an out-of-sheath section 43 where the twisted wire 50 extends out of the sheath 60. A first connector 80 is provided in the out-of-sheath section 43 at one end of the communication cable 40. The first connector 80 connects the twisted wire 50 to the transmitter 21. A second connector 81 is provided in the out-of-sheath section 43 at the other end of the communication cable 40. The second connector 81 connects the twisted wire 50 to the receiver 31.

[0052] The first connector 80 includes a pair of connector terminals 82 and a connector housing 83. The second connector 81 similarly includes a pair of connector terminals 82 and a connector housing 83.

[0053] Each connector terminal 82 has a wire connection portion and a mating portion. The wire connection portion of one of the pair of connector terminals 82 is connected to the end of the first insulated wire 51. The wire connection portion of the other of the pair of connector terminals 82 is connected to the end of the second insulated wire 52. The method of connection between the wire connection portion of the connector terminal 82 and the core wire 53 of the wire is not particularly limited and can be done by, for example, crimping, pressure welding, welding, etc.

[0054] The connector housing 83 is molded from an insulating resin or the like. The connector housing 83 houses a pair of connector terminals 82. The ends of the insulated wires connected to the connector terminals 82 are also housed in the connector housing 83. The connector housing 83 may be a part molded separately from the connector terminals 82 and the wire ends, without the connector terminals 82 and the wire ends being insert parts. The connector terminals 82 and the wire ends may be inserted into the cavity of the connector housing 83. The connector housing 83 may be a part that is insert-molded with the connector terminals 82 and the wire ends as insert parts.

[0055] The communication quality of the communication cable 40 is related, for example, to its characteristic impedance. The characteristic impedance of the communication cable 40 can vary depending on the state of the communication cable 40. The characteristic impedance of a typical communication cable 40 is measured when the communication cable 40 is not bent. For example, the method for measuring the characteristic impedance of a straight communication cable 40 shall conform to the measurement method specified in IEC62153-1-1.

[0056] In the communication cable 40, the method for measuring the characteristic impedance in a bent state conforms to the measurement method specified in IEC62153-1-1, except for the following points. The sample to be measured is normally straight, but the middle section is bent once with a bending radius of 20 mm. This bent state is the state in which the sample to be measured is bent on its own, not wrapped around an object. This is because wrapping the sample to be measured around an object may affect the measurement results of the characteristic impedance. In the communication cable 40, the characteristic impedance in a bent state measured by the above measurement method is preferably 90 Ω or more and 110 Ω or less, more preferably 94 Ω or more and 106 Ω or less, and more preferably 97 Ω or more and 103 Ω or less.

[0057] In the communication cable 40, the characteristic impedance value after a fatigue test specified in ISO19642-2, using a weight of 300g and a mandrel diameter of 15mm, is preferably 90Ω to 110Ω, more preferably 94Ω to 106Ω, and more preferably 97Ω to 103Ω.

[0058] <Effects, etc.> With the in-vehicle communication system 10 and communication cable 40 configured in this way, the talc layer 70 is provided along the surface of the twisted wire 50, so that each rib 64 does not obstruct the space between the first insulated wire 51 and the second insulated wire 52. As a result, the positions through which the first insulated wire 51 and the second insulated wire 52 pass are regulated by the pair of ribs 64, thereby reducing noise caused by fluctuations in the relative positional relationship between the wires of the twisted wire 50, which is a problem in the communication cable 40. Furthermore, the talc layer 70 facilitates the stripping of the sheath 60 in the communication cable 40.

[0059] Furthermore, a portion of the communication cable 40 along its extending direction is designated as a straight section 41, while another portion is designated as a curved section 42. The pair of ribs 64 demarcate the first space 65 and the second space 66 in both the straight section 41 and the curved section 42. This allows for good regulation of the positional relationship between the first insulated wire 51 and the second insulated wire 52 in both the straight section 41 and the curved section 42.

[0060] Furthermore, the distance between the conductors of the first insulated wire 51 and the second insulated wire 52 remains constant in both the straight section 41 and the bent section 42. This makes it possible to reduce noise caused by fluctuations in the relative positional relationship between the twisted wires 50, which is a problem in communication cables 40.

[0061] Furthermore, the pair of ribs 64 are provided along the entire length of the sheath 60. This allows for good control over the positional relationship between the first insulated wire 51 and the second insulated wire 52 along the entire length of the sheath 60.

[0062] Furthermore, the tips of the pair of ribs 64 are spaced apart, and the first space 65 and the second space 66 are in communication between the pair of ribs 64, while the insulating coating 54 of the first insulated wire 51 and the insulating coating 54 of the second insulated wire 52 are in direct contact without the talc layer 70 in between. This makes it possible to reduce the distance between the conductors of the first insulated wire 51 and the second insulated wire 52 and the diameter of the communication cable 40.

[0063] Furthermore, the pitch of the spirals of each pair of ribs 64 is set to be constant over the entire length of the section in which the pair of ribs 64 are provided. This makes it easier to maintain a constant pitch for the first insulated wire 51 and the second insulated wire 52 passing through the first space 65 and the second space 66, which are partitioned by the pair of ribs 64.

[0064] Furthermore, one end and the other end of the communication cable 40 along its extending direction are designated as an out-of-sheath section 43 where the twisted wire 50 extends out of the sheath 60. A first connector 80 for connecting the twisted wire 50 to the transmitter 21 is provided in the out-of-sheath section 43 at one end, and a second connector 81 for connecting the twisted wire 50 to the receiver 31 is provided in the out-of-sheath section 43 at the other end. This allows the communication cable 40 to be easily connected to both the transmitter 21 and the receiver 31.

[0065] Furthermore, the sheath 60 covers only the twisted wires 50 and the talc layer 70. This simplifies the structure of the communication cable 40 and reduces costs.

[0066] Furthermore, the powdered talc in the talc layer 70 contains magnesium hydroxide and silicate, and the powdered talc is white in color, while the color of the sheath 60 is different from the color of the powdered talc. This makes it easy to identify when the sheath 60 has been peeled by checking the color of the peeled area.

[0067] Furthermore, the average particle size of the powdered talc in the talc layer 70 is between 1 μm and 20 μm. This makes it easier to obtain good stripping properties and good characteristic impedance in the communication cable 40.

[0068] Furthermore, when the communication cable 40 is used in a vehicle, it is desirable that the communication line characteristics are within the standard range. Communication line characteristics are generally evaluated by the characteristic impedance under normal conditions. When the communication cable 40 is routed in a vehicle, at least some sections may be laid along a curved path. For this reason, it is also desirable that the communication characteristics (characteristic impedance) in the bent state be within the standard range. In the communication cable 40, the characteristic impedance in the bent state is measured using a measurement method that conforms to the measurement method specified in IEC62153-1-1, except for the following points. The measurement posture of the sample under test is a bent posture instead of the normal straight posture. This bent posture is one in which the middle part of the sample under test is bent once with a bending radius of 20 mm to form a loop, and the inside of the loop is hollow. In other words, the sample under test is bent once with a bending radius of 20 mm in the middle section, instead of the normal straight posture. This bent state is not a state where the sample is wrapped around an object, but a state where the sample under test is bent on its own. The characteristic impedance in the bent state is preferably 90Ω to 110Ω, more preferably 94Ω to 106Ω, and more preferably 97Ω to 103Ω. This makes it easier to obtain a good characteristic impedance even when the communication cable 40 is bent and arranged in the vehicle 90.

[0069] Furthermore, when the communication cable 40 is used in a vehicle, it is desirable that its communication line characteristics be within the standard range. Communication line characteristics are generally evaluated by the characteristic impedance under normal conditions. When the communication cable 40 is installed in a vehicle, there is concern about deterioration due to repeated bending caused by vibration. For this reason, it is also desirable that the communication characteristics (characteristic impedance) after repeated bending bends be within the standard range. In the case of the communication cable 40, the characteristic impedance value after a fatigue test specified in ISO 19642-2, using a weight of 300g and a mandrel diameter of 15mm, is preferably between 90Ω and 110Ω, more preferably between 94Ω and 106Ω, and more preferably between 97Ω and 103Ω. The communication cable 40 installed in the vehicle 90 is prone to repeated bending due to vibration, etc. Even in this case, if the characteristic impedance value after the fatigue test is 90Ω to 110Ω, preferably 94Ω to 106Ω, and more preferably 97Ω to 103Ω, a good characteristic impedance can be easily obtained even in the communication cable 40 after years of use.

[0070] [Examples] In this embodiment, the characteristic impedance before bending, characteristic impedance in the bent state, characteristic impedance after repeated bending, and stripping properties of samples S1-S13, which have varying configurations of the communication cable 40, are described. The evaluation was derived from characteristic impedance measurement tests and stripping tests.

[0071] <About the sample> The communication cables from Sample S1 to Sample S7 were all prepared under the conditions of having ribs and optimal sheath hardness, with the average particle size of the talc powder varied from 1 μm to 20 μm. Here, the "optimal" sheath hardness is Shore A60 to 90. Specifically, the average particle sizes of the talc powder in the communication cables from Sample S1 to Sample S7 are "1 μm", "2 μm", "3 μm", "4 μm", "6 μm", "12 μm", and "20 μm", respectively. The thickness of the talc layer in the communication cables from Sample S1 to Sample S7 can vary due to the different average particle sizes of the talc powder. Except for the thickness of the talc layer, the communication cables from Sample S1 to Sample S7 basically have the same cross-section as the communication cable 40 shown in Figure 4.

[0072] The communication cables from samples S8 to S13 are based on the communication cable of sample S4, with variations in the presence or absence of ribs, sheath hardness, or the presence or absence of a talc layer.

[0073] The communication cable of sample S8 is based on the communication cable of sample S4, with the only difference being the presence or absence of ribs, which has been changed to "no ribs". As a result of the change to "no ribs", the communication cable of sample S8 has a different cross-section from the communication cable 40 shown in Figure 4. Figure 9 is a cross-sectional view of the communication cable 100 of sample S8.

[0074] The sheath 102 in the communication cable 100 of sample S8 does not have a rib 64 that goes between the first insulated wire 51 and the second insulated wire 52. In the example shown in Figure 9, the sheath 102 has a shape corresponding to the cylindrical portion 61 of the sheath 60. The inner surface of the sheath 102 is aligned with a line corresponding to the common tangent of the first insulated wire 51 and the second insulated wire 52. An empty space 104 is created inside the sheath 102. The space 104 is provided on both sides of a line passing through the conductor centers of the first insulated wire 51 and the conductor centers of the second insulated wire 52. The space 104 extends spirally along the extending direction of the communication cable 100.

[0075] The communication cables of Samples S9 to S12 are based on the communication cable of Sample S4, with only the sheath hardness condition changed from Sample S4 to "soft," "slightly soft," "slightly hard," and "hard," respectively. The communication cables of Samples S9 to S12 have the same cross-section as the communication cable shown in Figure 4. "Soft" means a hardness of less than Shore A40. "Slightly soft" means a hardness of approximately Shore A50, between Shore A40 and 60. "Slightly hard" means a hardness of approximately Shore A95, above Shore A90 and below Shore A100. "Hard" means a hardness of above Shore A100.

[0076] The communication cable of sample S13 is based on the communication cable of sample S4, but with the only difference being the condition of the talc layer, which is changed to "-(none)". Due to the change to "-(none)" talc layer, the communication cable of sample S13 has a different cross-section from the communication cable 40 shown in Figure 4. Figure 10 is a cross-sectional view of the communication cable 200 of sample S13.

[0077] The communication cable 200 of sample S13 does not have a talc layer 70. Therefore, as shown in Figure 10, the sheath 202 of the communication cable 200 is in direct contact with the insulating coating 54 of the first insulated wire 51 and the insulating coating 54 of the second insulated wire 52. In the portion where the sheath 202 and the insulating coating 54 are in direct contact, the resin of the sheath 202 and the resin of the insulating coating 54 may fuse together.

[0078] <About evaluation symbols> In Figures 7 and 8, the symbol "◎" for characteristic impedance evaluation and peelability evaluation means the evaluation result is "Excellent". The symbol "〇" means the evaluation result is "Good". The symbol "△" means the evaluation result is "Passing". On the other hand, the symbol "×" means the evaluation result is "Failing".

[0079] <About characteristic impedance evaluation> In the characteristic impedance evaluation, a characteristic impedance of 97Ω to 103Ω was marked with "◎". A characteristic impedance of 94Ω to 106Ω that did not meet the "◎" criteria was marked with "〇". A characteristic impedance of 90Ω to 110Ω that did not meet either the "◎" or "〇" criteria was marked with "△". A characteristic impedance that did not meet the 90Ω to 110Ω criteria was marked with "×".

[0080] <Regarding Samples S1 to S7> Under the conditions of "with ribs" and "optimal" sheath hardness, samples S1 to S7, in which the average particle size of talc powder was varied, all received an evaluation of "△" or higher in pre-bending characteristic impedance evaluation, bent state characteristic impedance evaluation, and post-repeated bending characteristic impedance evaluation. Furthermore, for each of samples S1 to S7, there was no change in evaluation between the pre-bending characteristic impedance evaluation, the bent state characteristic impedance evaluation, and the post-repeated bending characteristic impedance evaluation.

[0081] Of the samples S1 to S7, sample S1, which had an average talc powder particle size of "1 μm", and sample S7, which had an average talc powder particle size of "20 μm", were evaluated as "△". Sample S2, which had an average talc powder particle size of "2 μm", and sample S7, which had an average talc powder particle size of "12 μm", were evaluated as "○". Samples S3 to S5, which had an average talc powder particle size ranging from "3 μm" to "6 μm", were evaluated as "◎".

[0082] <Regarding Samples S8 to S13> Using sample S4 as a reference, samples S8 to S13, in which one of the conditions of presence or absence of ribs, sheath hardness, or presence or absence of a talc layer was changed, all received a "◎" pre-bending characteristic impedance evaluation. Of samples S8 to S13, sample S8, which had "no" ribs, received a "△" bent state characteristic impedance evaluation and a "×" post-repeated bending characteristic impedance evaluation. Of samples S8 to S13, samples S9 and S11, which had sheath hardness set to "soft" and "slightly hard," received "○" both bent state characteristic impedance evaluations and post-repeated bending characteristic impedance evaluations. Furthermore, sample S10, which had sheath hardness set to "slightly soft," received a "◎" bent state characteristic impedance evaluation and a "○" post-repeated bending characteristic impedance evaluation. In addition, for sample S12, which had sheath hardness set to "hard," the insulating coating cracked when bent, making it impossible to evaluate the bent state characteristic impedance evaluation and post-repeated bending characteristic impedance evaluation. Of the samples S8 through S13, sample S13, which lacked a talc layer, received a "◎" rating for both its characteristic impedance evaluation in the bent state and its characteristic impedance evaluation after repeated bending.

[0083] Regarding the evaluation of characteristic impedance, the presence of ribs was found to improve the characteristic impedance in the bent state and after repeated bending. Furthermore, when a talc layer was provided, the characteristic impedance improved as the average particle size of the talc powder approached the range of "3 μm" to "6 μm". In addition, optimizing the sheath hardness was found to improve the characteristic impedance in the bent state and after repeated bending.

[0084] <Regarding the evaluation of debarking properties> In the debarking performance evaluation, the best debarking performance was marked with "◎". Additionally, good debarking performance was marked with "〇". It is possible. Items with a "△" were marked with a triangle symbol. Items with poor peeling properties were marked with a "×".

[0085] In the evaluation of peelability, sample S13, which lacked a talc layer, received a "×" rating, while samples S1 through S12, which had a talc layer, received a "△" rating or higher.

[0086] Of the seven samples, S1 to S7, in which the average particle size of the talc powder was varied, sample S1, with an average particle size of "1 μm", received a "△" rating. Sample S2, with an average particle size of "2 μm", received a "○" rating. Samples S3 to S7, with average particle sizes ranging from "3 μm" to "20 μm", received a "◎" rating.

[0087] Sample S8, which had the same average particle size and sheath hardness as Sample S4 but lacked ribs, received a "◎" rating.

[0088] Samples S9 through S12, which had the same presence or absence of ribs and average particle size of talc powder as sample S4, but differed from sample S4 in sheath hardness, were evaluated as "○" or "△".

[0089] Regarding the evaluation of peelability, the presence of a talc layer was found to improve peelability. Furthermore, an increase in the average particle size of the talc powder was observed to improve peelability. Additionally, optimizing the sheath hardness was also found to improve peelability.

[0090] [Note] Up until now, it has been described that the tips of a pair of ribs 64 are spaced apart, that a first space 65 and a second space 66 are in communication between the pair of ribs 64, and that the insulating coating 54 of the first insulated wire 51 and the insulating coating 54 of the second insulated wire 52 are in direct contact without the talc layer 70 in between. However, this is not an essential configuration. For example, the insulating coating 54 of the first insulated wire 51 and the insulating coating 54 of the second insulated wire 52 may be in contact via the talc layer 70. At least one of the first insulated wire 51 and the second insulated wire 52 may have the talc layer 70 provided around its entire circumference.

[0091] The bending position of the communication cable 40 when measuring the characteristic impedance in a bent state will be explained in more detail with reference to Figure 11. Figure 11 is a diagram showing the bending position of the communication cable 40 when measuring the characteristic impedance in a bent state. In this bending position, as shown in Figure 11, the middle part of the communication cable 40 is bent once to form a loop 44, and the loop 44 is hollow inside. The loop 44 is circular in shape with a radius of 20 mm. The section of the communication cable 40 including the loop 44 is supported on a flat horizontal surface LS such as the top surface of a table or the floor. The loop 44 is provided with an overlapping portion 45 where a part of the communication cable 40 and another part overlap. The overlapping portion 45 is the part where the part extending from the center toward one end of the section forming the loop 44 and the part extending toward the other end overlap. The overlapping portion 45 is provided so that a part of the communication cable 40 and another part overlap on the horizontal surface LS. As a result, the axial direction of the loop 44 is perpendicular to the horizontal surface LS.

[0092] To help maintain the circular shape of the loop 44, the communication cable 40 may be fixed to the horizontal plane LS by adhesive tape TP or the like. The position of the fixing part of the communication cable 40 to the horizontal plane LS can be any position that maintains the circular shape of the loop 44, and may be the position of the loop 44, but preferably it is a position other than the loop 44. The position other than the loop 44 may be near the loop 44 or at a distance from the loop 44. For example, in the example shown in Figure 11, the fixing part is provided at a position approximately the diameter of the loop 44 from the overlapping portion 45. In the example shown in Figure 11, the fixing part on one end of the loop 44 and the fixing part on the other end are provided at the same distance from the overlapping portion 45, but they may be provided at positions at different distances from the overlapping portion 45.

[0093] The loop 44 may be formed, for example, using a guide member. The guide member is a cylindrical member with a radius of 20 mm. The guide member is erected on a horizontal plane LS. The communication cable 40 is wrapped around the guide member to form the loop 44. The loop 44 is held in place by fixing the portion of the communication cable 40 on one end and the other end to the guide member, respectively, to the horizontal plane LS with adhesive tape TP or the like. After the loop 44 is formed (after being fixed with adhesive tape TP), the guide member is removed from the horizontal plane LS, resulting in the state shown in Figure 11 where the loop 44 is hollow inside. By forming the loop 44 using a guide member, the circular shape of the loop 44 tends to remain consistent.

[0094] Furthermore, the configurations described in each of the above embodiments and modifications can be combined as appropriate, as long as they do not contradict each other. [Explanation of symbols]

[0095] 10. In-vehicle communication systems 20 1st ECU 21 Transmitter 22 Parallel-to-Serial Converters 23. Connector on the first ECU side 30 2nd ECU 31 Receiver 32 Serial-Parallel Converters 33. Second ECU side connector 40 Communication Cables 41. Straight section 42 Curved Section 43 Outer section of the sheath 44 loops 45 Overlapping parts 50 twisted wires 51. First insulated wire 52. Second insulated wire 53 core wires 54 Insulating coating 60 sheath 61 Cylindrical part 62 Cylindrical section 63 Inner part 64 Ribs 65 1st space 66 2nd space 70 Talc layer 80 First connector 81 Second connector 82 Connector terminals 83 Connector Housing 90 vehicles 100, 200 communication cables 102, 202 sheath 104 spaces LS horizontal plane TP Adhesive Tape

Claims

1. A transmitter that transmits differential signals, A receiver that receives the differential signal, A communication cable connecting the transmitter and the receiver and transmitting the differential signal, Equipped with, The aforementioned communication cable is A twisted wire formed by twisting together a first insulated wire and a second insulated wire, A sheath covering the aforementioned twisted wire, A talc layer is provided between the twisted wire and the sheath, Includes, The sheath has a cylindrical portion surrounding the first insulated wire and the second insulated wire, and a pair of ribs that each protrude inward from the cylindrical portion between the first insulated wire and the second insulated wire, and extend spirally in the direction of the extension of the communication cable. In the cross-section of the communication cable, the pair of ribs are positioned on either side of a straight line connecting the conductor center of the first insulated wire and the conductor center of the second insulated wire, so as to divide the first space where the first insulated wire is arranged and the second space where the second insulated wire is arranged. The talc layer is provided along the surface of the twisted wire, The tips of the pair of ribs are spaced apart from each other. Between the pair of ribs, the first space and the second space are in communication, and the insulating coating of the first insulated wire and the insulating coating of the second insulated wire are in direct contact without the talc layer in between. The insulating coating of the first coated wire and the insulating coating of the second coated wire are not fused to each other. An in-vehicle communication system in which the only linear components located inside the sheath are the first insulated wire and the second insulated wire.

2. The in-vehicle communication system according to claim 1, A portion of the communication cable along its extending direction is designated as a straight section, while another portion is designated as a curved section. An in-vehicle communication system in which the pair of ribs demarcate the first space and the second space in both the straight section and the curved section.

3. The in-vehicle communication system according to claim 2, An in-vehicle communication system in which the distance between the conductors of the first insulated wire and the second insulated wire is constant in both the straight section and the bent section.

4. An in-vehicle communication system according to any one of claims 1 to 3, An in-vehicle communication system in which the pair of ribs are provided along the entire length of the sheath.

5. An in-vehicle communication system according to any one of claims 1 to 3, An in-vehicle communication system in which the pitch of the helices of each of the pair of ribs is set to be constant over the entire length of the section in which the pair of ribs are provided.

6. An in-vehicle communication system according to any one of claims 1 to 3, One end and the other end of the communication cable along its extending direction are defined as an out-of-sheath section where the twisted wire extends outside the sheath. An in-vehicle communication system, wherein a first connector for connecting the twisted wire and the transmitter is provided in the outer sheath section of one end, and a second connector for connecting the twisted wire and the receiver is provided in the outer sheath section of the other end.

7. An in-vehicle communication system according to any one of claims 1 to 3, The sheath covers only the twisted wire and the talc layer in an in-vehicle communication system.

8. An in-vehicle communication system according to any one of claims 1 to 3, The powdered talc in the talc layer contains magnesium hydroxide and silicate, The aforementioned powdered talc is white in color. The color of the sheath is different from the color of the powdered talc in the in-vehicle communication system.

9. An in-vehicle communication system according to any one of claims 1 to 3, An in-vehicle communication system in which the average particle size of powdered talc in the talc layer is 1 μm to 20 μm.

10. An in-vehicle communication system according to any one of claims 1 to 3, The following is a method for measuring characteristic impedance: <Method for measuring characteristic impedance> The measurement method conforms to IEC 62153-1-1, except for the following points: The measurement position of the sample under test was changed from the usual straight position to a bent position. The aforementioned bending posture is such that the middle portion of the sample to be measured is bent once around with a bending radius of 20 mm to form a loop, and the inside of the loop is hollow; An in-vehicle communication system in which the characteristic impedance value of the communication cable in a bent state, measured by [method / tool ​​name], is between 94 Ω and 106 Ω.

11. An in-vehicle communication system according to any one of claims 1 to 3, An in-vehicle communication system in which, after a fatigue test specified in ISO 19642-2, using a 300g weight and a 15mm diameter mandrel, the characteristic impedance value measured by a measurement method compliant with IEC 62153-1-1 is between 94Ω and 106Ω.

12. A communication cable used in an in-vehicle communication system using differential signaling, A twisted wire formed by twisting together a first insulated wire and a second insulated wire, A sheath that covers the aforementioned twisted wires together, A talc layer is provided between the twisted wire and the sheath, Equipped with, The sheath has a cylindrical portion surrounding the first insulated wire and the second insulated wire, and a pair of ribs that each protrude inward from the cylindrical portion between the first insulated wire and the second insulated wire, and extend spirally in the direction of the extension of the communication cable. In the cross-section of the communication cable, the pair of ribs are positioned on either side of a straight line connecting the conductor center of the first insulated wire and the conductor center of the second insulated wire, so as to divide the first space where the first insulated wire is arranged and the second space where the second insulated wire is arranged. The talc layer is provided along the surface of the twisted wire, The tips of the pair of ribs are spaced apart from each other. Between the pair of ribs, the first space and the second space are in communication, and the insulating coating of the first insulated wire and the insulating coating of the second insulated wire are in direct contact without the talc layer in between. The insulating coating of the first coated wire and the insulating coating of the second coated wire are not fused to each other. A communication cable in which the linear members located inside the sheath consist of only two wires: the first insulated wire and the second insulated wire.

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