On-vehicle communication system

Abstract

To provide an on-vehicle communication system which is capable of restraining ringing which generates in in-vehicle LAN adequately.SOLUTION: An on-vehicle communication system 10 comprises a terminal node 201 which is provided with a SIC transceiver and a terminal resistance. In addition, the on-vehicle communication system 10 comprises a first branch line node 202 which is provided with the SIC transceiver and a second branch line node 203. In addition, the on-vehicle communication system 10 comprises a junction connector 100 which includes a terminal connector 111, a first connector 112 and a second connector 113. The junction connector 100 comprises a filter on the first connector 112 if the length of a first branch line 302 is a prescribed length or more than one of a terminal branch line 301 or a second branch line 303. In addition, the junction connector 100 comprises a filter on the second connector 113 if the length of the second branch line 303 is a prescribed length or more than one of the terminal branch line 301 or the first branch line 302.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an in-vehicle communication system. [Background technology]

[0002] Conventionally, techniques have been proposed for suppressing ringing, which is a phenomenon in which the waveform of a signal transmitted and received in an in-vehicle LAN is distorted due to reflected waves, etc. Patent Document 1 discloses a junction connector equipped with a filter circuit for removing ringing. The junction connector disclosed in Patent Document 1 attenuates the amount of reflection by inserting resistors that function as filter circuits in each communication line, thereby reducing ringing in the communication line. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-67543 A Summary of the Invention [Problem to be solved by the invention]

[0004] The junction connector disclosed in Patent Document 1 is provided with a filter function on all communication lines from each ECU within the junction connector. Meanwhile, in recent years, SIC transceivers (Signal Improvement Capability) have been used as a ringing suppression technology built into CAN drivers that constitute an in-vehicle LAN. For example, when a SIC transceiver is used in the junction connector disclosed in Patent Document 1, problems arise such as increased costs and excessive performance due to the provision of filters on all communication lines.

[0005] The present invention has been made in consideration of the problems inherent in the conventional techniques, and an object of the present invention is to provide an in-vehicle communication system capable of appropriately suppressing ringing that occurs in an in-vehicle LAN. [Means for solving the problem]

[0006] An in-vehicle communication system according to an embodiment of the present invention is an in-vehicle communication system that is installed in a vehicle and transmits and receives communication data between a plurality of ECUs based on a communication protocol, and includes: a termination node that is an ECU that has a SIC transceiver and a termination resistor and transmits the communication data; a first branch node that is an ECU that has a SIC transceiver and transmits or receives the communication data; a second branch node that is an ECU that has a SIC transceiver and transmits or receives the communication data; and a junction connector having a termination connector connected to the termination node via the termination branch, a first connector connected to the first branch node via the first branch, and a second connector connected to the second branch node via the second branch, wherein the junction connector includes a filter for suppressing ringing in the first connector when the length of the first branch is a predetermined length or more than either the termination branch or the second branch, and includes a filter in the second connector when the length of the second branch is a predetermined length or more than either the termination branch or the first branch. Effect of the Invention

[0007] According to the present invention, it is possible to provide a junction connector capable of appropriately suppressing ringing that occurs in an in-vehicle LAN. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing a configuration of an in-vehicle communication system according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a diagram for explaining a connection example of the in-vehicle communication system according to the embodiment. [Figure 3A] 1 is a perspective view showing the appearance of a junction connector according to an embodiment of the present invention; [Figure 3B] 5A to 5C are diagrams for explaining a connector portion of a junction connector according to the embodiment. [Figure 4A] 4 is a diagram for explaining a predetermined length applied in the in-vehicle communication system according to the embodiment. FIG. [Figure 4B] 4 is a diagram for explaining a predetermined length applied in the in-vehicle communication system according to the embodiment. FIG. [Figure 4C] 4 is a diagram for explaining a predetermined length applied in the in-vehicle communication system according to the embodiment. FIG. [Diagram 5] 1 is a diagram for explaining application of a filter in an in-vehicle communication system according to an embodiment of the present invention; [Figure 6A] 5 is a diagram for explaining a peak value of ringing in the in-vehicle communication system according to the embodiment. FIG. [Figure 6B] 5 is a diagram for explaining a peak value of ringing in the in-vehicle communication system according to the embodiment. FIG. [Figure 7A] 5 is a diagram for explaining a peak value reduction rate in the in-vehicle communication system according to the embodiment. FIG. [Figure 7B] 5 is a diagram for explaining a peak value reduction rate in the in-vehicle communication system according to the embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The in-vehicle communication system 10 according to the present embodiment will be described in detail below with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for the sake of explanation and may differ from the actual ratios. In addition, in the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0010] Fig. 1 is a diagram showing the configuration of an in-vehicle communication system 10 according to this embodiment. As shown in Fig. 1, the in-vehicle communication system 10 includes a plurality of ECUs 200 (Electronic Control Units) and a junction connector 100 (J / C).

[0011] The in-vehicle communication system 10 according to the present embodiment is a communication system that is provided in a vehicle and transmits and receives communication data between a plurality of ECUs 200 based on a communication protocol.

[0012] The in-vehicle communication system 10 applies CAN-FD (Controller Area Network with Flexible Data Rate) as a communication protocol. In the in-vehicle communication system 10 according to the present embodiment, communication data is transmitted and received at a communication speed of 2 Mbps or more and 5 Mbps or less among the communication speeds of 500 kbps to 5 Mbps based on the CAN-FD communication protocol.

[0013] In FIG. 1, the ECU 1 includes a SIC transceiver (not shown) and a termination resistor (not shown), and corresponds to a termination node 201 that transmits communication data.

[0014] The SIC transceiver is a general SIC transceiver that meets the ISO (International Organization for Standardization) 11898-2:2016 high-speed CAN physical layer standard and the CiA (CAN-in-Automation) 601-4 signal improvement specification. By equipping each ECU 200 with a SIC transceiver, it becomes possible to reduce waveform distortion such as ringing that occurs during communication.

[0015] 1, ECU2 corresponds to a first branch node 202 that includes a SIC transceiver and transmits or receives communication data, and ECU3 corresponds to a second branch node 203 that includes a SIC transceiver and transmits or receives communication data.

[0016] In the following description, when there is no need to distinguish between the end node 201 (ECU1), the first branch node 202 (ECU2), and the second branch node 203 (ECU3), they will simply be referred to as "ECU 200."

[0017] The junction connector 100 is a relay connection unit that relays communication data transmitted and received from the ECU 200 and also provides a sufficient number of branches to enable connection to a large number of ECUs 200.

[0018] The junction connector 100 also includes a trunk connector 114 for connection to a trunk line 304. The junction connector 100 is capable of connection to other junction connectors 100 via the trunk connector 114 and the trunk line 304.

[0019] FIG. 2 is a diagram for explaining a connection example of the in-vehicle communication system 10 according to the present embodiment. In the example shown in FIG. 2, a junction connector 100 connected to ECU1 to ECU3 is connected to a junction connector 100 connected to ECU4 to ECU6 via a trunk line 304. The junction connector 100 may have a terminal connector 111, a first connector 112, and a second connector 113, which will be described later, as a trunk line connector 114, and may be further connected to another junction connector 100. In this way, by connecting the junction connector 100 in the in-vehicle communication system 10 to another junction connector 100, the number of communicable ECUs 200 can be increased, and an in-vehicle communication network can be flexibly constructed according to the system of the vehicle.

[0020] 3A is a perspective view showing the appearance of the junction connector 100 according to this embodiment. The junction connector 100 has a plurality of connector portions 110 (see FIG. 3B), and is connected to each ECU 200 via the connector portions 110.

[0021] Fig. 3B is a diagram for explaining the connector portion 110 of the junction connector 100 according to this embodiment. Fig. 3B is a schematic diagram of the front of the junction connector 100 viewed from the left in the drawing on the XY plane in Fig. 3A.

[0022] As shown in FIG. 3B, on the front side of the junction connector 100, a terminating connector 111 that is connected to a terminating node 201 via a terminating branch line 301 is provided as a connector section 110.

[0023] The front of the junction connector 100 has a first connector 112 connected to the first branch node 202 via a first branch 302, and a second connector 113 connected to the second branch node 203 via a second branch 303. In the following description, when there is no need to distinguish between the terminal connector 111, the first connector 112, the second connector 113, and the trunk connector 114, they will be simply referred to as the "connector section 110."

[0024] In the CAN-FD applied to the in-vehicle communication system 10 according to this embodiment, communication is performed with reduced influence of external noise by a two-wire differential voltage method using two wires (twisted pair).

[0025] The junction connector 100 suppresses waveform distortion such as ringing that occurs during communication by providing a filter in the first connector 112 or the second connector 113. However, the in-vehicle communication system 10 according to this embodiment is characterized in that filters are provided only when a predetermined condition is satisfied, rather than providing filters in all connectors. This makes it possible for the in-vehicle communication system 10 according to this embodiment to prevent an increase in cost and excessive performance that would otherwise occur if filters were provided in all communication lines, and to appropriately suppress ringing that occurs in the in-vehicle LAN.

[0026] The filter applied in this embodiment is a low-pass filter. This enables the in-vehicle communication system 10 to reduce waveform distortion and noise at high frequencies. The low-pass filter in this embodiment may be an LR low-pass filter configured with a general L (inductor) and R (resistor). The low-pass filter in this embodiment may also be configured by combining multiple LR low-pass filters in a ladder shape.

[0027] In the in-vehicle communication system 10 according to this embodiment, whether or not to provide a filter in the connector of the junction connector 100 is determined based on the following formula (1). That is, the junction connector 100 is provided with a filter in the connector when the "branch line length of the receiving ECU" is a predetermined length or more longer than the "line length of the transmitting ECU". Note that the predetermined length in this embodiment is 1 m. Furthermore, the "line length of the transmitting ECU" is the length of the terminating branch line 301 in the case of the terminal node 201, and corresponds to the length of the first branch line 302 or the second branch line 303 in the case of the first branch node 202 or the second branch node 203. [Number 1] Length of branch line of receiving ECU – Length of line of sending ECU ≥ 1 (1)

[0028] That is, when the length of the first branch line 302 is a predetermined length or longer than either the terminal branch line 301 or the second branch line 303, the junction connector 100 includes a filter in the first connector 112 for suppressing ringing.

[0029] Furthermore, in the case where the length of the second branch line 303 is a predetermined length or longer than either the terminal branch line 301 or the first branch line 302, the junction connector 100 includes a filter in the second connector 113.

[0030] In this embodiment, the predetermined length of 1 m is determined based on the results of a circuit simulation shown in Figures 4A to 4C. In a simplified configuration shown in Figure 4A that includes ECU1 to ECU4 and a junction connector 100, ECU2 is set as a transmitting ECU (Tx) and ECU3 is set as a receiving ECU (Rx), and the relationship between the line length difference between ECU3 and ECU2 and the voltage value of ringing is measured.

[0031] In the configuration shown in Fig. 4A, the waveform in ECU3 measured with the dominant voltage Vdiff = 3.0V and the capacitance C of ECU1 to ECU4 = 100pF is shown in Fig. 4B. In the waveform shown in Fig. 4B, an inclusive line is drawn for the ringing that occurs, and the voltage value of the inclusive line that intersects with the position 100ns from the falling edge of the waveform shown in Fig. 4B is extracted. Note that this 100ns is a value that takes into account the allowable delay time when the communication speed is 5Mbps.

[0032] Figure 4C shows the results of the line length difference and the voltage value extracted from the inclusive line when the line length of ECU2 and ECU3 is changed. As shown in Figure 4C, the voltage value increases as the line length difference increases. In addition, depending on the reception performance of the SIC transceiver, a bit error may occur at 0.5V. Therefore, in this embodiment, the application of a filter is considered at the boundary of 0.5V, and the predetermined length is set to a line length difference of 1m.

[0033] Note that the specified length of 1 m does not limit the configuration of the embodiment of the present invention, and a value longer or shorter than 1 m may be applied depending on the communication speed based on the communication protocol applied to the system.

[0034] Fig. 5 is a diagram for explaining application of filters in the in-vehicle communication system 10 according to this embodiment. In the example shown in Fig. 5, seven patterns are shown from the top, including "0 filter pairs" (no filter), "1 filter pair" (3 patterns), "2 filter pairs" (2 patterns), and "3 filter pairs" (filters in all connectors). In the example shown in Fig. 5, the connector section 110 in which the filter is provided is shown with a schematic pattern (hatching).

[0035] Figures 6A to 7B show the results of measuring the waveform of the differential voltage in each of the seven patterns shown in Figure 5 and confirming the effect of the reduction rate of the ringing peak value. In the example shown in Figures 6A to 7B, the lengths of the terminal branch 301, the first branch 302 and the second branch 303 are measured as 1 m, 1 m and 3 m, respectively, as shown in Figure 2. In the example shown in Figures 6A to 7B, an example is shown in which communication data is transmitted and received at a communication speed of 2 Mbps.

[0036] In this embodiment, the original rate of the peak value is calculated based on the following formula (2). Here, PRR indicates the peak value reduction rate. Furthermore, Px indicates the second peak value in the six patterns from filter pair 1 to filter pair 3 shown in Fig. 5. Furthermore, P0 indicates the second peak value in the case of no filter. [Number 2] PRR = (1-(Px / P0))×100 (2)

[0037] 6A is a diagram for explaining the peak value of ringing in the in-vehicle communication system 10 according to this embodiment, and shows a waveform when communication data is transmitted from the terminal node 201 (ECU1) and received by the second branch node 203 (ECU3). In the waveform shown in FIG. 6A, the rate of decrease at the peak (second peak) shown by the dashed line rectangle is confirmed.

[0038] FIG. 6B is a diagram for explaining the peak value of the ringing in the in-vehicle communication system 10 according to this embodiment, and shows the reduction rate of the second peak value shown in FIG. 6A. As shown in FIG. 6B, when one pair of filters is provided in the second connector 113 of the second branch node 203 (ECU 3), a reduction rate similar to that of two or three pairs of filters can be obtained. In addition, a reduction rate effect is obtained compared to when one pair of filters is provided in the termination connector 111 or the first connector 112. That is, in the in-vehicle communication system 10 according to this embodiment, it is possible to obtain an effect similar to that of when the connector portion 110 is provided in all connector portions 110 while providing a minimum number of filters in the connector portion 110 of the junction connector 100.

[0039] Fig. 7A is a diagram for explaining the peak value reduction rate in the in-vehicle communication system 10 according to this embodiment, and shows a waveform when communication data is transmitted from the first branch node 202 (ECU2) and received by the second branch node 203 (ECU3). In the waveform shown in Fig. 7A, the reduction rate at the peak (second peak) shown by the dashed line rectangle is confirmed, as in the case of Fig. 6A.

[0040] FIG. 7B is a diagram for explaining the peak value reduction rate in the in-vehicle communication system 10 according to this embodiment, and shows the reduction rate of the second peak value shown in FIG. 7A. As shown in FIG. 7B, when one pair of filters is provided in the second connector 113 of the second branch node 203 (ECU 3), a reduction rate similar to that of two or three pairs of filters can be obtained. In addition, compared to when one pair of filters is provided in the termination connector 111 or the first connector 112, a reduction rate effect is obtained. That is, in the in-vehicle communication system 10 according to this embodiment, it is possible to obtain an effect similar to that of when the connector portion 110 is provided in all connector portions 110 while providing a minimum number of filters in the connector portion 110 of the junction connector 100.

[0041] As described above, the in-vehicle communication system 10 according to the present embodiment is provided in a vehicle and transmits and receives communication data between a plurality of ECUs 200 based on a communication protocol. The in-vehicle communication system 10 includes a terminal node 201 that is an ECU 200 that includes a SIC transceiver and a termination resistor and transmits communication data. The in-vehicle communication system 10 also includes a first branch node 202 that is an ECU 200 that includes a SIC transceiver and transmits or receives communication data. The in-vehicle communication system 10 also includes a second branch node 203 that is an ECU 200 that includes a SIC transceiver and transmits or receives communication data. The in-vehicle communication system 10 also includes a junction connector 100. The junction connector 100 includes a terminal connector 111 that is connected to the terminal node 201 via a terminal branch 301. The junction connector 100 also includes a first connector 112 that is connected to the first branch node 202 via a first branch 302. Furthermore, the junction connector 100 has a second connector 113 connected to the second branch node 203 via the second branch 303. The junction connector 100 includes a filter in the first connector 112 for suppressing ringing when the length of the first branch 302 is a predetermined length or longer than either the terminating branch 301 or the second branch 303. The junction connector 100 also includes a filter in the second connector 113 when the length of the second branch 303 is a predetermined length or longer than either the terminating branch 301 or the first branch 302.

[0042] This allows the in-vehicle communication system 10 to prevent increases in costs and excessive performance due to the provision of filters on all communication lines, and to appropriately suppress ringing that occurs in the in-vehicle LAN.

[0043] The predetermined value in the in-vehicle communication system 10 according to the present embodiment may be 1 m. This enables the in-vehicle communication system 10 to more appropriately suppress ringing that occurs in an in-vehicle LAN to which CAN-FD is applied.

[0044] Furthermore, the communication data transmitted and received in the in-vehicle communication system 10 according to the present embodiment may be transmitted and received at a communication speed of 2 Mbps or more and 5 Mbps or less based on a communication protocol. This allows the in-vehicle communication system 10 to obtain the effect of using a SIC transceiver and a filter in combination in communication between ECUs 200 equipped with a SIC transceiver.

[0045] The filter applied to the junction connector 100 of the in-vehicle communication system 10 according to the present embodiment may be a low-pass filter, which enables the in-vehicle communication system 10 to reduce waveform distortion and noise at high frequencies.

[0046] Furthermore, the in-vehicle communication system 10 according to this embodiment may include a trunk connector 114 for connecting to another in-vehicle communication system 10 via a trunk 304. This allows the in-vehicle communication system 10 to increase the number of communicable ECUs 200 by connecting the junction connector 100 to another junction connector 100, thereby making it possible to flexibly configure an in-vehicle communication network according to the system of the vehicle.

[0047] (Other embodiments) Although the embodiments have been described in detail with reference to the drawings, the present embodiments are not limited to the contents described in the above embodiments. The components described above include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the configurations described above can be appropriately combined. Various omissions, substitutions, or modifications of the configurations can be made without departing from the spirit of the embodiments.

[0048] The features of the in-vehicle communication system 10 will be described below.

[0049] The in-vehicle communication system 10 according to the first embodiment is provided in a vehicle and transmits and receives communication data between a plurality of ECUs 200 based on a communication protocol. The in-vehicle communication system 10 includes a terminal node 201 that is an ECU 200 that includes a SIC transceiver and a termination resistor and transmits communication data. The in-vehicle communication system 10 also includes a first branch node 202 that is an ECU 200 that includes a SIC transceiver and transmits or receives communication data. The in-vehicle communication system 10 also includes a second branch node 203 that is an ECU 200 that includes a SIC transceiver and transmits or receives communication data. The in-vehicle communication system 10 also includes a junction connector 100. The junction connector 100 includes a terminal connector 111 that is connected to the terminal node 201 via a terminal branch 301. The junction connector 100 also includes a first connector 112 that is connected to the first branch node 202 via a first branch 302. Furthermore, the junction connector 100 has a second connector 113 connected to the second branch node 203 via the second branch 303. The junction connector 100 includes a filter in the first connector 112 for suppressing ringing when the length of the first branch 302 is a predetermined length or longer than either the terminating branch 301 or the second branch 303. The junction connector 100 also includes a filter in the second connector 113 when the length of the second branch 303 is a predetermined length or longer than either the terminating branch 301 or the first branch 302.

[0050] According to the above configuration, the in-vehicle communication system 10 can prevent increases in costs and excessive performance due to the need to provide filters on all communication lines, and can appropriately suppress ringing that occurs in the in-vehicle LAN.

[0051] The predetermined value in the in-vehicle communication system 10 according to the second embodiment may be 1 m.

[0052] According to the above configuration, the in-vehicle communication system 10 can more appropriately suppress ringing that occurs in an in-vehicle LAN to which CAN-FD is applied.

[0053] The communication data transmitted and received in the in-vehicle communication system 10 according to the third embodiment may be transmitted and received at a communication speed of 2 Mbps or more and 5 Mbps or less based on a communication protocol.

[0054] According to the above configuration, the in-vehicle communication system 10 can obtain the effect of using the SIC transceiver and the filter in combination in the communication between the ECUs 200 equipped with the SIC transceiver.

[0055] The filter applied in the junction connector 100 of the in-vehicle communication system 10 according to the fourth embodiment may be a low-pass filter.

[0056] According to the above configuration, the in-vehicle communication system 10 can reduce waveform distortion and noise at high frequencies.

[0057] The in-vehicle communication system 10 according to the fifth embodiment may include a trunk line connector 114 for connecting to another in-vehicle communication system 10 via a trunk line 304.

[0058] According to the above configuration, the in-vehicle communication system 10 can increase the number of ECUs 200 with which it can communicate by connecting the junction connector 100 to other junction connectors 100, thereby making it possible to flexibly construct an in-vehicle communication network that is suited to the vehicle's system. [Explanation of symbols]

[0059] 10. In-vehicle communication systems 100 Junction Connector 110 Connector part 111 Termination Connector 112 First Connector 113 Second Connector 114 Trunk Connector 200 ECU 201 End Node 202 First Branch Node 203 Second branch node 301 Terminal branch line 302 1st branch line 303 2nd branch line 304 Main line

Claims

1. An in-vehicle communication system that is provided in a vehicle and transmits and receives communication data between a plurality of ECUs based on a communication protocol, a terminal node which is the ECU including a SIC transceiver and a terminal resistor and transmits the communication data; a first branch node which is the ECU including the SIC transceiver and transmits or receives the communication data; a second branch node which is the ECU including the SIC transceiver and transmits or receives the communication data; a junction connector having a termination connector connected to the termination node via a termination branch line, a first connector connected to the first branch node via a first branch line, and a second connector connected to the second branch node via a second branch line, The junction connector comprises: a filter for suppressing ringing in the first connector when the length of the first branch line is a predetermined length or longer than either one of the terminal branch line or the second branch line; An in-vehicle communication system comprising: the second connector and the filter when the length of the second branch is equal to or longer than the predetermined length of either the terminal branch or the first branch.

2. The in-vehicle communication system according to claim 1 , wherein the predetermined value is 1 m.

3. The in-vehicle communication system according to claim 1 , wherein the communication data is transmitted and received at a communication speed of 2 Mbps or more and 5 Mbps or less based on the communication protocol.

4. The in-vehicle communication system according to claim 1 , wherein the filter is a low-pass filter.

5. 4. The vehicle-mounted communication system according to claim 1, further comprising a trunk line connector for connecting to the other vehicle-mounted communication system via a trunk line.

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